NDE of polymeric composite material bridge components

NASA Astrophysics Data System (ADS)

Duke, John C., Jr.; Horne, Michael R.

1998-03-01

Rapid advancements with respect to utilization of polymeric composite materials for bridge components is occurring. This situation is driven primarily by the potential improvements offered by these materials with respect to long term durability. However, because of the developmental nature of these materials much of the materials characterization has involved short term testing without the synergistic effects of environmental exposure. Efforts to develop nondestructive evaluation procedures, essential for any wide spread use in critical structural applications, have been consequently limited. This paper discuses the effort to develop NDE methods for field inspection of hybrid glass and carbon fiber reinforced vinyl ester pultruded 'double box' I beams that are installed in a small bridge over Tom's Creek, in Blacksburg, Virginia. Integrated structural element sensors, dormant infrared devices, as well as acousto-ultrasonic methods are under development for detecting and monitoring the occurrence and progression of life limiting deterioration mechanisms.

Biodegradable containers from green waste materials

NASA Astrophysics Data System (ADS)

Sartore, Luciana; Schettini, Evelia; Pandini, Stefano; Bignotti, Fabio; Vox, Giuliano; D'Amore, Alberto

2016-05-01

Novel biodegradable polymeric materials based on protein hydrolysate (PH), derived from waste products of the leather industry, and poly(ethylene glycol) diglycidyl ether (PEG) or epoxidized soybean oil (ESO) were obtained and their physico-chemical properties and mechanical behaviour were evaluated. Different processing conditions and the introduction of fillers of natural origin, as saw dust and wood flour, were used to tailor the mechanical properties and the environmental durability of the product. The biodegradable products, which are almost completely manufactured from renewable-based raw materials, look promising for several applications, particularly in agriculture for the additional fertilizing action of PH or in packaging.

Materials research for High Speed Civil Transport and generic hypersonics: Adhesive durability

NASA Technical Reports Server (NTRS)

Allen, Mark R.

1995-01-01

This report covers a portion of an ongoing investigation of the durability of adhesives for the High Speed Civil Transport (HSCT) program. Candidate HSCT adhesives need to possess the high-temperature capability required for supersonic flight. This program was designed to initiate an understanding of the behavior of candidate HSCT materials when subjected to combined mechanical and thermal loads. Two adhesives (K3A and FM57) and two adherends (IM7/K3B polymeric composite and the titanium alloy Ti-6Al-4V) were used to fabricate thick adherend lap shear specimens. Due to processing problems, only the FM57/titanium bonds could be fabricated successfully. These are currently undergoing thermomechanical fatigue (TMF) testing. There is an acute need for an adhesive to secondarily bond polymeric composite adherends or, alternately, polymeric composites that remain stable at the processing temperatures of today's adhesives.

Carbon Nanotube/Space Durable Polymer Nanocomposite Films for Electrostatic Charge Dissipation

NASA Technical Reports Server (NTRS)

Smith, J. G., Jr.; Watson, K. A.; Thompson, C. M.; Connell, J. W.

2002-01-01

Low solar absorptivity, space environmentally stable polymeric materials possessing sufficient electrical conductivity for electrostatic charge dissipation (ESD) are of interest for potential applications on spacecraft as thin film membranes on antennas, solar sails, large lightweight space optics, and second surface mirrors. One method of imparting electrical conductivity while maintaining low solar absorptivity is through the use of single wall carbon nanotubes (SWNTs). However, SWNTs are difficult to disperse. Several preparative methods were employed to disperse SWNTs into the polymer matrix. Several examples possessed electrical conductivity sufficient for ESD. The chemistry, physical, and mechanical properties of the nanocomposite films will be presented.

Fluid Dynamic Characterization of a Polymeric Heart Valve Prototype (Poli-Valve) tested under Continuous and Pulsatile Flow Conditions

PubMed Central

De Gaetano, Francesco; Serrani, Marta; Bagnoli, Paola; Brubert, Jacob; Stasiak, Joanna; Moggridge, Geoff D.; Costantino, Maria Laura

2016-01-01

Introduction Only mechanical and biological heart valve prostheses are currently commercially available. The former show longer durability but require anticoagulant therapy, the latter display better fluid dynamic behaviour but do not have adequate durability. New Polymeric Heart Valves (PHVs) could potentially combine the haemodynamic properties of biological valves with the durability of mechanical valves. This work presents a hydrodynamic evaluation of two groups of newly developed supra-annular tri-leaflet prosthetic heart valves made from styrenic block copolymers (SBC): Poli-Valves. Methods Two types of Poli-Valves made of SBC differing in polystyrene fraction content were tested under continuous and pulsatile flow conditions as prescribed by ISO 5840 Standard. An ad - hoc designed pulse duplicator allowed the valve prototypes to be tested at different flow rates and frequencies. Pressure and flow were recorded; pressure drops, effective orifice area (EOA), and regurgitant volume were computed to assess the valve’s behaviour. Results Both types Poli-Valves met the minimum requirements in terms of regurgitation and EOA as specified by ISO 5840 Standard. Results were compared with five mechanical heart valves (MHVs) and five tissue heart valves (THVs), currently available on the market. Conclusion Based on these results, polymeric heart valves based on styrenic block copolymers, as Poli-Valves are, can be considered as promising alternative for heart valve replacement in near future. PMID:26689146

Multi-functional Textiles for Military Applications

NASA Astrophysics Data System (ADS)

Malshe, Priyadarshini

The objective of this research was to develop the standard rip-stop weave military uniform fabric made of 50/50 nylon/cotton (NyCo) to achieve a repellent front surface and an antibacterial bulk for protection from chemical-biological warfare agents. Diallyldimethylammonium chloride (DADMAC), a quaternary ammonium salt monomer was graft polymerized on NyCo fabric to impart antimicrobial capability using atmospheric pressure glow discharge plasma. Plasma was used to induce free radical chain polymerization of the DADMAC monomer to introduce a graft polymerized network on the fabric with durable antimicrobial properties. Pentaerythritol tertraacrylate was used as a cross-linking agent to obtain a highly cross-linked, durable polymer network. The presence of polyDADMAC on the fabric surface was confirmed using acid dye staining, SEM, and TOF-SIMS. Antibacterial performance was evaluated using standard AATCC test method 100 for both gram positive and gram negative bacteria. Results showed 99.9% reduction in the bacterial activities of K. pneumoniae and S. aureus. To achieve repellency on NyCo front surface, an environmentally benign C6 fluorocarbon monomer, 2-(perfluorohexyl) ethyl acrylate was graft polymerized using plasma on the front surface of the NyCo fabric which was already grafted with polyDADMAC for anti-microbial properties. The surface was characterized by IR spectroscopy and XPS. The presence of fluorine on the surface was mapped and confirmed by TOF-SIMS. SEM images showed a uniform layer of fluorocarbon polymer on the fiber surface. High water contact angle of 144° was obtained on the surface. The surface also achieved a high AATCC Test Method 193 rating of 9 and AATCC Test Method 118 rating of 5, indicating that the surface could repel a fluid with surface tension as low as 24 dynes/cm. Appropriate experimental designs and statistical modeling of data helped identify the experimental space and optimal factor combinations for best response. The study helped create a multi-functional fabric with an anti-bacterial bulk, hydrophilic back surface and repellent front surface for enhanced protective and aesthetic values.

Flexible fluoropolymer filled protective coatings

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Mirtich, Michael J.; Sovey, James S.; Nahra, Henry; Rutledge, Sharon K.

1991-01-01

Metal oxide films such as SiO2 are known to provide an effective barrier to the transport of moisture as well as gaseous species through polymeric films. Such thin film coatings have a tendency to crack upon flexure of the polymeric substrate. Sputter co-deposition of SiO2 with 4 to 15 percent fluoropolymers was demonstrated to produce thin films with glass-like barrier properties that have significant increases in strain to failure over pure glass films which improves their tolerance to flexure on polymeric substrates. Deposition techniques capable of producing these films on polymeric substrates are suitable for durable food packaging and oxidation/corrosion protection applications.

Transparent Metal-Salt-Filled Polymeric Radiation Shields

NASA Technical Reports Server (NTRS)

Edwards, David; Lennhoff, John; Harris, George

2003-01-01

"COR-RA" (colorless atomic oxygen resistant -- radiation shield) is the name of a transparent polymeric material filled with x-ray-absorbing salts of lead, bismuth, cesium, and thorium. COR-RA is suitable for use in shielding personnel against bremsstrahlung radiation from electron-beam welding and industrial and medical x-ray equipment. In comparison with lead-foil and leaded-glass shields that give equivalent protection against x-rays (see table), COR-RA shields are mechanically more durable. COR-RA absorbs not only x-rays but also neutrons and rays without adverse effects on optical or mechanical performance. The formulation of COR-RA with the most favorable mechanical-durability and optical properties contains 22 weight percent of bismuth to absorb x-rays, plus 45 atomic percent hydrogen for shielding against neutrons.

Polymeric heart valves for surgical implantation, catheter-based technologies and heart assist devices.

PubMed

Bezuidenhout, Deon; Williams, David F; Zilla, Peter

2015-01-01

Efficient function and long-term durability without the need for anticoagulation, coupled with the ability to be accommodated in many different types of patient, are the principal requirements of replacement heart valves. Although the clinical use of valves appeared to have remained steady for several decades, the evolving demands for the elderly and frail patients typically encountered in the developed world, and the needs of much younger and poorer rheumatic heart disease patients in the developing world have now necessitated new paradigms for heart valve technologies and associated materials. This includes further consideration of durable elastomeric materials. The use of polymers to produce flexible leaflet valves that have the benefits of current commercial bioprosthetic and mechanical valves without any of their deficiencies has been held desirable since the mid 1950s. Much attention has been focused on thermoplastic polyurethanes in view of their generally good physico-chemical properties and versatility in processing, coupled with the improving biocompatibility and stability of recent formulations. Accelerated in vitro durability of between 600 and 1000 million cycles has been achieved using polycarbonate urethanes, and good resistance to degradation, calcification and thrombosis in vivo has been shown with some polysiloxane-based polyurethanes. Nevertheless, polymeric valves have remained relegated to use in temporary ventricular assist devices for bridging heart failure patients to transplantation. Some recent studies suggest that there is a greater degree of instability in thermoplastic materials than hitherto believed so that significant challenges remain in the search for the combination of durability and biocompatibility that would allow polymeric valves to become a clinical reality for surgical implantation. Perhaps more importantly, they could become candidates for use in situations where minimally invasive transcatheter procedures are used to replace diseased valves. Being amenable to relatively inexpensive mass production techniques, the attainment of this goal could benefit very large numbers of patients in developing and emerging countries who currently have no access to treatment for rheumatic heart disease that is so prevalent in these areas. This review discusses the evolution and current status of polymeric valves in wide-ranging circumstances.

Experimental study of physical properties of artificial materials for the development of the tissue-engineered valvular heart apparatus in comparison with biological analogs

NASA Astrophysics Data System (ADS)

Chiryatyeva, Aleksandra; Trebushat, Dmitry; Prokhorokhin, Aleksei; Khakhalkin, Vladimir; Andreev, Mark; Novokhreschenov, Aleksei; Kretov, Evgeny

2017-12-01

Cardiovascular diseases are the leading cause of death worldwide. Valvular heart disease often requires valve repair or replacement. Today, surgery uses xenograft—porcine or bovine pericardium. However, bioprosthetic valves do not ensure sufficient durability. We investigated 0.6% glutaraldehyde-treated porcine pericardium to define its properties. Using a tensile test stand, we studied characteristics of the polymeric material—expanded polytetrafluoroethylene (ePTFE)—and compared it to xenopericardium. The artificial material provides a better durability; it has higher elastic modulus and ultimate tensile strength. However, ePTFE samples demonstrated direction anisotropy due to extrusion features. It requires the enhancement of quality of the ePTFE sheet or investigation of other polymeric materials to find the adequate replacement for bioprosthetic heart valves.

Durable superhydrophobic carbon soot coatings for sensor applications

NASA Astrophysics Data System (ADS)

Esmeryan, K. D.; Radeva, E. I.; Avramov, I. D.

2016-01-01

A novel approach for the fabrication of durable superhydrophobic (SH) carbon soot coatings used in quartz crystal microbalance (QCM) based gas or liquid sensors is reported. The method uses modification of the carbon soot through polymerization of hexamethyldisiloxane (HMDSO) by means of glow discharge RF plasma. The surface characterization shows a fractal-like network of carbon nanoparticles with diameter of ~50 nm. These particles form islands and cavities in the nanometer range, between which the plasma polymerized hexamethyldisiloxane (PPHMDSO) embeds and binds to the carbon chains and QCM surface. Such modified surface structure retains the hydrophobic nature of the soot and enhances its robustness upon water droplet interactions. Moreover, it significantly reduces the insertion loss and dynamic resistance of the QCM compared to the commonly used carbon soot/epoxy resin approach. Furthermore, the PPHMDSO/carbon soot coating demonstrates durability and no aging after more than 40 probing cycles in water based liquid environments. In addition, the surface layer keeps its superhydrophobicity even upon thermal annealing up to 540 °C. These experiments reveal an opportunity for the development of soot based SH QCMs with improved electrical characteristics, as required for high-resolution gas or liquid measurements.

In vivo endothelial siRNA delivery using polymeric nanoparticles with low molecular weight

NASA Astrophysics Data System (ADS)

Dahlman, James E.; Barnes, Carmen; Khan, Omar F.; Thiriot, Aude; Jhunjunwala, Siddharth; Shaw, Taylor E.; Xing, Yiping; Sager, Hendrik B.; Sahay, Gaurav; Speciner, Lauren; Bader, Andrew; Bogorad, Roman L.; Yin, Hao; Racie, Tim; Dong, Yizhou; Jiang, Shan; Seedorf, Danielle; Dave, Apeksha; Singh Sandhu, Kamaljeet; Webber, Matthew J.; Novobrantseva, Tatiana; Ruda, Vera M.; Lytton-Jean, Abigail K. R.; Levins, Christopher G.; Kalish, Brian; Mudge, Dayna K.; Perez, Mario; Abezgauz, Ludmila; Dutta, Partha; Smith, Lynelle; Charisse, Klaus; Kieran, Mark W.; Fitzgerald, Kevin; Nahrendorf, Matthias; Danino, Dganit; Tuder, Rubin M.; von Andrian, Ulrich H.; Akinc, Akin; Panigrahy, Dipak; Schroeder, Avi; Koteliansky, Victor; Langer, Robert; Anderson, Daniel G.

2014-08-01

Dysfunctional endothelium contributes to more diseases than any other tissue in the body. Small interfering RNAs (siRNAs) can help in the study and treatment of endothelial cells in vivo by durably silencing multiple genes simultaneously, but efficient siRNA delivery has so far remained challenging. Here, we show that polymeric nanoparticles made of low-molecular-weight polyamines and lipids can deliver siRNA to endothelial cells with high efficiency, thereby facilitating the simultaneous silencing of multiple endothelial genes in vivo. Unlike lipid or lipid-like nanoparticles, this formulation does not significantly reduce gene expression in hepatocytes or immune cells even at the dosage necessary for endothelial gene silencing. These nanoparticles mediate the most durable non-liver silencing reported so far and facilitate the delivery of siRNAs that modify endothelial function in mouse models of vascular permeability, emphysema, primary tumour growth and metastasis.

Laundering durable antibacterial cotton fabrics grafted with pomegranate-shaped polymer wrapped in silver nanoparticle aggregations

NASA Astrophysics Data System (ADS)

Liu, Hanzhou; Lv, Ming; Deng, Bo; Li, Jingye; Yu, Ming; Huang, Qing; Fan, Chunhai

2014-08-01

To improve the laundering durability of the silver functionalized antibacterial cotton fabrics, a radiation-induced coincident reduction and graft polymerization is reported herein where a pomegranate-shaped silver nanoparticle aggregations up to 500 nm can be formed due to the coordination forces between amino group and silver and the wrapping procedure originated from the coincident growth of the silver nanoparticles and polymer graft chains. This pomegranate-shaped silver NPAs functionalized cotton fabric exhibits outstanding antibacterial activities and also excellent laundering durability, where it can inactivate higher than 90% of both E. coli and S. aureus even after 50 accelerated laundering cycles, which is equivalent to 250 commercial or domestic laundering cycles.

Polymeric thermochromic dye for improvement of asphalt pavement durability : final report.

DOT National Transportation Integrated Search

2017-01-01

Asphalt pavements features good performance and relatively low construction and maintenance : costs. However, the black color of asphalt binder implies that the sunlight is not reflected but : absorbed, which raises the temperature of the asphalt pav...

Design and testing of tubular polymeric capsules for self-healing of concrete

NASA Astrophysics Data System (ADS)

Araújo, M.; Van Tittelboom, K.; Feiteira, J.; Gruyaert, E.; Chatrabhuti, S.; Raquez, J.-M.; Šavija, B.; Alderete, N.; Schlangen, E.; De Belie, N.

2017-10-01

Polymeric healing agents have proven their efficiency to heal cracks in concrete in an autonomous way. However, the bottleneck for valorisation of self-healing concrete with polymeric healing agents is their encapsulation. In the present work, the suitability of polymeric materials such as poly(methyl methacrylate) (PMMA), polystyrene (PS) and poly(lactic acid) (PLA) as carriers for healing agents in self-healing concrete has been evaluated. The durability of the polymeric capsules in different environments (demineralized water, salt water and simulated concrete pore solution) and their compatibility with various healing agents have been assessed. Next, a numerical model was used to simulate capsule rupture when intersected by a crack in concrete and validated experimentally. Finally, two real-scale self-healing concrete beams were made, containing the selected polymeric capsules (with the best properties regarding resistance to concrete mixing and breakage upon crack formation) or glass capsules and a reference beam without capsules. The self-healing efficiency was determined after crack creation by 3-point-bending tests.

Covalent immobilization of metal–organic frameworks onto the surface of nylon—a new approach to the functionalization and coloration of textiles

PubMed Central

Yu, Ming; Li, Wanxin; Wang, Ziqiang; Zhang, Bowu; Ma, Hongjuan; Li, Linfan; Li, Jingye

2016-01-01

The prevention of refractory organic pollution caused by conventional dyeing and the development of new fabrics with various functions are two issues to be solved urgently in the field of textile fabrication. Here, we report a new environmentally friendly route for the simultaneous coloration and functionalization of textiles by the covalent immobilization of a metal–organic framework, Cr-based MIL-101(Cr), onto the surfaces of nylon fabrics by co-graft polymerization with 2-hydroxyethyl acrylate initiated by γ-ray irradiation. The Cr(III) clusters color the nylon fabric, and the color intensity varies with the MIL-101 content, providing a “green” textile coloration method that is different from conventional dyeing processes. An X-ray diffraction (XRD) analysis shows that the nanoporous structure of the original MIL-101 particles is retained during radiation-induced graft polymerization. Numerous nanopores are introduced onto the surface of the nylon fabric, which demonstrated better sustained-release-of-aroma performance versus pristine nylon fabric in tests. The modified fabrics exhibit laundering durability, with MIL-101 nanoparticles intact on the nylon surface after 30 h of dry cleaning. PMID:26948405

Next-Generation in Situ Hybridization Chain Reaction: Higher Gain, Lower Cost, Greater Durability

PubMed Central

2014-01-01

Hybridization chain reaction (HCR) provides multiplexed, isothermal, enzyme-free, molecular signal amplification in diverse settings. Within intact vertebrate embryos, where signal-to-background is at a premium, HCR in situ amplification enables simultaneous mapping of multiple target mRNAs, addressing a longstanding challenge in the biological sciences. With this approach, RNA probes complementary to mRNA targets trigger chain reactions in which metastable fluorophore-labeled RNA hairpins self-assemble into tethered fluorescent amplification polymers. The properties of HCR lead to straightforward multiplexing, deep sample penetration, high signal-to-background, and sharp subcellular signal localization within fixed whole-mount zebrafish embryos, a standard model system for the study of vertebrate development. However, RNA reagents are expensive and vulnerable to enzymatic degradation. Moreover, the stringent hybridization conditions used to destabilize nonspecific hairpin binding also reduce the energetic driving force for HCR polymerization, creating a trade-off between minimization of background and maximization of signal. Here, we eliminate this trade-off by demonstrating that low background levels can be achieved using permissive in situ amplification conditions (0% formamide, room temperature) and engineer next-generation DNA HCR amplifiers that maximize the free energy benefit per polymerization step while preserving the kinetic trapping property that underlies conditional polymerization, dramatically increasing signal gain, reducing reagent cost, and improving reagent durability. PMID:24712299

Durable silver mirror with ultra-violet thru far infra-red reflection

DOEpatents

Wolfe, Jesse D.

2010-11-23

A durable highly reflective silver mirror characterized by high reflectance in a broad spectral range of about 300 nm in the UV to the far infrared (.about.10000 nm), as well as exceptional environmental durability. A high absorptivity metal underlayer is used which prevents the formation of a galvanic cell with a silver layer while increasing the reflectance of the silver layer. Environmentally durable overcoat layers are provided to enhance mechanical and chemical durability and protect the silver layer from corrosion and tarnishing, for use in a wide variety of surroundings or climates, including harsh or extreme environments.

High Temperature Polymeric Materials for Space Transportation Propulsion Applications

NASA Technical Reports Server (NTRS)

Meador, Michael A.; Campbell, Sandi G.; Chuang, Kathy C.; Scheimann, Daniel A.; Mintz, Eric; Hylton, Donald; Veazie, David; Criss, James; Kollmansberg, Ron; Tsotsis, Tom

2003-01-01

High temperature polymer matrix composites are attractive materials for space transporation propulsion systems because of their low density and high specific strength. However, the relatively poor stability and processability of these materials can render them unsuitable for many of these applications. New polymeric materials have been developed under the Propulsion Research and Technology Program through the use of novel resin chemistry and nanotechnology. These new materials can significantly enhance the durability and weight and improve the processability and affordability of propulsion components for advanced space transportation systems.

Durability of polymer matrix composites for automotive structural applications: A state-of-the-art review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corum, J.M.; Simpson, W.A. Jr.; Sun, C.T.

1995-07-01

A key unanswered question that must be addressed before polymeric composites will be widely used in automotive structural components is their known durability. Major durability issues are the effects that cyclic loadings, creep, automotive fluid environments, and low-energy impacts have on dimensional stability, strength, and stiffness throughout the required life of a composite component. This report reviews the current state of understanding in each of these areas. It also discusses the limited information that exists on one of the prime candidate materials for automotive structural applications--an isocyanurate reinforced with a continuous strand, swirl mat. Because of the key role thatmore » nondestructive evaluations must play in understanding damage development and progression, a chapter is included on ultrasonic techniques. A final chapter then gives conclusions and recommendations for research needed to resolve the various durability issues. These recommendations will help provide a sound basis for program planning for the Durability of Lightweight Composite Structures Project sponsored by the US Department of Energy in cooperation with the Automotive Composites Consortium of Chrysler, Ford, and General Motors.« less

Synthesis of ‘reactive’ and covalent polymeric multilayer coatings with durable superoleophobic and superoleophilic properties under water† †Electronic supplementary information (ESI) available: Fig. S1–S15 accounting the growth of NC with and without the LbL deposition process, detailed comparisons of the multilayers of BPEI and NC, the change in the underwater oil-wettability with increasing deposition cycles of NC, the change in the optical transparency of the multilayers under water, the underwater oil-wettability of various model oils on post-modified multilayers of NC, bouncing of oil droplets underwater, the change in adhesive interactions with LbL deposition of NC, beading and wetting of oil droplets on post-modified multilayers under water, the effect of heating, freezing, and chemical and physical insults on the oil-wettability of the multilayers under water, LbL coating of various substrates, the guided transfer of oil droplets under water and the cleaning of oil using superoleophilic cotton under water. See DOI: 10.1039/c7sc01055a Click here for additional data file.

PubMed Central

Parbat, Dibyangana

2017-01-01

Bioinspired underwater super-oil-wettability (superoleophilic/superoleophobic) properties are emerging as a potential avenue for developing smart materials for addressing issues related to healthcare, environment, energy, etc. However, the inherent poor durability of the materials that are mostly developed using polymeric hydrogel, metal oxide coatings and electrostatic multilayers often challenges the application of these wettability properties in practical scenarios. Here, ‘amine-reactive’ polymeric multilayers of nano-complex were developed to fabricate ‘internal’ underwater superoleophobic/superoleophilic coatings with impeccable physical/chemical durability. This allows the super-wetting properties to exist beyond the surface of the material and remain intact even after severe physical damage including erosion of the material and continuous exposure to an artificial-marine environment for more than 80 days. Moreover, this current design allowed for independent revalidation of some key hypotheses with direct experimental demonstrations, and provided a basis to develop highly durable super-oil-wettability properties under water. It is believed that this contemporary study will make a worthwhile contribution on developing multifunctional materials for widespread practical applications by exploiting these super-oil-wetting properties. PMID:28989639

A high-spin and durable polyradical: poly(4-diphenylaminium-1,2-phenylenevinylene).

PubMed

Murata, Hidenori; Takahashi, Masahiro; Namba, Kazuaki; Takahashi, Naoki; Nishide, Hiroyuki

2004-02-06

A purely organic, high-spin, and durable polyradical molecule was synthesized: It is based on the non-Kekulé- and non-disjoint design of a pi-conjugated poly(1,2-phenylenevinylene) backbone pendantly 4-substituted with multiple robust arylaminium radicals. 4-N,N-Bis(4-methoxy- and -tert-butylphenyl)amino-2-bromostyrene 5 were synthesized and polymerized with a palladium-phosphine catalyst to afford the head-to-tail-linked polyradical precursors (1). Oxidation of 1 with the nitrosonium ion solubilized with a crown ether gave the aminium polyradicals (1(+)()) which were durable (half-life > 1 month) at room temperature in air. A high-spin ground state with an average S = (4.5)/2 for 1a(+) was proved even at room temperature by magnetic susceptibility, magnetization, ESR, and NMR measurements.

Low Earth orbital atomic oxygen and ultraviolet radiation effects on polymers

NASA Technical Reports Server (NTRS)

Dever, Joyce A.

1991-01-01

Because atomic oxygen and solar ultraviolet radiation present in the low earth orbital (LEO) environment can alter the chemistry of polymers resulting in degradation, their effects and mechanisms of degradation must be determined in order to determine the long term durability of polymeric surfaces to be exposed on missions such as Space Station Freedom. The effects of atomic oxygen on polymers which contain protective coatings must also be explored, since unique damage mechanisms can occur in areas where the protective coatings has failed. Mechanisms can be determined by utilizing results from previous LEO missions, by performing ground based LEO simulation tests and analysis, and by carrying out focussed space experiments. A survey is presented of the interactions and possible damage mechanisms for environmental atomic oxygen and UV radiation exposure of polymers commonly used in LEO.

Polymeric trileaflet prosthetic heart valves: evolution and path to clinical reality

PubMed Central

Claiborne, Thomas E; Slepian, Marvin J; Hossainy, Syed; Bluestein, Danny

2013-01-01

Present prosthetic heart valves, while hemodynamically effective, remain limited by progressive structural deterioration of tissue valves or the burden of chronic anticoagulation for mechanical valves. An idealized valve prosthesis would eliminate these limitations. Polymeric heart valves (PHVs), fabricated from advanced polymeric materials, offer the potential of durability and hemocompatibility. Unfortunately, the clinical realization of PHVs to date has been hampered by findings of in vivo calcification, degradation and thrombosis. Here, the authors review the evolution of PHVs, evaluate the state of the art of this technology and propose a pathway towards clinical reality. In particular, the authors discuss the development of a novel aortic PHV that may be deployed via transcatheter implantation, as well as its optimization via device thrombogenicity emulation. PMID:23249154

Cold Regions Environmental Protection and Durability Test of Clothing.

DTIC Science & Technology

1983-07-08

17 AD-A130 482 COLD REGIONS ENVIRONMENTAL PROTECTION AND DURABILITY 1 / TEST OF CLDTHING(U) *ARMY TEST AND EVALGATION COMMAND ABERDEEN PROVING GROUND...MD 08 JUL 83 TOP-10-2510 UNCLASSIFIED FDA 6/7 -Lm U= 1,2 2 340 12.0IIHI . 1 L1.8 j$jfLi25 .411 .6 MICROCOPY RESOLUTION TEST CHART NT’NL BUREAU C’ N j...July 1983 AD NO. COLD REGIONS ENVIRONMENTAL PROTECTION AND DURABILITY TEST OF CLOTHING Page 1 SCOPE .................................. 1 2 FACILITIES

PLASMA POLYMER FILMS AS ADHESION PROMOTING PRIMERS FOR ALUMINUM. PART II: STRENGTH AND DURABILITY OF LAP JOINTS

EPA Science Inventory

Plasma polymerized hexamethyldisiloxane (HMDSO) films (~800 A in thickness) were deposited onto 6111-T4 aluminum substrates in radio frequency and microwave powered reactors and used as primers for structural adhesive bonding. Processing variables such as substrate pre-treatment,...

Chitin Nanofibers Extracted from Crab Shells in Broadband Visible Antireflection Coatings with Controlling Layer-by-Layer Deposition and the Application for Durable Antifog Surfaces.

PubMed

Manabe, Kengo; Tanaka, Chie; Moriyama, Yukari; Tenjimbayashi, Mizuki; Nakamura, Chiaki; Tokura, Yuki; Matsubayashi, Takeshi; Kyung, Kyu-Hong; Shiratori, Seimei

2016-11-23

Reflection from various surfaces of many optical systems, such as photovoltaics and displays, is a critical issue for their performance, and antireflection coatings play a pivotal role in a wide variety of optical technologies, reducing light reflectance loss and hence maximizing light transmission. With the current movement toward optically transparent polymeric media and coatings for antireflection technology, the need for economical and environmentally friendly materials and methods without dependence on shape or size has clearly been apparent. Herein, we demonstrate novel antireflection coatings composed of chitin nanofibers (CHINFs), extracted from crab shell as a biomass material through an aqueous-based layer-by-layer self-assembly process to control the porosity. Increasing the number of air spaces inside the membrane led low refractive index, and precise control of refractive index derived from the stacking of the CHINFs achieved the highest transmittance with investigating the surface structure and the refractive index depending on the solution pH. At a wavelength of 550 nm, the transmittance of the coatings was 96.4%, which was 4.8% higher than that of a glass substrate, and their refractive index was 1.30. Further critical properties of the films were the durability and the antifogging performance derived from the mechanical stability and hydrophilicity of CHINFs, respectively. The present study may contribute to a development of systematically designed nanofibrous films which are suitable for optical applications operating at a broadband visible wavelength with durability and antifog surfaces.

Fluid dynamic characterization of a polymeric heart valve prototype (Poli-Valve) tested under continuous and pulsatile flow conditions.

PubMed

De Gaetano, Francesco; Serrani, Marta; Bagnoli, Paola; Brubert, Jacob; Stasiak, Joanna; Moggridge, Geoff D; Costantino, Maria Laura

2015-11-01

Only mechanical and biological heart valve prostheses are currently commercially available. The former show longer durability but require anticoagulant therapy; the latter display better fluid dynamic behavior but do not have adequate durability. New Polymeric Heart Valves (PHVs) could potentially combine the hemodynamic properties of biological valves with the durability of mechanical valves. This work presents a hydrodynamic evaluation of 2 groups of newly developed supra-annular, trileaflet prosthetic heart valves made from styrenic block copolymers (SBC): Poli-Valves. 2 types of Poli-Valves made of SBC and differing in polystyrene fraction content were tested under continuous and pulsatile flow conditions as prescribed by ISO 5840 Standard. A pulse duplicator designed ad hoc allowed the valve prototypes to be tested at different flow rates and frequencies. Pressure and flow were recorded; pressure drops, effective orifice area (EOA), and regurgitant volume were computed to assess the behavior of the valve. Both types of Poli-Valves met the minimum requirements in terms of regurgitation and EOA as specified by the ISO 5840 Standard. Results were compared with 5 mechanical heart valves (MHVs) and 5 tissue heart valves (THVs), currently available on the market. Based on these results, PHVs based on styrenic block copolymers, as are Poli-Valves, can be considered a promising alternative for heart valve replacement in the near future.

Prediction of In-Space Durability of Protected Polymers Based on Ground Laboratory Thermal Energy Atomic Oxygen

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; deGroh, Kim K.; Rutledge, Sharon; DiFilippo, Frank J.

1996-01-01

The probability of atomic oxygen reacting with polymeric materials is orders of magnitude lower at thermal energies (greater than O.1 eV) than at orbital impact energies (4.5 eV). As a result, absolute atomic oxygen fluxes at thermal energies must be orders of magnitude higher than orbital energy fluxes, to produce the same effective fluxes (or same oxidation rates) for polymers. These differences can cause highly pessimistic durability predictions for protected polymers and polymers which develop protective metal oxide surfaces as a result of oxidation if one does not make suitable calibrations. A comparison was conducted of undercut cavities below defect sites in protected polyimide Kapton samples flown on the Long Duration Exposure Facility (LDEF) with similar samples exposed in thermal energy oxygen plasma. The results of this comparison were used to quantify predicted material loss in space based on material loss in ground laboratory thermal energy plasma testing. A microindent hardness comparison of surface oxidation of a silicone flown on the Environmental Oxygen Interaction with Materials-III (EOIM-III) experiment with samples exposed in thermal energy plasmas was similarly used to calibrate the rate of oxidation of silicone in space relative to samples in thermal energy plasmas exposed to polyimide Kapton effective fluences.

Durability Characterization of Advanced Polymeric Composites at Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Gates, T. S.

2001-01-01

The next generation of reusable launch vehicles will require technology development in several key areas. Of these key areas, the development of polymeric composite cryogenic fuel tanks promises to present one of the most difficult technical challenges. It is envisioned that a polymer matrix composite (PMC) tank would be a large shell structure capable of containing cryogenic fuels and carrying a range of structural loads. The criteria that will be imposed on such a design include reduced weight, conformal geometry, and impermeability. It is this last criterion, impermeability, that will provide the focus of this paper. The essence of the impermeability criterion is that the tank remains leak free throughout its design lifetime. To address this criterion, one of the first steps is to conduct a complete durability assessment of the PMC materials. At Langley Research Center, a durability assessment of promising new polyimide-based PMCs is underway. This durability program has focused on designing a set of critical laboratory experiments that will determine fundamental material properties under combined thermal-mechanical loading at cryogenic temperatures. The test program provides measurements of lamina and laminate properties, including strength, stiffness, and fracture toughness. The performance of the PMC materials is monitored as a function of exposure conditions and aging time. Residual properties after exposure are measured at cryogenic temperatures and provide quantitative values of residual strength and stiffness. Primary degradation mechanisms and the associated damage modes are measured with both destructive and nondestructive techniques. In addition to mechanical properties, a range of physical properties, such as weight, glass transition, and crack density, are measured and correlated with the test conditions. This paper will report on the progress of this research program and present critical results and illustrative examples of current findings.

Environmental durability of ceramics and ceramic composites

NASA Technical Reports Server (NTRS)

Fox, Dennis S.

1992-01-01

An account is given of the current understanding of the environmental durability of both monolithic ceramics and ceramic-matrix composites, with a view to the prospective development of methods for the characterization, prediction, and improvement of ceramics' environmental durability. Attention is given to the environmental degradation behaviors of SiC, Si3N4, Al2O3, and glass-ceramic matrix compositions. The focus of corrosion prevention in Si-based ceramics such as SiC and Si3N4 is on the high and low sulfur fuel combustion-product effects encountered in heat engine applications of these ceramics; sintering additives and raw material impurities are noted to play a decisive role in ceramics' high temperature environmental response.

Durability and CMAS Resistance of Advanced Environmental Barrier Coatings Systems for SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2015-01-01

Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. This paper will emphasize advanced environmental barrier coating developments for SiCSiC turbine airfoil components, by using advanced coating compositions and processing, in conjunction with mechanical and environment testing and durability validations. The coating-CMC degradations and durability in the laboratory simulated engine fatigue-creep and complex operating environments are being addressed. The effects of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the degradation mechanisms of the environmental barrier coating systems will be discussed. The results help understand the advanced EBC-CMC system performance, aiming at the durability improvements of more robust, prime-reliant environmental barrier coatings for successful applications of the component technologies and lifing methodologies.

Development of PLA hybrid yarns for biobased self-reinforced polymer composites

NASA Astrophysics Data System (ADS)

Köhler, T.; Gries, T.; Seide, G.

2017-10-01

Lightweight materials are a necessity in various industries. Lightweight design is in the key interest of the mobility sector, e.g. the automotive and aerospace industry. This trend applies also for the consumer industries, e.g. sporting goods. In addition, the worldwide demand for replacing fossil-based materials has led to a significant growth of bioplastics. Due to their low mechanical performance and durability, their use is still limited. Therefore, it is necessary to develop biobased, sustainable polymeric materials with high stiffness, high impact and high durability without impairing recyclability at a similar price level of non-biobased solutions. Biobased self-reinforced polymer composites offer these unique properties.

Flexible polymeric rib waveguide with self-align couplers system

PubMed Central

Huang, Cheng-Sheng; Wang, Wei-Chih

2011-01-01

The authors report a polymeric based rib waveguide with U shape self-align fiber couplers system using a simple micromolding process with SU8 as a molding material and polydimethysiloxane as a waveguide material. The material is used for its good optical transparency, low surface tension, biocompatibility, and durability. Furthermore, the material is highly formable. This unique fabrication molding technique provides a means of keeping the material and manufacturing costs to a minimum. The self-align fiber couplers system also proves a fast and simple means of light coupling. The flexible nature of the waveguide material makes this process ideal for a potential wearable optical sensor. PMID:22171151

Environmental Stability and Oxidation Behavior of HfO2-Si and YbGd(O) Based Environmental Barrier Coating Systems for SiCSiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Farmer, Serene; McCue, Terry R.; Harder, Bryan; Hurst, Janet B.

2017-01-01

Ceramic environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiCSiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, environmental durable environmental barrier coating systems. In this paper, the durability and performance of advanced Electron Beam-Physical Vapor Deposition (EB-PVD) NASA HfO2-Si and YbGdSi(O) EBC bond coat top coat systems for SiCSiC CMC have been summarized. The high temperature thermomechanical creep, fatigue and oxidation resistance have been investigated in the laboratory simulated high-heat-flux environmental test conditions. The advanced NASA EBC systems showed promise to achieve 1500C temperature capability, helping enable next generation turbine engines with significantly improved engine component temperature capability and durability.

Combined Thermomechanical and Environmental Durability of Environmental Barrier Coating Systems on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna

2016-01-01

Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) will play a crucial role in next generation turbine engines for hot-section component applications. The development of prime-reliant environmental barrier coatings is essential to the EBC-CMC system durability, ensuring the successful implementations of the high temperature and lightweight engine component technologies for engine applications.This paper will emphasize recent NASA environmental barrier coating and CMC developments for SiC/SiC turbine airfoil components, utilizing advanced coating compositions and processing methods. The emphasis has been particularly placed on thermomechanical and environment durability evaluations of EBC-CMC systems. We have also addressed the integration of the EBCs with advanced SiC/SiC CMCs, and studied the effects of combustion environments and Calcium-Magnesium-Alumino-Silicate (CMAS) deposits on the durability of the EBC-CMC systems under thermal gradient and mechanical loading conditions. Advanced environmental barrier coating systems, including multicomponent rare earth silicate EBCs and HfO2-Si based bond coats, will be discussed for the performance improvements to achieve better temperature capability and CMAS resistance for future engine operating conditions.

Occurrence and Speciation of Polymeric Chromium(III), Monomeric Chromium(III) and Chromium(VI) in Environmental Samples

PubMed Central

HU, LIGANG; CAI, YONG; JIANG, GUIBIN

2016-01-01

Laboratory experiments suggest that polymeric Cr(III) could exist in aqueous solution for a relative long period of time. However, the occurrence of polymeric Cr(III) has not been reported in environmental media due partially to the lack of method for speciating polymeric Cr. We observed an unknown Cr species during the course of study on speciation of Cr in the leachates of chromated-copper-arsenate (CCA)-treated wood. Efforts were made to identify structure of the unknown Cr species. Considering the forms of Cr existed in the CCA-treated woods, we mainly focused our efforts to determine if the unknown species were polymeric Cr(III), complex of Cr/As or complex of Cr with dissolved organic matter (DOM). In order to evaluate whether polymeric Cr(III) largely exist in wood leachates, high performance liquid chromatography coupled with inductively coupled mass spectrometry (HPLC-ICPMS was used) for simultaneous speciation of monomeric Cr(III), polymeric Cr(III), and Cr(VI). In addition to wood leachates where polymeric Cr (III) ranged from 39.1 to 67.4 %, occurrence of the unknown Cr species in other environmental matrices, including surface waters, tap and waste waters, was also investigated. It was found that polymeric Cr(III) could exist in environmental samples containing μg/L level of Cr, at a level up to 60% of total Cr, suggesting that polymeric Cr(III) could significantly exist in natural environments. Failure in quantifying polymeric Cr(III) would lead to the underestimation of total Cr and bias in Cr speciation. The environmental implication of the presence of polymeric Cr(III) species in the environment deserves further study. PMID:27156211

Failure of structural elements made of polymer supported composite materials during the multiyear natural aging

NASA Astrophysics Data System (ADS)

Blinkov, Pavel; Ogorodov, Leonid; Grabovyy, Peter

2018-03-01

Modern high-rise construction introduces a number of limitations and tasks. In addition to durability, comfort and profitability, projects should take into account energy efficiency and environmental problems. Polymer building materials are used as substitutes for materials such as brick, concrete, metal, wood and glass, and in addition to traditional materials. Plastic materials are light, can be formed into complex shapes, durable and low, and also possess a wide range of properties. Plastic materials are available in various forms, colors and textures and require minimal or no color. They are resistant to heat transfer and diffusion of moisture and do not suffer from metal corrosion or microbial attack. Polymeric materials, including thermoplastics, thermoset materials and wood-polymer composites, have many structural and non-structural applications in the construction industry. They provide unique and innovative solutions at a low cost, and their use is likely to grow in the future. A number of polymer composite materials form complex material compositions, which are applied in the construction in order to analyze the processes of damage accumulation under the conditions of complex nonstationary loading modes, and to determine the life of structural elements considering the material aging. This paper present the results of tests on short-term compression loading with a deformation rate of v = 2 mm/min using composite samples of various shapes and sizes.

The Development of 2700-3000 F Environmental Barrier Coatings for SiC/SiC Ceramic Matrix Composites: Challenges and Opportunities

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2015-01-01

Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in future turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is a key to enable the applications of the envisioned 2700-3000F EBC - CMC systems to help achieve next generation engine performance and durability goals. This paper will primarily address the performance requirements and design considerations of environmental barrier coatings for turbine engine applications. The emphasis is placed on current NASA candidate environmental barrier coating systems for SiCSiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. The efforts have been also directed to developing prime-reliant, self-healing 2700F EBC bond coat; and high stability, lower thermal conductivity, and durable EBC top coats. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, cyclic durability, erosion-impact resistance, and long-term system performance will be described. The research and development opportunities for turbine engine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be discussed.

Acyclic N-Halamine Polymeric Biocidal Films

DTIC Science & Technology

2010-07-01

surfaces were rechargeable upon chlorine loss. antimicrobial, bacteria, biocidal coatings, biofilms , N-halamine U U U UU 14 Joe Wander 850 283-6240...halamine, biofilms , antimicrobial. INTRODUCTION A variety of antimicrobial organic materials, including phosp ho- nium salts [1-4], quaternary ammonium...Cotton Cellulose , J. Appl. Polym. Sci., 81: 617-624. 21. Sun, Y. and Sun, G. (2002). Durable and Regenerable Antimicrobial Textile Materials Prepared

Aquaporin-Based Biomimetic Polymeric Membranes: Approaches and Challenges

PubMed Central

Habel, Joachim; Hansen, Michael; Kynde, Søren; Larsen, Nanna; Midtgaard, Søren Roi; Jensen, Grethe Vestergaard; Bomholt, Julie; Ogbonna, Anayo; Almdal, Kristoffer; Schulz, Alexander; Hélix-Nielsen, Claus

2015-01-01

In recent years, aquaporin biomimetic membranes (ABMs) for water separation have gained considerable interest. Although the first ABMs are commercially available, there are still many challenges associated with further ABM development. Here, we discuss the interplay of the main components of ABMs: aquaporin proteins (AQPs), block copolymers for AQP reconstitution, and polymer-based supporting structures. First, we briefly cover challenges and review recent developments in understanding the interplay between AQP and block copolymers. Second, we review some experimental characterization methods for investigating AQP incorporation including freeze-fracture transmission electron microscopy, fluorescence correlation spectroscopy, stopped-flow light scattering, and small-angle X-ray scattering. Third, we focus on recent efforts in embedding reconstituted AQPs in membrane designs that are based on conventional thin film interfacial polymerization techniques. Finally, we describe some new developments in interfacial polymerization using polyhedral oligomeric silsesquioxane cages for increasing the physical and chemical durability of thin film composite membranes. PMID:26264033

Advanced Environmental Barrier Coating and SA Tyrannohex SiC Composites Integration for Improved Thermomechanical and Environmental Durability

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Halbig, Michael; Singh, Mrityunjay

2018-01-01

The development of 2700 degF capable environmental barrier coating (EBC) systems, particularly, the Rare Earth "Hafnium" Silicon bond coat systems, have significantly improved the temperature capability and environmental stability of SiC/SiC Ceramic Matrix Composite Systems. We have specifically developed the advanced 2700 degF EBC systems, integrating the EBC to the high temperature SA Tyrannohex SiC fiber composites, for comprehensive performance and durability evaluations for potential turbine engine airfoil component applications. The fundamental mechanical properties, environmental stability and thermal gradient cyclic durability performance of the EBC - SA Tyrannohex composites were investigated. The paper will particularly emphasize the high pressure combustion rig recession, cyclic thermal stress resistance and thermomechanical low cycle fatigue testing of uncoated and environmental barrier coated Tyrannohex SiC SA composites in these simulated turbine engine combustion water vapor, thermal gradients, and mechanical loading conditions. We have also investigated high heat flux and flexural fatigue degradation mechanisms, determined the upper limits of operating temperature conditions for the coated SA composite material systems in thermomechanical fatigue conditions. Recent progress has also been made by using the self-healing rare earth-silicon based EBCs, thus enhancing the SA composite hexagonal fiber columns bonding for improved thermomechanical and environmental durability in turbine engine operation environments. More advanced EBC- composite systems based on the new EBC-Fiber Interphases will also be discussed.

The Development of Environmental Barrier Coatings for SiCSiC Ceramic Matrix Composites: Challenges and Opportunities

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2014-01-01

Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) systems will play a crucial role in future turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is a key to enable the applications of the envisioned CMC components to help achieve next generation engine performance and durability goals. This paper will primarily address the performance requirements and design considerations of environmental barrier coatings for turbine engine applications. The emphasis is placed on current candidate environmental barrier coating systems for SiCSiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. Major technical barriers in developing advanced environmental barrier coating systems, the coating integrations with next generation CMC turbine components having improved environmental stability, cyclic durability and system performance will be described. The development trends for turbine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be discussed.

Durability Issues for the Protection of Materials from Atomic Oxygen Attack in Low Earth Orbit

NASA Technical Reports Server (NTRS)

Banks, Bruce; Lenczewski, Mary; Demko, Rikako

2002-01-01

Low Earth orbital atomic oxygen is capable of eroding most polymeric materials typically used on spacecraft. Solar array blankets, thermal control polymers, and carbon fiber matrix composites are readily oxidized to become thinner and less capable of supporting the loads imposed upon them. Protective coatings have been developed that are durable to atomic oxygen to prevent oxidative erosion of the underlying polymers. However, the details of the surface roughness, coating defect density, and coating configuration can play a significant role as to whether or not the coating provides long duration atomic oxygen protection. Identical coatings on different surface roughness surfaces can have drastically different durability results. Examples and analysis of the causes of resultant differences in atomic oxygen protection are presented. Implications based on in-space experiences, ground laboratory testing, and computational modeling indicate that thin film vacuum-deposited aluminum protective coatings offer much less atomic oxygen protection than sputter-deposited silicon dioxide coatings.

Materials for Concentrator Photovoltaic Systems: Optical Properties and Solar Radiation Durability

NASA Astrophysics Data System (ADS)

French, R. H.; Rodríguez-Parada, J. M.; Yang, M. K.; Lemon, M. F.; Romano, E. C.; Boydell, P.

2010-10-01

Concentrator photovoltaic (CPV) systems are designed to operate over a wide range of solar concentrations, from low concentrations of ˜1 to 12 Suns to medium concentrations in the range from 12 to 200 Suns, to high concentration CPV systems going up to 2000 Suns. Many transparent optical materials are used for a wide variety of functions ranging from refractive and reflective optics to homogenizers, encapsulants and even thermal management. The classes of materials used also span a wide spectrum from hydrocarbon polymers (HCP) and fluoropolymers (FP) to silicon containing polymers and polyimides (PI). The optical properties of these materials are essential to the optical behavior of the system. At the same time radiation durability of these materials under the extremely wide range of solar concentrations is a critical performance requirement for the required lifetime of a CPV system. As part of our research on materials for CPV we are evaluating the optical properties and solar radiation durability of various polymeric materials to define the optimum material combinations for various CPV systems.

Durable flame retardant and antibacterial finishing on cotton fabrics with cyclotriphosphazene/polydopamine/silver nanoparticles hybrid coatings

NASA Astrophysics Data System (ADS)

Li, Yingzhan; Wang, Bijia; Sui, Xiaofeng; Xie, Ruyi; Xu, Hong; Zhang, Linping; Zhong, Yi; Mao, Zhiping

2018-03-01

Durable flame retardant and antibacterial hybrid coatings were developed for cotton fabrics via simultaneous polymerization of dopamine and hydrolytic condensation of N3P3[NH(CH2)3Si(OC2H5)3]6. Silver nanoparticles were also introduced to the coatings by in situ reaction of AgNO3 with catechol moieties on polydopamine (PDA) in the absence of any external reducing agents. Energy dispersive spectrometer (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were employed to study the morphology and constitution of the coatings. Thermal stability and combustion behaviors were characterized with thermogravimetric analysis (TGA) and vertical flammability tests. Considerable flame retardancy was obtained for the modified cotton fabrics, which also exhibited decent antibacterial activities (99.99%) against Gram-positive bacteria S. aureus and Gram-negative bacteria E. coli. The modification was durable with largely intact flame retardancy and antimicrobial properties after 30 washing cycles.

Development of Advanced Environmental Barrier Coatings for SiC/SiC Composites at NASA GRC: Prime-Reliant Design and Durability Perspectives

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2017-01-01

Environmental barrier coatings (EBCs) are considered technologically important because of the critical needs and their ability to effectively protect the turbine hot-section SiC/SiC ceramic matrix composite (CMC) components in harsh engine combustion environments. The development of NASA's advanced environmental barrier coatings have been aimed at significantly improved the coating system temperature capability, stability, erosion-impact, and CMAS resistance for SiC/SiC turbine airfoil and combustors component applications. The NASA environmental barrier coating developments have also emphasized thermo-mechanical creep and fatigue resistance in simulated engine heat flux and environments. Experimental results and models for advanced EBC systems will be presented to help establishing advanced EBC composition design methodologies, performance modeling and life predictions, for achieving prime-reliant, durable environmental coating systems for 2700-3000 F engine component applications. Major technical barriers in developing environmental barrier coating systems and the coating integration with next generation composites having further improved temperature capability, environmental stability, EBC-CMC fatigue-environment system durability will be discussed.

Carbon Nanotube/Conductive Additive/Space Durable Polymer Nanocomposite Films for Electrostatic Charge Dissipation

NASA Technical Reports Server (NTRS)

Smith, Joseph G., Jr.; Watson, Kent A.; Delozier, Donavon M.; Connell, John W.

2003-01-01

Thin film membranes of space environmentally stable polymeric materials possessing low color/solar absorptivity (alpha) are of interest for potential applications on Gossamer spacecraft. In addition to these properties, sufficient electrical conductivity is required in order to dissipate electrostatic charge (ESC) build-up brought about by the charged orbital environment. One approach to achieve sufficient electrical conductivity for ESC mitigation is the incorporation of single wall carbon nanotubes (SWNTs). However, when the SWNTs are dispersed throughout the polymer matrix, the nanocomposite films tend to be significantly darker than the pristine material resulting in a higher alpha. The incorporation of conductive additives in combination with a decreased loading level of SWNTs is one approach for improving alpha while retaining conductivity. Taken individually, the low loading level of conductive additives and SWNTs is insufficient in achieving the percolation level necessary for electrical conductivity. When added simultaneously to the film, conductivity is achieved through a synergistic effect. The chemistry, physical, and mechanical properties of the nanocomposite films will be presented.

NiCrNx interlayer thickness dependence of spectral performance and environmental durability of protected-silver mirrors

NASA Astrophysics Data System (ADS)

Xu, Xu; Li, Bincheng; He, Wenyan; Wang, Changjun; Wei, Ming

2018-04-01

Gemini-style protected-silver mirror (Sub / NiCrNx / Ag / NiCrNx / SiNx / Air) is a suitable choice for optical instruments requiring both long-term environmental durability and high broadband reflectance. Three Gemini-style protected-silver mirrors with NiCrNx interlayer thicknesses between 0.1 and 0.6 nm were prepared by magnetron sputtering, and the dependences of spectral properties and environmental durability of these protected-silver mirrors on the thickness of NiCrNx interlayer between the silver layer and SiNx layer were investigated in-depth. The reflectance, transmittance and total scattering loss measurements, optical microscope, and scanning electron microscope imaging were employed to characterize the spectral properties and surface morphology, and accelerated environmental tests, including humidity test and salt fog test, were applied to investigate the environmental durability. The experimental results showed that both optical and corrosion-resistant properties of protected-silver mirrors were NiCrNx interlayer thickness dependent, and an optimum NiCrNx interlayer thickness should be ˜0.3 nm for Gemini-style protected-silver mirrors to have reasonably both high reflectance in a broadband spectral range from visible to far infrared and good corrosion resistance for long-lifetime applications in harsh environments.

Durability and Design Issues of Thermal/environmental Barrier Coatings on Sic/sic Ceramic Matrix Composites Under 1650 C Test Conditions

NASA Technical Reports Server (NTRS)

Zhu, Dong-Ming; Choi, Sung R.; Ghosn, Louis J.; Miller, Robert A.

2004-01-01

Ceramic thermal/environmental barrier coatings for SiC-based ceramics will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating durability remains a major concern with the ever-increasing temperature requirements. Currently, advanced T/EBC systems, which typically include a high temperature capable zirconia- (or hahia-) based oxide top coat (thermal barrier) on a less temperature capable mullite/barium-strontium-aluminosilicate (BSAS)/Si inner coat (environmental barrier), are being developed and tested for higher temperature capability Sic combustor applications. In this paper, durability of several thermal/environmental barrier coating systems on SiC/SiC ceramic matrix composites was investigated under laser simulated engine thermal gradient cyclic, and 1650 C (3000 F) test conditions. The coating cracking and delamination processes were monitored and evaluated. The effects of temperature gradients and coating configurations on the ceramic coating crack initiation and propagation were analyzed using finite element analysis (FEA) models based on the observed failure mechanisms, in conjunction with mechanical testing results. The environmental effects on the coating durability will be discussed. The coating design approach will also be presented.

High Pressure Burner Rig Testing of Advanced Environmental Barrier Coatings for Si3N4 Turbine Components

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Fox, Dennis S.; Pastel, Robert T.

2007-01-01

Advanced thermal and environmental barrier coatings are being developed for Si3N4 components for turbine engine propulsion applications. High pressure burner rig testing was used to evaluate the coating system performance and durability. Test results demonstrated the feasibility and durability of the coating component systems under the simulated engine environments.

Environmental Barrier Coating Development for SiC/SiC Ceramic Matrix Composites: Recent Advances and Future Directions

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2016-01-01

This presentation briefly reviews the SiC/SiC major environmental and environment-fatigue degradations encountered in simulated turbine combustion environments, and thus NASA environmental barrier coating system evolution for protecting the SiC/SiC Ceramic Matrix Composites for meeting the engine performance requirements. The presentation will review several generations of NASA EBC materials systems, EBC-CMC component system technologies for SiC/SiC ceramic matrix composite combustors and turbine airfoils, highlighting the temperature capability and durability improvements in simulated engine high heat flux, high pressure, high velocity, and with mechanical creep and fatigue loading conditions. This paper will also focus on the performance requirements and design considerations of environmental barrier coatings for next generation turbine engine applications. The current development emphasis is placed on advanced NASA candidate environmental barrier coating systems for SiC/SiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. The efforts have been also directed to developing prime-reliant, self-healing 2700F EBC bond coat; and high stability, lower thermal conductivity, and durable EBC top coats. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, erosion-impact resistance, and long-term fatigue-environment system durability performance will be described. The research and development opportunities for turbine engine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be briefly discussed.

Organic monolith frits encased in polyether ether ketone tubing with improved durability for liquid chromatography.

PubMed

Park, Sin Young; Cheong, Won Jo

2015-09-01

This study introduces a preparation method for polymer-encased monolith frits with improved durability for liquid chromatography columns. The inner surface of the polyether ether ketone tubing is pretreated with sulfuric acid in the presence of catalysts (vanadium oxide and sodium sulfate). The tubing was rinsed with water and acetone, flushed with nitrogen, and treated with glycidyl methacrylate. After washing, the monolith reaction mixture composed of lauryl methacrylate, ethylene glycol dimethacrylate, initiator, and porogenic solvent was filled in the tubing and subjected to in situ polymerization. The tubing was cut into thin slices and used as frits for microcolumns. To check their durability, the frit slices were placed in a vial and a heavy impact was applied on the vial by a vortex mixer for various periods. The frits made in the presence of catalysts were found to be more durable than those made without catalysts. Furthermore, when the monolith-incorporated tubing was used as a chromatography column, the column prepared in the presence of catalysts resulted in a better separation efficiency. The separation performance of the columns installed with the polyether ether ketone encased monolith frits was comparable to that of the columns installed with the commercial stainless-steel screen frits. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of commercial aircraft operating environment on composite materials

NASA Technical Reports Server (NTRS)

Chapman, A. J.; Hoffman, D. J.; Hodges, W. T.

1980-01-01

Long term effects of commercial aircraft operating environment on the properties and durability of composite materials are being systematically explored. Composite specimens configured for various mechanical property tests are exposed to environmental conditions on aircraft in scheduled airline service, on racks at major airports, and to controlled environmental conditions in the laboratory. Results of tests following these exposures will identify critical parameters affecting composite durability, and correlation of the data will aid in developing methods for predicting durability. Interim results of these studies show that mass change of composite specimens on commercial aircraft depends upon the regional climate and season, and that mass loss from composite surfaces due to ultraviolet radiation can be largely prevented by aircraft paint.

Effects of chloride additives on the mechanical stability and environmental durability of porous MgF2 thin films

NASA Astrophysics Data System (ADS)

Schütz, F.; Scheurell, K.; Scholz, G.; Kemnitz, E.

2016-09-01

Porous antireflective thin films, prepared of nanoscopic MgF2 sols, exhibit a low refraction index and are useful for various optical applications. Due to their porosity, film stability and durability suffer from mechanical abrasion and water solubility, respectively. Hence, we present approaches of improved mechanical stability of MgF2 layers induced by chloride addition. Antireflective (AR) films were produced by dip-coating followed by thermal treatment. Afterwards, film stability and environmental durability was strained by crockmeter and water stability tests, respectively. In comparison to films prepared from chloride-free MgF2 sols, chloride mingled sols form coatings with increased mechanical stability and a lower solubility.

Prediction of glass durability as a function of environmental conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jantzen, C M

1988-01-01

A thermodynamic model of glass durability is applied to natural, ancient, and nuclear waste glasses. The durabilities of over 150 different natural and man-made glasses, including actual ancient Roman and Islamic glasses (Jalame ca. 350 AD, Nishapur 10-11th century AD and Gorgon 9-11th century AD), are compared. Glass durability is a function of the thermodynamic hydration free energy, ..delta..G/sub hyd/, which can be calculated from glass composition and solution pH. The durability of the most durable nuclear waste glasses examined was /approximately/10/sup 6/ years. The least durable waste glass formulations were comparable in durability to the most durable simulated medievalmore » window glasses of /approximately/10/sup 3/ years. In this manner, the durability of nuclear waste glasses has been interpolated to be /approximately/10/sup 6/ years and no less than 10/sup 3/ years. Hydration thermodynamics have been shown to be applicable to the dissolution of glass in various natural environments. Groundwater-glass interactions relative to geologic disposal of nuclear waste, hydration rind dating of obsidians, andor other archeological studies can be modeled, e.g., the relative durabilities of six simulated medieval window glasses have been correctly predicted for both laboratory (one month) and burial (5 years) experiments. Effects of solution pH on glass dissolution has been determined experimentally for the 150 different glasses and can be predicted theoretically by hydration thermodynamics. The effects of solution redox on dissolution of glass matrix elements such as SI and B have shown to be minimal. The combined effects of solution pH and Eh have been described and unified by construction of thermodynamically calculated Pourbaix (pH-Eh) diagrams for glass dissolution. The Pourbaix diagrams have been quantified to describe glass dissolution as a function of environmental conditions by use of the data derived from hydration thermodynamics. 56 refs., 7 figs.« less

Microstructure Evolution and Durability of Advanced Environmental Barrier Coating Systems for SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Evans, Laura J.; McCue, Terry R.; Harder, Bryan

2016-01-01

Environmental barrier coated SiC-SiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. Advanced HfO2 and rare earth silicate environmental barrier coatings (EBCs), along with multicomponent hafnium and rare earth silicide EBC bond coats have been developed. The coating degradation mechanisms in the laboratory simulated engine thermal cycling, and fatigue-creep operating environments are also being investigated. This paper will focus on the microstructural and compositional evolutions of an advanced environmental barrier coating system on a SiC-SiC CMC substrate during the high temperature simulated durability tests, by using a Field Emission Gun Scanning Electron Microscopy, Energy Dispersive Spectroscopy (EDS) and Wavelength Dispersive Spectroscopy (WDS). The effects of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the degradation mechanisms of the environmental barrier coating systems will also be discussed. The detailed analysis results help understand the EBC-CMC system performance, aiming at the durability improvements to achieve more robust, prime-reliant environmental barrier coatings.

Advanced Environmental Barrier Coating Development for SiC/SiC Ceramic Matrix Composites: NASA's Perspectives

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2016-01-01

This presentation reviews NASA environmental barrier coating (EBC) system development programs and the coating materials evolutions for protecting the SiC/SiC Ceramic Matrix Composites in order to meet the next generation engine performance requirements. The presentation focuses on several generations of NASA EBC systems, EBC-CMC component system technologies for SiC/SiC ceramic matrix composite combustors and turbine airfoils, highlighting the temperature capability and durability improvements in simulated engine high heat flux, high pressure, high velocity, and with mechanical creep and fatigue loading conditions. The current EBC development emphasis is placed on advanced NASA 2700F candidate environmental barrier coating systems for SiC/SiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, erosion-impact resistance, and long-term fatigue-environment system durability performance are described. The research and development opportunities for advanced turbine airfoil environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling are discussed.

