Science.gov

Sample records for modified natural rubber

  1. A study of amino acid modifiers in guayule natural rubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber from the Hevea tree is a critical agricultural material vital to United States industry, medicine, and defense, yet the country is dependent on imports to meet domestic needs. Guayule, a desert shrub indigenous to the US, is under development as an alternative source of natural rubber...

  2. Nanocomposites of natural rubber and polyaniline-modified cellulose nanofibrils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cellulose nanofibrils (CNF) were isolated from cotton microfibrils (CM) by acid hydrolysis and coated with polyaniline (PANI) by in situ polymerization of aniline onto CNF in the presence of hydrochloride acid and ammonium peroxydisulfate to produce CNF/PANI. Nanocomposites of natural rubber (NR) re...

  3. Effect of microfluidized and stearic acid modified soy protein in natural rubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microfluidized and stearic acid modified soy protein aggregates were used to reinforced natural rubber. The size of soy protein particles was reduced with a microfluidizing and ball milling process. Filler size reduction with longer ball milling time tends to increase tensile strength of the rubber ...

  4. Effect of processing methods on the mechanical properties of natural rubber filled with stearic acid modified soy protein particles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber was reinforced with stearic acid modified soy protein particles prepared with a microfluidizing and ball milling process. Longer ball milling time tends to increase tensile strength of the rubber composites. Elastic modulus of the composites increased with the increasing filler concen...

  5. Toughness of natural rubber composites reinforced with hydrolyzed and modified wheat gluten aggregates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The toughness of natural rubber can be improved by using fillers for various rubber applications. Dry wheat gluten is a protein from wheat flour and is sufficiently rigid for rubber reinforcement. The wheat gluten was hydrolyzed to reduce its particle size and microfluidized to reduce and homogenize...

  6. Improved dynamic properties of natural rubber filled with irradiation-modified carbon black

    NASA Astrophysics Data System (ADS)

    Wu, Yongpeng; Wen, Shipeng; Shen, Jing; Jiang, Jian; Hu, Shui; Zhang, Liqun; Liu, Li

    2015-06-01

    In this work, carbon black particles (CBs) were modified by high-energy electron beam (EB) irradiation at different doses. The influence of EB irradiation on the surface and particle size of CBs was investigated. Then, the CBs were compounded with natural rubber (NR), and the mechanical properties and dynamic properties of CBs/NR composite were further researched. The results showed that the irradiated CBs had more oxygen-containing groups and smaller particle sizes than original CBs. After irradiation, the content of bound rubber around the irradiated CBs increased, and the mechanical properties of CBs/NR composite were improved. Most importantly, NR filled with irradiated CBs has lower abrasion, higher wet skid resistance, and lower rolling resistance than NR filled with untreated CBs.

  7. Green natural rubber-g-modified starch for controlling urea release.

    PubMed

    Riyajan, Sa-Ad; Sasithornsonti, Yodsathorn; Phinyocheep, Pranee

    2012-06-01

    The hydrophilicity of natural rubber (NR) was improved by grafting with modified cassava starch (ST) (NR-g-ST) by using potassium persulfate (K2S2O8) as a catalyst. The modified ST was added to NR latex in the presence of Terric16A16 as a non-ionic surfactant at 60 °C for 3 h and cast film on a glass plate to obtain NR-g-ST. The chemical structure of NR-g-ST was confirmed by FTIR. The swelling ratio of NR-g-ST was investigated in water and results showed that the swelling ratio of the modified NR decreased as function of ST. In addition, the tensile strength of the modified NR in the presence of modified ST at 50 phr was the highest value. Also, the thermal stability modified NR-g-ST was higher than of NR/ST blend confirmed by TGA. Finally, the NR-g-ST was used a polymer membrane for controlling urea fertilizer and it easily degraded in soil. This product with good controlled-release and water-retention could be especially useful in agricultural and horticultural applications. PMID:24750631

  8. Compatibilizer for crumb rubber modified asphalt

    SciTech Connect

    Labib, M.E.; Memon, G.M.; Chollar, B.H.

    1996-12-31

    The United States of America discards more than 300 million tires each year, and out of that a large fraction of the tires is dumped into stock piles. This large quantity of tires creates an environmental problem. The use of scrap tires is limited. There is a usage potential in such fields as fuel for combustion and Crumb Rubber-Modified Asphalt binder (CRMA). The use of crumb rubber in modifying asphalt is not a new technique; it is been used since early 1960 by pavement engineers. Crumb rubber is a composite of different blends of natural and synthetic rubber (natural rubber, processing oils, polybutadiene, polystyrene butadiene, and filler). Prior research had concluded that the performance of crumb rubber modified asphalt is asphalt dependent. In some cases it improves the Theological properties and in some cases it degrades the properties of modified asphalt.

  9. Vulcanization characteristics and dynamic mechanical behavior of natural rubber reinforced with silane modified silica.

    PubMed

    Chonkaew, Wunpen; Minghvanish, Withawat; Kungliean, Ulchulee; Rochanawipart, Nutthaya; Brostow, Witold

    2011-03-01

    Two silane coupling agents were used for hydrolysis-condensation reaction modification of nanosilica surfaces. The surface characteristics were analyzed using Fourier transform infrared spectroscopy (FTIR). The vulcanization kinetics of natural rubber (NR) + silica composites was studied and compared to behavior of the neat NR using differential scanning calorimetry (DSC) in the dynamic scan mode. Dynamic mechanical analysis (DMA) was performed to evaluate the effects of the surface modification. Activation energy E(a) values for the reaction are obtained. The presence of silica, modified or otherwise, inhibits the vulcanization reaction of NR. The neat silica containing system has the lowest cure rate index and the highest activation energy for the vulcanization reaction. The coupling agent with longer chains causes more swelling and moves the glass transition temperature T(g) downwards. Below the glass transition region, silica causes a lowering of the dynamic storage modulus G', a result of hindering the cure reaction. Above the glass transition, silica-again modified or otherwise-provides the expected reinforcement effect. PMID:21449342

  10. Initiation of rubber biosynthesis: in vitro comparisons of benzophenone-modified diphosphate analogue structure in three natural rubber-producing species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber is synthesized by initiation with one allylic pyrophosphate (APPs) molecule followed by elongation with thousands of isopentenyl pyrophosphate (IPP) molecules by the enzyme rubber transferase (a cis-prenyl transferase). To better understand how rubber transferase initiates and binds A...

  11. Robust and biodegradable polymer of cassava starch and modified natural rubber.

    PubMed

    Riyajan, Sa-Ad

    2015-12-10

    The application of starch based materials for packaging purposes has attracted significant interest because they are both cheap and renewable resources. The study investigated the preparation and properties of a novel biopolymer sheet produced from a blend of maleated epoxidized natural rubber (MENR) and natural rubber-g-cassava starch (NR-g-CSt). The water resistance, toluene resistance and elongation at break of the polymer blend were enhanced after the addition of the MENR compared to pristine NR-g-CSt. The maximum tensile strength and thermal stability of the NR-g-CSt/MENR blend were found in the 100:50 NR-g-CSt:MENR blend. The novel films demonstrated good biodegradability in soil. PMID:26428124

  12. Thermal properties of hydrogenated liquid natural rubber

    NASA Astrophysics Data System (ADS)

    Jamaluddin, Naharullah; Abdullah, Ibrahim; Yusoff, Siti Fairus M.

    2015-09-01

    Natural rubber (NR) was modified to form liquid natural rubber (LNR) via photooxidative degradation. Hydrogenated liquid natural rubber (HLNR) was synthesized by using diimide as source of hydrogen which the diimide is produced by thermolysis of p-toluenesulfonyl hydrazide (TSH). The structure of HLNR was characterized by determining the changes of main peaks in Fourier Transform infrared and nuclear magnetic resonance spectra after hydrogenation. Thermogravimetric analysis showed that the HLNR had higher decomposition temperature compared to LNR and the decomposition temperature is directly proportional to the percentage of conversion.

  13. Thermal properties of hydrogenated liquid natural rubber

    SciTech Connect

    Jamaluddin, Naharullah; Abdullah, Ibrahim; Yusoff, Siti Fairus M.

    2015-09-25

    Natural rubber (NR) was modified to form liquid natural rubber (LNR) via photooxidative degradation. Hydrogenated liquid natural rubber (HLNR) was synthesized by using diimide as source of hydrogen which the diimide is produced by thermolysis of p-toluenesulfonyl hydrazide (TSH). The structure of HLNR was characterized by determining the changes of main peaks in Fourier Transform infrared and nuclear magnetic resonance spectra after hydrogenation. Thermogravimetric analysis showed that the HLNR had higher decomposition temperature compared to LNR and the decomposition temperature is directly proportional to the percentage of conversion.

  14. Natural Rubber from Domestic Crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The United States is wholly dependent upon imports of natural rubber from tropical countries and is the world’s largest consumer of this strategic raw material. Development of domestic rubber crops will create supply security for this strategic raw material, enhance rural development, and create bio...

  15. Natural rubber latex allergy.

    PubMed

    Deval, Ravi; Ramesh, V; Prasad, G B K S; Jain, Arun Kumar

    2008-01-01

    Natural rubber latex (NRL) is a ubiquitous allergen as it is a component of > 40,000 products in everyday life. Latex allergy might be attributed to skin contact or inhalation of latex particles. Latex allergy is an IgE-mediated hypersensitivity to NRL, presenting a wide range of clinical symptoms such as angioedema, swelling, cough, asthma, and anaphylactic reactions. Until 1979, latex allergy appeared only as type IV delayed hypersensitivity; subsequently, the proportion of different allergy types drifted towards type IV contact allergy reactions. Several risk factors for sensitization to NRL are already known and well documented. Some authors have established a positive correlation between a history of multiple surgical interventions, atopy, spina bifida malformation, and latex allergy incidence. We suspect an increase in latex allergy incidence in association with increased atopy and sensitivity to environmental allergens in the industrial population. It is often postulated in literature that the groups of workers at risk for this allergy are essentially workers in the latex industry and healthcare professionals. In this population, direct internal and mucosal contact with NRL medical devices may be the route of sensitization as factors such as the number of procedures and use of NRL materials (catheters and tubes) were associated with increased risk of latex sensitization and allergy. PMID:18797048

  16. Amino acid modifiers in guayule rubber compounds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tire producers are increasingly interested in biobased materials, including rubber but also as compounding chemicals. An alternative natural rubber for tire use is produced by guayule, a woody desert shrub native to North America. Alternative compounding chemicals include naturally-occurring amino a...

  17. Electrospinning of PVC with natural rubber

    NASA Astrophysics Data System (ADS)

    Othman, Muhammad Hariz; Mohamed, Mahathir; Abdullah, Ibrahim

    2013-11-01

    Polyvinyl chloride (PVC) was mixed with natural rubbers which are liquid natural rubber (LNR), liquid epoxidised natural rubber (LENR) and liquid epoxidised natural rubber acrylate (LENRA) for a preparation of a fine non-woven fiber's mat. PVC and each natural rubbers(PVC:LENR, PVC:LNR and PVC:LENRA) were mixed based on ratio of 70:30. Electrospinning method was used to prepare the fiber. The results show that the spinnable concentration of PVC/ natural rubber/THF solution is 16 wt%. The morphology, diameter, structure and degradation temperature of electrospun fibers were investigated by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). SEM photos showed that the morphology and diameter of the fibers were mainly affected by the addition of natural rubber. TGA results suggested that PVC electrospun fiber has higher degradation temperature than those electrospun fibers that contain natural rubber.

  18. Electrospinning of PVC with natural rubber

    SciTech Connect

    Othman, Muhammad Hariz; Abdullah, Ibrahim; Mohamed, Mahathir

    2013-11-27

    Polyvinyl chloride (PVC) was mixed with natural rubbers which are liquid natural rubber (LNR), liquid epoxidised natural rubber (LENR) and liquid epoxidised natural rubber acrylate (LENRA) for a preparation of a fine non-woven fiber’s mat. PVC and each natural rubbers(PVC:LENR, PVC:LNR and PVC:LENRA) were mixed based on ratio of 70:30. Electrospinning method was used to prepare the fiber. The results show that the spinnable concentration of PVC/ natural rubber/THF solution is 16 wt%. The morphology, diameter, structure and degradation temperature of electrospun fibers were investigated by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). SEM photos showed that the morphology and diameter of the fibers were mainly affected by the addition of natural rubber. TGA results suggested that PVC electrospun fiber has higher degradation temperature than those electrospun fibers that contain natural rubber.

  19. Effects of preparation process on performance of rubber modified asphalt

    NASA Astrophysics Data System (ADS)

    Liu, Hanbing; Luo, Guobao; Wang, Xianqiang; Jiao, Yubo

    2015-06-01

    The rational utilization of waste rubber tire is essential for the environmental protection. Utilizing rubber particles to modify asphalt can not only improve asphalt performance, but also help the recycling of waste materials. Considering the effect of different preparation process parameters on the performance of rubber modified asphalt, this paper analyzes the effects of the shear temperature, shear time and shear rate on the performance of rubber modified asphalt, and provided a reference for its preparation.

  20. Unraveling the Mystery of Natural Rubber Biosynthesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber (NR) is primarily obtained from Hevea brasiliensis, commonly known as the Brazilian rubber tree. As this species contains little genetic variation, it is susceptible to pathogen-based eradication. Consequently, it is imperative that a biomimetic pathway for NR production be developed....

  1. Guayule: A Source of Natural Rubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guayule (Parthenium argentatum Gray) is a perennial shrub native to the Chihuahuan Desert. Guayule's use as a natural rubber source dates before 1500 A.D. when Native Americans used its latex to make balls for games. Guayule has been evaluated in the U.S. as a commercial rubber crop during three per...

  2. Guayule: A Source of Natural Rubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guayule (Parthenium argentatum Gray) is a perennial shrub native to the Chihuahuan Desert. Guayule’s use as a natural rubber source dates before 1500 A.D. when Native Americans used its latex to make balls for games. Guayule has been evaluated in the U.S. as a commercial rubber crop during three per...

  3. Interfacial interaction between the epoxidized natural rubber and silica in natural rubber/silica composites

    NASA Astrophysics Data System (ADS)

    Xu, Tiwen; Jia, Zhixin; Luo, Yuanfang; Jia, Demin; Peng, Zheng

    2015-02-01

    The epoxidized natural rubber (ENR) as an interfacial modifier was used to improve the mechanical and dynamical mechanical properties of NR/silica composites. In order to reveal the interaction mechanism between ENR and silica, the ENR/Silica model compound was prepared by using an open mill and the interfacial interaction of ENR with silica was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and stress-strain testing. The results indicated that the ring-opening reaction occurs between the epoxy groups of ENR chains and Si-OH groups on the silica surfaces and the covalent bonds are formed between two phases, which can improve the dispersion of silica in the rubber matrix and enhance the interfacial combination between rubber and silica. The ring-opening reaction occurs not only in vulcanization process but also in mixing process, meanwhile, the latter seems to be more important due to the simultaneous effects of mechanical force and temperature.

  4. New routes to improve toughness of rubber-modified epoxies

    SciTech Connect

    Pearson, R.A.

    1995-12-31

    Significant progress has been made in modeling the toughening mechanisms in rubber-modified epoxies due to the efforts of many researchers. The result of these efforts has led to an increased awareness of the roles of rubber particle bridging, rubber particle cavitation, matrix dilation, and matrix shear banding on the enhancement of fracture toughness. However, there are still many questions regarding rubber-toughening which remain unanswered. This talk will focus on the importance and the roles of the interphase region between the epoxy matrix and the rubber particle and of the overall particle morphology on the toughness enhancement in rubber-modified epoxies. It will be demonstrated that additional toughness enhancement may be achieved by means not included in any of the toughening models proposed to date. Methods to incorporate these effects into existing toughening models will be discussed.

  5. Anomalous crack propagation in reinforced natural rubber

    NASA Astrophysics Data System (ADS)

    Sotta, Paul; Gabrielle, Brice; Long, Didier; Vanel, Loic; Albouy, Pierre-Antoine; Peditto, Francesca

    2009-03-01

    In reinforced natural rubber, crack propagation in mode I exhibits rotation of the tear in a direction perpendicular to the usual one. Our objective is, first, to understand the impact of this phenomenon on fracture toughness of the material, and, secondly, to understand how this phenomenon is related to the specific properties of reinforced natural rubber. To this aim, we combine measurements of ultimate properties, measurements of the number and length of tear rotations as a function of loading velocity and temperature, and investigation of material heterogeneities at sub-micrometric scales, originating both from fillers and strain-induced crystallites (strain-induced crystallinity is measured up to failure by X ray diffraction), in natural rubber samples reinforced by nanometric aggregates. Observations suggest that tear rotation is related both to the mechanical anisotropy induced by strain-induced crystallinity and to the dissipative properties of the material at high strain.

  6. Fatigue properties of rubber modified pavements. Final report

    SciTech Connect

    Raad, L.; Saboundjian, S.; Yuan, X.

    1995-05-01

    This report presents results of a study to determine the fatigue behavior of rubber modified pavements in Alaska in comparison with conventional asphalt concrete pavements. Laboratory studies were conducted on field specimens using the flexural fatigue test in the controlled-displacement mode. Tests were performed at 72 deg F and 40 deg F. Tested materials include (1) conventional HMA with AC 2.5 and AC 5; (2) PlusRide RUMAC with AC 5; (3) asphalt-rubber concrete with AC 2.5 (wet Process); and (4) rubberized asphalt-rubber concrete with AC 2.5 (wet/dry process).

  7. Investigation of natural latex rubber gloves

    SciTech Connect

    Vessel, E.M.

    1993-03-19

    Seventy five percent of natural latex rubber gloves used in laboratories at the Savannah River Site are not reused. A cost analysis performed by the SRS Procurement Department determined that a net savings of $1,092,210 could be achieved annually by recycling latex rubber gloves. The Materials Technology Section, at the request of the Procurement Department, examined some mechanical and chemical properties of latex rubber gloves manufactured by Ansell Edmont, which had been purchased by the site specifications for protective clothing. It also examined mechanical properties of re-cycled gloves purchased by specifications and of {open_quotes}off the shelf{close_quotes} gloves manufactured by North Brothers Company. Finally, water vapor transmission studies, simulating tritium permeation, were performed on gloves from both manufacturers. These studies were performed to determine whether latex rubber gloves can be recycled or whether using only new, unwashed gloves is required in areas where tritium exposure is a possibility. The results of these studies indicate that the acceptable glove characteristics, required in the WSRC Manual 5Q1.11, Protective Clothing Specifications, are not adversely affected after washing and drying the gloves manufactured by Ansell Edmont for seven cycles. Results also indicate that natural latex rubber gloves manufactured by North Brothers comply with most of the acceptable glove characteristics specified in the WSRC Manual 5Q1.11. Statistical analysis of the water vapor permeation data show that there is no correlation between permeation rates and the manufacturer.

  8. FTIR investigation into Degradation of Natural Rubber

    NASA Astrophysics Data System (ADS)

    Rich, Ryan; Waldek Zerda, T.