Polymerization- and Solvent-Induced Phase Separation in Hydrophilic-rich Dentin Adhesive Mimic

PubMed Central

Abedin, Farhana; Ye, Qiang; Good, Holly J; Parthasarathy, Ranganathan; Spencer, Paulette

2014-01-01

Current dental resin undergoes phase separation into hydrophobic-rich and hydrophilic-rich phases during infiltration of the over-wet demineralized collagen matrix. Such phase separation undermines the integrity and durability of the bond at the composite/tooth interface. This study marks the first time that the polymerization kinetics of model hydrophilic-rich phase of dental adhesive has been determined. Samples were prepared by adding varying water content to neat resins made from 95 and 99wt% hydroxyethylmethacrylate (HEMA) and 5 and 1wt% (2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl1]-propane (BisGMA) prior to light curing. Viscosity of the formulations decreased with increased water content. The photo-polymerization kinetics study was carried out by time-resolved FTIR spectrum collector. All of the samples exhibited two-stage polymerization behavior which has not been reported previously for dental resin formulation. The lowest secondary rate maxima were observed for water content of 10-30%wt. Differential scanning calorimetry (DSC) showed two glass transition temperatures for the hydrophilic-rich phase of dental adhesive. The DSC results indicate that the heterogeneity within the final polymer structure decreased with increased water content. The results suggest a reaction mechanism involving both polymerization-induced phase separation (PIPs) and solvent-induced phase separation (SIPs) for the model hydrophilic-rich phase of dental resin. PMID:24631658

Primer on Durability of Nuclear Power Plant Reinforced Concrete Structures - A Review of Pertinent Factors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naus, Dan J

The objective of this study was to provide a primer on the environmental effects that can affect the durability of nuclear power plant concrete structures. As concrete ages, changes in its properties will occur as a result of continuing microstructural changes (i.e., slow hydration, crystallization of amorphous constituents, and reactions between cement paste and aggregates), as well as environmental influences. These changes do not have to be detrimental to the point that concrete will not be able to meet its performance requirements. Concrete, however, can suffer undesirable changes with time because of improper specifications, a violation of specifications, or adversemore » performance of its cement paste matrix or aggregate constituents under either physical or chemical attack. Contained in this report is a discussion on concrete durability and the relationship between durability and performance, a review of the historical perspective related to concrete and longevity, a description of the basic materials that comprise reinforced concrete, and information on the environmental factors that can affect the performance of nuclear power plant concrete structures. Commentary is provided on the importance of an aging management program.« less

The effect of environmental pH on polymeric transfection efficiency.

PubMed

Kang, Han Chang; Samsonova, Olga; Kang, Sun-Woong; Bae, You Han

2012-02-01

Although polymers, polyplexes, and cells are exposed to various extracellular and intracellular pH environments during polyplex preparation and polymeric transfection, the impact of environmental pH on polymeric transfection has not yet been investigated. This study aims to understand the influence of environmental pH on polymeric transfection by modulating the pH of the transfection medium or the culture medium. Changes in the extracellular pH affected polymeric transfection by way of complex factors such as pH-induced changes in polymer characteristics (e.g., proton buffering capacity and ionization), polyplex characteristics (e.g., size, surface charge, and decomplexation), and cellular characteristics (e.g., cellular uptake, cell cycle phases, and intracellular pH environment). Notably, acidic medium delayed endocytosis, endosomal acidification, cytosolic release, and decomplexation of polyplexes, thereby negatively affecting gene expression. However, acidic medium inhibited mitosis and reduced dilution of gene expression, resulting in increased transfection efficiency. Compared to pH 7.4 medium, acidic transfection medium reduced gene expression 1.6-7.7-fold whereas acidic culture medium enhanced transfection efficiency 2.1-2.6-fold. Polymeric transfection was affected more by the culture medium than by the transfection medium. Understanding the effects of extracellular pH during polymeric transfection may stimulate new strategies for determining effective and safe polymeric gene carriers. Copyright © 2011 Elsevier Ltd. All rights reserved.

High performance dental resin composites with hydrolytically stable monomers.

PubMed

Wang, Xiaohong; Huyang, George; Palagummi, Sri Vikram; Liu, Xiaohui; Skrtic, Drago; Beauchamp, Carlos; Bowen, Rafael; Sun, Jirun

2018-02-01

The objectives of this project were to: 1) develop strong and durable dental resin composites by employing new monomers that are hydrolytically stable, and 2) demonstrate that resin composites based on these monomers perform superiorly to the traditional bisphenol A glycidyl dimethacrylate/triethylene glycol dimethacrylate (Bis-GMA/TEGDMA) composites under testing conditions relevant to clinical applications. New resins comprising hydrolytically stable, ether-based monomer, i.e., triethylene glycol divinylbenzyl ether (TEG-DVBE), and urethane dimethacrylate (UDMA) were produced via composition-controlled photo-polymerization. Their composites contained 67.5wt% of micro and 7.5wt% of nano-sized filler. The performances of both copolymers and composites were evaluated by a battery of clinically-relevant assessments: degree of vinyl conversion (DC: FTIR and NIR spectroscopy); refractive index (n: optical microscopy); elastic modulus (E), flexural strength (F) and fracture toughness (K IC ) (universal mechanical testing); Knoop hardness (HK; indentation); water sorption (W sp ) and solubility (W su ) (gravimetry); polymerization shrinkage (S v ; mercury dilatometry) and polymerization stress (tensometer). The experimental UDMA/TEG-DVBE composites were compared with the Bis-GMA/TEGDMA composites containing the identical filler contents, and with the commercial micro hybrid flowable composite. UDMA/TEG-DBVE composites exhibited n, E, W sp , W su and S v equivalent to the controls. They outperformed the controls with respect to F (up to 26.8% increase), K IC (up to 27.7% increase), modulus recovery upon water sorption (full recovery vs. 91.9% recovery), and stress formation (up to 52.7% reduction). In addition, new composites showed up to 27.7% increase in attainable DC compared to the traditional composites. Bis-GMA/TEGDMA controls exceeded the experimental composites with respect to only one property, the composite hardness. Significantly, up to 18.1% lower HK values in the experimental series (0.458GPa) were still above the clinically required threshold of approx. 0.4GPa. Hydrolytic stability, composition-controlled polymerization and the overall enhancement in clinically-relevant properties of the new resin composites make them viable candidates to replace traditional resin composites as a new generation of strong and durable dental restoratives. Copyright © 2017 The Academy of Dental Materials. All rights reserved.

Evaluation of the durability and antiadhesive action of 2-methacryloyloxyethyl phosphorylcholine grafting on an acrylic resin denture base material.

PubMed

Takahashi, Nana; Iwasa, Fuminori; Inoue, Yuuki; Morisaki, Hirobumi; Ishihara, Kazuhiko; Baba, Kazuyoshi

2014-08-01

The polymer 2-methacryloyloxyethyl phosphorylcholine is currently used on medical devices to prevent infection. Denture plaque-associated infection is regarded as a source of serious dental and medical complications in the elderly population, and denture hygiene, therefore, is an issue of considerable importance for denture wearers. Furthermore, because denture bases are exposed to mechanical stresses, for example, denture brushing, the durability of the coating is important for retaining the antiadhesive function of 2-methacryloyloxyethyl phosphorylcholine. The purpose of this study is to investigate the durability and antiadhesive activity of two 2-methacryloyloxyethyl phosphorylcholine polymer coating techniques: poly-2-methacryloyloxyethyl phosphorylcholine grafting and poly-2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate coating. It was revealed that 2-methacryloyloxyethyl phosphorylcholine polymer coating of the denture base resin polymethyl methacrylate decreases bacterial biofilm formation. Durability was examined by rhodamine staining and elemental surface analysis and by determining the wetting properties of the 2-methacryloyloxyethyl phosphorylcholine polymer-modified polymethyl methacrylate after a friction test that comprised 500 brushing cycles. Antiadhesive activity was examined by using a Streptococcus mutans biofilm formation assay. Poly-2-methacryloyloxyethyl phosphorylcholine-grafted polymethyl methacrylate retained 2-methacryloyloxyethyl phosphorylcholine units and antiadhesive activity even after repetitive mechanical stress, whereas co-n-butyl methacrylate-coated polymethyl methacrylate did not. These results demonstrated that graft polymerization of 2-methacryloyloxyethyl phosphorylcholine on denture surfaces may contribute to the durability of the coating and prevent microbial retention. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Optical Analysis of Transparent Polymeric Material Exposed to Simulated Space Environment

NASA Technical Reports Server (NTRS)

Edwards, David L.; Finckenor, Miria M.

2000-01-01

Many innovations in spacecraft power and propulsion have been recently tested at NASA, particularly in non-chemical propulsion. One improvement in solar array technology is solar concentration using thin polymer film Fresnel lenses. Weight and cost savings were proven with the Solar Concentrator Arrays with Refractive Linear Element Technology (SCARLET)-II array on NASA's Deep Space I spacecraft. The Fresnel lens concentrates solar energy onto high-efficiency solar cells, decreasing the area of solar cells needed for power. Continued efficiency of this power system relies on the thin film's durability in the space environment and maintaining transmission in the 300 - 1000 nm bandwidth. Various polymeric materials have been tested for use in solar concentrators, including Lexan(TM), polyethylene terephthalate (PET), several formulations of Tefzel(Tm) and Teflon(TM), and DC 93-500, the material selected for SCARLET-II. Also tested were several innovative materials including Langley Research Center's CPI and CP2 polymers and atomic oxygen- resistant polymers developed by Triton Systems, Inc. The Environmental Effects Group of the Marshall Space Flight Center's Materials, Processes, and Manufacturing Department exposed these materials to simulated space environment and evaluated them for any change in optical transmission. Samples were exposed to a minimum of 1000 equivalent Sun hours of near-UV radiation (250 - 400 nm wavelength). Materials that appeared robust after near-UV exposure were then exposed to charged particle radiation equivalent to a five-year dose in geosynchronous orbit. These exposures were performed in MSFC's Combined Environmental Effects Test Chamber, a unique facility with the capability to expose materials simultaneously or sequentially to protons, low-energy electrons, high-energy electrons, near UV radiation and vacuum UV radiation. Reflectance measurements can be made on the samples in vacuum. Prolonged exposure to the space environment will decrease the polymer film's transmission and thus reduce the conversion efficiency. A method was developed to normalize the transmission loss and thus rank the materials according to their tolerance to space environmental exposure. Spectral results and the material ranking according to transmission loss are presented.

Sustainability and durability analysis of reinforced concrete structures

NASA Astrophysics Data System (ADS)

Horáková, A.; Broukalová, I.; Kohoutková, A.; Vašková, J.

2017-09-01

The article describes an assessment of reinforced concrete structures in terms of durability and sustainable development. There is a short summary of findings from the literature on evaluation methods for environmental impacts and also about corrosive influences acting on the reinforced concrete structure, about factors influencing the durability of these structures and mathematical models describing the corrosion impacts. Variant design of reinforced concrete structure and assessment of these variants in terms of durability and sustainability was performed. The analysed structure was a concrete ceiling structure of a parking house for cars. The variants differ in strength class of concrete and thickness of concrete slab. It was found that in terms of durability and sustainable development it is significantly preferable to use higher class of concrete. There are significant differences in results of concrete structures durability for different mathematical models of corrosive influences.

Polyimide/Carbon Nanotube Composite Films for Electrostatic Charge Mitigation

NASA Technical Reports Server (NTRS)

Smith, Joseph G., Jr.; Delozier, Donavon M.; Connell, John W.; Watson, Kent A.

2004-01-01

Low color, space environmentally durable polymeric films with sufficient electrical conductivity to mitigate electrostatic charge (ESC) build-up have potential applications on large, deployable, ultra-light weight Gossamer spacecraft as thin film membranes on antennas, solar sails, thermal/optical coatings, multi-layer insulation blankets, etc.. The challenge has been to develop a method to impart robust electrical conductivity into these materials without increasing solar absorptivity (alpha ) or decreasing optical transparency or film flexibility. Since these spacecraft will require significant compaction prior to launch, the film portion of the spacecraft will require folding. The state-of-the-art clear, conductive coating (e.g. indium-tin-oxide, ITO) is brittle and cannot tolerate folding. In this report, doping a polymer with single-walled carbon nanotubes (SWNTs) using two different methods afforded materials with good flexibility and surface conductivities in the range sufficient for ESC mitigation. A coating method afforded materials with minimal effects on the mechanical, optical, and thermo-optical properties as compared to dispersal of SWNTs in the matrix. The chemistry and physical properties of these nanocomposites are discussed.

Environmental Durability of Reinforced Concrete Deck Girders Strengthened for Shear with Surface-Bonded Carbon Fiber-Reinforced Polymer

DOT National Transportation Integrated Search

2009-05-01

"This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effort...

Key Durability Issues with Mullite-Based Environmental Barrier Coatings for Si-Based Ceramics

NASA Technical Reports Server (NTRS)

Lee, Kang N.

1999-01-01

Plasma-sprayed mullite (3Al2O3 central dot 2SiO2) and mullite/yttria-stabilized-zirconia (YSZ) dual layer coatings have been developed to protect silicon-based ceramics from environmental attack. Mullite-based coating systems show excellent durability in air. However, in combustion environments, corrosive species such as molten salt or water vapor penetrate through cracks in the coating and attack the Si-based ceramics along the interface, Thus modification of the coating system for enhanced crack-resistance is necessary for long-term durability in combustion environments. Other key durability issues include interfacial contamination and coating/substrate bonding. Interfacial contamination leads to enhanced oxidation and interfacial pore formation, while weak coating/substrate bonding leads to rapid attack of the interface by corrosive species, both of which can cause premature failure of the coating. Interfacial contamination can be minimized by limiting impurities in coating and substrate materials. The interface may be modified to improve the coating/substrate bond.

Key Durability Issues with Mullite-Based Environmental Barrier Coatings for Si-Based Ceramics

NASA Technical Reports Server (NTRS)

Lee, Kang N.

2000-01-01

Plasma-sprayed mullite (3Al2O3.2SiO2) and mullite/yttria-stabilized-zirconia (YSZ) dual layer coatings have been developed to protect silicon -based ceramics from environmental attack. Mullite-based coating systems show excellent durability in air. However, in combustion environments, corrosive species such as molten salt or water vapor penetrate through cracks in the coating and attack the Si-based ceramics along the interface. Thus the modification of the coating system for enhanced crack-resistance is necessary for long-term durability in combustion environments. Other key durability issues include interfacial contamination and coating/substrate bonding. Interfacial contamination leads to enhanced oxidation and interfacial pore formation, while a weak coating/substrate bonding leads to rapid attack of the interface by corrosive species, both of which can cause a premature failure of the coating. Interfacial contamination can be minimized by limiting impurities in coating and substrate materials. The interface may be modified to improve the coating/substrate bond.

Thin Coatings of Polymeric Carbon and Carbon Nanotubes for Corrosion Protection

DTIC Science & Technology

2009-02-01

Thin Coatings of Polymeric Carbon and Carbon Nanotubes for Corrosion Protection Zafar Iqbal Department of Chemistry and Environmental Science New...Department of Chemistry and Environmental Science ,Newark,NJ,07102 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND

Enhancement of MCF Rubber Utilizing Electric and Magnetic Fields, and Clarification of Electrolytic Polymerization

PubMed Central

Shimada, Kunio

2017-01-01

Many sensors require mechanical durability to resist immense or impulsive pressure and large elasticity, so that they can be installed in or assimilated into the outer layer of artificial skin on robots. Given these demanding requirements, we adopted natural rubber (NR-latex) and developed a new method (NM) for curing NR-latex by the application of a magnetic field under electrolytic polymerization. The aim of the present work is to clarify the new manufacturing process for NR-latex embedded with magnetic compound fluid (MCF) as a conductive filler, and the contribution of the optimization of the new process for sensor. We first clarify the effect of the magnetic field on the enhancement of the NR-latex MCF rubber created by the alignment of magnetic clusters of MCF. Next, SEM, XRD, Raman spectroscopy, and XPS are used for morphological and microscopic observation of the electrolytically polymerized MCF rubber, and a chemical approach measuring pH and ORP of the MCF rubber liquid was used to investigate the process of electrolytic polymerization with a physical mode. We elucidate why the MCF rubber produced by the NM is enhanced with high sensitivity and long-term stability. This process of producing MCF rubber by the NM is closely related to the development of a highly sensitive sensor. PMID:28375182

Applications of polymeric smart materials to environmental problems.

PubMed Central

Gray, H N; Bergbreiter, D E

1997-01-01

New methods for the reduction and remediation of hazardous wastes like carcinogenic organic solvents, toxic materials, and nuclear contamination are vital to environmental health. Procedures for effective waste reduction, detection, and removal are important components of any such methods. Toward this end, polymeric smart materials are finding useful applications. Polymer-bound smart catalysts are useful in waste minimization, catalyst recovery, and catalyst reuse. Polymeric smart coatings have been developed that are capable of both detecting and removing hazardous nuclear contaminants. Such applications of smart materials involving catalysis chemistry, sensor chemistry, and chemistry relevant to decontamination methodology are especially applicable to environmental problems. PMID:9114277

Graphitic Carbon Nitride Supported Catalysts for Polymer Electrolyte Fuel Cells

PubMed Central

2014-01-01

Graphitic carbon nitrides are investigated for developing highly durable Pt electrocatalyst supports for polymer electrolyte fuel cells (PEFCs). Three different graphitic carbon nitride materials were synthesized with the aim to address the effect of crystallinity, porosity, and composition on the catalyst support properties: polymeric carbon nitride (gCNM), poly(triazine) imide carbon nitride (PTI/Li+Cl–), and boron-doped graphitic carbon nitride (B-gCNM). Following accelerated corrosion testing, all graphitic carbon nitride materials are found to be more electrochemically stable compared to conventional carbon black (Vulcan XC-72R) with B-gCNM support showing the best stability. For the supported catalysts, Pt/PTI-Li+Cl– catalyst exhibits better durability with only 19% electrochemical surface area (ECSA) loss versus 36% for Pt/Vulcan after 2000 scans. Superior methanol oxidation activity is observed for all graphitic carbon nitride supported Pt catalysts on the basis of the catalyst ECSA. PMID:24748912

High Performance Variable Emittance Devices for Spacecraft Application Based on Conducting Polymers Coupled with Ionic Liquids

NASA Astrophysics Data System (ADS)

Chandrasekhar, Prasanna; Zay, Brian J.; Barbolt, Scott; Werner, Robert; Birur, Gajanana C.; Paris, Anthony

2009-03-01

This contribution describes the fabrication, function and performance of thin-film variable emittance electrochromic skins fabricated using poly(aniline) as the conducting polymer (CP), a long-chain polymeric dopant, and an ionic liquid as electrolyte. The ionic electrolyte allows operation in space vacuum without any seals. A unique, space-durable coating applied to the external surface of the skins drastically lowers the solar absorptance of the skins, such that in their dark (highly emissive) electrochromic state, it is no more than 0.44, whilst in their light electrochromic state, it is ca. 0.3. Data presented show tailorable, variations from 0.19 to 0.90, ∀(s)<0.3, and nearly indefinite cyclability. Extended thermal vacuum, atomic-O, micrometeoroid, VUV and other studies show excellent space durability. Performance of a doughnut-shaped skin designed for a specific micro-spacecraft is also described.

40 CFR 86.1822-01 - Durability data vehicle selection.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 19 2010-07-01 2010-07-01 false Durability data vehicle selection. 86.1822-01 Section 86.1822-01 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... engineering judgment in making this selection. (b) The manufacturer may select, using good engineering...

Enhancing durability of wood-based composites with nanotechnology

Treesearch

Carol Clausen

2012-01-01

Wood protection systems are needed for engineered composite products that are susceptible to moisture and biodeterioration. Protection systems using nano-materials are being developed to enhance the durability of wood-based composites through improved resistance to biodeterioration, reduced environmental impact from chemical leaching, and improved resistance to...

Environmental durability of reinforced concrete deck girders strengthened for shear with surface-bonded carbon fiber-reinforced polymer : final report.

DOT National Transportation Integrated Search

2009-05-01

This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effort ...

Environmental durability of reinforced concrete deck girders strengthened for shear with surface bonded carbon fiber-reinforced polymer : final report.

DOT National Transportation Integrated Search

2009-05-01

This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced : concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effor...

Thermomechanical and Environmental Durability of Environmental Barrier Coated Ceramic Matrix Composites Under Thermal Gradients

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Bhatt, Ramakrishna T.; Harder, Bryan

2016-01-01

This paper presents the developments of thermo-mechanical testing approaches and durability performance of environmental barrier coatings (EBCs) and EBC coated SiCSiC ceramic matrix composites (CMCs). Critical testing aspects of the CMCs will be described, including state of the art instrumentations such as temperature, thermal gradient, and full field strain measurements; materials thermal conductivity evolutions and thermal stress resistance; NDE methods; thermo-mechanical stress and environment interactions associated damage accumulations. Examples are also given for testing ceramic matrix composite sub-elements and small airfoils to help better understand the critical and complex CMC and EBC properties in engine relevant testing environments.

40 CFR 1045.245 - How do I determine deterioration factors from exhaust durability testing?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 34 2013-07-01 2013-07-01 false How do I determine deterioration factors from exhaust durability testing? 1045.245 Section 1045.245 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION...

40 CFR 1045.245 - How do I determine deterioration factors from exhaust durability testing?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 33 2011-07-01 2011-07-01 false How do I determine deterioration factors from exhaust durability testing? 1045.245 Section 1045.245 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION...

40 CFR 1045.245 - How do I determine deterioration factors from exhaust durability testing?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false How do I determine deterioration factors from exhaust durability testing? 1045.245 Section 1045.245 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION...

40 CFR 1045.245 - How do I determine deterioration factors from exhaust durability testing?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 34 2012-07-01 2012-07-01 false How do I determine deterioration factors from exhaust durability testing? 1045.245 Section 1045.245 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION...

40 CFR 1045.245 - How do I determine deterioration factors from exhaust durability testing?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 33 2014-07-01 2014-07-01 false How do I determine deterioration factors from exhaust durability testing? 1045.245 Section 1045.245 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION...

Evaluation of the color stability of two techniques for reproducing artificial irides after microwave polymerization

PubMed Central

GOIATO, Marcelo Coelho; dos SANTOS, Daniela Micheline; MORENO, Amália; GENNARI-FILHO, Humberto; PELLIZZER, Eduardo Piza

2011-01-01

The use of ocular prostheses for ophthalmic patients aims to rebuild facial aesthetics and provide an artificial substitute to the visual organ. Natural intemperate conditions promote discoloration of artificial irides and many studies have attempted to produce irides with greater chromatic paint durability using different paint materials. Objectives The present study evaluated the color stability of artificial irides obtained with two techniques (oil painting and digital image) and submitted to microwave polymerization. Material and Methods Forty samples were fabricated simulating ocular prostheses. Each sample was constituted by one disc of acrylic resin N1 and one disc of colorless acrylic resin with the iris interposed between the discs. The irides in brown and blue color were obtained by oil painting or digital image. The color stability was determined by a reflection spectrophotometer and measurements were taken before and after microwave polymerization. Statistical analysis of the techniques for reproducing artificial irides was performed by applying the normal data distribution test followed by 2-way ANOVA and Tukey HSD test (α=.05). Results Chromatic alterations occurred in all specimens and statistically significant differences were observed between the oil-painted samples and those obtained by digital imaging. There was no statistical difference between the brown and blue colors. Independently of technique, all samples suffered color alterations after microwave polymerization. Conclusion The digital imaging technique for reproducing irides presented better color stability after microwave polymerization. PMID:21625733

Preparation of a polymeric ionic liquid-coated solid-phase microextraction fiber by surface radical chain-transfer polymerization with stainless steel wire as support.

PubMed

Feng, Juanjuan; Sun, Min; Xu, Lili; Li, Jubai; Liu, Xia; Jiang, Shengxiang

2011-10-28

Polymeric 1-vinyl-3-octylimidazolium hexafluorophosphate was synthesized in situ on stainless steel wire by surface radical chain-transfer polymerization and used as sensitive coatings in solid-phase microextraction. The outer surface of the stainless steel wire was firstly coated with microstructured silver layer via silver mirror reaction and then functionalized with self-assembled monolayers of 1,8-octanedithiol, which acted as chain transfer agent in the polymerization. Coupled to gas chromatography, extraction performance of the fiber was studied with both headspace and direct-immersion modes using benzene, toluene, ethylbenzene and xylenes (BTEX), phenols and polycyclic aromatic hydrocarbon (PAHs) as model analytes. In combination with the microstructured silver layer, the PIL-coated fiber exhibited high extraction efficiency. Linear ranges for BTEX with headspace mode were in the range of 0.2-1000 μg L(-1) for benzene, and 0.1-1000 μg L(-1) for toluene, ethylbenzene and xylenes. Limits of detection (LODs) were from 0.02 to 0.05 μg L(-1). Wide linear ranges of direct-immersion mode for the extraction of several phenols and PAHs were also obtained with correlation coefficients (R) from 0.9943 to 0.9997. The proposed fiber showed good durability with long lifetime. RSDs of 56 times extraction were still in an acceptable range, from 8.85 to 22.8%. Copyright © 2011 Elsevier B.V. All rights reserved.

Creation of biological module for self-regulating ecological system by the way of polymerization of composite materials in free space.

PubMed

Kondyurin, A; Lauke, B; Kondyurina, I; Orba, E

2004-01-01

The large-size frame of space ship and space station can be created with the use of the technology of the polymerization of fiber-filled composites and a liquid reactionable matrix applied in free space or on the other space body when the space ship or space station will be used during a long period of time. For the polymerization of the station frame the fabric impregnated with a long-life polymer matrix (prepreg) is prepared in terrestrial conditions and, after folding, can be shipped in a compact container to orbit and kept folded on board the station. In due time the prepreg is carried out into free space and unfolded. Then a reaction of matrix polymerization starts. After reaction of polymerization the durable frame is ready for exploitation. After that, the frame can be filled out with air, the apparatus and life support systems. The technology can be used for creation of biological frame as element of self regulating ecological system, and for creation of technological frame which can be used for a production of new materials on Earth orbit in microgravity conditions and on other space bodies (Mars, Moon, asteroids) for unique high price mineral extraction. Based on such technology a future space base on Earth orbit with volume of 10(6) m3 and a crew of 100 astronauts is considered. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

Durability of a novel durable bait for control of subterranean termites (Isoptera: Rhinotermitidae): results of five-year field aging studies.

PubMed

Eger, J E; Hamm, R L; Demark, J J; Chin-Heady, E; Tolley, M P; Benson, E P; Zungoli, P A; Smith, M S; Spomer, N A

2014-06-01

A durable termite bait containing 0.5% noviflumuron was evaluated for physical durability, retention of active ingredient, consumption by termites, and toxicity to termites over 5 yr in field studies at locations in Indiana, Mississippi, and South Carolina. Plots in Indiana and Mississippi included both natural rainfall and irrigated plots, while plots in South Carolina received only natural rainfall. Samples collected every 3 mo for the first 4 yr were evaluated for consumption with a 7 d no-choice bioassay using Reticulitermes flavipes (Kollar). Consumption and toxicity of 5 yr samples were evaluated in similar bioassays conducted for 42 d. Durable baits received from field sites had some cracking, and a small amount of external flaking, but no major deterioration based on visual observation. There were no significant differences in noviflumuron concentration over the 5-yr period and no trend toward reduced concentrations of noviflumuron over time. Consumption of aged durable baits over 4 yr was variable, but termites usually consumed more aged durable bait than fresh durable bait and the differences were frequently significant. There were some exceptions, but termites consumed significantly more fresh durable bait than aged durable bait in only 4% of observations. When 5 yr samples were evaluated, consumption was lowest for fresh durable bait and termites consumed significantly more aged durable bait from irrigated plots in Indiana and from both natural and irrigated plots in Mississippi than fresh durable bait. Survival of termites fed blank durable bait was significantly higher than that for termites fed any of the baits containing noviflumuron and there were no significant differences in survival among the noviflumuron durable baits. Our results suggest that the bait would be durable for at least 5 yr and possibly longer under most environmental conditions.

In Vitro Evaluation of a Novel Hemodynamically Optimized Trileaflet Polymeric Prosthetic Heart Valve

PubMed Central

Claiborne, Thomas E.; Sheriff, Jawaad; Kuetting, Maximilian; Steinseifer, Ulrich; Slepian, Marvin J.; Bluestein, Danny

2013-01-01

Calcific aortic valve disease is the most common and life threatening form of valvular heart disease, characterized by stenosis and regurgitation, which is currently treated at the symptomatic end-stages via open-heart surgical replacement of the diseased valve with, typically, either a xenograft tissue valve or a pyrolytic carbon mechanical heart valve. These options offer the clinician a choice between structural valve deterioration and chronic anticoagulant therapy, respectively, effectively replacing one disease with another. Polymeric prosthetic heart valves (PHV) offer the promise of reducing or eliminating these complications, and they may be better suited for the new transcatheter aortic valve replacement (TAVR) procedure, which currently utilizes tissue valves. New evidence indicates that the latter may incur damage during implantation. Polymer PHVs may also be incorporated into pulsatile circulatory support devices such as total artificial heart and ventricular assist devices that currently employ mechanical PHVs. Development of polymer PHVs, however, has been slow due to the lack of sufficiently durable and biocompatible polymers. We have designed a new trileaflet polymer PHV for surgical implantation employing a novel polymer—xSIBS—that offers superior bio-stability and durability. The design of this polymer PHV was optimized for reduced stresses, improved hemodynamic performance, and reduced thrombogenicity using our device thrombogenicity emulation (DTE) methodology, the results of which have been published separately. Here we present our new design, prototype fabrication methods, hydrodynamics performance testing, and platelet activation measurements performed in the optimized valve prototype and compare it to the performance of a gold standard tissue valve. The hydrodynamic performance of the two valves was comparable in all measures, with a certain advantage to our valve during regurgitation. There was no significant difference between the platelet activation rates of our polymer valve and the tissue valve, indicating that similar to the latter, its recipients may not require anticoagulation. This work proves the feasibility of our optimized polymer PHV design and brings polymeric valves closer to clinical viability. PMID:23445066

Durability of Polymeric Encapsulation Materials for a PMMA/glass Concentrator Photovoltaic System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, David C.; Kempe, Michael D.; Muller, Matthew T

2014-04-08

The durability of polymeric encapsulation materials was examined using outdoor exposure at the nominal geometric concentration of 500 suns. The results for 36 months cumulative field deployment are presented for materials including: poly(ethylene-co-vinyl acetate), (EVA); polyvinyl butyral (PVB); ionomer; polyethylene/ polyoctene copolymer (PO); thermoplastic polyurethane (TPU); poly(dimethylsiloxane) (PDMS); poly(diphenyl dimethyl siloxane) (PDPDMS); and poly(phenyl-methyl siloxane) (PPMS). Measurements of the field conditions including ambient temperature and ultraviolet (UV) dose were recorded at the test site during the experiment. Measurements for the experiment included optical transmittance (with subsequent analysis of solar-weighted transmittance, UV cut-off wavelength, and yellowness index), mass, visual photography, photoelasticmore » imaging, and fluorescence spectroscopy. While the results to date for EVA are presented and discussed, examination here focuses more on the siloxane materials. A specimen recently observed to fail by thermal decomposition is discussed in terms of the implementation of the experiment as well as its fluorescence signature, which was observed to become more pronounced with age. Modulated thermogravimetry (allowing determination of the activation energy of thermal decomposition) was performed on a subset of the siloxanes to quantify the propensity for decomposition at elevated temperatures. Supplemental, Pt-catalyst- and primer-solutions as well as peroxide-cured PDMS specimens were examined to assess the source of the luminescence. The results of the study including the change in optical transmittance, observed failure modes, and subsequent analyses of the failure modes are described in the conclusions.« less

Synthesis of a fluorine-free polymeric water-repellent agent for creation of superhydrophobic fabrics

NASA Astrophysics Data System (ADS)

Shen, Keke; Yu, Miao; Li, Qianqian; Sun, Wei; Zhang, Xiting; Quan, Miao; Liu, Zhengtang; Shi, Suqing; Gong, Yongkuan

2017-12-01

A non-fluorinated polymeric alkylsilane, poly(isobutyl methacrylate-co-3-methacryloxypropyltrimethoxysilane) (PIT), is designed and synthesized to replace the commercial long-chain perfluoroalkylsilane (FAS) water-repellent agent. The superhydrophobic polyester fabrics are prepared by anchoring sol-gel derived silica nanoparticles onto alkali-treated polyester fabric surfaces and subsequently hydrophobilizing with PIT, using FAS as control. The surface chemical composition, surface morphology, wetting behavior and durability of the modified polyester fabrics are characterized by scanning electron microscopy (SEM), X-ray photoelectron spectrophotometer (XPS) and video-based contact angle goniometer, respectively. The results show that a porous silica layer could be successfully fabricated onto the surface of polyester fabric through base-catalyzed sol-gel process with tetraethoxysilane (TEOS) as precursor, incorporating additional nanostructured roughness essential for superhydrophobicity. At the same time, such a silica primer layer could provide both secondary reactive moieties (-Si - OH) for the subsequent surface hydrophobization and acceptable adhesion at the silica-polyester fabric interface. When silica modified polyester fabric (SiO2@ fabric) is hydrophobized by PIT solution (10 mg/mL), excellent water-repellency could be obtained. The water contact angle is up to 154° and the sliding angle is about 5°. Compared with small molecule water-repellent agent FAS, PIT modified SiO2@ fabric exhibits greatly improved solvent resistance under ultra-sonication, abrasion and simulated laundering durability. The anti-stain property of PIT-modified SiO2@ fabric is also evaluated by using different aqueous colored solutions.

Durability of polymeric encapsulation materials in a PMMA/glass concentrator photovoltaic system

DOE PAGES

Miller, David C.; Kempe, Michael D.; Muller, Matthew T.; ...

2016-07-13

We examined the durability of polymeric encapsulation materials using outdoor exposure at the nominal geometric concentration of 500 suns. The results for 36-month cumulative field deployment are presented for materials including: poly(ethylene-co-vinyl acetate), (EVA); polyvinyl butyral (PVB); ionomer; polyethylene/polyoctene copolymer (PO); thermoplastic polyurethane (TPU); poly(dimethylsiloxane) (PDMS); poly(diphenyl dimethyl siloxane) (PDPDMS); and poly(phenyl-methyl siloxane) (PPMS). Measurements of the field conditions including ambient temperature and ultraviolet (UV) dose were recorded at the test site during the experiment. Our measurements for the experiment included optical transmittance (with subsequent analysis of solar-weighted transmittance, UV cut-off wavelength, and yellowness index), mass, visual photography, photoelastic imaging,more » and fluorescence spectroscopy. While the results to date for EVA are presented and discussed, examination here focuses more on the siloxane materials. A specimen recently observed to fail by thermal decomposition is discussed in terms of the implementation of the experiment as well as its fluorescence signature, which was observed to become more pronounced with age. Modulated thermogravimetry (allowing determination of the activation energy of thermal decomposition) was performed on a subset of the siloxanes to quantify the propensity for decomposition at elevated temperatures. Supplemental, Pt-catalyst- and primer-solutions as well as peroxide-cured PDMS specimens were examined to assess the source of the luminescence. Furthermore, our results, including the change in optical transmittance, observed failure modes, and subsequent analyses of the failure modes are described in the conclusions.« less

Durability Issues for the Protection of Materials from Atomic Oxygen Attack in Low Earth Orbit

NASA Astrophysics Data System (ADS)

Banks, B. A.; Lenczewski, M.; Demko, R.

2002-01-01

Low Earth orbital atomic oxygen is capable of eroding most polymeric materials typically used on spacecraft. Solar array blankets, thermal control polymers, and carbon fiber matrix composites are readily oxidized to become thinner and less capable of supporting the loads imposed upon them. Protective coatings have been developed that are or become durable to atomic oxygen to prevent oxidative erosion of the underlying polymers. However, the details of the chemistry, surface roughness and coating configuration can play a significant role as to whether or not the coating provides long duration atomic oxygen protection. Identical coatings on different surface roughness surfaces can produce drastically have drastically different durability results. Poor choice of protective coatings or self-protecting materials can also result in contamination of surrounding spacecraft surfaces. Such contamination can deposit on optical or thermal control surfaces resulting in changes in solar absorbtance, transmittance and reflectance of surfaces. Examples of successful and unsuccessful techniques used for atomic oxygen durability or protection will be presented based on actual results from low Earth orbital spacecraft. Investigations of the causes of undesired consequences or protective coating failures will be presented including ground laboratory experimental analysis as well as computational modeling. Atomic oxygen protective coating results from various low Earth orbital missions including the Long Duration Exposure Facility, the European Retrievable Carrier, Mir, and International Space Station will be presented to illustrate examples of protection successes as well as failures including analyses of the causes for the differences and proposed solutions.

Urbanization, regime type and durability, and environmental degradation in Ghana.

PubMed

Adams, Samuel; Adom, Philip Kofi; Klobodu, Edem Kwame Mensah

2016-12-01

This study examines the effect of urbanization, income, trade openness, and institutional quality (i.e., regime type and durability) on environmental degradation in Ghana over the period 1965-2011. Using the bounds test approach to cointegration and the Fully Modified Phillip-Hansen (FMPH) technique, the findings show that urbanization, income, trade openness, and institutional quality have long-run cointegration with environmental degradation. Further, the results show that income, trade openness, and institutional quality are negatively associated with environmental degradation. This suggests that income, trade openness, and institutional quality enhance environmental performance. Urbanization, however, is positively related to environmental degradation. Additionally, long-run estimates conditioned on institutional quality reveal that the extent to which trade openness and urbanization enhance environmental performance is largely due to the presence of quality institutions (or democratic institutions). Finally, controlling for structural breaks, we find that trade openness, urbanization, and regime type (i.e., democracy) improve environmental performance significantly after the 1970s except for income.

40 CFR 86.1825-01 - Durability demonstration procedures for refueling emissions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 19 2010-07-01 2010-07-01 false Durability demonstration procedures for refueling emissions. 86.1825-01 Section 86.1825-01 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES (CONTINUED) General Compliance...

40 CFR 86.1825-08 - Durability demonstration procedures for refueling emissions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 19 2010-07-01 2010-07-01 false Durability demonstration procedures for refueling emissions. 86.1825-08 Section 86.1825-08 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES (CONTINUED) General Compliance...

Electrospun composite nanofiber fabrics containing uniformly dispersed antimicrobial agents as an innovative type of polymeric materials with superior antimicrobial efficacy.

PubMed

Sun, Xinbo; Zhang, Lifeng; Cao, Zhengbing; Deng, Ying; Liu, Li; Fong, Hao; Sun, Yuyu

2010-04-01

Herein we report that electrospun composite nanofiber fabrics containing uniformly dispersed antimicrobial agents and having large surface-to-mass ratios are an innovative type of antimicrobial polymeric materials with durable, nonleachable, and biocompatible characteristics, and more importantly, superior antimicrobial efficacy. Specifically, electrospun cellulose acetate (CA) nanofiber fabrics containing an N-halamine antimicrobial agent of bis(N-chloro-2,2,6,6-tetramethyl-4-piperidinyl) sebacate (Cl-BTMP) were prepared and evaluated; the results of antimicrobial efficacy indicated that the electrospun composite nanofiber fabrics substantially outperformed the control samples that were solution-cast films containing identical amounts of CA and Cl-BTMP. Additionally, the results of trypan blue assay test suggested that the electrospun composite nanofiber fabrics also had excellent mammal cell viability. The developed electrospun composite nanofiber fabrics with superior antimicrobial efficacy are expected to find vital applications in biomedical, hygienic, and many other fields.

Mechanical properties on geopolymer brick: A review

NASA Astrophysics Data System (ADS)

Deraman, L. M.; Abdullah, M. M. A.; Ming, L. Y.; Ibrahim, W. M. W.; Tahir, M. F. M.

2017-09-01

Bricks has stand for many years as durable construction substantial, especially in the area of civil engineering to construct buildings. Brick commonly used in the structure of buildings as a construction wall, cladding, facing perimeter, paving, garden wall and flooring. The contribution of ordinary Portland cement (OPC) in cement bricks production worldwide to greenhouse gas emissions. Due to this issue, some researchers have done their study with other materials to produce bricks, especially as a by-product material. Researchers take effort in this regard to synthesizing from by-product materials such as fly ash, bottom ash and kaolin that are rich in silicon and aluminium in the development of inorganic alumina-silicate polymer, called geopolymer Geopolymer is a polymerization reaction between various aluminosilicate oxides with silicates solution or alkali hydroxide solution forming polymerized Si-O-Al-O bonds. This paper summarized some research finding of mechanical properties of geopolymer brick using by-product materials.

Biomimetic polymeric superhydrophobic surfaces and nanostructures: from fabrication to applications.

PubMed

Wen, Gang; Guo, ZhiGuang; Liu, Weimin

2017-03-09

Numerous research studies have contributed to the development of mature superhydrophobic systems. The fabrication and applications of polymeric superhydrophobic surfaces have been discussed and these have attracted tremendous attention over the past few years due to their excellent properties. In general, roughness and chemical composition, the two most crucial factors with respect to surface wetting, provide the basic criteria for yielding polymeric superhydrophobic materials. Furthermore, with their unique properties and flexible configurations, polymers have been one of the most efficient materials for fabricating superhydrophobic materials. This review aims to summarize the most recent progress in polymeric superhydrophobic surfaces. Significantly, the fundamental theories for designing these materials will be presented, and the original methods will be introduced, followed by a summary of multifunctional superhydrophobic polymers and their applications. The principles of these methods can be divided into two categories: the first involves adding nanoparticles to a low surface energy polymer, and the other involves combining a low surface energy material with a textured surface, followed by chemical modification. Notably, surface-initiated radical polymerization is a versatile method for a variety of vinyl monomers, resulting in controlled molecular weights and low polydispersities. The surfaces produced by these methods not only possess superhydrophobicity but also have many applications, such as self-cleaning, self-healing, anti-icing, anti-bioadhesion, oil-water separation, and even superamphiphobic surfaces. Interestingly, the combination of responsive materials and roughness enhances the responsiveness, which allows the achievement of intelligent transformation between superhydrophobicity and superhydrophilicity. Nevertheless, surfaces with poor physical and chemical properties are generally unable to withstand the severe conditions of the outside world; thus, it is necessary to optimize the performances of such materials to yield durable superhydrophobic surfaces. To sum up, some challenges and perspectives regarding the future research and development of polymeric superhydrophobic surfaces are presented.

Advanced Environmental Barrier Coatings Development for Si-Based Ceramics

NASA Technical Reports Server (NTRS)

Zhu, Dong-Ming; Choi, R. Sung; Robinson, Raymond C.; Lee, Kang N.; Bhatt, Ramakrishna T.; Miller, Robert A.

2005-01-01

Advanced environmental barrier coating concepts based on multi-component HfO2 (ZrO2) and modified mullite systems are developed for monolithic Si3N4 and SiC/SiC ceramic matrix composite (CMC) applications. Comprehensive testing approaches were established using the water vapor cyclic furnace, high pressure burner rig and laser heat flux steam rig to evaluate the coating water vapor stability, cyclic durability, radiation and erosion resistance under simulated engine environments. Test results demonstrated the feasibility and durability of the environmental barrier coating systems for 2700 to 3000 F monolithic Si3N4 and SiC/SiC CMC component applications. The high-temperature-capable environmental barrier coating systems are being further developed and optimized in collaboration with engine companies for advanced turbine engine applications.

Multiple stimulus reversible hydrogels

DOEpatents

Gutowska, Anna; Krzyminski, Karol J.

2003-12-09

A polymeric solution capable of gelling upon exposure to a critical minimum value of a plurality of environmental stimuli is disclosed. The polymeric solution may be an aqueous solution utilized in vivo and capable of having the gelation reversed if at least one of the stimuli fall below, or outside the range of, the critical minimum value. The aqueous polymeric solution can be used either in industrial or pharmaceutical environments. In the medical environment, the aqueous polymeric solution is provided with either a chemical or radioisotopic therapeutic agent for delivery to a specific body part. The primary advantage of the process is that exposure to one environmental stimuli alone will not cause gelation, thereby enabling the therapeutic agent to be conducted through the body for relatively long distances without gelation occurring.

Multiple stimulus reversible hydrogels

DOEpatents

Gutowska, Anna; Krzyminski, Karol J.

2006-04-25

A polymeric solution capable of gelling upon exposure to a critical minimum value of a plurality of environmental stimuli is disclosed. The polymeric solution may be an aqueous solution utilized in vivo and capable of having the gelation reversed if at least one of the stimuli fall below, or outside the range of, the critical minimum value. The aqueous polymeric solution can be used either in industrial or pharmaceutical environments. In the medical environment, the aqueous polymeric solution is provided with either a chemical or radioisotopic therapeutic agent for delivery to a specific body part. The primary advantage of the process is that exposure to one environmental stimuli alone will not cause gelation, thereby enabling the therapeutic agent to be conducted through the body for relatively long distances without gelation occurring.

Radical-Mediated Enzymatic Polymerizations

PubMed Central

Zavada, Scott R.; Battsengel, Tsatsral; Scott, Timothy F.

2016-01-01

Polymerization reactions are commonly effected by exposing monomer formulations to some initiation stimulus such as elevated temperature, light, or a chemical reactant. Increasingly, these polymerization reactions are mediated by enzymes―catalytic proteins―owing to their reaction efficiency under mild conditions as well as their environmental friendliness. The utilization of enzymes, particularly oxidases and peroxidases, for generating radicals via reduction-oxidation mechanisms is especially common for initiating radical-mediated polymerization reactions, including vinyl chain-growth polymerization, atom transfer radical polymerization, thiol–ene step-growth polymerization, and polymerization via oxidative coupling. While enzyme-mediated polymerization is useful for the production of materials intended for subsequent use, it is especially well-suited for in situ polymerizations, where the polymer is formed in the place where it will be utilized. Such polymerizations are especially useful for biomedical adhesives and for sensing applications. PMID:26848652

Development of Advanced Environmental Barrier Coatings for SiC/SiC Ceramic Matrix Composites: Path Toward 2700 F Temperature Capability and Beyond

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Hurst, Janet B.; Good, Brian; Costa, Gustavo; Bhatt, Ramakrishna T.; Fox, Dennis S.

2017-01-01

Advanced environmental barrier coating systems for SiC-SiC Ceramic Matrix Composite (CMC) turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant coating development challenges is to achieve prime-reliant environmental barrier coating systems to meet the future 2700F EBC-CMC temperature stability and environmental durability requirements. This presentation will emphasize recent NASA environmental barrier coating system testing and down-selects, particularly the development path and properties towards 2700-3000F durability goals by using NASA hafnium-hafnia-rare earth-silicon-silicate composition EBC systems for the SiC-SiC CMC turbine component applications. Advanced hafnium-based compositions for enabling next generation EBC and CMCs capabilities towards ultra-high temperature ceramic coating systems will also be briefly mentioned.

Preparation of sulfonated graphene/polypyrrole solid-phase microextraction coating by in situ electrochemical polymerization for analysis of trace terpenes.

PubMed

Zhang, Chengjiang; Zhang, Zhuomin; Li, Gongke

2014-06-13

In this study, a novel sulfonated graphene/polypyrrole (SG/PPy) solid-phase microextraction (SPME) coating was prepared and fabricated on a stainless-steel wire by a one-step in situ electrochemical polymerization method. Crucial preparation conditions were optimized as polymerization time of 15min and SG doping amount of 1.5mg/mL. SG/PPy coating showed excellent thermal stability and mechanical durability with a long lifespan of more than 200 stable replicate extractions. SG/PPy coating demonstrated higher extraction selectivity and capacity to volatile terpenes than commonly-used commercial coatings. Finally, SG/PPy coating was practically applied for the analysis of volatile components from star anise and fennel samples. The majority of volatile components identified were terpenes, which suggested the ultra-high extraction selectivity of SG/PPy coating to terpenes during real analytical projects. Four typical volatile terpenes were further quantified to be 0.2-27.4μg/g from star anise samples with good recoveries of 76.4-97.8% and 0.1-1.6μg/g from fennel samples with good recoveries of 80.0-93.1%, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

Durability Challenges for Next Generation of Gas Turbine Engine Materials

NASA Technical Reports Server (NTRS)

Misra, Ajay K.

2012-01-01

Aggressive fuel burn and carbon dioxide emission reduction goals for future gas turbine engines will require higher overall pressure ratio, and a significant increase in turbine inlet temperature. These goals can be achieved by increasing temperature capability of turbine engine hot section materials and decreasing weight of fan section of the engine. NASA is currently developing several advanced hot section materials for increasing temperature capability of future gas turbine engines. The materials of interest include ceramic matrix composites with 1482 - 1648 C temperature capability, advanced disk alloys with 815 C capability, and low conductivity thermal barrier coatings with erosion resistance. The presentation will provide an overview of durability challenges with emphasis on the environmental factors affecting durability for the next generation of gas turbine engine materials. The environmental factors include gaseous atmosphere in gas turbine engines, molten salt and glass deposits from airborne contaminants, impact from foreign object damage, and erosion from ingestion of small particles.

A Protocol for Measuring Pull-off Stress of Wound-Treatment Polymers

PubMed Central

Kheyfets, Vitaly O.; Thornton, Rita C.; Kowal, Mikala; Finol, Ender A.

2014-01-01

Skin wounds and burns compromise the body's natural barrier to bacteria and other pathogens. While many forms of wound dressings are available, polymeric films are advantageous for various reasons, ranging from the ease of application to durability. One common drawback of using polymeric films for a wound bandage is that the films tend to adhere to common inanimate objects. Patients spend hours in contact with soft and hard materials pressed against their skin, which, if the skin was dressed with a polymeric film, would inflict further wound damage upon body movement. In this work, we present a novel technique that allowed for measuring polymeric tackiness, after a long incubation period, with materials regularly encountered in a hospital or home setting, and soft fabrics. The polymers were exposed to an environment intended to simulate daily conditions and the technique is designed to perform multiple experiments simultaneously with ease. Four commercially available polymers (new-skin, no-sting skin-prep, skin shield, and Silesse) were tested as proof-of-concept to gather preliminary data for an overall assessment of wound treatment efficacy, resulting in the estimation of pull-off stress of the polymers from a specimen of porcine skin. Silesse did not reveal a measurable tackiness, no-sting skin-prep had the highest mean tackiness (13.8 kPa), while the mean tackiness between new-skin and skin shield was approximately equal (9.8 kPa vs. 10.1 kPa, respectively), p = 0.05. Future work on polymeric fluids for wound dressing applications should include tensile stress and dynamic viscosity estimations. PMID:24718322

Simultaneous acoustic and dielectric real time curing monitoring of epoxy systems

NASA Astrophysics Data System (ADS)

Gkikas, G.; Saganas, Ch.; Grammatikos, S. A.; Aggelis, D. G.; Paipetis, A. S.

2012-04-01

The attainment of structural integrity of the reinforcing matrix in composite materials is of primary importance for the final properties of the composite structure. The detailed monitoring of the curing process on the other hand is paramount (i) in defining the optimal conditions for the impregnation of the reinforcement by the matrix (ii) in limiting the effects of the exotherm produced by the polymerization reaction which create unwanted thermal stresses and (iii) in securing optimal behavior in matrix controlled properties, such as off axis or shear properties and in general the durability of the composite. Dielectric curing monitoring is a well known technique for distinguishing between the different stages of the polymerization of a typical epoxy system. The technique successfully predicts the gelation and the vitrification of the epoxy and has been extended for the monitoring of prepregs. Recent work has shown that distinct changes in the properties of the propagated sound in the epoxy which undergoes polymerization is as well directly related to the gelation and vitrification of the resin, as well as to the attainment of the final properties of the resin system. In this work, a typical epoxy is simultaneously monitored using acoustic and dielectric methods. The system is isothermally cured in an oven to avoid effects from the polymerization exotherm. Typical broadband sensors are employed for the acoustic monitoring, while flat interdigital sensors are employed for the dielectric scans. All stages of the polymerization process were successfully monitored and the validity of both methods was cross checked and verified.

Electrical condition monitoring method for polymers

DOEpatents

Watkins, Jr. Kenneth S.; Morris, Shelby J.; Masakowski, Daniel D.; Wong, Ching Ping; Luo, Shijian

2010-02-16

An electrical condition monitoring method utilizes measurement of electrical resistivity of a conductive composite degradation sensor to monitor environmentally induced degradation of a polymeric product such as insulated wire and cable. The degradation sensor comprises a polymeric matrix and conductive filler. The polymeric matrix may be a polymer used in the product, or it may be a polymer with degradation properties similar to that of a polymer used in the product. The method comprises a means for communicating the resistivity to a measuring instrument and a means to correlate resistivity of the degradation sensor with environmentally induced degradation of the product.

Transcatheter Pulmonary Valve Replacement by Hybrid Approach Using a Novel Polymeric Prosthetic Heart Valve: Proof of Concept in Sheep

PubMed Central

Xu, Tong-yi; Zhang, Zhi-gang; Li, Xin; Han, Lin; Xu, Zhi-yun

2014-01-01

Background Since 2000, transcatheter pulmonary valve replacement has steadily advanced. However, the available prosthetic valves are restricted to bioprosthesis which have defects like poor durability. Polymeric heart valve is thought as a promising alternative to bioprosthesis. In this study, we introduced a novel polymeric transcatheter pulmonary valve and evaluated its feasibility and safety in sheep by a hybrid approach. Methods We designed a novel polymeric trileaflet transcatheter pulmonary valve with a balloon-expandable stent, and the valve leaflets were made of 0.1-mm expanded polytetrafluoroethylene (ePTFE) coated with phosphorylcholine. We chose glutaraldehyde-treated bovine pericardium valves as control. Pulmonary valve stents were implanted in situ by a hybrid transapical approach in 10 healthy sheep (8 for polymeric valve and 2 for bovine pericardium valve), weighing an average of 22.5±2.0 kg. Angiography and cardiac catheter examination were performed after implantation to assess immediate valvular functionality. After 4-week follow-up, angiography, echocardiography, computed tomography, and cardiac catheter examination were used to assess early valvular function. One randomly selected sheep with polymeric valve was euthanized and the explanted valved stent was analyzed macroscopically and microscopically. Findings Implantation was successful in 9 sheep. Angiography at implantation showed all 9 prosthetic valves demonstrated orthotopic position and normal functionality. All 9 sheep survived at 4-week follow-up. Four-week follow-up revealed no evidence of valve stent dislocation or deformation and normal valvular and cardiac functionality. The cardiac catheter examination showed the peak-peak transvalvular pressure gradient of the polymeric valves was 11.9±5.0 mmHg, while that of two bovine pericardium valves were 11 and 17 mmHg. Gross morphology demonstrated good opening and closure characteristics. No thrombus or calcification was seen macroscopically. Conclusions This design of the novel ePTFE transcatheter pulmonary valve is safe and effective to deploy in sheep by hybrid approach, and the early valvular functionality is good. PMID:24926892

Polymeric Additives For Graphite/Epoxy Composites

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Nir, Z.

1990-01-01

Report describes experimental studies of properties of several graphite/epoxy composites containing polymeric additives as flexibilizing or toughening agents. Emphasizes effects of brominated polymeric additives (BPA's) with or without carboxy-terminated butadiene acrylonitrile rubber. Reviews effects of individual and combined additives on fracture toughnesses, environmental stabilities, hot/wet strengths, thermomechanical behaviors, and other mechanical properties of composites.

Environmental durability diagnostic for printed identification codes of polymer insulation for distribution pipelines

NASA Astrophysics Data System (ADS)

Zhuravleva, G. N.; Nagornova, I. V.; Kondratov, A. P.; Bablyuk, E. B.; Varepo, L. G.

2017-08-01

A research and modelling of weatherability and environmental durability of multilayer polymer insulation of both cable and pipelines with printed barcodes or color identification information were performed. It was proved that interlayer printing of identification codes in distribution pipelines insulation coatings provides high marking stability to light and atmospheric condensation. This allows to carry out their distant damage control. However, microbiological fouling of upper polymer layer hampers the distant damage pipelines identification. The color difference values and density changes of PE and PVC printed insolation due to weather and biological factors were defined.

Performance and Durability of Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna

2016-01-01

This presentation highlights advanced environmental barrier coating (EBC) and SiC-SiC Ceramic Matrix Composites (CMC) systems for next generation turbine engines. The emphasis will be placed on fundamental coating and CMC property evaluations; and the integrated system performance and degradation mechanisms in simulated laboratory turbine engine testing environments. Long term durability tests in laser rig simulated high heat flux the rmomechanical creep and fatigue loading conditions will also be presented. The results can help improve the future EBC-CMC system designs, validating the advanced EBC-CMC technologies for hot section turbine engine applications.

Advanced Environmental Barrier Coatings Developed for SiC/SiC Composite Vanes

NASA Technical Reports Server (NTRS)

Lee, Kang N.; Fox, Dennis S.; Eldridge, Jeffrey I.; Zhu, Dongming; Bansal, Narottam P.; Miller, Robert A.

2003-01-01

Ceramic components exhibit superior high-temperature strength and durability over conventional component materials in use today, signifying the potential to revolutionize gas turbine engine component technology. Silicon-carbide fiber-reinforced silicon carbide ceramic matrix composites (SiC/SiC CMCs) are prime candidates for the ceramic hotsection components of next-generation gas turbine engines. A key barrier to the realization of SiC/SiC CMC hot-section components is the environmental degradation of SiC/SiC CMCs in combustion environments. This is in the form of surface recession due to the volatilization of silica scale by water vapor. An external environmental barrier coating (EBC) is a logical approach to achieve protection and long-term durability.

Enhanced mechanical properties of low-surface energy thin films by simultaneous plasma polymerization of fluorine and epoxy containing polymers

NASA Astrophysics Data System (ADS)

Karaman, Mustafa; Uçar, Tuba

2016-01-01

Thin films of poly(2,2,3,4,4,4 hexafluorobutyl acrylate-glycidyl methacrylate) (P(HFBA-GMA) were deposited on different surfaces using an inductively coupled RF plasma reactor. Fluorinated polymer was used to impart hydrophobicity, whereas epoxy polymer was used for improved durability. The deposition at a low plasma power and temperature was suitable for the functionalization of fragile surfaces such as textile fabrics. The coated rough textile surfaces were found to be superhydrophobic with water contact angles greater than 150° due to the high retention of long fluorinated side chains. The hydrophobicity of the surfaces was observed to be stable after many exposures to ultrasonification tests, which is attributed to the mechanical durability of the films due to their epoxide functionality. FTIR and XPS analyses of the deposited films confirmed that the epoxide functionality of the polymers increased with increasing glycidyl methacrylate fraction in the reactor inlet. The modulus and hardness values of the films also increase with increasing epoxide functionality.

Transparent superwetting nanofilms with enhanced durability at model physiological condition

PubMed Central

Hwangbo, Sunghee; Heo, Jiwoong; Lin, Xiangde; Choi, Moonhyun; Hong, Jinkee

2016-01-01

There have been many studies on superwetting surfaces owing to the variety of their potential applications. There are some drawbacks to developing these films for biomedical applications, such as the fragility of the microscopic roughness feature that is vital to ensure superwettability. But, there are still only a few studies that have shown an enhanced durability of nanoscale superwetting films at certain extreme environment. In this study, we fabricated intrinsically stable superwetting films using the organosilicate based layer-by-layer (LbL) self-assembly method in order to control nano-sized roughness of the multilayer structures. In order to develop mechanically and chemically robust surfaces, we successfully introduced polymeric silsesquioxane as a building block for LbL assembly with desired fashion. Even in the case that the superhydrophobic outer layers were damaged, the films maintained their superhydrophobicity because of the hydrophobic nature of their inner layers. As a result, we successfully fabricated superwetting nano-films and evaluated their robustness and stability. PMID:26764164

Roofing research and standards development: Fourth volume. ASTM special technical publication 1349

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wallace, T.J.; Rossiter, W.J. Jr.

1999-07-01

As the roofing industry has stabilized, a broad variety of roof systems have found general acceptance by the building owners, architects, engineers, contractors, and others who select and install roofs. These roof systems include those based on conventional built-up membranes using glass and synthetic reinforcements, synthetic polymeric membranes using elastomers and thermoplastics, polymer-modified membranes, and sprayed polyurethane foam. ASTM Committee D8 on Roofing, Waterproofing, and Bituminous Materials has contributed significantly in many important ways to the roofing community's stabilization including issuing standard specifications to assist consumers in the selection and use of these systems. This is not surprising, as itmore » has always been among the purpose of D8 to provide standards to assist in the selection and use of low-sloped and steep roofing. The Committee's scope includes development of standards associated with application, inspection, maintenance, and analyses. Some of the issues facing the roofing community today--for example, enhanced system durability, better methods of material characterization, environmental impact, recycling of materials and systems, industry conversation to the S.I. system metric--readily fall within D8's scope. The availability of sound standard can contribute to the resolution of many of these issues.« less

A study on resistance to ultraviolet radiation of POSS-TiO2/epoxy nanocomposites

NASA Astrophysics Data System (ADS)

Peng, Dequn; Qin, Wei; Wu, Xiaohong

2015-06-01

Ultraviolet (UV) radiation is a severe space environmental factor, which is harmful to the durability of the polymeric materials of the spacecraft. For this reason, a novel POSS-TiO2/EP nanocomposite was synthesized by incorporating the POSS-TiO2 organic-inorganic hybrid into the epoxy (EP) resin. The effects of UV radiation on EP resin and on POSS-TiO2/EP nanocomposites were investigated in a ground-based simulator that simulates space radiation conditions. Compared with EP resin, the value of bend strength for 5.0 wt% POSS-TiO2/EP varied in a small range before and after UV radiation. Meanwhile, a typical tough feature was observed from the SEM photo for POSS-TiO2/EP nanocomposite after UV exposure. This result indicated that the POSS-TiO2/EP exhibited the excellent properties of anti-space ultraviolet radiation. The thermo gravimetric (TG) results showed that the addition of POSS-TiO2 improved the thermal-stability of EP resin matrix. The synthesized nanocomposites in this work could be used in the satellites to enhance their adaptability to the space environment and extend their service life.

Simulated Solar Flare X-Ray and Thermal Cycling Durability Evaluation of Hubble Space Telescope Thermal Control Candidate Replacement Materials

NASA Technical Reports Server (NTRS)

deGroh, Kim K.; Banks, Bruce A.; Sechkar, Edward A.; Scheiman, David A.

1998-01-01

During the Hubble Space Telescope (HST) second servicing mission (SM2), astronauts noticed that the multilayer insulation (MLI) covering the telescope was damaged. Large pieces of the outer layer of MLI (aluminized Teflon fluorinated ethylene propylene (Al-FEP)) were torn in several locations around the telescope. A piece of curled up Al-FEP was retrieved by the astronauts and was found to be severely embrittled, as witnessed by ground testing. Goddard Space Flight Center (GSFC) organized a HST MLI Failure Review Board (FRB) to determine the damage mechanism of FEP in the HST environment, and to recommend replacement insulation material to be installed on HST during the third servicing mission (SM3) in 1999. Candidate thermal control replacement materials were chosen by the FRB and tested for environmental durability under various exposures and durations. This paper describes durability testing of candidate materials which were exposed to charged particle radiation, simulated solar flare x-ray radiation and thermal cycling under load. Samples were evaluated for changes in solar absorptance and tear resistance. Descriptions of environmental exposures and durability evaluations of these materials are presented.

Creep and Environmental Durability of EBC/CMCs Under Imposed Thermal Gradient Conditions

NASA Technical Reports Server (NTRS)

Appleby, Matthew; Morscher, Gregory N.; Zhu, Dongming

2013-01-01

Interest in SiC fiber-reinforced SiC ceramic matrix composite (CMC) environmental barrier coating (EBC) systems for use in high temperature structural applications has prompted the need for characterization of material strength and creep performance under complex aerospace turbine engine environments. Stress-rupture tests have been performed on SiC/SiC composites systems, with varying fiber types and coating schemes to demonstrate material behavior under isothermal conditions. Further testing was conducted under exposure to thermal stress gradients to determine the effect on creep resistance and material durability. In order to understand the associated damage mechanisms, emphasis is placed on experimental techniques as well as implementation of non-destructive evaluation; including electrical resistivity monitoring. The influence of environmental and loading conditions on life-limiting material properties is shown.

Porous Structure Design of Polymeric Membranes for Gas Separation

DOE PAGES

Zhang, Jinshui; Schott, Jennifer Ann; Mahurin, Shannon Mark; ...

2017-04-04

High-performance polymeric membranes for gas separation are of interest for molecular-level separations in industrial-scale chemical, energy and environmental processes. To overcome the inherent trade-off relationship between permeability and selectivity, the creation of permanent microporosity in polymeric matrices is highly desirable because the porous structures can provide a high fractional free volume to facilitate gas transport through the dense layer. In this feature article, recent developments in the formation of porous polymeric membranes and potential strategies for pore structure design are reviewed.

Application of mercapto-silica polymerized high internal phase emulsions for the solid-phase extraction and preconcentration of trace lead(II).

PubMed

Su, Rihui; Ruan, Guihua; Chen, Zhengyi; Du, Fuyou; Li, Jianping

2015-12-01

A new class of solid-phase extraction column prepared with grafted mercapto-silica polymerized high internal phase emulsion particles was used for the preconcentration of trace lead. First, mercapto-silica polymerized high internal phase emulsion particles were synthesized by using high internal phase emulsion polymerization and carefully assembled in a polyethylene syringe column. The influences of various parameters including adsorption pH value, adsorption and desorption solvents, flow rate of the adsorption and desorption procedure were optimized, respectively, and the suitable uploading sample volumes, adsorption capacity, and reusability of solid phase extraction column were also investigated. Under the optimum conditions, Pb(2+) could be preconcentrated quantitatively over a wide pH range (2.0-5.0). In the presence of foreign ions, such as Na(+) , K(+) , Ca(2+) , Zn(2+) , Mg(2+) , Cu(2+) , Fe(2+) , Cd(2+) , Cl(-) and NO3 (-) , Pb(2+) could be recovered successfully. The prepared solid-phase extraction column performed with high stability and desirable durability, which allowed more than 100 replicate extractions without measurable changes of performance. The feasibility of the developed method was further validated by the extraction of Pb(2+) in rice samples. At three spiked levels of 40.0, 200 and 800 μg/kg, the average recoveries for Pb(2+) in rice samples ranged from 87.3 to 105.2%. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of a new class of flexible polymeric membranes for sensing, nanofiltration & cascaded separation

NASA Astrophysics Data System (ADS)

Du, Nian

The last decade has witnessed an explosion of interests in the science and technology of engineered nanomaterials. While the benefits of nanotechnology are widely publicized, the discussion about the transformation of nanomaterials in the environment, and their potential impacts on human health has just begun. Nanoscale particles, whether ultrafine, nano, engineered, intentional, or incidental, pose significant health effects. New approaches for environmental monitoring of nanomaterials at high sensitivity and in real-time are particularly needed. Since nanoparticles must be isolated from complex environmental and biological matrices, the most effective and simple method of isolating engineered nanomaterials from air or water is filtration. Hence the overall project objective of this work is to develop innovative methods that can simultaneously remove, detect and inactivate diverse nanostructured materials. At the center of the technology is a novel class of polymeric filters capable of simultaneously removing and detecting metal and metal oxide nanoparticles. This project reports the development of a new class of self-standing, flexible, phase-inverted, poly(amic) acid membranes with experimentally-controlled nanopores ranging from less than 10nm to greater than 100nm. Compared to most commercial filter membranes, phase-inverted PAA membranes were found to exhibit superior durability and higher efficiency. The filtration efficiency was ˜99.97% for a number of nanoparticles including Quantum Dots, TiO2, Au and Ag. This work also showed that PAA membranes could be used to separate mixtures of nanoparticles. Although the separation does not show much selectivity according to the NPs’ chemical composition, it shows the ability to separate efficiently based on nanoparticle size. PAA showed an excellent performance not only for nanoparticle isolation at sub-nanometer size ranges, but also as a platform for the detection of engineered nanoparticles at low ppb levels. We demonstrated the application of phase-inverted PAA membranes for quantitative detection of silver NPs using commercial food supplements, and the results were confirmed with AAS, SEM and EDS. Selective detection was achieved in the presence of high concentrations of other metal nanoparticles such as zinc oxide and gold NPs, and silver ions.

NASA's Advanced Environmental Barrier Coatings Development for SiC/SiC Ceramic Matrix Composites: Understanding Calcium Magnesium Alumino-Silicate (CMAS) Degradations and Resistance

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2014-01-01

Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is essential to the viability and reliability of the envisioned CMC engine component applications, ensuring integrated EBC-CMC system durability and designs are achievable for successful applications of the game-changing component technologies and lifing methodologies.This paper will emphasize recent NASA environmental barrier coating developments for SiCSiC turbine airfoil components, utilizing advanced coating compositions, state-of-the-art processing methods, and combined mechanical and environment testing and durability evaluations. The coating-CMC degradations in the engine fatigue-creep and operating environments are particularly complex; one of the important coating development aspects is to better understand engine environmental interactions and coating life debits, and we have particularly addressed the effect of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the durability of the environmental barrier coating systems, and how the temperature capability, stability and cyclic life of the candidate rare earth oxide and silicate coating systems will be impacted in the presence of the CMAS at high temperatures and under simulated heat flux conditions. Advanced environmental barrier coating systems, including HfO2-Si with rare earth dopant based bond coat systems, will be discussed for the performance improvements to achieve better temperature capability and CMAS resistance for future engine operating conditions.

Gene pyramiding enhances durable blast disease resistance in rice

PubMed Central

Fukuoka, Shuichi; Saka, Norikuni; Mizukami, Yuko; Koga, Hironori; Yamanouchi, Utako; Yoshioka, Yosuke; Hayashi, Nagao; Ebana, Kaworu; Mizobuchi, Ritsuko; Yano, Masahiro

2015-01-01

Effective control of blast, a devastating fungal disease of rice, would increase and stabilize worldwide food production. Resistance mediated by quantitative trait loci (QTLs), which usually have smaller individual effects than R-genes but confer broad-spectrum or non-race-specific resistance, is a promising alternative to less durable race-specific resistance for crop improvement, yet evidence that validates the impact of QTL combinations (pyramids) on the durability of plant disease resistance has been lacking. Here, we developed near-isogenic experimental lines representing all possible combinations of four QTL alleles from a durably resistant cultivar. These lines enabled us to evaluate the QTLs singly and in combination in a homogeneous genetic background. We present evidence that pyramiding QTL alleles, each controlling a different response to M. oryzae, confers strong, non-race-specific, environmentally stable resistance to blast disease. Our results suggest that this robust defence system provides durable resistance, thus avoiding an evolutionary “arms race” between a crop and its pathogen. PMID:25586962

Gene pyramiding enhances durable blast disease resistance in rice.

PubMed

Fukuoka, Shuichi; Saka, Norikuni; Mizukami, Yuko; Koga, Hironori; Yamanouchi, Utako; Yoshioka, Yosuke; Hayashi, Nagao; Ebana, Kaworu; Mizobuchi, Ritsuko; Yano, Masahiro

2015-01-14

Effective control of blast, a devastating fungal disease of rice, would increase and stabilize worldwide food production. Resistance mediated by quantitative trait loci (QTLs), which usually have smaller individual effects than R-genes but confer broad-spectrum or non-race-specific resistance, is a promising alternative to less durable race-specific resistance for crop improvement, yet evidence that validates the impact of QTL combinations (pyramids) on the durability of plant disease resistance has been lacking. Here, we developed near-isogenic experimental lines representing all possible combinations of four QTL alleles from a durably resistant cultivar. These lines enabled us to evaluate the QTLs singly and in combination in a homogeneous genetic background. We present evidence that pyramiding QTL alleles, each controlling a different response to M. oryzae, confers strong, non-race-specific, environmentally stable resistance to blast disease. Our results suggest that this robust defence system provides durable resistance, thus avoiding an evolutionary "arms race" between a crop and its pathogen.

Influence of Water on Tribological Properties of Wood-Polymer Composites

NASA Astrophysics Data System (ADS)

Mysiukiewicz, Olga; Sterzyński, Tomasz

2017-08-01

Utilization of ecological materials for appliances and products is one of the ways to achieve the goal of sustainability.Wood-polymer composites as a cheap, lightweight, durable and esthetic material has gained attention of scientists, engineers and consumers alike. Different kinds of polymeric matrices, plants used as the fillers, chemical of physical modifiers and processing technologies have already been widely studied. Nonetheless, surprisingly few information on Wood-Polymer Composites' tribology can be found. This paper is an attempt to fill this gap. Polypropylene-and poly(lactic acid)-based composites with varying wood flour content have been analyzed. The Brinell's hardness and coefficient of friction of the samples have been determined. In order to evaluate the influence of the moisture content on the tribological and mechanical properties of the composites, the samples have also been aged in water. The investigation revealed that polymeric composites filled with wood flour can present favorable coefficient of friction, compared to the neat resins. The results of our study can establish a good starting point for further investigation.

Patterned, highly stretchable and conductive nanofibrous PANI/PVDF strain sensors based on electrospinning and in situ polymerization.

PubMed

Yu, Gui-Feng; Yan, Xu; Yu, Miao; Jia, Meng-Yang; Pan, Wei; He, Xiao-Xiao; Han, Wen-Peng; Zhang, Zhi-Ming; Yu, Liang-Min; Long, Yun-Ze

2016-02-07

A facile fabrication strategy via electrospinning and followed by in situ polymerization to fabricate a patterned, highly stretchable, and conductive polyaniline/poly(vinylidene fluoride) (PANI/PVDF) nanofibrous membrane is reported. Owing to the patterned structure, the nanofibrous PANI/PVDF strain sensor can detect a strain up to 110%, for comparison, which is 2.6 times higher than the common nonwoven PANI/PVDF mat and much larger than the previously reported values (usually less than 15%). Meanwhile, the conductivity of the patterned strain sensor shows a linear response to the applied strain in a wide range from 0% to about 85%. Additionally, the patterned PANI/PVDF strain sensor can completely recover to its original electrical and mechanical values within a strain range of more than 22%, and exhibits good durability over 10,000 folding-unfolding tests. Furthermore, the strain sensor also can be used to detect finger motion. The results demonstrate promising application of the patterned nanofibrous membrane in flexible electronic fields.

Patterned, highly stretchable and conductive nanofibrous PANI/PVDF strain sensors based on electrospinning and in situ polymerization

NASA Astrophysics Data System (ADS)

Yu, Gui-Feng; Yan, Xu; Yu, Miao; Jia, Meng-Yang; Pan, Wei; He, Xiao-Xiao; Han, Wen-Peng; Zhang, Zhi-Ming; Yu, Liang-Min; Long, Yun-Ze

2016-01-01

A facile fabrication strategy via electrospinning and followed by in situ polymerization to fabricate a patterned, highly stretchable, and conductive polyaniline/poly(vinylidene fluoride) (PANI/PVDF) nanofibrous membrane is reported. Owing to the patterned structure, the nanofibrous PANI/PVDF strain sensor can detect a strain up to 110%, for comparison, which is 2.6 times higher than the common nonwoven PANI/PVDF mat and much larger than the previously reported values (usually less than 15%). Meanwhile, the conductivity of the patterned strain sensor shows a linear response to the applied strain in a wide range from 0% to about 85%. Additionally, the patterned PANI/PVDF strain sensor can completely recover to its original electrical and mechanical values within a strain range of more than 22%, and exhibits good durability over 10 000 folding-unfolding tests. Furthermore, the strain sensor also can be used to detect finger motion. The results demonstrate promising application of the patterned nanofibrous membrane in flexible electronic fields.A facile fabrication strategy via electrospinning and followed by in situ polymerization to fabricate a patterned, highly stretchable, and conductive polyaniline/poly(vinylidene fluoride) (PANI/PVDF) nanofibrous membrane is reported. Owing to the patterned structure, the nanofibrous PANI/PVDF strain sensor can detect a strain up to 110%, for comparison, which is 2.6 times higher than the common nonwoven PANI/PVDF mat and much larger than the previously reported values (usually less than 15%). Meanwhile, the conductivity of the patterned strain sensor shows a linear response to the applied strain in a wide range from 0% to about 85%. Additionally, the patterned PANI/PVDF strain sensor can completely recover to its original electrical and mechanical values within a strain range of more than 22%, and exhibits good durability over 10 000 folding-unfolding tests. Furthermore, the strain sensor also can be used to detect finger motion. The results demonstrate promising application of the patterned nanofibrous membrane in flexible electronic fields. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08618c

One-Pot Anchoring of Pd Nanoparticles on Nitrogen-Doped Carbon through Dopamine Self-Polymerization and Activity in the Electrocatalytic Methanol Oxidation Reaction.

PubMed

Li, Xin; Niu, Xiangheng; Zhang, Wenchi; He, Yanfang; Pan, Jianming; Yan, Yongsheng; Qiu, Fengxian

2017-03-09

Exploration of advanced electrocatalysts to promote the sluggish methanol oxidation reaction (MOR) is of vital importance for developing high efficiency and low-cost direct methanol fuel cells. Highly dispersed palladium nanoparticles (Pd NPs) anchored on a nitrogen-doped carbon support were fabricated using a facile one-pot dopamine self-polymerization mediated redox strategy, in which dopamine not only acted as a moderate reductant to induce the formation of Pd NPs during self-polymerization but was also the precursor of the nitrogen-doped carbon support for Pd. The synthesized hybrid features the following characteristics: 1) High dispersity of Pd NPs, which exposed a high abundance of active surfaces and sites for heterogeneous electrocatalysis; 2) metal-support interactions, which may affect the surface chemistry and electron distribution of active Pd NPs; 3) the Pd NPs were partially imbedded or encapsulated into the support, thus reducing the possible agglomeration of Pd NPs during cyclic measurements. The electrocatalyst with such favorable features provided higher mass activity (2.2 times that of commercial Pd/C) and better durability (reduced loss of activity during simulated frequent startup-shutdown operations) for the MOR in alkaline media. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel double-confined polymeric ionic liquids as sorbents for solid-phase microextraction with enhanced stability and durability in high-ionic-strength solution.

PubMed

Feng, Juanjuan; Sun, Min; Xu, Lili; Wang, Shuai; Liu, Xia; Jiang, Shengxiang

2012-12-14

Because of the occurrence of ion exchange between high-ionic-strength solution and anions of polymeric ionic liquids (PILs), PILs based solid-phase microextraction (SPME) fibers were rarely used in direct immersion mode to high-salt-added samples. In this work, a novel double-confined PIL sorbent was prepared by co-polymerization of cation and anion of 1-vinyl-3-octylimidzaolium p-styrenesulfonate (VOIm(+)SS(-)). The poly(VOIm(+)-SS(-)) was chemically bonded onto functionalized stainless steel wire via surface radical chain-transfer reaction. Stability of poly(VOIm(+)-SS(-)) in high-ionic-strength solution was investigated and compared with that of poly(1-vinyl-3-octylimidzaolium benzenesulfonate) (poly(VOIm(+)BS(-))) by elemental analysis of sulfur element, and results turned out that the poly(VOIm(+)-SS(-)) was more stable. Coupled to gas chromatography (GC), the poly(VOIm(+)-SS(-)) fiber was used to extract three sorts of compounds including anilines, phenols and phthalate esters in aqueous solution. The as-established method showed good linearity, low detection limits, and acceptable repeatability. The direct immersion SPME-GC method was applied to determine the model phthalate esters in bottled mineral water. The determination results were satisfactory. Copyright © 2012 Elsevier B.V. All rights reserved.

Environmental Barrier Coatings Having a YSZ Top Coat

NASA Technical Reports Server (NTRS)

Lee, Kang N.; Gray, Hugh (Technical Monitor)

2002-01-01

Environmental barrier coatings (EBCs) with a Si bond coat, a yttria-stabilized zirconia (YSZ) top coat, and various intermediate coats were investigated. EBCs were processed by atmospheric pressure plasma spraying. The EBC durability was determined by thermal cycling tests in water vapor at 1300 C and 1400 C, and in air at 1400 C and 1500 C. EBCs with a mullite (3Al2O3 (dot) 2SiO2) + BSAS (1 - xBaO (dot) xSrO (dot) Al2O3 (dot) 2SiO2) intermediate coat were more durable than EBCs with a mullite intermediate coat, while EBCs with a mullite/BSAS duplex intermediate coat resulted in inferior durability. The improvement with a mullite + BSAS intermediate coat was attributed to enhanced compliance of the intermediate coat due to the addition of a low modulus BSAS second phase. Mullite + BSAS/YSZ and BSAS/YSZ interfaces produced a low melting (less than 1400 C) reaction product, which is expected to degrade the EBC performance by increasing the thermal conductivity. EBCs with a mullite + BSAS / graded mullite + YSZ intermediate coat showed the best durability among the EBCs investigated in this study. This improvement was attributed to diffused CTE (Coefficient of Thermal Expansion) mismatch stress and improved chemical stability due to the compositionally graded mullite+YSZ layer.

Simulation of the synergistic low Earth orbit effects of vacuum thermal cycling, vacuum UV radiation, and atomic oxygen

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; Degroh, Kim K.; Stidham, Curtis R.; Stueber, Thomas J.; Dever, Therese M.; Rodriguez, Elvin; Terlep, Judith A.

1992-01-01

In order to assess the low Earth orbit (LEO) durability of candidate space materials, it is necessary to use ground laboratory facilities which provide LEO environmental effects. A facility combining vacuum thermal cycling and vacuum ultraviolet (VUV) radiation has been designed and constructed at NASA Lewis Research Center for this purpose. This facility can also be operated without the VUV lamps. An additional facility can be used to provide VUV exposure only. By utilizing these facilities, followed by atomic oxygen exposure in an RF plasma asher, the effects of the individual vacuum thermal cycling and VUV environments can be compared to the effect of the combined vacuum thermal cycling/VUV environment on the atomic oxygen durability of materials. The synergistic effects of simulated LEO environmental conditions on materials were evaluated by first exposing materials to vacuum thermal cycling, VUV, and vacuum thermal cycling/VUV environments followed by exposure to atomic oxygen in an RP plasma asher. Candidate space power materials such as atomic oxygen protected polyimides and solar concentrator mirrors were evaluated using these facilities. Characteristics of the Vacuum Thermal Cycling/VUV Exposure Facility which simulates the temperature sequences and solar ultraviolet radiation exposure that would be experienced by a spacecraft surface in LEO are discussed. Results of durability evaluations of some candidate space power materials to the simulated LEO environmental conditions will also be discussed. Such results have indicated that for some materials, atomic oxygen durability is affected by previous exposure to thermal cycling and/or VUV exposure.

Adaptive Evolution and Environmental Durability Jointly Structure Phylodynamic Patterns in Avian Influenza Viruses

PubMed Central

Roche, Benjamin; Drake, John M.; Brown, Justin; Stallknecht, David E.; Bedford, Trevor; Rohani, Pejman

2014-01-01

Avian influenza viruses (AIVs) have been pivotal to the origination of human pandemic strains. Despite their scientific and public health significance, however, there remains much to be understood about the ecology and evolution of AIVs in wild birds, where major pools of genetic diversity are generated and maintained. Here, we present comparative phylodynamic analyses of human and AIVs in North America, demonstrating (i) significantly higher standing genetic diversity and (ii) phylogenetic trees with a weaker signature of immune escape in AIVs than in human viruses. To explain these differences, we performed statistical analyses to quantify the relative contribution of several potential explanations. We found that HA genetic diversity in avian viruses is determined by a combination of factors, predominantly subtype-specific differences in host immune selective pressure and the ecology of transmission (in particular, the durability of subtypes in aquatic environments). Extending this analysis using a computational model demonstrated that virus durability may lead to long-term, indirect chains of transmission that, when coupled with a short host lifespan, can generate and maintain the observed high levels of genetic diversity. Further evidence in support of this novel finding was found by demonstrating an association between subtype-specific environmental durability and predicted phylogenetic signatures: genetic diversity, variation in phylogenetic tree branch lengths, and tree height. The conclusion that environmental transmission plays an important role in the evolutionary biology of avian influenza viruses—a manifestation of the “storage effect”—highlights the potentially unpredictable impact of wildlife reservoirs for future human pandemics and the need for improved understanding of the natural ecology of these viruses. PMID:25116957

Atomic-Oxygen-Durable and Electrically-Conductive CNT-POSS-Polyimide Flexible Films for Space Applications.

PubMed

Atar, Nurit; Grossman, Eitan; Gouzman, Irina; Bolker, Asaf; Murray, Vanessa J; Marshall, Brooks C; Qian, Min; Minton, Timothy K; Hanein, Yael

2015-06-10

In low Earth orbit (LEO), hazards such as atomic oxygen (AO) or electrostatic discharge (ESD) degrade polymeric materials, specifically, the extensively used polyimide (PI) Kapton. We prepared PI-based nanocomposite films that show both AO durability and ESD protection by incorporating polyhedral oligomeric silsesquioxane (POSS) and carbon nanotube (CNT) additives. The unique methods that are reported prevent CNT agglomeration and degradation of the CNT properties that are common in dispersion-based processes. The influence of the POSS content on the electrical, mechanical, and thermo-optical properties of the CNT-POSS-PI films was investigated and compared to those of control PI and CNT-PI films. CNT-POSS-PI films with 5 and 15 wt % POSS content exhibited sheet resistivities as low as 200 Ω/□, and these resistivities remained essentially unchanged after exposure to AO with a fluence of ∼2.3 × 10(20) O atoms cm(-2). CNT-POSS-PI films with 15 wt % POSS content exhibited an erosion yield of 4.8 × 10(-25) cm(3) O atom(-1) under 2.3 × 10(20) O atoms cm(-2) AO fluence, roughly one order of magnitude lower than that of pure PI films. The durability of the conductivity of the composite films was demonstrated by rolling film samples with a tight radius up to 300 times. The stability of the films to thermal cycling and ionizing radiation was also demonstrated. These properties make the prepared CNT-POSS-PI films with 15 wt % POSS content excellent candidates for applications where AO durability and electrical conductivity are required for flexible and thermally stable materials. Hence, they are suggested here for LEO applications such as the outer layers of spacecraft thermal blankets.

Fe3C nanoparticle decorated Fe/N doped graphene for efficient oxygen reduction reaction electrocatalysis

NASA Astrophysics Data System (ADS)

Niu, Yanli; Huang, Xiaoqin; Hu, Weihua

2016-11-01

Oxygen reduction reaction (ORR) electrocatalysts with high activity, low cost and good durability are crucial to promote the large-scale practical application of fuel cells. Particularly, iron carbide (Fe3C) supported on nitrogen-doped carbon has recently demonstrated compelling promise for ORR electrocatalysis. In this paper, we report the facile synthesis of mesoporous Fe/N-doped graphene with encapsulated Fe3C nanoparticles (Fe3C@Fe/N-graphene) and its superior ORR catalytic activity. This hybrid material was synthesized by the spontaneous oxidative polymerization of dopamine on graphene oxide (GO) sheets in the presence of iron ion, followed by thermal annealing in Argon (Ar) atmosphere. As-prepared material shows high ORR catalytic activity with overwhelming four-electron reduction pathway, long-term durability and high methanol tolerance in alkaline media. This work reports a facile method to synthesize promising ORR electrocatalysis with multiple components and hierarchical architecture, and may offer valuable insight into the underlying mechanism of Fe3C-boosted ORR activity of Fe/N doped carbon.

Preparation of antimicrobial MnO4--doped nylon-66 fibers with excellent laundering durability

NASA Astrophysics Data System (ADS)

Zhang, Mingxing; Gao, Qianhong; Yang, Chenguang; Pang, Lijuan; Wang, Honglong; Li, Rong; Xing, Zhe; Hu, Jiangtao; Wu, Guozhong

2017-11-01

A highly effective antimicrobial nylon 66 fiber doped with permanganate ions was prepared via a simultaneous irradiation induced graft polymerization. The physicochemical properties of the fibers were carefully characterized by various techniques, including Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy, revealing that permanganate ions (about 1.48 mmol/g) have been successfully loaded onto the surface of the nylon 66 fibers. The antimicrobial activity of the modified nylon 66 fibers against Staphylococcus aureus and Candida albicans were investigated. Accelerated laundering tests and tensile tests were conducted to access the effect of laundering on the antimicrobial activity and the mechanical property of the modified nylon 66 fibers, respectively. All results indicate that we have prepared a new highly effective antimicrobial nylon 66 fiber (almost a 100% reduction in the number of S. aureus and C. albicans colonies). Furthermore, the modified nylon 66 fibers are durable, maintaining antimicrobial resistance after 100 commercial or domestic launderings and retaining its excellent mechanical property during preparation and laundering.

Sustainable and long-time 'rejuvenation' of biomimetic water-repellent silica coating on polyester fabrics induced by rough mechanical abrasion.

PubMed

Rosu, Cornelia; Lin, Haisheng; Jiang, Lu; Breedveld, Victor; Hess, Dennis W

2018-04-15

The economical use of water-repellent coatings on polymeric materials in commercial and industrial applications is limited by their mechanical wear robustness and long-term durability. In this study, we demonstrate that polyethylene terephthalate (PET) fabric modified with inorganic, methyltrimethoxysilane (MTMS)-based coatings shows excellent resistance against various types of wear damage, thereby mimicking superhydrophobic biological materials. These features were facilitated by the rational design of coating processing that also enabled tunable hierarchical surface structure. A series of custom and standard testing protocols revealed that coating-to-substrate adhesion was remarkably high, as was the resistance to various mechanical abradents. The most intriguing characteristic observed during aging and abrasion cycles was the enhancement in non-wettability or 'rejuvenation' reflected by water droplet roll-off behavior, a characteristic of self-cleaning materials. Water-repellent properties of coated polyester were also enhanced by prolonged thermal annealing and were maintained after custom laundry. The developed technology offers opportunities to design low cost, durable and functional textiles for both indoor and outdoor applications. Copyright © 2018 Elsevier Inc. All rights reserved.

Advanced mortar coatings for cultural heritage protection. Durability towards prolonged UV and outdoor exposure.

PubMed

Pino, F; Fermo, P; La Russa, M; Ruffolo, S; Comite, V; Baghdachi, J; Pecchioni, E; Fratini, F; Cappelletti, G

2017-05-01

In the present work, two kinds of hybrid polymeric-inorganic coatings containing TiO 2 or SiO 2 particles and prepared starting from two commercial resins (Alpha®SI30 and Bluesil®BP9710) were developed and applied to two kinds of mortars (an air-hardening calcic lime mortar [ALM] and a natural hydraulic lime mortar [HLM]) to achieve better performances in terms of water repellence and consequently damage resistance. The two pure commercial resins were also applied for comparison purposes. Properties of the coated materials and their performance were studied using different techniques such as contact angle measurements, capillary absorption test, mercury intrusion porosimetry, surface free energy, colorimetric measurements and water vapour permeability tests. Tests were also performed to determine the weathering effects on both the commercial and the hybrid coatings in order to study their durability. Thus, exposures to UV radiation, to UV radiation/condensed water cycles and to a real polluted atmospheric environment have been performed. The effectiveness of the hybrid SiO 2 based coating was demonstrated, especially in the case of the HLM mortar.

Environmental Durability Issues for Solar Power Systems in Low Earth Orbit

NASA Technical Reports Server (NTRS)

Degroh, Kim K.; Banks, Bruce A.; Smith, Daniela C.

1994-01-01

Space solar power systems for use in the low Earth orbit (LEO) environment experience a variety of harsh environmental conditions. Materials used for solar power generation in LEO need to be durable to environmental threats such as atomic oxygen, ultraviolet (UV) radiation, thermal cycling, and micrometeoroid and debris impact. Another threat to LEO solar power performance is due to contamination from other spacecraft components. This paper gives an overview of these LEO environmental issues as they relate to space solar power system materials. Issues addressed include atomic oxygen erosion of organic materials, atomic oxygen undercutting of protective coatings, UV darkening of ceramics, UV embrittlement of Teflon, effects of thermal cycling on organic composites, and contamination due to silicone and organic materials. Specific examples of samples from the Long Duration Exposure Facility (LDEF) and materials returned from the first servicing mission of the Hubble Space Telescope (HST) are presented. Issues concerning ground laboratory facilities which simulate the LEO environment are discussed along with ground-to-space correlation issues.

Signal amplification strategies for DNA and protein detection based on polymeric nanocomposites and polymerization: A review.

PubMed

Zhou, Shaohong; Yuan, Liang; Hua, Xin; Xu, Lingling; Liu, Songqin

2015-06-02

Demand is increasing for ultrasensitive bioassays for disease diagnosis, environmental monitoring and other research areas. This requires novel signal amplification strategies to maximize the signal output. In this review, we focus on a series of significant signal amplification strategies based on polymeric nanocomposites and polymerization. Some common polymers are used as carriers to increase the local concentration of signal probes and/or biomolecules on their surfaces or in their interiors. Some polymers with special fluorescence and optical properties can efficiently transfer the excitation energy from a single site to the whole polymer backbone. This results in superior fluorescence signal amplification due to the resulting collective effort (integration of signal). Recent polymerization-based signal amplification strategies that employ atom transfer radical polymerization (ATRP) and photo-initiated polymerization are also summarized. Several distinctive applications of polymers in ultrasensitive bioanalysis are highlighted. Copyright © 2015 Elsevier B.V. All rights reserved.

Environmental Barrier Coatings for Turbine Engines: A Design and Performance Perspective

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Fox, Dennis S.; Ghosn, Louis; Smialek, James L.; Miller, Robert A.

2009-01-01

Ceramic thermal and environmental barrier coatings (TEBC) for SiC-based ceramics will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating long-term durability remains a major concern with the ever-increasing temperature, strength and stability requirements in engine high heat-flux combustion environments, especially for highly-loaded rotating turbine components. Advanced TEBC systems, including nano-composite based HfO2-aluminosilicate and rare earth silicate coatings are being developed and tested for higher temperature capable SiC/SiC ceramic matrix composite (CMC) turbine blade applications. This paper will emphasize coating composite and multilayer design approach and the resulting performance and durability in simulated engine high heat-flux, high stress and high pressure combustion environments. The advances in the environmental barrier coating development showed promise for future rotating CMC blade applications.

The Sit-and-Wait Hypothesis in Bacterial Pathogens: A Theoretical Study of Durability and Virulence.

PubMed

Wang, Liang; Liu, Zhanzhong; Dai, Shiyun; Yan, Jiawei; Wise, Michael J

2017-01-01

The intriguing sit-and-wait hypothesis predicts that bacterial durability in the external environment is positively correlated with their virulence. Since its first proposal in 1987, the hypothesis has been spurring debates in terms of its validity in the field of bacterial virulence. As a special case of the vector-borne transmission versus virulence tradeoff, where vector is now replaced by environmental longevity, there are only sporadic studies over the last three decades showing that environmental durability is possibly linked with virulence. However, no systematic study of these works is currently available and epidemiological analysis has not been updated for the sit-and-wait hypothesis since the publication of Walther and Ewald's (2004) review. In this article, we put experimental evidence, epidemiological data and theoretical analysis together to support the sit-and-wait hypothesis. According to the epidemiological data in terms of gain and loss of virulence (+/-) and durability (+/-) phenotypes, we classify bacteria into four groups, which are: sit-and-wait pathogens (++), vector-borne pathogens (+-), obligate-intracellular bacteria (--), and free-living bacteria (-+). After that, we dive into the abundant bacterial proteomic data with the assistance of bioinformatics techniques in order to investigate the two factors at molecular level thanks to the fast development of high-throughput sequencing technology. Sequences of durability-related genes sourced from Gene Ontology and UniProt databases and virulence factors collected from Virulence Factor Database are used to search 20 corresponding bacterial proteomes in batch mode for homologous sequences via the HMMER software package. Statistical analysis only identified a modest, and not statistically significant correlation between mortality and survival time for eight non-vector-borne bacteria with sit-and-wait potentials. Meanwhile, through between-group comparisons, bacteria with higher host-mortality are significantly more durable in the external environment. The results of bioinformatics analysis correspond well with epidemiological data, that is, non-vector-borne pathogens with sit-and-wait potentials have higher number of virulence and durability genes compared with other bacterial groups. However, the conclusions are constrained by the relatively small bacterial sample size and non-standardized experimental data.

The Sit-and-Wait Hypothesis in Bacterial Pathogens: A Theoretical Study of Durability and Virulence

PubMed Central

Wang, Liang; Liu, Zhanzhong; Dai, Shiyun; Yan, Jiawei; Wise, Michael J.

2017-01-01

The intriguing sit-and-wait hypothesis predicts that bacterial durability in the external environment is positively correlated with their virulence. Since its first proposal in 1987, the hypothesis has been spurring debates in terms of its validity in the field of bacterial virulence. As a special case of the vector-borne transmission versus virulence tradeoff, where vector is now replaced by environmental longevity, there are only sporadic studies over the last three decades showing that environmental durability is possibly linked with virulence. However, no systematic study of these works is currently available and epidemiological analysis has not been updated for the sit-and-wait hypothesis since the publication of Walther and Ewald’s (2004) review. In this article, we put experimental evidence, epidemiological data and theoretical analysis together to support the sit-and-wait hypothesis. According to the epidemiological data in terms of gain and loss of virulence (+/-) and durability (+/-) phenotypes, we classify bacteria into four groups, which are: sit-and-wait pathogens (++), vector-borne pathogens (+-), obligate-intracellular bacteria (--), and free-living bacteria (-+). After that, we dive into the abundant bacterial proteomic data with the assistance of bioinformatics techniques in order to investigate the two factors at molecular level thanks to the fast development of high-throughput sequencing technology. Sequences of durability-related genes sourced from Gene Ontology and UniProt databases and virulence factors collected from Virulence Factor Database are used to search 20 corresponding bacterial proteomes in batch mode for homologous sequences via the HMMER software package. Statistical analysis only identified a modest, and not statistically significant correlation between mortality and survival time for eight non-vector-borne bacteria with sit-and-wait potentials. Meanwhile, through between-group comparisons, bacteria with higher host-mortality are significantly more durable in the external environment. The results of bioinformatics analysis correspond well with epidemiological data, that is, non-vector-borne pathogens with sit-and-wait potentials have higher number of virulence and durability genes compared with other bacterial groups. However, the conclusions are constrained by the relatively small bacterial sample size and non-standardized experimental data. PMID:29209284

40 CFR 721.9485 - Dimer acid/polymerized rosin amidoamine reaction product (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... amidoamine reaction product (generic). 721.9485 Section 721.9485 Protection of Environment ENVIRONMENTAL... reaction product (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as Dimer acid/polymerized rosin amidoamine reaction product (PMN...

40 CFR 721.9485 - Dimer acid/polymerized rosin amidoamine reaction product (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... amidoamine reaction product (generic). 721.9485 Section 721.9485 Protection of Environment ENVIRONMENTAL... reaction product (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as Dimer acid/polymerized rosin amidoamine reaction product (PMN...

Polymeric molecular sieve membranes via in situ cross-linking of non-porous polymer membrane templates.

PubMed

Qiao, Zhen-An; Chai, Song-Hai; Nelson, Kimberly; Bi, Zhonghe; Chen, Jihua; Mahurin, Shannon M; Zhu, Xiang; Dai, Sheng

2014-04-16

High-performance polymeric membranes for gas separation are attractive for molecular-level separations in industrial-scale chemical, energy and environmental processes. Molecular sieving materials are widely regarded as the next-generation membranes to simultaneously achieve high permeability and selectivity. However, most polymeric molecular sieve membranes are based on a few solution-processable polymers such as polymers of intrinsic microporosity. Here we report an in situ cross-linking strategy for the preparation of polymeric molecular sieve membranes with hierarchical and tailorable porosity. These membranes demonstrate exceptional performance as molecular sieves with high gas permeabilities and selectivities for smaller gas molecules, such as carbon dioxide and oxygen, over larger molecules such as nitrogen. Hence, these membranes have potential for large-scale gas separations of commercial and environmental relevance. Moreover, this strategy could provide a possible alternative to 'classical' methods for the preparation of porous membranes and, in some cases, the only viable synthetic route towards certain membranes.

Determination of Ten Macrolide Drugs in Environmental Water Using Molecularly Imprinted Solid-Phase Extraction Coupled with Liquid Chromatography-Tandem Mass Spectrometry.

PubMed

Song, Xuqin; Zhou, Tong; Li, Jiufeng; Zhang, Meiyu; Xie, Jingmeng; He, Limin

2018-05-14

With the extensive application of antibiotics in livestock, their contamination of the aquatic environment has received more attention. Molecularly imprinted polymer (MIP), as an eco-friendly and durable solid-phase extraction material, has shown great potential for the separation and enrichment of antibiotics in water. This study aims at developing a practical and economical method based on molecularly imprinted solid phase extraction (MISPE) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for simultaneously detecting ten macrolide drugs in different sources of water samples. The MIP was synthesized by bulk polymerization using tylosin as the template and methacrylic acid as the functional monomer. The MIP exhibited a favorable load-bearing capacity for water (>90 mL), which is more than triple that of non-molecularly imprinted polymers (NIP). The mean recoveries of macrolides at four spiked concentration levels (limit of quantification, 40, 100, and 400 ng/L) were 62.6⁻100.9%, with intra-day and inter-day relative standard deviations below 12.6%. The limit of detection and limit of quantification were 1.0⁻15.0 ng/L and 3.0⁻40.0 ng/L, respectively. Finally, the proposed method was successfully applied to the analysis of real water samples.

EarthScore: Your Personal Environmental Audit & Guide.

ERIC Educational Resources Information Center

Lotter, Donald W.

This book is designed to permit environmentally-conscious individuals to quantify the impact on the biosphere of their actions in the following areas: Home/household energy use; water use; transportation; consumerism (durable goods, foods and agricultural products, paper and forest products); toxics; waste, packaging, single-use items, and…

CMC Research at NASA Glenn in 2015: Recent Progress and Plans

NASA Technical Reports Server (NTRS)

Grady, Joseph E.

2015-01-01

As part of NASAs Aeronautical Sciences project, Glenn Research Center has developed advanced fiber and matrix constituents for a 2700F CMC for turbine engine applications. Fiber and matrix development and characterization will be reviewed. Resulting improvements in CMC mechanical properties and durability will be summarized. Plans for 2015 will be described, including development and validation of models predicting effects of the engine environment on durability of SiC/SiC composites with Environmental Barrier Coatings

Evaluation of high temperature structural adhesives for extended service

NASA Technical Reports Server (NTRS)

Hill, S. G.; Peters, P. D.; Hendricks, C. L.

1982-01-01

The evaluation, selection, and demonstration of structural adhesive systems for supersonic cruise research applications, and establishment of environmental durability of selected systems for up to 20,000 hours is described. Ten candidate adhesives were initially evaluated. During screening and evaluation, these candidates were narrowed to three of the most promising for environmental durability testing. The three adhesives were LARC-13, PPQ, and NR056X. The LARC-13 was eliminated because of a lack of stability at 505 K. The NRO56X was removed from the market. The LARC-TPI was added after preliminary evaluation and an abbreviated screening test. Only PPQ and LARC-TPI remained as the reasonable candidates late into the durability testing. Large area bond panels were fabricated to demonstrate the processibility of the selected systems. Specifications were prepared to assure control over critical material and process parameters. Surface characterization concentrated primarily upon titanium surface treatments of 10 volt chronic acid anodize, 5 volt chromic acid anodize and PASA-JELL. Failure analysis was conducted on lap shear adhesive bond failures which occurred in PPQ and LARC-13 test specimens after 10,000 hours at 505 K.

Eco-friendly GGBS Concrete: A State-of-The-Art Review

NASA Astrophysics Data System (ADS)

Saranya, P.; Nagarajan, Praveen; Shashikala, A. P.

2018-03-01

Concrete is the most commonly used material in the construction industry in which cement is its vital ingredient. Although the advantages of concrete are many, there are side effects leading to environmental issues. The manufacturing process of cement emits considerable amount of carbon dioxide (CO2). Therefore is an urgent need to reduce the usage of cement. Ground Granulated Blast furnace Slag (GGBS) is a by-product from steel industry. It has good structural and durable properties with less environmental effects. This paper critically reviews the literatures available on GGBS used in cement concrete. In this paper, the literature available on GGBS are grouped into engineering properties of GGBS concrete, hydraulic action of GGBS in concrete, durability properties of GGBS concrete, self- compacting GGBS concrete and ultrafine GGBS are highlighted. From the review of literature, it was found that the use of GGBS in concrete construction will be eco-friendly and economical. The optimum percentage of replacement of cement by GGBS lies between 40 - 45 % by weight. New materials that can be added in addition to GGBS for getting better strength and durability also highlighted.

Drug-eluting stents and acute myocardial infarction: A lethal combination or friends?

PubMed Central

Otsuki, Shuji; Sabaté, Manel

2014-01-01

Primary percutaneous coronary intervention is the preferred reperfusion strategy for patients presenting with ST-segment elevation myocardial infarction (STEMI). First generation drug-eluting stents (DES), (sirolimus drug-eluting stents and paclitaxel drug-eluting stents), reduce the risk of restenosis and target vessel revascularization compared to bare metal stents. However, stent thrombosis emerged as a major safety concern with first generation DES. In response to these safety issues, second generation DES were developed with different drugs, improved stent platforms and more biocompatible durable or bioabsorbable polymeric coating. This article presents an overview of safety and efficacy of the first and second generation DES in STEMI. PMID:25276295

Dye foils with increased durability for passive Q-switching in a 1064 nm laser

NASA Astrophysics Data System (ADS)

Mierczyk, Z.; Kwasny, M.; Czeszko, J.

The results of spectral gel permeation chromatography and differential thermal analysis investigations of structures of dye foils consisting of bis-(4-dimethyl-amino-dithio-benzil)-nickel dye suspended in polymethylmethacrylate matrix, to be used for passive Q-switching in a 1064 nm laser, are reported. Results of experimental measurements and of numerical calculations of thermal and generating properties, and of the endurance of passive foil type Q-switches in the resonator of YAG:Nd(3+) laser are also presented. Optimization of polymerization conditions has enabled the production of dye foils with high thermal and photochemical resistance, which give stable operation of a giant pulsed laser.

Optimisation structurale de dalles de chaussees en beton jointees avec des goujons en materiaux composites en Polymeres Renforces de Fibres de Verre (PRFV)

NASA Astrophysics Data System (ADS)

Bricola, Julien

In Quebec, the majority of the road network was built in the 60's - 70's and show obvious signs of ageing. Moreover, the increase of road traffic and the rigorous weather conditions, render the maintenance and the exploitation of roads in this Northern American part quite difficult. Indeed, these environmental conditions cause severe damages for roads, especially in winter. The degradation factor of the jointed rigid pavement is intensified by the highway salt. So, the phenomena of deteriorations appears mainly by the corrosion of the steel at the joints (structural elements) guaranteeing the durability of roads. The jointed rigid pavements or "short jointed pavements" are still mainly sized with steel dowels placed at the lining of joints. One of the main functions of these structures is to control the formation of cracking due to the thermal and environmental conditions. In order to reduce these , disorders, the Ministry of Transport of Quebec (MTQ) turned towards new techniques and innovative materials to ensure the longevity of roads. With the rapid evolution of specific methods and knowledge in roads design, joined with technologies and new products, the MTQ emphasizes the research and development. That way, advanced techniques and diverse technologies in the Quebecois context are settled. As a matter of fact, one of the axes of these development researches concerns the composite materials which have recently been given good results in the civil engineering area. That is why Glass Fibre-Reinforced Polymer (GFRP) dowels bars appear as a solution to the steel corrosion. In fact, they provide better durability with lower costs: the increase of service life as well as the decrease of maintenance persons and traffics impac. Thus, this project proposes an optimization of structural design of GFRP dowels for transverse jointed highway pavement slabs, also keeping in mind their use in new projects. The GFRP dowels which are given in this essay are made by the Pultrall Inc. Company from Thetford Mines (Quebec, Canada). The resin used for the polymer materials is only vinylester resin and the dowels have diameters going from 28.6 mm to 34.9 mm. Finally, only a stiff base is used for the road, its particularity is the modulus of subgrade reaction. Keywords: concrete pavement, dowelled slab, jointed concrete pavement, GFRP dowels, optimization, structural, design .

Creep of Hi-Nicalon S Ceramic Fiber Tows at Elevated Temperature in Air and in Steam

DTIC Science & Technology

2012-03-22

temperature and environmental effects is a critical factor in development of composites with load carrying capacity and environmental durability...applications, including aircraft jet engines, gas turbines for electrical power/steam cogeneration , as well as nuclear power plant components. It is

Ground-Laboratory to In-Space Atomic Oxygen Correlation for the PEACE Polymers

NASA Astrophysics Data System (ADS)

Stambler, Arielle H.; Inoshita, Karen E.; Roberts, Lily M.; Barbagallo, Claire E.; de Groh, Kim K.; Banks, Bruce A.

2009-01-01

The Materials International Space Station Experiment 2 (MISSE 2) Polymer Erosion and Contamination Experiment (PEACE) polymers were exposed to the environment of low Earth orbit (LEO) for 3.95 years from 2001 to 2005. There were forty-one different PEACE polymers, which were flown on the exterior of the International Space Station (ISS) in order to determine their atomic oxygen erosion yields. In LEO, atomic oxygen is an environmental durability threat, particularly for long duration mission exposures. Although space flight experiments, such as the MISSE 2 PEACE experiment, are ideal for determining LEO environmental durability of spacecraft materials, ground-laboratory testing is often relied upon for durability evaluation and prediction. Unfortunately, significant differences exist between LEO atomic oxygen exposure and atomic oxygen exposure in ground-laboratory facilities. These differences include variations in species, energies, thermal exposures and radiation exposures, all of which may result in different reactions and erosion rates. In an effort to improve the accuracy of ground-based durability testing, ground-laboratory to in-space atomic oxygen correlation experiments have been conducted. In these tests, the atomic oxygen erosion yields of the PEACE polymers were determined relative to Kapton H using a radio-frequency (RF) plasma asher (operated on air). The asher erosion yields were compared to the MISSE 2 PEACE erosion yields to determine the correlation between erosion rates in the two environments. This paper provides a summary of the MISSE 2 PEACE experiment; it reviews the specific polymers tested as well as the techniques used to determine erosion yield in the asher, and it provides a correlation between the space and ground-laboratory erosion yield values. Using the PEACE polymers' asher to in-space erosion yield ratios will allow more accurate in-space materials performance predictions to be made based on plasma asher durability evaluation.

Life cycle environmental evaluation of kettles: Recommendations for the development of eco-design regulations in the European Union.

PubMed

Gallego-Schmid, Alejandro; Jeswani, Harish Kumar; Mendoza, Joan Manuel F; Azapagic, Adisa

2018-06-01

Between 117 and 200 million kettles are used in the European Union (EU) every year. However, the full environmental impacts of kettles remain largely unknown. This paper presents a comprehensive life cycle assessment of conventional plastic and metallic kettles in comparison with eco-kettles. The results show that the use stage contributes 80% to the impacts. For this reason, the eco-kettle has over 30% lower environmental impacts due to a greater water efficiency and related lower energy consumption. These results have been extrapolated to the EU level to consider the implications for proposed eco-design regulations. For these purposes, the effects on the impacts of durability of kettles and improvements in their energy and water efficiency have been assessed as they have been identified as two key parameters in the proposed regulations. The results suggest that increasing the current average durability from 4.4 to seven years would reduce the impacts by less than 5%. Thus, improving durability is not a key issue for improving the environmental performance of kettles and does not justify the need for an eco-design regulation based exclusively on it. However, improvements in water and energy efficiency through eco-design can bring relevant environmental savings. Boiling the exact amount of water needed would reduce the impacts by around a third and using water temperature control by further 2%-5%. The study has also considered the effects of reducing significantly the number of kettles in use after the UK (large user of kettles) leaves the EU and reducing the excess water typically boiled by the consumer. Even under these circumstances, the environmental savings justify the development of a specific EU eco-design regulation for kettles. However, consumer engagement will be key to the implementation and achievement of the expected environmental benefits. Copyright © 2017 Elsevier B.V. All rights reserved.

Refractory Oxide Coatings on Sic Ceramics

NASA Technical Reports Server (NTRS)

Lee, Kang N.; Jacobson, Nathan S.; Miller, Robert A.

1994-01-01

Silicon carbide with a refractory oxide coating is potentially a very attractive ceramic system. It offers the desirable mechanical and physical properties of SiC and the environmental durability of a refractory oxide. The development of a thermal shock resistant plasma-sprayed mullite coating on SiC is discussed. The durability of the mullite/SiC in oxidizing, reducing, and molten salt environments is discussed. In general, this system exhibits better behavior than uncoated SiC. Areas for further developments are discussed.

Environmental durability of electroplated black chromium

NASA Technical Reports Server (NTRS)

Lowery, J. R.

1981-01-01

A study was undertaken to determine the durability of nickel-black chromium plated aluminum in an outdoor rural industrial, and seacoast environment. Test panels were exposed to these environments for 60, 36, and 13 months, respectively. The results of this study showed that no significant optical degradation occurred from exposure to either of these environments, although a considerable amount of corrosion occurred on the panels exposed to the seacoast environment. The rural and industrial atmosphere produced only a slight amount of corrosion on test panels.

CMC Research at NASA Glenn in 2016: Recent Progress and Plans

NASA Technical Reports Server (NTRS)

Grady, Joseph E.

2016-01-01

As part of NASA's Aeronautical Sciences project, Glenn Research Center has developed advanced fiber and matrix constituents for a 2700 degrees Fahrenheit CMC (Ceramic Matrix Composite) for turbine engine applications. Fiber and matrix development and characterization will be reviewed. Resulting improvements in CMC mechanical properties and durability will be summarized. Plans for 2015 will be described, including development and validation of models predicting effects of the engine environment on durability of SiCSiC composites with Environmental Barrier Coatings (EBCs).

Antibacterial inorganic-organic hybrid coatings on stainless steel via consecutive surface-initiated atom transfer radical polymerization for biocorrosion prevention.

PubMed

Yuan, S J; Pehkonen, S O; Ting, Y P; Neoh, K G; Kang, E T

2010-05-04

To enhance the corrosion resistance of stainless steel (SS) and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, well-defined inorganic-organic hybrid coatings, consisting of a polysilsesquioxane inner layer and quaternized poly(2-(dimethyamino)ethyl methacrylate) (P(DMAEMA)) outer blocks, were prepared via successive surface-initiated atom transfer radical polymerization (ATRP) of 3-(trimethoxysilyl)propyl methacrylate (TMSPMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA). The cross-linked P(TMASPMA), or polysilsesquioxane, inner layer provided a durable and resistant coating to electrolytes. The pendant tertiary amino groups of the P(DMAEMA) outer block were quaternized with alkyl halide to produce a high concentration of quaternary ammonium groups with biocidal functionality. The so-synthesized inorganic-organic hybrid coatings on the SS substrates exhibited good anticorrosion and antibacterial effects and inhibited biocorrosion induced by sulfate-reducing bacteria (SRB) in seawater media, as revealed by antibacterial assay and electrochemical analyses, and they are potentially useful to steel-based equipment under harsh industrial and marine environments.

Changes in mechanical properties and morphology of elastomer coatings after immersion in salt solutions

NASA Astrophysics Data System (ADS)

Terán Arce, Fernando; Avci, Recep; Beech, Iwona; Cooksey, Keith; Wigglesworth-Cooksey, Barbara

2004-03-01

RTV11 (^TM GE Silicones) and Intersleek (^TM International Paints) are two elastomers of considerable significance to the navy and maritime industry for their application as fouling release coatings. Both materials are composed of polymeric matrices with embedded filler particles, which provide increased strength and durability to the elastomer. Using Atomic force microscopy (AFM), surface and bulk analysis techniques, we have found surface regions with microelastic properties, which correlate with the locations of filler particles inside the coatings. These particles are able to undergo elastic displacements of hundreds of nm inside the polymeric matrix during compression by the AFM tip. While elastic properties of Intersleek remain largely unchanged after immersion in salt solutions, roughening, embrittlement and stiffening occurs in RTV11 coatings depending on the amount of curing agent and humidity used during preparation and curing, respectively. Interestingly, such transformations are absent after immersion in pure water. In particle free regions, elastic moduli of RTV11 take values of 2 - 3 MPa before immersion in salt solutions. After immersion, those values increase 5 - 10 times.

Microfluidic Valves Made From Polymerized Polyethylene Glycol Diacrylate

PubMed Central

Rogers, Chad I.; Oxborrow, Joseph B.; Anderson, Ryan R.; Tsai, Long-Fang; Nordin, Gregory P.; Woolley, Adam T.

2013-01-01

Pneumatically actuated, non-elastomeric membrane valves fabricated from polymerized polyethylene glycol diacrylate (poly-PEGDA) have been characterized for temporal response, valve closure, and long-term durability. A ~100 ms valve opening time and a ~20 ms closure time offer valve operation as fast as 8 Hz with potential for further improvement. Comparison of circular and rectangular valve geometries indicates that the surface area for membrane interaction in the valve region is important for valve performance. After initial fabrication, the fluid pressure required to open a closed circular valve is ~50 kPa higher than the control pressure holding the valve closed. However, after ~1000 actuations to reconfigure polymer chains and increase elasticity in the membrane, the fluid pressure required to open a valve becomes the same as the control pressure holding the valve closed. After these initial conditioning actuations, poly-PEGDA valves show considerable robustness with no change in effective operation after 115,000 actuations. Such valves constructed from non-adsorptive poly-PEGDA could also find use as pumps, for application in small volume assays interfaced with biosensors or impedance detection, for example. PMID:24357897

Characterization of γ-radiation induced polymerization in ethyl methacrylate and methyl acrylate monomers solutions

NASA Astrophysics Data System (ADS)

Baccaro, Stefania; Casieri, Cinzia; Cemmi, Alessia; Chiarini, Marco; D'Aiuto, Virginia; Tortora, Mariagrazia

2017-12-01

The present work is focused on the γ-radiation induced polymerization of ethyl methacrylate (EMA) and methyl acrylate (MA) monomers mixture to obtain a co-polymer with specific features. The effect of the irradiation parameters (radiation absorbed dose, dose rate) and of the environmental atmosphere on the features of the final products was investigated. Attenuated Total Reflectance - Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Nuclear Magnetic Resonance high-resolution analyses of hydrogen and carbon nuclei (1H and 13C NMR) were applied to follow the γ-induced modifications by monitoring the co-polymerization process and allowed the irradiation parameters optimization. Diffusion-Ordered NMR (DOSY-NMR) data were used to evaluate the co-polymers polydispersity and polymerization degree. Since the last parameter is strongly influenced by the γ radiation and environmental conditions, a comparison among samples prepared and irradiated in air and under nitrogen atmosphere was carried out. In presence of oxygen, higher radiation was required to obtain a full solid co-polymer since a partial amount of energy released to the samples was involved in competitive processes, i.e. oxygen-containing free radicals formation and primary radicals recombination. Irrespectively to the environmental atmosphere, more homogeneous samples in term of polymerization degree dispersion was achieved at lower dose rates. At radiation absorbed doses higher than those needed for the formation of the co-polymer, while in case of samples irradiated in air heavy depolymerization was verified, a sensible increase of the samples stability was attained if the irradiation was performed under nitrogen atmosphere.

Moral Spaces, the Struggle for an Intergenerational Environmental Ethics and the Social Ecology of Families: An "Other" Form of Environmental Education

ERIC Educational Resources Information Center

Payne, Phillip G.

2010-01-01

"Green families" in Australia were studied so as to shed light on how a more durable, everyday environmental ethic and ecopolitic might slowly be enacted in the intimacy of the home "place" over an extended period of time in rapidly changing socio-cultural-ecological conditions. Of particular interest to this study of the green…

MSW fly ash stabilized with coal ash for geotechnical application.

PubMed

Kamon, M; Katsumi, T; Sano, Y

2000-09-15

The solidification and stabilization of municipal solid waste (MSW) fly ash for the purpose of minimizing the geo-environmental impact caused by toxic heavy metals as well as ensuring engineering safety (strength and soaking durability) are experimentally evaluated. The mixtures of MSW fly ash stabilized with cement and fluidized bed combustion coal fly ash (FCA) were used for unconfined compressive strength tests, leachate tests, and soaking tests. The behavior of soluble salts contained in the MSW fly ash significantly affects strength development, soaking durability, and the hardening reaction of the stabilized MSW fly ash mixtures. The cement stabilization of the MSW fly ash does not have enough effect on strength development and soaking durability. The addition of cement only contributes to the containment of heavy metals due to the high level of alkalinity. When using FCA as a stabilizing agent for MSW fly ash, the mixture exhibits high strength and durability. However, the Cd leachate cannot be prevented in the early stages of curing. Using a combination of cement and FCA as a MSW fly ash stabilizer can attain high strength, high soaking durability, and the containment of heavy metals. The stabilized MSW fly ash with cement and FCA can be practically applied to embankments.

Advanced Oxide Material Systems For 1650 C Thermal/Environmental Barrier Coating Applications

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Fox, Dennis S.; Bansal, Narottam P.; Miller, Robert A.

2004-01-01

Advanced thermal/environmental barrier coatings (T/EBCs) are being developed for low emission SiC/SiC ceramic matrix composite (CMC) combustor and vane applications to extend the CMC liner and vane temperature capability to 1650 C (3000 F) in oxidizing and water-vapor containing combustion environments. The 1650 C T/EBC system is required to have better thermal stability, lower thermal conductivity, and improved sintering and thermal stress resistance than current coating systems. In this paper, the thermal conductivity, water vapor stability and cyclic durability of selected candidate zirconia-/hafnia-, pyrochlore- and magnetoplumbite-based T/EBC materials are evaluated. The test results have been used to downselect the T/EBC coating materials, and help demonstrate advanced 1650OC coatings feasibility with long-term cyclic durability.

Environmental Durability and Stress Rupture of EBC/CMCs

NASA Technical Reports Server (NTRS)

Appleby, Matthew; Morscher, Gregory N.; Zhu, Dongming

2012-01-01

This research focuses on the strength and creep performance of SiC fiber-reinforced SiC ceramic matrix composite (CMC) environmental barrier coating (EBC) systems under complex simulated engine environments. Tensile-strength and stress-rupture testing was conducted to illustrate the material properties under isothermal and thermal gradient conditions. To determine material durability, further testing was conducted under exposure to thermal cycling, thermal gradients and simulated combustion environments. Emphasis is placed on experimental techniques as well as implementation of non-destructive evaluation, including modal acoustic emission and electrical resistivity monitoring, to characterize strength degradation and damage mechanisms. Currently, little is known about the behavior of EBC-CMCs under these conditions; consequently, this work will prove invaluable in the development of structural components for use in high temperature applications.

Examining the Durability of Environmental Education Self-Efficacy Beliefs in Preservice Teaching

ERIC Educational Resources Information Center

Richardson, Greer M.; Liang, Ling L.; Wake, Donna G.

2014-01-01

This research examined the outcome of a year two intervention which aligned two instructional contexts, to impact preservice teachers' Environmental Education (EE) self-efficacy beliefs and their use of inquiry-based instruction. The intervention immersed candidates in inquiry-based pedagogies and EE content across a science content course and a…

FAA/NASA International Symposium on Advanced Structural Integrity Methods for Airframe Durability and Damage Tolerance

NASA Technical Reports Server (NTRS)

Harris, Charles E. (Editor)

1994-01-01

International technical experts in durability and damage tolerance of metallic airframe structures were assembled to present and discuss recent research findings and the development of advanced design and analysis methods, structural concepts, and advanced materials. The symposium focused on the dissemination of new knowledge and the peer-review of progress on the development of advanced methodologies. Papers were presented on: structural concepts for enhanced durability, damage tolerance, and maintainability; new metallic alloys and processing technology; fatigue crack initiation and small crack effects; fatigue crack growth models; fracture mechanics failure, criteria for ductile materials; structural mechanics methodology for residual strength and life prediction; development of flight load spectra for design and testing; and advanced approaches to resist corrosion and environmentally assisted fatigue.

A study of the durability of beryllium rocket engines. [space shuttle reaction control system

NASA Technical Reports Server (NTRS)

Paster, R. D.; French, G. C.

1974-01-01

An experimental test program was performed to demonstrate the durability of a beryllium INTEREGEN rocket engine when operating under conditions simulating the space shuttle reaction control system. A vibration simulator was exposed to the equivalent of 100 missions of X, Y, and Z axes random vibration to demonstrate the integrity of the recently developed injector-to-chamber braze joint. An off-limits engine was hot fired under extreme conditions of mixture ratio, chamber pressure, and orifice plugging. A durability engine was exposed to six environmental cycles interspersed with hot-fire tests without intermediate cleaning, service, or maintenance. Results from this program indicate the ability of the beryllium INTEREGEN engine concept to meet the operational requirements of the space shuttle reaction control system.

Overview of CMC (Ceramic Matrix Composite) Research at the NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Kiser, J. Douglas; Grady, Joseph E.; Bhatt, Ramakrishna T.; Wiesner, Valerie L.; Zhu, Dongming

2016-01-01

In support of NASAs Aeronautics Research Mission, the Glenn Research Center has developed and assessed various constituents for a high temperature (2700F) SiCSiC CMC system for turbine engine applications. Combinations of highly creep-resistant SiC fibers, advanced 3D weaves, durable environmental barrier coatings (EBCs), and a 2700F-capable hybrid SiC matrix are being developed evaluated. The resulting improvements in CMC mechanical properties and durability will be summarized. The development and validation of models for predicting the effects of the environment on the durability of CMCs and EBCs and other operating-environment challenges including the effect of CMAS (calcium magnesium aluminosilicate) degradation of EBCs will be discussed. Progress toward the development of CMC joining technology for 2400F joint applications will also be reviewed.

Optical Analysis of Transparent Polymeric Material Exposed to Simulated Space Environment

NASA Technical Reports Server (NTRS)

Edwards, David L.; Finckenor, Miria M.

1999-01-01

Transparent polymeric materials are being designed and utilized as solar concentrating lenses for spacecraft power and propulsion systems. These polymeric lenses concentrate solar energy onto energy conversion devices such as solar cells and thermal energy systems. The conversion efficiency is directly related to the transmissivity of the polymeric lens. The Environmental Effects Group of the Marshall Space Flight Center's Materials, Processes, and Manufacturing Department exposed a variety of materials to a simulated space environment and evaluated them for an, change in optical transmission. These materials include Lexan(TM), polyethylene terephthalate (PET). several formulations of Tefzel(TM). and Teflon(TM), and silicone DC 93-500. Samples were exposed to a minimum of 1000 Equivalent Sun Hours (ESH) of near-UV radiation (250 - 400 nm wavelength). Data will be presented on materials exposed to charged particle radiation equivalent to a five-year dose in geosynchronous orbit. These exposures were performed in MSFC's Combined Environmental Effects Test Chamber, a unique facility with the capability to expose materials simultaneously or sequentially to protons, low-energy electrons, high-energy electrons, near UV radiation and vacuum UV radiation.Prolonged exposure to the space environment will decrease the polymer film's transmission and thus reduce the conversion efficiency. A method was developed to normalize the transmission loss and thus rank the materials according to their tolerance to space environmental exposure. Spectral results and the material ranking according to transmission loss are presented.