    2006-10-01

    The aging of tires is of the highest concerns to the automotive industry, due to its implications in fuel economy and automobile safety. Previously, the high absorption rate of carbon black filled polymers has hindered the use of Fourier Transform Infrared Spectroscopy (FTIR) in studying this occurrence. However, recent developments in attenuated total reflection (ATR) techniques have provided a means for spectroscopically monitoring the composition changes induced in rubber blends by heat, exposure to ultra-violet radiation, and mechanical strain. The ATR apparatus, employing a germanium crystal, collected high quality infrared spectra at a reduced penetration depth of less than one micron. This research analyzed natural polymer blends with varied aggregate size and concentration of carbon black. The samples were analyzed as a function of exposure time to 70 C heat and UV radiation, as well elongation by mechanical strain. In these spectra, growth of the 1740cm-1 peak is assigned to increase populations of the C=O band. Carbon black filler rubber is shown to slow the rate of oxidation in pure natural rubber. Crystallization of rubber composites under strain is characterized by changes in the shapes of the CH stretch bands.

  9. Microbial Degradation of Natural Rubber Vulcanizates

    PubMed Central

    Tsuchii, Akio; Suzuki, Tomoo; Takeda, Kiyoshi

    1985-01-01

    An actinomycete, Nocardia sp. strain 835A, grows well on unvulcanized natural rubber and synthetic isoprene rubber, but not on other types of synthetic rubber. Not only unvulcanized but also various kinds of vulcanized natural rubber products were more or less utilized by the organism as the sole source of carbon and energy. The thin film from a latex glove was rapidly degraded, and the weight loss reached 75% after a 2-week cultivation period. Oligomers with molecular weights from 104 to 103 were accumulated during microbial growth on the latex glove. The partially purified oligomers were examined by infrared and 1H nuclear magnetic resonance and 13C nuclear magnetic resonance spectroscopy, and the spectra were those expected of cis-1, 4-polyisoprene with the structure, OHC—CH2—[—CH2—C(—CH3)=CH —CH2—]n—CH2—C(=O)— CH3, with average values of n of about 114 and 19 for the two oligomers. PMID:16346923

  10. Reinforcement of graphene in natural rubber nanocomposite

    NASA Astrophysics Data System (ADS)

    Azira, A. A.; Kamal, M. M.; Rusop, M.

    2016-07-01

    In the present work, we report the use of graphene as multi-functional nanofiller for natural rubber (NR). Dispersion of reduced graphene into natural rubber (NR) was found to enhance the mechanical and electrical properties of NR. Through a facile approach rubber molecules are successfully grafted onto the surface of graphene. Stable graphene suspension with NR afforded a weblike morphology consisting of platelet networks between the rubber particles, while internal mixer processing broke down this structure, yielding a homogeneous and improved dispersion. The resulting graphene can be dispersed in NR via dry mixing. It is found that graphene is prominent in improving the mechanical properties of NR at low filler loading. The percolation point of graphene in the nanocomposites takes place at a content of less than 0.1 wt%. With incorporation of as low as 0.1 wt% of graphene, an increase in the tensile strength and improvement in the tensile modulus achieved. The improvement in the mechanical properties of NR nanocomposites at such low filler loading is attributed to the strong interfacial interaction and the molecular-level dispersion of graphene in the NR matrix. .

  11. Interface interactions of natural rubber and protein/fiber aggregates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mechanical properties of natural rubber are improved with a renewable filler for rubber applications. Aggregates of protein and fiber that constitute soy protein concentrate were shear-reduced and used to enhance the tensile modulus of the natural rubber. The aqueous dispersion of the shear-reduced ...

  12. Development of Crops To Produce Industrially Useful Natural Rubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber, cis-1,4-polyisoprene, is an essential industrial commodity that most developed countries have to import. Hevea brasiliensis, grown in tropical and subtropical areas is the primary source of natural rubber. The goal of our work is to develop rubber-producing crops suitable for culti...

  13. Development of crops to produce industrially useful natural rubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber, cis-1,4-polyisoprene, is an essential industrial commodity that most developed countries have to import. Hevea brasiliensis (Hevea), grown in tropical and subtropical areas is the primary source of natural rubber. The high quality and quantity of the rubber cause us to focus on und...

  14. Bacterial degradation of natural and synthetic rubber.

    PubMed

    Bode, H B; Kerkhoff, K; Jendrossek, D

    2001-01-01

    The degradation of natural rubber (NR), synthetic poly(cis-1,4-isoprene) (SR), and cross-linked NR (latex gloves) by Gram-positive and Gram-negative bacteria was analyzed by weight loss, gel permeation chromatography, and determination of the protein content. Weight losses of 11-18% and an increase in protein up to 850 microg/mL after incubation of Nocardia sp. DSMZ43191, Streptomyces coelicolor, Streptomyces griseus, bacterial isolate 18a, Acinetobacter calcoaceticus, and Xanthomonas sp. with latex gloves as a carbon source indicated degradation of the polymer. An increase of protein up to 1250 microg/mL was obtained upon incubation of the bacteria with SR. No or only little weight losses and no increase in the protein content were found for nondegrading control strains such as Streptomyces lividans and Streptomyces exfoliatus and for mutants of degrading strains of S. coelicolor and S. griseus, which have been identified by their inability to produce clearing zones on opaque latex agar. Measurement of the average molecular weight of synthetic rubber before and after degradation showed a time-dependent shift to lower values for the degrading strains. Diketone derivates of oligo(cis-1,4-isoprene) were identified as metabolites of rubber degradation. An oxidative degradation pathway of poly(cis-1,4-isoprene) to acetyl-coenzymeA and propionyl-coenzymeA by beta-oxidation is suggested for bacterial degradation of isoprene rubber. PMID:11749186

  15. Natural rubber (NR) biosynthesis: perspectives from polymer chemistry

    SciTech Connect

    Barkakaty, Balaka

    2014-01-01

    Natural rubber is an important strategic raw material for manufacturing a wide variety of industrial products. There are at least 2,500 different latex-producing plant species; however, only Hevea brasiliensis (the Brazilian rubber tree) is a commercial source. The chemical structure of natural rubber is cis-1,4-polyisoprene, but the exact structure of the head and end groups remains unknown. Since synthetic cis-1,4-polyisoprenes cannot match the superior properties of natural rubber, understanding the chemistry behind the biosynthetic process is key to finding a possible replacement. T his chapter summarizes our current understandings from the perspective of a polymer scientist by comparing synthetic polyisoprenes to natural rubber. The chapter also highlights biomimetic polymerization, research towards a synthetic match of natural rubber and the role of natural rubber in health care.

  16. Static and fatigue fracture characteristics of rubber modified epoxy adhesives

    SciTech Connect

    Hosaka, Y.; Miyazaki, K.; Fujii, T.; Okubo, H.; Nejigaka, K.; Kurosawa, K.

    1993-12-31

    A conventional epoxy adhesive is modified with Closs-linked NBR-COOH to increase the fracture toughness. This paper presents the static and fatigue fracture characteristics of the rubber modified epoxy adhesives under Mode 1 loading. The fracture toughness under static loading is measured using Double Cantilever Beam (DCB) specimens. The energy release rate is used as a parameter of fracture toughness. Rubber contents are 2.8% and 5.5% in weight. Generally, toughened adhesives show relatively large plastic deformation ahead the crack tip. The crack extension is thought to be influenced by loading condition. Namely, monotonous loading up to the final failure gives the toughness which is different from the toughness obtained under loading-unloading condition. Therefore, two loading conditions are adopted under static loading in order to show the effect of loading history. Under cyclic loading, the fatigue crack velocity is measured with respect to number of loading cycles. The effect of rubber content on the fatigue crack growth is examined. The effect of adhesive thickness on both static and fatigue fracture also is examined. All tests are conducted at the laboratory condition at room temperature. Following conclusions are obtained from this study. The rubber modified adhesives show higher fracture toughness and fatigue resistance than unmodified one. Higher rubber content always show higher fracture toughness. The effect of rubber content on the fracture toughness is influenced by adhesive thickness. The observed fracture toughness increases with an increase of adhesive thickness while no effect of adherend thickness is found at the present condition. The stable crack extension force is higher than that at the crack starting moment. Rubber modification reduces the fatigue crack velocity. The fracture surface topology becomes different according to rubber content.

  17. Natural Rubber Biosynthesis and a Profitable Guayule Crop

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber (cis-1,4-polyisoprene) is a biopolymer apparently synthesized in plants by a membrane-bound rubber transferase protein complex. The kinetic features of rubber transfereases make them a distinct class of cis-prenyl transferases. The structure of the particular allylic pyrophosphate in...

  18. Micromorphological characterization and label-free quantitation of small rubber particle protein in natural rubber latex.

    PubMed

    Wang, Sai; Liu, Jiahui; Wu, Yanxia; You, Yawen; He, Jingyi; Zhang, Jichuan; Zhang, Liqun; Dong, Yiyang

    2016-04-15

    Commercial natural rubber is traditionally supplied by Hevea brasiliensis, but now there is a big energy problem because of the limited resource and increasing demand. Intensive study of key rubber-related substances is urgently needed for further research of in vitro biosynthesis of natural rubber. Natural rubber is biosynthesized on the surface of rubber particles. A membrane protein called small rubber particle protein (SRPP) is a key protein associated closely with rubber biosynthesis; however, SRPP in different plants has been only qualitatively studied, and there are no quantitative reports so far. In this work, H. brasiliensis was chosen as a model plant. The microscopic distribution of SRPP on the rubber particles during the washing process was investigated by transmission electron microscopy-immunogold labeling. A label-free surface plasmon resonance (SPR) immunosensor was developed to quantify SRPP in H. brasiliensis for the first time. The immunosensor was then used to rapidly detect and analyze SRPP in dandelions and prickly lettuce latex samples. The label-free SPR immunosensor can be a desirable tool for rapid quantitation of the membrane protein SRPP, with excellent assay efficiency, high sensitivity, and high specificity. The method lays the foundation for further study of the functional relationship between SRPP and natural rubber content. PMID:26844871

  19. Toughening epoxy resin with poly(methyl methacrylate)-grafted natural rubber

    SciTech Connect

    Rezaifard, A.H.; Hodd, K.A.; Barton, J.M.

    1993-12-31

    A novel rubber, poly(methyl methacrylate)-g-natural rubber (Hevea-plus MG), has been studied as a toughening agent for bisphenol A diglycidyl ether (Shell 828 epoxy resin) cured with piperidine. Effective dispersions of the rubber, in concentrations of 2-10 parts per hundred parts resin, were achieved by adjusting the solubility parameter of the epoxy to approximate that of poly(methyl methacrylate) by adding bisphenol A. The fracture energy of the rubber-modified resin was determined by compact tension tests (in the temperature range -60 to +40{degrees}C) and by Charpy impact tests. The poly(methyl methacrylate)-g-natural rubber was found to be an effective toughening agent for the epoxy resin at both low and high rates of strain. Possible fracture mechanisms are discussed. 22 refs., 16 figs., 5 tabs.

  20. 21 CFR 177.1640 - Polystyrene and rubber-modified polystyrene.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polystyrene and rubber-modified polystyrene. 177... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1640 Polystyrene and rubber-modified polystyrene. Polystyrene and rubber-modified polystyrene identified in...

  1. 21 CFR 177.1640 - Polystyrene and rubber-modified polystyrene.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Polystyrene and rubber-modified polystyrene. 177... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1640 Polystyrene and rubber-modified polystyrene. Polystyrene and rubber-modified polystyrene identified in...

  2. 21 CFR 177.1640 - Polystyrene and rubber-modified polystyrene.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Polystyrene and rubber-modified polystyrene. 177... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1640 Polystyrene and rubber-modified polystyrene. Polystyrene and rubber-modified polystyrene identified in...

  3. 21 CFR 177.1640 - Polystyrene and rubber-modified polystyrene.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Polystyrene and rubber-modified polystyrene. 177... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1640 Polystyrene and rubber-modified polystyrene. Polystyrene and rubber-modified polystyrene identified in...

  4. 21 CFR 177.1640 - Polystyrene and rubber-modified polystyrene.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Polystyrene and rubber-modified polystyrene. 177... Repeated Use Food Contact Surfaces § 177.1640 Polystyrene and rubber-modified polystyrene. Polystyrene and rubber-modified polystyrene identified in this section may be safely used as components of...

  5. Rubber

    NASA Astrophysics Data System (ADS)

    Graves, D. F.

    The word "rubber" immediately brings to mind materials that are highly flexible and will snap back to their original shape after being stretched. In this chapter a variety of materials are discussed that possess this odd characteristics. There will also be a discussion on the mechanism of this "elastic retractive force." Originally, rubber meant the gum collected from a tree growing in Brazil. The term "rubber" was coined for this material by the English chemist Joseph Priestley, who noted that it was effective for removing pencil marks from paper. Today, in addition to Priestley's natural product, many synthetic materials are made that possess these characteristics and many other properties. The common features of these materials are that they are made up of long-chain molecules that are amorphous (not crystalline), and the chains are above their glass transition temperature at room temperature.

  6. Effect of Nanoclay on Natural Rubber Microstructure

    SciTech Connect

    Carretero-Gonzalez,J.; Retsos, H.; Verdejo, R.; Toki, S.; Hsiao, B.; Giannelis, E.; Lopez-Manchado, M.

    2008-01-01

    The inclusion of highly anisotropic clay nanoparticles (nanoclays) in cross-linked natural rubber (NR) provides a more homogeneous distributed network structure and induces an early onset as well as enhancement of crystallization under uniaxial deformation. The molecular structure of the polymer network and its morphological changes during deformation were characterized by using broadband dielectric spectroscopy and in situ synchrotron wide-angle X-ray diffraction, respectively. It was found that the presence of nanoclay introduces a dual crystallization mechanism due to the alignment of nanoparticles during stretching. The improved properties in NR-nanoclay nanocomposites can be attributed to both microstructural and morphological changes induced by nanoclay as well as to the nanoclay mobility in the NR matrix during crystallization. The interplay of these factors during deformation contributes to the formation of a supernetwork structure containing cross-linked chemical chains, nanofiller, and crystallizable networks with similar length scales.

  7. Isolation of Microorganisms Able To Metabolize Purified Natural Rubber

    PubMed Central

    Heisey, R. M.; Papadatos, S.

    1995-01-01

    Bacteria able to grow on purified natural rubber in the absence of other organic carbon sources were isolated from soil. Ten isolates reduced the weight of vulcanized rubber from latex gloves by >10% in 6 weeks. Scanning electron microscopy clearly revealed the ability of the microorganisms to colonize, penetrate, and dramatically alter the physical structure of the rubber. The rubber-metabolizing bacteria were identified on the basis of fatty acid profiles and cell wall characteristics. Seven isolates were strains of Streptomyces, two were strains of Amycolatopsis, and one was a strain of Nocardia. PMID:16535106

  8. Radiation vulcanization of natural rubber latex with polyfunctional monomers

    SciTech Connect

    Makuuchi, K.; Hagiwara, M.

    1984-03-01

    Natural rubber latex was irradiated with ..gamma..-rays from Co-60 in the presence of polyfunctional monomers to accelerate crosslinking of rubber molecules. Hydrophobic monomers were more effective in accelerating the vulcanization than were hydrophilic monomers. This was ascribed to high solubility of hydrophobic monomers in rubber particles. Among the hydrophobic monomers, neopentylglycol dimethacrylate (NPG) exhibited the highest efficiency in accelerating the vulcanization. Advantages of using NPG are high colloidal stability of the irradiated latex and high thermal stability of dried rubber film.

  9. IDENTIFICATION AND COMPARISON OF NATURAL RUBBER FROM TWO LACTUCA SPECIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Renewed interest in the identification of alternative sources of natural rubber to Hevea brasiliensis has focused on the Compositae family. In our search for Compositae models for rubber synthesis, we extracted latex from stems of two lettuce species: Lactuca serriola, prickly lettuce, and Lactuca...

  10. Natural Rubber Quantification in Sunflower Using an Automated Solvent Extractor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaves of sunflower (Helianthus annuus) produce a small amount of low molecular weight natural rubber (NR) and this species has potential as a rubber-producing crop plant. Quantifying NR in plant tissue has traditionally been accomplished using Soxhlet or gravimetric methodologies. Accelerated solve...

  11. Identification and comparison of natural rubber from two lactuca species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Renewed interest in the identification of alternative sources of natural rubber to Hevea brasiliensis has focused on the Compositae family. In our search for Compositae models for rubber synthesis, we extracted latex from stems of two lettuce species: Lactuca serriola, prickly lettuce, and Lactuca s...

  12. Carboxy terminated rubber based on natural rubber grafted with acid anhydrides and its adhesion properties

    NASA Astrophysics Data System (ADS)

    Klinpituksa, P.; Kongkalai, P.; Kaesaman, A.

    2014-08-01

    The chemical modification of natural rubber by grafting of various polar functional molecules is an essential method, improving the versatility of rubber in applications. This research investigated the preparation of natural rubber-graft-citraconic anhydride (NR-g-CCA), natural rubber-graft-itaconic anhydride (NR-g-ICA), and natural rubber-graft-maleic anhydride (NR-g-MA), with the anhydrides grafted to natural rubber in toluene using benzoyl peroxide as an initiator. Variations of monomer content, initiator content, temperature and reaction time of the grafting copolymerization were investigated. The maximum degrees of grafting were 1.06% for NR-g-CCA, 4.66% for NR-g-ICA, and 5.03% for NR-g-MA, reached using 10 phr citraconic anhydride, 10 phr of itaconic anhydride, or 8 phr of maleic anhydride, 3 phr benzoyl peroxide, at 85, 80 and 80°C for 2, 2 and 3 hrs, respectively. Solvent-based wood adhesives were formulated from these copolymers with various contents of wood resin in the range 10-40 phr. The maximal 289 N/in cleavage peel and 245.7 KPa shear strength for NR-g-MA (5.03% grafting) were obtained at 40 phr wood resin.

  13. Preparation, characterization and conductivity studies of chlorinated natural rubber

    NASA Astrophysics Data System (ADS)

    M, Subburaj; Ramesan, M. T.; Pradyumnan, P. P.

    2014-10-01

    Chlorinated natural rubber (CNR) was prepared by alkaline hydrolysis of chloroform using phase transfer catalyst. The chlorination in CNR was monitored by FTIR and UV spectroscopy and these studies indicated the formation of dichloro cyclopropyl ring to the double bond of natural rubber (NR). XRD and SEM analysis revealed the extent of chlorination in natural rubber. Electrical properties such as AC conductivity, dielectric constant and dielectric loss of CNR was higher than that of NR. Conductivity of NR increased with the increase in the concentration of chlorine percentage. LOI values indicated that the chemical modification imparts better flame resistant to NR.

  14. Radiation-induced vulcanisation of natural rubber latex in presence of styrene-butadiene rubber latex

    NASA Astrophysics Data System (ADS)

    Chaudhari, C. V.; Bhardwaj, Y. K.; Patil, N. D.; Dubey, K. A.; Kumar, Virendra; Sabharwal, S.

    2005-04-01

    Radiation vulcanisation of natural rubber latex in presence of styrene butadiene rubber latex (SBRL) has been investigated. The cast films were characterised for their swelling properties, tensile strength and thermal stability as a function of radiation dose as well as SBRL content. The gel content, tensile strength and thermal stability of the copolymer films were found to increase with increasing the SBRL content in the feed solution and radiation dose.

  15. 21 CFR 801.437 - User labeling for devices that contain natural rubber.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... rubber. 801.437 Section 801.437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... User labeling for devices that contain natural rubber. (a) Data in the Medical Device Reporting System..., natural rubber that contacts humans. The term “natural rubber” includes natural rubber latex, dry...

  16. 21 CFR 801.437 - User labeling for devices that contain natural rubber.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... rubber. 801.437 Section 801.437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... User labeling for devices that contain natural rubber. (a) Data in the Medical Device Reporting System..., natural rubber that contacts humans. The term “natural rubber” includes natural rubber latex, dry...

  17. 21 CFR 801.437 - User labeling for devices that contain natural rubber.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... rubber. 801.437 Section 801.437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... User labeling for devices that contain natural rubber. (a) Data in the Medical Device Reporting System..., natural rubber that contacts humans. The term “natural rubber” includes natural rubber latex, dry...

  18. Rheology of crumb-rubber modified asphalt binders and mixes

    NASA Astrophysics Data System (ADS)

    Sheth, Vikas Rameshchandra

    Laboratory test procedures are presented to determine the rheological properties of crumb rubber modified asphalt (CRMA) binders and mixes. These tests provide simple, fast, and cost-effective alternatives to evaluate the performance (rutting and cracking potential) of binders and mixes used for pavement construction. Viscoelastic properties of CRMA binders are measured using dynamic shear analysis. Master curves were generated using the principle of time-temperature superposition to evaluate the effects of aging, rubber concentration, and curing conditions on the rheology of the modified binder. Results indicate that the rheology of CRMA binders can be divided into three regions of viscoelasticity: glassy region at high frequencies, transition/viscoelastic region at intermediate frequencies, and viscous region at low frequencies. Modification of the asphalt by addition of rubber leads to an improvement in both the high and low temperature properties, as reflected by changes in Gsp' and Gsp{''}, which causes the binder to have a greater resistance to specific pavement failure mechanisms. Both transient and dynamic properties of CRMA mixes were measured in the laboratory using the creep and recovery, direct tension, and frequency sweep tests. Rheological properties of the mix generated from the test data were compared to those of the binder to evaluate the effect of aging, rubber concentration, and curing conditions on mix performance. Several rheological parameters have been identified to characterize the rutting and cracking potential of mixes. A power law equation was found to give good correlations between several mix rheological parameters. Analysis of binder and mix failure energies show that work of cohesion of the binder is negligible compared to the failure energies. A unique relationship between Paris law material parameters has been confirmed. It is also shown that mix failure properties bear a one-to-one correlation with binder failure properties. Based

  19. Hardness and compression resistance of natural rubber and synthetic rubber mixtures

    NASA Astrophysics Data System (ADS)

    Arguello, J. M.; Santos, A.

    2016-02-01

    This project aims to mechanically characterize through compression resistance and shore hardness tests, the mixture of hevea brasiliensis natural rubber with butadiene synthetic rubber (BR), styrene-butadiene rubber (SBR) and ethylene-propylene-diene monomer rubber (EPDM). For each of the studied mixtures were performed 10 tests, each of which increased by 10% the content of synthetic rubber in the mixture; each test consisted of carrying out five tests of compression resistance and five tests of shore hardness. The specimens were vulcanized on a temperature of 160°C, during an approximate time of 15 minutes, and the equipment used in the performance of the mechanical tests were a Shimadzu universal machine and a digital durometer. The results show that the A shore hardness increases directly proportional, with a linear trend, with the content of synthetic BR, SBR or EPDM rubber present in the mixture, being the EPDM the most influential. With respect to the compression resistance is observed that the content of BR or SBR increase this property directly proportional through a linear trend; while the EPDM content also increases but with a polynomial trend.

  20. Preparation of sulfonic acid-containing rubbers from natural rubber vulcanizates

    NASA Astrophysics Data System (ADS)

    Poonsawat, Worapong; Poompradub, Sirilux; Ngamcharussrivichai, Chawalit

    2014-06-01

    In this work, a series of sulfonic acid-containing rubbers were prepared by aqueous phase oxidation of natural rubber vulcanizates in the presence of hydrogen peroxide (H2O2) and formic acid (HCOOH). The starting vulcanizates were neatly prepared via an efficient vulcanization (EV) system by varying mass ratio of N-cyclohexyl-2-benzothiazole sulfonamide (CBS), as an accelerator, to sulfur. The oxidation conditions were controlled at the molar ratio of H2O2: HCOOH = 1:1, the concentration of H2O2 = 15 wt.%, the temperature = 50 °C, and the reaction time = 3 h. The rubber materials before and after the oxidation were characterized for their physicochemical properties by using Fourier transform infrared spectroscopy, bomb calorimetry, acid-base titration and swelling measurements. The results indicated the presence of sulfonic acid group in the oxidized rubbers, generated by the oxidative cleaves of sulfide crosslinks in the rubber vulcanizates. The oxidation decreased the sulfur content of the rubber in which the level of sulfur loss was determined by the CBS/sulfur ratio. Moreover, the acidity of the oxidized products was correlated with the amount of sulfur remaining.

  1. Silencing the lettuce homologs of small rubber particle protein does not influence natural rubber biosynthesis in lettuce (Lactuca sativa).

    PubMed

    Chakrabarty, Romit; Qu, Yang; Ro, Dae-Kyun

    2015-05-01

    Natural rubber, cis-1,4-polyisoprene, is an important raw material in chemical industries, but its biosynthetic mechanism remains elusive. Natural rubber is known to be synthesized in rubber particles suspended in laticifer cells in the Brazilian rubber tree (Hevea brasiliensis). In the rubber tree, rubber elongation factor (REF) and its homolog, small rubber particle protein (SRPP), were found to be the most abundant proteins in rubber particles, and they have been implicated in natural rubber biosynthesis. As lettuce (Lactuca sativa) can synthesize natural rubber, we utilized this annual, transformable plant to examine in planta roles of the lettuce REF/SRPP homologs by RNA interference. Among eight lettuce REF/SRPP homologs identified, transcripts of two genes (LsSRPP4 and LsSRPP8) accounted for more than 90% of total transcripts of REF/SRPP homologs in lettuce latex. LsSRPP4 displays a typical primary protein sequence as other REF/SRPP, while LsSRPP8 is twice as long as LsSRPP4. These two major LsSRPP transcripts were individually and simultaneously silenced by RNA interference, and relative abundance, polymer molecular weight, and polydispersity of natural rubber were analyzed from the LsSRPP4- and LsSRPP8-silenced transgenic lettuce. Despite previous data suggesting the implications of REF/SRPP in natural rubber biosynthesis, qualitative and quantitative alterations of natural rubber could not be observed in transgenic lettuce lines. It is concluded that lettuce REF/SRPP homologs are not critically important proteins in natural rubber biosynthesis in lettuce. PMID:25553584

  2. Rubber.

    ERIC Educational Resources Information Center

    Krishen, Anoop

    1989-01-01

    This review covers methods for identification, characterization, and determination of rubber and materials in rubber. Topics include: general information, nuclear magnetic resonance spectroscopy, infrared spectroscopy, thermal methods, gel permeation chromatography, size exclusion chromatography, analysis related to safety and health, and…

  3. Agronomic and Natural Rubber Characteristics of Sunflower as a Rubber-Producing Plant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sunflower (Helianthus annuus L., Asteraceae) is a genus native to North American and is a potential natural rubber (NR) producing crop. The objectives of the study were to: 1) evaluate commercial sunflower cultivars to determine biomass production and how they partition biomass into leaves, stems, ...

  4. Thermal behavior of crumb-rubber modified asphalt concrete mixtures

    NASA Astrophysics Data System (ADS)

    Epps, Amy Louise

    Thermal cracking is one of the primary forms of distress in asphalt concrete pavements, resulting from either a single drop in temperature to an extreme low or from multiple temperature cycles above the fracture temperature of the asphalt-aggregate mixture. The first mode described is low temperature cracking; the second is thermal fatigue. The addition of crumb-rubber, manufactured from scrap tires, to the binder in asphalt concrete pavements has been suggested to minimize both types of thermal cracking. Four experiments were designed and completed to evaluate the thermal behavior of crumb-rubber modified (CRM) asphalt-aggregate mixtures. Modified and unmodified mixture response to thermal stresses was measured in four laboratory tests. The Thermal Stress Restrained Specimen Test (TSRST) and the Indirect Tensile Test (IDT) were used to compare mixture resistance to low temperature cracking. Modified mixtures showed improved performance, and cooling rate did not affect mixture resistance according to the statistical analysis. Therefore results from tests with faster rates can predict performance under slower field rates. In comparison, predicted fracture temperatures and stresses (IDT) were generally higher than measured values (TSRST). In addition, predicted fracture temperatures from binder test results demonstrated that binder testing alone is not sufficient to evaluate CRM mixtures. Thermal fatigue was explored in the third experiment using conventional load-induced fatigue tests with conditions selected to simulate daily temperature fluctuations. Test results indicated that thermal fatigue may contribute to transverse cracking in asphalt pavements. Both unmodified and modified mixtures had a finite capacity to withstand daily temperature fluctuations coupled with cold temperatures. Modified mixtures again exhibited improved performance. The fourth experiment examined fracture properties of modified and unmodified mixtures using a common fracture toughness test

  5. Modified Silicone-Rubber Tooling For Molding Composite Parts

    NASA Technical Reports Server (NTRS)

    Baucom, Robert M.; Snoha, John J.; Weiser, Erik S.

    1995-01-01

    Reduced-thermal-expansion, reduced-bulk-modulus silicone rubber for use in mold tooling made by incorporating silica powder into silicone rubber. Pressure exerted by thermal expansion reduced even further by allowing air bubbles to remain in silicone rubber instead of deaerating it. Bubbles reduce bulk modulus of material.

  6. 21 CFR 177.1635 - Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... polymerization of p-methylstyrene. (2) Rubber-modified poly(p-methylstyrene) (CAS Reg. No. 33520-88-6) polymer... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Poly(p-methylstyrene) and rubber-modified poly(p... Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene). Poly(p-methylstyrene) and...

  7. GREEN COMPOSITES OF NATURAL RUBBER AND DEFATTED SOY FLOUR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Viscoelastic properties of natural rubber (NR) composites reinforced by defatted soy flour (DSF) are investigated. DSF is an abundant renewable commodity and has a lower material cost than carbon black (CB). DSF contains soy protein, soy carbohydrate, and soy whey. Aqueous dispersion of DSF was b...

  8. Crack analysis of unfilled natural rubber using infrared microspectroscopy

    SciTech Connect

    Neumeister, L.A.; Koenig, J.L.

    1996-10-01

    The characterization and analysis of the crack tip region in unfilled natural rubber is crucial in developing a fatigue resistant material. Therefore, the molecular structure and orientation of the material in the crack tip region has been compared to the bulk. Cracks formed by different methods were evaluated using both transmission and reflection techniques of infrared microspectroscopy. The material around the crack tip and edges shows much higher absorbances than the bulk material for stressed rubber. This is due to more material and predominantly, from residual orientation effects. For unstressed material the crack tip region exhibits identical characteristics to the bulk material.

  9. Fabrication of latex rubber reinforced with micellar nanoparticle as an interface modifier

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reinforced latex rubbers were fabricated by incorporating small amount of nanoparticles as interface modifier. The rubbers were fabricated in a compression mold at 130°C. The incorporated nanoparticles were prepared from wheat protein (gliadin) and ethyl cyanoacrylate (ECA). These nanoparticles were...

  10. Crack analysis of unfilled natural rubber using infrared microspectroscopy

    SciTech Connect

    Neumeister, L.A.; Koenig, J.L.

    1996-12-31

    Several spectroscopic methods are available for characterizing the crack tip region of natural rubber on the molecular scale to develop a material with fatigue resistant properties. Attenuated total reflectance or ATR-IR has been used to characterize the structure of many different polymers, including rubbers. Transmission has also been well established as a viable technique for the molecular characterization of transparent materials including thin films of unfilled natural rubber. Unfilled natural rubber was stretched to 629% elongation until cracks in the surface. A cross section of the sample containing a crack was then microtomed at -85{degrees}C into slices approximately 0.5 {mu}m thick. Similarly, samples were cut with a razor and microtomed under the same conditions. The crack tip region was mapped using the IR{mu}s{trademark}/SIRM Molecular Microanalysis System. The map consisted of ten spectra taken in the x and y directions. The same region was analyzed for orientation of molecular structures. Points were selected along the crack tip, crack edges, and the bulk. Dichroic ratios of all prominent peaks were calculated. ATR was used to verify the results of the mapping experiments for both stressed unstressed material.

  11. Modulus enhancement of natural rubber through the dispersion size reduction of protein/fiber aggregates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improved mechanical properties of natural rubber are required for various rubber applications. Aggregates of protein and fiber that constitute soy protein concentrate were shear-reduced and used to enhance the tensile modulus of natural rubber. The aqueous dispersion of the shear-reduced aggregates ...

  12. Modeling mechanical properties of core-shell rubber-modified epoxies

    SciTech Connect

    Wang, X.; Xiao, K.; Ye, L.; Mai, Y.W.; Wang, C.H.; Rose, L.R.F.

    2000-01-24

    Experiments have been carried out to quantify the effects of rubber content and strain rate on the elastic and plastic deformation behavior of core-shell rubber-modified epoxies. Both the Young's modulus and the yield stress were found to be slightly dependent on strain rate, but very sensitive to the volume fraction of rubber particles. Finite element analyses have also been performed to determine the influences of rubber content on the bulk elasticity modulus and the yield stress. By comparing with experimental results, it is found that the Young's modulus of rubber-toughened epoxies can be accurately estimated using the Mori-Tanaka method, provided that the volume fraction of rubber particles is appropriately evaluated. A yield function is provided that the volume fraction of rubber particles is appropriately evaluated. A yield function is proposed to quantify the effects of hydrostatic stress on the plastic yielding behaviors of rubber-modified epoxies. Agreement with experimental results is good. Also, a visco-plastic model is developed to simulate the strain-rate-dependent stress-strain relations.

  13. Extractable proteins from irradiated field natural rubber latex

    NASA Astrophysics Data System (ADS)

    Rogero, Sizue O.; Lugão, Ademar B.; Yoshii, Fumio; Makuuchi, Keizo

    2003-06-01

    In this study field natural rubber latex was irradiated with different doses near a 60Co gamma source to reduce the water-soluble protein content in the final product. The protein content of the films obtained by casting method was extracted with phosphate buffer solution, pH 7 and was measured using Micro BCA Protein Assay kit. Also was measured protein in the serum samples of field NRL. The concentration of extractable proteins increased with increasing radiation dose.

  14. Method for Molding Structural Parts Utilizing Modified Silicone Rubber

    NASA Technical Reports Server (NTRS)

    Weiser, Erik S. (Inventor); Baucom, Robert M. (Inventor); Snoha, John J. (Inventor)

    1998-01-01

    This invention improves upon a method for molding structural parts from preform material. Preform material to be used for the part is provided. A silicone rubber composition containing entrained air voids is prepared. The silicone rubber and preform material assembly is situated within a rigid mold cavity used to shape the preform material to die desired shape. The entire assembly is heated in a standard heating device so that the thermal expansion of the silicone rubber exerts the pressure necessary to force the preform material into contact with the mold container. The introduction of discrete air voids into the silicone rubber allows for accurately controlled pressure application on the preform material at the cure temperature.

  15. Dynamically vulcanized biobased polylactide/natural rubber blend material with continuous cross-linked rubber phase.

    PubMed

    Chen, Yukun; Yuan, Daosheng; Xu, Chuanhui

    2014-03-26

    We prepared a biobased material, dynamically vulcanized polylactide (PLA)/natural rubber (NR) blend in which the cross-linked NR phase owned a continuous network-like dispersion. This finding breaks the traditional concept of a sea-island morphology formed after dynamic vulcanization of the blends. The scan electron microscopy and dissolution/swell experiments provided the direct proof of the continuous cross-linked NR phase. This new biobased PLA/NR blend material with the novel structure is reported for the first time in the field of dynamic vulcanization and shows promise for development for various functional applications. PMID:24621374

  16. [Residual chemicals in natural rubber products for food contact use].

    PubMed

    Kawamura, Y; Nakajima, A; Yamada, T

    2001-06-01

    The residues of additives and other chemicals were investigated by GC/MS in natural rubber products for food contact, which included nipples, packing, gloves and a net for ham. The packings and gloves contained 980-6,570 micrograms/g of vulcanization accelerators, such as zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate (EZ), zinc di-n-buthyldithiocarbamate (BZ) and 2-mercaptobenzothiazole. Some samples contained BHT, Irganox 1076 and Yoshinox 2246R as antioxidants; dibutyl phthalate and di(2-ethylhexyl) phthalate as plasticizers; and palmitic acid, stearic acid, palmitamide, stearamide and hydrocarbons as lubricants. Two unknown peaks were identified as stigmasterol and beta-sitosterol, and others were estimated to be fucosterol, oryzanol and alpha-sitosterol. These sterols are widely distributed in plants, so their origin was presumed to be the rubber plants. The sterols were detected at a level of 340-2,940 micrograms/g in all natural rubber samples. A migration test was carried out for some samples. No chemicals were released into water, 4% acetic acid or 20% ethanol at 60 degrees C for 30 min, though BHT, Yoshinox 2246R, EZ, BZ and sterols were released into n-heptane at 25 degrees C for 60 min. PMID:11577390

  17. Morphology development of rubber-modified epoxy thermosets

    SciTech Connect

    Kwon, O.; Ward, T.C.

    1996-12-31

    Epoxy thermosets have been widely used as high performance adhesives and matrix resins for composites due to their outstanding mechanical and thermal properties, such as high modulus and tensile strength, high glass transition temperature, high thermal stability, and moisture resistance. Incorporation of a secondary rubbery phase into the glassy epoxy matrix can improve impact and fracture toughness of epoxy thermosets without sacrificing the other desirable properties of the neat epoxy thermoset. During the curing process, the initial homogeneous solution of epoxy resin-curing agent-rubber generally forms rubber-rich and epoxy-rich phases by a phase separation process which is arrested by gelation or vitrification. The final morphology developed by the cure depends on relative rates of cure reaction and phase separation. Cure conditions and the initial rubber composition control the morphology of the system and thus control the mechanical properties of the system.

  18. Tear energy and strain-induced crystallization of natural rubber/styrene-butadiene rubber blend

    NASA Astrophysics Data System (ADS)

    Noguchi, F.; Akabori, K.; Yamamoto, Y.; Kawazura, T.; Kawahara, S.