High-Heat-Flux Cyclic Durability of Thermal and Environmental Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Ghosn, Louis L.; Miller, Robert A.

2007-01-01

Advanced ceramic thermal and environmental barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to protect the engine components and further raise engine temperatures. For the supersonic vehicles currently envisioned in the NASA fundamental aeronautics program, advanced gas turbine engines will be used to provide high power density thrust during the extended supersonic flight of the aircraft, while meeting stringent low emission requirements. Advanced ceramic coating systems are critical to the performance, life and durability of the hot-section components of the engine systems. In this work, the laser and burner rig based high-heat-flux testing approaches were developed to investigate the coating cyclic response and failure mechanisms under simulated supersonic long-duration cruise mission. The accelerated coating cracking and delamination mechanism under the engine high-heat-flux, and extended supersonic cruise time conditions will be addressed. A coating life prediction framework may be realized by examining the crack initiation and propagation in conjunction with environmental degradation under high-heat-flux test conditions.

Creep, Fatigue and Fracture Behavior of Environmental Barrier Coating and SiC-SiC Ceramic Matrix Composite Systems: The Role of Environment Effects

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Ghosn, Louis J.

2015-01-01

Advanced environmental barrier coating (EBC) systems for low emission SiCSiC CMC combustors and turbine airfoils have been developed to meet next generation engine emission and performance goals. This presentation will highlight the developments of NASAs current EBC system technologies for SiC-SiC ceramic matrix composite combustors and turbine airfoils, their performance evaluation and modeling progress towards improving the engine SiCSiC component temperature capability and long-term durability. Our emphasis has also been placed on the fundamental aspects of the EBC-CMC creep and fatigue behaviors, and their interactions with turbine engine oxidizing and moisture environments. The EBC-CMC environmental degradation and failure modes, under various simulated engine testing environments, in particular involving high heat flux, high pressure, high velocity combustion conditions, will be discussed aiming at quantifying the protective coating functions, performance and durability, and in conjunction with damage mechanics and fracture mechanics approaches.

Self-healing of the superhydrophobicity by ironing for the abrasion durable superhydrophobic cotton fabrics

PubMed Central

Wu, Jingxia; Li, Jingye; Deng, Bo; Jiang, Haiqing; Wang, Ziqiang; Yu, Ming; Li, Linfan; Xing, Chenyang; Li, Yongjin

2013-01-01

Self-healing of the superhydrophobic cotton fabric (SCF) obtained by the radiation-induced graft polymerization of lauryl methacrylate (LMA) and n-hexyl methacrylate (HMA), can be achieved by ironing. Through the steam ironing process, the superhydrophobicity of the SCFs will be regenerated even after the yarns are ruptured during the abrasion test under a load pressure of 44.8 kPa. SCFs made from LMA grafted cotton fabric can ultimately withstand at least 24,000 cycles of abrasion with periodic steam ironing. The FT-IR microscope results show that the migration of the polymethacrylates graft chains from the interior to the surface is responsible for the self-healing effect. PMID:24135813

Electrically Conductive TPU Nanofibrous Composite with High Stretchability for Flexible Strain Sensor

NASA Astrophysics Data System (ADS)

Tong, Lu; Wang, Xiao-Xiong; He, Xiao-Xiao; Nie, Guang-Di; Zhang, Jun; Zhang, Bin; Guo, Wen-Zhe; Long, Yun-Ze

2018-03-01

Highly stretchable and electrically conductive thermoplastic polyurethane (TPU) nanofibrous composite based on electrospinning for flexible strain sensor and stretchable conductor has been fabricated via in situ polymerization of polyaniline (PANI) on TPU nanofibrous membrane. The PANI/TPU membrane-based sensor could detect a strain from 0 to 160% with fast response and excellent stability. Meanwhile, the TPU composite has good stability and durability. Besides, the composite could be adapted to various non-flat working environments and could maintain opportune conductivity at different operating temperatures. This work provides an easy operating and low-cost method to fabricate highly stretchable and electrically conductive nanofibrous membrane, which could be applied to detect quick and tiny human actions.

Dye Foils With Increased Durability For Passive Q-Switching In A 1064 Nm Laser.

NASA Astrophysics Data System (ADS)

Mierczyk, Z.; Kwasny, M.; Czeszko, J.

1987-10-01

The results of spectral (IR, UV-VIS, H NMR) , gel permeation chromatography and differential thermal analysis investigations of structures of dye foils consisting of bis-(4-dimethyl-amino-dithio-benzil)-nickel dye suspended in polymethylmethacrylate matrix, to be used for passive Q-switching in a 1064 nm laser, are reported. Results of experimental measurements and of numerical calculations of thermal and generating properties, and of the endurance of passive foil type Q-switches in the resona-tor of YAG:Nd3+ laser are also presented. Optimization of polymerization conditions has enabled the production of dye foils with high thermal and photochemical resistance, which give stable operation of a giant pulsed laser.

Durable anti-fogging effect and adhesion improvement on polymer surfaces

NASA Astrophysics Data System (ADS)

Moser, E. M.; Gilliéron, D.; Henrion, G.

2010-01-01

The hydrophobic properties of polymeric surfaces may cause fogging in transparent packaging and poor adhesion to printing colours and coatings. Novel plasma processes for durable functionalization of polypropylene and polyethylene terephthalate substrates were developed and analysed using optical emission spectroscopy. A worm-like nano pattern was created on the polypropylene surface prior to the deposition of thin polar plasma polymerised layers. For both substrates, highly polar surfaces exhibiting a surface tension of up to 69 mN/m and a water contact angle of about 10° were produced - providing the anti-fogging effect. The deposition of thin plasma polymerised layers protects the increased surface areas and enables to tailoring the surface energy of the substrate in a wide range. Wetting characteristics were determined by dynamic contact angle measurements. Investigations of the chemical composition of several layers using X-ray photoelectron spectroscopy and FT-infrared spectroscopy were correlated with functional testing. The surface topography was investigated using atomic force microscopy. The weldability and peeling-off characteristics of the plasma treated polymer films could be adjusted by varying the process parameters. Global and specific migration analyses were undertaken in order to ensure the manufacturing of plasma treated polymer surfaces for direct food contact purposes.

Strength and Durability Performance of Alkali-Activated Rice Husk Ash Geopolymer Mortar

PubMed Central

Kim, Yun Yong; Lee, Byung-Jae; Saraswathy, Velu

2014-01-01

This paper describes the experimental investigation carried out to develop the geopolymer concrete based on alkali-activated rice husk ash (RHA) by sodium hydroxide with sodium silicate. Effect on method of curing and concentration of NaOH on compressive strength as well as the optimum mix proportion of geopolymer mortar was investigated. It is possible to achieve compressive strengths of 31 N/mm2 and 45 N/mm2, respectively for the 10 M alkali-activated geopolymer mortar after 7 and 28 days of casting when cured for 24 hours at 60°C. Results indicated that the increase in curing period and concentration of alkali activator increased the compressive strength. Durability studies were carried out in acid and sulfate media such as H2SO4, HCl, Na2SO4, and MgSO4 environments and found that geopolymer concrete showed very less weight loss when compared to steam-cured mortar specimens. In addition, fluorescent optical microscopy and X-ray diffraction (XRD) studies have shown the formation of new peaks and enhanced the polymerization reaction which is responsible for strength development and hence RHA has great potential as a substitute for ordinary Portland cement concrete. PMID:25506063

Preparation and properties of electro-conductive fabrics based on polypyrrole: covalent vs. non-covalent attachment

NASA Astrophysics Data System (ADS)

David, N. C.; Anavi, D.; Milanovich, M.; Popowski, Y.; Frid, L.; Amir, E.

2017-10-01

Electro-conductive fabrics were prepared via in situ oxidative polymerization of pyrrole (Py) in the presence of unmodified and chemically modified cotton fabrics. Chemical modification of cotton fabric was achieved by covalent attachment of a bifunctional linker molecule to the surface of the fabric, followed by incorporation of a monomer unit onto the linker. The fabrics were characterized using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron spectroscopy, and thermal analysis. Furthermore, the effect of Py concentration on the degree of polypyrrole (PPy) grafting, surface morphology, electrical resistivity, and laundering durability were studied for both types of cotton fabrics. Reductions of several orders of magnitude in surface and volume electrical resistivities were observed for both non-covalently and covalently linked cotton-PPy systems, whereas the effect of covalent pre-treatment of the fabric was stronger at low Py concentration. On the other hand, at higher monomer concentration, the electrical properties and laundering durability of the fabrics we comparable for both unmodified and chemically pre-treated cotton fabrics, indicating that only a small fraction of PPy chains were chemically grafted onto the fabric surface with the majority of the polymer being connected to the fabric through hydrogen bonds.

Bacillus megaterium mediated mineralization of calcium carbonate as biogenic surface treatment of green building materials.

PubMed

Dhami, Navdeep Kaur; Reddy, M Sudhakara; Mukherjee, Abhijit

2013-12-01

Microbially induced calcium carbonate precipitation is a biomineralization process that has various applications in remediation and restoration of range of building materials. In the present study, calcifying bacteria, Bacillus megaterium SS3 isolated from calcareous soil was applied as biosealant to enhance the durability of low energy, green building materials (soil-cement blocks). This bacterial isolate produced high amounts of urease, carbonic anhydrase, extra polymeric substances and biofilm. The calcium carbonate polymorphs produced by B. megaterium SS3 were analyzed by scanning electron microscopy, confocal laser scanning microscopy, X-ray diffraction and Fourier transmission infra red spectroscopy. These results suggested that calcite is the most predominant carbonate formed by this bacteria followed by vaterite. Application of B. megaterium SS3 as biogenic surface treatment led to 40 % decrease in water absorption, 31 % decrease in porosity and 18 % increase in compressive strength of low energy building materials. From the present investigation, it is clear that surface treatment of building materials by B. megaterium SS3 is very effective and eco friendly way of biodeposition of coherent carbonates that enhances the durability of building materials.

Electrochemical performance and durability of carbon supported Pt catalyst in contact with aqueous and polymeric proton conductors.

PubMed

Andersen, Shuang Ma; Skou, Eivind

2014-10-08

Significant differences in catalyst performance and durability are often observed between the use of a liquid electrolyte (e.g., sulfuric acid), and a solid polymer electrolyte (e.g., Nafion). To understand this phenomenon, we studied the electrochemical behavior of a commercially available carbon supported platinum catalyst in four different electrode structures: catalyst powder (CP), catalyst ionomer electrode (CIE), half membrane electrode assembly (HMEA), and full membrane electrode assembly (FMEA) in both ex situ and in situ experiments under a simulated start/stop cycle. We found that the catalyst performance and stability are very much influenced by the presence of the Nafion ionomers. The proton conducting phase provided by the ionomer and the self-assembled electrode structure render the catalysts a higher utilization and better stability. This is probably due to an enhanced dispersion, an improved proton-catalyst interface, the restriction of catalyst particle aggregation, and the improved stability of the ionomer phase especially after the lamination. Therefore, an innovative electrode HMEA design for ex-situ catalyst characterization is proposed. The electrode structure is identical to the one used in a real fuel cell, where the protons transport takes place solely through solid state proton conducting phase.

Preparation and Characterization of Space Durable Polymer Nanocomposite Films from Functionalized Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Delozier, D. M.; Connell, J. W.; Smith, J. G.; Watson, K. A.

2003-01-01

Low color, flexible, space durable polyimide films with inherent, robust electrical conductivity have been under investigation as part of a continuing materials development activity for future NASA space missions involving Gossamer structures. Electrical conductivity is needed in these films to dissipate electrostatic charge build-up that occurs due to the orbital environment. One method of imparting conductivity is through the use of single walled carbon nanotubes (SWNTs). However, the incompatibility and insolubility of the SWNTs severely hampers their dispersion in polymeric matrices. In an attempt to improve their dispersability, SWNTs were functionalized by the reaction with an alkyl hydrazone. After this functionalization, the SWNTs were soluble in select solvents and dispersed more readily in the polymer matrix. The functionalized SWNTs were characterized by Raman spectroscopy and thermogravimetric analysis (TGA). The functionalized nanotubes were dispersed in the bulk of the films using a solution technique. The functionalized nanotubes were also applied to the surface of polyimide films using a spray coating technique. The resultant polyimide nanocomposite films were evaluated for nanotube dispersion, electrical conductivity, mechanical, and optical properties and compared with previously prepared polyimide-SWNT samples to assess the effects of SWNT functionalization.

Preliminary Assessment of Potential Habitat Composites' Durability when Exposed to a Long-Term Radiation Environment and Micrometeoroid Impacts

NASA Technical Reports Server (NTRS)

Rojdev, Kristina; Graves, Russell; Golden, John; Atwell, William; O'Rouke, Mary Jane; Hill, Charles; Alred, John

2011-01-01

NASA's exploration goals include extending human presence beyond low earth orbit (LEO). As a result, habitation for crew is a critical requirement for meeting this goal. However, habitats are very large structures that contain a multitude of subsystems to sustain human life over long-durations in space, and one of the key challenges has been keeping weight to a minimum in order to reduce costs. Thus, light-weight and multifunctional structural materials are of great interest for habitation. NASA has started studying polymeric composite materials as potential lightweight and multifunctional structural materials for use in long-duration spaceflight. However, little is known about the survivability of these materials when exposed to the space environment outside of LEO for long durations. Thus, a study has been undertaken to investigate the durability of composite materials when exposed to long-duration radiation. Furthermore, as an addition to the primary study, a secondary preliminary investigation has been started on the micrometeoroid and orbital debris (MMOD) susceptibility of these materials after radiation exposure. The combined effects of radiation and MMOD impacts are the focus of this paper.

Sol-gel applications for ceramic membrane preparation

NASA Astrophysics Data System (ADS)

Erdem, I.

2017-02-01

Ceramic membranes possessing superior properties compared to polymeric membranes are more durable under severe working conditions and therefore their service life is longer. The ceramic membranes are composed of some layers. The support is the layer composed of coarser ceramic structure and responsible for mechanical durability under filtration pressure and it is prepared by consolidation of ceramic powders. The top layer is composed of a finer ceramic micro-structure mainly responsible for the separation of components present in the fluid to be filtered and sol-gel method is a versatile tool to prepare such a tailor-made ceramic filtration structure with finer pores. Depending on the type of filtration (e.g. micro-filtration, ultra-filtration, nano-filtration) aiming separation of components with different sizes, sols with different particulate sizes should be prepared and consolidated with varying precursors and preparation conditions. The coating of sol on the support layer and heat treatment application to have a stable ceramic micro-structure are also important steps determining the final properties of the top layer. Sol-gel method with various controllable parameters (e.g. precursor type, sol formation kinetics, heat treatment conditions) is a practical tool for the preparation of top layers of ceramic composite membranes with desired physicochemical properties.

Waste Isolation Pilot Plant Salt Decontamination Testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demmer, Ricky Lynn; Reese, Stephen Joseph

2015-03-01

On February 14, 2014, americium and plutonium contamination was released in the Waste Isolation Pilot Plant (WIPP) salt caverns. Several practical, easily deployable methods of decontaminating WIPP salt, using a surrogate contaminant and americium (241Am), were developed and tested. The effectiveness of the methods is evaluated qualitatively, and to the extent practical, quantitatively. Of the methods tested (dry brushing, vacuum cleaning, water washing, mechanical grinding, strippable coatings, and fixative barriers), the most practical seems to be water washing. Effectiveness is very high, and water washing is easy and rapid to deploy. The amount of wastewater produced (~2 L/m2) would bemore » substantial and may not be easy to manage, but the method is the clear winner from a usability perspective. Removable surface contamination levels (smear results) from water washed coupons found no residual removable contamination. Thus, whatever contamination is left is likely adhered to (or trapped within) the salt. The other option that shows promise is the use of a fixative barrier. Bartlett Nuclear, Inc.’s Polymeric Barrier System proved the most durable of the coatings tested. The coatings were not tested for contaminant entrapment, only for coating integrity and durability.« less

Strength and durability performance of alkali-activated rice husk ash geopolymer mortar.

PubMed

Kim, Yun Yong; Lee, Byung-Jae; Saraswathy, Velu; Kwon, Seung-Jun

2014-01-01

This paper describes the experimental investigation carried out to develop the geopolymer concrete based on alkali-activated rice husk ash (RHA) by sodium hydroxide with sodium silicate. Effect on method of curing and concentration of NaOH on compressive strength as well as the optimum mix proportion of geopolymer mortar was investigated. It is possible to achieve compressive strengths of 31 N/mm(2) and 45 N/mm(2), respectively for the 10 M alkali-activated geopolymer mortar after 7 and 28 days of casting when cured for 24 hours at 60°C. Results indicated that the increase in curing period and concentration of alkali activator increased the compressive strength. Durability studies were carried out in acid and sulfate media such as H2SO4, HCl, Na2SO4, and MgSO4 environments and found that geopolymer concrete showed very less weight loss when compared to steam-cured mortar specimens. In addition, fluorescent optical microscopy and X-ray diffraction (XRD) studies have shown the formation of new peaks and enhanced the polymerization reaction which is responsible for strength development and hence RHA has great potential as a substitute for ordinary Portland cement concrete.

Degradation mechanisms and accelerated testing in PEM fuel cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borup, Rodney L; Mukundan, Rangachary

2010-01-01

The durability of PEM fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. Although there has been recent progress in improving durability, further improvements are needed to meet the commercialization targets. Past improvements have largely been made possible because of the fundamental understanding of the underlying degradation mechanisms. By investigating component and cell degradation modes; defining the fundamental degradation mechanisms of components and component interactions new materials can be designed to improve durability. Various factors have been shown to affect the useful life of PEM fuel cells. Other issues arise frommore » component optimization. Operational conditions (such as impurities in either the fuel and oxidant stream), cell environment, temperature (including subfreezing exposure), pressure, current, voltage, etc.; or transient versus continuous operation, including start-up and shutdown procedures, represent other factors that can affect cell performance and durability. The need for Accelerated Stress Tests (ASTs) can be quickly understood given the target lives for fuel cell systems: 5000 hours ({approx} 7 months) for automotive, and 40,000 hrs ({approx} 4.6 years) for stationary systems. Thus testing methods that enable more rapid screening of individual components to determine their durability characteristics, such as off-line environmental testing, are needed for evaluating new component durability in a reasonable turn-around time. This allows proposed improvements in a component to be evaluated rapidly and independently, subsequently allowing rapid advancement in PEM fuel cell durability. These tests are also crucial to developers in order to make sure that they do not sacrifice durability while making improvements in costs (e.g. lower platinum group metal [PGM] loading) and performance (e.g. thinner membrane or a GDL with better water management properties). To achieve a deeper understanding and improve PEM fuel cell durability LANL is conducting research to better define fuel cell component degradation mechanisms and correlate AST measurements to component in 'real-world' situations.« less

Survey of long-term durability of fiberglass reinforced plastic structures

NASA Technical Reports Server (NTRS)

Lieblein, S.

1981-01-01

Included are fluid containment vessels, marine structures, and aircraft components with up to 19 years of service. Correlations were obtained for the variation of static fatigue strength, cyclic fatigue strength, and residual burst strength for pressure vessels. In addition, data are presented for the effects of moisture on strength retention. Data variations were analyzed, and relationships and implications for testing are discussed. Change in strength properties for complete structures was examined for indications of the effects of environmental conditions such as moisture and outdoor exposure (ultraviolet radiation, weathering) on long term durability.

A critical study of the role of the surface oxide layer in titanium bonding

NASA Technical Reports Server (NTRS)

Dias, S.; Wightman, J. P.

1983-01-01

Scanning electron microscope/X-ray photoelectron spectroscopy (SEM/XPS) analysis of fractured adhesively bonded Ti 6-4 samples is discussed. The text adhesives incuded NR 056X polyimide, polypheylquinoxaline (PPQ), and LARC-13 polyimide. Differentiation between cohesive and interfacial failure was based on the absence of presence of a Ti 2p XPS photopeak. In addition, the surface oxide layer on Ti-(6A1-4V) adherends is characterized and bond strength and durability are addressed. Bond durability in various environmental conditions is discussed.

CMC Research at NASA Glenn in 2017: Recent Progress and Plans

NASA Technical Reports Server (NTRS)

Grady, Joseph E.

2017-01-01

As part of NASA's Aeronautics research mission, Glenn Research Center has developed advanced constituents for 2700F CMC turbine engine applications. In this presentation, fiber and matrix development and characterization for SiCSiC composites will be reviewed and resulting improvements in CMC durability and mechanical properties will be summarized. Progress toward the development and validation of models predicting the effects of the engine environment on durability of CMC and Environmental Barrier Coatings will be summarized and plans for research and collaborations in 2017 will be summarized.

Polymeric carbon nitride for solar hydrogen production.

PubMed

Li, Xiaobo; Masters, Anthony F; Maschmeyer, Thomas

2017-07-04

If solar hydrogen production from water is to be a realistic candidate for industrial hydrogen production, the development of photocatalysts, which avoid the use of expensive and/or toxic elements is highly desirable from a scalability, cost and environmental perspective. Metal-free polymeric carbon nitride is an attractive material that can absorb visible light and produce hydrogen from water. This article reviews recent developments in polymeric carbon nitride as used in photocatalysis and then develops the discussion focusing on the three primary processes of a photocatalytic reaction: light-harvesting, carrier generation/separation/transportation and surface reactions.

ESEM analysis of polymeric film in EVA-modified cement paste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silva, D.A.; Monteiro, P.J.M.

2005-10-01

Portland cement pastes modified by 20% weight (polymer/cement ratio) of poly(ethylene-co-vinyl acetate) (EVA) were prepared, cured, and immersed in water for 11 days. The effects of water saturation and drying on the EVA polymeric film formed in cement pastes were observed using environmental scanning electron microscopy (ESEM). This technique allowed the imaging of the EVA film even in saturated samples. The decrease of the relative humidity inside the ESEM chamber did not cause any visual modification of the polymeric film during its drying.

Relationship between Leakage Current and Pollution Deposits on the Surface of Polymeric Insulator

NASA Astrophysics Data System (ADS)

Miyake, Takuma; Seo, Yuya; Sakoda, Tatsuya; Otsubo, Masahisa

Application of polymeric materials used for housing insulators is considered. However, because polymeric insulator is organic matter, the aged deterioration is anxious. The lifetime of polymeric insulator is influenced by environmental conditions such as ultraviolet, acid rain, and polluted deposits. A change of the surface condition of polymeric material causes the dry band arc discharge and the discharge may lower the insulation strength. To investigate the relationship between insoluble pollution and occurrence of dry band arc discharge, we performed a salt-fog test with ethylene vinyl acetate (EVA) samples. The results showed that the heavy erosion caused by frequent dry band arc discharges occurred even in the case of a light polluted condition. Additionally, a very characteristic increase tendency in leakage current with a period of about 5 h was observed during the mist period.

Technical Testing of the Wristwatch Size Automatic Physiological and Environmental Monitor (WAPEM): Laboratory and Outdoor Evaluations of Environmental Sensors Performance

DTIC Science & Technology

2004-03-01

relative humidity (RH), ambient temperature (Ta), solar radiation (SR), and human activity in a small, water- resistant, durable enclosure. It is fitted...temperature, SR, and human activity . The activity channel is designed to function for sleep scoring (ZGM), as well as monitoring daytime activity with the

Investigation of Expandable Polymeric Microspheres for Packaging Applications

DTIC Science & Technology

2012-06-06

FILMS COST REDUCTION OLEFIN POLYMERS COSTS PACKAGING MICROSPHERES WASTE DISPOSAL WEIGHT...MANAGEMENT THERMAL INSULATION DENSITY SOLID WASTES ENVIRONMENTAL IMPACT THERMOPLASTIC POLYMERS POLYMERS ...research. The purpose was to provide information on the incorporation of hollow, expandable  polymeric microspheres  into  thermoplastic   polymers   to

High performance and durability of order-structured cathode catalyst layer based on TiO2@PANI core-shell nanowire arrays

NASA Astrophysics Data System (ADS)

Chen, Ming; Wang, Meng; Yang, Zhaoyi; Wang, Xindong

2017-06-01

In this paper, an order-structured cathode catalyst layer consisting of Pt-TiO2@PANI core-shell nanowire arrays that in situ grown on commercial gas diffusion layer (GDL) are prepared and applied to membrane electrode assembly (MEA) of proton exchange membrane fuel cell (PEMFC). In order to prepare the TiO2@PANI core-shell nanowire arrays with suitable porosity and prominent conductivity, the morphologies of the TiO2 nanoarray and electrochemical polymerization process of aniline are schematically investigated. The MEA with order-structured cathode catalyst layer is assembled in the single cell to evaluate the electrochemical performance and durability of PEMFC. As a result, the PEMFC with order-structured cathode catalyst layer shows higher peak power density (773.54 mW cm-2) than conventional PEMFC (699.30 mW cm-2). Electrochemically active surface area (ECSA) and charge transfer impedance (Rct) are measured before and after accelerated degradation test (ADT), and the corresponding experimental results indicate the novel cathode structure exhibits a better stability with respect to conventional cathode. The enhanced electrochemical performance and durability toward PEMFC can be ascribed to the order-structured cathode nanoarray structure with high specific surface area increases the utilization of catalyst and reduces the tortuosity of transport pathways, and the synergistic effect between TiO2@PANI support and Pt nanoparticles promotes the high efficiency of electrochemical reaction and improves the stability of catalyst. This research provides a facile and controllable method to prepare order-structured membrane electrode with lower Pt loading for PEMFC in the future.

Environmental durability of graphite.

DOT National Transportation Integrated Search

2002-01-01

The increasing acceptance and incorporation of fiber-reinforced polymer matrix composites (PMCs) as engineering construction materials have led many to look to the infrastructure as an application for these versatile materials. One such system is pul...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

Oberlin Colleges Adam Joseph Lewis Center for Environmental Studies is a high-performance building featuring an expansive photovoltaic system and a closed-loop groundwater heat pump system. Designers incorporated energy-efficient components and materials that are local, non-toxic, and durable.

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Oberlin College's Adam Joseph Lewis Center for Environmental Studies is a high-performance building featuring an expansive photovoltaic system and a closed-loop groundwater heat pump system. Designers incorporated energy-efficient components and materials that are local, non-toxic, and durable.

Fabrication of superhydrophobic cotton fabrics using crosslinking polymerization method

NASA Astrophysics Data System (ADS)

Jiang, Bin; Chen, Zhenxing; Sun, Yongli; Yang, Huawei; Zhang, Hongjie; Dou, Haozhen; Zhang, Luhong

2018-05-01

With the aim of removing and recycling oil and organic solvent from water, a facile and low-cost crosslinking polymerization method was first applied on surface modification of cotton fabrics for water/oil separation. Micro-nano hierarchical rough structure was constructed by triethylenetetramine (TETA) and trimesoyl chloride (TMC) that formed a polymeric layer on the surface of the fabric and anchored Al2O3 nanoparticles firmly between the fabric surface and the polymer layer. Superhydrophobic property was further obtained through self-assembly grafting of hydrophobic groups on the rough surface. The as-prepared cotton fabric exhibited superoleophilicity in atmosphere and superhydrophobicity both in atmosphere and under oil with the water contact angle of 153° and 152° respectively. Water/oil separation test showed that the as-prepared cotton fabric can handle with various oil-water mixtures with a high separation efficiency over 99%. More importantly, the separation efficiency remained above 98% over 20 cycles of reusing without losing its superhydrophobicity which demonstrated excellent reusability in oil/water separation process. Moreover, the as-prepared cotton fabric possessed good contamination resistance ability and self-cleaning property. Simulation washing process test showed the superhydrophobic cotton fabric maintained high value of water contact angle above 150° after 100 times washing, indicating great stability and durability. In summary, this work provides a brand-new way to surface modification of cotton fabric and makes it a promising candidate material for oil/water separation.

Construction of monomer-free, highly crosslinked, water-compatible polymers.

PubMed

Dailing, E A; Lewis, S H; Barros, M D; Stansbury, J W

2014-12-01

Polymeric dental adhesives require the formation of densely crosslinked network structures to best ensure mechanical strength and durability in clinical service. Monomeric precursors to these materials typically consist of mixtures of hydrophilic and hydrophobic components that potentially undergo phase separation in the presence of low concentrations of water, which is detrimental to material performance and has motivated significant investigation into formulations that reduce this effect. We have investigated an approach to network formation based on nanogels that are dispersed in inert solvent and directly polymerized into crosslinked polymers. Monomers of various hydrophilic or hydrophobic characteristics were copolymerized into particulate nanogels bearing internal and external polymerizable functionality. Nanogel dispersions were stable at high concentrations in acetone or, with some exceptions, in water and produced networks with a wide range of mechanical properties. Networks formed rapidly upon light activation and reached high conversion with extremely low volumetric shrinkage. Prepolymerizing monomers into reactive nanostructures significantly changes how hydrophobic materials respond to water compared with networks obtained from polymerizations involving free monomer. The modulus of fully hydrated networks formed solely from nanogels was shown to equal or exceed the modulus in the dry state for networks based on nanogels containing a hydrophobic dimethacrylate and hydrophilic monomethacrylate, a result that was not observed in a hydroxyethyl methacrylate (HEMA) homopolymer or in networks formed from nanogels copolymerized with HEMA. These results highlight the unique approach to network development from nanoscale precursors and properties that have direct implications in functional dental materials. © International & American Associations for Dental Research.

Final Report for Project titled High Thermal Conductivity Polymer Composites for Low-Cost Heat Exchangers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thibaud-Erkey, Catherine; Alahyari, Abbas

Heat exchangers (HXs) are critical components in a wide range of heat transfer applications, from HVAC (Heating Ventilation and Cooling) to automobiles to manufacturing plants. They require materials capable of transferring heat at high rates while also minimizing thermal expansion over the usage temperature range. Conventionally, metals are used for applications where effective and efficient heat exchange is required, since many metals exhibit thermal conductivity over 100 W/m K. While metal HXs are constantly being improved, they still have some inherent drawbacks due to their metal construction, in particular corrosion. Polymeric material can offer solution to such durability issues andmore » allow designs that cannot be afforded by metal construction either due to complexity or cost. A major drawback of polymeric material is their low thermal conductivity (0.1-0.5? W/mK) that would lead to large system size. Recent improvements in the area of filled polymers have highlighted the possibility to greatly improve the thermal conductivity of polymeric materials while retaining their inherent manufacturing advantage, and have been applied to heat sink applications. Therefore, the objective of this project was to develop a robust review of materials for the manufacturing of industrial and commercial non-metallic heat exchangers. This review consisted of material identification, literature evaluation, as well as empirical and model characterization, resulting in a database of relevant material properties and characteristics to provide guidance for future heat exchanger development.« less

Biomedical applications of stereoregular poly(vinyl alcohol) micro- and nanoparticles

NASA Astrophysics Data System (ADS)

Lyoo, Won Seok; Kim, Joon Ho; Kim, Sam Soo; Ghim, Han Do

2002-11-01

Syndiotactic poly(vinyl alcohol) (PVA)/poly(vinyl pivalate/vinyl acetate) (P(VPi/VAc)) and atactic PVA/PVAc micro- and nanoparticles with skin/core structure have been prepared by heterogeneous saponification of P(VPi/VAc) and PVAc micro- and nanoparticles. Especially, to prepare P(VPi/VAc) and PVAc microparticles having various particle sizes and uniform particle size distribution, vinyl pivalate (VPi)/vinyl acetate (VAc) and VAc were suspension-polymerized using a low-temperature initiator, 2,2"-azobis(2,4-dimethylvaleronitrile). P(VPi/VAc) particles are promising precursor of stereoregular PVA embolic materials which can be introduced through catheters in the management of gastrointestinal bleeders, arteriovenous malformations, hemangiomas, and traumatic rupture of blood vessels. Monodisperse and/or nearly monodisperse P(VPi/VAc) and PVAc microparticles with various particle diameters were obtained by controlling suspension polymerization conditions. Monodisperse P(VPi/VAc) and PVAc microparticles having various particle sizes were partially saponified in the heterogeneous system. PVA/P(VPi/VAc) and PVA/PVAc microparticles having various tacticity and degree of saponification were produced by controlling various polymerization and saponification conditions. The coating of stereoregular PVA micro- and nanoparticles for drug release experiments was conducted with the strepo-avidin-alkaline phosphatase conjugate in variable conditions of pH value, coating buffer, and reaction temperature. Protein-coated syndiotactic PVA micro- and nanoparticles, which does not crosslinking, were more superior to controllability of drug release, durability, and dimensional stability to water and blood than atactic one.

Monte Carlo Computational Modeling of Atomic Oxygen Interactions

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Stueber, Thomas J.; Miller, Sharon K.; De Groh, Kim K.

2017-01-01

Computational modeling of the erosion of polymers caused by atomic oxygen in low Earth orbit (LEO) is useful for determining areas of concern for spacecraft environment durability. Successful modeling requires that the characteristics of the environment such as atomic oxygen energy distribution, flux, and angular distribution be properly represented in the model. Thus whether the atomic oxygen is arriving normal to or inclined to a surface and whether it arrives in a consistent direction or is sweeping across the surface such as in the case of polymeric solar array blankets is important to determine durability. When atomic oxygen impacts a polymer surface it can react removing a certain volume per incident atom (called the erosion yield), recombine, or be ejected as an active oxygen atom to potentially either react with other polymer atoms or exit into space. Scattered atoms can also have a lower energy as a result of partial or total thermal accommodation. Many solutions to polymer durability in LEO involve protective thin films of metal oxides such as SiO2 to prevent atomic oxygen erosion. Such protective films also have their own interaction characteristics. A Monte Carlo computational model has been developed which takes into account the various types of atomic oxygen arrival and how it reacts with a representative polymer (polyimide Kapton H) and how it reacts at defect sites in an oxide protective coating, such as SiO2 on that polymer. Although this model was initially intended to determine atomic oxygen erosion behavior at defect sites for the International Space Station solar arrays, it has been used to predict atomic oxygen erosion or oxidation behavior on many other spacecraft components including erosion of polymeric joints, durability of solar array blanket box covers, and scattering of atomic oxygen into telescopes and microwave cavities where oxidation of critical component surfaces can take place. The computational model is a two dimensional model which has the capability to tune the interactions of how the atomic oxygen reacts, scatters, or recombines on polymer or nonreactive surfaces. In addition to the specification of atomic oxygen arrival details, a total of 15 atomic oxygen interaction parameters have been identified as necessary to properly simulate observed interactions and resulting polymer erosion that have been observed in LEO. The tuning of the Monte Carlo model has been accomplished by adjusting interaction parameters so the erosion patterns produced by the model match those from several actual LEO space experiments. Surface texturing in LEO can also be predicted by the model. Such comparison of space tests with ground laboratory experiments have enabled confidence in ground laboratory lifetime prediction of protected polymers. Results of Monte Carlo tuning, examples of surface texturing and undercutting erosion prediction, and several examples of how the model can be used to predict other LEO and Mars orbital space results are presented.

Ground-Laboratory to In-Space Atomic Oxygen Correlation for the Polymer Erosion and Contamination Experiment (PEACE) Polymers

NASA Technical Reports Server (NTRS)

Stambler, Arielle H.; Inoshita, Karen E.; Roberts, Lily M.; Barbagallo, Claire E.; deGroh, Kim K.; Banks, Bruce A.

2011-01-01

The Materials International Space Station Experiment 2 (MISSE 2) Polymer Erosion and Contamination Experiment (PEACE) polymers were exposed to the environment of low Earth orbit (LEO) for 3.95 years from 2001 to 2005. There were 41 different PEACE polymers, which were flown on the exterior of the International Space Station (ISS) in order to determine their atomic oxygen erosion yields. In LEO, atomic oxygen is an environmental durability threat, particularly for long duration mission exposures. Although spaceflight experiments, such as the MISSE 2 PEACE experiment, are ideal for determining LEO environmental durability of spacecraft materials, ground-laboratory testing is often relied upon for durability evaluation and prediction. Unfortunately, significant differences exist between LEO atomic oxygen exposure and atomic oxygen exposure in ground-laboratory facilities. These differences include variations in species, energies, thermal exposures and radiation exposures, all of which may result in different reactions and erosion rates. In an effort to improve the accuracy of ground-based durability testing, ground-laboratory to in-space atomic oxygen correlation experiments have been conducted. In these tests, the atomic oxygen erosion yields of the PEACE polymers were determined relative to Kapton H using a radio-frequency (RF) plasma asher (operated on air). The asher erosion yields were compared to the MISSE 2 PEACE erosion yields to determine the correlation between erosion rates in the two environments. This paper provides a summary of the MISSE 2 PEACE experiment; it reviews the specific polymers tested as well as the techniques used to determine erosion yield in the asher, and it provides a correlation between the space and ground laboratory erosion yield values. Using the PEACE polymers asher to in-space erosion yield ratios will allow more accurate in-space materials performance predictions to be made based on plasma asher durability evaluation.

Evaluation of Virginia's first heated bridge.

DOT National Transportation Integrated Search

2000-12-01

This study is a contribution to the Heated Bridge Technology Program established in 1991 under the Intermodal Surface Transportation Efficiency Act. The goal of the program was to find durable and environmentally friendly heated bridge technologies f...

Freeze-thaw durability of composite materials.

DOT National Transportation Integrated Search

1996-01-01

Composite materials, produced from polymer resins and high strength fibers, have the potential to be widely used in construction because of their corrosion resistance and high strength-to-weight ratio, However, such environmental factors as extreme t...

Performance of selected polymeric materials on LDEF

NASA Technical Reports Server (NTRS)

Young, Philip R.; Slemp, Wayne S.; Stein, Bland A.

1993-01-01

The NASA Long Duration Exposure Facility (LDEF) provided a unique environmental exposure of a wide variety of materials for potential advanced spacecraft application. This paper examines the molecular level response of selected polymeric materials which flew onboard this vehicle. Polymers include epolyimide, polysulfone, and polystyrene film and polyimide, polysulfone, and epoxy matrix resin/graphite fiber reinforced composites. Several promising experimental films were also studied. Most specimens received 5.8 years of low Earth orbital (LEO) exposure on LDEF. Several samples received on 10 months of exposure. Chemical characterization techniques included ultraviolet-visible and infrared spectroscopy, thermal analysis, x-ray photoelectron spectroscopy, and selected solution property measurements. Results suggest that many molecular level effects present during the first 10 months of exposure were not present after 5.8 years of exposure for specimens on or near Row 9. Increased AO fluence near the end of the mission likely eroded away much environmentally induced surface phenomena. The objective of this work is to provide fundamental information for use in improving the performance of polymeric materials for LEO application. A secondary objective is to gain an appreciation for the constraints and limitations of results from LDEF polymeric materials experiments.

A model for the enantiomeric enrichment of polypeptides on the primitive earth

NASA Technical Reports Server (NTRS)

Blair, N. E.; Bonner, W. A.

1981-01-01

A potential model is presented for the origin of optical activity in polypeptides on the primitive earth due to enantiomeric enrichment in succeeding polymerization-hydrolysis cycles. The model was developed in experiments with the polymerization of a DL-leucine N-carboxyanhydride mixture with a 31.2% enantiomeric excess of the L isomer with sodium methoxide initiator to yield a polyleucine product which was in turn partially hydrolyzed by acid. The polymerization-hydrolysis was found to produce a net 23.8% increase in the enantiomeric excess of the remaining unhydrolyzed polypeptide (14.2% from the polymerization and 9.6% from the partial hydrolysis). On the basis of these results, it is suggested that a slight excess produced by an appropriate chiral physical process may be enhanced by cycles of stereoselective polymerization and hydrolysis driven by fluctuating wet and dry environmental cycles on the primitive earth.

Synergistic effects of ultraviolet radiation, thermal cycling and atomic oxygen on altered and coated Kapton surfaces

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; Bruckner, Eric J.; Rodriguez, Elvin

1992-01-01

The photovoltaic (PV) power system for Space Station Freedom (SSF) uses solar array blankets which provide structural support for the solar cells and house the electrical interconnections. In the low earth orbital (LEO) environment where SSF will be located, surfaces will be exposed to potentially damaging environmental conditions including solar ultraviolet (UV) radiation, thermal cycling, and atomic oxygen. It is necessary to use ground based tests to determine how these environmental conditions would affect the mass loss and optical properties of candidate SSF blanket materials. Silicone containing, silicone coated, and SiO(x) coated polyimide film materials were exposed to simulated LEO environmental conditions to determine their durability and whether the environmental conditions of UV, thermal cycling and oxygen atoms act synergistically on these materials. A candidate PV blanket material called AOR Kapton, a polysiloxane polyimide cast from a solution mixture, shows an improvement in durability to oxygen atoms erosion after exposure to UV radiation or thermal cycling combined with UV radiation. This may indicate that the environmental conditions react synergistically with this material, and the damage predicted by exposure to atomic oxygen alone is more severe than that which would occur in LEO where atomic oxygen, thermal cycling and UV radiation are present together.

Synergistic effects of ultraviolet radiation, thermal cycling, and atomic oxygen on altered and coated Kapton surfaces

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; Bruckner, Eric J.; Rodriguez, Elvin

1992-01-01

The photovoltaic (PV) power system for Space Station Freedom (SSF) uses solar array blankets which provide structural support for the solar cells and house the electrical interconnections. In the low Earth orbital (LEO) environment where SSF will be located, surfaces will be exposed to potentially damaging environmental conditions including solar ultraviolet (UV) radiation, thermal cycling, and atomic oxygen. It is necessary to use ground based tests to determine how these environmental conditions would affect the mass loss and optical properties of candidate SSF blanket materials. Silicone containing, silicone coated, and SiO(x) coated polyimide film materials were exposed to simulated LEO environmental conditions to determine there durability and whether the environmental conditions of UV, thermal cycling and oxygen atoms act synergistically on these materials. A candidate PV blanket material called AOR Kapton, a polysiloxane polyimide cast from a solution mixture, shows an improvement in durability to oxygen atoms erosion after exposure to UV radiation or thermal cycling combined with UV radiation. This may indicate that the environmental conditions react synergistically with this material, and the damage predicted by exposure to atomic oxygen alone is more severe than that which would occur in LEO where atomic oxygen, thermal cycling and UV radiation are present together.

Calcium-Magnesium-Aluminosilicate (CMAS) Infiltration and Cyclic Degradations of Thermal and Environmental Barrier Coatings in Thermal Gradients

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Smialek, Jim; Miller, Robert A.

2014-01-01

In a continuing effort to develop higher temperature capable turbine thermal barrier and environmental barrier coating systems, Calcium-Magnesium-Aluminosilicate (CMAS) resistance of the advanced coating systems needs to be evaluated and improved. This paper highlights some of NASA past high heat flux testing approaches for turbine thermal and environmental barrier coatings assessments in CMAS environments. One of our current emphases has been focused on the thermal barrier - environmental barrier coating composition and testing developments. The effort has included the CMAS infiltrations in high temperature and high heat flux turbine engine like conditions using advanced laser high heat flux rigs, and subsequently degradation studies in laser heat flux thermal gradient cyclic and isothermal furnace cyclic testing conditions. These heat flux CMAS infiltration and related coating durability testing are essential where appropriate CMAS melting, infiltration and coating-substrate temperature exposure temperature controls can be achieved, thus helping quantify the CMAS-coating interaction and degradation mechanisms. The CMAS work is also playing a critical role in advanced coating developments, by developing laboratory coating durability assessment methodologies in simulated turbine engine conditions and helping establish CMAS test standards in laboratory environments.

Transparent, Weakly Conductive Films for Space Applications

NASA Technical Reports Server (NTRS)

Griffin, John; Morgan, Ashraf; Hambourger, Paul D.

2004-01-01

Electrically insulating spacecraft surfaces are vulnerable to nonuniform charge buildup due to particles emitted by the sun. On Mars, insulating surfaces of exploration vehicles and structures will be affected by dust coatings possibly held in place by triboelectric surface charge. Application of a conductive film may be a solution to the charging problem, but the coating must be highly transparent if used on solar panels, lenses, etc. Sheet resistivity requirements depend on the application and are in the range 10(exp 2) - 10(exp 8) ohms/square. Co-deposited indium tin oxide (ITO) and MgF2 is promising, with high transparency, tailorable electrical properties, and durability to atomic oxygen. Due to ITO's relatively narrow bandgap (approximately 3.5 eV), the film might absorb enough ultraviolet to protect polymeric substrates. Recent work on dual-magnetron-sputtered ITO-MgF2 showed that a variety of polymeric substrates can be coated at room temperature. However, the sheet resistivity is very sensitive to composition, suggestive of a percolation transition. This could be a serious problem for large-scale coating production. We will report on attempts to control film composition by plasma emission monitoring of the ITO and MgF2 guns.

Using polymerization, glass structure, and quasicrystalline theory to produce high level radioactive borosilicate glass remotely: a 20+ year legacy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jantzen, Carol M.

Vitrification is currently the most widely used technology for the treatment of high level radioactive wastes (HLW) throughout the world. Most of the nations that have generated HLW are immobilizing in borosilicate glass. One of the primary reasons that glass has become the most widely used immobilization media is the relative simplicity of the vitrification process, e.g. melt a highly variable waste with some glass forming additives such as SiO 2 and B 2O 3 in the form of a premelted frit and pour the molten mixture into a stainless steel canister. Seal the canister before moisture can enter themore » canister (10’ tall by 2’ in diameter) so the canister does not corrode from the inside out. Glass has also become widely used for HLW is that due to the fact that the short range order (SRO) and medium range order (MRO) found in the structure of glass atomistically bonds the radionuclides and hazardous species in the waste. The SRO and MRO have also been found to govern the melt properties such as viscosity and resistivity of the melt and the crystallization potential and solubility of certain species. Furthermore, the molecular structure of the glass also controls the glass durability, i.e. the contaminant/radionuclide release, by establishing the distribution of ion exchange sites, hydrolysis sites, and the access of water to those sites. The molecular structure is flexible and hence accounts for the flexibility of glass formulations to HLW waste variability. Nuclear waste glasses melt between 1050-1150°C which minimizes the volatility of radioactive components such as 99Tc, 137Cs, and 129I. Nuclear waste glasses have good long term stability including irradiation resistance. Process control models were developed based on the molecular structure of glass, polymerization theory of glass, and quasicrystalline theory of glass crystallization. These models create a glass which is durable, pourable, and processable with 95% accuracy without knowing from batch to batch what the composition of the waste coming out of the storage tanks will be. These models have operated the Savannah River Site Defense Waste Processing Facility (SRS DWPF), which is the world’s largest HLW Joule heated ceramic melter, since 1996. This unique “feed forward” process control, which qualifies the durability, pourability, and processability of the waste plus glass additive mixture before it enters the melter, has enabled ~8000 tons of HLW glass and 4242 canisters to be produced since 1996 with only one melter replacement.« less

Using polymerization, glass structure, and quasicrystalline theory to produce high level radioactive borosilicate glass remotely: a 20+ year legacy

DOE PAGES

Jantzen, Carol M.

2017-03-27

Vitrification is currently the most widely used technology for the treatment of high level radioactive wastes (HLW) throughout the world. Most of the nations that have generated HLW are immobilizing in borosilicate glass. One of the primary reasons that glass has become the most widely used immobilization media is the relative simplicity of the vitrification process, e.g. melt a highly variable waste with some glass forming additives such as SiO 2 and B 2O 3 in the form of a premelted frit and pour the molten mixture into a stainless steel canister. Seal the canister before moisture can enter themore » canister (10’ tall by 2’ in diameter) so the canister does not corrode from the inside out. Glass has also become widely used for HLW is that due to the fact that the short range order (SRO) and medium range order (MRO) found in the structure of glass atomistically bonds the radionuclides and hazardous species in the waste. The SRO and MRO have also been found to govern the melt properties such as viscosity and resistivity of the melt and the crystallization potential and solubility of certain species. Furthermore, the molecular structure of the glass also controls the glass durability, i.e. the contaminant/radionuclide release, by establishing the distribution of ion exchange sites, hydrolysis sites, and the access of water to those sites. The molecular structure is flexible and hence accounts for the flexibility of glass formulations to HLW waste variability. Nuclear waste glasses melt between 1050-1150°C which minimizes the volatility of radioactive components such as 99Tc, 137Cs, and 129I. Nuclear waste glasses have good long term stability including irradiation resistance. Process control models were developed based on the molecular structure of glass, polymerization theory of glass, and quasicrystalline theory of glass crystallization. These models create a glass which is durable, pourable, and processable with 95% accuracy without knowing from batch to batch what the composition of the waste coming out of the storage tanks will be. These models have operated the Savannah River Site Defense Waste Processing Facility (SRS DWPF), which is the world’s largest HLW Joule heated ceramic melter, since 1996. This unique “feed forward” process control, which qualifies the durability, pourability, and processability of the waste plus glass additive mixture before it enters the melter, has enabled ~8000 tons of HLW glass and 4242 canisters to be produced since 1996 with only one melter replacement.« less

Probabilistic durability assessment of concrete structures in marine environments: Reliability and sensitivity analysis

NASA Astrophysics Data System (ADS)

Yu, Bo; Ning, Chao-lie; Li, Bing

2017-03-01

A probabilistic framework for durability assessment of concrete structures in marine environments was proposed in terms of reliability and sensitivity analysis, which takes into account the uncertainties under the environmental, material, structural and executional conditions. A time-dependent probabilistic model of chloride ingress was established first to consider the variations in various governing parameters, such as the chloride concentration, chloride diffusion coefficient, and age factor. Then the Nataf transformation was adopted to transform the non-normal random variables from the original physical space into the independent standard Normal space. After that the durability limit state function and its gradient vector with respect to the original physical parameters were derived analytically, based on which the first-order reliability method was adopted to analyze the time-dependent reliability and parametric sensitivity of concrete structures in marine environments. The accuracy of the proposed method was verified by comparing with the second-order reliability method and the Monte Carlo simulation. Finally, the influences of environmental conditions, material properties, structural parameters and execution conditions on the time-dependent reliability of concrete structures in marine environments were also investigated. The proposed probabilistic framework can be implemented in the decision-making algorithm for the maintenance and repair of deteriorating concrete structures in marine environments.

Simultaneous structural and environmental loading of an ultra-high performance concrete component

DOT National Transportation Integrated Search

2010-07-01

Ultra-high performance concrete (UHPC) is an advanced cementitious composite material which tends to exhibit superior properties such as increased durability, strength, and long-term stability. This experimental investigation focused on the flexural ...

Studies on the corrosion resistance of reinforced steel in concrete with ground granulated blast-furnace slag--An overview.

PubMed

Song, Ha-Won; Saraswathy, Velu

2006-11-16

The partial replacement of clinker, the main constituent of ordinary Portland cement by pozzolanic or latent hydraulic industrial by-products such as ground granulated blast furnace slag (GGBFS), effectively lowers the cost of cement by saving energy in the production process. It also reduces CO2 emissions from the cement plant and offers a low priced solution to the environmental problem of depositing industrial wastes. The utilization of GGBFS as partial replacement of Portland cement takes advantage of economic, technical and environmental benefits of this material. Recently offshore, coastal and marine concrete structures were constructed using GGBFS concrete because high volume of GGBFS can contribute to the reduction of chloride ingress. In this paper, the influence of using GGBFS in reinforced concrete structures from the durability aspects such as chloride ingress and corrosion resistance, long term durability, microstructure and porosity of GGBFS concrete has been reviewed and discussed.

Durability assessment to environmental impact of nano-structured consolidants on Carrara marble by field exposure tests.

PubMed

Bonazza, Alessandra; Vidorni, Giorgia; Natali, Irene; Ciantelli, Chiara; Giosuè, Chiara; Tittarelli, Francesca

2017-01-01

The EU policy of reducing the emissions of combustion generated pollutants entails climate induced deterioration to become more important. Moreover, products applied to preserve outdoor built heritage and their preliminary performance tests often turn out to be improper. In such context, the paper reports the outcomes of the methodology adopted to assess the durability and efficiency of nano-based consolidating products utilized for the conservation of carbonate artworks, performing field exposure tests on Carrara marble model samples in different sites in the framework of the EC Project NANOMATCH. Surface properties and cohesion, extent and penetration of the conservative products and their interactions with marble substrates and environmental conditions are here examined after outdoor exposure for eleven months in four different European cities and compared with the features of undamaged and of untreated damaged specimens undergoing the same exposure settings. Copyright © 2016 Elsevier B.V. All rights reserved.

Cadmium sulfide quantum dots/poly(acrylic acid-co-acrylic amide) composite hydrogel synthesized by gamma irradiation

NASA Astrophysics Data System (ADS)

Yang, Tao; Li, Qing; Wen, Wanxin; Hu, Liang; He, Weiwei; Liu, Hanzhou

2018-04-01

To improve the durability and stability of quantum dots (QDs) in the composite hydrogel, an irradiation induced reduction and polymerization-crosslinking method was reported herein where CdS QDs could be synthesized in situ and fastened to polymer chains due to the coordination forces between amino groups and CdS nanoparticles. The morphology and photoluminescence (PL) property of the composite hydrogel were studied. The result indicated that the CdS QDs with uniform size were dispersed evenly in the composite hydrogel, and the introduced CdS QDs had no obvious effect on the hydrogel structure. With the increases of reagent concentrations, PL intensity of the composite hydrogel was enhanced; however, the emission wavelength had no change.

Greener durable concretes through geopolymerisation of blast furnace slag

NASA Astrophysics Data System (ADS)

Rajamane, N. P.; Nataraja, M. C.; Jeyalakshmi, R.; Nithiyanantham, S.

2015-05-01

The eco-friendliness of concrete is quantified by parameters such as ‘embodied energy’ (EE) and ‘embodied CO2 emission’ (ECO2e), besides duration of designed ‘service life’. It may be noted that ECO2e is also referred as carbon footprint (CF) in the literature. Geopolymer (GP) is an inorganic polymeric gel, a type of amorphous alumino-silicate product, which can be synthesised by polycondensation reactions. The concrete reported in this paper was prepared using industrial wastes in the form of blast furnace slag, fly ash as geopolymeric source materials and sodium silicate and sodium hydroxide as activators. Many mechanical properties such as compressive strength, chloride diffusion, steel corrosion, rapid chloride permeability test and rapid migration test are compared with Portland cement.

Property Evaluation and Damage Evolution of Environmental Barrier Coatings and Environmental Barrier Coated SiC/SiC Ceramic Matrix Composite Sub-Elements

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Halbig, Michael; Jaskowiak, Martha; Hurst, Janet; Bhatt, Ram; Fox, Dennis S.

2014-01-01

This paper describes recent development of environmental barrier coatings on SiC/SiC ceramic matrix composites. The creep and fatigue behavior at aggressive long-term high temperature conditions have been evaluated and highlighted. Thermal conductivity and high thermal gradient cyclic durability of environmental barrier coatings have been evaluated. The damage accumulation and complex stress-strain behavior environmental barrier coatings on SiCSiC ceramic matrix composite turbine airfoil subelements during the thermal cyclic and fatigue testing of have been also reported.

Application of microorganisms in concrete: a promising sustainable strategy to improve concrete durability.

PubMed

Wang, Jianyun; Ersan, Yusuf Cagatay; Boon, Nico; De Belie, Nele

2016-04-01

The beneficial effect of microbially induced carbonate precipitation on building materials has been gradually disclosed in the last decade. After the first applications of on historical stones, promising results were obtained with the respect of improved durability. An extensive study then followed on the application of this environmentally friendly and compatible material on a currently widely used construction material, concrete. This review is focused on the discussion of the impact of the two main applications, bacterial surface treatment and bacteria based crack repair, on concrete durability. Special attention was paid to the choice of suitable bacteria and the metabolic pathway aiming at their functionality in concrete environment. Interactions between bacterial cells and cementitious matrix were also elaborated. Furthermore, recommendations to improve the effectiveness of bacterial treatment are provided. Limitations of current studies, updated applications and future application perspectives are shortly outlined.

Nano-scale hydrogen-bond network improves the durability of greener cements

PubMed Central

Jacobsen, Johan; Rodrigues, Michelle Santos; Telling, Mark T. F.; Beraldo, Antonio Ludovico; Santos, Sérgio Francisco; Aldridge, Laurence P.; Bordallo, Heloisa N.

2013-01-01

More than ever before, the world's increasing need for new infrastructure demands the construction of efficient, sustainable and durable buildings, requiring minimal climate-changing gas-generation in their production. Maintenance-free “greener” building materials made from blended cements have advantages over ordinary Portland cements, as they are cheaper, generate less carbon dioxide and are more durable. The key for the improved performance of blends (which substitute fine amorphous silicates for cement) is related to their resistance to water penetration. The mechanism of this water resistance is of great environmental and economical impact but is not yet understood due to the complexity of the cement's hydration reactions. Using neutron spectroscopy, we studied a blend where cement was replaced by ash from sugar cane residuals originating from agricultural waste. Our findings demonstrate that the development of a distinctive hydrogen bond network at the nano-scale is the key to the performance of these greener materials. PMID:24036676

Efficient Storing Energy Harvested by Triboelectric Nanogenerators Using a Safe and Durable All-Solid-State Sodium-Ion Battery.

PubMed

Hou, Huidan; Xu, Qingkai; Pang, Yaokun; Li, Lei; Wang, Jiulin; Zhang, Chi; Sun, Chunwen

2017-08-01

Storing energy harvested by triboelectric nanogenerators (TENGs) from ambient mechanical motion is still a great challenge for achieving low-cost and environmental benign power sources. Here, an all-solid-state Na-ion battery with safe and durable performance used for efficient storing pulsed energy harvested by the TENG is demonstrated. The solid-state sodium-ion batteries are charged by galvanostatic mode and pulse mode with the TENG, respectively. The all-solid-state sodium-ion battery displays excellent cyclic performance up to 1000 cycles with a capacity retention of about 85% even at a high charge and discharge current density of 48 mA g -1 . When charged by the TENG, an energy conversion efficiency of 62.3% is demonstrated. The integration of TENGs with the safe and durable all-solid-state sodium-ion batteries is potential for providing more stable power output for self-powered systems.

Effect of Sizings on the Durability of High Temperature Polymer Composites

NASA Technical Reports Server (NTRS)

Allred, Ronald E.; Shin, E. Eugene; Inghram, Linda; McCorkle, Linda; Papadopoulos, Demetrios; Wheeler, Donald; Sutter, James K.

2003-01-01

To increase performance and durability of high-temperature composite for potential rocket engine components, it is necessary to optimize wetting and interfacial bonding between high modulus carbon fibers and high-temperature polyimide resins. Sizing commercially supplied on most carbon fiber are not compatible with polyimides. In this study, the chemistry of sizing on two high modulus carbon fiber (M40J and M60J, Tiray) was characterized. A continuous desizling system that uses an environmentally friendly chemical-mechanical process was developed for tow level fiber. Composites were fabricated with fibers containing the manufacturer's sizing, desized, and further treated with a reactive finish. Results of room-temperature tests after thermal aging show that the reactive finish produces a higher strength and more durable interface compared to the manufacturer's sizing. When exposed to moisture blistering tests, however, the butter bonded composite displayed a tendency to delaminate, presumably due to trapping of volatiles.

A Review of the Environmental Degradation, Ecotoxicity, and Bioaccumulation Potential of the Low Molecular Weight Polyether Polyol Substances.

PubMed

Schupp, Thomas; Austin, Tom; Eadsforth, Charles V; Bossuyt, Bart; Shen, Summer M; West, Robert J

"Polyalkylene glycol" is the name given to a broad class of synthetic organic chemicals which are produced by polymerization of one or more alkylene oxide (epoxide) monomers, such as ethylene oxide (EO) and propylene oxide (PO), with various initiator substances which possess amine or alcohol groups. A generalization of this polymerization reaction is illustrated in Fig. 1.

Polymer recycling: potential application of radiation technology

NASA Astrophysics Data System (ADS)

Burillo, Guillermina; Clough, Roger L.; Czvikovszky, Tibor; Guven, Olgun; Le Moel, Alain; Liu, Weiwei; Singh, Ajit; Yang, Jingtian; Zaharescu, Traian

2002-04-01

Management of solid waste is an important problem, which is becoming progressively worse as a byproduct of continuing economic growth and development. Polymeric materials (plastics and rubbers) comprise a steadily increasing proportion of the municipal and industrial waste going into landfill. Development of technologies for reducing polymeric waste, which are acceptable from the environmental standpoint, and which are cost-effective, has proven to be a difficult challenge due to complexities inherent in the reuse of polymers. Establishing optimal processes for the reuse/recycling of polymeric materials thus remains a worldwide challenge as we enter the new century. Due to the ability of ionizing radiation to alter the structure and properties of bulk polymeric materials, and the fact that it is applicable to essentially all polymer types, irradiation holds promise for impacting the polymer waste problem. The three main possibilities for use of radiation in this application are: (1) enhancing the mechanical properties and performance of recovered materials or material blends, principally through crosslinking, or through surface modification of different phases being combined; (2) treatment causing or enhancing the decomposition of polymers, particularly through chain scission, leading to recovery of either low molecular weight mixtures, or powders, for use as chemical feedstocks or additives; (3) production of advanced polymeric materials designed for environmental compatibility. This paper provides an overview of the polymer recycling problem, describes the major technological obstacles to the implementation of recycling technologies, and outlines some of the approaches being taken. A review of radiation-based recycling research is then provided, followed by a discussion of future directions where irradiation may be relevant to the problems currently inhibiting the widespread recycling of polymeric materials.

Mechanism of in situ surface polymerization of gallic acid in an environmental-inspired preparation of carboxylated core-shell magnetite nanoparticles.

PubMed

Tóth, Ildikó Y; Szekeres, Márta; Turcu, Rodica; Sáringer, Szilárd; Illés, Erzsébet; Nesztor, Dániel; Tombácz, Etelka

2014-12-30

Magnetite nanoparticles (MNPs) with biocompatible coatings are good candidates for MRI (magnetic resonance imaging) contrasting, magnetic hyperthermia treatments, and drug delivery systems. The spontaneous surface induced polymerization of dissolved organic matter on environmental mineral particles inspired us to prepare carboxylated core-shell MNPs by using a ubiquitous polyphenolic precursor. Through the adsorption and in situ surface polymerization of gallic acid (GA), a polygallate (PGA) coating is formed on the nanoparticles (PGA@MNP) with possible antioxidant capacity. The present work explores the mechanism of polymerization with the help of potentiometric acid-base titration, dynamic light scattering (for particle size and zeta potential determination), UV-vis (UV-visible light spectroscopy), FTIR-ATR (Fourier-transformed infrared spectroscopy by attenuated total reflection), and XPS (X-ray photoelectron spectroscopy) techniques. We observed the formation of ester and ether linkages between gallate monomers both in solution and in the adsorbed state. Higher polymers were formed in the course of several weeks both on the surface of nanoparticles and in the dispersion medium. The ratio of the absorbances of PGA supernatants at 400 and 600 nm (i.e., the E4/E6 ratio commonly used to characterize the degree of polymerization of humic materials) was determined to be 4.3, similar to that of humic acids. Combined XPS, dynamic light scattering, and FTIR-ATR results revealed that, prior to polymerization, the GA monomers became oxidized to poly(carboxylic acid)s due to ring opening while Fe(3+) ions reduced to Fe(2+). Our published results on the colloidal and chemical stability of PGA@MNPs are referenced thoroughly in the present work. Detailed studies on biocompatibility, antioxidant property, and biomedical applicability of the particles will be published.