    2009-08-01

    Strain-induced crystallization of natural rubber (NR), dispersed in styrene-butadiene rubber (SBR), was investigated in relation to dimensional feature of a dispersoid and crosslink density of NR by measuring tear energy (G) of crosslinked NR/SBR blends. The crosslinked NR/SBR blends in ratios of 1/9 and 3/7 by weight were prepared by mixing masticated NR and SBR with an internal mixer at a rotor speed of 30 rpm, followed by crosslinking with dicumyl peroxide on a hot press at 444 K for 60 min. The G, measured in wide-ranges of temperature and tear rate, was superposed into a master curve with a Williams-Landel-Ferry shift factor. The G of the NR/SBR(3/7) blend abruptly decreased to a level comparable to that of SBR at about melting temperature of NR crystals formed on straining. The temperature, at which the dramatic decrease in the G occurred, was associated with the dimensional feature of the NR dispersoid and the crosslink density.

  19. About the cure kinetics in natural rubber/styrene Butadiene rubber blends at 433 K

    NASA Astrophysics Data System (ADS)

    Mansilla, M. A.; Marzocca, A. J.

    2012-08-01

    Vulcanized blends of elastomers are employed in several goods mainly to improve physical properties and reduce costs. One of the most used blends of this kind is that composed by natural rubber (NR) and styrene butadiene rubber (SBR). The cure kinetic of these blends depends mainly on the compound formulation and the cure temperature and time. The preparation method of the blends can influence the mechanical properties of the vulcanized compounds. In this work the cure kinetic at 433 K of NR/SBR blends vulcanized with the system sulfur/TBBS (N-t-butyl-2-benzothiazole sulfenamide) is analyzed in samples prepared by mechanical mixing and solution blending. The two methods produce elastomer domains of NR and SBR, which present different microstructure due to the cure level attained during vulcanization. The cure kinetics is studied by means of rheometer tests and the model proposed by Kamal and Sourour. The analysis of the cure rate is presented and is related to the structure obtained during the vulcanization process.

  20. Toughening effect of strain-induced crystallites in natural rubber.

    PubMed

    Zhang, H P; Niemczura, J; Dennis, G; Ravi-Chandar, K; Marder, M

    2009-06-19

    We study fracture propagation in stretched natural rubber sheets. Experimental results in specimens stretched less than 3.8 times show a monotonic increase in the crack speed with stretch and can be explained by a numerical model based on neo-Hookean theory and Kelvin dissipation. In specimens stretched more than 3.8 times, strain-induced crystallites act as reinforcing and toughening fillers and significantly increase fracture resistance, like nanostructures in other polymeric or biological materials. Consequently, as we increase the amount of stretch, fractures travel slower and slower, and eventually halt altogether. PMID:19659026

  1. Toughening Effect of Strain-Induced Crystallites in Natural Rubber

    NASA Astrophysics Data System (ADS)

    Zhang, H. P.; Niemczura, J.; Dennis, G.; Ravi-Chandar, K.; Marder, M.

    2009-06-01

    We study fracture propagation in stretched natural rubber sheets. Experimental results in specimens stretched less than 3.8 times show a monotonic increase in the crack speed with stretch and can be explained by a numerical model based on neo-Hookean theory and Kelvin dissipation. In specimens stretched more than 3.8 times, strain-induced crystallites act as reinforcing and toughening fillers and significantly increase fracture resistance, like nanostructures in other polymeric or biological materials. Consequently, as we increase the amount of stretch, fractures travel slower and slower, and eventually halt altogether.

  2. 21 CFR 801.437 - User labeling for devices that contain natural rubber.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... environment of the user or patient. (c) Devices containing natural rubber shall be labeled as set forth in... 21 Food and Drugs 8 2010-04-01 2010-04-01 false User labeling for devices that contain natural... User labeling for devices that contain natural rubber. (a) Data in the Medical Device Reporting...

  3. Elastocaloric effect dependence on pre-elongation in natural rubber

    NASA Astrophysics Data System (ADS)

    Xie, Zhongjian; Sebald, Gael; Guyomar, Daniel

    2015-08-01

    In the context of solid-state-cooling, the elastocaloric effect offers a very large controlled entropy change based in low-cost polymers, especially natural rubber which is environmentally friendly. However, large elastocaloric activity requires large elongation (>5), which makes this material impractical for cooling systems due to the large change in sample's area. By performing a pre-elongation, area change is limited, and β = - ∂ γ / ∂ λ (where γ is the specific entropy and λ is the elongation) is larger. The highest β value is obtained when pre-elongation is right before (at the "eve") the onset of the strain-induced crystallization, which is also interpreted in the view of molecular conformation. Experimental results obtained on a natural rubber sample showed an adiabatic temperature change of 4.3 °C for pre-elongation of 4 with further elongation of 4 (true strain change of 69%). Furthermore, the entropy exhibits a quasi-linear dependence on elongation, and the β value is found to be 6400 J K-1 m-3.

  4. Temperature dependence on free volume in cured natural rubber and styrene-butadiene rubber blends

    NASA Astrophysics Data System (ADS)

    Salgueiro, W.; Somoza, A.; Silva, L.; Consolati, G.; Quasso, F.; Mansilla, M. A.; Marzocca, A. J.

    2011-05-01

    A systematic study on the evolution of free volume as a function of the temperature in vulcanized at 433 K natural rubber (NR) and styrene butadiene rubber (SBR) in 25-75, 50-50, 75-25 NR-SBR (percent content of pure NR and SBR, respectively) blends was studied by positron annihilation lifetime spectroscopy. All samples were prepared with sulfur and TBBS (n-t-butyl-2-benzothiazole sulfenamide) as accelerator. The glass transition temperatures of the samples studied were determined by differential scanning calorimetry (DSC) and from lifetime data. In general, a sigmoidal-like complex behavior of the long-lived lifetime component, linked to the nanohole free volume, as a function of the temperature was found. For SBR, the slope of the ortho-positronium lifetime against temperature curves could be well-fitted using a linear function. For blends and also for NR, two different linear functions were necessary. This last behavior is explained in terms of the supercooled process involving a reconfiguration of the elastomeric chains. In the case of blends, the state of cure of NR and SBR in each NR-SBR sample was also taken into account in the discussion of the results obtained. Besides, thermal expansion coefficients of the free volumes in the transition and glassy region of all compounds were estimated. The differences observed in the values of this parameter are discussed by taking into account the morphology and formulation of each blend, the crosslink densities, and the role of the interphases formed between both NR and SBR elastomers.

  5. Extraction and characterization of a natural rubber from Euphorbia characias latex.

    PubMed

    Spanò, Delia; Pintus, Francesca; Mascia, Claudia; Scorciapino, Mariano Andrea; Casu, Mariano; Floris, Giovanni; Medda, Rosaria

    2012-08-01

    A natural rubber was identified and characterized for the first time in the latex of the perennial Mediterranean shrub Euphorbia characias. Four different methods, i.e., acetone, acetic acid, trichloroacetic acid, and Triton® X-100, followed by successive treatments with cyclohexane/ethanol, were employed to extract the natural rubber. The rubber content was shown to be 14% (w/v) of the E. characias latex, a low content compared with that of Hevea brasiliensis (30-35%) but a similar content to other rubber producing plants. E. characias rubber showed a molecular weight of 93,000 with a M(w) /M(n) of 2.9. (1) H NMR, (13) C NMR, and FTIR analysis revealed the characteristic of the cis-1,4-polyisoprene typical of natural rubber. These results provided novel insight into latex components and will ultimately benefit the broader understanding of E. characias latex composition. PMID:22605550

  6. Design of Self-Healing Supramolecular Rubbers by Introducing Ionic Cross-Links into Natural Rubber via a Controlled Vulcanization.

    PubMed

    Xu, Chuanhui; Cao, Liming; Lin, Baofeng; Liang, Xingquan; Chen, Yukun

    2016-07-13

    Introducing ionic associations is one of the most effective approaches to realize a self-healing behavior for rubbers. However, most of commercial rubbers are nonpolar rubbers without now available functional groups to be converted into ionic groups. In this paper, our strategy was based on a controlled peroxide-induced vulcanization to generate massive ionic cross-links via polymerization of zinc dimethacrylate (ZDMA) in natural rubber (NR) and exploited it as a potential self-healable material. We controlled vulcanization process to retard the formation of covalent cross-link network, and successfully generated a reversible supramolecular network mainly constructed by ionic cross-links. Without the restriction of covalent cross-linkings, the NR chains in ionic supramolecular network had good flexibility and mobility. The nature that the ionic cross-links was easily reconstructed and rearranged facilitating the self-healing behavior, thereby enabling a fully cut sample to rejoin and retain to its original properties after a suitable self-healing process at ambient temperature. This study thus demonstrates a feasible approach to impart an ionic association induced self-healing function to commercial rubbers without ionic functional groups. PMID:27337545

  7. Flow properties of natural rubber composites filled with defatted soy flour

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The linear and nonlinear viscoelastic properties of natural rubber composites reinforced with defatted soy flour were studied. Defatted soy flour is an abundant, renewable commodity, and its rigid nature makes it suitable as a reinforcement phase in rubber composites. At small strain, the elastic ...

  8. 2013-2014 Production of guayule natural rubber in Arizona, U.S.A.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber is a unique biopolymer whose physical properties cannot be replicated in synthetic alternatives; therefore, it is required for production of tires (passenger, truck, and aircraft) and thousands of consumer and medical products. While demand for natural rubber is expected to increase ...

  9. PARTICLE SIZE INVESTIGATION ON NATURAL RUBBER FROM DIFFERENT CLONES OF BRAZILIAN IAC SERIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hevea brasiliensis species are being investigated in order to increase the production of natural rubber and to develop new clones more appropriate to specific soil and climate. Particle size of natural rubber from Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell. - Arg. coming from new clones from...

  10. Historical and Recent Achievements in the Field of Microbial Degradation of Natural and Synthetic Rubber

    PubMed Central

    Yikmis, Meral

    2012-01-01

    This review intends to provide an overview of historical and recent achievements in studies of microbial degradation of natural and synthetic rubber. The main scientific focus is on the key enzymes latex-clearing protein (Lcp) from the Gram-positive Streptomyces sp. strain K30 and rubber oxygenase A (RoxA) from the Gram-negative Xanthomonas sp. strain 35Y, which has been hitherto the only known rubber-degrading bacterium that does not belong to the actinomycetes. We also emphasize the importance of knowledge of biodegradation in industrial and environmental biotechnology for waste natural rubber disposal. PMID:22504822

  11. Impact properties of rubber-modified epoxy resin-graphite-fiber composites

    NASA Technical Reports Server (NTRS)

    Gilwee, W. J.; Nir, Z.

    1984-01-01

    To improve the impact resistance of graphite-fiber composites, a commercial and an experimental epoxy resin were modified with liquid reactive rubber and a brominated epoxy resin. The commercial epoxy was a tetrafunctional resin, and the experimental epoxy was a trifunctional resin. The reactive rubber was a carboxyl-terminated butadiene-acrylonitrile copolymer. The rubber content was varied from 0 to 25 percent (wt). The brominated epoxy resin was used at Br levels of 4, 19, and 35 percent of the resin. Composites were prepared with woven graphite cloth reinforcement. The composites were evaluated by using flexural strength in the dry state and an elevated temperature after saturation with water. The impact properties were determined by measuring shear strength after falling-ball impact and instrumented impact. The rubber-modified, trifunctional resin exhibited better properties, when tested in hot-wet conditions in a heated oven at 366 K (after boiling the material for 2 h in demineralized water), than the tetrafunctional resin. Improved impact resistance was observed with the addition of the reactive rubber to the epoxy resin. Further improvement was observed with the addition of the brominated epoxy resin.

  12. Toughening mystery of natural rubber deciphered by double network incorporating hierarchical structures

    NASA Astrophysics Data System (ADS)

    Zhou, Weiming; Li, Xiangyang; Lu, Jie; Huang, Ningdong; Chen, Liang; Qi, Zeming; Li, Liangbin; Liang, Haiyi

    2014-12-01

    As an indispensible material for modern society, natural rubber possesses peerless mechanical properties such as strength and toughness over its artificial analogues, which remains a mystery. Intensive experimental and theoretical investigations have revealed the self-enhancement of natural rubber due to strain-induced crystallization. However a rigorous model on the self-enhancement, elucidating natural rubber's extraordinary mechanical properties, is obscured by deficient understanding of the local hierarchical structure under strain. With spatially resolved synchrotron radiation micro-beam scanning X-ray diffraction we discover weak oscillation in distributions of strain-induced crystallinity around crack tip for stretched natural rubber film, demonstrating a soft-hard double network structure. The fracture energy enhancement factor obtained by utilizing the double network model indicates an enhancement of toughness by 3 orders. It's proposed that upon stretching spontaneously developed double network structures integrating hierarchy at multi length-scale in natural rubber play an essential role in its remarkable mechanical performance.

  13. Gentamicin sulfate-loaded porous natural rubber films for wound dressing.

    PubMed

    Phaechamud, Thawatchai; Issarayungyuen, Pongsathorn; Pichayakorn, Wiwat

    2016-04-01

    Antimicrobial wound dressings have been developed for effectiveness of wound therapy. In this study, gentamicin sulfate was loaded into modified porous natural rubber films. The hydrophilic porous structure in natural rubber films was formed when the polar liquid such as glycerin or triethyl citrate and hydrophilic xanthan gum were blended. Film properties including morphology, drug release, water sorption and erosion, mechanical property, adhesive property, surface free energy, water vapor transmission rate, oxygen permeation, and antimicrobial activity were determined. The angiogenesis activity of films was investigated using chick chorio-allantoic membrane assay. For the system containing triethyl citrate, bi-layers comprising of a dense-top layer and a high porous-bottom layer were observed. Xanthan gum enhanced the water sorption capacity and modified to obtain the optimum rate of the drug release from the film. The developed film topography with dense-top layer induced the low adhesive property, water vapor and oxygen permeability whereas demonstrated good antimicrobial activities against Staphylococcus aureus and Pseudomonas aeruginosa with angiogenic activity. Therefore it had the potential use for medicated wound dressing. PMID:26776874

  14. Modified natural neighbor interpolant

    NASA Astrophysics Data System (ADS)

    Traversoni, Leonardo

    1992-11-01

    Based on the idea of Natural Neighbor Interpolant presented by Sibson in 1980, this paper shows how combining it with the concept of Covering Spheres, new and more practical algorithms can be made as well as a more complete theory.

  15. Thermoplastic nanoclay-modified vulcanizates based on polypropylene and nitrile-butadiene rubber

    NASA Astrophysics Data System (ADS)

    Volfson, Svetoslav I.; Okhotina, Natalya A.; Nigmatullina, Alina I.; Panfilova, Olga A.

    2014-05-01

    Thermoplastic vulcanizates based on polypropylene and nitrile-butadiene rubber, containing modified organoclay were developed. It was shown that composites containing 1 to 5 pbw of Cloisite 15A montmorillonite added to rubber show improved physical-mechanical characteristics. Their swelling degree in AI-92 and motor oil was determined. The swelling degree of composites in petrol and motor oil decreases substantially, by 20-63%, due to the introduction of Cloisite 15A montmorillonite. Modification of thermoplastic vulcanizates using layered silicates raised the degradation onset temperature and decreases weight loss upon high temperature heating.

  16. Recycling crumb rubber modified asphalt pavements (revised). Final research report, September 1992-August 1994

    SciTech Connect

    Crockford, W.W.; Makunike, D.; Davison, R.R.; Scullion, T.; Billiter, T.C.

    1995-07-01

    There has been concern that the legislative mandate to use waste rubber in paving applications will result in a severe environmental problem when it becomes necessary to recycle these pavements. If successful recycling is possible, the long term performance of these pavements becomes a concern. The results of this study indicate that it is possible to recycle this material. However, some techniques for conventional asphalt mixture design, material processing, and construction must be modified to ensure this success, and some techniques may not be appropriate when waste rubber is present in the mixture to be recycled. Many of the results presented in this study are based on experiences in Tyler and San Antonio, Texas, where two of the earliest crumb rubber recycling operations in the United States have transpired.

  17. A Study on the Rheological Properties of Recycled Rubber-Modified Asphalt Mixtures

    PubMed Central

    Karacasu, Murat; Er, Arzu

    2015-01-01

    Using waste rubber in asphalt mixes has become a common practice in road construction. This paper presents the results of a study on the rheological characteristics of rubber-modified asphalt (RMA) concrete under static and dynamic loading conditions. A number of static and dynamic creep tests were conducted on RMA mix specimens with different rubber sizes and contents, and a series of resonant column tests were conducted to evaluate the shear modulus and damping values. To simulate the stress-strain response of traffic-induced loading, the measurements were taken for different confining pressures and strain levels. The results of the study indicated that rubber modification increases stiffness and damping ratio, making it a very attractive material for use in road construction. However the grain size of the rubber is very important. Although RMA may cost up to 100% more than regular asphalt, the advantages it brings, such as an increased service life of the road and proper waste utilization contributing to a more sustainable infrastructure, may justify the added cost. PMID:25695096

  18. A study on the rheological properties of recycled rubber-modified asphalt mixtures.

    PubMed

    Karacasu, Murat; Okur, Volkan; Er, Arzu

    2015-01-01

    Using waste rubber in asphalt mixes has become a common practice in road construction. This paper presents the results of a study on the rheological characteristics of rubber-modified asphalt (RMA) concrete under static and dynamic loading conditions. A number of static and dynamic creep tests were conducted on RMA mix specimens with different rubber sizes and contents, and a series of resonant column tests were conducted to evaluate the shear modulus and damping values. To simulate the stress-strain response of traffic-induced loading, the measurements were taken for different confining pressures and strain levels. The results of the study indicated that rubber modification increases stiffness and damping ratio, making it a very attractive material for use in road construction. However the grain size of the rubber is very important. Although RMA may cost up to 100% more than regular asphalt, the advantages it brings, such as an increased service life of the road and proper waste utilization contributing to a more sustainable infrastructure, may justify the added cost. PMID:25695096

  19. White-Light Emission from Silicone Rubber Modified by 193 nm ArF Excimer Laser

    NASA Astrophysics Data System (ADS)

    Okoshi, Masayuki; Sekine, Daisuke; Inoue, Narumi; Yamashita, Tsugito

    2007-04-01

    The photochemical surface modification of silicone ([SiO(CH3)2]n) rubber has been successfully demonstrated using a 193 nm ArF excimer laser, and white light of strong intensity was emitted upon exposure to a 325 nm He-Cd laser. The photoluminescence spectra of the modified silicone showed broad peaks centered at 410, 550, and 750 nm wavelengths. The modified surface was carbon-free silicon oxide, and the chemical composition ratio of O/Si was approximately 2. However, the surface was not silica glass (SiO2), as clarified by IR spectroscopy. Instead, nanometer-size particles of silicon oxide were formed on the surface of the modified silicone rubber.

  20. A study of protein and amino acids in guayule natural rubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber (NR) from Hevea brasiliensis (the Hevea rubber tree) is a critical agricultural material vital to United States industry, medicine, and defense, yet the country is dependent on NR imports to meet domestic needs. Parthenium argentatum (guayule), a woody desert shrub indigenous to the U...

  1. Effect of concentrated epoxidised natural rubber and silica masterbatch for tyre application

    NASA Astrophysics Data System (ADS)

    Azira, A. A.; Verasamy, D.; Kamal, M. M.

    2016-07-01

    The availability of concentrated epoxidised natural rubber (ENR-LC) has provided a better opportunity for using epoxidised natural rubber (ENR) with silica to reinforce natural rubber for tyre application. ENR-LC mixed directly with silica to rubber by high speed stirrer without using any coupling agent. Some rubber compounds were prepared by mixing a large amount of precipitated amorphous white silica with natural rubber. The silica was prepared in aqueous dispersion and the filler was perfectly dispersed in the ENR-LC. The performance of the composites was evaluated in this work for the viability of ENR-LC/Si in tyre compounding. Compounding was carried out on a two roll mill, where the additives and curing agents was later mixed. Characterization of these composites was performed by Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) for dispersion as well as mechanical testing. C-ENR/Si showed efficient as primary reinforcing filler in ENR with regard to modulus and tensile strength, resulting on an increase in the stiffness of the rubbers compared to ENR latex. Overall improvement in the mechanical properties for the ENR-LC over the control crosslinked rubber sample was probably due to synergisms of silica reinforcement and crosslinking of the polymeric matrix phase.

  2. THERMOOXIDATIVE STUDY OF RAW NATURAL RUBBER FROM BRAZILIAN IAC 300 SERIES CLONES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The improvement of rubber tree species is of key importance due to the worldwide market demand of this renewable material essential for several types of industries. The thermal performance of natural rubber produced from new clones of IAC 300 series, and the Malaysian RRIM 600 clone (used as control...

  3. Natural rubber protein as interfacial enhancement for biobased nano-fillers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber was enhanced with soy protein nano-aggregates and carbon black using a hybrid process. The rubber composites reinforced with an optimum amount of soy protein or soy protein/carbon black showed useful tensile properties. The stress-strain behaviors were analyzed with a micro-mechanical...

  4. 21 CFR 177.1635 - Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) (CAS Reg. No. 24936-41-2) polymer produced by the polymerization of p-methylstyrene. (2) Rubber... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Poly(p-methylstyrene) and rubber-modified poly(p... Components of Single and Repeated Use Food Contact Surfaces § 177.1635 Poly(p-methylstyrene) and...

  5. Comprehensive Proteomics Analysis of Laticifer Latex Reveals New Insights into Ethylene Stimulation of Natural Rubber Production.

    PubMed

    Wang, Xuchu; Wang, Dan; Sun, Yong; Yang, Qian; Chang, Lili; Wang, Limin; Meng, Xueru; Huang, Qixing; Jin, Xiang; Tong, Zheng

    2015-01-01

    Ethylene is a stimulant to increase natural rubber latex. After ethylene application, both fresh yield and dry matter of latex are substantially improved. Moreover, we found that ethylene improves the generation of small rubber particles. However, most genes involved in rubber biosynthesis are inhibited by exogenous ethylene. Therefore, we conducted a proteomics analysis of ethylene-stimulated rubber latex, and identified 287 abundant proteins as well as 143 ethylene responsive latex proteins (ERLPs) with mass spectrometry from the 2-DE and DIGE gels, respectively. In addition, more than 1,600 proteins, including 404 ERLPs, were identified by iTRAQ. Functional classification of ERLPs revealed that enzymes involved in post-translational modification, carbohydrate metabolism, hydrolase activity, and kinase activity were overrepresented. Some enzymes for rubber particle aggregation were inhibited to prolong latex flow, and thus finally improved latex production. Phosphoproteomics analysis identified 59 differential phosphoproteins; notably, specific isoforms of rubber elongation factor and small rubber particle protein that were phosphorylated mainly at serine residues. This post-translational modification and isoform-specific phosphorylation might be important for ethylene-stimulated latex production. These results not only deepen our understanding of the rubber latex proteome but also provide new insights into the use of ethylene to stimulate rubber latex production. PMID:26348427

  6. Comprehensive Proteomics Analysis of Laticifer Latex Reveals New Insights into Ethylene Stimulation of Natural Rubber Production

    PubMed Central

    Wang, Xuchu; Wang, Dan; Sun, Yong; Yang, Qian; Chang, Lili; Wang, Limin; Meng, Xueru; Huang, Qixing; Jin, Xiang; Tong, Zheng

    2015-01-01

    Ethylene is a stimulant to increase natural rubber latex. After ethylene application, both fresh yield and dry matter of latex are substantially improved. Moreover, we found that ethylene improves the generation of small rubber particles. However, most genes involved in rubber biosynthesis are inhibited by exogenous ethylene. Therefore, we conducted a proteomics analysis of ethylene-stimulated rubber latex, and identified 287 abundant proteins as well as 143 ethylene responsive latex proteins (ERLPs) with mass spectrometry from the 2-DE and DIGE gels, respectively. In addition, more than 1,600 proteins, including 404 ERLPs, were identified by iTRAQ. Functional classification of ERLPs revealed that enzymes involved in post-translational modification, carbohydrate metabolism, hydrolase activity, and kinase activity were overrepresented. Some enzymes for rubber particle aggregation were inhibited to prolong latex flow, and thus finally improved latex production. Phosphoproteomics analysis identified 59 differential phosphoproteins; notably, specific isoforms of rubber elongation factor and small rubber particle protein that were phosphorylated mainly at serine residues. This post-translational modification and isoform-specific phosphorylation might be important for ethylene-stimulated latex production. These results not only deepen our understanding of the rubber latex proteome but also provide new insights into the use of ethylene to stimulate rubber latex production. PMID:26348427

  7. Influence of protein hydrolysis on the mechanical properties of natural rubber composites reinforced with soy protein particles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For natural rubber applications, the reinforcing fillers are used to improve the mechanical properties of the rubber. Soy protein particles have been shown to reinforce natural rubber. The hydrolysis conditions of soy protein are studied to understand its effect on the particle size and size distrib...

  8. Ciprofloxacin Release Using Natural Rubber Latex Membranes as Carrier

    PubMed Central

    Dias Murbach, Heitor; Azevedo Borges, Felipe; Romeiro Miranda, Matheus Carlos; Lopes, Rute; Roberto de Barros, Natan; Guedes Mazalli, Alexandre Vinicius; Gonçalves da Silva, Rosângela; Ferreira Cinman, José Luiz; de Camargo Drago, Bruno; Donizetti Herculano, Rondinelli

    2014-01-01

    Natural rubber latex (NRL) from Hevea brasiliensis is easily manipulated, low cost, is of can stimulate natural angiogenesis and cellular adhesion, is a biocompatible, material and presents high mechanical resistance. Ciprofloxacin (CIP) is a synthetic antibiotic (fluoroquinolone) used in the treatment of infection at external fixation screws sites and remote infections, and this use is increasingly frequent in medical practice. The aim of this study was to develop a novel sustained delivery system for CIP based on NRL membranes and to study its delivery system behavior. CIP was found to be adsorbed on the NRL membrane, according to results of energy dispersive X-ray spectroscopy. Results show that the membrane can release CIP for up to 59.08% in 312 hours and the mechanism is due to super case II (non-Fickian). The kinetics of the drug release could be fitted with double exponential function X-ray diffraction and Fourier transform infrared (FTIR) spectroscopy shows some interaction by hydrogen bound, which influences its mechanical behavior. PMID:25587278

  9. Rheological properties of styrene-butadiene rubber filled with electron beam modified surface treated dual phase fillers

    NASA Astrophysics Data System (ADS)

    Shanmugharaj, A. M.; Bhowmick, Anil K.

    2004-01-01

    The rheological properties of styrene-butadiene rubber (SBR) loaded with dual phase filler were measured using Monsanto Processability Tester (MPT) at three different temperatures (100°C, 110°C and 130°C) and four different shear rates (61.3, 306.3, 613, and 1004.5 s -1). The effect of electron beam modification of dual phase filler in absence and presence of trimethylol propane triacrylate (TMPTA) or triethoxysilylpropyltetrasulphide (Si-69) on melt flow properties of SBR was also studied. The viscosity of all the systems decreases with shear rate indicating their pseudoplastic or shear thinning nature. The higher shear viscosity for the SBR loaded with the electron beam modified filler is explained in terms of variation in structure of the filler upon electron beam irradiation. Die swell of the modified filler loaded SBR is slightly higher than that of the unmodified filler loaded rubber, which is explained by calculating normal stress difference for the systems. Activation energy of the modified filler loaded SBR systems is also slightly higher than that of the control filler loaded SBR system.

  10. Advances in rubber/halloysite nanotubes nanocomposites.

    PubMed

    Jia, Zhixin; Guo, Baochun; Jia, Demin

    2014-02-01

    The research advances in rubber/halloysite nanotubes (rubber/HNTs) nanocomposites are reviewed. HNTs are environmentally-friendly natural nanomaterials, which could be used to prepare the rubber-based nanocomposites with high performance and low cost. Unmodified HNTs could be adopted to prepare the rubber/HNTs composites with improved mechanical properties, however, the rubber/HNTs nanocomposites with fine morphology and excellent properties were chiefly prepared with various modifiers by in situ mixing method. A series of rubber/HNTs nanocomposites containing several rubbers (SBR, NR, xSBR, NBR, PU) and different modifiers (ENR, RH, Si69, SA, MAA, ILs) have been investigated. The results showed that all the rubber/HNTs nanocomposites achieved strong interfacial interaction via interfacial covalent bonds, hydrogen bonds or multiple interactions, realized significantly improved dispersion of HNTs at nanoscale and exhibited excellent mechanical performances and other properties. PMID:24749454

  11. Micro-organisms in latex and natural rubber coagula of Hevea brasiliensis and their impact on rubber composition, structure and properties.

    PubMed

    Salomez, M; Subileau, M; Intapun, J; Bonfils, F; Sainte-Beuve, J; Vaysse, L; Dubreucq, E

    2014-10-01

    Natural rubber, produced by coagulation of the latex from the tree Hevea brasiliensis, is an important biopolymer used in many applications for its outstanding properties. Besides polyisoprene, latex is rich in many nonisoprene components such as carbohydrates, proteins and lipids and thereby constitutes a favourable medium for the development of micro-organisms. The fresh rubber coagula obtained by latex coagulation are not immediately processed, allowing the development of various microbial communities. The time period between tree tapping and coagula processing is called maturation, during which an evolution of the properties of the corresponding dry natural rubber occurs. This evolution is partly related to the activity of micro-organisms and to the modification of the biochemical composition. This review synthesizes the current knowledge on microbial populations in latex and natural rubber coagula of H. brasiliensis and the changes they induce on the biochemistry and technical properties of natural rubber during maturation. PMID:24891014

  12. Black curves and creep behaviour of crumb rubber modified binders containing warm mix asphalt additives

    NASA Astrophysics Data System (ADS)

    Gallego, Juan; Rodríguez-Alloza, Ana María; Giuliani, Felice

    2016-03-01

    Warm mix asphalt (WMA) is a new research topic in the field of road pavement materials. This technology allows lower energy consumption and greenhouse gas (GHG) emissions by reducing compaction and placement temperatures of the asphalt mixtures. However, this technology is still under study, and the influence of the WMA additives has yet to be investigated thoroughly and clearly identified, especially in the case of crumb rubber modified (CRM) binders.

  13. Black curves and creep behaviour of crumb rubber modified binders containing warm mix asphalt additives

    NASA Astrophysics Data System (ADS)

    Gallego, Juan; Rodríguez-Alloza, Ana María; Giuliani, Felice

    2016-08-01

    Warm mix asphalt (WMA) is a new research topic in the field of road pavement materials. This technology allows lower energy consumption and greenhouse gas (GHG) emissions by reducing compaction and placement temperatures of the asphalt mixtures. However, this technology is still under study, and the influence of the WMA additives has yet to be investigated thoroughly and clearly identified, especially in the case of crumb rubber modified (CRM) binders.

  14. Hydrogenation of liquid natural rubber via diimide reduction in hydrazine hydrate/hydrogen peroxide system

    NASA Astrophysics Data System (ADS)

    Yusof, Muhammad Jefri Mohd; Jamaluddin, Naharullah; Abdullah, Ibrahim; Yusoff, Siti Fairus M.

    2015-09-01

    Liquid natural rubber (LNR) with molecular weight of lower than 105 and shorter polymeric chain than natural rubber was prepared. LNR was then hydrogenated via diimide reduction by oxidation of hydrazine hydrate with hydrogen peroxide. The unsaturated units of the rubber were converted into saturated hydrocarbon to strengthen the backbone of the polymer so it was able to resist thermal degradation. The results indicated that hydrogenation degree of the product (HLNR) could be extended to 91.2% conversion under appropriate conditions. The hydrogenated LNR (HLNR) was characterized using Fourier-Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopy. The physical characteristics of HLNR were analyzed with Termogravimetric Analysis (TGA).

  15. Hydrogenation of liquid natural rubber via diimide reduction in hydrazine hydrate/hydrogen peroxide system

    SciTech Connect

    Yusof, Muhammad Jefri Mohd; Jamaluddin, Naharullah; Abdullah, Ibrahim; Yusoff, Siti Fairus M.

    2015-09-25

    Liquid natural rubber (LNR) with molecular weight of lower than 10{sup 5} and shorter polymeric chain than natural rubber was prepared. LNR was then hydrogenated via diimide reduction by oxidation of hydrazine hydrate with hydrogen peroxide. The unsaturated units of the rubber were converted into saturated hydrocarbon to strengthen the backbone of the polymer so it was able to resist thermal degradation. The results indicated that hydrogenation degree of the product (HLNR) could be extended to 91.2% conversion under appropriate conditions. The hydrogenated LNR (HLNR) was characterized using Fourier-Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopy. The physical characteristics of HLNR were analyzed with Termogravimetric Analysis (TGA)

  16. Glass Transition and Molecular Mobility in Styrene-Butadiene Rubber Modified Asphalt.

    PubMed

    Khabaz, Fardin; Khare, Rajesh

    2015-11-01

    Asphalt, a soft matter consisting of more than a thousand chemical species, is of vital importance for the transportation infrastructure, yet it poses significant challenges for microscopic theory and modeling approaches due to its multicomponent nature. Polymeric additives can potentially enhance the thermo-mechanical properties of asphalt, thus helping reduce the road repair costs; rational design of such systems requires knowledge of the molecular structure and dynamics of these systems. We have used molecular dynamics (MD) simulations to investigate the volumetric, structural, and dynamic properties of the neat asphalt as well as styrene-butadiene rubber (SBR) modified asphalt systems. The volume-temperature behavior of the asphalt systems exhibited a glass transition phenomenon, akin to that observed in experiments. The glass transition temperature, room temperature density, and coefficient of volume thermal expansion of the neat asphalt systems so evaluated were in agreement with experimental data when the effect of the high cooling rate used in simulations was accounted for. While the volumetric properties of SBR modified asphalt were found to be insensitive to the presence of the SBR additive, the addition of SBR led to an increase in the aggregation of asphaltene molecules. Furthermore, addition of SBR caused a reduction in the mobility of the constituent molecules of asphalt, with the reduction being more significant for the larger constituent molecules. Similar to other glass forming liquids, the reciprocal of the diffusion coefficient of the selected molecules was observed to follow the Vogel-Fulcher-Tammann (VFT) behavior as a function of temperature. These results suggest the potential for using polymeric additives for enhancing the dynamic mechanical properties of asphalt without affecting its volumetric properties. PMID:26451630

  17. Dynamic and structural correlations in nanocomposites of silica with modified surface and carboxylated nitrile rubber.

    PubMed

    Sala, Renata L; Oliveira Xavier, Tatielih P; Venâncio, Tiago; Arantes, Tatiane Moraes; Paranhos, Caio M; Camargo, Emerson R

    2016-03-15

    Distinct affinities between the organic and inorganic phases were observed in nanocomposites prepared through a colloidal route with carboxylated nitrile rubber and modified silica nanoparticles, which resulted in variable mechanical properties and improved thermal stability. Nanoparticles with modified surface affected the macromolecular arrangements of the elastomeric matrix, changing the final mechanical behavior of the nanocomposite, which could be predicted by the spin-lattice relaxation time measured by solid-state NMR. It was also possible to identify how each different nanoparticle affected the molecular dynamic of nanocomposite, correlating the dynamic-mechanical analysis with the NMR data of the saturated carbons of the elastomer. PMID:26745740

  18. Complete genome sequence of Streptomyces sp. strain CFMR 7, a natural rubber degrading actinomycete isolated from Penang, Malaysia.

    PubMed

    Nanthini, Jayaram; Chia, Kim-Hou; Thottathil, Gincy P; Taylor, Todd D; Kondo, Shinji; Najimudin, Nazalan; Baybayan, Primo; Singh, Siddharth; Sudesh, Kumar

    2015-11-20

    Streptomyces sp. strain CFMR 7, which naturally degrades rubber, was isolated from a rubber plantation. Whole genome sequencing and assembly resulted in 2 contigs with total genome size of 8.248 Mb. Two latex clearing protein (lcp) genes which are responsible for rubber degrading activities were identified. PMID:26376470

  19. Natural and synthetic rubber coatings for steel: Properties and compositions. (Latest citations from World Surface Coatings abstracts). Published Search

    SciTech Connect

    Not Available

    1994-04-01

    The bibliography contains citations concerning the application of compositions containing natural and synthetic rubbers to steel. Polyurethane elastomers, chlorinated rubber coatings, and rubber containing acrylic adhesives are among the coatings discussed. Studies of the degradation of rubber coatings applied to steel are included. Bonding properties, adhesion strength, weathering, and anticorrosive properties are discussed. Additional information on anticorrosive coatings may be found in other bibliographies. (Contains a minimum of 180 citations and includes a subject term index and title list.)

  20. Natural and synthetic rubber coatings for steel: Properties and compositions. (Latest citations from World Surface Coatings Abstracts). Published Search

    SciTech Connect

    Not Available

    1993-03-01

    The bibliography contains citations concerning the application of compositions containing natural and synthetic rubbers to steel. Polyurethane elastomers, chlorinated rubber coatings, and rubber containing acrylic adhesives are among the coatings discussed. Studies of the degradation of rubber coatings applied to steel are included. Bonding properties, adhesion strength, weathering, and anticorrosive properties are discussed. Additional information on anticorrosive coatings may be found in other bibliographies. (Contains a minimum of 147 citations and includes a subject term index and title list.)