Environmental Durability of Adhesively Bonded Joints

DTIC Science & Technology

1997-10-14

REPORT DOCUMENTATION PAGE Form Approved OMB No. 07040188 Public reporting burden for tis collection of information isestimated to average 1 hour per...transmittance and reflectance spectroscopy was performed using Nicolet’s OMNIC software for the set-up, control, and analysis of spectroscopic scans... publications inciudc: JAhIN’. W S. iind Butjkus, L.M., "Considetring E~nvironmental Condjitions ill the Design ()’ Bonded Structures: A Fracture

Space environmental effects on polymeric materials

NASA Technical Reports Server (NTRS)

Kiefer, Richard L.; Orwoll, Robert A.

1988-01-01

Two of the major environmental hazards in the Geosynchronous Earth Orbit (GEO) are energetic charged particles and ultraviolet radiation. The charged particles, electrons and protons, range in energy from 0.1 to 4 MeV and each have a flux of 10 to the 8th sq cm/sec. Over a 30 year lifetime, materials in the GEO will have an absorbed dose from this radiation of 10 to the 10th rads. The ultraviolet radiation comes uninhibited from the sun with an irradiance of 1.4 kw/sq m. Radiation is known to initiate chain sission and crosslinking in polymeric materials, both of which affect their structural properties. The 30-year dose level from the combined radiation in the GEO exceeds the threshold for measurable damage in most polymer systems studied. Of further concern is possible synergistic effects from the simultaneous irradiation with charged particles and ultraviolet radiation. Most studies on radiation effects on polymeric materials use either electrons or ultraviolet radiation alone, or in a sequential combination.

COMPOSITES FROM RECYCLED WOOD AND PLASTICS

EPA Science Inventory

The ultimate goal of this research was to develop technology to convert recycled wood fiber and plastics into durable products that are recyclable and otherwise environmentally friendly. Two processing technologies were used to prepare wood-plastic composites: air-laying and melt...

COMPOSITES FROM RECYCLED WOOD AND PLASTICS

EPA Science Inventory

The ultimate goal of this research was to develop technology to convert recycled wood fiber and plastics into durable products that are recyclable and otherwise environmentally friendly. wo processing technologies were used to prepare wood-plastic composites: air-laying and melt-...

The effect of fly ash on the sulfate resistance of concrete

DOT National Transportation Integrated Search

1989-08-01

The durability of concrete is determined by its ability to endure the physical and environmental surroundings without losing the functional properties and structural integrity of the original design. Concrete containing fly ash can be proportioned to...

Facile preparation of super durable superhydrophobic materials.

PubMed

Wu, Lei; Zhang, Junping; Li, Bucheng; Fan, Ling; Li, Lingxiao; Wang, Aiqin

2014-10-15

The low stability, complicated and expensive fabrication procedures seriously hinder practical applications of superhydrophobic materials. Here we report an extremely simple method for preparing super durable superhydrophobic materials, e.g., textiles and sponges, by dip coating in fluoropolymers (FPs). The morphology, surface chemical composition, mechanical, chemical and environmental stabilities of the superhydrophobic textiles were investigated. The results show how simple the preparation of super durable superhydrophobic textiles can be! The superhydrophobic textiles outperform their natural counterparts and most of the state-of-the-art synthetic superhydrophobic materials in stability. The intensive mechanical abrasion, long time immersion in various liquids and repeated washing have no obvious influence on the superhydrophobicity. Water drops are spherical in shape on the samples and could easily roll off after these harsh stability tests. In addition, this simple dip coating approach is applicable to various synthetic and natural textiles and can be easily scaled up. Furthermore, the results prove that a two-tier roughness is helpful but not essential with regard to the creation of super durable superhydrophobic textiles. The combination of microscale roughness of textiles and materials with very low surface tension is enough to form super durable superhydrophobic textiles. According to the same procedure, superhydrophobic polyurethane sponges can be prepared, which show high oil absorbency, oil/water separation efficiency and stability. Copyright © 2014 Elsevier Inc. All rights reserved.

Predicting the long-term durability of hemp-lime renders in inland and coastal areas using Mediterranean, Tropical and Semi-arid climatic simulations.

PubMed

Arizzi, Anna; Viles, Heather; Martín-Sanchez, Inés; Cultrone, Giuseppe

2016-01-15

Hemp-based composites are eco-friendly building materials as they improve energy efficiency in buildings and entail low waste production and pollutant emissions during their manufacturing process. Nevertheless, the organic nature of hemp enhances the bio-receptivity of the material, with likely negative consequences for its long-term performance in the building. The main purpose of this study was to study the response at macro- and micro-scale of hemp-lime renders subjected to weathering simulations in an environmental cabinet (one year was condensed in twelve days), so as to predict their long-term durability in coastal and inland areas with Mediterranean, Tropical and Semi-arid climates, also in relation with the lime type used. The simulated climatic conditions caused almost unnoticeable mass, volume and colour changes in hemp-lime renders. No efflorescence or physical breakdown was detected in samples subjected to NaCl, because the salt mainly precipitates on the surface of samples and is washed away by the rain. Although there was no visible microbial colonisation, alkaliphilic fungi (mainly Penicillium and Aspergillus) and bacteria (mainly Bacillus and Micrococcus) were isolated in all samples. Microbial growth and diversification were higher under Tropical climate, due to heavier rainfall. The influence of the bacterial activity on the hardening of samples has also been discussed here and related with the formation and stabilisation of vaterite in hemp-lime mixes. This study has demonstrated that hemp-lime renders show good durability towards a wide range of environmental conditions and factors. However, it might be useful to take some specific preventive and maintenance measures to reduce the bio-receptivity of this material, thus ensuring a longer durability on site. Copyright © 2015 Elsevier B.V. All rights reserved.

Prediction of fracture toughness and durability of adhesively bonded composite joints with undesirable bonding conditions

NASA Astrophysics Data System (ADS)

Musaramthota, Vishal

Advanced composite materials have enabled the conventional aircraft structures to reduce weight, improve fuel efficiency and offer superior mechanical properties. In the past, materials such as aluminum, steel or titanium have been used to manufacture aircraft structures for support of heavy loads. Within the last decade or so, demand for advanced composite materials have been emerging that offer significant advantages over the traditional metallic materials. Of particular interest in the recent years, there has been an upsurge in scientific significance in the usage of adhesively bonded composite joints (ABCJ's). ABCJ's negate the introduction of stress risers that are associated with riveting or other classical techniques. In today's aircraft transportation market, there is a push to increase structural efficiency by promoting adhesive bonding to primary joining of aircraft structures. This research is focused on the issues associated with the durability and related failures in bonded composite joints that continue to be a critical hindrance to the universal acceptance of ABCJ's. Of particular interest are the short term strength, contamination and long term durability of ABCJ's. One of the factors that influence bond performance is contamination and in this study the influence of contamination on composite-adhesive bond quality was investigated through the development of a repeatable and scalable surface contamination procedure. Results showed an increase in the contaminant coverage area decreases the overall bond strength significantly. A direct correlation between the contaminant coverage area and the fracture toughness of the bonded joint was established. Another factor that influences bond performance during an aircraft's service life is its long term strength upon exposure to harsh environmental conditions or when subjected to severe mechanical loading. A test procedure was successfully developed in order to evaluate durability of ABCJ's comprising severe environmental conditioning, fatiguing in ambient air and a combination of both. The bonds produced were durable enough to sustain the tests cases mentioned above when conditioned for 8 weeks and did not experience any loss in strength. Specimens that were aged for 80 weeks showed a degradation of 10% in their fracture toughness when compared to their baseline datasets. The effect of various exposure times needs to be further evaluated to establish the relationship of durability that is associated with the fracture toughness of ABCJ's.

Electrochemical Impedance Spectrometer with an Environmental Chamber for Rapid Screening of New Precise Copolymers

DTIC Science & Technology

2017-10-07

polymerization to make linear polyethylenes with carboxylic acid groups at precise intervals along the polymer . Precise acid- containing polymers provide...acid polyethylene and the a polymerized ionic liquids based on cyclopropenium. The instrument is also be used to study polymer segmental dynamics...Advances in batteries, fuel cells, and permselective membranes are materials limited. New acid- and ion-containing polymers must be designed and

Improved performance of Bis-GMA/TEGDMA dental composites by net-like structures formed from SiO2 nanofiber fillers.

PubMed

Wang, Xiaoyan; Cai, Qing; Zhang, Xuehui; Wei, Yan; Xu, Mingming; Yang, Xiaoping; Ma, Qi; Cheng, Yali; Deng, Xuliang

2016-02-01

The major objective of this study was to explore the effects of silicon dioxide (SiO2) nanofibers on the performance of 2, 2-bis-[4-(methacryloxypropoxy)-phenyl]-propane (Bis-GMA)/tri-(ethyleneglycol) dimethacrylate (TEGDMA) dental composites. At first, the mechanical properties of Bis-GMA/TEGDMA (50/50, w/w) resins containing different contents of SiO2 nanofibers were evaluated to identify the appropriate composition to achieve the significant reinforcing effect. Secondly, optimized contents (5 or 10wt.%) of SiO2 nanofibers were mixed into resins together with SiO2 microparticles, which was 60wt.% of the resin. Controls for comparison were Bis-GMA/TEGDMA resins containing only SiO2 microparticles (60wt.%) or with additional SiO2 nanoparticles (5 or 10wt.%). Properties including abrasion, polymerization shrinkage and mechanical properties were evaluated to determine the contribution of SiO2 nanofibers. In comparison with SiO2 nanoparticles, SiO2 nanofibers improved the overall performance of Bis-GMA/TEGDMA composite resins, especially in improving abrasion resistance and decreasing polymerization shrinkage. The explanations were that one-dimensional SiO2 nanofibers were able to shield particular fillers from being abraded off, and able to form a kind of overlapped fibrous network to resist polymerization shrinkage. With these approaches, SiO2 nanofiber-containing Bis-GMA composite resins were envisioned a promising choice to achieve long-term durable restorations in clinical therapies. Copyright © 2015. Published by Elsevier B.V.

Thin metal organic frameworks coatings by cathodic electrodeposition for solid-phase microextraction and analysis of trace exogenous estrogens in milk.

PubMed

Lan, Hangzhen; Pan, Daodong; Sun, Yangying; Guo, Yuxing; Wu, Zhen

2016-09-21

Cathodic electrodeposition (CED) has received great attention in metal-organic frameworks (MOFs) synthesis due to its distinguished properties including simplicity, controllability, mild synthesis conditions, and product continuously. Here, we report the fabrication of thin (Et3NH)2Zn3(BDC)4 (E-MOF-5) film coated solid phase microextraction (SPME) fiber by a one-step in situ cathodic electrodeposition strategy. Several etched stainless steel fibers were placed in parallel in order to achieve simultaneously electrochemical polymerization. The influence of different polymerization parameters Et3NHCl concentration and polymerization time were evaluated. The proposed method requires only 20 min for the preparation of E-MOF-5 coating. The optimum coating showed excellent thermal stability and mechanical durability with a long lifetime of more than 120 repetitions SPME operations, and also exhibited higher extraction selectivity and capacity to four estrogens than commonly-used commercial PDMS coating. The limits of detection for the estrogens were 0.17-0.56 ng mL(-1). Fiber-to-fiber reproducibility (n = 8) was in the respective ranges of 3.5%-6.1% relative standard deviation (RSD) for four estrogens for triplicate measurements at 200 ng mL(-1). Finally, the (E-MOF-5) coated fiber was evaluated for ethinylestradiol (EE2), bisphenol A (BPA), diethylstilbestrol (DES), and hexestrol (HEX) extraction in the spiked milk samples. The extraction performance of this new coating was satisfied enough for repeatable use without obvious decline. Copyright © 2016 Elsevier B.V. All rights reserved.

Tunable poly(methacrylic acid-co-acrylamide) nanoparticles through inverse emulsion polymerization.

PubMed

Zhong, Justin X; Clegg, John R; Ander, Eric W; Peppas, Nicholas A

2018-06-01

Environmentally responsive biomaterials have played key roles in the design of biosensors and drug delivery vehicles. Their physical response to external stimuli, such as temperature or pH, can transduce a signal or trigger the release of a drug. In this work, we designed a robust, highly tunable, pH-responsive nanoscale hydrogel system. We present the design and characterization of poly(methacrylic acid-co-acrylamide) hydrogel nanoparticles, crosslinked with methylenebisacrylamide, through inverse emulsion polymerization. The effects of polymerization parameters (i.e., identities and concentrations of monomer and surfactant) and polymer composition (i.e., weight fraction of ionic and crosslinking monomers) on the nanoparticles' bulk and environmentally responsive properties were determined. We generated uniform, spherical nanoparticles which, through modulation of crosslinking, exhibit a volume swelling of 1.77-4.07, relative to the collapsed state in an acidic environment. We believe our system has potential as a base platform for the targeted, injectable delivery of hydrophilic therapeutics. With equal importance, however, we hope that our systematic analysis of the individual impacts of polymerization and purification conditions on nanoparticle composition, morphology, and performance can be used to expedite the development of alternate hydrophilic nanomaterials for a range of biomedical applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1677-1686, 2018. © 2018 Wiley Periodicals, Inc.

Stimuli-sensitive polymeric micelles as anticancer drug carriers.

PubMed

Na, Kun; Sethuraman, Vijay T; Bae, You Han

2006-11-01

Amphiphilic block copolymers often form core-shell type micelles by self-organization of the blocks in an aqueous medium or under specific experimental conditions. Polymeric micelles constructed from these polymers that contain a segment whose physical or chemical properties respond to small changes in environmental conditions are collectively called 'stimuli-sensitive' micelles. This class of nano-scaled constructs has been investigated as a promising anti-cancer drug carrier because the micelles are able to utilize small environmental changes and modify drug release kinetics, biodistribution and the interactions with tissues and cells. This review summarizes the recent progress in stimuli-sensitive micelles for tumor chemotherapy, particularly for those responding to hyperthermic conditions, tumor pH and endosomal/lysosomal pH.

40 CFR 610.52 - Maintenance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 30 2011-07-01 2011-07-01 false Maintenance. 610.52 Section 610.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY RETROFIT DEVICES Test Procedures and Evaluation Criteria Durability Test Procedures § 610.52 Maintenance. (a...

40 CFR 610.52 - Maintenance.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 30 2014-07-01 2014-07-01 false Maintenance. 610.52 Section 610.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY RETROFIT DEVICES Test Procedures and Evaluation Criteria Durability Test Procedures § 610.52 Maintenance. (a...

40 CFR 610.52 - Maintenance.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 31 2013-07-01 2013-07-01 false Maintenance. 610.52 Section 610.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY RETROFIT DEVICES Test Procedures and Evaluation Criteria Durability Test Procedures § 610.52 Maintenance. (a...

40 CFR 610.52 - Maintenance.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 31 2012-07-01 2012-07-01 false Maintenance. 610.52 Section 610.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY RETROFIT DEVICES Test Procedures and Evaluation Criteria Durability Test Procedures § 610.52 Maintenance. (a...

Polymerization model for hydrogen peroxide initiated synthesis of polypyrrole nanoparticles.

PubMed

Leonavicius, Karolis; Ramanaviciene, Almira; Ramanavicius, Arunas

2011-09-06

A very simple, environmentally friendly, one-step oxidative polymerization route to fabricate polypyrrole (Ppy) nanoparticles of fixed size and morphology was developed and investigated. The herein proposed method is based on the application of sodium dodecyl sulfate and hydrogen peroxide, both easily degradable and cheap materials. The polymerization reaction is performed on 24 h time scale under standard conditions. We monitored a polaronic peak at 465 nm and estimated nanoparticle concentration during various stages of the reaction. Using this data we proposed a mechanism for Ppy nanoparticle formation in accordance with earlier emulsion polymerization mechanisms. Rates of various steps in the polymerization mechanism were accounted for and the resulting particles identified using atomic force microscopy. Application of Ppy nanoparticles prepared by the route presented here seems very promising for biomedical applications where biocompatibility is paramount. In addition, this kind of synthesis could be suitable for the development of solar cells, where very pure and low-cost conducting polymers are required. © 2011 American Chemical Society

Radiation-induced controlled polymerization of acrylic acid by RAFT and RAFT-MADIX methods in protic solvents

NASA Astrophysics Data System (ADS)

Sütekin, S. Duygu; Güven, Olgun

2018-01-01

The kinetic investigation of one-pot synthesis of poly(acrylic acid) (PAA) prepared via gamma radiation induced controlled polymerization was reported. PAA homopolymers were prepared by Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization in the presence of trithiocarbonate-based chain transfer agent (CTA) 2-(Dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) and also by Reversible Addition-Fragmentation/Macromolecular Design by Inter-change of Xanthates (RAFT/MADIX) polymerization in the presence of a xanthate based CTA O-ethyl-S-(1-methoxycarbonyl) ethyl dithiocarbonate (RA1). The polymerizations were performed at room temperature by the virtue of ionizing radiation. Protic solvents were used for the RAFT polymerization of AA considering environmental profits. The linear first-order kinetic plot, close control of molecular weight by the monomer/CTA molar ratio supported that the polymerization proceeds in a living fashion. The linear increase in molecular weight with conversion monitored by Size Exclusion Chromatography (SEC) is another proof of controlling of polymerization. [Monomer]/[RAFT] ratio and conversion was controlled to obtain PAA in the molecular weight range of 6900-35,800 with narrow molecular weight distributions. Reaction kinetics and effect of the amount of RAFT agent were investigated in detail. Between two different types of CTA, trithiocarbonate based DDMAT was found to be more efficient in terms of low dispersity (Đ) and linear first-order kinetic behavior for the radiation induced controlled synthesis of PAA homopolymers.

The development of composite materials for spacecraft precision reflector panels

NASA Technical Reports Server (NTRS)

Tompkins, Stephen S.; Bowles, David E.; Funk, Joan G.; Towell, Timothy W.; Lavoie, J. A.

1990-01-01

One of the critical technology needs for large precision reflectors required for future astrophysics and optical communications is in the area of structural materials. Therefore, a major area of the Precision Segmented Reflector Program at NASA is to develop lightweight composite reflector panels with durable, space environmentally stable materials which maintain both surface figure and required surface accuracy necessary for space telescope applications. Results from the materials research and development program at NASA Langley Research Center are discussed. Advanced materials that meet the reflector panel requirements are identified. Thermal, mechanical and durability properties of candidate materials after exposure to simulated space environments are compared to the baseline material.

Environmental and Mechanical Stability of Environmental Barrier Coated SA Tyrannohex SiC Composites Under Simulated Turbine Engine Environments

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Halbig, Michael Charles; Sing, Mrityunjay

2014-01-01

The environmental stability and thermal gradient cyclic durability performance of SA Tyrannohex composites were investigated for turbine engine component applications. The work has been focused on investigating the combustion rig recession, cyclic thermal stress resistance and thermomechanical low cycle fatigue of uncoated and environmental barrier coated Tyrannohex SiC SA composites in simulated turbine engine combustion water vapor, thermal gradients, and mechanical loading conditions. Flexural strength degradations have been evaluated, and the upper limits of operating temperature conditions for the SA composite material systems are discussed based on the experimental results.

Polymer functionalized nanocomposites for metals removal from water and wastewater: An overview.

PubMed

Lofrano, Giusy; Carotenuto, Maurizio; Libralato, Giovanni; Domingos, Rute F; Markus, Arjen; Dini, Luciana; Gautam, Ravindra Kumar; Baldantoni, Daniela; Rossi, Marco; Sharma, Sanjay K; Chattopadhyaya, Mahesh Chandra; Giugni, Maurizio; Meric, Sureyya

2016-04-01

Pollution by metal and metalloid ions is one of the most widespread environmental concerns. They are non-biodegradable, and, generally, present high water solubility facilitating their environmental mobilisation interacting with abiotic and biotic components such as adsorption onto natural colloids or even accumulation by living organisms, thus, threatening human health and ecosystems. Therefore, there is a high demand for effective removal treatments of heavy metals, making the application of adsorption materials such as polymer-functionalized nanocomposites (PFNCs), increasingly attractive. PFNCs retain the inherent remarkable surface properties of nanoparticles, while the polymeric support materials provide high stability and processability. These nanoparticle-matrix materials are of great interest for metals and metalloids removal thanks to the functional groups of the polymeric matrixes that provide specific bindings to target pollutants. This review discusses PFNCs synthesis, characterization and performance in adsorption processes as well as the potential environmental risks and perspectives. Copyright © 2016 Elsevier Ltd. All rights reserved.

Metastable Polymeric Nitrogen: The Ultimate Green High-Energy-Density Material

NASA Astrophysics Data System (ADS)

Ciezak, Jennifer

2007-06-01

High-energy-high-density materials offering increased stability, vulnerability, and environmental safety are being aggressively pursued to meet the requirements of the DoD Joint Visions and Future Force. Nearly two decades ago, it was proposed that polymeric nitrogen would exceed all of these requirements and possess nearly five times the energy of any conventional energetic material in use today. The present study details an investigation into nitrogen polymerization using a novel high-pressure approach utilizing sodium azide as the starting material. Due to the weaker bonding structure of the anionic azide chains in comparison to a N-N triple bond, one expects that the azide chains will create single-covalently bonded polymeric networks more easily than diatomic nitrogen. A polymeric form of sodium azide was synthesized at high pressures, but the material was not metastable at ambient conditions, which precluded performance testing. Quantum chemical calculations have indicated stabilization of the polymeric structure at ambient conditions may be possible with the addition of hydrogen. Vibrational spectroscopic characterization suggests that a meta-stable polymeric form of nitrogen has been synthesized under high-pressure using sodium azide/hydrogen as the starting materials. This material remains stable at ambient conditions upwards of two weeks depending on the storage conditions.

40 CFR 610.50 - Test configurations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 31 2013-07-01 2013-07-01 false Test configurations. 610.50 Section 610.50 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY RETROFIT DEVICES Test Procedures and Evaluation Criteria Durability Test Procedures § 610.50 Test...

40 CFR 610.51 - Mileage accumulation procedure.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 31 2013-07-01 2013-07-01 false Mileage accumulation procedure. 610.51 Section 610.51 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY RETROFIT DEVICES Test Procedures and Evaluation Criteria Durability Test Procedures § 610.51...

40 CFR 610.51 - Mileage accumulation procedure.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 30 2011-07-01 2011-07-01 false Mileage accumulation procedure. 610.51 Section 610.51 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY RETROFIT DEVICES Test Procedures and Evaluation Criteria Durability Test Procedures § 610.51...

40 CFR 610.51 - Mileage accumulation procedure.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 31 2012-07-01 2012-07-01 false Mileage accumulation procedure. 610.51 Section 610.51 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY RETROFIT DEVICES Test Procedures and Evaluation Criteria Durability Test Procedures § 610.51...

40 CFR 610.51 - Mileage accumulation procedure.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 30 2014-07-01 2014-07-01 false Mileage accumulation procedure. 610.51 Section 610.51 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY RETROFIT DEVICES Test Procedures and Evaluation Criteria Durability Test Procedures § 610.51...

LIMITED-USE CHEMICAL PROTECTIVE CLOTHING FOR EPA SUPERFUND ACTIVITIES

EPA Science Inventory

Because contractor field personnel complained about the poor durability and fit of limited-use chemical protective clothing (CPC) most commonly used at hazardous waste site operations, the U.S. Environmental Protection Agency (EPA) initiated a study to characterize use of CPC; de...

40 CFR 610.51 - Mileage accumulation procedure.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Mileage accumulation procedure. 610.51 Section 610.51 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY RETROFIT DEVICES Test Procedures and Evaluation Criteria Durability Test Procedures § 610.51...

LIMITED-USE CHEMICAL PROTECTIVE CLOTHING FOR EPA SUPERFUND ACTIVITIES

EPA Science Inventory

Because contractor field personnel complained about the poor durability and fit of limited-use chemical protective clothing (CPC) most commonly used at hazardous waste site operations, the U.S. Environmental Protection Agency (EPA) initiated a study to • characterize use of CPC...

Ionic Liquids as a Medium for Ionic Chain Polymerizations: An Environmentally Responsible Approach to Macromolecular Synthesis with Controlled Architecture

DTIC Science & Technology

2004-09-16

published in non peer-reviewed journals: 1. Gross, SM, Hamilton JL. "Polymer Gels for Use in Lithium Polymer Batteries", Nebraska Academy of Science...a process for the anionic polymerization of styrene and methyl methacrylate in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ...Current polymer electrolyte composites used for these applications typically comprise polyethers with ethylene carbonate solvents containing lithium

Plasma-Sprayed Refractory Oxide Coatings on Silicon-Base Ceramics

NASA Technical Reports Server (NTRS)

Tewari, Surendra

1997-01-01

Silicon-base ceramics are promising candidate materials for high temperature structural applications such as heat exchangers, gas turbines and advanced internal combustion engines. Composites based on these materials are leading candidates for combustor materials for HSCT gas turbine engines. These materials possess a combination of excellent physical and mechanical properties at high temperatures, for example, high strength, high toughness, high thermal shock resistance, high thermal conductivity, light weight and excellent oxidation resistance. However, environmental durability can be significantly reduced in certain conditions such as when molten salts, H2 or water vapor are present. The oxidation resistance of silicon-base materials is provided by SiO2 protective layer. Molten salt reacts with SiO2 and forms a mixture of SiO2 and liquid silicate at temperatures above 800C. Oxygen diffuses more easily through the chemically altered layer, resulting in a catastrophic degradation of the substrate. SiC and Si3N4 are not stable in pure H2 and decompose to silicon and gaseous species such as CH4, SiH, SiH4, N2, and NH3. Water vapor is known to slightly increase the oxidation rate of SiC and Si3N4. Refractory oxides such as alumina, yttria-stabilized zirconia, yttria and mullite (3Al2O3.2SiO2) possess excellent environmental durability in harsh conditions mentioned above. Therefore, refractory oxide coatings on silicon-base ceramics can substantially improve the environmental durability of these materials by acting as a chemical reaction barrier. These oxide coatings can also serve as a thermal barrier. The purpose of this research program has been to develop refractory oxide chemical/thermal barrier coatings on silicon-base ceramics to provide extended temperature range and lifetime to these materials in harsh environments.

Prédiction du comportement à long terme des matériaux polymères

NASA Astrophysics Data System (ADS)

Lemaire, J.

1998-06-01

Most of the world activity on research, development and control of polymer durability is still based on empirical techniques developed in the early ages of polymer uses. Those techniques should be critically analysed considering the state of the art in the fundamental understanding of these complex phenomena. A more rational approach is described, especially to predict the lifetime of polymeric materials in environmental conditions. That approach is based on the recognition of the chemical evolution mechanisms. Les activités de recherche, développement et contrôle de durabilité des matériaux polymères sont encore, pour une part très importante, basées sur l'emploi de techniques empiriques dont les principes ont été énoncés dès le début de l'exploitation de ces matériaux. Une analyse critique de ces méthodes s'impose aujourd'hui en tenant compte de l'avancement des connaissances. Une approche plus rationnelle est décrite, approche basée sur la reconnaissance des mécanismes d'évolution chimique. A titre d'exemple, le mécanisme d'évolution du PVC sous contraintes conjuguées de l'UV, de la chaleur et de l'oxygène, est décrit. Des études récentes de photooxydation de polymères conducteurs au sein de polyéthylène sont également succinctement rapportées.

The role of the Long Duration Exposure Facility in the development of space systems

NASA Technical Reports Server (NTRS)

Little, Sally A.

1992-01-01

The Long Duration Exposure Facility (LDEF) presents the international, aerospace community with an unprecedented opportunity to examine the synergistic, long term, space environmental effects on systems and materials. The analysis of the data within appropriate environmental contexts is essential to the overall process of advancing the understanding of space environmental effects needed for the continuing development of strategies to improve the reliability and durability of space systems and to effectively deal with the future challenges that new space initiatives will likely present.

78 FR 75268 - Fisheries Off West Coast States; Pacific Coast Groundfish Fishery; Trawl Rationalization Program...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-11

... toward environmental conservation and economic sustainability before cost recovery. NMFS should... fleet's flexibility and economic efficiency will enhance the trawl rationalization program's durability... before economic benefits have been adequately realized and while fishermen are struggling to pay...

Recent Developments in the Environmental Durability of Sic/sic Composites

NASA Technical Reports Server (NTRS)

Ogbuji, Linus U. J. T.

2002-01-01

Two types of pest behavior in SiC/BN/SiC composites are distinguished and illustrated: one intrinsic and progressive, the other extrinsic and catastrophic. Their similarities and differences are presented. Some recent remedies for SiC/BN/SiC pest are discussed.

Hydrophobic Surface Modification of Silk Fabric Using Plasma-Polymerized Hmdso

NASA Astrophysics Data System (ADS)

Rani, K. Vinisha; Chandwani, Nisha; Kikani, Purvi; Nema, S. K.; Sarma, Arun Kumar; Sarma, Bornali

In this work, we study the hydrophobic properties of silk fabrics by deposition of plasma-polymerized (pp) hexamethyldisiloxane (HMDSO) using low-pressure plasma-enhanced chemical vapor deposition. Recently, hydrophobic properties are under active research in textile industry. The effects of coating time and power on the HMDSO-coated silk fabrics are investigated. Water contact angle of pp-HMDSO-coated silk fabric surface is measured as a function of power and coating time. Fabric surface shows an enhancement in hydrophobicity after coating. Attenuated total reflectance-Fourier transform infrared spectroscopy reveals the surface chemistry, and scanning electron microscopy shows the surface morphology of the uncoated and HMDSO-coated fabrics, respectively. In the case of uncoated fabric, water droplet absorbs swiftly, whereas in the case of HMDSO-coated fabric, water droplet remains on the fabric surface with a maximum contact angle of 140∘. The HMDSO-deposited silk surface is found to be durable after detergent washing. Common stains such as ink, tea, milk, turmeric and orange juice are tested on the surface of both fabrics. In HMDSO-coated fabrics, all the stains are bedded like ball droplet. In order to study the self-cleaning property, the fabric is tilted to 45∘ angle; stain droplets easily roll off from the fabric.

Thermal/Mechanical Durability of Polymer-Matrix Composites in Cryogenic Environments

NASA Technical Reports Server (NTRS)

Gates, Thomas S.; Whitley, Karen S.; Grenoble, Ray W.; Bandorawalla, Tozer

2003-01-01

In order to increase the reliability of the next generation of space transportation systems, the mechanical behavior of polymeric-matrix composite (PMC) materials at cryogenic temperatures must be investigated. This paper presents experimental data on the residual mechanical properties of a carbon fiber polymeric composite, IM7/PETI-5 as a function of temperature and aging. Tension modulus and strength were measured at room temperature, -196 C, and -269 C on five different specimens ply lay-ups. Specimens were preconditioned with one set of coupons being isothermally aged for 576 hours at -184 C, in an unloaded state. Another set of corresponding coupons were mounted in constant strain fixtures such that a constant uniaxial strain was applied to the specimens for 576 hours at -184 C. A third set was mechanically cycled in tension at -184 C. The measured properties indicated that temperature, aging, and loading mode can all have significant influence on performance. Moreover, this influence is a strong function of laminate stacking sequence. Thermal-stress calculations based on lamination theory predicted that the transverse tensile ply stresses could be quite high for cryogenic test temperatures. Microscopic examination of the surface morphology showed evidence of degradation along the exposed edges of the material because of aging at cryogenic temperatures. ________________

Electrochemical Study of Polymer and Ceramic-Based Nanocomposite Coatings for Corrosion Protection of Cast Iron Pipeline

PubMed Central

Ammar, Ameen Uddin; Shahid, Muhammad; Ahmed, Muhammad Khitab; Khan, Munawar; Khalid, Amir

2018-01-01

Coating is one of the most effective measures to protect metallic materials from corrosion. Various types of coatings such as metallic, ceramic and polymer coatings have been investigated in a quest to find durable coatings to resist electrochemical decay of metals in industrial applications. Many polymeric composite coatings have proved to be resistant against aggressive environments. Two major applications of ferrous materials are in marine environments and in the oil and gas industry. Knowing the corroding behavior of ferrous-based materials during exposure to these aggressive applications, an effort has been made to protect the material by using polymeric and ceramic-based coatings reinforced with nano materials. Uncoated and coated cast iron pipeline material was investigated during corrosion resistance by employing EIS (electrochemical impedance spectroscopy) and electrochemical DC corrosion testing using the “three electrode system”. Cast iron pipeline samples were coated with Polyvinyl Alcohol/Polyaniline/FLG (Few Layers Graphene) and TiO2/GO (graphene oxide) nanocomposite by dip-coating. The EIS data indicated better capacitance and higher impedance values for coated samples compared with the bare metal, depicting enhanced corrosion resistance against seawater and “produce water” of a crude oil sample from a local oil rig; Tafel scans confirmed a significant decrease in corrosion rate of coated samples. PMID:29495339

Electrochemical Study of Polymer and Ceramic-Based Nanocomposite Coatings for Corrosion Protection of Cast Iron Pipeline.

PubMed

Ammar, Ameen Uddin; Shahid, Muhammad; Ahmed, Muhammad Khitab; Khan, Munawar; Khalid, Amir; Khan, Zulfiqar Ahmad

2018-02-25

Coating is one of the most effective measures to protect metallic materials from corrosion. Various types of coatings such as metallic, ceramic and polymer coatings have been investigated in a quest to find durable coatings to resist electrochemical decay of metals in industrial applications. Many polymeric composite coatings have proved to be resistant against aggressive environments. Two major applications of ferrous materials are in marine environments and in the oil and gas industry. Knowing the corroding behavior of ferrous-based materials during exposure to these aggressive applications, an effort has been made to protect the material by using polymeric and ceramic-based coatings reinforced with nano materials. Uncoated and coated cast iron pipeline material was investigated during corrosion resistance by employing EIS (electrochemical impedance spectroscopy) and electrochemical DC corrosion testing using the "three electrode system". Cast iron pipeline samples were coated with Polyvinyl Alcohol/Polyaniline/FLG (Few Layers Graphene) and TiO₂/GO (graphene oxide) nanocomposite by dip-coating. The EIS data indicated better capacitance and higher impedance values for coated samples compared with the bare metal, depicting enhanced corrosion resistance against seawater and "produce water" of a crude oil sample from a local oil rig; Tafel scans confirmed a significant decrease in corrosion rate of coated samples.

Evaluation of thermal control coatings for use on solar dynamic radiators in low earth orbit

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; Rodriguez, Elvin; Slemp, Wayne S.; Stoyack, Joseph E.

1991-01-01

Thermal control coatings with high thermal emittance and low solar absorptance are needed for Space Station Freedom (SSF) solar dynamic power module radiator (SDR) surfaces for efficient heat rejection. Additionally, these coatings must be durable to low earth orbital (LEO) environmental effects of atomic oxygen, ultraviolet radiation and deep thermal cycles which occur as a result of start-up and shut-down of the solar dynamic power system. Eleven candidate coatings were characterized for their solar absorptance and emittance before and after exposure to ultraviolet (UV) radiation (200 to 400 nm), vacuum UV (VUV) radiation (100 to 200 nm) and atomic oxygen. Results indicated that the most durable and best performing coatings were white paint thermal control coatings Z-93, zinc oxide pigment in potassium silicate binder, and YB-71, zinc orthotitanate pigment in potassium silicate binder. Optical micrographs of these materials exposed to the individual environmental effects of atomic oxygen and vacuum thermal cycling showed that no surface cracking occurred.

The effect of environmental factors on selected mechanical properties of zirconium dioxide

NASA Astrophysics Data System (ADS)

Wirwicki, W.; Andrzejewska, A.; Andryszczyk, M.; Siemianowski, P.

2018-04-01

In many centers around the world, research studies are carried out on the mechanical strength of dental materials and glued joints. A literature review shows the variety of testing techniques related to analyzing the strength and durability of the material itself and the glued joints. In dental ceramics, zirconium dioxide is most often used as a base material, and chemically it consists of 97% ZrO2 and 3% Y2O3. This study was to determine the mechanical properties of zirconium dioxide under different environmental conditions. The material is used for the production of dental crowns and tooth bridges in the CAD/CAM technology. This medium is currently one of the most advanced-generation materials used for prosthetic and implant restorations. They were then subjected to a three-point bending test on the Instron ElektroPlus E3000 durability machine. Storage conditions and time have a positive influence on reducing variation in zirconium resistance for active forces and destructive stresses.

High Temperature Multilayer Environmental Barrier Coatings Deposited Via Plasma Spray-Physical Vapor Deposition

NASA Technical Reports Server (NTRS)

Harder, Bryan James; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

2014-01-01

Si-based ceramic matrix composites (CMCs) require environmental barrier coatings (EBCs) in combustion environments to avoid rapid material loss. Candidate EBC materials have use temperatures only marginally above current technology, but the addition of a columnar oxide topcoat can substantially increase the durability. Plasma Spray-Physical Vapor Deposition (PS-PVD) allows application of these multilayer EBCs in a single process. The PS-PVD technique is a unique method that combines conventional thermal spray and vapor phase methods, allowing for tailoring of thin, dense layers or columnar microstructures by varying deposition conditions. Multilayer coatings were deposited on CMC specimens and assessed for durability under high heat flux and load. Coated samples with surface temperatures ranging from 2400-2700F and 10 ksi loads using the high heat flux laser rigs at NASA Glenn. Coating morphology was characterized in the as-sprayed condition and after thermomechanical loading using electron microscopy and the phase structure was tracked using X-ray diffraction.

Evaluation of thermal control coatings for use on solar dynamic radiators in low Earth orbit

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; Rodriguez, Elvin; Slemp, Wayne S.; Stoyack, Joseph E.

1991-01-01

Thermal control coatings with high thermal emittance and low solar absorptance are needed for Space Station Freedom (SSF) solar dynamic power module radiator (SDR) surfaces for efficient heat rejection. Additionally, these coatings must be durable to low earth orbital (LEO) environmental effects of atomic oxygen, ultraviolet radiation and deep thermal cycles which occur as a result of start-up and shut-down of the solar dynamic power system. Eleven candidate coatings were characterized for their solar absorptance and emittance before and after exposure to ultraviolet (UV) radiation (200 to 400 nm), vacuum UV (VUV) radiation (100 to 200 nm) and atomic oxygen. Results indicated that the most durable and best performing coatings were white paint thermal control coatings Z-93, zinc oxide pigment in potassium silicate binder, and YB-71, zinc orthotitanate pigment in potassium silicate binder. Optical micrographs of these materials exposed to the individual environmental effects of atomic oxygen and vacuum thermal cycling showed that no surface cracking occurred.

Environmentally friendly, one-pot synthesis of folic acid-decorated graphene oxide-based drug delivery system

NASA Astrophysics Data System (ADS)

Lin, Quankui; Huang, Xiaojie; Tang, Junmei; Han, Yuemei; Chen, Hao

2013-12-01

A targeted drug delivery system based on graphene oxide (GO) was produced via one-pot synthesis method, taking advantages of the self-polymerization of the dopamine (DA). The polymerization of dopamine resulted in polydopamine capped GO nanocomposite. Meanwhile, the anti-tumor drug doxorubicin (DOX) can be loaded in the nanocomposite and the tumor cell targeting molecule folic acid (FA) can also been immobilized on the nanocomposite surface simultaneously. The size of the obtained FA-decorated GO-based drug delivery system (DA/GO(DOX)-FA) is about 600 nm. It renders a sustained drug release manner. The cell culture results reveal that the FA-decorated GO-based drug delivery system (DA/GO(DOX)-FA) via one-pot method shows property of targeted killing of cancer cells in vitro. This one-pot method just needs the pH adjusting to induce the self-polymerization of DA, but excludes the fussy chemical grafting process and the organic solvents, which make it an environmentally friendly method to synthesize FA-decorated GO-based drug delivery system.

Presidential Green Chemistry Challenge: 2009 Academic Award

EPA Pesticide Factsheets

Presidential Green Chemistry Challenge 2009 award winner, Professor Krzysztof Matyjaszewski, developed Atom Transfer Radical Polymerization to make polymers with copper catalysts and environmentally friendly reducing agents.

Recent Advances in Polymeric Materials Used as Electron Mediators and Immobilizing Matrices in Developing Enzyme Electrodes

PubMed Central

Moyo, Mambo; Okonkwo, Jonathan O.; Agyei, Nana M.

2012-01-01

Different classes of polymeric materials such as nanomaterials, sol-gel materials, conducting polymers, functional polymers and biomaterials have been used in the design of sensors and biosensors. Various methods have been used, for example from direct adsorption, covalent bonding, crossing-linking with glutaraldehyde on composites to mixing the enzymes or use of functionalized beads for the design of sensors and biosensors using these polymeric materials in recent years. It is widely acknowledged that analytical sensing at electrodes modified with polymeric materials results in low detection limits, high sensitivities, lower applied potential, good stability, efficient electron transfer and easier immobilization of enzymes on electrodes such that sensing and biosensing of environmental pollutants is made easier. However, there are a number of challenges to be addressed in order to fulfill the applications of polymeric based polymers such as cost and shortening the long laboratory synthetic pathways involved in sensor preparation. Furthermore, the toxicological effects on flora and fauna of some of these polymeric materials have not been well studied. Given these disadvantages, efforts are now geared towards introducing low cost biomaterials that can serve as alternatives for the development of novel electrochemical sensors and biosensors. This review highlights recent contributions in the development of the electrochemical sensors and biosensors based on different polymeric material. The synergistic action of some of these polymeric materials and nanocomposites imposed when combined on electrode during sensing is discussed. PMID:22368503

Use of recycled fine aggregate in concretes with durable requirements.

PubMed

Zega, Claudio Javier; Di Maio, Angel Antonio

2011-11-01

The use of construction waste materials as aggregates for concrete production is highly attractive compared to the use of non-renewable natural resources, promoting environmental protection and allowing the development of a new raw material. Several countries have recommendations for the use of recycled coarse aggregate in structural concrete, whereas the use of the fine fraction is limited because it may produce significant changes in some properties of concrete. However, during the last decade the use of recycled fine aggregates (RFA) has achieved a great international interest, mainly because of economic implications related to the shortage of natural sands suitable for the production of concrete, besides to allow an integral use of this type of waste. In this study, the durable behaviour of structural concretes made with different percentage of RFA (0%, 20%, and 30%) is evaluated. Different properties related to the durability of concretes such as absorption, sorptivity, water penetration under pressure, and carbonation are determined. In addition, the results of compressive strength, static modulus of elasticity and drying shrinkage are presented. The obtained results indicate that the recycled concretes have a suitable resistant and durable behaviour, according to the limits indicated by different international codes for structural concrete. Copyright © 2011 Elsevier Ltd. All rights reserved.

Evaluation of waste concrete road materials for use in oyster aquaculture - phase 3 : research summary.

DOT National Transportation Integrated Search

2016-08-01

The use of recycled materials has gained increased attention for the environmental benefits, and the reuse of industrial by-products and waste materials can provide a stream of revenue for producers and a durable, cost-effective material option for e...

Enhancing aerobic digestion potential of municipal waste-activated sludge through removal of extracellular polymeric substance.

PubMed

Merrylin, J; Kaliappan, S; Kumar, S Adish; Yeom, Ick-Tae; Banu, J Rajesh

2014-01-01

A protease-secreting bacteria was used to pretreat municipal sewage sludge to enhance aerobic digestion. To enhance the accessibility of the sludge to the enzyme, extracellular polymeric substances were removed using citric acid thereby removing the flocs in the sludge. The conditions for the bacterial pretreatment were optimized using response surface methodology. The results of the bacterial pretreatment indicated that the suspended solids reduction was 18% in sludge treated with citric acid and 10% in sludge not treated with citric acid whereas in raw sludge, suspended solids reduction was 5.3%. Solubilization was 10.9% in the sludge with extracellular polymeric substances removed in contrast to that of the sludge with extracellular polymeric substances, which was 7.2%, and that of the raw sludge, which was just 4.8%. The suspended solids reduction in the aerobic reactor containing pretreated sludge was 52.4% whereas that in the control reactor was 15.3%. Thus, pretreatment with the protease-secreting bacteria after the removal of extracellular polymeric substances is a cost-effective and environmentally friendly method.

The fabrication of small molecule organic light-emitting diode pixels by laser-induced forward transfer

NASA Astrophysics Data System (ADS)

Shaw-Stewart, J. R. H.; Mattle, T.; Lippert, T. K.; Nagel, M.; Nüesch, F. A.; Wokaun, A.

2013-01-01

Laser-induced forward transfer (LIFT) is a versatile organic light-emitting diode (OLED) pixel deposition process, but has hitherto been applied exclusively to polymeric materials. Here, a modified LIFT process has been used to fabricate small molecule Alq3 organic light-emitting diodes (SMOLEDs). Small molecule thin films are considerably more mechanically brittle than polymeric thin films, which posed significant challenges for LIFT of these materials. The LIFT process presented here uses a polymeric dynamic release layer, a reduced environmental pressure, and a well-defined receiver-donor gap. The Alq3 pixels demonstrate good morphology and functionality, even when compared to conventionally fabricated OLEDs. The Alq3 SMOLED pixel performances show a significant amount of fluence dependence, not observed with polymerical OLED pixels made in previous studies. A layer of tetrabutyl ammonium hydroxide has been deposited on top of the aluminium cathode, as part of the donor substrate, to improve electron injection to the Alq3, by over 600%. These results demonstrate that this variant of LIFT is applicable for the deposition of functional small molecule OLEDs as well as polymeric OLEDs.

The effects of charge, polymerization, and cluster size on the diffusivity of dissolved Si species in pore water

NASA Astrophysics Data System (ADS)

Yokoyama, Tadashi; Sakuma, Hiroshi

2018-03-01

Silicon (Si) is the most abundant cation in crustal rocks. The charge and degree of polymerization of dissolved Si significantly change depending on solution pH and Si concentration. We used molecular dynamics (MD) simulations to predict the self-diffusion coefficients of dissolved Si, DSi, for 15 monomeric and polymeric species at ambient temperature. The results showed that DSi decreased with increasing negative charge and increasing degree of polymerization. The relationship between DSi and charge (Z) can be expressed by DSi/10-6 = 2.0 + 9.8e0.47Z, and that between DSi and number of polymerization (NSi) by DSi/10-6 = 9.7/NSi0.56. The results also revealed that multiple Si molecules assembled into a cluster and D decreased as the cluster size increased. Experiments to evaluate the diffusivity of Si in pore water revealed that the diffusion coefficient decreased with increasing Si concentration, a result consistent with the MD simulations. Simulation results can now be used to quantitatively assess water-rock interactions and water-concrete reactions over a wide range of environmentally relevant conditions.

Low NO/x/ heavy fuel combustor program

NASA Technical Reports Server (NTRS)

Lister, E.; Niedzwiecki, R. W.; Nichols, L.

1980-01-01

The paper deals with the 'Low NO/x/ Heavy Fuel Combustor Program'. Main program objectives are to generate and demonstrate the technology required to develop durable gas turbine combustors for utility and industrial applications, which are capable of sustained, environmentally acceptable operation with minimally processed petroleum residual fuels. The program will focus on 'dry' reductions of oxides of nitrogen (NO/x/), improved combustor durability and satisfactory combustion of minimally processed petroleum residual fuels. Other technology advancements sought include: fuel flexibility for operation with petroleum distillates, blends of petroleum distillates and residual fuels, and synfuels (fuel oils derived from coal or shale); acceptable exhaust emissions of carbon monoxide, unburned hydrocarbons, sulfur oxides and smoke; and retrofit capability to existing engines.

All-inorganic large-area low-cost and durable flexible perovskite solar cells using copper foil as a substrate.

PubMed

Abdollahi Nejand, B; Nazari, P; Gharibzadeh, S; Ahmadi, V; Moshaii, A

2017-01-05

Here, a low-cost perovskite solar cell using CuI and ZnO as the respective inorganic hole and electron transport layers is introduced. Copper foil is chosen as a cheap and low-weight conductive substrate which has a similar work function to ITO. Besides, copper foil is an interesting copper atom source for the growth of the upper cuprous iodide layer on copper foil. A spray coating of a transparent silver nanowire electrode is used as a top contact. The prepared device shows a maximum power conversion efficiency of 12.80% and long-term durability providing an environmentally and market friendly perovskite solar cell.

Low NO(x) heavy fuel combustor program

NASA Technical Reports Server (NTRS)

Lister, E.; Niedzwiecki, R. W.; Nichols, L.

1979-01-01

The 'low nitrogen oxides heavy fuel combustor' program is described. Main program objectives are to generate and demonstrate the technology required to develop durable gas turbine combustors for utility and industrial applications, which are capable of sustained, environmentally acceptable operation with minimally processed petroleum residual fuels. The program will focus on 'dry' reductions of oxides of nitrogen, improved combustor durability, and satisfactory combustion of minimally processed petroleum residual fuels. Other technology advancements sought include: fuel flexibility for operation with petroleum distillates, blends of petroleum distillates and residual fuels, and synfuels (fuel oils derived from coal or shale); acceptable exhaust emissions of carbon monoxide, unburned hydrocarbons, sulfur oxides and smoke; and retrofit capability to existing engines.

Durability of aircraft composite materials

NASA Technical Reports Server (NTRS)

Dextern, H. B.

1982-01-01

Confidence in the long term durability of advanced composites is developed through a series of flight service programs. Service experience is obtained by installing secondary and primary composite components on commercial and military transport aircraft and helicopters. Included are spoilers, rudders, elevators, ailerons, fairings and wing boxes on transport aircraft and doors, fairings, tail rotors, vertical fins, and horizontal stabilizers on helicopters. Materials included in the evaluation are boron/epoxy, Kevlar/epoxy, graphite/epoxy and boron/aluminum. Inspection, maintenance, and repair results for the components in service are reported. The effects of long term exposure to laboratory, flight, and outdoor environmental conditions are reported for various composite materials. Included are effects of moisture absorption, ultraviolet radiation, and aircraft fuels and fluids.

Environmental Barrier Coating Fracture, Fatigue and High-Heat-Flux Durability Modeling and Stochastic Progressive Damage Simulation

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Nemeth, Noel N.

2017-01-01

Advanced environmental barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to protect emerging light-weight SiC/SiC ceramic matrix composite (CMC) engine components, further raising engine operating temperatures and performance. Because the environmental barrier coating systems are critical to the performance, reliability and durability of these hot-section ceramic engine components, a prime-reliant coating system along with established life design methodology are required for the hot-section ceramic component insertion into engine service. In this paper, we have first summarized some observations of high temperature, high-heat-flux environmental degradation and failure mechanisms of environmental barrier coating systems in laboratory simulated engine environment tests. In particular, the coating surface cracking morphologies and associated subsequent delamination mechanisms under the engine level high-heat-flux, combustion steam, and mechanical creep and fatigue loading conditions will be discussed. The EBC compostion and archtechture improvements based on advanced high heat flux environmental testing, and the modeling advances based on the integrated Finite Element Analysis Micromechanics Analysis Code/Ceramics Analysis and Reliability Evaluation of Structures (FEAMAC/CARES) program will also be highlighted. The stochastic progressive damage simulation successfully predicts mud flat damage pattern in EBCs on coated 3-D specimens, and a 2-D model of through-the-thickness cross-section. A 2-parameter Weibull distribution was assumed in characterizing the coating layer stochastic strength response and the formation of damage was therefore modeled. The damage initiation and coalescence into progressively smaller mudflat crack cells was demonstrated. A coating life prediction framework may be realized by examining the surface crack initiation and delamination propagation in conjunction with environmental degradation under high-heat-flux and environment load test conditions.

Electrochromic material and electro-optical device using same

DOEpatents

Cogan, Stuart F.; Rauh, R. David

1992-01-01

An oxidatively coloring electrochromic layer of composition M.sub.y CrO.sub.2+x (0.33.ltoreq.y.ltoreq.2.0 and x.ltoreq.2) where M=Li, Na or K with improved transmittance modulation, improved thermal and environmental stability, and improved resistance to degradation in organic liquid and polymeric electrolytes. The M.sub.y CrO.sub.2+x provides complementary optical modulation to cathodically coloring materials in thin-film electrochromic glazings and electrochromic devices employing polymeric Li.sup.+ ion conductors.

Electrochromic material and electro-optical device using same

DOEpatents

Cogan, S.F.; Rauh, R.D.

1992-01-14

An oxidatively coloring electrochromic layer of composition M[sub y]CrO[sub 2+x] (0.33[le]y[le]2.0 and x[le]2) where M=Li, Na or K with improved transmittance modulation, improved thermal and environmental stability, and improved resistance to degradation in organic liquid and polymeric electrolytes. The M[sub y]CrO[sub 2+x] provides complementary optical modulation to cathodically coloring materials in thin-film electrochromic glazings and electrochromic devices employing polymeric Li[sup +] ion conductors. 12 figs.

Covalent Immobilization of (-)-Riboflavin on Polymer Functionalized Silica Particles: Application in the Photocatalytic E→Z Isomerization of Polarized Alkenes.

PubMed

Metternich, Jan B; Sagebiel, Sven; Lückener, Anne; Lamping, Sebastian; Ravoo, Bart Jan; Gilmour, Ryan

2018-03-20

The covalent immobilization of the biomimetic, photo-organocatalyst (-)-riboflavin on silica micro- and nanoparticles via atom transfer radical polymerization (ATRP) is disclosed. Given the effectiveness of (-)-riboflavin as a versatile, environmentally benign photocatalyst, an immobilization strategy based on acrylate-linker modification of the catalyst core and controlled polymerization on initiator pre-functionalized silica particles has been developed. Validation of this approach is demonstrated in the E→Z isomerization of a benchmark cinnamonitrile (Z/E up to 88:12) with 0.97 mol % catalyst loading. Characterization of the immobilized photocatalyst supports covalent embedding of the catalyst in the polymeric brushes on the silica particle surface. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical characterization of selected LDEF polymeric materials

NASA Technical Reports Server (NTRS)

Young, Philip R.; Slemp, Wayne S.

1991-01-01

Chemical characterization of selected polymeric materials which received exposure on the Long Duration Exposure Facility (LDEF) is reported. The specimens examined include silvered fluorinated ethylene propylene Teflon thermal blanket material, polysulfone, epoxy, polyimide matrix resin/graphite fiber reinforced composites, and several high performance polymer films. These specimens came from numerous LDEF locations, and thus received different environmental exposures. The results to date show no significant change at the molecular level in the polymer that survived exposure. Scanning electron and scanning tunneling microscopes show resin loss and a texturing of some specimens which resulted in a change in optical properties. The potential effect of a silicon-containing molecular contamination on these materials is addressed. The possibility of continued post-exposure degradation of some polymeric films is also proposed.

Chapter 16: Soy Proteins as Wood Adhesives

Treesearch

Charles R. Frihart; Christopher G. Hunt; Michael J. Birkeland

2014-01-01

Protein adhesives allowed the development of bonded wood products such as plywood and glulam in the early 20th century. Petrochemical-based adhesives replaced proteins in most wood bonding applications because of lower cost, improved production efficiencies, and enhanced durability. However, several technological and environmental factors have led to a resurgence of...

Development and deregulation of the plum pox virus resistant transgenic plum 'HoneySweet'

USDA-ARS?s Scientific Manuscript database

We have demonstrated that genetic engineering can be an important source of high level and durable resistance against Plum pox virus (PPV). We have shown, through a number of field studies, the environmental safety of this genetically engineered plum. Nevertheless, the utilization of this demonstr...

Photovoltaic module electrical termination design requirement study

NASA Technical Reports Server (NTRS)

Mosna, F. J., Jr.; Donlinger, J.

1980-01-01

Pertinent electrical termination attributes were identified and used in the development of selection criteria which included function, environmental durability, utility, manufacturing, code, and cost. Significant aspects of each criteria are discussed, and eight different types of terminations are ranked according to their performance in remote, residential, intermediate, and industrial applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hacke, P.; Terwilliger, K.; Koch, S.

Three crystalline silicon module designs were distributed in five replicas each to five laboratories for testing according to the IEC 62804 (Committee Draft) system voltage durability qualification test for crystalline silicon photovoltaic (PV) modules. The stress tests were performed in environmental chambers at 60 degrees C, 85% relative humidity, 96 h, and with module nameplate system voltage applied.

Mechanical Properties and Durability of Advanced Environmental Barrier Coatings in Calcium-Magnesium-Alumino-Silicate Environments

NASA Technical Reports Server (NTRS)

Miladinovich, Daniel S.; Zhu, Dongming

2011-01-01

Environmental barrier coatings are being developed and tested for use with SiC/SiC ceramic matrix composite (CMC) gas turbine engine components. Several oxide and silicate based compositons are being studied for use as top-coat and intermediate layers in a three or more layer environmental barrier coating system. Specifically, the room temperature Vickers-indentation-fracture-toughness testing and high-temperature stability reaction studies with Calcium Magnesium Alumino-Silicate (CMAS or "sand") are being conducted using advanced testing techniques such as high pressure burner rig tests as well as high heat flux laser tests.

The Dependence of Atomic Oxygen Undercutting of Protected Polyimide Kapton(tm) H upon Defect Size

NASA Technical Reports Server (NTRS)

Snyder, Aaron; deGroh, Kim K.

2001-01-01

Understanding the behavior of polymeric materials when exposed to the low-Earth-orbit (LEO) environment is important in predicting performance characteristics such as in-space durability. Atomic oxygen (AO) present in LEO is known to be the principal agent in causing undercutting erosion of SiO(x) protected polyimide Kapton(R) H film, which serves as a mechanically stable blanket material in solar arrays. The rate of undercutting is dependent on the rate of arrival, directionality and energy of the AO with respect to the film surface. The erosion rate also depends on the distribution of the size of defects existing in the protective coating. This paper presents results of experimental ground testing using low energy, isotropic AO flux together with numerical modeling to determine the dependence of undercutting erosion upon defect size.

The MISSE-9 Polymers and Composites Experiment Being Flown on the MISSE-Flight Facility

NASA Technical Reports Server (NTRS)

De Groh, Kim K.; Banks, Bruce A.

2017-01-01

Materials on the exterior of spacecraft in low Earth orbit (LEO) are subject to extremely harsh environmental conditions, including various forms of radiation (cosmic rays, ultraviolet, x-ray, and charged particle radiation), micrometeoroids and orbital debris, temperature extremes, thermal cycling, and atomic oxygen (AO). These environmental exposures can result in erosion, embrittlement and optical property degradation of susceptible materials, threatening spacecraft performance and durability. To increase our understanding of space environmental effects such as AO erosion and radiation induced embrittlement of spacecraft materials, NASA Glenn has developed a series of experiments flown as part of the Materials International Space Station Experiment (MISSE) missions on the exterior of the International Space Station (ISS). These experiments have provided critical LEO space environment durability data such as AO erosion yield values for many materials and mechanical properties changes after long term space exposure. In continuing these studies, a new Glenn experiment has been proposed, and accepted, for flight on the new MISSE-Flight Facility (MISSE-FF). This experiment is called the Polymers and Composites Experiment and it will be flown as part of the MISSE-9 mission, the inaugural mission of MISSE-FF. Figure 1 provides an artist rendition of MISSE-FF ISS external platform. The MISSE-FF is manifested for launch on SpaceX-13.

Upper Temperature Limit of Environmental Barrier Coatings Based on Mullite and BSAS

NASA Technical Reports Server (NTRS)

Lee, Kang N.; Fox, Dennis S.; Eldridge, Jeffrey I.; Zhu, Dongming; Bansal, Narottam P.; Miller, Robert A.; Robinson, Raymond C.

2002-01-01

Current state-of-the-art environmental barrier coatings (EBCs) for Si-based ceramics consist of three layers: a silicon bond coat, an intermediate mullite (3Al2O3-2SiO2) or mullite + BSAS (1-xBaO-xSrO-Al2O3-2SiO2) layer, and a BSAS top coat. Areas of concern for long-term durability are environmental durability, chemical compatibility, silica volatility, phase stability, and thermal conductivity. Variants of this family of EBCs were applied to monolithic SiC and melt infiltrated SiC/SiC composites. Reaction between BSAS and silica results in low melting (approx. 1300 C) glasses at T > 1400 C, which can cause the spallation of the EBC. At temperatures greater than 1400 C, the BSAS top coat also degrades by formation of a porous structure, and it suffers significant recession via silica volatilization in water vapor-containing atmospheres. All of these degradation mechanisms can be EBC life-limiting factors. BSAS undergoes a very sluggish phase transformation (hexagonal celsian to monoclinic celsian), the implications of which are not fully understood at this point. There was evidence of rapid sintering at temperatures as low as 1300 C, as inferred from the sharp increase in thermal conductivity.

Development and Property Evaluation of Selected HfO2-Silicon and Rare Earth-Silicon Based Bond Coats and Environmental Barrier Coating Systems for SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2016-01-01

Ceramic environmental barrier coatings (EBC) and SiC/SiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiC/SiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, high strength and high temperature capable environmental barrier coating bond coat systems, since the current silicon bond coat cannot meet the advanced EBC-CMC temperature and stability requirements. In this paper, advanced NASA HfO2-Si and rare earth Si based EBC bond coat EBC systems for SiC/SiC CMC combustor and turbine airfoil applications are investigated. High temperature properties of the advanced EBC systems, including the strength, fracture toughness, creep and oxidation resistance have been studied and summarized. The advanced NASA EBC systems showed some promise to achieve 1500C temperature capability, helping enable next generation turbine engines with significantly improved engine component temperature capability and durability.

Polymeric Nanoparticles as a Metolachlor Carrier: Water-Based Formulation for Hydrophobic Pesticides and Absorption by Plants.

PubMed

Tong, Yujia; Wu, Yan; Zhao, Caiyan; Xu, Yong; Lu, Jianqing; Xiang, Sheng; Zong, Fulin; Wu, Xuemin

2017-08-30

Pesticide formulation is highly desirable for effective utilization of pesticide and environmental pollution reduction. Studies of pesticide delivery system such as microcapsules are developing prosperously. In this work, we chose polymeric nanoparticles as a pesticide delivery system and metolachlor was used as a hydrophobic pesticide model to study water-based mPEG-PLGA nanoparticle formulation. Preparation, characterization results showed that the resulting nanoparticles enhanced "water solubility" of hydrophobic metolachlor and contained no organic solvent or surfactant, which represent one of the most important sources of pesticide pollution. After the release study, absorption of Cy5-labeled nanoparticles into rice roots suggested a possible transmitting pathway of this metolachlor formulation and increased utilization of metolachlor. Furthermore, the bioassay test demonstrated that this nanoparticle showed higher effect than non-nano forms under relatively low concentrations on Oryza sativa, Digitaria sanguinalis. In addition, a simple cytotoxicity test involving metolachlor and metolachlor-loaded nanoparticles was performed, indicating toxicity reduction of the latter to the preosteoblast cell line. All of these results showed that those polymeric nanoparticles could serve as a pesticide carrier with lower environmental impact, comparable effect, and effective delivery.