  1. Natural Rubber-Filler Interactions: What Are the Parameters?

    PubMed

    Chan, Alan Jenkin; Steenkeste, Karine; Canette, Alexis; Eloy, Marie; Brosson, Damien; Gaboriaud, Fabien; Fontaine-Aupart, Marie-Pierre

    2015-11-17

    Reinforcement of a polymer matrix through the incorporation of nanoparticles (fillers) is a common industrial practice that greatly enhances the mechanical properties of the composite material. The origin of such mechanical reinforcement has been linked to the interaction between the polymer and filler as well as the homogeneous dispersion of the filler within the polymer matrix. In natural rubber (NR) technology, knowledge of the conditions necessary to achieve more efficient NR-filler interactions is improving continuously. This study explores the important physicochemical parameters required to achieve NR-filler interactions under dilute aqueous conditions by varying both the properties of the filler (size, composition, surface activity, concentration) and the aqueous solution (ionic strength, ion valency). By combining fluorescence and electron microscopy methods, we show that NR and silica interact only in the presence of ions and that heteroaggregation is favored more than homoaggregation of silica-silica or NR-NR. The interaction kinetics increases with the ion valence, whereas the morphology of the heteroaggregates depends on the size of silica and the volume percent ratio (dry silica/dry NR). We observe dendritic structures using silica with a diameter (d) of 100 nm at a ∼20-50 vol % ratio, whereas we obtain raspberry-like structures using silica with d = 30 nm particles. We observe that in liquid the interaction is controlled by the hydrophilic bioshell, in contrast to dried conditions, where hydrophobic polymer dominates the interaction of NR with the fillers. A good correlation between the nanoscopic aggregation behavior and the macroscopic aggregation dynamics of the particles was observed. These results provide insight into improving the reinforcement of a polymer matrix using NR-filler films. PMID:26488560

  2. Fatigue effect of elastocaloric properties in natural rubber.

    PubMed

    Sebald, Gael; Xie, Zhongjian; Guyomar, Daniel

    2016-08-13

    In the framework of elastocaloric (eC) refrigeration, the fatigue effect on the eC effect of natural rubber (NR) is investigated. Repetitive deformation cycles at engineering strain regime from 1 to 6 results in a rapid rupture (approx. 800 cycles). Degradation of properties and fatigue life are then investigated at three different strain regimes with the same strain amplitude: before onset strain of strain-induced crystallization (SIC) (strain regime of 0-3), onset strain of melting (strain regime of 2-5) and high strain of SIC (strain regime of 4-7). Strain of 0-3 leads to a low eC effect and cracking after 2000 cycles. Strain of 2-5 and 4-7 results in an excellent crack growth resistance and much higher eC effect with adiabatic temperature changes of 3.5 K and 4.2 K, respectively, thanks to the effect of SIC. The eC stress coefficient index γ (ratio between eC temperature change and applied stress) for strains of 2-5 and 4-7 are γ2-5=4.4 K MPa(-1) and γ4-7=1.6 K MPa(-1), respectively, demonstrating the advantage of the strain regime 2-5. Finally, a high-cycle test up to 1.7×10(5) cycles is successfully applied to the NR sample with very little degradation of eC properties, constituting an important step towards cooling applications.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'. PMID:27402933

  3. Surface modification of argon/oxygen plasma treated vulcanized ethylene propylene diene polymethylene surfaces for improved adhesion with natural rubber

    NASA Astrophysics Data System (ADS)

    Basak, Ganesh C.; Bandyopadhyay, Abhijit; Neogi, Sudarsan; Bhowmick, Anil K.

    2011-01-01

    Vulcanized ethylene propylene diene polymethylene (EPDM) rubber surface was treated in a radio frequency capacitatively coupled low pressure argon/oxygen plasma to improve adhesion with compounded natural rubber (NR) during co-vulcanization. The plasma modified surfaces were analyzed by means of contact angle measurement, surface energy, attenuated total reflection-infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive X-ray sulfur mapping and atomic force microscopy. Several experimental variables such as plasma power, length of exposure time and composition of the argon-oxygen gas mixture were considered. It was delineated that plasma treatment changed both surface composition and roughness, and consequently increased peel strength. The change in surface composition was mainly ascribed to the formation of C-O and -Cdbnd O functional groups on the vulcanized surfaces. A maximum of 98% improvement in peel strength was observed after plasma treatment.

  4. Polyacrylamido-2-methyl-1-propane sulfonic acid-grafted-natural rubber as bio-adsorbent for heavy metal removal from aqueous standard solution and industrial wastewater.

    PubMed

    Phetphaisit, Chor Wayakron; Yuanyang, Siriwan; Chaiyasith, Wipharat Chuachuad

    2016-01-15

    Bio-adsorbent modified natural rubber (modified NR) was prepared, by placing the sulfonic acid functional group on the isoprene chain. This modification was carried out with the aim to prepare material capable to remove heavy metals from aqueous solution. The structures of modified NR materials were characterized by FT-IR and NMR spectroscopies. Thermal gravimetric analysis of modified NR showed that the initial degradation temperature of rubber decreases with increasing amount of polyacrylamido-2-methyl-1-propane sulfonic acid (PAMPS) in the structure. In addition, water uptake of the rubber based materials was studied as a function of time and content of PAMPS. The influence of the amount of PAMPS grafted onto NR, time, pH, concentration of metal ions, temperature, and regeneration were studied in terms of their influence on the adsorption of heavy metals (Pb(2+), Cd(2+) and Cu(2+)). The adsorption isotherms of Pb(2+) and Cd(2+) were fitted to the Freundlich isotherm model, while Cu(2+) was fitted to the Langmuir isotherm. However, the results from these two isotherms resulted in a similar behavior. The adsorption capacity of the modified NR for the various heavy metals was in the following order: Pb(2+)∼Cd(2+)>Cu(2+). The maximum adsorption capacities of Pb(2+), Cd(2+), and Cu(2+) were 272.7, 267.2, and 89.7 mg/g of modified rubber, respectively. Moreover, the modified natural rubber was used for the removal of metal ions in real samples of industrial effluents where the efficiency and regeneration were also investigated. PMID:26348149

  5. Toughening mystery of natural rubber deciphered by double network incorporating hierarchical structures.

    PubMed

    Zhou, Weiming; Li, Xiangyang; Lu, Jie; Huang, Ningdong; Chen, Liang; Qi, Zeming; Li, Liangbin; Liang, Haiyi

    2014-01-01

    As an indispensible material for modern society, natural rubber possesses peerless mechanical properties such as strength and toughness over its artificial analogues, which remains a mystery. Intensive experimental and theoretical investigations have revealed the self-enhancement of natural rubber due to strain-induced crystallization. However a rigorous model on the self-enhancement, elucidating natural rubber's extraordinary mechanical properties, is obscured by deficient understanding of the local hierarchical structure under strain. With spatially resolved synchrotron radiation micro-beam scanning X-ray diffraction we discover weak oscillation in distributions of strain-induced crystallinity around crack tip for stretched natural rubber film, demonstrating a soft-hard double network structure. The fracture energy enhancement factor obtained by utilizing the double network model indicates an enhancement of toughness by 3 orders. It's proposed that upon stretching spontaneously developed double network structures integrating hierarchy at multi length-scale in natural rubber play an essential role in its remarkable mechanical performance. PMID:25511479

  6. Toughening mystery of natural rubber deciphered by double network incorporating hierarchical structures

    PubMed Central

    Zhou, Weiming; Li, Xiangyang; Lu, Jie; Huang, Ningdong; Chen, Liang; Qi, Zeming; Li, Liangbin; Liang, Haiyi

    2014-01-01

    As an indispensible material for modern society, natural rubber possesses peerless mechanical properties such as strength and toughness over its artificial analogues, which remains a mystery. Intensive experimental and theoretical investigations have revealed the self-enhancement of natural rubber due to strain-induced crystallization. However a rigorous model on the self-enhancement, elucidating natural rubber's extraordinary mechanical properties, is obscured by deficient understanding of the local hierarchical structure under strain. With spatially resolved synchrotron radiation micro-beam scanning X-ray diffraction we discover weak oscillation in distributions of strain-induced crystallinity around crack tip for stretched natural rubber film, demonstrating a soft-hard double network structure. The fracture energy enhancement factor obtained by utilizing the double network model indicates an enhancement of toughness by 3 orders. It's proposed that upon stretching spontaneously developed double network structures integrating hierarchy at multi length-scale in natural rubber play an essential role in its remarkable mechanical performance. PMID:25511479

  7. Shear Strength of Single Lap Joint Aluminium-Thermoplastic Natural Rubber (Al-TPNR) Laminated Composite

    NASA Astrophysics Data System (ADS)

    Muzakkar, M. Z.; Ahmad, S.; Yarmo, M. A.; Jalar, A.; Bijarimi, M.

    2013-04-01

    In this work, we studied the effect of surface treatment on the aluminium surface and a coupling agent to improve adhesion between aluminium with organic polymer. Thermoplastic natural rubber (TPNR) matrix was prepared by melt blending of natural rubber (NR), liquid natural rubber (LNR) compatibilizer, linear low density polyethylene (LLDPE) and polyethylene grafted maleic anhydride (PE-g-MAH). The PEgMAH concentration used was varied from 0% - 25%. In addition, the aluminium surface was pre-treated with 3-glycidoxy propyl trimethoxy silane (3-GPS) to enhance the mechanical properties of laminated composite. It was found that the shear strength of single lap joint Al-TPNR laminated composite showing an increasing trend as a function of PE-g-MAH contents for the 3-GPS surface treated aluminium. Moreover, the scanning electron microscope (SEM) revealed that the strength improvement was associated with the chemical state of the compound involved.

  8. New Green Polymeric Composites Based on Hemp and Natural Rubber Processed by Electron Beam Irradiation

    PubMed Central

    Stelescu, Maria-Daniela; Craciun, Gabriela; Dumitrascu, Maria

    2014-01-01

    A new polymeric composite based on natural rubber reinforced with hemp has been processed by electron beam irradiation and characterized by several methods. The mechanical characteristics: gel fraction, crosslink density, water uptake, swelling parameters, and FTIR of natural rubber/hemp fiber composites have been investigated as a function of the hemp content and absorbed dose. Physical and mechanical properties present a significant improvement as a result of adding hemp fibres in blends. Our experiments showed that the hemp fibers have a reinforcing effect on natural rubber similar to mineral fillers (chalk, carbon black, silica). The crosslinking rates of samples, measured using the Flory-Rehner equation, increase as a result of the amount of hemp in blends and the electron beam irradiation dose increasing. The swelling parameters of samples significantly depend on the amount of hemp in blends, because the latter have hydrophilic characteristics. PMID:24688419

  9. Structural analysis of sulfur in natural rubber using X-ray absorption near-edge spectroscopy.

    PubMed

    Pattanasiriwisawa, Wanwisa; Siritapetawee, Jaruwan; Patarapaiboolchai, Orasa; Klysubun, Wantana

    2008-09-01

    X-ray absorption near-edge spectroscopy (XANES) has been applied to natural rubber in order to study the local environment of sulfur atoms in sulfur crosslinking structures introduced in the vulcanization process. Different types of chemical accelerators in conventional, semi-efficient and efficient vulcanization systems were investigated. The experimental results show the good sensitivity and reproducibility of XANES to characterize the local geometry and electronic environment of the sulfur K-shell under various conditions of vulcanization and non-vulcanization of natural rubber. Several applications of XANES in this study demonstrate an alternative way of identifying sulfur crosslinks in treated natural rubber based on differences in their spectra and oxidation states. PMID:18728323

  10. Plasma-modified graphene nanoplatelets and multiwalled carbon nanotubes as fillers for advanced rubber composites

    NASA Astrophysics Data System (ADS)

    Sicinski, M.; Gozdek, T.; Bielinski, D. M.; Szymanowski, H.; Kleczewska, J.; Piatkowska, A.

    2015-07-01

    In modern rubber industry, there still is a room for new fillers, which can improve the mechanical properties of the composites, or introduce a new function to the material. Modern fillers like carbon nanotubes or graphene nanoplatelets (GnP), are increasingly applied in advanced polymer composites technology. However, it might be hard to obtain a well dispersed system for such systems. The polymer matrix often exhibits higher surface free energy (SFE) level with the filler, which can cause problems with polymer-filler interphase adhesion. Filler particles are not wet properly by the polymer, and thus are easier to agglomerate. As a consequence, improvement in the mechanical properties is lower than expected. In this work, multi-walled carbon nanotubes (MWCNT) and GnP surface were modified with low-temperature plasma. Attempts were made to graft some functionalizing species on plasma-activated filler surface. The analysis of virgin and modified fillers’ SFE was carried out. MWCNT and GnP rubber composites were produced, and ultimately, their morphology and mechanical properties were studied.

  11. Mechanical and morphological properties of kenaf powder filled natural rubber latex foam

    SciTech Connect

    Karim, Ahmad Fikri Abdul Ariff, Zulkifli Mohamad; Ismail, Hanafi

    2015-07-22

    This research is carried out by incorporate kenaf powder with natural rubber latex (NRL) compound and is foamed to make natural rubber latex foam (NRLF) by using a well known technique called Dunlop method. Different loading of kenaf powder was added to NRL compound and was foamed to make NRLF. The tensile properties, and morphology of kenaf filled NRLF was studied. Increase in kenaf loading reduced the tensile strength and elongation at break and of a compound. Modulus at 100% elongation of the compound increased with increased in filler loading. The morphological and micro structural characterization has been performed by using scanning electron microscopy (SEM)

  12. Securing the future of natural rubber – an American tire and bio-energy platform from guayule

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is a high level of interest in alternative sources of natural rubber for the tire industry due to both the price and supply volatility of Hevea brasiliensis. The guayule plant (Parthenium argentatum) has served as a major source of domestic natural rubber in the early 20th century and is being...

  13. Comparative study on the technological properties of latex and natural rubber from Hancornia speciosa Gomes and Hevea brasiliensis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This work reports a systematic comparative study of the properties of natural lattices and rubbers extracted from Hancornia speciosa Gomes and Hevea brasiliensis [(Willd. ex Adr. de Juss.) Muell.-Arg.] (clone RRIM 600) trees from 11 collections in Brazil throughout 2004. Natural rubber latex particl...

  14. Styrene-butadiene rubber/halloysite nanotubes nanocomposites modified by sorbic acid

    NASA Astrophysics Data System (ADS)

    Guo, Baochun; Chen, Feng; Lei, Yanda; Liu, Xiaoliang; Wan, Jingjing; Jia, Demin

    2009-05-01

    Sorbic acid (SA) was used to improve the performance of styrene-butadiene rubber (SBR)/halloysite nanotubes (HNTs) nanocomposites by direct blending. The detailed mechanisms for the largely improved performance were studied by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), differential scanning calorimetry (DSC), porosity analysis and crosslink density determination. The strong interfacial bonding between HNTs and rubber matrix is resulted through SA intermediated linkages. SA bonds SBR and HNTs through grafting copolymerization/hydrogen bonding mechanism. Significantly improved dispersion of HNTs in virtue of the interactions between HNTs and SA was achieved. Formation of zinc disorbate (ZDS) was revealed during the vulcanization of the composites. However, in the present systems, the contribution of ZDS to the reinforcement was limited. Effects of SA content on the vulcanization behavior, morphology and mechanical properties of the nanocomposites were investigated. Promising mechanical properties of SA modified SBR/HNTs nanocomposites were obtained. The changes in vulcanization behavior, mechanical properties and morphology were correlated with the interactions between HNTs and SA and the largely improved dispersion of HNTs.

  15. Styrene-butadiene rubber/halloysite nanotubes nanocomposites modified by methacrylic acid

    NASA Astrophysics Data System (ADS)

    Guo, Baochun; Lei, Yanda; Chen, Feng; Liu, Xiaoliang; Du, Mingliang; Jia, Demin

    2008-12-01

    Methacrylic acid (MAA) was used to improve the performance of styrene-butadiene rubber (SBR)/halloysite nanotubes (HNTs) nanocomposites by direct blending. The detailed interaction mechanisms of MAA and the in situ formed zinc methacrylate (ZDMA) were revealed by X-ray diffraction (XRD), surface area and porosity analysis, X-ray photoelectron spectroscopy (XPS) together with crosslink density determination. The strong interfacial bonding between HNTs and rubber matrix is resulted through ZDMA and MAA intermediated linkages. ZDMA connects SBR and HNTs via grafting/complexation mechanism. MAA bonds SBR and HNTs through grafting/hydrogen bonding mechanism. Significantly improved dispersion of HNTs in virtue of the interactions between HNTs and MAA or ZDMA was achieved. Effects of MAA content on the vulcanization behavior, morphology and mechanical properties of the nanocomposites were investigated. Promising mechanical properties of MAA modified SBR/HNTs nanocomposites were obtained. The changes in vulcanization behavior, mechanical properties and morphology were correlated with the interactions between HNTs and MAA or ZDMA and the largely improved dispersion of HNTs.

  16. Characterization of asphalt cements modified with crumbed rubber from discarded tires. Final report

    SciTech Connect

    Daly, W.H.; Negulescu, I.I.

    1994-11-01

    The potential legislative requirement for incorporation of scrap rubber into asphalt blends mandated a thorough evaluation of the influence of scrap rubber additives on the physical properties and aging characteristics of rubber/asphalt blends. Blends with up to 20 percent ground vulcanized rubber (both crumb and 200 mesh powder particles) from recycled tires were prepared with asphalt cements of various grades (AC5 - AC30) and evaluated using DMA. Blends produced from powdered rubber particles exhibited Newtonian behavior at high temperatures; similar behavior was not observed with crumb rubber blends. The mechanical properties of asphalt-rubber blends depend upon the concentration of rubber additives, the particle dimensions, and the chemical composition of the asphalt.

  17. Protein influences on guayule and Hevea natural rubber sol and gel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guayule (Parthenium argentatum) is under cultivation in the southwestern United States as an alternative source of natural rubber free from proteins that cause Type I latex allergies. However, since guayule lacks the protein-polymer interactions present in Hevea latex, its physical and chemical prop...

  18. Elemental Analysis and Protein Quantification of Raw Natural Rubber of IAC Series 400 Clones

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protein, nitrogen and sulfur contents were investigated for natural rubber from commercial Hevea, synthetic polyisoprene, and new IAC clones from Mococa city (IAC 405, 406, 410, 413, and 420), Jaú city (IAC 400, 401, 402, and 417), and from RRIM 600 clone (used as a control in both cases). IAC 405 a...

  19. Seasonal and clonal variations in technological and thermal properties of raw Hevea natural rubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was undertaken over a ten-month period, under the environmental conditions within the state of Mato Grosso, Brazil, to evaluate the causes of variation in technological and thermal properties of raw natural rubber from different clones of Hevea brasiliensis (GT 1, PR 255, FX 3864 and RRIM...

  20. 21 CFR 801.437 - User labeling for devices that contain natural rubber.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., or by converting the sheets into a solution for dipping. (3) The term “contacts humans” means that... paragraphs (d) through (h) of this section. Each required labeling statement shall be prominently and legibly.... 352(c)). (d) Devices containing natural rubber latex that contacts humans, as described in...

  1. Composite of Natural Rubber Extracted from Guayule Reinforced with Cellulose Microfibers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this work composites of natural rubber extracted from Guayule (Parthenium argentatum) and cellulose microfibers, extracted from cotton fibers by acid hydrolysis, were obtained. The effects of the microfiber content on the mechanical properties of the composites were investigated by tensile tests ...