Iron-Based Redox Polymerization of Acrylic Acid for Direct Synthesis of Hydrogel/Membranes, and Metal Nanoparticles for Water Treatment

PubMed Central

Hernández, Sebastián; Papp, Joseph K.; Bhattacharyya, Dibakar

2014-01-01

Functionalized polymer materials with ion exchange groups and integration of nano-structured materials is an emerging area for catalytic and water pollution control applications. The polymerization of materials such as acrylic acid often requires persulfate initiator and a high temperature start. However, is generally known that metal ions accelerate such polymerizations starting from room temperature. If the metal is properly selected, it can be used in environmental applications adding two advantages simultaneously. This paper deals with this by polymerizing acrylic acid using iron as accelerant and its subsequent use for nanoparticle synthesis in hydrogel and PVDF membranes. Characterizations of hydrogel, membranes and nanoparticles were carried out with different techniques. Nanoparticles sizes of 30–60 nm were synthesized. Permeability and swelling measurements demonstrate an inverse relationship between hydrogel mesh size (6.30 to 8.34 nm) and membrane pores (222 to 110 nm). Quantitative reduction of trichloroethylene/chloride generation by Fe/Pd nanoparticles in hydrogel/membrane platforms was also performed. PMID:24954975

Polymeric Coatings for Combating Biocorrosion

NASA Astrophysics Data System (ADS)

Guo, Jing; Yuan, Shaojun; Jiang, Wei; Lv, Li; Liang, Bin; Pehkonen, Simo O.

2018-03-01

Biocorrosion has been considered as big trouble in many industries and marine environments due to causing great economic loss. The main disadvantages of present approaches to prevent corrosion include being limited by environmental factors, being expensive, inapplicable to field, and sometimes inefficient. Studies show that polymer coatings with anti-corrosion and anti-microbial properties have been widely accepted as a novel and effective approach to preventbiocorrosion. The main purpose of this review is to summarize up the progressive status of polymer coatings used for combating microbially-induced corrosion. Polymers used to synthesize protective coatings are generally divided into three categories: i) traditional polymers incorporated with biocides, ii) antibacterial polymers containing quaternary ammonium compounds, and iii) conductive polymers. The strategies to synthesize polymer coatings resort mainly to grafting anti-bacterial polymers from the metal substrate surface using novel surface-functionalization approaches, such as free radical polymerization, chemically oxidative polymerization and surface-initiated atom transfer radical polymerization, as opposed to the traditional approaches of dip coating or spin coating.

Fabrication of core-shell structured magnetic nanocellulose base polymeric ionic liquid for effective biosorption of Congo red dye.

PubMed

Beyki, Mostafa Hossein; Bayat, Mehrnoosh; Shemirani, Farzaneh

2016-10-01

Ionic liquids are considered to be a class of environmentally friendly compounds as combination of them with bioresource polymeric substances such as; cellulose, constitute emerging coating materials. Biosorption by polymeric ionic liquids exhibits an attractive green way that involves low cost and irrespective of toxicity. As a result, a novel polymeric ionic liquid has been developed by the reaction of one step synthesized Fe3O4-cellulose nanohybrid, epichlorohydrin and 1-methylimidazole and employed as a green sorbent for efficient biosorption of Congo red dye. Effective parameters on dye removing as well as their interactions were determined with response surface methodology (RSM). Congo red adsorption showed fast equilibrium time (11min) with maximum uptake of 131mgg(-1). Isotherm study revealed that Langmuir adsorption model can better describe dye adsorption behavior. Regeneration of the sorbent was performed with a mixture of methanol-acetone-NaOH (3.0molL(-1)) solution. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mapping Polymerization and Allostery of Hemoglobin S Using Point Mutations

PubMed Central

Weinkam, Patrick; Sali, Andrej

2014-01-01

Hemoglobin is a complex system that undergoes conformational changes in response to oxygen, allosteric effectors, mutations, and environmental changes. Here, we study allostery and polymerization of hemoglobin and its variants by application of two previously described methods: (i) AllosMod for simulating allostery dynamics given two allosterically related input structures and (ii) a machine-learning method for dynamics- and structure-based prediction of the mutation impact on allostery (Weinkam et al. J. Mol. Biol. 2013), now applicable to systems with multiple coupled binding sites such as hemoglobin. First, we predict the relative stabilities of substates and microstates of hemoglobin, which are determined primarily by entropy within our model. Next, we predict the impact of 866 annotated mutations on hemoglobin’s oxygen binding equilibrium. We then discuss a subset of 30 mutations that occur in the presence of the sickle cell mutation and whose effects on polymerization have been measured. Seven of these HbS mutations occur in three predicted druggable binding pockets that might be exploited to directly inhibit polymerization; one of these binding pockets is not apparent in the crystal structure but only in structures generated by AllosMod. For the 30 mutations, we predict that mutation-induced conformational changes within a single tetramer tend not to significantly impact polymerization; instead, these mutations more likely impact polymerization by directly perturbing a polymerization interface. Finally, our analysis of allostery allows us to hypothesize why hemoglobin evolved to have multiple subunits and a persistent low frequency sickle cell mutation. PMID:23957820

Cyclic Fatigue Durability of Uncoated and EBC Coated 3D SiC/SiC Composites Under Thermal Gradient Conditions at 2700F in Air

NASA Technical Reports Server (NTRS)

Smith, Craig; Harder, Bryan; Zhu, Dongming; Bhatt, Ramakrishna; Kalluri, Sreeramesh

2017-01-01

Ceramic matrix composites (CMCs) such as SiCSiC are currently being designed and implemented in high temperature sections of aerospace turbine engines. Such components will be subject to through-thickness thermal gradients, which may affect the durability. In this study, SiCSiC CMCs with a hybrid chemical vapor infiltrated (CVI) and polymer infiltration and pyrolysis (PIP) matrix were loaded in tension while one surface was heated with a laser and the opposite surface was cooled. The samples were each coated with an environmental barrier coating (EBC), which was produced by electron beam physical deposition (EBPVD). Results for CMCs tested with and without the EBC be discussed.

Hardened, environmentally disposable composite granules of coal cleaning refuse, coal combustion waste, and other wastes, and method preparing the same

DOEpatents

Burnet, George; Gokhale, Ashok J.

1990-07-10

A hardened, environmentally inert and disposable composite granule of coal cleaning refuse and coal combustion waste, and method for producing the same, wherein the coal combustion waste is first granulated. The coal cleaning refuse is pulverized into fine particles and is then bound, as an outer layer, to the granulated coal combustion waste granules. This combination is then combusted and sintered. After cooling, the combination results in hardened, environmentally inert and disposable composite granules having cores of coal combustion waste, and outer shells of coal cleaning refuse. The composite particles are durable and extremely resistant to environmental and chemical forces.

Hardened, environmentally disposable composite granules of coal cleaning refuse, coal combustion waste, and other wastes, and method preparing the same

DOEpatents

Burnet, G.; Gokhale, A.J.

1990-07-10

A hardened, environmentally inert and disposable composite granule of coal cleaning refuse and coal combustion waste and method for producing the same are disclosed, wherein the coal combustion waste is first granulated. The coal cleaning refuse is pulverized into fine particles and is then bound, as an outer layer, to the granulated coal combustion waste granules. This combination is then combusted and sintered. After cooling, the combination results in hardened, environmentally inert and disposable composite granules having cores of coal combustion waste, and outer shells of coal cleaning refuse. The composite particles are durable and extremely resistant to environmental and chemical forces. 3 figs.

Life cycle assessment of Mexican polymer and high-durability cotton paper banknotes.

PubMed

Luján-Ornelas, Cristina; Mancebo Del C Sternenfels, Uriel; Güereca, Leonor Patricia

2018-07-15

This study compares the environmental performance of Mexican banknotes printed on high-durability cotton paper (HD paper) and thermoplastic polymer (polymer) through a life cycle assessment to appraise the environmental impacts from the extraction of raw materials to the final disposal of the banknotes. The functional unit was defined considering the next parameters: 1) lifespan of the banknotes, stablished in 31.5 and 54months for HD paper and polymer, respectively; 2) denomination, selecting $200 pesos banknotes; 3) a 5year time frame and 4) a defined amount of money, in this case stablished as the monthly cash supply of an average Mexican household, equaling $12,708 pesos. Accordingly, 121 pieces for the HD paper and 71 pieces for the polymer banknotes were analyzed. The results favor the banknotes printed on polymer substrate primarily because of the longer lifespan of this type of material; however, there is a considerable environmental impact in the stages of distribution, followed by the extraction of the raw materials (crude oil) during manufacturing. Regarding the HD cotton paper, the major impact corresponds to extraction of the raw materials, followed by the distribution of the banknotes. The inclusion of the automatic teller machines (ATMs) in the life cycle assessment of banknotes shows that the electricity required by these devices became the largest contributor to the environmental impacts. Additionally, the sensitivity analysis that the average lifetime of the banknotes is a determining factor for the environmental impacts associated with the whole life cycle of this product. The life cycle stages that refer to the extraction of the raw materials, combined with the average lifetime of the banknotes and the electricity required during the usage stage, are determining factors in the total environmental impact associated with Mexican banknotes. Copyright © 2018 Elsevier B.V. All rights reserved.

Scalable and durable polymeric icephobic and hydrate-phobic coatings.

PubMed

Sojoudi, Hossein; Arabnejad, Hadi; Raiyan, Asif; Shirazi, Siamack A; McKinley, Gareth H; Gleason, Karen K

2018-05-09

Ice formation and accumulation on surfaces can result in severe problems for solar photovoltaic installations, offshore oil platforms, wind turbines and aircrafts. In addition, blockage of pipelines by formation and accumulation of clathrate hydrates of natural gases has safety and economical concerns in oil and gas operations, particularly at high pressures and low temperatures such as those found in subsea or arctic environments. Practical adoption of icephobic/hydrate-phobic surfaces requires mechanical robustness and stability under harsh environments. Here, we develop durable and mechanically robust bilayer poly-divinylbenzene (pDVB)/poly-perfluorodecylacrylate (pPFDA) coatings using initiated chemical vapor deposition (iCVD) to reduce the adhesion strength of ice/hydrates to underlying substrates (silicon and steel). Utilizing a highly-cross-linked polymer (pDVB) underneath a very thin veneer of fluorine-rich polymer (pPFDA) we have designed inherently rough bilayer polymer films that can be deposited on rough steel substrates resulting in surfaces which exhibit a receding water contact angle (WCA) higher than 150° and WCA hysteresis as low as 4°. Optical profilometer measurements were performed on the films and root mean square (RMS) roughness values of Rq = 178.0 ± 17.5 nm and Rq = 312.7 ± 23.5 nm were obtained on silicon and steel substrates, respectively. When steel surfaces are coated with these smooth hard iCVD bilayer polymer films, the strength of ice adhesion is reduced from 1010 ± 95 kPa to 180 ± 85 kPa. The adhesion strength of the cyclopentane (CyC5) hydrate is also reduced from 220 ± 45 kPa on rough steel substrates to 34 ± 12 kPa on the polymer-coated steel substrates. The durability of these bilayer polymer coated icephobic and hydrate-phobic substrates is confirmed by sand erosion tests and examination of multiple ice/hydrate adhesion/de-adhesion cycles.

Performance and durability of concrete made with demolition waste and artificial fly ash-clay aggregates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zakaria, M.; Cabrera, J.G.

1996-12-31

Demolition aggregates and artificial aggregates made with waste materials are two alternatives being studied for replacement of natural aggregates in the production of concrete. Natural aggregate sources in Europe are increasingly scarce and subject to restrictions based on environmental regulations. In many areas of the developing world sources of good quality aggregates are very limited or practically not available and therefore it has become necessary to study alternative materials. This paper presents a laboratory study on the use of demolition bricks and artificial aggregates made from fly ash-clay as coarse aggregates to make concrete. The concretes made either with demolitionmore » bricks or artificial aggregates are compared with a control mix made with natural gravel aggregates. The strength and durability characteristics of these concretes are evaluated using as a criteria compressive strength and transport properties, such as gas and water permeability. The results show clearly that concretes of good performance and durability can be produced using aggregates from demolition rubble or using artificial aggregates made with wastes such as fly ash.« less

Development and Performance Evaluations of HfO2-Si and Rare Earth-Si Based Environmental Barrier Bond Coat Systems for SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2014-01-01

Ceramic environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiCSiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, high strength and high temperature capable environmental barrier coating bond coat systems, since the current silicon bond coat cannot meet the advanced EBC-CMC temperature and stability requirements. In this paper, advanced NASA HfO2-Si based EBC bond coat systems for SiCSiC CMC combustor and turbine airfoil applications are investigated. The coating design approach and stability requirements are specifically emphasized, with the development and implementation focusing on Plasma Sprayed (PS) and Electron Beam-Physic Vapor Deposited (EB-PVD) coating systems and the composition optimizations. High temperature properties of the HfO2-Si based bond coat systems, including the strength, fracture toughness, creep resistance, and oxidation resistance were evaluated in the temperature range of 1200 to 1500 C. Thermal gradient heat flux low cycle fatigue and furnace cyclic oxidation durability tests were also performed at temperatures up to 1500 C. The coating strength improvements, degradation and failure modes of the environmental barrier coating bond coat systems on SiCSiC CMCs tested in simulated stress-environment interactions are briefly discussed and supported by modeling. The performance enhancements of the HfO2-Si bond coat systems with rare earth element dopants and rare earth-silicon based bond coats are also highlighted. The advanced bond coat systems, when integrated with advanced EBC top coats, showed promise to achieve 1500 C temperature capability, helping enable next generation turbine engines with significantly improved engine component temperature capability and long-term durability.

pH-sensitive Itaconic acid based polymeric hydrogels for dye removal applications.

PubMed

Sakthivel, M; Franklin, D S; Guhanathan, S

2016-12-01

A series of Itaconic Acid (IA) based pH-sensitive polymeric hydrogels were synthesized by condensation polymerization of Itaconic Acid (IA) with Ethylene Glycol (EG) in the presence of an acid medium resulted into pre-polymer. Further, pre-polymer were co-polymerized with Acrylic Acid (AA) through free radical polymerization using Potassium persulphate (KPS). The structural and surface morphological characterizations of the synthesized hydrogels were studied using FT-IR spectroscopy and Scanning Electron Microscope (SEM) respectively. The swelling and swelling equilibrium were performed at varies pH (4.0-10.0). Further, the effects of IA, EG and AA on swelling properties have also been investigated. Thermal stability of synthesized hydrogels have been investigated by TGA, DTA and DSC. The synthesized hydrogels have shown good ability to uptake a Cationic dye. The Methylene blue has been chosen as a model cationic dye. The results of dye removal using IA hydrogels found to have excellent dye removal capacity. Such kind of IA based hydrogels may be recommended for eco-friendly environmental application. viz., removal of dyes and metal ions and sewage water treatment, purification of water etc. Copyright © 2015 Elsevier Inc. All rights reserved.

Understanding cracking failures of coatings: A fracture mechanics approach

NASA Astrophysics Data System (ADS)

Kim, Sung-Ryong

A fracture mechanics analysis of coating (paint) cracking was developed. A strain energy release rate (G(sub c)) expression due to the formation of a new crack in a coating was derived for bending and tension loadings in terms of the moduli, thicknesses, Poisson's ratios, load, residual strain, etc. Four-point bending and instrumented impact tests were used to determine the in-situ fracture toughness of coatings as functions of increasing baking (drying) time. The system used was a thin coating layer on a thick substrate layer. The substrates included steel, aluminum, polycarbonate, acrylonitrile-butadiene-styrene (ABS), and Noryl. The coatings included newly developed automotive paints. The four-point bending configuration promoted nice transversed multiple coating cracks on both steel and polymeric substrates. The crosslinked type automotive coatings on steel substrates showed big cracks without microcracks. When theoretical predictions for energy release rate were compared to experimental data for coating/steel substrate samples with multiple cracking, the agreement was good. Crosslinked type coatings on polymeric substrates showed more cracks than theory predicted and the G(sub c)'s were high. Solvent evaporation type coatings on polymeric substrates showed clean multiple cracking and the G(sub c)'s were higher than those obtained by tension analysis of tension experiments with the same substrates. All the polymeric samples showed surface embrittlement after long baking times using four-point bending tests. The most apparent surface embrittlement was observed in the acrylonitrile-butadiene-styrene (ABS) substrate system. The impact properties of coatings as a function of baking time were also investigated. These experiments were performed using an instrumented impact tester. There was a rapid decrease in G(sub c) at short baking times and convergence to a constant value at long baking times. The surface embrittlement conditions and an embrittlement toughness were found upon impact loading. This analysis provides a basis for a quantitative approach to measuring coating toughness.

Effect of surface preparation on the failure load of a highly filled composite bonded to the polymer-monomer matrix of a fiber-reinforced composite.

PubMed

Shimizu, Hiroshi; Tsue, Fumitake; Chen, Zhao-Xun; Takahashi, Yutaka

2009-04-01

The purpose of the present study was to evaluate the effect of surface preparation on the maximum fracture load value of a highly filled composite bonded to the polymer-monomer matrix of a fiber-reinforced composite. A polymer-monomer matrix was made by mixing urethane dimethacrylate and triethyleneglycol dimethacrylate at a ratio of 1:1 with camphorquinone and 2-dimethylaminoethyl methacrylate as a light initiator. The matrix was then polymerized in a disk-shaped silicone mold with a light-polymerizing unit. The flat surfaces of the polymer-monomer matrix disk were prepared in one of the following ways: (1) without preparation; (2) application of silane coupling agent; or (3) application of matrix liquid and prepolymerization. A highly filled composite material was applied and polymerized with a light-polymerizing unit. Additional test specimens made entirely of the polymer-monomer matrix were fabricated as references; the disk and cylinder were fabricated in one piece using a mold specially made for the present study (group 4). Half the specimens were thermocycled up to 10,000 times in water with a 1-minute dwell time at each temperature (5 degrees C and 55 degrees C). The maximum fracture load values were determined using a universal testing machine (n = 10). The maximum fracture loads for group 3 were significantly enhanced both before and after thermocycling, whereas the maximum fracture loads of group 2 were significantly enhanced before thermocycling (p < 0.05); however, the failure loads decreased for all groups after thermocycling (p < 0.05). All the specimens in groups 1 and 2 debonded during thermocycling. The failure load of group 3 was significantly lower than that of group 4 both before and after thermocycling (p < 0.05). Within the limitations of the current in vitro study, the application and prepolymerization of a mixed dimethacrylate resin liquid prior to the application of a highly filled composite was an effective surface preparation for the polymer-monomer matrix of a fiber-reinforced composite; however, the bond durability may be insufficient.

Effect of boron waste on the properties of mortar and concrete.

PubMed

Topçu, Iker Bekir; Boga, Ahmet Raif

2010-07-01

Utilization of by-products or waste materials in concrete production are important subjects for sustainable development and industrial ecology concepts. The usages as mineral admixtures or fine aggregates improve the durability properties of concrete and thus increase the economic and environmental advantages for the concrete industry. The effect of clay waste (CW) containing boron on the mechanical properties of concrete was investigated. CW was added in different proportions as cement additive in concrete. The effect of CW on workability and strength of concrete were analysed by fresh and hardened concrete tests. The results obtained were compared with control concrete properties and Turkish standard values. The results showed that the addition of CW had a small effect upon the workability of the concrete but an important effect on the reduction of its strength. It was observed that strength values were quite near to that of control concrete when not more than 10% CW was used in place of cement. In addition to concrete specimens, replacing cement with CW produced mortar specimens, which were investigated for their strength and durability properties. The tests of SO( 4) (2-) and Cl(-) effect as well as freeze-thaw behaviour related to the durability of mortar were performed. Consequently, it can be said that some improvements were obtained in durability properties even if mechanical properties had decreased with increasing CW content.

Study on the effect of polymeric rheology modifier on the rheological properties of oil-based drilling fluids

NASA Astrophysics Data System (ADS)

Ma, C.; Li, L.; Yang, Y. P.; Hao, W. W.; Zhang, Q.; Lv, J.

2018-01-01

A new type of polymeric rheology modifier was synthesized by suspension polymerization, and the effect of rheology modifier on the rheological properties of oil-based drilling fluids was investigated. The results indicated that the obtained polymer had good capacity of improvement of shearing force of oil-based drilling fluids under high temperature and high pressure conditions. Moreover, the obtained polymer can improve the stability of oil-based drilling fluids greatly. As a result, the obtained polymer is a good rheology modifier for oil-based drilling fluids, and it can optimize oil-based drilling fluid system with good rheological properties, good static suspension ability for cuttings and environmental protection function. It can play an essential role in safe drilling jobs and improvement of drilling efficiency.

40 CFR 86.1844-01 - Information requirements: Application for certification and submittal of information upon request.

Code of Federal Regulations, 2014 CFR

2014-07-01

... of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES General Compliance Provisions for Control of Air... description of the durability group in accordance with the criteria listed in § 86.1820-01, or as otherwise...

Ground Vehicle Power and Mobility Overview - Germany Visit

DTIC Science & Technology

2011-11-10

the current and future force Survivability Robotics – Intelligent Systems Vehicle Electronics & Architecture Fuel, Water, Bridging ...Test Cell • Engine Generator Test Lab • Full Vehicle Environmental Test Cell • Hybrid Electric Reconfigurable Moveable Integration Testbed (HERMIT...Converter Conducted competitive runoff evaluations on Bridging Boat engine candidates Completed independent durability assessment of OEM

40 CFR 86.1826-01 - Assigned deterioration factors for small volume manufacturers and small volume test groups.

Code of Federal Regulations, 2012 CFR

2012-07-01

... durability groups) that is equipped with unproven emission control systems. (v) The manufacturer must... small volume manufacturers and small volume test groups. 86.1826-01 Section 86.1826-01 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW...

40 CFR 86.1826-01 - Assigned deterioration factors for small volume manufacturers and small volume test groups.

Code of Federal Regulations, 2013 CFR

2013-07-01

... durability groups) that is equipped with unproven emission control systems. (v) The manufacturer must... small volume manufacturers and small volume test groups. 86.1826-01 Section 86.1826-01 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW...

40 CFR 86.1826-01 - Assigned deterioration factors for small volume manufacturers and small volume test groups.

Code of Federal Regulations, 2011 CFR

2011-07-01

... durability groups) that is equipped with unproven emission control systems. (v) The manufacturer must... small volume manufacturers and small volume test groups. 86.1826-01 Section 86.1826-01 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW...

40 CFR 86.1826-01 - Assigned deterioration factors for small volume manufacturers and small volume test groups.

Code of Federal Regulations, 2010 CFR

2010-07-01

... durability groups) that is equipped with unproven emission control systems. (v) The manufacturer must... small volume manufacturers and small volume test groups. 86.1826-01 Section 86.1826-01 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW...

Design and evaluation of high-volume fly ash (HVFA) concrete mixes, report E : hardened mechanical properties and durability performance of HVFA concrete.

DOT National Transportation Integrated Search

2012-10-01

A rising concern in todays construction industry is environmental responsibility. : The addition of fly ash is a leading innovation in sustainable design of concrete. Fly ash, : a waste by-product of coal burning power plants, can be used to repla...

[Upgrading of complete removable prosthetic appliance of stomatological patients by the use of new base materials].

PubMed

Кузь, Виталий С; Дворник, Валентин Н; Тесленко, Александра И; Кузь, Гельфира М; Мартыненко, Игорь Н

2016-01-01

The effectiveness of orthopedic treatment of edentulous patients depends on the properties of the basic materials. The main group of materials for manufacturing of such structures are acrylic plastics of thermal polymerization. However, many years of experience in the use of plastics has revealed a number of shortcomings. One of the main is insufficient functional durability of prostheses, and as a consequence - the fragility of acrylic constructions. At present, more and more dentists use nonacrylic thermoplastics, which can improve the functional quality of full removable dentures, as well as, avoid the above disadvantages of acrylic basic plastic. The work is devoted to the study of comparative clinical effectiveness of dental prosthetic in edentulous patients using a variety of basic materials for the production of removable dentures. In this work we used the following materials - "Ftorax" - acrylic plastic of hot polymerization and «Vertex Thermosense» - nonacrylic thermoplastic plastic. As a result of the performed work it can be concluded that the use of the basic thermoplastic materials, namely «Vertex Thermosense», allows to get more rapid adaptation of the patient to full removable dentures due to better fixation and stabilization. Based on the results of our comparative clinical study it can be recommended using of base material «Vertex Thermosense» in the clinic of prosthetic dentistry in treatment of edentulous patients.

Casting Molding of PDCPD Material for Purpose of Car’s Power Steering Body

NASA Astrophysics Data System (ADS)

Grabowski, L.; Baier, A.; Sobek, M.

2018-01-01

The growing industry of polymer and composite materials is facing new challenges posed by the automotive industry. In this industry, traditional materials such as steel and aluminum are widely replaced with plastic materials, including polymers. In the past, such behavior concerned design and interior elements, but more and more often plastics are used in the case of load-bearing elements, i.e. those that require high strength and durability nowadays. This kind of materials are also often used in safety systems or driver assistance systems. Therefore, the aim of the activities described in this article are to carry out an innovative process of injection of cold polymeric material, PDCPD (Polidicyclopentadiene), polymerizing with the use of Metathesis reaction, which in 2005 was awarded the Nobel Prize. This injection applies to the worm gear components of the system, supports the power steering system of the passenger car. Also the process of selecting the appropriate parameters to carry out this process, guaranteeing the best quality of the obtained elements is necessary. The aim of the activities was to achieve a fully useful power steering support system, using a polymer body, which is replacing the aluminum. These activities were aimed at reducing the costs and weight of the final product. The injection process and the way to achieve the finished product were carried out in an innovative way, never used in industry before.

Shuttle Suppression by Polymer-Sealed Graphene-Coated Polypropylene Separator.

PubMed

Ou, Xuewu; Yu, Yanzi; Wu, Ruizhe; Tyagi, Abhishek; Zhuang, Minghao; Ding, Yao; Abidi, Irfan Haider; Wu, Hengan; Wang, Fengchao; Luo, Zhengtang

2018-02-14

"Shuttle effect" of lithium polysulfides (LiPS) leads to a poor performance and a short cycle life of the Li-S battery, thus limiting their practical application. We demonstrate here that after coating polypropylene (PP) separator with a continuous monolayer graphene, the shuttle effect can be significantly suppressed by limiting the passage of long-chain LiPS. The graphene/PP separator can be further modified by sealing the big holes or pores on graphene with in situ polymerized nylon-66 via an interfacial polymerization reaction between diamine and adipoyl chloride supplied by the aqueous and oil phase, respectively, from each side of the membrane. With this engineered membrane, an initial specific capacity of 1128.4 mAh g -1 at 0.05C is achieved after test in a coin cell, higher than that of 983.2 mAh g -1 with pristine PP, along with increased Coulombic efficiency from 96.0 to 99.9% and enhanced cycling durability. Molecular dynamics simulations attest that the nanopores with appropriate size and structure are effective in acting as a "sieve" to selectively allow only Li + ions to pass through but prevent LiPS from migrating to the anode, consequently alleviating the shuttle effect. Our method provides a facile solution toward the mitigated shuttle effect and eventually contributes to the high performance of Li-S battery.

Transparent, Weakly Conductive Films for Space Applications

NASA Astrophysics Data System (ADS)

Griffin, John; Morgan, Ashraf; Hambourger, Paul

2004-10-01

Electrically insulating spacecraft surfaces are vulnerable to nonuniform charge buildup due to particles emitted by the sun. On Mars, insulating surfaces of exploration vehicles and structures will be affected by dust coatings possibly held in place by triboelectric surface charge. Application of a conductive film may be a solution to the charging problem, but the coating must be highly transparent if used on solar panels, lenses, etc. Sheet resistivity requirements depend on the application and are in the range 10^2-10^8 ohms/square. Co-deposited indium tin oxide (ITO) and MgF2 is promising, with high transparency, tailorable electrical properties, and durability to atomic oxygen.(Joyce A. Dever et al., NASA TM 1998-208499 (August 1998).) Due to ITO's relatively narrow bandgap ( ˜3.5 eV), the film might absorb enough ultraviolet to protect polymeric substrates. Recent work on dual-magnetron-sputtered ITO-MgF2 showed that a variety of polymeric substrates can be coated at room temperature.(Thomas Cashman et al., Vacuum Technology & Coating, September 2003, p. 38.) However, the sheet resistivity is very sensitive to composition, suggestive of a percolation transition. This could be a serious problem for large-scale coating production. We will report on attempts to control film composition by plasma emission monitoring of the ITO and MgF2 guns. Supported by NASA Glenn Research Center, Cooperative Agreements NCC3-1033 and NCC3-1065.

Chelating Polymers and Environmental Remediation

DTIC Science & Technology

2009-03-01

remediation, nanotechnology 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 22 19a. NAME OF RESPONSIBLE PERSON...interest in nanotechnology as well as biomaterials and biomimetic systems appears to be shaping the future of polymeric environmental remediation (18...in nanotechnology is not expected until the cost is commensurate to conventional technologies. 13 6. References 1. Kostal, J.; Prabhukumar

Photochemical removal of aniline in aqueous solutions: switching from photocatalytic degradation to photo-enhanced polymerization recovery.

PubMed

Tang, Heqing; Li, Jing; Bie, Yeqiang; Zhu, Lihua; Zou, Jing

2010-03-15

Organic pollutants may be treated by either a degradation process or a recovery process in the view point of sustainable chemistry. Photocatalytic removal of aniline was investigated in aqueous solutions. It was found that the photocatalytic oxidation of aniline resulted in its degradation or polymerization, depending on its concentration. Hence a new treatment strategy was proposed in combination of photocatalytic degradation and polymerization, where the polymerization was in fact a recovery process. When aniline concentration was as low as 0.1 mmol L(-1), it was possible to photocatalytically degrade aniline, which could be further enhanced by increasing solution pH, modifying TiO(2) surface with the addition of anions, or coupling with the photoreduction of added oxidants. When aniline concentration was increased to about 1 mmol L(-1), the photocatalytic oxidation was observed to yield the polymerization of aniline, leading to nanocomposites of polyaniline (PAN) and TiO(2). Alternatively, the photo-enhanced chemical polymerization of aniline at higher concentrations (>or=50 mmol L(-1)) in the presence of chemical oxidants produced PAN nanostructures. The conversion of pollutant aniline to valuable PAN nanostructures or nano-PAN/TiO(2) composites is suggestive for possible applications in the treatment of aniline wastewaters as a sustainable environmental protection measure. (c) 2009 Elsevier B.V. All rights reserved.

Advanced Environmental Barrier Coating Development for SiC-SiC Ceramic Matrix Composite Components

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna; Kiser, Doug; Wiesner, Valerie L.

2016-01-01

This presentation reviews the NASA advanced environmental barrier coating (EBC) system development for SiCSiC Ceramic Matrix Composite (CMC) components for next generation turbine engines. The emphasis has been placed on the current design challenges of the 2700F environmental barrier coatings; coating processing and integration with SiCSiC CMCs and component systems; and performance evaluation and demonstration of EBC-CMC systems. This presentation also highlights the EBC-CMC system temperature capability and durability improvements through advanced compositions and architecture designs, as shown in recent simulated engine high heat flux, combustion environment, in conjunction with mechanical creep and fatigue loading testing conditions.

A comparison of stresses in molar teeth restored with inlays and direct restorations, including polymerization shrinkage of composite resin and tooth loading during mastication.

PubMed

Dejak, Beata; Młotkowski, Andrzej

2015-03-01

Polymerization shrinkage of composites is one of the main causes of leakage around dental restorations. Despite the large numbers of studies there is no consensus, what kind of teeth reconstruction--direct or indirect composite restorations are the most beneficial and the most durable. The aim was to compare equivalent stresses and contact adhesive stresses in molar teeth with class II MOD cavities, which were restored with inlays and direct restorations (taking into account polymerization shrinkage of composite resin) during simulated mastication. The study was conducted using the finite elements method with the application of contact elements. Three 3D models of first molars were created: model A was an intact tooth; model B--a tooth with a composite inlay, and model C--a tooth with a direct composite restoration. Polymerization linear shrinkage 0.7% of a direct composite restoration and resin luting cement was simulated (load 1). A computer simulation of mastication was performed (load 2). In these 2 situations, equivalent stresses according to the modified von Mises criterion (mvM) in the materials of mandibular first molar models with different restorations were calculated and compared. Contact stresses in the luting cement-tooth tissue adhesive interface around the restorations were also assessed and analyzed. Equivalent stresses in a tooth with a direct composite restoration (the entire volume of which was affected by polymerization shrinkage) were many times higher than in the tooth restored with a composite inlay (where shrinkage was present only in a thin layer of the luting cement). In dentin and enamel the stress values were 8-14 times higher, and were 13 times higher in the direct restoration than in the inlay. Likewise, contact stresses in the adhesive bond around the direct restoration were 6.5-7.7 times higher compared to an extraorally cured restoration. In the masticatory simulation, shear contact stresses in the adhesive bond around the direct composite restoration reached the highest values 32.8 MPa and significantly exceeded the shear strength of the connection between the resin luting cement and the tooth structure. Equivalent stresses in the tooth structures restored with inlays and in the restoration material itself and contact stresses at the tooth-luting cement adhesive interface are many times lower compared to teeth with direct composite restorations. Teeth with indirect restorations are potentially less susceptible to damage compared to those with direct restorations. Composite inlays also ensure a better seal compared to direct restorations. Polymerization shrinkage determines stress levels in teeth with direct restorations, while its impact on adhesion in indirectly restored teeth is insignificant. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Materials International Space Station Experiment (MISSE): Overview, Accomplishments and Future Needs

NASA Technical Reports Server (NTRS)

deGroh, Kim K.; Jaworske, Donald A.; Pippin, Gary; Jenkins, Philip P.; Walters, Robert J.; Thibeault, Sheila A.; Palusinski, Iwona; Lorentzen, Justin R.

2014-01-01

Materials and devices used on the exterior of spacecraft in low Earth orbit (LEO) are subjected to environmental threats that can cause degradation in material properties, possibly threatening spacecraft mission success. These threats include: atomic oxygen (AO), ultraviolet and x-ray radiation, charged particle radiation, temperature extremes and thermal cycling, micrometeoroid and debris impacts, and contamination. Space environmental threats vary greatly based on spacecraft materials, thicknesses and stress levels, and the mission environment and duration. For more than a decade the Materials International Space Station Experiment (MISSE) has enabled the study of the long duration environmental durability of spacecraft materials in the LEO environment. The overall objective of MISSE is to test the stability and durability of materials and devices in the space environment in order to gain valuable knowledge on the performance of materials in space, as well as to enable lifetime predictions of new materials that may be used in future space flight. MISSE is a series of materials flight experiments, which are attached to the exterior of the International Space Station (ISS). Individual experiments were loaded onto suitcase-like trays, called Passive Experiment Containers (PECs). The PECs were transported to the ISS in the Space Shuttle cargo bay and attached to, and removed from, the ISS during extravehicular activities (EVAs). The PECs were retrieved after one or more years of space exposure and returned to Earth enabling post-flight experiment evaluation. MISSE is a multi-organization project with participants from the National Aeronautics and Space Administration (NASA), the Department of Defense (DoD), industry and academia. MISSE has provided a platform for environmental durability studies for thousands of samples and numerous devices, and it has produced many tangible impacts. Ten PECs (and one smaller tray) have been flown, representing MISSE 1 through MISSE 8, yielding long-duration space environmental performance and durability data that enable material validation, processing recertification and space qualification; improved predictions of materials and component lifetimes in space; model verification and development; and correlation factors between space-exposure and ground-facilities enabling more accurate in-space performance predictions based on ground-laboratory testing. A few of the many experiment results and observations, and their impacts, are provided. Those highlighted include examples on improved understanding of atomic oxygen scattering mechanisms, LEO coating durability results, and polymer erosion yields and their impacts on spacecraft design. The MISSE 2 Atomic Oxygen Scattering Chamber Experiment discovered that the peak flux of scattered AO was determined to be 45 deg from normal incidence, not the model predicted cosine dependence. In addition, the erosion yield (E(sub y)) of Kapton H for AO scattered off oxidized-Al is 22% of the E(sub y) of direct AO impingement. These results were used to help determine the degradation mechanism of a cesium iodide detector within the Hubble Space Telescope Cosmic Origins Spectrograph Experiment. The MISSE 6 Indium Tin Oxide (ITO) Degradation Experiment measured surface electrical resistance of ram and wake ITO coated samples. The data confirmed that ITO is a stable AO protective coating, and the results validated the durability of ITO conductive coatings for solar arrays for the Atmosphere-Space Transition 2 Explorer program. The MISSE 2, 6 and 7 Polymer Experiments have provided LEO AO Ey data on over 120 polymer and composites samples. The flight E(sub y) values were found to range from 3.05 x 10(exp -26) cu cm/atom for the AO resistant polymer CORIN to 9.14 x 10(exp -26) cu cm/atom for polyoxymethylene (POM). In addition, flying the same polymers on different missions has advanced the understanding of the AO E(sub y) dependency on solar exposure for polymers containing fluorine. The MISSE polymer results are highly requested and have impacted spacecraft design for WorldView-2 & -3, the Global Precipitation Measurement-Microwave Imager, and other spacecraft. The flight data has enabled the development of an Atomic Oxygen Erosion Predictive Tool that allows the erosion prediction of new and non-flown polymers. The data has also been used to develop a new NASA Technical Standards Handbook "Spacecraft Polymers Atomic Oxygen Durability Handbook." Many intangible benefits have also been derived from MISSE. For example, over 40 students have collaborated on Glenn's MISSE experiments, which have resulted in greater than $80K in student scholarships and awards in national and international science fairs. Students have also given presentations and won poster competition awards at international space conferences.

Composite chitosan hydrogels for extended release of hydrophobic drugs.

PubMed

Delmar, Keren; Bianco-Peled, Havazelet

2016-01-20

A composite chitosan hydrogel durable in physiological conditions intended for sustained release of hydrophobic drugs was investigated. The design is based on chitosan crosslinked with genipin with embedded biocompatible non-ionic microemulsion (ME). A prolonged release period of 48 h in water, and of 24h in phosphate buffer saline (PBS) of pH 7.4 was demonstrated for Nile red and curcumin. The differences in release patterns in water and PBS were attributed to distinct dissimilarities in the swelling behaviors; in water, the hydrogels swell enormously, while in PBS they expel water and shrink. The release mechanism dominating this system is complex due to intermolecular bonding between the oil droplets and the polymeric network, as confirmed by Fourier transform infrared spectroscopy (FTIR) experiments. This is the first time that oil in water microemulsions were introduced into a chitosan hydrogels for the creation of a hydrophobic drug delivery system. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis and Properties of Cross-Linked Polyamide Aerogels

NASA Technical Reports Server (NTRS)

Williams, Jarrod C.; Meador, Mary Ann; McCorkle, Linda

2015-01-01

We report the first synthesis of cross-linked polyamide aerogels through step growth polymerization using a combination of diamines, diacid chloride and triacid chloride. Polyamide oligomers endcapped with amines are prepared as stable solutions in N-methylpyrrolidinone from several different diamine precursors and 1,3-benzenedicarbonyl dichloride. Addition of 1,3,5-benzenetricarbonyl trichloride yields gels which form in under five minutes according to the scheme shown. Solvent exchange of the gels into ethanol, followed by drying using supercritical CO2 extraction gives colorless aerogels with densities around 0.1 to 0.2 gcm3. Thicker monolithes of the polyamide aerogels are stiff and strong, while thin films of certain formulations are highly flexible, durable, and even translucent. These materials may have use as insulation for deployable space structures, rovers, habitats or extravehicular activity suits as well as in many terrestrial applications. Strucure property relationships of the aerogels, including surface area, mechanical properties, and thermal conductivity will be discussed.

Graphite nanoplatelet enabled embeddable fiber sensor for in situ curing monitoring and structural health monitoring of polymeric composites.

PubMed

Luo, Sida; Liu, Tao

2014-06-25

A graphite nanoplatelet (GNP) thin film enabled 1D fiber sensor (GNP-FibSen) was fabricated by a continuous roll-to-roll spray coating process, characterized by scanning electron microscopy and Raman spectroscopy and evaluated by coupled electrical-mechanical tensile testing. The neat GNP-FibSen sensor shows very high gauge sensitivity with a gauge factor of ∼17. By embedding the sensor in fiberglass prepreg laminate parts, the dual functionalities of the GNP-FibSen sensor were demonstrated. In the manufacturing process, the resistance change of the embedded sensor provides valuable local resin curing information. After the manufacturing process, the same sensor is able to map the strain/stress states and detect the failure of the host composite. The superior durability of the embedded GNP-FibSen sensor has been demonstrated through 10,000 cycles of coupled electromechanical tests.

Synthesis and properties of immobilized pectinase onto the macroporous polyacrylamide microspheres.

PubMed

Lei, Zhongli; Jiang, Qin

2011-03-23

Pectinase was covalently immobilized onto the macroporous polyacrylamide (PAM) microspheres synthesized via an inverse suspension polymerization approach, resulting in 81.7% immobilization yield. The stability of the macroporous PAM support, which has a large surface area, is not impeded by the adsorbed proteins despite the fact that up to 296.3 mg of enzyme is immobilized per gram of the carrier particles. The immobilized enzyme retained more than 75% of its initial activity over 30 days, and the optimum temperature/pH also increased to the range of 50-60 °C/3.0-5.0. The immobilized enzyme also exhibited great operational stability, and more than 75% residual activity was observed after 10 batch reactions. The kinetics of a model reaction catalyzed by the immobilized pectinase was finally investigated. Moreover, the immobilized pectinase could be recovered by centrifuging and showed durable activity at the process of recycle.

Principles of Sustainable Prevention: Designing Scale-Up of School-Wide Positive Behavior Support to Promote Durable Systems

ERIC Educational Resources Information Center

McIntosh, Kent; Filter, Kevin J.; Bennett, Joanna L.; Ryan, Charlotte; Sugai, George

2010-01-01

In this article, we provide an overview of School-wide Positive Behavior Support (SWPBS), an approach to building protective school cultures and preventing the development of problem behavior through instruction, environmental redesign, and attention to systems-level variables. We define the critical features of SWPBS within a prevention science…

Environmental Degradation of Fiber-Reinforced Polymer Fasteners in Wood

Treesearch

Samuel L. Zelinka; Douglas R. Rammer

2013-01-01

This paper examines the durability of fiber-reinforced polymer (FRP) nails in treated wood. The FRP nails were exposed to four conditions: (1) accelerated weathering, consisting of exposure to ultraviolet light and condensation; (2) 100% relative humidity (RH); (3) being driven into untreated wood and exposed to 100% RH; and (4) being driven into wood treated with...

Introduction to session on materials and structures

NASA Technical Reports Server (NTRS)

Vosteen, L. F.

1978-01-01

A review was given of the development of composites for aircraft. Supporting base technology and the Aircraft Energy Efficiency Composites Program are included. Specific topics discussed include: (1) environmental effects on materials; (2) material quality and chemical characterization; (3) design and analysis methods; (4) structural durability; (5) impact sensitivity; (6) carbon fiber electrical effects; and (7) composite components.

Wood as a sustainable building material

Treesearch

Robert H. Falk

2009-01-01

Few building materials possess the environmental benefits of wood. It is not only the most widely used building material in the United States but also one with characteristics that make it suitable for a wide range of applications. Efficient, durable, and useful wood products produced from trees range from a minimally processed log at a log-home building site to a...

Wood as a sustainable building material

Treesearch

Robert H. Falk

2010-01-01

Few building materials possess the environmental benefits of wood. It is not only our most widely used building material but also one with characteristics that make it suitable for a wide range of applications. As described in the many chapters of this handbook, efficient, durable, and useful wood products produced from trees can range from a minimally processed log at...

Chapter 14: Evaluating the Leaching of Biocides from Preservative-Treated Wood Products

Treesearch

Stan T. Lebow

2014-01-01

Leaching of biocides is an important consideration in the long term durability and any potential for environmental impact of treated wood products. This chapter discusses factors affecting biocide leaching, as well as methods of evaluating rate and quantity of biocide released. The extent of leaching is a function of preservative formulation, treatment methods, wood...

NREL Scientists Demonstrate Remarkable Stability in Perovskite Solar Cells

Science.gov Websites

environmentally stable, high-efficiency perovskite solar cell, bringing the emerging technology a step closer to needed to make the devices durable enough for long-term use. NREL's unencapsulated solar cell-a cell used Unencapsulated Perovskite Solar Cells for >1000 Hours of Operational Stability." "A solar cell in

Environmental Technology Verification Report and Statement for Baghouse Filtration Products, W. L. Gore & Associates, Inc. 5117 High Durability PPS Laminate Filtration Media (Tested March-April 2012)

EPA Science Inventory

Baghouses are air pollution control devices used to control particulate emissions from stationary sources and are among the technologies evaluated by the APCT Center. Baghouses and their accompanying filter media have long been one of the leading particulate control techniques fo...

Evaluating the natural durability of native and tropical wood species against Reticulitermes flavipes

Treesearch

R.A. Arango; F. Green; K. Hintz; R.B. Miller

2004-01-01

Environmental pressures to eliminate arsenate from wood preservatives has resulted in voluntary removal of CCA for residential applications in the United States. A new generation of copper organic preservatives has been formulated to replace CCA for decking and in-ground applications but there is no guarantee that these preservatives represent a permanent solution to...

Ceramic Integration Technologies for Energy and Aerospace Applications

NASA Technical Reports Server (NTRS)

Singh, Mrityunjay; Asthana, Ralph N.

2007-01-01

Robust and affordable integration technologies for advanced ceramics are required to improve the performance, reliability, efficiency, and durability of components, devices, and systems based on them in a wide variety of energy, aerospace, and environmental applications. Many thermochemical and thermomechanical factors including joint design, analysis, and optimization must be considered in integration of similar and dissimilar material systems.

Natural durability of tropical and native woods against termite damage by Reticulitermes flavipes (Kollar)

Treesearch

Rachel A. Arango; Frederick Green; Kristina Hintz; Patricia K. Lebow; Regis B. Miller

2006-01-01

Environmental pressure has resulted in voluntary removal of chromated copper arsenate (CCA) from wood preservatives in residential applications in the United States. A new generation of copper organic preservatives was formulated as replacements, but these preservatives may not provide a permanent solution to all related problems. Some of these issues include concern...

Durability and Damage Tolerance of High Temperature Polymeric Composites

NASA Technical Reports Server (NTRS)

Case, Scott W.; Reifsnider, Kenneth L.

1996-01-01

Modern durability and damage tolerance predictions for composite material systems rely on accurate estimates of the local stress and material states for each of the constituents, as well as the manner in which the constituents interact. In this work, an number of approaches to estimating the stress states and interactions are developed. First, an elasticity solution is presented for the problem of a penny-shaped crack in an N-phase composite material system opened by a prescribed normal pressure. The stress state around such a crack is then used to estimate the stress concentrations due to adjacent fiber fractures in composite materials. The resulting stress concentrations are then used to estimate the tensile strength of the composite. The predicted results are compared with experimental values. In addition, a cumulative damage model for fatigue is presented. Modifications to the model are made to include the effects of variable amplitude loading. These modifications are based upon the use of remaining strength as a damage metric and the definition of an equivalent generalized time. The model is initially validated using results from the literature. Also, experimental data from APC-2 laminates and IM7/K3B laminates are used in the model. The use of such data for notched laminates requires the use of an effective hole size, which is calculated based upon strain distribution measurements. Measured remaining strengths after fatigue loading are compared with the predicted values for specimens fatigued at room temperature and 350 F (177 C).

Posterior composite restoration update: focus on factors influencing form and function

PubMed Central

Bohaty, Brenda S; Ye, Qiang; Misra, Anil; Sene, Fabio; Spencer, Paulette

2013-01-01

Restoring posterior teeth with resin-based composite materials continues to gain popularity among clinicians, and the demand for such aesthetic restorations is increasing. Indeed, the most common aesthetic alternative to dental amalgam is resin composite. Moderate to large posterior composite restorations, however, have higher failure rates, more recurrent caries, and increased frequency of replacement. Investigators across the globe are researching new materials and techniques that will improve the clinical performance, handling characteristics, and mechanical and physical properties of composite resin restorative materials. Despite such attention, large to moderate posterior composite restorations continue to have a clinical lifetime that is approximately one-half that of the dental amalgam. While there are numerous recommendations regarding preparation design, restoration placement, and polymerization technique, current research indicates that restoration longevity depends on several variables that may be difficult for the dentist to control. These variables include the patient’s caries risk, tooth position, patient habits, number of restored surfaces, the quality of the tooth–restoration bond, and the ability of the restorative material to produce a sealed tooth–restoration interface. Although clinicians tend to focus on tooth form when evaluating the success and failure of posterior composite restorations, the emphasis must remain on advancing our understanding of the clinical variables that impact the formation of a durable seal at the restoration–tooth interface. This paper presents an update of existing technology and underscores the mechanisms that negatively impact the durability of posterior composite restorations in permanent teeth. PMID:23750102

Tribo-functionalizing Si and SU8 materials by surface modification for application in MEMS/NEMS actuator-based devices

NASA Astrophysics Data System (ADS)

Singh, R. A.; Satyanarayana, N.; Kustandi, T. S.; Sinha, S. K.

2011-01-01

Micro/nano-electro-mechanical-systems (MEMS/NEMS) are miniaturized devices built at micro/nanoscales. At these scales, the surface/interfacial forces are extremely strong and they adversely affect the smooth operation and the useful operating lifetimes of such devices. When these forces manifest in severe forms, they lead to material removal and thereby reduce the wear durability of the devices. In this paper, we present a simple, yet robust, two-step surface modification method to significantly enhance the tribological performance of MEMS/NEMS materials. The two-step method involves oxygen plasma treatment of polymeric films and the application of a nanolubricant, namely perfluoropolyether. We apply the two-step method to the two most important MEMS/NEMS structural materials, namely silicon and SU8 polymer. On applying surface modification to these materials, their initial coefficient of friction reduces by ~4-7 times and the steady-state coefficient of friction reduces by ~2.5-3.5 times. Simultaneously, the wear durability of both the materials increases by >1000 times. The two-step method is time effective as each of the steps takes the time duration of approximately 1 min. It is also cost effective as the oxygen plasma treatment is a part of the MEMS/NEMS fabrication process. The two-step method can be readily and easily integrated into MEMS/NEMS fabrication processes. It is anticipated that this method will work for any kind of structural material from which MEMS/NEMS are or can be made.

Waste Isolation Pilot Plant Salt Decontamination Testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rick Demmer; Stephen Reese

2014-09-01

On February 14, 2014, americium and plutonium contamination was released in the Waste Isolation Pilot Plant (WIPP) salt caverns. At the request of WIPP’s operations contractor, Idaho National Laboratory (INL) personnel developed several methods of decontaminating WIPP salt, using surrogate contaminants and also americium (241Am). The effectiveness of the methods is evaluated qualitatively, and to the extent possible, quantitatively. One of the requirements of this effort was delivering initial results and recommendations within a few weeks. That requirement, in combination with the limited scope of the project, made in-depth analysis impractical in some instances. Of the methods tested (dry brushing,more » vacuum cleaning, water washing, strippable coatings, and mechanical grinding), the most practical seems to be water washing. Effectiveness is very high, and it is very easy and rapid to deploy. The amount of wastewater produced (2 L/m2) would be substantial and may not be easy to manage, but the method is the clear winner from a usability perspective. Removable surface contamination levels (smear results) from the strippable coating and water washing coupons found no residual removable contamination. Thus, whatever is left is likely adhered to (or trapped within) the salt. The other option that shows promise is the use of a fixative barrier. Bartlett Nuclear, Inc.’s Polymeric Barrier System (PBS) proved the most durable of the coatings tested. The coatings were not tested for contaminant entrapment, only for coating integrity and durability.« less

Influence of the association of the EVA and NBR on the characteristics of modified bitumen

NASA Astrophysics Data System (ADS)

Bensaada, A.; Soudani, K.; Haddadi, S.; Saoula, S.

2015-03-01

Durability and the performance of pavement depend mainly on the characteristics of materials which change over time like all other organic substances. They are subject to significant changes due to environmental conditions during the different phases of use. In the present work we investigated experimentally the influence of the association of ethyl vinyl acetate polymer (EVA) with an industrial waste, acrylonitrile-butadiene rubber (NBR) on the modification of bitumen AC 35-50 and its rheological behavior. The incorporation of NBR and EVA in the bitumen improved its intrinsic characteristics (softening point, penetration and ductility). In addition to improving the characteristics of bituminous binders that will affect the durability of bituminous structures, the environment will be preserved by the recycling of industrial waste.

Novel Phenylethynyl Imide Silanes as Coupling Agents for Titanium Alloy

NASA Technical Reports Server (NTRS)

Park, C.; Lowther, S. E.; Smith, J. G., Jr.; Conell, J. W.; Hergenrother, P. M.; SaintClair, T. L.

2004-01-01

The durability of titanium (Ti) alloys bonded with high temperature adhesives such as polyimides has failed to attain the level of performance required for many applications. The problem to a large part is attributed to the instability of the surface treatment on the Ti substrate. Although Ti alloy adhesive specimens with surface treatments such as chromic acid anodization, Pasa-Jell, Turco, etc. have provided high initial mechanical properties, these properties have decreased as a function of aging at ambient temperature and faster, when aged at elevated temperatures or in a hot-wet environment. As part of the High Speed Civil Transport program where Ti honeycomb sandwich structure must perform for 60,000 hours at 177 C, work was directed to the development of environmentally safe, durable Ti alloy surface treatments.

Lunar and Martian environmental interactions with nuclear power system radiators

NASA Technical Reports Server (NTRS)

Perez-Davis, Marla E.; Gaier, James R.; Katzan, Cynthia M.

1992-01-01

Future NASA space missions include a permanent manned presence on the moon and an expedition to the planet Mars. Such steps will require careful consideration of environmental interactions in the selection and design of required power systems. Several environmental constituents may be hazardous to performance integrity. Potential threats common to both the moon and Mars are low ambient temperatures, wide daily temperature swings, solar flux, and large quantities of dust. The surface of Mars provides the additional challenges of dust storms, winds, and a carbon dioxide atmosphere. In this review, the anticipated environmental interactions with surface power system radiators are described, as well as the impacts of these interactions on radiator durability, which were identified at NASA Lewis Research Center.

Importance of microscopy in durability studies of solidified and stabilized contaminated soils

USGS Publications Warehouse

Klich, I.; Wilding, L.P.; Drees, L.R.; Landa, E.R.

1999-01-01

Solidification/stabilization (S/S) is recognized by the U.S. EPA as a best demonstrated available technology for the containment of contaminated soils and other hazardous wastes that cannot be destroyed by chemical, thermal, or biological means. Despite the increased use of S/S technologies, little research has been conducted on the weathering and degradation of solidified and stabilized wastes once the treated materials have been buried. Published data to verify the performance and durability of landfilled treated wastes over time are rare. In this preliminary study, optical and electron microscopy (scanning electron microscopy [SEM], transmission electron microscopy [TEM] and electron probe microanalyses [EPMA]) were used to evaluate weathering features associated with metal-bearing contaminated soil that had been solidified and stabilized with Portland cement and subsequently buried on site, stored outdoors aboveground, or achieved in a laboratory warehouse for up to 6 yr. Physical and chemical alteration processes identified include: freeze-thaw cracking, cracking caused by the formation of expansive minerals such as ettringite, carbonation, and the movement of metals from waste aggregates into the cement micromass. Although the extent of degradation after 6 yr is considered slight to moderate, results of this study show that the same environmental concerns that affect the durability of concrete must be considered when evaluating the durability and permanence of the solidification and stabilization of contaminated soils with cement. In addition, such evaluations cannot be based on leaching and chemical analyses alone. The use of all levels of microscopic analyses must be incorporated into studies of the long-term performance of S/S technologies.Solidification/stabilization (S/S) is recognized by the U.S. EPA as a best demonstrated available technology for the containment of contaminated soils and other hazardous wastes that cannot be destroyed by chemical, thermal, or biological means. Despite the increased use of S/S technologies, little research has been conducted on the weathering and degradation of solidified and stabilized wastes once the treated materials have been buried. Published data to verify the performance and durability of landfilled treated wastes over time are rare. In this preliminary study, optical and electron microscopy (scanning electron microscopy [SEM], transmission electron microscopy [TEM] and electron probe microanalyses [EPMA]) were used to evaluate weathering features associated with metal-bearing contaminated soil that had been solidified and stabilized with Portland cement and subsequently buried on site, stored outdoors aboveground, or archived in a laboratory, warehouse for up to 6 yr. Physical and chemical alteration processes identified include: freeze-thaw cracking, cracking caused by the formation of expansive minerals such as ettringite, carbonation, and the movement of metals from waste aggregates into the cement micromass. Although the extent of degradation after 6 yr is considered slight to moderate, results of this study show that the same environmental concerns that affect the durability of concrete must be considered when evaluating the durability and permanence of the solidification and stabilization of contaminated soils with cement. In addition, such evaluations cannot be based on leaching and chemical analyses alone. The use of all levels of microscopic analyses must be incorporated into studies of the long-term performance of S/S technologies.

Understanding glass formation and ion transport in polymeric ionic liquids using computer simulations

NASA Astrophysics Data System (ADS)

Patra, Tarak; Yang, Junhong; Cheng, Yiz; Simmons, David

Polymeric ionic liquids (PILs) are very promising materials to enable more environmentally stable high density energy storage devices. Realization of PILs providing high environmental and mechanical stability while maximizing ion conductivity would be accelerated by an improved molecular level understanding of their structure and dynamics. Extensive evidence suggests that both mechanical properties and ion conductivity in anhydrous PILs are intimately related to the PIL's glass formation behavior. This represents a major challenge to the rational design of these materials, given that the basic nature of glass formation and its connection to molecular properties remains a substantial open question in polymer and condensed matter physics. Here we describe coarse-grained and atomistic molecular dynamics simulations probing the relationship between PIL architecture and interactions, glass formation behavior, and ion transport characteristics. These studies provide guidance towards the design of PILs with improved stability and ion conductivity for future energy applications.

Chemically Polymerized Polypyrrole for On-Chip Concentration of Volatile Breath Metabolites

PubMed Central

Strand, Nicholas; Bhushan, Abhinav; Schivo, Michael; Kenyon, Nicholas J.; Davis, Cristina E.

2009-01-01

A wide range of metabolites are measured in the gas phase of exhaled human breath, and some of these biomarkers are frequently observed to be up- or down-regulated in certain disease states. Portable breath analysis systems have the potential for a wide range of applications in health diagnostics. However, this is currently limited by the lack of concentration mechanisms to enhance trace metabolites found in the breath to levels that can be adequately recorded using miniaturized gas-phase sensors. In this study we have created chip-based polymeric pre-concentration devices capable of absorbing and desorbing breath volatiles for subsequent chemical analysis. These devices appear to concentrate chemicals from both environmental air samples as well as directly from exhaled human breath, and these devices may have applications in lab-on-a-chip-based environmental and health monitoring systems. PMID:20161533

The environmental roots of non-communicable diseases (NCDs) and the epigenetic impacts of globalization.

PubMed

Vineis, Paolo; Stringhini, Silvia; Porta, Miquel

2014-08-01

Non-communicable diseases (NCDs) are increasing worldwide. We hypothesize that environmental factors (including social adversity, diet, lack of physical activity and pollution) can become "embedded" in the biology of humans. We also hypothesize that the "embedding" partly occurs because of epigenetic changes, i.e., durable changes in gene expression patterns. Our concern is that once such factors have a foundation in human biology, they can affect human health (including NCDs) over a long period of time and across generations. To analyze how worldwide changes in movements of goods, persons and lifestyles (globalization) may affect the "epigenetic landscape" of populations and through this have an impact on NCDs. We provide examples of such changes and effects by discussing the potential epigenetic impact of socio-economic status, migration, and diet, as well as the impact of environmental factors influencing trends in age at puberty. The study of durable changes in epigenetic patterns has the potential to influence policy and practice; for example, by enabling stratification of populations into those who could particularly benefit from early interventions to prevent NCDs, or by demonstrating mechanisms through which environmental factors influence disease risk, thus providing compelling evidence for policy makers, companies and the civil society at large. The current debate on the '25 × 25 strategy', a goal of 25% reduction in relative mortality from NCDs by 2025, makes the proposed approach even more timely. Epigenetic modifications related to globalization may crucially contribute to explain current and future patterns of NCDs, and thus deserve attention from environmental researchers, public health experts, policy makers, and concerned citizens. Copyright © 2014 Elsevier Inc. All rights reserved.

Plasma-initiated polymerization of chitosan-based CS-g-P(AM-DMDAAC) flocculant for the enhanced flocculation of low-algal-turbidity water.

PubMed

Sun, Yongjun; Zhu, Chengyu; Sun, Wenquan; Xu, Yanhua; Xiao, Xuefeng; Zheng, Huaili; Wu, Huifang; Liu, Cuiyun

2017-05-15

In this work, a highly efficient and environmentally friendly chitosan-based graft flocculant, namely, acrylamide- and dimethyl diallyl ammonium chloride-grafted chitosan [CS-g-P(AM-DMDAAC)], was prepared successfully through plasma initiation. FTIR results confirmed the successful polymerization of CS-g-P(AM-DMDAAC) and P(AM-DMDAAC). P(AM-DMDAAC) was the copolymer of acrylamide- and dimethyl diallyl ammonium chloride. SEM results revealed that a densely cross-linked network structure formed on the surface. XRD results verified that the ordered crystal structure of chitosan in CS-g-P(AM-DMDAAC) was changed into an amorphous structure after plasma-induced polymerization. The flocculation results of low-algal-turbidity water further showed the optimal flocculation efficiency of turbidity removal rate, COD removal rate, and Chl-a removal rate were 99.02%, 96.11%, and 92.20%, respectively. The flocculation efficiency of CS-g-P(AM-DMDAAC) were significantly higher than those obtained by cationic polyacrylamide (CPAM) and Polymeric aluminum and iron (PAFC). This work provided a valuable basis for the design of eco-friendly naturally modified polymeric flocculants to enhance the flocculation of low-algal-turbidity water. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhanced mechanical properties of self-polymerized polydopamine-coated recycled PLA filament used in 3D printing

NASA Astrophysics Data System (ADS)

Zhao, Xing Guan; Hwang, Kyung-Jun; Lee, Dongoh; Kim, Taemin; Kim, Namsu

2018-05-01

Dopamine readily adsorbs onto almost all kinds of surfaces and develops cohesive strength through self-polymerization; hence, aqueous solutions of dopamine can be used as adhesives. These properties were used to prevent the degradation in the mechanical properties of recycled PLA fabricated by 3D printer. The mechanical properties of 3D printed PLA play a critical role in determining its applications. To reduce the manufacturing cost as well as environmental pollutants, recycling of 3D printed materials has attracted many attentions. However, recycling of polymeric materials causes the degradation of the mechanical properties. Our study is aimed at advancing the current knowledge on the adhesion behavior of polydopamine coatings on PLA pellets used in 3D printing process. Polydopamine was synthesized by oxidative polymerization and used to coat PLA specimens. The adhesion behavior and mechanical properties of the 3D printed specimens were evaluated by tensile tests. It was found that the mechanical properties of recycled specimen with polydopamine coating have been improved. Microstructural and chemical characterization of the coated specimens was carried out using FE-SEM, FTIR, and XPS analyses.