  2. FLOW PROPERTIES OF NATURAL RUBBER COMPOSITES FILLED WITH DEFATTED SOY FLOUR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previously, defatted soy flour (DSF) in a styrene-butadiene matrix has been shown to have a significant reinforcement effect. In this study, the objective is to investigate the flow properties of composites in natural rubber to understand their processing characteristics. Composites with 10 to 30 ...

  3. New phenylenediamine antiozonants for commodities based on natural and synthetic rubber.

    PubMed

    Krüger, R H; Boissiére, C; Klein-Hartwig, K; Kretzschmar, H-J

    2005-10-01

    For protection of elastomeric materials against ageing, antioxidants such as UV-stabilizers and antiozonants are used. Although historically N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (6PPD) was the only approved antiozonant in Germany, a range of other phenylene diamine antiozonants (excluding 6PPD) are permitted for use in rubber articles intended for repeat food-contact use in the US (FDA regulations chapter 21 Part 177.2600). The biggest disadvantage of 6PPD is its partial decomposition during the vulcanization leading to the formation of toxic primary aromatic amines (PAA), such as aniline and secondary aromatic amines (SAA). A number of new PPDs have been developed and patented, that due to their chemical structures, are far less soluble in aqueous solutions but a lot more soluble within the rubber matrix. They therefore show significantly less migration of PAA and SAA. These new antiozonants were investigated and compared to 6PPD using commercial rubber materials with a certain content of antiozonant with regard to their migration of PAA and SAA into three different food simulants. The lowest concentration of PAA and SAA in all food simulants was measured in the RU 997 stabilized elastomer. Due to this fact RU 997 was permitted as a new antiozonant for commodities based on rubber according to the Recommendation XXI 'Articles based on natural and synthetic rubber' of the Federal Institute for Risk Assessment (BfR). RU 997 therefore represents an alternative for 6PPD with less migration of aromatic amines. PMID:16227180

  4. 21 CFR 177.1635 - Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene). 177.1635 Section 177.1635 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic...

  5. 21 CFR 177.1635 - Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene). 177.1635 Section 177.1635 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic...

  6. 21 CFR 177.1635 - Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene). 177.1635 Section 177.1635 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic...

  7. Rubber modified and performance based asphalt binder pavements: I-5 Nisqually River to Gravelly Lake. Post construction report

    SciTech Connect

    Pierce, L.M.

    1996-01-01

    The report describes the construction of asphalt pavements made with three types of asphalt binders. The three types of binders were PBA-6, PBA-6GR (ground rubber), and AR4000W. The two modified binders, PBA-6 and PBA-6GR, are being evaluated to determine their resistance to rutting as compared to the conventional binder, AR4000W.

  8. Arsenite and arsenate removal from wastewater using cationic polymer-modified waste tyre rubber.

    PubMed

    Imyim, Apichat; Sirithaweesit, Thitayati; Ruangpornvisuti, Vithaya

    2016-01-15

    Waste tyre rubber (WTR) granulate was modified with a cationic polymer, poly(3-acrylamidopropyl)trimethylammonium chloride (p(APTMACl)). The resulting WTR/p(APTMACl) was utilized for the adsorption of arsenite, As(III) and arsenate, As(V) from aqueous medium in both batch and column methods. The level of adsorption increased gradually with increasing monomer concentration and contact time. The adsorption behavior obeyed the Freundlich model, and the rate of adsorption could be predicted by employing the pseudo-second order model. In the column method, As(V) could be adsorbed onto the sorbent more effectively than As(III). Remarkable desorption of As(III) and As(V) (99 and 92%, respectively) from the adsorbent was achieved using 0.10 M HCl as eluent. An approach of evaluation of adsorption capacity uncertainty is proposed. PMID:26607568

  9. Recycling Waste Natural Rubber Latex by Blending with Polystyrene - Characterization of Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Boondamnoen, O.; Ohshima, M.; Azura, A. R.; Chuayjuljit, S.; Ariffin, A.

    Waste natural rubber latex was blended with polystyrene (WNRL/PS) for recycling. A mixture with a 50/50 ratio of rubber to PS was blended by an internal mixer (Haake) at 140 °C and 60 rpm. The PS became the matrix, and the WNRL was dispersed within the matrix. Dynamically vulcanized natural rubber/PS (NRv/PS) blends and natural rubber/PS (NR/PS) blends without vulcanization were also prepared in the same way for comparison. The tensile properties and morphologies of all blends were investigated. The crosslinking density was determined by using the Flory-Rehner equation. The experiments showed that the WNRL/PS blend exhibited a higher tensile strength, Young's modulus and crosslinking density, but a lower elongation at break, than the NRv/PS and NR/PS blends. SEM observations of the tensile fracture surface and TEM observations of the blend morphology indicated that the WNRL/PS blend needed a higher energy to break than the NRv/PS and NR/PS blends.

  10. Nanocomposites prepared from acrylonitrile butadiene rubber and organically modified montmorillonite with vinyl groups

    NASA Astrophysics Data System (ADS)

    Han, Mijeong; Kim, Hoonjung; Kim, Eunkyoung

    2006-01-01

    Nanocomposites were prepared from acrylonitrile-butadiene rubber (NBR), vinyl groups containing organically modified montmorillonite and additives, such as zinc oxide, stearic acid, and sulfur. The organically modified montmorillonites used in these nanocomposites were prepared by ion exchange reactions of N,N'-dimethylalkyl-(p-vinylbenzyl)-ammonium chlorides (DAVBAs, alkyl = octyl, dodecyl, and octadecyl) with sodium montmorillonite (Na+-MMT). NBR nanocomposites were obtained by controlling both the mixing and vulcanization conditions, by using a Brabender mixer and hot-press process. X-ray diffraction (XRD) analysis shows that, depending on the amount of montmorillonite that is added, both exfoliated and intercalated nanocomposite structures are formed. The NBR/DAVBA-MMT nanocomposites exhibit much higher mechanical properties (e.g., tensile strength, Young's modulus, 300% modulus, and hardness) as well as gas barrier properties as compared to NBR Na+-MMT or NBR composites generated from modified montmorillonites without vinyl groups. Consistent with the results of XRD, transmission electron microscopy (TEM) reveals that the intercalation and exfoliation structures of the nanocomposites coexist and that the DAVBA-MMT layers are well dispersed in NBR.

  11. SUSTAINABILITY OF NATURAL RUBBER-PRODUCING CROPS IN THE UNITED STATES: APPLIED BIOTECHNOLOGY LESSONS 2000-2010

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber (NR) is a critical and strategic raw material for industrial manufacturing and national defense. Development of a US-based supply of NR is recognized in the Critical Agricultural Materials Act, Public Law 95–592. Domestic rubber-producing crops have been introduced in the US during ti...

  12. Reactivity of sulfide-containing silane toward boehmite and in situ modified rubber/boehmite composites by the silane

    NASA Astrophysics Data System (ADS)

    Lin, Tengfei; Zhu, Lixin; Chen, Weiwei; Wu, Siwu; Guo, Baochun; Jia, Demin

    2013-09-01

    The silanization reaction between boehmite (BM) nanoplatelets and bis-[3-(triethoxysilyl)-propyl]-tetrasulfide (TESPT) was characterized in detail. Via such modification process, the grafted sulfide moieties on the BM endow reactivity toward rubber and substantially improved hydrophobicity for BM. Accordingly, TESPT was employed as in situ modifier for the nitrile rubber (NBR)/BM compounds to improve the mechanical properties of the reinforced vulcanizates. The effects of BM content and in situ modification on the mechanical properties, curing characteristics and morphology were investigated. BM was found to be effective in improving the mechanical performance of NBR vulcanizates. The NBR/BM composites could be further strengthened by the incorporation of TESPT. The interfacial adhesion of NBR/BM composites was obviously improved by the addition of TESPT. The substantially improved mechanical performance was correlated to the interfacial reaction and the improved dispersion of BM in rubber matrix.

  13. Investigation of the deformation mechanisms of core-shell rubber-modified epoxy at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Brown, Hayley Rebecca

    The industrial demand for high strength-to-weight ratio materials is increasing due to the need for high performance components. Epoxy polymers, although often used in fiber-reinforced polymeric composites, have an inherent low toughness that further decreases with decreasing temperatures. Second-phase additives have been effective in increasing the toughness of epoxies at room temperature; however, the mechanisms at low temperatures are still not understood. In this study, the deformation mechanisms of a DGEBA epoxy modified with MX960 core-shell rubber (CSR) particles were investigated under quasi-static tensile and impact loads at room temperature (RT) and liquid nitrogen (LN 2) temperature. Overall, the CSR had little effect on the tensile properties at RT and LN2 temperature. The impact strength decreased from neat to 3 wt% but increased from neat to 5 wt% at RT and LN2 temperature, with a higher impact strength at RT at all CSR loadings. The CSR particles debonded in front of the crack tip, inducing voids into the matrix. It was found that an increase in shear deformation and void growth likely accounted for the higher impact strength at 5 wt% CSR loading at RT while the thermal stress fields due to the coefficient of thermal expansion mismatch between rubber and epoxy and an increase in secondary cracking is likely responsible for the higher impact strength at 5 wt% tested at LN2 temperature. While a large toughening effect was not seen in this study, the mechanisms analyzed herein will likely be of use for further material investigations at cryogenic temperatures.

  14. Fatigue behavior of rubber modified pavements. Final report, 1994-1996

    SciTech Connect

    Raad, L.; Saboundjian, S.

    1997-05-01

    Over the last 15 years, a number of rubberized pavement projects have been built in Alaska. Initial laboratory and field investigations sponsored by the Alaska Department of Transportation and Public Facilities (AKDOT&PF) and conducted by Raad et al. (1995) indicated improved fatigue performance of the rubberized sections in comparison with conventional asphalt concrete pavements. The report presents the results of a follow-up investigation to develop design equations for rubberized pavements in Alaska.

  15. A new method for in vivo evaluation of biofilms on surface-modified silicone rubber voice prostheses.

    PubMed

    Everaert, E P; Mahieu, H F; Wong Chung, R P; Verkerke, G J; van der Mei, H C; Busscher, H J

    1997-01-01

    A new method is presented that permits a rapid and accurate in vivo evaluation of biofilm formation on surface-modified silicone rubber voice prostheses. The method is based on partial modification of a Groningen button voice prosthesis by exposing half of the prosthesis to an argon plasma. This results in one side of the prosthesis becoming hydrophilic while leaving the unmodified side hydrophobic as a control. Modified prostheses were placed in patients for an evaluation period of approximately 4 weeks. Despite making the silicone rubber surface hydrophilic, biofilm formation was stimulated when compared to unmodified, hydrophobic silicone rubber. Findings show that biofilm formation on voice prostheses is influenced by hydrophobicity of a silicone rubber surface. The method of partial surface modification used was seen to be suitable for demonstrating such influences regardless of nutrition and other variations in the patient's lifestyle. Microbiological analysis of the biofilms on both sides of the prosthesis valve did not show any changes in microbial composition, with Candida albicans, streptococci and staphylococci being the most commonly isolated strains. PMID:9248731

  16. A study of the influence of micro and nano phase morphology on the mechanical properties of a rubber-modified epoxy resin

    NASA Astrophysics Data System (ADS)

    Russell, Bobby Glenn

    Epoxy resins are thermosets with extraordinary adhesion; high strength; good resistance to creep, heat, and chemicals; and they have low shrinkage. Conversely, these polymers are brittle, they are sensitive to moisture, and they exhibit poor toughness. To improve their toughness, they are often modified by introducing dispersed rubber particles in the primary phase. In this study, the epoxy resin was modified with carboxyl-terminated butadiene acrylonitrile (CTBN), liquid-reactive rubbers. The initiator concentration, percent acrylonitrile in the CTBN rubber, and cure temperatures were altered to give varying materials properties. Statistical analysis of the morphology data showed that the percentage of rubber acrylonitrile had an effect on both the rubber particle size and volume fraction. The cure temperature had an effect on the rubber particle volume and modulus. Plots of the rubber particle size, volume fraction, and modulus versus bulk elastic storage modulus and fracture toughness revealed that rubber particle size had no effect on bulk properties, volume fraction and rubber particle modulus had an effect on both the bulk storage elastic modulus and fracture toughness.

  17. Effect of epoxidation on 30% poly(methyl methacrylate)-grafted natural rubber polymer electrolytes

    SciTech Connect

    Nazir, Khuzaimah; Aziz, Ahmad Fairoz; Adam, Nurul Ilham; Yahya, Muhd Zu Azhan; Ali, Ab Malik Marwan

    2015-08-28

    Epoxidized 30% poly(methyl methacrylate)-grafted natural rubber (EMG 30) as a polymer host in solid polymer electrolytes (SPEs) has been investigated. EMG30 was synthesized via performicepoxidation method onto 30% poly(methyl methacrylate)-grafted natural rubber (MG30) and the formations of epoxy group were discussed. The EMG30 were characterized by proton nuclear magnetic resonance ({sup 1}HNMR) to investigate their chemical structure and differential scanning calorimeter to determine their crystallinity. A new peak in {sup 1}HNMR spectra (2.71 ppm) confirmed the appearance of epoxy group. SPE based on EMG30 doped with 40 wt% LiCF{sub 3}SO{sub 3} show the highest conductivity. The complexation between EMG30 and LiCF{sub 3}SO{sub 3} were confirmed by attenuated total reflection Fourier transform infrared (ATR-FTIR)

  18. Effect of epoxidation on 30% poly(methyl methacrylate)-grafted natural rubber polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Nazir, Khuzaimah; Aziz, Ahmad Fairoz; Adam, Nurul Ilham; Yahya, Muhd Zu Azhan; Ali, Ab Malik Marwan

    2015-08-01

    Epoxidized 30% poly(methyl methacrylate)-grafted natural rubber (EMG 30) as a polymer host in solid polymer electrolytes (SPEs) has been investigated. EMG30 was synthesized via performicepoxidation method onto 30% poly(methyl methacrylate)-grafted natural rubber (MG30) and the formations of epoxy group were discussed. The EMG30 were characterized by proton nuclear magnetic resonance (1HNMR) to investigate their chemical structure and differential scanning calorimeter to determine their crystallinity. A new peak in 1HNMR spectra (2.71 ppm) confirmed the appearance of epoxy group. SPE based on EMG30 doped with 40 wt% LiCF3SO3 show the highest conductivity. The complexation between EMG30 and LiCF3SO3 were confirmed by attenuated total reflection Fourier transform infrared (ATR-FTIR).

  19. Epoxidized natural rubber toughened aqueous resole type liquefied EFB resin: Physical and chemical characterization

    NASA Astrophysics Data System (ADS)

    Amran, Umar Adli; Zakaria, Sarani; Chia, Chin Hua

    2013-11-01

    A preliminary study on the reaction between aqueous resole type resinified liquefied palm oil empty fruit bunches fibres (RLEFB) with epoxidized natural rubber (ENR). Liquefaction of empty fruit bunches (EFB) is carried out at different ratio of phenol to EFB (P:EFB). Resole type phenolic resin is prepared using sodium hydroxide (NaOH) as the catalyst with the ratio of liquefied EFB (LEFB) to formaldehyde (LEFB:F) of 1:1.8. 50% epoxidation of epoxidized natural rubber (ENR-50) is used to react with resole resin by mixing with ENR with aqueous resole resin. The cured resin is characterized with FT-IR and SEM. Aqueous system have been found to be unsuitable medium in the reaction between resin and ENR. This system produced a highly porous product when RLEFB/ENR resin is cured.

  20. Physical-biopolymer characterization of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) blended with natural rubber latex

    NASA Astrophysics Data System (ADS)

    Kuntanoo, K.; Promkotra, S.; Kaewkannetra, P.

    2015-03-01

    A biopolymer of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is blended with bio-based materials, natural rubber latex, to improve their microstructures. The various ratios between PHBV and natural rubber latex are examined to develop their mechanical properties. In general, physical properties of PHBV are hard, brittle and low flexible while natural rubber (NR) is presented itself as high elastic materials. Concentrations of the PHBV solution are constituted at 1%, 2% and 3% (w/v). The mixtures of their PHBV solutions to natural rubber latex are produced the blended films in three different ratios of 4:6, 5:5 and 6:4, respectively. They are characterized by appearance analyses which are the scanning electron microscope (SEM), universal testing machine (UTM) and differential scanning calorimetry (DSC). The SEM photomicrographs of the blended films and the controlled PHBV can provide the void distribution in the range of 12-14% and 19-21%, respectively. For mechanical properties of the blended films, the various elastic moduli of 1%, 2% and 3% (w/v) PHBV are the average of 773, 956 and 1,007 kPa, respectively. The tensile strengths of the blends increase with the increased concentrations of PHBV, similarly trend to the elastic modulus. The crystallization and melting behavior of unmixed PHBV and the blends are determined by DSC. Melting transition temperatures (Tm) of the unmixed PHBV are stated two melting peak at 154°C and 173°C. Besides, the melting peaks of the blends alter in the range of 152-156°C and 168-171°C, respectively. According to morphology of the blends, the void distribution decreases twice compared to the unmixed PHBV. The results of mechanical properties and thermal analysis indicate that the blended PHBV can be developed their properties by more resilient and wide range of temperature than usual.

  1. A Micro-Mechanically Based Continuum Model for Strain-Induced Crystallization in Natural Rubber

    NASA Astrophysics Data System (ADS)

    Mistry, Sunny Jigger

    Recent experimental results show that strain-induced crystallization can substantially improve the crack growth resistance of natural rubber. While this might suggest superior designs of tires or other industrial applications where elastomers are used, a more thorough understanding of the underlying physics of strain-induced crystallization in natural rubber has to be developed before any design process can be started. The objective of this work is to develop a computationally-accessible micro-mechanically based continuum model, which is able to predict the macroscopic behavior of strain crystallizing natural rubber. While several researchers have developed micro-mechanical models of partially crystallized polymer chains, their results mainly give qualitative agreement with experimental data due to a lack of good micro-macro transition theories or the lack of computational power. However, recent developments in multiscale modeling in polymers provide new tools to continue this early work. In this thesis, a new model is proposed to model strain-induced crystallization in natural rubber. To this end, a micro-mechanical model of a constrained partially crystallized polymer chain with an extended-chain crystal is derived and connected to the macroscopic level using the non-affine micro-sphere model. On the macroscopic level, a thermodynamically consistent framework for strain-crystallizing materials is developed, and a description of the crystallization kinetics is introduced. For that matter, an evolution law for crystallization based on the gradient of the macroscopic Helmholtz free energy function (chemical potential) in combination with a simple threshold function is used. A numerical implementation of the model is proposed and its predictive performance assessed using published data.

  2. Physical-biopolymer characterization of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) blended with natural rubber latex

    SciTech Connect

    Kuntanoo, K.; Promkotra, S.; Kaewkannetra, P.