Research of Tool Durability in Surface Plastic Deformation Processing by Burnishing of Steel Without Metalworking Fluids

NASA Astrophysics Data System (ADS)

Grigoriev, S. N.; Bobrovskij, N. M.; Melnikov, P. A.; Bobrovskij, I. N.

2017-05-01

Modern vector of development of machining technologies aimed at the transition to environmentally safe technologies - “green” technologies. The concept of “green technology” includes a set of signs of knowledge intended for practical use (“technology”). One of the ways to improve the quality of production is the use of surface plastic deformation (SPD) processing methods. The advantage of the SPD is a capability to combine effects of finishing and strengthening treatment. The SPD processing can replace operations: fine turning, grinding or polishing. The SPD is a forceful contact impact of indentor on workpiece’s surface in condition of their relative motion. It is difficult to implement the core technology of the SPD (burnishing, roller burnishing, etc.) while maintaining core technological advantages without the use of lubricating and cooling technology (metalworking fluids, MWF). The “green” SPD technology was developed by the authors for dry processing and has not such shortcomings. When processing with SPD without use of MWF requirements for tool’s durability is most significant, especially in the conditions of mass production. It is important to determine the period of durability of tool at the design stage of the technological process with the purpose of wastage preventing. This paper represents the results of durability research of natural and synthetic diamonds (polycrystalline diamond - ASPK) as well as precision of polycrystalline superabrasive tools made of dense boron nitride (DBN) during SPD processing without application of MWF.

The changes of proteins and polysaccharides in extracellular polymeric substance for Spirogyra fluviatilis under different salinity

NASA Astrophysics Data System (ADS)

Lee, Yichao; Chang, Shuiping

2017-05-01

Spirogyra is a genus of widely distributed, large green fresh water algae. This study discovered that changes in salinity can induce Spirogyra fluviatilis to produce amounts of extracellular polymeric substance (EPS) when controlling other environmental conditions. If culturing S. fluviatilis with salinity greater than a 3.0‰ medium for 4 hours, the secretion EPS will be changed. And the level of polysaccharides and proteins, the primary components of EPS, is slightly increased in accordance with the increase in the salinity. But the proteins to polysaccharides ratio changes are not significantly

Construction of dual-functional polymer nanomaterials with near-infrared fluorescence imaging and polymer prodrug by RAFT-mediated aqueous dispersion polymerization.

PubMed

Tian, Chun; Niu, Jinyun; Wei, Xuerui; Xu, Yujie; Zhang, Lifen; Cheng, Zhenping; Zhu, Xiulin

2018-05-31

The performance of functional polymer nanomaterials is a vigorously discussed topic in polymer science. We devoted ourselves to investigating polymer nanomaterials based on near-infrared (NIR) fluorescence imaging and polymer prodrug in this study. Aza-boron dipyrromethene (BODIPY) is an important organic dye, having characteristics such as environmental resistance, light resistance, high molar extinction coefficient, and fluorescence quantum yield. We incorporated it into our target monomer, which can be polymerized without changing its parent structure in a polar solvent and copolymerized with water-soluble monomer to improve the solubility of the dye in an aqueous solution. At the same time, the hydrophobic drug camptothecin (CPT) was designed as a prodrug monomer, and the polymeric nanoparticles (NPs) with NIR fluorescence imaging and prodrug were synthesized in situ in reversible addition-fragmentation chain transfer (RAFT)-mediated aqueous dispersion polymerization. The dynamic light scattering (DLS) and transmission electron microscopy (TEM) revealed the final uniform size of the dual-functional polymeric NPs morphology. The dual-functional polymeric NPs had a strong absorption and emission signal in the NIR region (>650 nm) based on the fluorescence tests. In consideration of the long-term biological toxicity, confocal laser scanning microscopy (CLSM) results indicated that the dual-functional NPs with controlled drug content exhibited effective capability of killing HeLa cells. In addition, in vivo imaging of the dual-functional NPs was observed in real time, and the fluorescent signals clearly demonstrated the dynamic process of prodrug transfer.

Adsorption equilibrium and dynamics of gasoline vapors onto polymeric adsorbents.

PubMed

Jia, Lijuan; Yu, Weihua; Long, Chao; Li, Aimin

2014-03-01

The emission of gasoline vapors is becoming a significant environmental problem especially for the population-dense area and also results in a significant economic loss. In this study, adsorption equilibrium and dynamics of gasoline vapors onto macroporous and hypercrosslinked polymeric resins at 308 K were investigated and compared with commercial activated carbon (NucharWV-A 1100). The results showed that the equilibrium and breakthrough adsorption capacities of virgin macroporous and hypercrosslinked polymeric resins were lower than virgin-activated carbon. Compared with origin adsorbents, however, the breakthrough adsorption capacities of the regenerated activated carbon for gasoline vapors decreased by 58.5 % and 61.3 % when the initial concentration of gasoline vapors were 700 and 1,400 mg/L, while those of macroporous and hypercrosslinked resins decreased by 17.4 % and 17.5 %, and 46.5 % and 45.5 %, respectively. Due to the specific bimodal property in the region of micropore (0.5-2.0 nm) and meso-macropore (30-70 nm), the regenerated hypercrosslinked polymeric resin exhibited the comparable breakthrough adsorption capacities with the regenerated activated carbon at the initial concentration of 700 mg/L, and even higher when the initial concentration of gasoline vapors was 1,400 mg/L. In addition, 90 % of relative humidity had ignorable effect on the adsorption of gasoline vapors on hypercrosslinked polymeric resin. Taken together, it is expected that hypercrosslinked polymeric adsorbent would be a promising adsorbent for the removal of gasoline vapors from gas streams.

Fatigue behaviour analysis for the durability prequalification of strengthening mortars

NASA Astrophysics Data System (ADS)

Bocca, P.; Grazzini, A.; Masera, D.

2011-07-01

An innovative laboratory procedure used as a preliminary design stage for the pre-qualification of strengthening mortars applied to historical masonry buildings is described. In the analysis of the behaviour of masonry structures and their constituent materials, increasing importance has been assumed by the study of the long-term evolution of deformation and mechanical characteristics, which may be affected by both loading and environmental conditions. Through static and fatigue tests on mixed specimens historical brick-reinforced mortar it has been possible to investigate the durability of strengthening materials, in order to select, from a range of alternatives, the most suitable for the historical masonry. Cyclic fatigue stress has been applied to accelerate the static creep and to forecast the corresponding creep behaviour of the historical brick-strengthening mortar system under static long-time loading. This methodology has proved useful in avoiding the errors associated with materials that are not mechanically compatible and guarantees the durability of strengthening work. The experimental procedure has been used effectively in the biggest restoration building site in Europe, the Royal Palace of Venaria, and it is in progress of carrying out at the Special Natural Reserve of the Sacro Monte di Varallo, in Piedmont (Italy).

Durability Assessment of TiAl Alloys

NASA Technical Reports Server (NTRS)

Draper, Susan L.; Lerch, Bradley A.

2008-01-01

The durability of TiAl is a prime concern for the implementation of TiAl into aerospace engines. Two durability issues, the effect of high temperature exposure on mechanical properties and impact resistance, have been investigated and the results are summarized in this paper. Exposure to elevated temperatures has been shown to be detrimental to the room temperature ductility of gamma alloys with the most likely mechanisms being the ingress of interstitials from the surface. Fluorine ion implantation has been shown to improve the oxidation resistance of gamma alloys, and ideally it could also improve the environmental embrittlement of high Nb content TiAl alloys. The effect of F ion implantation on the surface oxidation and embrittlement of a third generation, high Nb content TiAl alloy (Ti-45Al-5Nb-B-C) were investigated. Additionally, the ballistic impact resistance of a variety of gamma alloys, including Ti-48Al-2Cr- 2Nb, Ti-47Al-2Cr-2Nb, ABB-2, ABB-23, NCG359E, 95A and Ti-45Al-5Nb-B-C was accessed. Differences in the ballistic impact properties of the various alloys will be discussed, particularly with respect to their manufacturing process, microstructure, and tensile properties.

Characterization and genome-wide association mapping of resistance to leaf rust, stem rust and stripe rust in a geographically diverse collection of spring wheat landraces

USDA-ARS?s Scientific Manuscript database

The challenge posed by rapidly changing wheat rust pathogens, both in virulence and in environmental adaptation, calls for the development and application of new techniques to accelerate the process of breeding for durable resistance. To expand the wheat resistance gene pool available for germplasm ...

Comparing energy use and environmental emissions of reinforced wood doors and steel doors

Treesearch

Lynn Knight; Melissa Huff; Janet I. Stockhausen; Robert J. Ross

2005-01-01

The USDA Forest Service Forest Products Laboratory has patented a technology that incorporates fiberglass-reinforced wood into the structure of wood doors and other wood building products. The process of reinforcing wood doors with epoxy and fiberglass increases the strength and durability of the product. Also, it allows the use of low-value, small-diameter wood which...

Environmental Barrier Coating (EBC) Durability Modeling; An Overview and Preliminary Analysis

NASA Technical Reports Server (NTRS)

Abdul-Aziz, A.; Bhatt, R. T.; Grady, J. E.; Zhu, D.

2012-01-01

A study outlining a fracture mechanics based model that is being developed to investigate crack growth and spallation of environmental barrier coating (EBC) under thermal cycling conditions is presented. A description of the current plan and a model to estimate thermal residual stresses in the coating and preliminary fracture mechanics concepts for studying crack growth in the coating are also discussed. A road map for modeling life and durability of the EBC and the results of FEA model(s) developed for predicting thermal residual stresses and the cracking behavior of the coating are generated and described. Further initial assessment and preliminary results showed that developing a comprehensive EBC life prediction model incorporating EBC cracking, degradation and spalling mechanism under stress and temperature gradients typically seen in turbine components is difficult. This is basically due to mismatch in thermal expansion difference between sub-layers of EBC as well as between EBC and substrate, diffusion of moisture and oxygen though the coating, and densification of the coating during operating conditions as well as due to foreign object damage, the EBC can also crack and spall from the substrate causing oxidation and recession and reducing the design life of the EBC coated substrate.

Early stage of weathering of medieval-like potash-lime model glass: evaluation of key factors.

PubMed

Gentaz, Lucile; Lombardo, Tiziana; Loisel, Claudine; Chabas, Anne; Vallotto, Marta

2011-02-01

Throughout history, a consequent part of the medieval stained glass windows have been lost, mostly because of deliberate or accidental mechanic destruction during war or revolution, but, in some cases, did not withstand the test of time simply because of their low durability. Indeed, the glasses that remain nowadays are for many in a poor state of conservation and are heavily deteriorated. Under general exposure conditions, stained glass windows undergo different kinds of weathering processes that modify their optical properties, chemistry, and structure: congruent dissolution, leaching, and particle deposition (the combination of those two leading together to the formation of neocrystallisations and eventually crusts). Previous research has studied the weathering forms and the mechanisms from which they are originated, some others identified the main environmental parameters responsible for the deterioration and highlighted that both intrinsic (glass composition) and extrinsic (environmental parameters) factors influence glass degradation. Nevertheless, a clear quantification of the impact of the different deterioration extrinsic factors has not been performed. By analysing the results obtained with model glass (durable and nondurable) exposed in the field, this paper proposes a simple mathematical computation evaluating the contribution of the different weathering factors for the early stages of exposure of the stained glasses. In the case of non durable glass, water runoff was identified as the main factor inducing the leaching (83.4 ± 2.6% contribution), followed by gas (6.4 ± 1.5%) and particle deposition (6.8 ± 2.2%) and adsorbed water (3.4 ± 0.6%). Moreover, it was shown that the extrinsic stimuli superimposes with the impact of glass composition to the weathering. Those results show that the role played by dry deposition, even if less important than that of the wet deposition, cannot be neglected.

Fibrin Clots Are Equilibrium Polymers That Can Be Remodeled Without Proteolytic Digestion

NASA Astrophysics Data System (ADS)

Chernysh, Irina N.; Nagaswami, Chandrasekaran; Purohit, Prashant K.; Weisel, John W.

2012-11-01

Fibrin polymerization is a necessary part of hemostasis but clots can obstruct blood vessels and cause heart attacks and strokes. The polymerization reactions are specific and controlled, involving strong knob-into-hole interactions to convert soluble fibrinogen into insoluble fibrin. It has long been assumed that clots and thrombi are stable structures until proteolytic digestion. On the contrary, using the technique of fluorescence recovery after photobleaching, we demonstrate here that there is turnover of fibrin in an uncrosslinked clot. A peptide representing the knobs involved in fibrin polymerization can compete for the holes and dissolve a preformed fibrin clot, or increase the fraction of soluble oligomers, with striking rearrangements in clot structure. These results imply that in vivo clots or thrombi are more dynamic structures than previously believed that may be remodeled as a result of local environmental conditions, may account for some embolization, and suggest a target for therapeutic intervention.

Hydrogel nanoparticle based immunoassay

DOEpatents

Liotta, Lance A; Luchini, Alessandra; Petricoin, Emanuel F; Espina, Virginia

2015-04-21

An immunoassay device incorporating porous polymeric capture nanoparticles within either the sample collection vessel or pre-impregnated into a porous substratum within fluid flow path of the analytical device is presented. This incorporation of capture particles within the immunoassay device improves sensitivity while removing the requirement for pre-processing of samples prior to loading the immunoassay device. A preferred embodiment is coreshell bait containing capture nanoparticles which perform three functions in one step, in solution: a) molecular size sieving, b) target analyte sequestration and concentration, and c) protection from degradation. The polymeric matrix of the capture particles may be made of co-polymeric materials having a structural monomer and an affinity monomer, the affinity monomer having properties that attract the analyte to the capture particle. This device is useful for point of care diagnostic assays for biomedical applications and as field deployable assays for environmental, pathogen and chemical or biological threat identification.

Effect of antioxidants on the dentin interface bond stability of adhesives exposed to hydrolytic degradation.

PubMed

Gotti, Valéria B; Feitosa, Victor P; Sauro, Salvatore; Correr-Sobrinho, Lourenço; Leal, Fernanda B; Stansbury, Jeffrey W; Correr, Américo B

2015-02-01

This study assessed the effect of antioxidants vitamin C (Vit. C), vitamin E (Vit. E) and quercetin (Querc) on the dentin bonding performance, degree of conversion, and rate of polymerization of three commercial adhesive systems (Adper Single Bond 2 [SB], Clearfil SE Bond [CSE], Adper Easy Bond [EB]). Human premolars were restored using antioxidant-doped adhesives. The samples were stored for 24 h in distilled water or 6 months under simulated pulpal pressure. Teeth were cut into sticks and the microtensile bond strength (μTBS) to dentin was tested in a universal testing machine. Qualitative nanoleakage analysis was performed from a central stick of each restored tooth. Degree of conversion and rate of polymerization of adhesive systems were evaluated in triplicate using real-time FT-IR. Although the inclusion of the antioxidants negatively affected the μTBS over 24 h, the antioxidant-doped adhesives maintained (SB-Vit. C, SB-Vit. E, CSE-Vit. C, EB-Querc) or increased (SB-Querc, CSE-Vit. E, CSE-Querc, EB-Vit. E, and EB-Vit. C) their μTBS during 6 months of storage. Only the μTBS of Adper Single Bond 2 dropped significantly after 6 months among the control groups. Slight changes in the nanoleakage pattern after aging were observed in all groups, except for the EB-control group, which showed a noteworthy increase in nanoleakage after 6 months, and for EB-Vit. C, which presented a remarkable decrease. A lower degree of conversion was obtained with all antioxidants in SB and EB, except for the EB-Vit. E group. Similar degrees of conversion were attained in control and experimental groups for CSE. The rate of polymerization was reduced in antioxidant-doped adhesives. The performance of antioxidants changed according to the adhesive system to which they were added, and antioxidant-doped adhesives appear to have a positive effect on the adhesive interface durability, since their bond strength obtained after 24 h was maintained or increased over time.

Characterization of Polyimide Foams for Ultra-Lightweight Space Structures

NASA Technical Reports Server (NTRS)

Meador, Michael (Technical Monitor); Hillman, Keithan; Veazie, David R.

2003-01-01

Ultra-lightweight materials have played a significant role in nearly every area of human activity ranging from magnetic tapes and artificial organs to atmospheric balloons and space inflatables. The application range of ultra-lightweight materials in past decades has expanded dramatically due to their unsurpassed efficiency in terms of low weight and high compliance properties. A new generation of ultra-lightweight materials involving advanced polymeric materials, such as TEEK (TM) polyimide foams, is beginning to emerge to produce novel performance from ultra-lightweight systems for space applications. As a result, they require that special conditions be fulfilled to ensure adequate structural performance, shape retention, and thermal stability. It is therefore important and essential to develop methodologies for predicting the complex properties of ultra-lightweight foams. To support NASA programs such as the Reusable Launch Vehicle (RLV), Clark Atlanta University, along with SORDAL, Inc., has initiated projects for commercial process development of polyimide foams for the proposed cryogenic tank integrated structure (see figure 1). Fabrication and characterization of high temperature, advanced aerospace-grade polyimide foams and filled foam sandwich composites for specified lifetimes in NASA space applications, as well as quantifying the lifetime of components, are immensely attractive goals. In order to improve the development, durability, safety, and life cycle performance of ultra-lightweight polymeric foams, test methods for the properties are constant concerns in terms of timeliness, reliability, and cost. A major challenge is to identify the mechanisms of failures (i.e., core failure, interfacial debonding, and crack development) that are reflected in the measured properties. The long-term goal of the this research is to develop the tools and capabilities necessary to successfully engineer ultra-lightweight polymeric foams. The desire is to reduce density at the material and structural levels, while at the same time maintaining or increasing mechanical and other properties.

Pharmacokinetic Modeling Of Perfluorooctanoic Acid During Gestation And Lactation In Mice

EPA Science Inventory

Perfluorooctanoic acid (PFOA) is used industrially as a processing aid in the polymerization of commercially valuable fluoropolymers. Its widespread environmental distribution, presence in human serum, and adverse effects in animal toxicity studies have triggered attention to its...

PHOTOCROSSLINKED IMMOBILIZATION OF POLYELECTROLYTES FOR TEMPLATE ASSISTED ENZYMATIC POLYMERIZATION OF CONJUGATED POLYMERS

EPA Science Inventory

Growing demand in consumer electronics raises need for efficient, affordable, environmentally benign and biodegradable substitutes for current technologies. Printed circuit boards contain heavy metals such as antimony, silver, chromium, zinc, lead, tin and copper. According t...

Perfluorinated Compounds: Emerging POPs with Potential Immunotoxicity

EPA Science Inventory

Perfluorinated compounds (PFCs) have been recognized as an important class of environmental contaminants commonly detected in blood samples of both wildlife and humans. These compounds have been in use for more than 60 years as surface treatment chemicals, polymerization aids, an...

Pharmacokinetic Modeling of Perfluorooctanoic Acid During Gestation and Lactation in the Mouse

EPA Science Inventory

Perfluorooctanoic acid (PFOA) is a processing aid for the polymerization of commercially valuable fluoropolymers. Its widespread environmental distribution, presence in human blood, and adverse effects in animal toxicity studies have triggered attention to its potential adverse e...

Advanced manufacturing development of a composite empennage component for L-1011 aircraft. Phase 3: Production readiness verification testing

NASA Technical Reports Server (NTRS)

Jackson, A.; Sandifer, J.; Sandorff, P.; Vancleave, R.

1984-01-01

Twenty-two specimens of each of two key structural elements of the Advance Composite Vertical Fin (ACVF) were fabricated and tested. One element represented the front spar at the fuselage attachment area and the other element represented the cover at the fuselage joint area. Ten specimens of each element were selected for static testing. The coefficient of variation resulting from the tests was 3.28 percent for the ten cover specimens and 6.11 percent for the ten spar specimens, which compare well with metallic structures. The remaining twelve cover and twelve spar specimens were durability tested in environmental chambers which permitted the temperature and humidity environment to be cycled as well as the applied loads. Results of the durability tests indicated that such components will survive the service environment.

Vacuum ultraviolet radiation and thermal cycling effects on atomic oxygen protective photovoltaic array blanket materials

NASA Technical Reports Server (NTRS)

Brady, J.; Banks, B.

1990-01-01

The importance of synergistic environmental exposure is demonstrated through the evaluation of DuPont 93-1 in simulated LEO environment. Changes in optical properties, surface condition, and mass loss data are described. The qualitative results indicate the necessity for exposure of materials to a series of simulated LEO environments in order to properly determine synergistic effects and demonstrate the overall LEO durability of candidate materials. It is shown that synergistic effects may occur with vacuum thermal cycling combined with VUV radiation followed by atomic oxygen exposure. Testing the durability of candidate solar array blanket materials in a test sequence with necessary synergistic effects makes it possible to determine the appropriate material for providing structural support and maintaining the proper operating temperature for solar cells in the SSF Photovaltaic Power System.

Evaluation of the durability of composite tidal turbine blades.

PubMed

Davies, Peter; Germain, Grégory; Gaurier, Benoît; Boisseau, Amélie; Perreux, Dominique

2013-02-28

The long-term reliability of tidal turbines is critical if these structures are to be cost effective. Optimized design requires a combination of material durability models and structural analyses. Composites are a natural choice for turbine blades, but there are few data available to predict material behaviour under coupled environmental and cycling loading. The present study addresses this problem, by introducing a multi-level framework for turbine blade qualification. At the material scale, static and cyclic tests have been performed, both in air and in sea water. The influence of ageing in sea water on fatigue performance is then quantified, and much lower fatigue lives are measured after ageing. At a higher level, flume tank tests have been performed on three-blade tidal turbines. Strain gauging of blades has provided data to compare with numerical models.

Durability of commercial aircraft and helicopter composite structures

NASA Technical Reports Server (NTRS)

Dexter, H. B.

1982-01-01

The development of advanced composite technology during the past decade is discussed. Both secondary and primary components fabricated with boron, graphite, and Kevlar composites are evaluated. Included are spoilers, rudders, and fairings on commercial transports, boron/epoxy reinforced wing structure on C-130 military transports, and doors, fairings, tail rotors, vertical fins, and horizontal stabilizers on commercial helicopters. The development of composite structures resulted in advances in design and manufacturing technology for secondary and primary composite structures for commercial transports. Design concepts and inspection and maintenance results for the components in service are reported. The flight, outdoor ground, and controlled laboratory environmental effects on composites were also determined. Effects of moisture absorption, ultraviolet radiation, aircraft fuels and fluids, and sustained tensile stress are included. Critical parameters affecting the long term durability of composite materials are identified.

"Insensitive" to touch: fabric-supported lubricant-swollen polymeric films for omniphobic personal protective gear.

PubMed

Damle, Viraj G; Tummala, Abhishiktha; Chandrashekar, Sriram; Kido, Cassidee; Roopesh, Ajay; Sun, Xiaoda; Doudrick, Kyle; Chinn, Jeff; Lee, James R; Burgin, Timothy P; Rykaczewski, Konrad

2015-02-25

The use of personal protective gear made from omniphobic materials that easily shed drops of all sizes could provide enhanced protection from direct exposure to most liquid-phase biological and chemical hazards and facilitate the postexposure decontamination of the gear. In recent literature, lubricated nanostructured fabrics are seen as attractive candidates for personal protective gear due to their omniphobic and self-healing characteristics. However, the ability of these lubricated fabrics to shed low surface tension liquids after physical contact with other objects in the surrounding, which is critical in demanding healthcare and military field operations, has not been investigated. In this work, we investigate the depletion of oil from lubricated fabrics in contact with highly absorbing porous media and the resulting changes in the wetting characteristics of the fabrics by representative low and high surface tension liquids. In particular, we quantify the loss of the lubricant and the dynamic contact angles of water and ethanol on lubricated fabrics upon repeated pressurized contact with highly absorbent cellulose-fiber wipes at different time intervals. We demonstrate that, in contrast to hydrophobic nanoparticle coated microfibers, fabrics encapsulated within a polymer that swells with the lubricant retain the majority of the oil and are capable of repelling high as well as low surface tension liquids even upon multiple contacts with the highly absorbing wipes. The fabric supported lubricant-swollen polymeric films introduced here, therefore, could provide durable and easy to decontaminate protection against hazardous biological and chemical liquids.

A thermoplastic/thermoset blend exhibiting thermal mending and reversible adhesion.

PubMed

Luo, Xiaofan; Ou, Runqing; Eberly, Daniel E; Singhal, Amit; Viratyaporn, Wantinee; Mather, Patrick T

2009-03-01

In this paper, we report on the development of a new and broadly applicable strategy to produce thermally mendable polymeric materials, demonstrated with an epoxy/poly(-caprolactone) (PCL) phase-separated blend. The initially miscible blend composed of 15.5 wt % PCL undergoes polymerization-induced phase separation during cross-linking of the epoxy, yielding a "bricks and mortar" morphology wherein the epoxy phase exists as interconnected spheres (bricks) interpenetrated with a percolating PCL matrix (mortar). The fully cured material is stiff, strong, and durable. A heating-induced "bleeding" behavior was witnessed in the form of spontaneous wetting of all free surfaces by the molten PCL phase, and this bleeding is capable of repairing damage by crack-wicking and subsequent recrystallization with only minor concomitant softening during that process. The observed bleeding is attributed to volumetric thermal expansion of PCL above its melting point in excess of epoxy brick expansion, which we term differential expansive bleeding (DEB). In controlled thermal-mending experiments, heating of a cracked specimen led to PCL extrusion from the bulk to yield a liquid layer bridging the crack gap. Upon cooling, a "scar" composed of PCL crystals formed at the site of the crack, restoring a significant portion of the mechanical strength. When a moderate force was applied to assist crack closure, thermal-mending efficiencies exceeded 100%. We further observed that the DEB phenomenon enables strong and facile adhesion of the same material to itself and to a variety of materials, without any requirement for macroscopic softening or flow.

Floorward thinking.

PubMed Central

Fisher, B E

1999-01-01

From its creation to its disposal, there are environmental and health problems associated with polyvinyl chloride (vinyl), the major component of vinyl flooring. The production of vinyl creates toxic waste that must be dumped or incinerated. Because very little vinyl is recycled, the waste material must also be landfilled or burned. Furthermore, the heavy chlorine content of these materials result in the release of dioxins into the environment. A new flooring alternative to vinyl recently entered the market. Stratica, manufactured by Amtico Company Limited based in Coventry, United Kingdom, is made from polymer resins and offers the durability of vinyl without the environmental impact. PMID:10379015

Floorward thinking.

PubMed

Fisher, B E

1999-07-01

From its creation to its disposal, there are environmental and health problems associated with polyvinyl chloride (vinyl), the major component of vinyl flooring. The production of vinyl creates toxic waste that must be dumped or incinerated. Because very little vinyl is recycled, the waste material must also be landfilled or burned. Furthermore, the heavy chlorine content of these materials result in the release of dioxins into the environment. A new flooring alternative to vinyl recently entered the market. Stratica, manufactured by Amtico Company Limited based in Coventry, United Kingdom, is made from polymer resins and offers the durability of vinyl without the environmental impact.

Methylene Diphenyl Diisocyanate (monomeric MDI) and polymeric MDI (PMDI)

Integrated Risk Information System (IRIS)

TOXICOLOGICAL REVIEW of METHYLENE DIPHENYL DIISOCYANATE ( MDI ) ( CAS No . 101 - 68 - 8 and 9016 - 87 - 9 ) In Support of Summary Information on the Integrated Risk Information System ( IRIS ) February 1998 U.S . ENVIRONMENTAL PROTECTION AGENCY WASHINGTON , DC TABLE OF CONTENTS TOXICOLOGICAL REV

Coating of Carbon Fiber with Polyhedral Oligomeric Silsesquioxane (POSS) to Enhance Mechanical Properties and Durability of Carbon/Vinyl Ester Composites

PubMed Central

Mahfuz, Hassan; Powell, Felicia; Granata, Richard; Hosur, Mahesh; Khan, Mujib

2011-01-01

Our continuing quest to improve the performance of polymer composites under moist and saltwater environments has gained momentum in recent years with the reinforcement of inorganic nanoparticles into the polymer. The key to mitigate degradation of composites under such environments is to maintain the integrity of the fiber/matrix (F/M) interface. In this study, the F/M interface of carbon/vinyl ester composites has been modified by coating the carbon fiber with polyhedral oligomeric silsesquioxane (POSS). POSS is a nanostructured inorganic-organic hybrid particle with a cubic structure having silicon atoms at the core and linked to oxygen atoms. The advantage of using POSS is that the silicon atoms can be linked to a substituent that can be almost any chemical group known in organic chemistry. Cubic silica cores are ‘hard particles’ and are about 0.53 nm in diameter. The peripheral organic unit is a sphere of about 1–3 nm in diameter. Further, cubic structure of POSS remains intact during the polymerization process and therefore with appropriate functional groups, if installed on the fiber surface, would provide a stable and strong F/M interface. Two POSS systems with two different functional groups; namely, octaisobutyl and trisilanolphenyl have been investigated. A set of chemical and mechanical procedures has been developed to coat carbon fibers with POSS, and to fabricate layered composites with vinyl ester resin. Interlaminar shear and low velocity impact tests have indicated around 17–38% improvement in mechanical properties with respect to control samples made without the POSS coating. Saltwater and hygrothermal tests at various environmental conditions have revealed that coating with POSS reduces water absorption by 20–30% and retains the composite properties. PMID:28824160

Advances in stir bar sorptive extraction for the determination of acidic pharmaceuticals in environmental water matrices Comparison between polyurethane and polydimethylsiloxane polymeric phases.

PubMed

Silva, Ana Rita M; Portugal, Fátima C M; Nogueira, J M F

2008-10-31

Stir bar sorptive extraction with polyurethane (PU) and polydimethylsiloxane (PDMS) polymeric phases followed by high-performance liquid chromatography with diode array detection [SBSE(PU or PDMS)/HPLC-DAD] was studied for the determination of six acidic pharmaceuticals [o-acetylsalicylic acid (ACA), ibuprofen (IBU), diclofenac sodium (DIC), naproxen (NAP), mefenamic acid (MEF) and gemfibrozil (GEM)], selected as non-steroidal acidic anti-inflammatory drugs and lipid regulators model compounds in environmental water matrices. The main parameters affecting the efficiency of the proposed methodology are fully discussed. Assays performed on 25 mL of water samples spiked at the 10 microg L(-1) level under optimized experimental conditions, yielded recoveries ranging from 45.3+/-9.0% (ACA) to 90.6+/-7.2% (IBU) by SBSE(PU) and 9.8+/-1.6% (NAP) to 73.4+/-5.0% (GEM) by SBSE(PDMS), where the former polymeric phase presented a better affinity to extract these target analytes from water matrices at the trace level. The methodology showed also excellent linear dynamic ranges for the six acidic pharmaceuticals studied, with correlation coefficients higher than 0.9976, limits of detection and quantification between 0.40-1.7 microg L(-1) and 1.5-5.8 microg L(-1), respectively, and suitable precision (RSD <15%). Moreover, the developed methodology was applied for the determination of these target analytes in several environmental matrices, including river, sea and wastewater samples, having achieved good performance and moderate matrix effects. In short, the PU foams demonstrated to be an excellent alternative for the enrichment of the more polar metabolites from water matrices by SBSE, overcoming the limitations of the conventional PDMS phase.

Advanced Materials by Atom Transfer Radical Polymerization.

PubMed

Matyjaszewski, Krzysztof

2018-06-01

Atom transfer radical polymerization (ATRP) has been successfully employed for the preparation of various advanced materials with controlled architecture. New catalysts with strongly enhanced activity permit more environmentally benign ATRP procedures using ppm levels of catalyst. Precise control over polymer composition, topology, and incorporation of site specific functionality enables synthesis of well-defined gradient, block, comb copolymers, polymers with (hyper)branched structures including stars, densely grafted molecular brushes or networks, as well as inorganic-organic hybrid materials and bioconjugates. Examples of specific applications of functional materials include thermoplastic elastomers, nanostructured carbons, surfactants, dispersants, functionalized surfaces, and biorelated materials. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Facing the rain after the phase out: Performance evaluation of alternative fluorinated and non-fluorinated durable water repellents for outdoor fabrics.

PubMed

Schellenberger, S; Gillgard, P; Stare, A; Hanning, A; Levenstam, O; Roos, S; Cousins, I T

2018-02-01

Fluorinated durable water repellent (DWR) agents are used to obtain water and stain repellent textiles. Due to the on-going phase-out of DWRs based on side-chain fluorinated polymers (SFP) with "long" perfluoroalkyl chains, the textile industry lacks suitable alternatives with comparable material characteristics. The constant development and optimization of SFPs for textile applications initiated more than half a century ago has resulted in a robust and very efficient DWR-technology and textiles with exceptional hydro- and oleo-phobic properties. The industry is now in the predicament that the long-chain SFPs with the best technical performance have undesirable toxicological and environmental behaviour. This study provides a comprehensive overview of the technical performance of presently available fluorinated and non-fluorinated DWRs as part of a chemical alternatives assessment (CAA). The results are based on a study with synthetic outdoor fabrics treated with alternative DWRs and tested for repellency using industrial standard and complementary methods. Using this approach, the complex structure-property relationships of DWR-polymers could be explained on a molecular level. Both short-chain SFPs and non-fluorinated DWRs showed excellent water repellency and durability in some cases while short-chain SFPs were the more robust of the alternatives to long-chain SFPs. A strong decline in oil repellency and durability with perfluoroalkyl chain length was shown for SFP DWRs. Non-fluorinated alternatives were unable to repel oil, which might limit their potential for substitution in textile application that require repellency towards non-polar liquids. Copyright © 2017. Published by Elsevier Ltd.

Molecularly imprinted polymers coated on multi-walled carbon nanotubes through a simple indirect method for the determination of 2,4-dichlorophenoxyacetic acid in environmental water

NASA Astrophysics Data System (ADS)

Yang, Weijie; Jiao, Feipeng; Zhou, Lei; Chen, Xiaoqing; Jiang, Xinyu

2013-11-01

A new and facile method was presented to graft molecularly imprinted polymers (MIPs) on carbon nanotubes (CNTs) for 2,4-dichlorophenoxyacetic acid (2,4-D) analysis. In brief, CNTs were firstly coated with a layer of vinyl group modified silica, followed by a common precipitation polymerization with 2,4-D as the template, ethylene glycol dimethacrylate (EGDMA) as the crosslinker and 2,2-azobisisobutyronitrile (AIBN) as the initiator. The imprinted effects obtained by using different monomers were investigated, and the results showed that acrylamide (AM) and styrene as mixed monomers was the best choice. This functionalized material was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermogravimetry (TG), which demonstrated a successful polymerization reaction on CNTs with MIPs grafting ratio of about 80%. The results of static adsorption experiments indicated the imprinted material possessed fast kinetics and good selectivity for 2,4-D molecules. A corresponding analytical method was developed and demonstrated to be applicable for the determination of 2,4-D in environmental water. The recoveries were in the range from 74.6% to 81.2% with relative standard deviation below 7.0%. To be emphasized, the method for MIPs coating proposed herein also provides a significant reference for other radical polymerization reactions based on CNTs.

Monitoring Sealant Durability during Instrumented Outdoor Exposure with Variation in Prestrain

Treesearch

Gregory T. Schueneman; Steven Lacher; Christopher G. Hunt

2015-01-01

Sealants are a vital part of a building’s environmental barrier envelope. Their ability to bond to numerous dissimilar substrates and form cure-in-place seals results in their widespread use throughout single story and high rise buildings. A typical 40 story concrete and glass facade building can have 70 miles of sealant bonds. Failure of sealants can lead to energy...

Cold Regions - Environmental Testing of Individual Soldier Clothing

DTIC Science & Technology

2011-10-17

Individual Soldier Clothing 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHORS 5d. PROJECT NUMBER 5e. TASK...This Test Operations Procedure (TOP) provides testing guidelines for individual Soldier cold weather clothing and footwear in a cold regions...Soldier clothing , along with its safety, reliability, durability, and performance when exposed to a cold regions environment. 15. SUBJECT TERMS

Anti-graffiti nanocomposite materials for surface protection of a very porous stone

NASA Astrophysics Data System (ADS)

Licchelli, Maurizio; Malagodi, Marco; Weththimuni, Maduka; Zanchi, Chiara

2014-09-01

The preservation of stone substrates from defacement induced by graffiti represents a very challenging task, which can be faced by applying suitable protective agents on the surface. Although different anti-graffiti materials have been developed, it is often found that their effectiveness is unsatisfactory, most of all when applied on very porous stones, e.g. Lecce stone. The aim of this work was to study the anti-graffiti behaviour of new nanocomposite materials obtained by dispersing montmorillonite nanoparticles (layered aluminosilicates with a high-aspect ratio) into a fluorinated polymer matrix (a fluorinated polyurethane based on perfluoropolyether blocks). Polymeric structure was modified by inducing a cross-linking process, in order to produce a durable anti-graffiti coating with enhanced barrier properties. Several composites were prepared using a naturally occurring and an organically modified montmorillonite clay (1, 3, and 5 % w/w concentrations). Materials were applied on Lecce stone specimens, and then their treated surfaces were soiled by a black ink permanent marker or by a black acrylic spray paint. Several repeated staining/cleaning cycles were performed in order to evaluate anti-graffiti effectiveness. Colorimetric measurements were selected to assess the anti-graffiti performance. It was found that the presence of 3 % w/w organically modified montmorillonite in the polymer coating is enough to induce a durable anti-graffiti effect when the stone surface is stained by acrylic paint. Less promising results are obtained when staining by permanent marker is considered as all the investigated treatments afford a reasonable protection from ink only for the first staining/cleaning cycle.

Novel polymeric products derived from biodiesel

USDA-ARS?s Scientific Manuscript database

Biodiesel (produced by reacting a triglyceride with an alcohol) is increasingly being used as diesel fuel and heating oil, especially in Europe. Because of its availability and favorable environmental profile, it may be useful as a renewable feedstock for new polymers. In this work we introduced t...

Polyfunctional epoxies. I - Rubber-toughened brominated and nonbrominated formulations for graphite composites. II - Nonrubber versus rubber-toughened brominated formulations for graphite composites

NASA Technical Reports Server (NTRS)

Nir, Z.; Gilwee, W. J.; Kourtides, D. A.; Parker, J. A.

1985-01-01

A new trifunctional epoxy resin, Tris-(hydroxyphenyl) methane triglycidyl ether, is compared to a state-of-the-art tetraglycidyl 4,4'-diaminodiphenyl methane (TGDDM), in graphite composites. Rubber-toughened brominated formulations of the epoxy resin are compared to nonbrominated ones in terms of their mechanical performance, environmental stability, thermochemical behavior, and flame retardancy. It is shown that the new resin performs almost the same way as the TGDDM does, but has improved glass transition temperature and environmental properties. Brominated polymeric additives (BPA) of different molecular weights are tested as a Br source to flame retardant graphite epoxy composites. The optimal molecular weight of the BPA and its polymeric backbone length are derived and compared with a 10 percent rubber-toughened formulation of the epoxy resin. Results indicate that when the Br content in the graphite composite is increased without the use of rubber, the mechanical properties improved. The use of BPAs as tougheners for graphite composites is also considered.

Use of the SPARC software program to calculate hydrolysis rate constants for the polymeric brominated flame retardants BC-58 and FR-1025.

PubMed

Rayne, Sierra; Forest, Kaya

2016-01-01

The SPARC software program was used to estimate the acid-catalyzed, neutral, and base-catalyzed hydrolysis rate constants for the polymeric brominated flame retardants BC-58 and FR-1025. Relatively rapid hydrolysis of BC-58, producing 2,4,6-tribromophenol-and ultimately tetrabromobisphenol A-as the hydrolytically stable end products from all potential hydrolysis reactions, is expected in both environmental and biological systems with starting material hydrolytic half-lives (t(1/2,hydr)) ranging from less than 1 h in marine systems, several hours in cellular environments, and up to several weeks in slightly acid fresh waters. Hydrolysis of FR-1025 to give 2,3,4,5,6-pentabromobenzyl alcohol is expected to be slower (t(1/2,hydr) less than 0.5 years in marine systems up to several years in fresh waters) than BC-58, but is also expected to occur at rates that will contribute significantly to environmental and in vivo loadings of this compound.

Quantification of water penetration into concrete through cracks by neutron radiography

NASA Astrophysics Data System (ADS)

Kanematsu, M.; Maruyama, I.; Noguchi, T.; Iikura, H.; Tsuchiya, N.

2009-06-01

Improving the durability of concrete structures is one of the ways to contribute to the sustainable development of society, and it has also become a crucial issue from an environmental viewpoint. It is well known that moisture behavior in reinforced concrete is linked to phenomena such as cement hydration, volume change and cracking caused by drying shrinkage, rebar corrosion and water leakage that affect the durability of concrete. In this research, neutron radiography was applied for visualization and quantification of water penetration into concrete through cracks. It is clearly confirmed that TNR can make visible the water behavior in/near horizontal/vertical cracks and can quantify the rate of diffusion and concentration distribution of moisture with high spatial and time resolution. On detailed analysis, it is observed that water penetrates through the crack immediately after pouring and its migration speed and distribution depend on the moisture condition in the concrete.

Cooled optical filters for Q-band infrared astronomy (15-40 μm)

NASA Astrophysics Data System (ADS)

Hawkins, Gary J.; Sherwood, Richard E.; Djotni, Karim; Threadgold, Timothy M.

2016-07-01

With a growing interest in mid- and far-infrared astronomy using cooled imaging and spectrometer instruments in highaltitude observatories and spaceflight telescopes, it is becoming increasingly important to characterise and assess the spectral performance of cooled multilayer filters across the Q-band atmospheric window. This region contains spectral features emitted by many astrophysical phenomena and objects fundamental to circumstellar and planetary formation theories. However extending interference filtering to isolate radiation at progressively longer wavelengths and improve photometric accuracy is an area of ongoing and challenging thin-film research. We have successfully fabricated cooled bandpass and edge filters with high durability for operation across the 15-30 μm Q-band region. In this paper we describe the rationale for selection of optical materials and properties of fabricated thin-film coatings for this region, together with FTIR spectral measurements and assessment of environmental durability.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Narayan, Tarun C.; Hayee, Fariah; Baldi, Andrea

Many energy storage materials undergo large volume changes during charging and discharging. The resulting stresses often lead to defect formation in the bulk, but less so in nanosized systems. Here, we capture in real time the mechanism of one such transformation—the hydrogenation of single-crystalline palladium nanocubes from 15 to 80 nm—to better understand the reason for this durability. First, using environmental scanning transmission electron microscopy, we monitor the hydrogen absorption process in real time with 3 nm resolution. Then, using dark-field imaging, we structurally examine the reaction intermediates with 1 nm resolution. The reaction proceeds through nucleation and growth ofmore » the new phase in corners of the nanocubes. As the hydrogenated phase propagates across the particles, portions of the lattice misorient by 1.5%, diminishing crystal quality. Once transformed, all the particles explored return to a pristine state. As a result, the nanoparticles’ ability to remove crystallographic imperfections renders them more durable than their bulk counterparts.« less

Nanotechnology in Textiles.

PubMed

Yetisen, Ali K; Qu, Hang; Manbachi, Amir; Butt, Haider; Dokmeci, Mehmet R; Hinestroza, Juan P; Skorobogatiy, Maksim; Khademhosseini, Ali; Yun, Seok Hyun

2016-03-22

Increasing customer demand for durable and functional apparel manufactured in a sustainable manner has created an opportunity for nanomaterials to be integrated into textile substrates. Nanomoieties can induce stain repellence, wrinkle-freeness, static elimination, and electrical conductivity to fibers without compromising their comfort and flexibility. Nanomaterials also offer a wider application potential to create connected garments that can sense and respond to external stimuli via electrical, color, or physiological signals. This review discusses electronic and photonic nanotechnologies that are integrated with textiles and shows their applications in displays, sensing, and drug release within the context of performance, durability, and connectivity. Risk factors including nanotoxicity, nanomaterial release during washing, and environmental impact of nanotextiles based on life cycle assessments have been evaluated. This review also provides an analysis of nanotechnology consolidation in the textiles market to evaluate global trends and patent coverage, supplemented by case studies of commercial products. Perceived limitations of nanotechnology in the textile industry and future directions are identified.

Sensitive determination of estrogens in environmental waters treated with polymeric ionic liquid-based stir cake sorptive extraction and liquid chromatographic analysis.

PubMed

Chen, Lei; Mei, Meng; Huang, Xiaojia; Yuan, Dongxing

2016-05-15

A simple, sensitive and environmentally friendly method using polymeric ionic liquid-based stir cake sorptive extraction followed by high performance liquid chromatography with diode array detection (HPLC/DAD) has been developed for efficient quantification of six selected estrogens in environmental waters. To extract trace estrogens effectively, a poly (1-ally-3-vinylimidazolium chloride-co-ethylene dimethacrylate) monolithic cake was prepared and used as the sorbent of stir cake sorptive extraction (SCSE). The effects of preparation conditions of sorbent and extraction parameters of SCSE for estrogens were investigated and optimized. Under optimal conditions, the developed method showed satisfactory analytical performance for targeted analytes. Low limits of detection (S/N=3) and quantification limits (S/N=10) were achieved within the range of 0.024-0.057 µg/L and 0.08-0.19 µg/L, respectively. Good linearity of method was obtained for analytes with the correlation coefficients (R(2)) above 0.99. At the same time, satisfactory method repeatability and reproducibility was achieved in terms of intra- and inter-day precisions, respectively. Finally, the established SCSE-HPLC/DAD method was successfully applied for the determination of estrogens in different environmental water samples. Recoveries obtained for the determination of estrogens in spiked samples ranged from 71.2% to 108%, with RSDs below 10% in all cases. Copyright © 2016 Elsevier B.V. All rights reserved.

Prediction of Adsorption Equilibrium of VOCs onto Hyper-Cross-Linked Polymeric Resin at Environmentally Relevant Temperatures and Concentrations Using Inverse Gas Chromatography.

PubMed

Jia, Lijuan; Ma, Jiakai; Shi, Qiuyi; Long, Chao

2017-01-03

Hyper-cross-linked polymeric resin (HPR) represents a class of predominantly microporous adsorbents and has good adsorption performance toward VOCs. However, adsorption equilibrium of VOCs onto HPR are limited. In this research, a novel method for predicting adsorption capacities of VOCs on HPR at environmentally relevant temperatures and concentrations using inverse gas chromatography data was proposed. Adsorption equilibrium of six VOCs (n-pentane, n-hexane, dichloromethane, acetone, benzene, 1, 2-dichloroethane) onto HPR in the temperature range of 403-443 K were measured by inverse gas chromatography (IGC). Adsorption capacities at environmentally relevant temperatures (293-328 K) and concentrations (P/P s = 0.1-0.7) were predicted using Dubinin-Radushkevich (DR) equation based on Polany's theory. Taking consideration of the swelling properties of HPR, the volume swelling ratio (r) was introduced and r·V micro was used instead of V micro determined by N 2 adsorption data at 77 K as the parameter q 0 (limiting micropore volume) of the DR equation. The results showed that the adsorption capacities of VOCs at environmentally relevant temperatures and concentrations can be predicted effectively using IGC data, the root-mean-square errors between the predicted and experimental data was below 9.63%. The results are meaningful because they allow accurate prediction of adsorption capacities of adsorbents more quickly and conveniently using IGC data.

The Influence of Sizings on the Durability of High-Temperature Polymer Composites

NASA Technical Reports Server (NTRS)

Allred, Ronald E.; Wesson, Sheldon P.; Shin, E. Eugene; Inghram, Linda; McCorkle, Linda; Papadopoulos, Demetrios; Wheeler, Donald; Sutter, James K.

2004-01-01

To increase performance and durability of high-temperature composites for potential rocket engine components, it is necessary to optimize wetting and interfacial bonding between high modulus carbon fibers and high-temperature polyimide resins. Sizings commercially supplied on most carbon fibers are not compatible with polyimides. In this study, the chemistry of sizings on two high-modulus carbon fibers (M40J and M60J, Toray) was characterized as was the chemistry of PMR-II-50 fluorinated polyimide resin. The carbon fibers were characterized using single filament wetting, scanning electron microscopy, fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopic measurements. The polyimide matrix resins were coated onto glass filaments for characterization by wetting measurements. Surface energy components were obtained by wetting with nondispersive (methylene iodide), acidic (ethylene glycol), and basic (formamide) probes. A continuous desizing system that uses an environmentally friendly chemical-mechanical process was developed for tow level fiber. Composites were fabricated with fibers containing the manufacturer's sizing, desized, and further treated with a reactive finish. Results of room-temperature tests after thermal aging show that the reactive finish produces a higher strength and more durable interface compared to the manufacturer's sizing. When exposed to moisture blistering tests, however, the better bonded composite displayed a tendency to delaminate, presumably due to trapping of volatiles.

Localized heating/bonding techniques in MEMS packaging

NASA Astrophysics Data System (ADS)

Mabesa, J. R., Jr.; Scott, A. J.; Wu, X.; Auner, G. W.

2005-05-01

Packaging is used to protect and enable intelligent sensor systems utilized in manned/unmanned ground vehicle systems/subsystems. Because Micro electro mechanical systems (MEMS) are used often in these sensor or actuation products, it must interact with the surrounding environment, which may be in direct conflict with the desire to isolate the electronics for improved reliability/durability performance. For some very simple devices, performance requirements may allow a high degree of isolation from the environment (e.g., stints and accelerometers). Other more complex devices (i.e. chemical and biological analysis systems, particularly in vivo systems) present extremely complex packaging requirements. Power and communications to MEMS device arrays are also extremely problematic. The following describes the research being performed at the U.S. Army Research, Development, and Engineering Command (RDECOM) Tank and Automotive Research, Development, and Engineering Center (TARDEC), in collaboration with Wayne State University, in Detroit, MI. The focus of the packaging research is limited to six main categories: a) provision for feed-through for electrical, optical, thermal, and fluidic interfaces; b) environmental management including atmosphere, hermiticity, and temperature; c) control of stress and mechanical durability; d) management of thermal properties to minimize absorption and/or emission; e) durability and structural integrity; and f) management of RF/magnetic/electrical and optical interference and/or radiation properties and exposure.

Thin film polymeric gel electrolytes

DOEpatents

Derzon, Dora K.; Arnold, Jr., Charles; Delnick, Frank M.

1996-01-01

Novel hybrid thin film electrolyte, based on an organonitrile solvent system, which are compositionally stable, environmentally safe, can be produced efficiently in large quantity and which, because of their high conductivities .apprxeq.10.sup.-3 .OMEGA..sup.-1 cm.sup.-1 are useful as electrolytes for rechargeable lithium batteries.

Adsorption of environmental pollutants using magnetic hybrid nanoparticles modified with β-cyclodextrin

NASA Astrophysics Data System (ADS)

Wang, Niejun; Zhou, Lilin; Guo, Jun; Ye, Qiquan; Lin, Jin-Ming; Yuan, Jinying

2014-06-01

Graft through strategy was utilized to coat magnetic Fe3O4 nanoparticles with poly(glycidyl methacrylate) using ordinary radical polymerization and then β-cyclodextrin was linked onto the surface of nanoparticles. With these nanoparticles modified with cyclodextrin groups, adsorption of two model environmental pollutants, bisphenol A and copper ions, was studied. Host-guest interactions between cyclodextrin and aromatic molecules had a great contribution to the adsorption of bisphenol A, while multiple hydroxyls of cyclodextrin also helped the adsorption of copper ions. These magnetic nanoparticles could be applied in the elimination, enrichment and detection of some environmental pollutants.

Advanced Thermal Barrier and Environmental Barrier Coating Development at NASA GRC

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Robinson, Craig

2017-01-01

This presentation summarizes NASA's advanced thermal barrier and environmental barrier coating systems, and the coating performance improvements that has recently been achieved and documented in laboratory simulated rig test conditions. One of the emphases has been placed on the toughness and impact resistance enhancements of the low conductivity, defect cluster thermal barrier coating systems. The advances in the next generation environmental barrier coatings for SiCSiC ceramic matrix composites have also been highlighted, particularly in the design of a new series of oxide-silicate composition systems to be integrated with next generation SiC-SiC turbine engine components for 2700F coating applications. Major technical barriers in developing the thermal and environmental barrier coating systems are also described. The performance and model validations in the rig simulated turbine combustion, heat flux, steam and calcium-magnesium-aluminosilicate (CMAS) environments have helped the current progress in improved temperature capability, environmental stability, and long-term fatigue-environment system durability of the advanced thermal and environmental barrier coating systems.

Performance and Durability Assessment of Two Emission Control Technologies Installed on a Legacy High-Speed Marine Diesel Engine

DTIC Science & Technology

2015-11-05

program investigated cost- effective technologies to reduce emissions from legacy marine engines. High-speed, high-population engine models in both...respectively) were driven by health effects and environmental impacts. The U.S. Navy assessed its contribution to the domestic marine emission inventory...greatest potential. A laboratory developmental assessment was followed by a shipboard evaluation. Effective technology concepts applied to high

Newly Elaborated Multipurpose Polymer Electrolyte Encompassing RTILs for Smart Energy-Efficient Devices.

PubMed

Nair, Jijeesh R; Porcarelli, Luca; Bella, Federico; Gerbaldi, Claudio

2015-06-17

Profoundly ion-conducting, self-standing, and tack-free ethylene oxide-based polymer electrolytes encompassing a room-temperature ionic liquid (RTIL) with specific amounts of lithium salt are successfully prepared via a rapid and easily upscalable process including a UV irradiation step. All prepared materials are thoroughly characterized in terms of their physical, chemical, and morphological properties and eventually galvanostatically cycled in lab-scale lithium batteries (LIBs) exploiting a novel direct polymerization procedure to get intimate electrode/electrolyte interfacial characteristics. The promising multipurpose characteristics of the newly elaborated materials are demonstrated by testing them in dye-sensitized solar cells (DSSCs), where the introduction of the iodine/iodide-based redox mediator in the polymer matrix assured the functioning of a lab-scale test cell with conversion efficiency exceeding 6% at 1 sun. The reported results enlighten the promising prospects of the material to be successfully implemented as stable, durable, and efficient electrolyte in next-generation energy conversion and storage devices.

Physio-Microstructural Properties of Aerated Cement Slurry for Lightweight Structures

PubMed Central

Salem, Talal; Hamadna, Sameer; Darsanasiri, A. G. N. D.; Soroushian, Parviz; Balchandra, Anagi; Al-Chaar, Ghassan

2018-01-01

Cementitious composites, including ferrocement and continuous fiber reinforced cement, are increasingly considered for building construction and repair. One alternative in processing of these composites is to infiltrate the reinforcement (continuous fibers or chicken mesh) with a flowable cementitious slurry. The relatively high density of cementitious binders, when compared with polymeric binders, are a setback in efforts to introduce cementitious composites as lower-cost, fire-resistant, and durable alternatives to polymer composites. Aeration of the slurry is an effective means of reducing the density of cementitious composites. This approach, however, compromises the mechanical properties of cementitious binders. An experimental program was undertaken in order to assess the potential for production of aerated slurry with a desired balance of density, mechanical performance, and barrier qualities. The potential for nondestructive monitoring of strength development in aerated cementitious slurry was also investigated. This research produced aerated slurries with densities as low as 0.9 g/cm3 with viable mechanical and barrier qualities for production of composites. The microstructure of these composites was also investigated. PMID:29649163

Pt-free carbon-based fuel cell catalyst prepared from spherical polyimide for enhanced oxygen diffusion

PubMed Central

Nabae, Yuta; Nagata, Shinsuke; Hayakawa, Teruaki; Niwa, Hideharu; Harada, Yoshihisa; Oshima, Masaharu; Isoda, Ayano; Matsunaga, Atsushi; Tanaka, Kazuhisa; Aoki, Tsutomu

2016-01-01

The development of a non-precious metal (NPM) fuel cell catalyst is extremely important to achieve globalization of polymer electrolyte fuel cells due to the cost and scarcity of platinum. Here, we report on a NPM cathode catalyst prepared by the pyrolysis of spherical polyimide nanoparticles that contain small amounts of Fe additive. 60 nm diameter Fe-containing polyimide nanoparticles were successfully synthesized by the precipitation polymerization of pyromellitic acid dianhydride and 1,3,5-tris(4-aminophenyl)benzene with Fe(acac)3 (acac = acetylacetonate) as an additive. The particles were subsequently carbonized by multistep pyrolysis to obtain the NPM catalyst while retaining the small particle size. The catalyst has good performance and promising durability for fuel cell applications. The fuel cell performance under a 0.2 MPa air atmosphere at 80 °C of 1.0 A cm−2 at 0.46 V is especially remarkable and better than that previously reported. PMID:26987682

Undercutting of defects in thin film protective coatings on polymer surfaces exposed to atomic oxygen

NASA Technical Reports Server (NTRS)

Rutledge, Sharon K.; Mihelcic, Judith A.

1989-01-01

Protection for polymeric surfaces is needed to make them durable in the low Earth orbital environment, where oxidation by atomic oxygen is the predominant failure mechanism. Thin film coatings of oxides such as silicon dioxide are viable candidates to provide this protection, but concern has been voiced over the ability of these coatings to protect when defects are present in the coating due to surface anomalies occurring during the deposition process, handling, or micrometeoroid and debris bombardment in low Earth orbit. When a defected coating protecting a polymer substrate is exposed to atomic oxygen, the defect provides a pathway to the underlying polymer allowing oxidation and subsequent undercutting to occur. Defect undercutting was studied for sputter deposited coatings of silicon dioxide on polyimide Kapton. Preliminary results indicate that undercutting may be limited as long as the coating remains intact with the substrate. Therefore, coatings may not need to be defect free to give protection to the underlying surface.

Effect of fluorinated groups on photooxidative stability of polymeric protectives applied on marble.

PubMed

Chiantore, O; Poli, T; Colombo, C; Peruzzi, R; Toniolo, L

2001-01-01

Some new protective copolymers and a commercial one have been tested on Candoglia marble, a very low porosity stone. Two of the polymers contained a partially fluorinated methacrylic monomer, 2,2,2 trifluoro ethyl methacrylate (TFEMA), in combination with either an acrylic, methyl acrylate (MA) or a vinyl ether, n-butyl vinyl ether (n-BVE) unit. Two copolymers, ethyl methacrylate/n-butyl vinyl ether and ethyl methacrylate (EMA)/methyl acrylate (Paraloid B72), were non-fluorinated and similar in compositions and molar ratio. The aim of the work is to test the copolymers and compare the performances of fluorinated new polymers with the non fluorinated one and with the largely used commercial product. The results obtained demonstrate that the introduction, even in limited amounts, of fluorine atoms in the side ester groups of methacrylic type polymers really improves their protective effect and the durability of the stone treatments. The best results were obtained with the copolymer TFEM/MA which is the fluorinated homologous of Paraloid B72.

Physio-Microstructural Properties of Aerated Cement Slurry for Lightweight Structures.

PubMed

Almalkawi, Areej T; Salem, Talal; Hamadna, Sameer; Darsanasiri, A G N D; Soroushian, Parviz; Balchandra, Anagi; Al-Chaar, Ghassan

2018-04-12

Cementitious composites, including ferrocement and continuous fiber reinforced cement, are increasingly considered for building construction and repair. One alternative in processing of these composites is to infiltrate the reinforcement (continuous fibers or chicken mesh) with a flowable cementitious slurry. The relatively high density of cementitious binders, when compared with polymeric binders, are a setback in efforts to introduce cementitious composites as lower-cost, fire-resistant, and durable alternatives to polymer composites. Aeration of the slurry is an effective means of reducing the density of cementitious composites. This approach, however, compromises the mechanical properties of cementitious binders. An experimental program was undertaken in order to assess the potential for production of aerated slurry with a desired balance of density, mechanical performance, and barrier qualities. The potential for nondestructive monitoring of strength development in aerated cementitious slurry was also investigated. This research produced aerated slurries with densities as low as 0.9 g/cm³ with viable mechanical and barrier qualities for production of composites. The microstructure of these composites was also investigated.

Nano-Charged Polypropylene Application: Realistic Perspectives for Enhancing Durability

PubMed Central

Naddeo, Carlo; Vertuccio, Luigi; Barra, Giuseppina; Guadagno, Liberata

2017-01-01

Isotactic polypropylene/multi-walled carbon nanotube (iPP/MWCNTs) films have been exposed to accelerated weathering in a UV device for increasing times. The effect of UV irradiation on the structural and chemical changes has been investigated. The resistance to accelerated photooxidation of (iPP/MWCNTs) films has been compared to the photooxidation behaviour of unfilled polypropylene films with the same structural organization. The chemical and structural modifications resulting from photooxidation have been followed using infrared spectroscopy, calorimetric and diffractometric analysis. MWCNTs embedded in the polymeric matrix are able to strongly contrast the degradation mechanisms and the structural and morphological rearrangements caused by the UV treatment on the unfilled polymer. MWCNTs determine an induction period (IP) before the increase of the carbonyl and hydroxyl groups. The extent of the IP is strictly correlated to the amount of MWCNTs. The low electrical percolation threshold (EPT) and the electrical conductivity of the nanocomposites, together with their excellent thermal and photooxidative stability, make them promising candidates to fulfill many industrial requirements. PMID:28805728

Advanced Separators for Lithium-Ion and Lithium-Sulfur Batteries: A Review of Recent Progress.

PubMed

Xiang, Yinyu; Li, Junsheng; Lei, Jiaheng; Liu, Dan; Xie, Zhizhong; Qu, Deyu; Li, Ke; Deng, Tengfei; Tang, Haolin

2016-11-09

Li-ion and Li-S batteries find enormous applications in different fields, such as electric vehicles and portable electronics. A separator is an indispensable part of the battery design, which functions as a physical barrier for the electrode as well as an electrolyte reservoir for ionic transport. The properties of the separators directly influence the performance of the batteries. Traditional polyolefin separators showed low thermal stability, poor wettability toward the electrolyte, and inadequate barrier properties to polysulfides. To improve the performance and durability of Li-ion and Li-S batteries, development of advanced separators is required. In this review, we summarize recent progress on the fabrication and application of novel separators, including the functionalized polyolefin separator, polymeric separator, and ceramic separator, for Li-ion and Li-S batteries. The characteristics, advantages, and limitations of these separators are discussed. A brief outlook for the future directions of the research in the separators is also provided. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ensuring repeatability and robustness of poly(glycidyl methacrylate-co-ethylene dimethacrylate) HPLC monolithic columns of 3 mm id through covalent bonding to the column wall.

PubMed

Laaniste, Asko; Kruve, Anneli; Leito, Ivo

2013-08-01

Two different methods to reinforce the poly(glycidyl methacrylate-co-ethylene dimethacrylate) HPLC monolithic columns of 3 mm id in a glass column reservoir were studied: composite columns with polymeric particles in the monolith and surface treatment of the reservoir wall. Of the two methods used to counter the mechanical instability and formation of flow channels (composite columns and column wall surface treatment), we demonstrated that proper column wall surface treatment was sufficient to solve both problems. Our study also indicated that no surface treatment is efficient, and of the methods studied silanization in acidified ethanol solution and constant renewal of the reaction mixture (dynamic mode) proved to be the most effective. As a result of this study, we have been able to prepare repeatable and durable methacrylate HPLC columns with good efficiencies. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Extended Life PZT Stack Test Fixture

NASA Technical Reports Server (NTRS)

Badescu, Mircea; Sherrit, S.; Bao, X.; Aldrich, J.; Bar-Cohen, Y.; Jones, C.

2009-01-01

Piezoelectric stacks are being sought to be used as actuators for precision positioning and deployment of mechanisms in future planetary missions. Beside the requirement for very high operation reliability, these actuators are required for operation at space environments that are considered harsh compared to normal terrestrial conditions.These environmental conditions include low and high temperatures and vacuum or high pressure. Additionally, the stacks are subjected to high stress and in some applications need to operate with a very long lifetime durability.Many of these requirements are beyond the current industry design margins for nominal terrestrial applications. In order to investigate some of the properties that will indicate the durability of such actuators and their limitations we have developed a new type of test fixture that can be easily integrated in various test chambers for simulating environmental conditions, can provide access for multiple measurements while being exposed to adjustable stress levels. We designed and built two test fixtures and these fixtures were made to be adjustable for testing stacks with different dimensions and can be easily used in small or large numbers. The properties that were measured using these fixtures include impedance, capacitance, dielectric loss factor, leakage current, displacement, breakdown voltage, and lifetime performance. The fixtures characteristics and the test capabilities are presented in this paper.

Ionothermal Synthesis of Triazine-Heptazine Based Co-frameworks with Apparent Quantum Yields of 60 % at 420 nm for Solar Hydrogen Production from "Sea Water".

PubMed

Zhang, Guigang; Lin, Lihua; Li, Guosheng; Zhang, Yongfan; Savateev, Aleksandr; Wang, Xinchen; Antonietti, Markus

2018-05-31

Polymeric carbon nitride (PCN), either in triazine or heptazine forms, has been regarded as promising metal-free, environmental benign and sustainable photocatalysts for solar hydrogen production. However, PCN in most cases only exhibits moderate activities due to the inherent properties such as rapid charge carrier recombination. Here we present a triazine-heptazine copolymer synthesized from simple post-calcination of PCN in eutectic salts, i.e. NaCl/KCl, to modulate the polymerization process and optimize the structure. The construction of internal triazine-heptazine donor-acceptor (D-A) heterostructures is affirmed to significantly accelerate the charge transfer (CT) and thus corporately boost the photocatalytic activity (AQY= 60 % at 420 nm). This study highlights the construction of intermolecular D-A copolymers in NaCl/KCl molten salts with higher melting points but absence of lithium to modulate the polymerization process and chemical structure of PCN. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Amphiphilic polymeric micelle as pseudostationary phase in electrokinetic chromatography for analysis of eight corticosteroids in cosmetics.

PubMed

Xu, Xiaojin; Ni, Xinjiong; Cao, Yuhua; Zhuo, Xiaolu; Yang, Xiaoxiao; Cao, Guangqun

2014-03-01

Amphiphilic polymeric micelle, as a novel pseudostationary phase in EKC was used to determine eight kinds of corticosteroids namely hydrocortisone, prednisolone, hydrocortisone acetate, prednisone, cortisone acetate, prednisolone acetate, dexamethasone, and triamcinolone acetonide in cosmetics. Amphiphilic random copolymer poly(methyl methacrylate-co-methacrylic acid) (P(MMA-co-MAA)) was micellizated via neutralization in alkaline aqueous solution. The influences of the molar ratio of monomer MMA to MAA, the concentration of polymer and pH on the polymeric micelle microstructure and EKC performances were investigated. As molar ratio of MMA to MAA in P(MMA-co-MAA) increased, both CMC and environmental polarity of the inner core in polymeric micelle decreased dramatically. With increasing monomer ratio, the size of polymeric micelles increased firstly, and then decreased, finally increased again. ζ potential of the micelle had a slight decline trend. As increment of polymer concentration, the size of the polymeric micelle increased steadily. By optimizing the monomer ratio, the polymer concentration, and pH of the running buffer, as well as operation conditions such as separation voltage and temperature, the eight analytes could be separated within 16.5 min using 7.5 mg/mL polymer with the monomer ratio of 7:3 dissolved in pH 9.2 borax buffer as the running buffer. The method has been used for analysis of corticosteroids in cosmetic samples with simple extraction; the recoveries for eight analytes were between 85.9 and 106%. This method was of accuracy, repeatability, pretreatment simplicity, and could be applied to the quality control of cosmetics. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of polymeric gene delivery nanoparticles by nanoparticle tracking analysis and high-throughput flow cytometry.

PubMed

Shmueli, Ron B; Bhise, Nupura S; Green, Jordan J

2013-03-01

Non-viral gene delivery using polymeric nanoparticles has emerged as an attractive approach for gene therapy to treat genetic diseases(1) and as a technology for regenerative medicine(2). Unlike viruses, which have significant safety issues, polymeric nanoparticles can be designed to be non-toxic, non-immunogenic, non-mutagenic, easier to synthesize, chemically versatile, capable of carrying larger nucleic acid cargo and biodegradable and/or environmentally responsive. Cationic polymers self-assemble with negatively charged DNA via electrostatic interaction to form complexes on the order of 100 nm that are commonly termed polymeric nanoparticles. Examples of biomaterials used to form nanoscale polycationic gene delivery nanoparticles include polylysine, polyphosphoesters, poly(amidoamines)s and polyethylenimine (PEI), which is a non-degradable off-the-shelf cationic polymer commonly used for nucleic acid delivery(1,3) . Poly(beta-amino ester)s (PBAEs) are a newer class of cationic polymers(4) that are hydrolytically degradable(5,6) and have been shown to be effective at gene delivery to hard-to-transfect cell types such as human retinal endothelial cells (HRECs)(7), mouse mammary epithelial cells(8), human brain cancer cells(9) and macrovascular (human umbilical vein, HUVECs) endothelial cells(10). A new protocol to characterize polymeric nanoparticles utilizing nanoparticle tracking analysis (NTA) is described. In this approach, both the particle size distribution and the distribution of the number of plasmids per particle are obtained(11). In addition, a high-throughput 96-well plate transfection assay for rapid screening of the transfection efficacy of polymeric nanoparticles is presented. In this protocol, poly(beta-amino ester)s (PBAEs) are used as model polymers and human retinal endothelial cells (HRECs) are used as model human cells. This protocol can be easily adapted to evaluate any polymeric nanoparticle and any cell type of interest in a multi-well plate format.

Dissolved Divalent Metal and pH Effects on Amino Acid Polymerization: A Thermodynamic Evaluation.

PubMed

Kitadai, Norio

2017-03-01

Polymerization of amino acids is a fundamentally important step for the chemical evolution of life. Nevertheless, its response to changing environmental conditions has not yet been well understood because of the lack of reliable quantitative information. For thermodynamics, detailed prediction over diverse combinations of temperature and pH has been made only for a few amino acid-peptide systems. This study used recently reported thermodynamic dataset for the polymerization of the simplest amino acid "glycine (Gly)" to its short peptides (di-glycine and tri-glycine) to examine chemical and structural characteristics of amino acids and peptides that control the temperature and pH dependence of polymerization. Results showed that the dependency is strongly controlled by the intramolecular distance between the amino and carboxyl groups in an amino acid structure, although the side-chain group role is minor. The polymerization behavior of Gly reported earlier in the literature is therefore expected to be a typical feature for those of α-amino acids. Equilibrium calculations were conducted to examine effects of dissolved metals as a function of pH on the monomer-polymer equilibria of Gly. Results showed that metals shift the equilibria toward the monomer side, particularly at neutral and alkaline pH. Metals that form weak interaction with Gly (e.g., Mg 2+ ) have no noticeable influence on the polymerization, although strong interaction engenders significant decrease of the equilibrium concentrations of Gly peptides. Considering chemical and structural characteristics of Gly and Gly peptides that control their interactions with metals, it can be expected that similar responses to the addition of metals are applicable in the polymerization of neutral α-amino acids. Neutral and alkaline aqueous environments with dissolved metals having high affinity with neutral α-amino acids (e.g., Cu 2+ ) are therefore not beneficial places for peptide bond formation on the primitive Earth.

CMC Technology Advancements for Gas Turbine Engine Applications

NASA Technical Reports Server (NTRS)

Grady, Joseph E.

2013-01-01

CMC research at NASA Glenn is focused on aircraft propulsion applications. The objective is to enable reduced engine emissions and fuel consumption for more environmentally friendly aircraft. Engine system studies show that incorporation of ceramic composites into turbine engines will enable significant reductions in emissions and fuel burn due to increased engine efficiency resulting from reduced cooling requirements for hot section components. This presentation will describe recent progress and challenges in developing fiber and matrix constituents for 2700 F CMC turbine applications. In addition, ongoing research in the development of durable environmental barrier coatings, ceramic joining integration technologies and life prediction methods for CMC engine components will be reviewed.

Switching from Controlled Ring-Opening Polymerization (cROP) to Controlled Ring-Closing Depolymerization (cRCDP) by Adjusting the Reaction Parameters That Determine the Ceiling Temperature

PubMed Central

2016-01-01

Full control over the ceiling temperature (Tc) enables a selective transition between the monomeric and polymeric state. This is exemplified by the conversion of the monomer 2-allyloxymethyl-2-ethyl-trimethylene carbonate (AOMEC) to poly(AOMEC) and back to AOMEC within 10 h by controlling the reaction from conditions that favor ring-opening polymerization (Tc > T0) (where T0 is the reaction temperature) to conditions that favor ring-closing depolymerization (Tc < T0). The ring-closing depolymerization (RCDP) mirrors the polymerization behavior with a clear relation between the monomer concentration and the molecular weight of the polymer, indicating that RCDP occurs at the chain end. The Tc of the polymerization system is highly dependent on the nature of the solvent, for example, in toluene, the Tc of AOMEC is 234 °C and in acetonitrile Tc = 142 °C at the same initial monomer concentration of 2 M. The control over the monomer to polymer equilibrium sets new standards for the selective degradation of polymers, the controlled release of active components, monomer synthesis and material recycling. In particular, the knowledge of the monomer to polymer equilibrium of polymers in solution under selected environmental conditions is of paramount importance for in vivo applications, where the polymer chain is subjected to both high dilution and a high polarity medium in the presence of catalysts, that is, very different conditions from which the polymer was formed. PMID:27783494

Modeling the chemistry of plasma polymerization using mass spectrometry.

PubMed

Ihrig, D F; Stockhaus, J; Scheide, F; Winkelhake, Oliver; Streuber, Oliver

2003-04-01

The goal of the project is a solvent free painting shop. The environmental technologies laboratory is developing processes of plasma etching and polymerization. Polymerized thin films are first-order corrosion protection and primer for painting. Using pure acetylene we get very nice thin films which were not bonded very well. By using air as bulk gas it is possible to polymerize, in an acetylene plasma, well bonded thin films which are stable first-order corrosion protections and good primers. UV/Vis spectroscopy shows nitrogen oxide radicals in the emission spectra of pure nitrogen and air. But nitrogen oxide is fully suppressed in the presence of acetylene. IR spectroscopy shows only C=O, CH(2) and CH(3) groups but no nitrogen species. With the aid of UV/Vis spectra and the chemistry of ozone formation it is possible to define reactive traps and steps, molecule depletion and processes of proton scavenging and proton loss. Using a numerical model it is possible to evaluate these processes and to calculate theoretical mass spectra. Adjustment of theoretical mass spectra to real measurements leads to specific channels of polymerization which are driven by radicals especially the acetyl radical. The estimated theoretical mass spectra show the specific channels of these chemical processes. It is possible to quantify these channels. This quantification represents the mass flow through this chemical system. With respect to these chemical processes it is possible to have an idea of pollutant production processes.

A new type of polymeric heavy metal complexing precipitant used as fishery disinfectant and antiparasitic drug

NASA Astrophysics Data System (ADS)

Liu, Y. C.; Zhang, A. N.; Wang, X. B.; Xu, J.; Zeng, X. H.; Wang, H. M.

2017-08-01

This paper presents a technique to produce a new kind of fishery drug that is water emulsion suspending agent containing polymeric calcium-iron-dithiocarbamate with heavy metal complexing precipitate ability, good disinfection and auxiliary insecticidal efficacy. The product has good dispersion, high efficiency and low toxicity, as well as no pollution and no harmful residues. It not only can be used in the pond waters and ornamental waters, but also can meet the high requirements of the aquaculture waters. There is non-pollutant emission in the production, which is a green environment-friendly technique without three waste discharges. This technology belongs to the ecological and environmental protection.

Towards Self-Replicating Chemical Systems Based on Cytidylic and Guanylic Acids

NASA Technical Reports Server (NTRS)

Kanavarioti, Anastassia

1999-01-01

This project was aimed towards a better understanding of template-directed reactions and, based on this, towards the development of efficient non-enzymatic RNA replicating systems. These systems could serve as models for the prebiotic synthesis of an RNA world. The major objectives of this project are: (a) To elucidate the mechanistic aspects of template-directed (TD) chemistry and (b) to identify active boundary regions, or conditions, environmental and other, that favor "organized chemistry" and stereo-selective polymerization of nucleotides. "Organized chemistry" may lead to enhanced polymerization efficiency which in turn is expected to facilitate the road towards a self-replicating chemical system based on all four nucleic acid bases.

Method of preparing thin film polymeric gel electrolytes

DOEpatents

Derzon, Dora K.; Arnold, Jr., Charles

1997-01-01

Novel hybrid thin film electrolyte, based on an organonitrile solvent system, which are compositionally stable, environmentally safe, can be produced efficiently in large quantity and which, because of their high conductivities .apprxeq.10.sup.-3 .OMEGA..sup.-1 cm.sup.-1 are useful as electrolytes for rechargeable lithium batteries.

Environmental isolation task

NASA Technical Reports Server (NTRS)

Coulbert, C. D.

1982-01-01

The failure-analysis process was organized into a more specific set of long-term degradation steps so that material property change can be differentiated from module damage and module failure. Increasing module performance and life are discussed. A polymeric aging computer model is discussed. Early detection of polymer surface reactions due to aging is reported.

Conformational analysis investigation into the influence of nano-porosity of ultra-permeable ultra-selective polyimides on its diffusivity as potential membranes for use in the "green" separation of natural gases

NASA Astrophysics Data System (ADS)

Madkour, Tarek M.

2013-08-01

Nano-porous polymers of intrinsic microporosity, PIM, have exhibited excellent permeability and selectivity characteristics that could be utilized in an environmentally friendly gas separation process. A full understanding of the mechanism through which these membranes effectively and selectively allow for the permeation of specific gases will lead to further development of these membranes. Three factors obviously influenced the conformational behavior of these polymers, which are the presence of electronegative atoms, the presence of non-linearity in the polymeric backbones (backbone kinks) and the presence of bulky side groups on the polymeric chains. The dipole moment increased sharply with the presence of backbone kinks more than any other factor. Replacing the fluorine atoms with bulky alkyl groups didn't influence the dipole moment greatly indicating that the size of the side chains had much less dramatic influence on the dipole moment than having a bent backbone. Similarly, the presence of the backbone kinks in the polymeric chains influenced the polymeric chains to assume less extended configuration causing the torsional angles around the interconnecting bonds unable to cross the high potential energy barriers. The presence of the bulky side groups also caused the energy barriers of the cis-configurations to increase dramatically, which prevented the polymeric segments from experiencing full rotation about the connecting bonds. For these polymers, it was clear that the fully extended configurations are the preferred configurations in the absence of strong electronegative atoms, backbones kinks or bulky side groups. The addition of any of these factors to the polymeric structures resulted in the polymeric chains being forced to assume less extended configurations. Rather interestingly, the length or bulkiness of the side groups didn't affect the end-to-end distance distribution to a great deal since the presence of quite large bulky side chain such as the pentyl group has caused the polymeric chains to revert back to the fully extended configurations possibly due to the quite high potential energy barriers that the chains have to cross to reach the less extended configurational states.

Evaluation and prediction of long-term environmental effects on non metallic materials

NASA Technical Reports Server (NTRS)

Papazian, H.

1985-01-01

Predictive modeling of environmental conditions on nonmetallic materials was studied. The in-flight data of the atomic oxygen reaction with carbon and osmium, the laboratory and in-flight data of the atomic oxygen reaction with polymeric films and the effect of electron irradiation on the rates of oxidation are discussed. No information is found that can be used to model such effects on composites. The effects of the space environment on thermal control coatings and its effect on the space station are examined.

Transferable Durability: Enhancing decay resistance of non-durable species with extractives from durable wood species

Treesearch

G.T. Kirker; A.B. Blodgett; S. Lebow; C.A. Clausen

2013-01-01

Extractive content and composition is a vital component of naturally durable woods; however, variability in extractives can limit their usefulness in the field. Two extractive-free, non-durable wood species were pressure treated with ethanol-toluene extractives from 8 durable wood species. Extracted Southern pine, Paulownia and unextracted Southern pine blocks were...

Synthesis and Characterization of Microencapsulated Phase Change Materials with Poly(urea-urethane) Shells Containing Cellulose Nanocrystals.

PubMed

Yoo, Youngman; Martinez, Carlos; Youngblood, Jeffrey P

2017-09-20

The main objective of this study is to develop microencapsulation technology for thermal energy storage incorporating a phase change material (PCM) in a composite wall shell, which can be used to create a stable environment and allow the PCM to undergo phase change without any outside influence. Surface modification of cellulose nanocrystals (CNCs) was conducted by grafting poly(lactic acid) oligomers and oleic acid to improve the dispersion of nanoparticles in a polymeric shell. A microencapsulated phase change material (methyl laurate) with poly(urea-urethane) (PU) composite shells containing the hydrophobized cellulose nanocrystals (hCNCs) was fabricated using an in situ emulsion interfacial polymerization process. The encapsulation process of the PCMs with subsequent interfacial hCNC-PU to form composite microcapsules as well as their morphology, composition, thermal properties, and release rates was examined in this study. Oil soluble Sudan II dye solution in methyl laurate was used as a model hydrophobic fill, representing other latent fills with low partition coefficients, and their encapsulation efficiency as well as dye release rates were measured spectroscopically in a water medium. The influence of polyol content in the PU polymer matrix of microcapsules was investigated. An increase in polyol contents leads to an increase in the mean size of microcapsules but a decrease in the gel content (degree of cross-linking density) and permeability of their shell structure. The encapsulated PCMs for thermal energy storage demonstrated here exhibited promising performance for possible use in building or paving materials in terms of released heat, desired phase transformation temperature, chemical and physical stability, and concrete durability during placement.

Phase Stability and Thermal Conductivity of Composite Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Benkel, Samantha; Zhu, Dongming

2011-01-01

Advanced environmental barrier coatings are being developed to protect SiC/SiC ceramic matrix composites in harsh combustion environments. The current coating development emphasis has been placed on the significantly improved cyclic durability and combustion environment stability in high-heat-flux and high velocity gas turbine engine environments. Environmental barrier coating systems based on hafnia (HfO2) and ytterbium silicate, HfO2-Si nano-composite bond coat systems have been processed and their stability and thermal conductivity behavior have been evaluated in simulated turbine environments. The incorporation of Silicon Carbide Nanotubes (SiCNT) into high stability (HfO2) and/or HfO2-silicon composite bond coats, along with ZrO2, HfO2 and rare earth silicate composite top coat systems, showed promise as excellent environmental barriers to protect the SiC/SiC ceramic matrix composites.

Fashion design solutions for environmentally conscious consumers

NASA Astrophysics Data System (ADS)

Wagner, M.; Chen, Y.; Curteza, A.; Thomassey, S.; Perwuelz, A.; Zeng, X.

2017-10-01

This paper intends to give an overview of the design solutions in fashion for environmentally conscious consumers, presenting green and ethical practices in contemporary clothing design. The results introduce the concept of slow fashion and discuss available fashion design solutions, giving most prominent examples of sustainable products and brands, these contain one or more design features. By this, the discussion extracts the main contemporary ideas. The presented examples of current offers are all envisioning less impact on the environment and society. Sustainable design solutions use more environmentally friendly materials such as organic cotton, incorporate circular design or design for recycling, e.g., replacing button closures with alternative closing possibilities or leather labels with printed versions, or ensure long product life through durability, among other methods. There are differing designs due to creators’ individuality. This overview can be beneficial for the future development of new solutions for more environmentally friendly fashion.

One-pot polymerization of monolith coated stir bar for high efficient sorptive extraction of perfluoroalkyl acids from environmental water samples followed by high performance liquid chromatography-electrospray tandem mass spectrometry detection.

PubMed

Yao, Xuezi; Zhou, Zhen; He, Man; Chen, Beibei; Liang, Yong; Hu, Bin

2018-06-08

In this work, poly(1-vinylimidazole-ethyleneglycol dimethacrylate) (poly(VI-EDMA)) monolith coated stir bars were synthesized by one-pot polymerization, and they exhibited higher extraction efficiency and faster extraction dynamics for selected PFAAs than commercial ethylene glycol modified silicone (EG-silicone) and polydimethylsiloxane (PDMS) coated stir bars. Taking eleven PFAAs as target analytes, including C4-C12 perfluoroalkyl carboxylates (PFCAs) and C6, C8 perfluoroalkane sulfonates (PFSAs), a method combining monolith-based stir bar sorptive extraction (SBSE) with high performance liquid chromatography (HPLC) - electrospray tandem mass spectrometry (ESI-MS/MS) was proposed for the determination of multiplex PFAAs in environmental water samples. Under the optimized conditions, low limits of detection (0.06-0.40 ng/L) and wide linear range (0.6-400 ng/L) were obtained for target PFAAs with. The developed method was then applied for the analysis of target PFAAs in environmental water samples, and recoveries of 80.1-117% and 80.3-122% were obtained for target PFAAs in spiked Yangtze River and East Lake water samples respectively. Copyright © 2018 Elsevier B.V. All rights reserved.

High-temperature durability considerations for HSCT combustor

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.

1992-01-01

The novel combustor designs for the High Speed Civil Transport will require high temperature materials with long term environmental stability. Higher liner temperatures than in conventional combustors and the need for reduced weight necessitates the use of advanced ceramic matrix composites. The combustor environment is defined at the current state of design, the major degradation routes are discussed for each candidate ceramic material, and where possible, the maximum use temperatures are defined for these candidate ceramics.

Thermal Characterization and Flammability of Structural Epoxy Adhesive and Carbon/Epoxy Composite with Environmental and Chemical Degradation (Postprint)

DTIC Science & Technology

2012-01-01

this study). TGA scans show the thermal degradation of carbon/ epoxy composite by fuel additive at room temperature. Through Microscale Combustion...concerns regarding the durability of structural epoxy adhesive contaminated by hydraulic fluid or fuel additive , under simplified test conditions (no...higher than room tem- perature) or fuel additive (at all temperatures of this study). TGA scans show the thermal degradation of carbon/ epoxy composite

Advanced Lubrication for Energy Efficiency, Durability and Lower Maintenance Costs of Advanced Naval Components and Systems

DTIC Science & Technology

2010-08-20

for transmitting the required power and torque. The proper gear set has also been sized to insure life expectancy of the test rig. The shaft design ...these at minimal cost and great environmental safety. These materials specifically designed on antiwear and extreme pressure chemistries can...nanolubricant additives are designed as surface-stabilized nanomaterials that are dispersed in a hydrocarbon medium for maximum effectiveness. This

Porous graphitic carbon nitride synthesized via direct polymerization of urea for efficient sunlight-driven photocatalytic hydrogen production

NASA Astrophysics Data System (ADS)

Zhang, Yuewei; Liu, Jinghai; Wu, Guan; Chen, Wei

2012-08-01

Energy captured directly from sunlight provides an attractive approach towards fulfilling the need for green energy resources on the terawatt scale with minimal environmental impact. Collecting and storing solar energy into fuel through photocatalyzed water splitting to generate hydrogen in a cost-effective way is desirable. To achieve this goal, low cost and environmentally benign urea was used to synthesize the metal-free photocatalyst graphitic carbon nitride (g-C3N4). A porous structure is achieved via one-step polymerization of the single precursor. The porous structure with increased BET surface area and pore volume shows a much higher hydrogen production rate under simulated sunlight irradiation than thiourea-derived and dicyanamide-derived g-C3N4. The presence of an oxygen atom is presumed to play a key role in adjusting the textural properties. Further improvement of the photocatalytic function can be expected with after-treatment due to its rich chemistry in functionalization.Energy captured directly from sunlight provides an attractive approach towards fulfilling the need for green energy resources on the terawatt scale with minimal environmental impact. Collecting and storing solar energy into fuel through photocatalyzed water splitting to generate hydrogen in a cost-effective way is desirable. To achieve this goal, low cost and environmentally benign urea was used to synthesize the metal-free photocatalyst graphitic carbon nitride (g-C3N4). A porous structure is achieved via one-step polymerization of the single precursor. The porous structure with increased BET surface area and pore volume shows a much higher hydrogen production rate under simulated sunlight irradiation than thiourea-derived and dicyanamide-derived g-C3N4. The presence of an oxygen atom is presumed to play a key role in adjusting the textural properties. Further improvement of the photocatalytic function can be expected with after-treatment due to its rich chemistry in functionalization. Electronic supplementary information (ESI) available: Methods for preparing and characterizing UCN, TCN and DCN samples. Methods for examining the photocatalytic hydrogen production. FTIR, XPS, and digital photos of three products are shown in Fig. S1-6. See DOI: 10.1039/c2nr30948c

31 CFR 240.17 - Powers of attorney.

Code of Federal Regulations, 2010 CFR

2010-07-01

... incompetent. (e) Springing durable special powers of attorney. A springing durable special power of attorney... principal's subsequent incompetence. As with a durable special power of attorney, a springing durable... than those specified in paragraph (b) of this section may be negotiated under a springing durable...

31 CFR 240.17 - Powers of attorney.

Code of Federal Regulations, 2014 CFR

2014-07-01

... incompetent. (e) Springing durable special powers of attorney. A springing durable special power of attorney... principal's subsequent incompetence. As with a durable special power of attorney, a springing durable... than those specified in paragraph (b) of this section may be negotiated under a springing durable...

Self-Propagating Frontal Polymerization in Water at Ambient Pressure

NASA Technical Reports Server (NTRS)

Olten, Nesrin; Kraigsley, Alison; Ronney, Paul D.

2003-01-01

Advances in polymer chemistry have led to the development of monomers and initiation agents that enable propagating free-radical polymerization fronts to exist. These fronts are driven by the exothermicity of the polymerization reaction and the transport of heat from the polymerized product to the reactant monomer/solvent/initiator solution. The thermal energy transported to the reactant solution causes the initiator to decompose, yielding free radicals, which start the free radical polymerization process as discussed in recent reviews. The use of polymerization processes based on propagating fronts has numerous applications. Perhaps the most important of these is that it enables rapid curing of polymers without external heating since the polymerization process itself provides the high temperatures necessary to initiate and sustain polymerization. This process also enables more uniform curing of arbitrarily thick samples since it does not rely on heat transfer from an external source, which will necessarily cause the temperature history of the sample to vary with distance from the surface according to a diffusion-like process. Frontal polymerization also enables filling and sealing of structures having cavities of arbitrary shape without having to externally heat the structure. Water at atmospheric pressure is most convenient solvent to employ and the most important for practical applications (because of the cost and environmental issues associated with DMSO and other solvents). Nevertheless, to our knowledge, steady, self-propagating polymerization fronts have not been reported in water at atmospheric pressure. Currently, polymerization fronts require a high boiling point solvent (either water at high pressures or an alternative solvent such as dimethyl sulfoxide (DMSO) (boiling point 189 C at atmospheric pressure.) Early work on frontal polymerization, employed pressures up to 5000 atm in order to avoid boiling of the monomer/solvent/initiator solution. High boiling point solutions are needed because in order to produce a propagating front, a high front temperature is needed to produce sufficiently rapid decomposition of the free radical initiator and subsequent free radical polymerization and heat release at a rate faster than heat losses remove thermal energy from the system. (While the conduction heat loss rate increases linearly with temperature, the free radical initiator decomposition is a high activation energy process whose rate increases much more rapidly than linearly with temperature, thus as the temperature decreases, the ratio of heat loss to heat generation increases, eventually leading to extinction of the front if the temperature is too low.) In order to obtain atmospheric pressure frontal polymerization in water, it is necessary to identify a monomer/initiator combination that is water soluble and will not extinguish even when the peak temperature (T*) is less than 100 C. In this work acrylic acid (AA) was chosen as the monomer because is it one of the most reactive monomers and can polymerize readily at low temperatures even without initiators. Ammonium persulfate (AP) was chosen as the initiator because it decomposes readily at low temperatures, produces relatively few bubbles and is commercially available. The propagation rates and extinction conditions of the fronts are studied for a range of AA and AP concentrations. Small amounts of fumed silica powder (Cab-o-sil, Cabot Corporation) were added to the solutions to inhibit buoyancy induced convection in the solutions; future studies will investigate the effects of buoyant convection within the solutions.

Cellulose Nanomaterials — A Path Towards Commercialization Workshop Report

Treesearch

Fred Hansen; Victoria Brun; Emily Keller; World Nieh; Theodore Wegner; Michael Meador; Lisa Friedersdorf

2014-01-01

Cellulose nanomaterials are primarily isolated from trees and other organisms; are naturally occurring polymeric materials that have demonstrated great promise for commercial applications across an array of industrial sectors; are renewable and environmentally sustainable; and have the potential to be produced in large volumes (i.e., millions of tons per year). The...

Microwave-assisted synthesis of sucrose polyurethanes and their semi-interpenetrating polymer networks with polycaprolactane and soybean oil

USDA-ARS?s Scientific Manuscript database

Because of the current interest in sustainability, environmental stewardship, and green chemistry, there has been a lot of interest in using agrobased raw materials for the design of polymeric materials. One of the promising biorenewable materials is sucrose, which is inexpensive and widely availabl...

Green materials prepared by using a green processing method: Plant oil-based polymers prepared in CO2 medium with mild conditions

USDA-ARS?s Scientific Manuscript database

Recent efforts have been focused on the development of environmentally friendly replacements for volatile organic solvents. One promising candidate is supercritical carbon dioxide because of its low toxicity and no solvent residues in the final products. Renewed interest in biodegradable polymeric m...

Thin film polymeric gel electrolytes

DOEpatents

Derzon, D.K.; Arnold, C. Jr.; Delnick, F.M.

1996-12-31

Novel hybrid thin film electrolytes, based on an organonitrile solvent system, which are compositionally stable, environmentally safe, can be produced efficiently in large quantity and which, because of their high conductivities {approx_equal}10{sup {minus}3}{Omega}{sup {minus}1} cm{sup {minus}1} are useful as electrolytes for rechargeable lithium batteries. 1 fig.

75 FR 1773 - Notice of Receipt of a Pesticide Petition Filed for Residues of Polymeric Polyhydroxy Acid in or...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-13

... (NAICS code 111). Animal production (NAICS code 112). Food manufacturing (NAICS code 311). Pesticide manufacturing (NAICS code 32532). This listing is not intended to be exhaustive, but rather provides a guide for... Environmental protection, Agricultural commodities, Feed additives, Food additives, Pesticides and pests...

Adsorption of cesium ion by marine actinobacterium Nocardiopsis sp. 13H and their extracellular polymeric substances (EPS) role in bioremediation.

PubMed

Sivaperumal, Pitchiah; Kamala, Kannan; Rajaram, Rajendran

2018-02-01

This paper evaluates the cesium adsorption of marine actinobacterium Nocardiposis sp. 13H strain isolated from nuclear power plant sites in India. It could remove 88.6 ± 0.72% of Cs + from test solution containing 10 mM CsCl 2 . The biosorption of Cs + with different environmental factors such as pH, temperature, and time interval is also determined. Scanning electron microscopy coupled with energy dispersive spectroscopy (EDS) confirmed the Cs + adsorption by Nocardiopsis sp. 13H. Most of the bound cesium was found to be associated extracellular polymeric substances (EPS) suggesting its interaction with the surface active groups. The main component of the EPS was carbohydrate followed by protein and nucleic acid. Further, Fourier transform infrared (FTIR) spectroscopy suggested the carboxyl, hydroxyl, and amide groups on the strain cell surface were likely to be involved in Cs + adsorption. Results from this study show Nocardiopsis sp. 13H microorganism could be useful in exploring the biosorption of radioisotope pollution and developing efficient and eco-friendly biosorbent for environmental cleanup.

Improvement of mechanical properties of polymeric composites: Experimental methods and new systems

NASA Astrophysics Data System (ADS)

Nguyen, Felix Nhanchau

Filler- (e.g., particulate or fiber) reinforced structural polymers or polymeric composites have changed the way things are made. Today, they are found, for example, in air/ground transportation vehicles, sporting goods, ballistic barrier applications and weapons, electronic packaging, musical instruments, fashion items, and more. As the demand increases, so does the desire to have not only well balanced mechanical properties, but also light weight and low cost. This leads to a constant search for novel constituents and additives, new fabrication methods and analytical techniques. To achieve new or improved composite materials requires more than the identification of the right reinforcements to be used with the right polymer matrix at the right loading. Also, an optimized adhesion between the two phases and a toughened matrix system are needed. This calls for new methods to predict, modify and assess the level of adhesion, and new developments in matrix tougheners to minimize compromises in other mechanical/thermal properties. Furthermore, structural optimization, associated with fabrication (e.g., avoidance of fiber-fiber touching or particle aggregation), and sometimes special properties, such as electrical conductivity or magnetic susceptibility are necessary. Finally, the composite system's durability, often under hostile conditions, is generally mandatory. The present study researches new predictive and experimental methods for optimizing and characterizing filler-matrix adhesion and develops a new type of epoxy tougheners. Specifically, (1) a simple thermodynamic parameter evaluated by UNIFAC is applied successfully to screen out candidate adhesion promoters, which is necessary for optimization of the physio-chemical interactions between the two phases; (2) an optical-acoustical mechanical test assisted with an acoustic emission technique is developed to de-convolute filler debonding/delamination among many other micro failure events, and (3) novel core (thermoplastic)-shell (dendrimer) nanoparticles are synthesized and incorporated in epoxy to enhance both stiffness and the polymer's fracture toughness or resistance to crack growth. This unique dendrimer has the possibility of acting both as an adhesion promoter and filler spacer, when applied to the filler surface, and as a matrix enhancer, when combined with other materials, with the unique ability to improve mechanical/thermal/electrical properties. These developments should help in the creation of the next generation of polymeric composites.

Advanced Synthesis of Conductive Polyaniline Using Laccase as Biocatalyst.

PubMed

de Salas, Felipe; Pardo, Isabel; Salavagione, Horacio J; Aza, Pablo; Amougi, Eleni; Vind, Jesper; Martínez, Angel T; Camarero, Susana

2016-01-01

Polyaniline is a conductive polymer with distinctive optical and electrical properties. Its enzymatic synthesis is an environmentally friendly alternative to the use of harsh oxidants and extremely acidic conditions. 7D5L, a high-redox potential laccase developed in our lab, is the biocatalyst of choice for the synthesis of green polyaniline (emeraldine salt) due to its superior ability to oxidize aniline and kinetic stability at the required polymerization conditions (pH 3 and presence of anionic surfactants) as compared with other fungal laccases. Doses as low as 7.6 nM of 7D5L catalyze the polymerization of 15 mM aniline (in 24 h, room temperature, 7% yield) in the presence of different anionic surfactants used as doping templates to provide linear and water-soluble polymers. Aniline polymerization was monitored by the increase of the polaron absorption band at 800 nm (typical for emeraldine salt). Best polymerization results were obtained with 5 mM sodium dodecylbenzenesulfonate (SDBS) as template. At fixed conditions (15 mM aniline and 5mM SDBS), polymerization rates obtained with 7D5L were 2.5-fold the rates obtained with commercial Trametes villosa laccase. Moreover, polyaniline yield was notably boosted to 75% by rising 7D5L amount to 0.15 μM, obtaining 1g of green polyaniline in 1L-reaction volume. The green polymer obtained with the selected system (7D5L/SDBS) holds excellent electrochemical and electro-conductive properties displayed in water-dispersible nanofibers, which is advantageous for the nanomaterial to be readily cast into uniform films for different applications.

Advanced Synthesis of Conductive Polyaniline Using Laccase as Biocatalyst

PubMed Central

de Salas, Felipe; Pardo, Isabel; Salavagione, Horacio J.; Aza, Pablo; Amougi, Eleni; Vind, Jesper; Martínez, Angel T.; Camarero, Susana

2016-01-01

Polyaniline is a conductive polymer with distinctive optical and electrical properties. Its enzymatic synthesis is an environmentally friendly alternative to the use of harsh oxidants and extremely acidic conditions. 7D5L, a high-redox potential laccase developed in our lab, is the biocatalyst of choice for the synthesis of green polyaniline (emeraldine salt) due to its superior ability to oxidize aniline and kinetic stability at the required polymerization conditions (pH 3 and presence of anionic surfactants) as compared with other fungal laccases. Doses as low as 7.6 nM of 7D5L catalyze the polymerization of 15 mM aniline (in 24 h, room temperature, 7% yield) in the presence of different anionic surfactants used as doping templates to provide linear and water-soluble polymers. Aniline polymerization was monitored by the increase of the polaron absorption band at 800 nm (typical for emeraldine salt). Best polymerization results were obtained with 5 mM sodium dodecylbenzenesulfonate (SDBS) as template. At fixed conditions (15 mM aniline and 5mM SDBS), polymerization rates obtained with 7D5L were 2.5-fold the rates obtained with commercial Trametes villosa laccase. Moreover, polyaniline yield was notably boosted to 75% by rising 7D5L amount to 0.15 μM, obtaining 1g of green polyaniline in 1L-reaction volume. The green polymer obtained with the selected system (7D5L/SDBS) holds excellent electrochemical and electro-conductive properties displayed in water-dispersible nanofibers, which is advantageous for the nanomaterial to be readily cast into uniform films for different applications. PMID:27741301

Skylab D024 thermal control coatings and polymeric films experiment

NASA Technical Reports Server (NTRS)

Lehn, William L.; Hurley, Charles J.

1992-01-01

The Skylab D024 Thermal Control Coatings and Polymeric Films Experiment was designed to determine the effects of the external Skylab space environment on the performance and properties of a wide variety of selected thermal control coatings and polymeric films. Three duplicate sets of thermal control coatings and polymeric films were exposed to the Skylab space environment for varying periods of time during the mission. The specimens were retrieved by the astronauts during extravehicular activities (EVA) and placed in hermetically sealed return containers, recovered, and returned to the Wright Laboratory/Materials Laboratory/WPAFB, Ohio for analysis and evaluation. Postflight analysis of the three sets of recovered thermal control coatings indicated that measured changes in specimen thermo-optical properties were due to a combination of excessive contamination and solar degradation of the contaminant layer. The degree of degradation experienced over-rode, obscured, and compromised the measurement of the degradation of the substrate coatings themselves. Results of the analysis of the effects of exposure on the polymeric films and the contamination observed are also presented. The D024 results were used in the design of the LDEF M0003-5 Thermal Control Materials Experiment. The results are presented here to call to the attention of the many other LDEF experimenters the wealth of directly related, low earth orbit, space environmental exposure data that is available from the ten or more separate experiments that were conducted during the Skylab mission. Results of these experiments offer data on the results of low altitude space exposure on materials recovered from space with exposure longer than typical STS experiments for comparison with the LDEF results.

Research Advances on Fabricated Shear Wall System

NASA Astrophysics Data System (ADS)

Liu, Xudong; Wang, Donghui; Wang, Sheng; Zhai, Yu

2018-03-01

With the rapid development of the construction industry, building energy consumption has been increasing, has become a problem that can not be ignored. It is imperative to develop energy-saving buildings. A new type of prefabricated shear wall is assembled and partially assembled by prefabricated parts, and some concrete is spliced together. The new structure has good integrity, seismic resistance and excellent energy saving and environmental protection performance. It reduces building energy consumption to a great extent. Therefore, the design method, manufacturing process, site assembly process and key technical problems of the system are discussed. For the construction industry gradually entered the energy conservation, environmental protection, safety and durability of sustainable development laid the foundation.

Thermal and Environmental Barrier Coating Development for Advanced Propulsion Engine Systems

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.; Fox, Dennis S.

2008-01-01

Ceramic thermal and environmental barrier coatings (TEBCs) are used in gas turbine engines to protect engine hot-section components in the harsh combustion environments, and extend component lifetimes. Advanced TEBCs that have significantly lower thermal conductivity, better thermal stability and higher toughness than current coatings will be beneficial for future low emission and high performance propulsion engine systems. In this paper, ceramic coating design and testing considerations will be described for turbine engine high temperature and high-heat-flux applications. Thermal barrier coatings for metallic turbine airfoils and thermal/environmental barrier coatings for SiC/SiC ceramic matrix composite (CMC) components for future supersonic aircraft propulsion engines will be emphasized. Further coating capability and durability improvements for the engine hot-section component applications can be expected by utilizing advanced modeling and design tools.

Direct visualization of hydrogen absorption dynamics in individual palladium nanoparticles

PubMed Central

Narayan, Tarun C.; Hayee, Fariah; Baldi, Andrea; Leen Koh, Ai; Sinclair, Robert; Dionne, Jennifer A.

2017-01-01

Many energy storage materials undergo large volume changes during charging and discharging. The resulting stresses often lead to defect formation in the bulk, but less so in nanosized systems. Here, we capture in real time the mechanism of one such transformation—the hydrogenation of single-crystalline palladium nanocubes from 15 to 80 nm—to better understand the reason for this durability. First, using environmental scanning transmission electron microscopy, we monitor the hydrogen absorption process in real time with 3 nm resolution. Then, using dark-field imaging, we structurally examine the reaction intermediates with 1 nm resolution. The reaction proceeds through nucleation and growth of the new phase in corners of the nanocubes. As the hydrogenated phase propagates across the particles, portions of the lattice misorient by 1.5%, diminishing crystal quality. Once transformed, all the particles explored return to a pristine state. The nanoparticles' ability to remove crystallographic imperfections renders them more durable than their bulk counterparts. PMID:28091597

Direct visualization of hydrogen absorption dynamics in individual palladium nanoparticles

DOE PAGES

Narayan, Tarun C.; Hayee, Fariah; Baldi, Andrea; ...

2017-01-16

Many energy storage materials undergo large volume changes during charging and discharging. The resulting stresses often lead to defect formation in the bulk, but less so in nanosized systems. Here, we capture in real time the mechanism of one such transformation—the hydrogenation of single-crystalline palladium nanocubes from 15 to 80 nm—to better understand the reason for this durability. First, using environmental scanning transmission electron microscopy, we monitor the hydrogen absorption process in real time with 3 nm resolution. Then, using dark-field imaging, we structurally examine the reaction intermediates with 1 nm resolution. The reaction proceeds through nucleation and growth ofmore » the new phase in corners of the nanocubes. As the hydrogenated phase propagates across the particles, portions of the lattice misorient by 1.5%, diminishing crystal quality. Once transformed, all the particles explored return to a pristine state. As a result, the nanoparticles’ ability to remove crystallographic imperfections renders them more durable than their bulk counterparts.« less

Stable platinum nanoclusters on genomic DNA–graphene oxide with a high oxygen reduction reaction activity

PubMed Central

Tiwari, Jitendra N.; Nath, Krishna; Kumar, Susheel; Tiwari, Rajanish N.; Kemp, K. Christian; Le, Nhien H.; Youn, Duck Hyun; Lee, Jae Sung; Kim, Kwang S.

2013-01-01

Nanosize platinum clusters with small diameters of 2–4 nm are known to be excellent catalysts for the oxygen reduction reaction. The inherent catalytic activity of smaller platinum clusters has not yet been reported due to a lack of preparation methods to control their size (<2 nm). Here we report the synthesis of platinum clusters (diameter ≤1.4 nm) deposited on genomic double-stranded DNA–graphene oxide composites, and their high-performance electrocatalysis of the oxygen reduction reaction. The electrochemical behaviour, characterized by oxygen reduction reaction onset potential, half-wave potential, specific activity, mass activity, accelerated durability test (10,000 cycles) and cyclic voltammetry stability (10,000 cycles) is attributed to the strong interaction between the nanosize platinum clusters and the DNA–graphene oxide composite, which induces modulation in the electronic structure of the platinum clusters. Furthermore, we show that the platinum cluster/DNA–graphene oxide composite possesses notable environmental durability and stability, vital for high-performance fuel cells and batteries. PMID:23900456

Paper-polymer composite devices with minimal fluorescence background.

PubMed

Wang, Chang-Ming; Chen, Chong-You; Liao, Wei-Ssu

2017-04-22

Polymer film incorporated paper-based devices show advantages in simplicity and rugged backing. However, their applications are restricted by the high fluorescence background interference of conventional laminating pouches. Herein, we report a straightforward approach for minimal fluorescence background device fabrication, in which filter paper was shaped and laminated in between two biaxially oriented polypropylene (OPP) and polyvinyl butyral (PVB) composite films. This composite film provides mechanical strength for enhanced device durability, protection from environmental contamination, and prevents reagent degradation. This approach was tested by the determination of copper ions with a fluorescent probe, while the detection of glucose was used to illustrate the improved device durability. Our results show that lamination by the polymer composite lengthens device lifetime, while allowing for fluorescence detection methods combination with greatly reduced fluorescent background widely present in commercially available lamination pouches. By the combination of rapid device prototyping with low cost materials, we believe that this composite design would further expand the potential of paper-based devices. Copyright © 2017 Elsevier B.V. All rights reserved.

Solar cell module lamination process

DOEpatents

Carey, Paul G.; Thompson, Jesse B.; Aceves, Randy C.

2002-01-01

A solar cell module lamination process using fluoropolymers to provide protection from adverse environmental conditions and thus enable more extended use of solar cells, particularly in space applications. A laminate of fluoropolymer material provides a hermetically sealed solar cell module structure that is flexible and very durable. The laminate is virtually chemically inert, highly transmissive in the visible spectrum, dimensionally stable at temperatures up to about 200.degree. C. highly abrasion resistant, and exhibits very little ultra-violet degradation.

The Role of Biomass Composition and Steam Treatment on Durability of Pellets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Yong; Chandra, Richard P.; Sokhansanj, Shahab

Steam treatment has been reported to improve the durability of wood pellet likely by changing the physical and chemical structures of wood particles, but published literature is inconclusive about which structure change is the major reason for enhanced durability. Here, in this paper, steam treatment was combined either with alkaline or with SO 2 to study. The solids obtained after steam treatments along with a control sample were dried and each was compacted into pellets. The pellets were then tested for durability. Steam treatment alone dominated improvements in durability. The pellet durability increased with the amount of xylose, but xylosemore » performed better in the pellet from raw poplar than did in the pellet from treated poplar. Water-soluble components contributed a maximum 4% of the durability of poplar pellets. The addition of lignin and sugars to substrates after steam treatment did not improve durability significantly. The surface modification that took place as a result of size reduction during steam treatment was the major reason, contributing about 50% of the durability of the pellet from steam-treated poplar. The acidity of steam treatment slightly affected the relative contributions of these structure changes on the durability. Lastly, the new knowledge helps tailor the chemical and/or mechanical pretreatment involved in pelleting biomass to durable pellets.« less

The Role of Biomass Composition and Steam Treatment on Durability of Pellets

DOE PAGES

Tang, Yong; Chandra, Richard P.; Sokhansanj, Shahab; ...

2018-03-03

Steam treatment has been reported to improve the durability of wood pellet likely by changing the physical and chemical structures of wood particles, but published literature is inconclusive about which structure change is the major reason for enhanced durability. Here, in this paper, steam treatment was combined either with alkaline or with SO 2 to study. The solids obtained after steam treatments along with a control sample were dried and each was compacted into pellets. The pellets were then tested for durability. Steam treatment alone dominated improvements in durability. The pellet durability increased with the amount of xylose, but xylosemore » performed better in the pellet from raw poplar than did in the pellet from treated poplar. Water-soluble components contributed a maximum 4% of the durability of poplar pellets. The addition of lignin and sugars to substrates after steam treatment did not improve durability significantly. The surface modification that took place as a result of size reduction during steam treatment was the major reason, contributing about 50% of the durability of the pellet from steam-treated poplar. The acidity of steam treatment slightly affected the relative contributions of these structure changes on the durability. Lastly, the new knowledge helps tailor the chemical and/or mechanical pretreatment involved in pelleting biomass to durable pellets.« less

New hybrid latexes from a soybean oil-based waterborne polyurethane and acrylics via emulsion polymerization.

PubMed

Lu, Yongshang; Larock, Richard C

2007-10-01

A series of new waterborne polyurethane (PU)/acrylic hybrid latexes have been successfully synthesized by the emulsion polymerization of acrylic monomers (butyl acrylate and methyl methacrylate) in the presence of a soybean oil-based waterborne PU dispersion using potassium persulfate as an initiator. The waterborne PU dispersion has been synthesized by a polyaddition reaction of toluene 2,4-diisocyanate and a soybean oil-based polyol (SOL). The resulting hybrid latexes, containing 15-60 wt % SOL as a renewable resource, are very stable and exhibit uniform particle sizes of 125 +/- 20 nm as determined by transmittance electronic microscopy. The structure, thermal, and mechanical properties of the resulting hybrid latex films have been investigated by Fourier transform infrared spectroscopy, solid state 13C NMR spectroscopy, dynamic mechanical analysis, extraction, and mechanical testing. Grafting copolymerization of the acrylic monomers onto the PU network occurs during the emulsion polymerization, leading to a significant increase in the thermal and mechanical properties of the resulting hybrid latexes. This work provides a new way of utilizing renewable resources to prepare environmentally friendly hybrid latexes with high performance for coating applications.

Recyclable crosslinked polymer networks with full property recovery made via one-step controlled radical polymerization

NASA Astrophysics Data System (ADS)

Jin, Kailong; Li, Lingqiao; Torkelson, John

Rubber tires illustrate well the issues ranging from economic loss to environmental problems and sustainability issues that arise with spent, covalently crosslinked polymers. A nitroxide-mediated polymerization (NMP) strategy has been developed that allows for one-step synthesis of recyclable crosslinked polymers from monomers or polymers that contain carbon-carbon double bonds amenable to radical polymerization. Resulting materials possess dynamic alkoxyamine crosslinks that undergo reversible decrosslinking as a function of temperature. Using polybutadiene as starting material, and styrene, an appropriate nitroxide molecule and bifunctional initiator for initial crosslinking, a model for tire rubber can be produced by reaction at temperatures comparable to those employed in tire molding. Upon cooling, the crosslinks are made permanent due to the extraordinarily strong temperature dependence of the reverisible nitroxide capping and uncapping reaction. Based on thermomechanical property characterization, when the original crosslinked model rubber is chopped into bits and remolded in the melt state, a well-consolidated material is obtained which exhibits full recovery of properties reflecting crosslink density after multiple recycling steps.

Polyurethane/polymeric N-halamine antimicrobial and biofilm controlling semi-interpenetrating polymer network

NASA Astrophysics Data System (ADS)

Xiu, Kemao

Bacterial infection and biofilm formation cause serious medical, industrial, and environmental problems. In biomedical applications, bacterial contamination of medical devices often leads to infectious diseases accompanied with pain, suffer, and even death. Polyurethane (PU) is widely in biomedical applications due to its good mechanical properties and biocompatibility. However, its vulnerability to bacterial biofilm formation seriously limits its wider uses. Prior studies have shown that N-halamines could be incorporated into PU to achieve antimicrobial and biofilm-controlling effects through grafting, blending, and/or coating. To broaden the selection of modification methods in the development antimicrobial PU, this study synthesized polyurethane/polymeric N-halamine semi-interpenetrating polymer networks (semi-IPN). Polymerizable monomeric N-halamines were swollen into PU with initiators and crosslink agents. Post polymerization of the monomers led to the formation of semi-IPN with linear PU and N-halamine polymer networks. The semi-IPNs showed excellent antimicrobial and biofilm controlling ability towards both gram-positive and gram-negative bacteria. The effects of hydrophilicity, surface grafted N-halamine and structural characteristics of N-halamine on the antimicrobial behavior of the resulting semi-IPNs were also investigated.

Ultraviolet Light Surface Treatment as an Environmentally Benign Process for Production, Maintenance and Repair of Military Composite Structures

NASA Astrophysics Data System (ADS)

Drzal, Lawrence T.

2002-02-01

The principal objective of this work is to develop a low-cost, high-speed, environmentally benign, dry surface treatment method for production, and repair of military composite structures using ultraviolet (UV) light in ambient air. The potential advantage of this method is that it would eliminate volatile organic wastes (VOCs), reduce or eliminate the use of solutions and detergents, and provide a robust surface that would enhance or eliminate the use of solutions and detergents, and provide a robust surface that would enhance the wetting and spreading of paints, coatings and adhesives on polymeric and inorganic surfaces treated by this method. A manufacturing base for UV production equipment is in place although not for this application. There is a need for development of an environmentally friendly, cost effective as well as a robust surface treatment method that can clean a surface as well as create a beneficial chemistry for painting and produce optimum adhesive bonding of polymers, polymer composites and metal surfaces. With this in mind, three main technical objectives were sought in the work. The first objective was to determine the usefulness of UV and UV/O(3) to surface treatments to clean and chemically modify the surface of typical PMCs used in DOD systems. The second objective was to determine the effectiveness of this surface preparation for production and/or repair of adhesively bonded, painted and/or coated polymer matrix composite structures. Finally, a determination of the environmental and performance benefits of this method as a new environmentally benign processing method for the production and/or re air of adhesively SERDP, SERDP collection, robust surface, polymeric surface, inorganic surface, volatile organic compounds (VOC) emissions.

The application of A.C. impedance spectroscopy on the durability of hydrated cement paste subjected to various environmental conditions

NASA Astrophysics Data System (ADS)

Perron, Stacey

Harsh Canadian winters cause many problems in reinforced concrete structures due to damaging freezing-thawing cycles which is exacerbated by the heavy use of de-icing salts on roadways. Evaluation of concrete durability with current ASTM methods may give unreliable results and are destructive to the structure. A relatively new and novel approach to evaluating the durability of concrete uses A. C. Impedance Spectroscopy (ACIS). Hydrated cement paste (hcp), mortar, brick and vycor glass were evaluated using ACIS during drying-rewetting and freezing-thawing cycles. Thermal mechanical analysis (TMA), and differential scanning calorimetry (DSC) tests were also conducted and used as references. Results indicate that ACIS can be used to successfully evaluate the pore structure of hcp. The results from the drying-rewetting cycles are consistent with the pore coarsening theory. ACIS revealed pore structure changes consistent with the mechanical strains and pore solution chemistry. Increased pore continuity with each drying-rewetting cycle was indicated by a reduction in sample resistance. Unique tests were conducted on hydrated cement paste, mortar, brick and vycor glass that measured the ACIS and mechanical strains simultaneously while undergoing temperature changes. The temperature was lowered from 5°C to -80°C and then raised to +20°C. The ACIS results indicate that durability of the material can be assessed using the parameters R, material resistance, and phi, indicative of the frequency dispersion angle. The resistance on freezing values correlates with the amount of pore water freezing. The phi values on freezing are representative of the pore size distribution of the test sample. Resistance and phi data from freezing-thawing tests can be analyzed to assess durability of the sample. A material that is durable to freezing-thawing cycles can be described as having a high resistance at room temperature, a low freezing resistance and small changes in phi. Results were consistent among all the materials tested. Freezing-thawing tests were also conducted on specimens resaturated with salt solutions (5%, 10%, 15%). The results of these tests indicated a lower incipient freezing temperature, increase in pore blockage temperatures, and increased mobility of the pore water during freezing (increase in the change to phi). A series of test were conducted to evaluate the electrode polarization effects associated with the permittivity values at low frequencies. Teflon sheets were used to minimize the electrode polarization effects. It is shown that electrode polarization effects dominate over bulk polarization effects. Effects vary with the porosity of the material.

Cumulative effect of transition metals on nitrogen and fluorine co-doped graphite nanofibers: an efficient and highly durable non-precious metal catalyst for the oxygen reduction reaction.

PubMed

Peera, S Gouse; Arunchander, A; Sahu, A K

2016-08-14

Nitrogen and fluorine co-doped graphite nanofibers (N/F-GNF) and their cumulative effect with Fe and Co have been developed as an alternative non-precious metal catalyst for efficient oxygen reduction reaction (ORR) in acidic media. The synergistic effect between the doped hetero atoms and the co-ordinated Fe and Co towards ORR activity and durability of the catalyst is deeply investigated. A high ORR onset potential comparable with commercial Pt/C catalyst is observed with the Fe-Co/NF-GNF catalyst, which indicates that this catalyst is a potential alternative to Pt/C. A fivefold increase in mass activity is achieved by the Fe-Co/NF-GNF catalyst compared to the simple N/F-GNF catalyst, which endorses the significant role of transition metal atoms in enhancing ORR activity. The advanced Fe-Co/NF-GNF catalyst also exhibits complete tolerance to CH3OH and CO. The Fe-Co/NF-GNF catalyst also exhibits excellent durability towards the ORR with only a 10 mV negative shift in its half wave potential after a 10 000 repeated potential cycling test, whereas in the case of a commercial Pt/C catalyst there was an ∼110 mV negative shift under similar environmental conditions. More stringent corrosive test cycles were also performed by maintaining the cell as high as 1.4 V with a later decrease to 0.6 V vs. RHE for 300 cycles, which showed the excellent durability of the Fe-Co/NF-GNF catalyst in comparison with the Pt/C catalyst. XPS analysis of the Fe-Co/NF-GNF catalyst presents the ORR active chemical states of N (pyridinic-N and graphitic-N) and F (semi-ionic-F) and the co-ordinated sites of Fe and Co species with the dopants. The excellent performance and durability of the Fe-Co/NF-GNF catalyst is due to the synergistic effect between the hetero atoms dopants (N and F) and strong co-ordinating bonds of M-N-C, which protect the graphene layers around the metallic species and greatly mitigates the leaching of Co and Fe during the long term cycling test. The high activity and long term durability of the Fe-Co/NF-GNF catalyst make it a promising ORR electrocatalyst for the fuel cell cathode reaction.

Recycling WEEE: Polymer characterization and pyrolysis study for waste of crystalline silicon photovoltaic modules.

PubMed

Dias, Pablo; Javimczik, Selene; Benevit, Mariana; Veit, Hugo

2017-02-01

Photovoltaic (PV) modules contain both valuable and hazardous materials, which makes its recycling meaningful economically and environmentally. In general, the recycling of PV modules starts with the removal of the polymeric ethylene-vinyl acetate (EVA) resin using pyrolysis, which assists in the recovery of materials such as silicon, copper and silver. The pyrolysis implementation, however, needs improvement given its importance. In this study, the polymers in the PV modules were characterized by Fourier transform infrared spectroscopy (FTIR) and the removal of the EVA resin using pyrolysis has been studied and optimized. The results revealed that 30min pyrolysis at 500°C removes >99% of the polymers present in photovoltaic modules. Moreover, the behavior of different particle size milled modules during the pyrolysis process was evaluated. It is shown that polymeric materials tend to remain at a larger particle size and thus, this fraction has the greatest mass loss during pyrolysis. A thermo gravimetric analysis (TGA) performed in all polymeric matter revealed the optimum pyrolysis temperature is around 500°C. Temperatures above 500°C continue to degrade matter, but mass loss rate is 6.25 times smaller. This study demonstrates the use of pyrolysis can remove >99% of the polymeric matter from PV modules, which assists the recycling of this hazardous waste and avoids its disposal. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of alpha-tocopherol addition to polymeric coatings on the UV and heat resistance of a fibrous collagen material--chrome-free leather

USDA-ARS?s Scientific Manuscript database

UV and heat resistance are very important qualities of leather because most leather products are constantly exposed to outdoor environments. In recent years, we have focused on using environmentally friendly antioxidants that will improve the UV and heat resistance of chrome-free leather. Tocopher...

Direct Quantum Mechanical Simulations of Shocked Energetic Materials

DTIC Science & Technology

2008-12-01

dynamics (QMD) simulations of shocked pentaerythritol tetranitrate (PETN), a conventional high explosive , and the polymeric cubic gauche phase of...nitrogen (cg-N), proposed as an environmentally acceptable energetic alternative to conventional explosive formulations. These simulations, made...stored structural potential energy can be liberated quickly enough, it is possible that explosion can occur with energies several orders of magnitude

Method of preparing thin film polymeric gel electrolytes

DOEpatents

Derzon, D.K.; Arnold, C. Jr.

1997-11-25

Novel hybrid thin film electrolyte is described, based on an organonitrile solvent system, which are compositionally stable, environmentally safe, can be produced efficiently in large quantity and which, because of their high conductivities {approx_equal}10{sup {minus}3}{Omega}{sup {minus}1}cm{sup {minus}1} are useful as electrolytes for rechargeable lithium batteries. 1 fig.

Environmental effects on FOD resistance of composite fan blade

NASA Technical Reports Server (NTRS)

Murphy, G. C.; Selemme, C. T.

1981-01-01

The sensitivity of the impact characteristics of typical polymeric composite fan blade materials to potential limiting combinations of moisture, temperature level and temperature transients was established. The following four technical tasks are reported: (1) evaluation and characterization of constituent blade materials; (2) ballistic impact tests; (3) leading edge impact protection systems; and (4) simulated blade spin impact tests.

Interaction between a recombinant prion protein and organo-mineral complexes as evidenced by CPMAS 13C-NMR

NASA Astrophysics Data System (ADS)

Russo, F.; Scotti, R.; Gianfreda, L.; Conte, P.; Rao, M. A.

2009-04-01

Prion proteins (PrP) are the main responsible for Transmissible Spongiform Encephalopathies (TSE). The TSE etiological agent is a misfolded form of the normal cellular prion protein. The amyloidal aggregates accumulated in the brain of infected animals and mainly composed of PrPSc exhibit resistance to protease attack and many conventional inactivating procedures. The prion protein diseases cause an environmental issue because the environment and in particular the soil compartment can be contaminated and then become a potential reservoir and diffuser of TSEs infectivity as a consequence of (i) accidental dispersion from storage plants of meat and bone meal, (ii) incorporation of contaminated material in fertilizers, (iii) possible natural contamination of pasture soils by grazing herds, and (v) burial of carcasses. The environmental problem can be even more relevant because very low amounts of PrPSc are able to propagate the disease. Several studies evidenced that infectious prion protein remains active in soils for years. Contaminated soils result, thus, a possible critical route of TSE transmission in wild animals. Soil can also protect prion protein toward degradation processes due to the presence of humic substances and inorganic components such as clays. Mineral and organic colloids and the more common association between clay minerals and humic substances can contribute to the adsorption/entrapment of molecules and macromolecules. The polymerization of organic monomeric humic precursors occurring in soil in the presence of oxidative enzymes or manganese and iron oxides, is considered one of the most important processes contributing to the formation of humic substances. The process is very fast and produces a population of polymeric products of different molecular structures, sizes, shapes and complexity. Other molecules and possibly biomacromolecules such as proteins may be involved. The aim of the present work was to study by CPMAS 13C-NMR the interactions between a non pathogenic ovine recombinant prion protein and a model soil system represented by a manganese oxide in the form of birnessite (δ-MnO2), coated with a polymerized catechol. To better understand the effect of the polymerization process, PrP was added to the birnessite-cathecol system either before or after the polymerization processes. The NMR spectra of the prion protein interacting directly with birnessite revealed disappearance of the signals due to the paramagnetic nature of manganese oxide or abiotic degradation. Conversely, the signal pattern of the protein re-appeared as it is mixed to the soil-like system either during or after the catechol polymerization process. Results suggested that the possible interactions of the prion protein on soil systems can be mediated by natural organic matter. However, deeper studies on more complex real soil systems are needed to definitely confirm such hypothesis.