    2015-03-30

    A biopolymer of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is blended with bio-based materials, natural rubber latex, to improve their microstructures. The various ratios between PHBV and natural rubber latex are examined to develop their mechanical properties. In general, physical properties of PHBV are hard, brittle and low flexible while natural rubber (NR) is presented itself as high elastic materials. Concentrations of the PHBV solution are constituted at 1%, 2% and 3% (w/v). The mixtures of their PHBV solutions to natural rubber latex are produced the blended films in three different ratios of 4:6, 5:5 and 6:4, respectively. They are characterized by appearance analyses which are the scanning electron microscope (SEM), universal testing machine (UTM) and differential scanning calorimetry (DSC). The SEM photomicrographs of the blended films and the controlled PHBV can provide the void distribution in the range of 12-14% and 19-21%, respectively. For mechanical properties of the blended films, the various elastic moduli of 1%, 2% and 3% (w/v) PHBV are the average of 773, 956 and 1,007 kPa, respectively. The tensile strengths of the blends increase with the increased concentrations of PHBV, similarly trend to the elastic modulus. The crystallization and melting behavior of unmixed PHBV and the blends are determined by DSC. Melting transition temperatures (T{sub m}) of the unmixed PHBV are stated two melting peak at 154°C and 173°C. Besides, the melting peaks of the blends alter in the range of 152-156°C and 168-171°C, respectively. According to morphology of the blends, the void distribution decreases twice compared to the unmixed PHBV. The results of mechanical properties and thermal analysis indicate that the blended PHBV can be developed their properties by more resilient and wide range of temperature than usual.

  3. Mechanical and Magnetic Properties of Thermoplastic Natural Rubber Nanocomposites Filled with Barium Ferrit

    NASA Astrophysics Data System (ADS)

    Milad, Mohamed M. M.; Ahmad, Sahrim Hj.; Yahya, S. Y.; Tarawneh, Mou'ad. A.

    2009-06-01

    This study was undertaken to investigate the mechanical and magnetic properties of thermoplastic natural rubber (TPNR) filled with barium ferrite BaFe12O19 nanoparticle. The nanocompasites were prepared via melt blending method using the Haake 600 p internal mixer. The content of the filler is varied from 2-10% by volume fraction. TPNR is a blend of polypropylene (PP), liquid natural rubber (LNR) and natural rubber (NR) at the percentage of volume ratio 70:10:20. The nanocomposites were prepared at 180° C with mixing speed 110 and 13 min mixing time. Tensile properties of the samples were measured using a universal machine, Tensometric 500. The results show that TPNR nanocomposites with only 4% nanoparticles exhibited good mechanical properties. The improvements were about 23.7% for tensile strength 20.1% for Young's modulus and 11.16% for strain respectively. The magnetic properties of TPNR filled nanoparticles was studied using vibrating sample magnetometer (VSM) at room temperature and it was found that magnetization (Ms), and remanent magnetization (Mr) increased with increasing ferrite content.

  4. Super-hydrophobicity and oleophobicity of silicone rubber modified by CF 4 radio frequency plasma

    NASA Astrophysics Data System (ADS)

    Gao, Song-Hua; Gao, Li-Hua; Zhou, Ke-Sheng

    2011-03-01

    Owing to excellent electric properties, silicone rubber (SIR) has been widely employed in outdoor insulator. For further improving its hydrophobicity and service life, the SIR samples are treated by CF 4 radio frequency (RF) capacitively coupled plasma. The hydrophobic and oleophobic properties are characterized by static contact angle method. The surface morphology of modified SIR is observed by atom force microscope (AFM). X-ray photoelectron spectroscopy (XPS) is used to test the variation of the functional groups on the SIR surface due to the treatment by CF 4 plasma. The results indicate that the static contact angle of SIR surface is improved from 100.7° to 150.2° via the CF 4 plasma modification, and the super-hydrophobic surface of modified SIR, which the corresponding static contact angle is 150.2°, appears at RF power of 200 W for a 5 min treatment time. It is found that the super-hydrophobic surface ascribes to the coaction of the increase of roughness created by the ablation action and the formation of [-SiF x(CH 3) 2- x-O-] n ( x = 1, 2) structure produced by F atoms replacement methyl groups reaction, more importantly, the formation of [-SiF 2-O-] n structure is the major factor for super-hydrophobic surface, and it is different from the previous studies, which proposed the fluorocarbon species such as C-F, C-F 2, C-F 3, CF-CF n, and C-CF n, were largely introduced to the polymer surface and responsible for the formation of low surface energy.

  5. Novel Slide-Ring Material/Natural Rubber Composites with High Damping Property.

    PubMed

    Wang, Wencai; Zhao, Detao; Yang, Jingna; Nishi, Toshio; Ito, Kohzo; Zhao, Xiuying; Zhang, Liqun

    2016-01-01

    A novel class of polymers called "slide-ring" (SR) materials with slideable junctions were used for high damping composites for the first time. The SR acts as the high damping phase dispersed in the natural rubber (NR) matrix, and epoxidized natural rubber (ENR) acts as the compatibilizer. The morphological, structural, and mechanical properties of the composites were investigated by atomic force microscope (AFM), transmission electron microscope (TEM), dynamic mechanical thermal analyzer (DMTA), rubber processing analyzer (RPA), and tensile tester. AFM and TEM results showed that the SR phase was uniformly dispersed in the composites, in a small size that is a function of ENR. DMTA and RPA results showed that the damping factor of the composites is much higher than that of NR, especially at room temperatures. Stretch hysteresis was used to study the energy dissipation of the composites at large strains. The results showed that SR and ENR can significantly improve the dissipation efficiency at strains lower than 200% strain. Wide-angle X-ray diffraction was used to study the strain-induced crystallization of the composites. The results indicated that the impact of the SR on the crystallization of NR is mitigated by the insulating effect of ENR. PMID:26949077

  6. Novel Slide-Ring Material/Natural Rubber Composites with High Damping Property

    NASA Astrophysics Data System (ADS)

    Wang, Wencai; Zhao, Detao; Yang, Jingna; Nishi, Toshio; Ito, Kohzo; Zhao, Xiuying; Zhang, Liqun

    2016-03-01

    A novel class of polymers called “slide-ring” (SR) materials with slideable junctions were used for high damping composites for the first time. The SR acts as the high damping phase dispersed in the natural rubber (NR) matrix, and epoxidized natural rubber (ENR) acts as the compatibilizer. The morphological, structural, and mechanical properties of the composites were investigated by atomic force microscope (AFM), transmission electron microscope (TEM), dynamic mechanical thermal analyzer (DMTA), rubber processing analyzer (RPA), and tensile tester. AFM and TEM results showed that the SR phase was uniformly dispersed in the composites, in a small size that is a function of ENR. DMTA and RPA results showed that the damping factor of the composites is much higher than that of NR, especially at room temperatures. Stretch hysteresis was used to study the energy dissipation of the composites at large strains. The results showed that SR and ENR can significantly improve the dissipation efficiency at strains lower than 200% strain. Wide-angle X-ray diffraction was used to study the strain-induced crystallization of the composites. The results indicated that the impact of the SR on the crystallization of NR is mitigated by the insulating effect of ENR.

  7. Novel Slide-Ring Material/Natural Rubber Composites with High Damping Property

    PubMed Central

    Wang, Wencai; Zhao, Detao; Yang, Jingna; Nishi, Toshio; Ito, Kohzo; Zhao, Xiuying; Zhang, Liqun

    2016-01-01

    A novel class of polymers called “slide-ring” (SR) materials with slideable junctions were used for high damping composites for the first time. The SR acts as the high damping phase dispersed in the natural rubber (NR) matrix, and epoxidized natural rubber (ENR) acts as the compatibilizer. The morphological, structural, and mechanical properties of the composites were investigated by atomic force microscope (AFM), transmission electron microscope (TEM), dynamic mechanical thermal analyzer (DMTA), rubber processing analyzer (RPA), and tensile tester. AFM and TEM results showed that the SR phase was uniformly dispersed in the composites, in a small size that is a function of ENR. DMTA and RPA results showed that the damping factor of the composites is much higher than that of NR, especially at room temperatures. Stretch hysteresis was used to study the energy dissipation of the composites at large strains. The results showed that SR and ENR can significantly improve the dissipation efficiency at strains lower than 200% strain. Wide-angle X-ray diffraction was used to study the strain-induced crystallization of the composites. The results indicated that the impact of the SR on the crystallization of NR is mitigated by the insulating effect of ENR. PMID:26949077

  8. Monitoring Network and Interfacial Healing Processes by Broadband Dielectric Spectroscopy: A Case Study on Natural Rubber.

    PubMed

    Hernández, M; Grande, A M; van der Zwaag, S; García, S J

    2016-04-27

    Broadband dielectric spectroscopy (BDS) is introduced as a new and powerful technique to monitor network and macroscale damage healing in an elastomer. For the proof of concept, a partially cured sulfur-cured natural rubber (NR) containing reversible disulfides as the healing moiety was employed. The forms of damage healed and monitored were an invisible damage in the rubber network due to multiple straining and an imposed macroscopic crack. The relaxation times of pristine, damaged, and healed samples were determined and fitted to the Havriliak-Negami equation to obtain the characteristic polymer parameters. It is shown that seemingly full mechanical healing occurred regardless the type of damage, while BDS demonstrates that the polymer architecture in the healed material differs from that in the original one. These results represent a step forward in the understanding of damage and healing processes in intrinsic self-healing polymer systems with prospective applications such as coatings, tires, seals, and gaskets. PMID:27057588

  9. Nanocelluloses from jute fibers and their nanocomposites with natural rubber: Preparation and characterization.

    PubMed

    Thomas, Martin George; Abraham, Eldho; Jyotishkumar, P; Maria, Hanna J; Pothen, Laly A; Thomas, Sabu

    2015-11-01

    Nanocellulose fibers having an average diameter of 50nm were isolated from raw jute fibers by steam explosion process. The isolation of nanocellulose from jute fibers by this extraction process is proved by SEM, XRD, FTIR, birefringence and TEM characterizations. This nanocellulose was used as the reinforcing agent in natural rubber (NR) latex along with crosslinking agents to prepare crosslinked nanocomposite films. The effects of nanocellulose loading on the morphology and mechanics of the nanocomposites have been carefully analyzed. Significant improvements in the Young's modulus and tensile strength of the nanocomposite were observed because of the reinforcing ability of the nanocellulose in the rubber matrix. A mechanism is suggested for the formation of the Zn-cellulose complex. The three-dimensional network of cellulose nanofibers (cellulose/cellulose network and Zn/cellulose network) in the NR matrix plays a major role in improving the properties of the crosslinked nanocomposites. PMID:26318667

  10. Surface morphology changes of lignin filled natural rubber latex films investigated using AFM in relation to tensile strengths

    NASA Astrophysics Data System (ADS)

    Asrul, M.; Othman, M.; Zakaria, M.

    2015-07-01

    The paper describes the preparation of lignin filled natural rubber latex composite and the consequential changes in tensile strength observed with varying lignin loading. The changes in tensile strength were shown to be associated with the changes in surface morphology as investigated via AFM. From the AFM analysis it can be inferred that lignin filled rubber latex film which exhibited an increase in tensile strength also demonstrated better phase homogeneity with lowest surface roughness value in comparison to the rest of the lignin filled rubber latex films analysed.

  11. Rubber-based substrates modified with carbon nanotubes inks to build flexible electrochemical sensors.

    PubMed

    Cuartero, María; del Río, Jonathan Sabaté; Blondeau, Pascal; Ortuño, Joaquín A; Rius, F Xavier; Andrade, Francisco J

    2014-05-27

    The development of a solid-contact potentiometric sensor based on conducting rubbers using a carbon nanotubes ink is described here. Commercial rubbers are turned into conductive ones by a simple and versatile method, i.e. painting an aqueous dispersion of single-walled carbon nanotubes on the polymer surface. On this substrate, both the working ion-selective electrode and the reference electrode are built in order to form an integrated potentiometric cell. As a proof-of-principle, selective potassium electrodes are fully characterized giving comparable performances to conventional electrodes (sensitivity, selectivity, stability, linear range, limit of detection and reproducibility). As an application of the rubber-based electrodes, a bracelet was constructed to measure potassium levels in artificial sweat. Since rubbers are ubiquitous in our quotidian life, this approach offers great promise for the generation of chemical information through daily objects. PMID:24833000

  12. Surface modification of halloysite nanotubes by vulcanization accelerator and properties of styrene-butadiene rubber nanocomposites with modified halloysite nanotubes

    NASA Astrophysics Data System (ADS)

    Zhong, Bangchao; Jia, Zhixin; Hu, Dechao; Luo, Yuanfang; Guo, Baochun; Jia, Demin

    2016-03-01

    Vulcanization accelerant N-cyclohexyl-2-benzothiazole sulfenamide (CZ) was used as a surface modifier and chemically grafted on the surface of halloysite nanotubes (HNTs) to obtain CZ-functionalized HNTs (HNTs-s-CZ). It was found that HNTs-s-CZ could be homogeneously dispersed into styrene-butadiene rubber (SBR). The grafted CZ molecules, exactly located at the filler-rubber interface, reduced the activation energy of vulcanization of SBR/HNTs-s-CZ compounds. Besides, the density of chain segments introduced by the interfacial phase of SBR/HNTs-s-CZ nanocomposites was higher than the other nanocomposites with silane-modified HNTs (m-HNTs) or pristine HNTs, manifesting an indication of enhanced filler-rubber interfacial interaction in SBR/HNTs-s-CZ nanocomposites. Consequently, SBR/HNTs-s-CZ nanocomposites showed excellent mechanical properties. The tensile strength could be enhanced by as much as 38.6% and 102.5% compared to those of SBR/m-HNTs and SBR/HNTs nanocomposites, respectively, though containing equivalent accelerant component. The value of this work lies in the fact that apparent properties improvement of elastomer composites has been achieved by the incorporation of vulcanization accelerant-functionalized HNTs, which may be fruitful for the rational design of filler surface treatment and offer new scientific and technological opportunities for the preparation of high performance elastomer composites.

  13. Allergic contact urticaria from natural rubber latex in healthcare and non-healthcare workers.

    PubMed

    Valks, Ruud; Conde-Salazar, Luis; Cuevas, Manuela

    2004-04-01

    To compare the prevalence of natural rubber latex (NRL) sensitization and allergic contact urticaria from NRL in healthcare and non-healthcare workers, we studied all 1171 patients who attended our clinic during 2001 and 2002. Prick testing for NRL and patch testing with European standard series were performed in all patients and an additional rubber series in those who had contact with rubber. Specific immunoglobulin E (IgE) levels against NRL and tropical fruits were measured when prick testing was positive. Sensitization to NRL (positive prick test and specific IgE levels) was much more common in healthcare workers than that in non-healthcare workers, 16.7 versus 2.3%. Among the non-healthcare workers, sensitization to NRL was more common in food handlers (17.1%), construction workers (6.6%), painters (6.2%), hairdressers (5.1%) and cleaners (3.8%). The difference in the prevalence of specific IgE to tropical fruits was not significant. Allergic contact urticaria from NRL was also much more frequent in healthcare workers, 71.4 versus 28.6%. In conclusion, sensitization to NRL and allergic contact urticaria from NRL are more common in healthcare workers, but this is a growing problem in non-healthcare workers and should be investigated in all workers with a history of NRL intolerance or who have contact with NRL. PMID:15186377

  14. Identification of laticifer-specific genes and their promoter regions from a natural rubber producing plant Hevea brasiliensis.

    PubMed

    Aoki, Yuichi; Takahashi, Seiji; Takayama, Daisuke; Ogata, Yoshiyuki; Sakurai, Nozomu; Suzuki, Hideyuki; Asawatreratanakul, Kasem; Wititsuwannakul, Dhirayos; Wititsuwannakul, Rapepun; Shibata, Daisuke; Koyama, Tanetoshi; Nakayama, Toru

    2014-08-01

    Latex, the milky cytoplasm of highly differentiated cells called laticifers, from Hevea brasiliensis is a key source of commercial natural rubber production. One way to enhance natural rubber production would be to express genes involved in natural rubber biosynthesis by a laticifer-specific overexpression system. As a first step to identify promoters which could regulate the laticifer-specific expression, we identified random clones from a cDNA library of H. brasiliensis latex, resulting in 4325 expressed sequence tags (ESTs) assembled into 1308 unigenes (692 contigs and 617 singletons). Quantitative analyses of the transcription levels of high redundancy clones in the ESTs revealed genes highly and predominantly expressed in laticifers, such as Rubber Elongation Factor (REF), Small Rubber Particle Protein and putative protease inhibitor proteins. HRT1 and HRT2, cis-prenyltransferases involved in rubber biosynthesis, was also expressed predominantly in laticifers, although these transcript levels were 80-fold lower than that of REF. The 5'-upstream regions of these laticifer-specific genes were cloned and analyzed in silico, revealing seven common motifs consisting of eight bases. Furthermore, transcription factors specifically expressed in laticifers were also identified. The common motifs in the laticifer-specific genes and the laticifer-specific transcription factors are potentially involved in the regulation of gene expression in laticifers. PMID:25017153

  15. Modeling the temperature dependence of N-methylpyrrolidone permeation through butyl- and natural-rubber gloves.

    PubMed

    Zellers, E T; Sulewski, R

    1993-09-01

    This paper describes the temperature dependence of N-methylpyrrolidone (NMP) permeation through gloves used in microelectronics fabrication facilities. One type of butyl-rubber glove (North B161), two types of natural-rubber gloves (Edmont Puretek and Ansell Pacific White), and a natural rubber/nitrile/neoprene-blend glove (Pioneer Trionic) were tested at four temperatures from 25-50 degrees C using the ASTM F739-85 permeation test method. The butyl-rubber glove showed no breakthrough after four hours of exposure at any temperature. The variations with temperature of measured breakthrough times (BT) and steady-state permeation rates (SSPR) for the other gloves were described well by Arrhenius relationships, with BT values decreasing by factors of 7-10 and SSPR values increasing by factors of 4-6 over the temperature range studied. Extrapolation to 70 and 93 degrees C, the temperatures at which degreasing is often performed, yielded BT values of < 2 min and < 0.5 min, respectively, in all cases. With the exception of the butyl-rubber glove, following an initial exposure at 25 degrees C and air drying overnight, low levels of NMP vapor were detected off-gassing from the inner surfaces of the gloves. Experimental results were then compared to those expected from several permeation models. Estimates of the equilibrium solvent solubility, S, were calculated using a model based on three-dimensional solubility parameters. Estimates of the solvent diffusion coefficient, D, were obtained from correlations with either the solvent kinematic viscosity or the product of the Flory interaction parameter, chi, and the solvent molar volume. Combining these values of D and S in Fickian diffusion equations gave modeled BT estimates that were within 23% of experimental values over the temperature range examined. Modeled SSPR values were within 50% (typically within 25%) of experimental values. Another model based on a generalized Arrhenius relationship also provided useful but

  16. Investigations on permeation of mitomycin C through double layers of natural rubber gloves.

    PubMed

    Korinth, Gintautas; Schmid, Klaus; Midasch, Oliver; Boettcher, Melanie I; Angerer, Jürgen; Drexler, Hans

    2007-10-01

    Treating peritoneal carcinomatosis by the aggressive cytoreductive surgery with the hyperthermic intraoperative intraperitoneal chemotherapy (HIPEC) surgeons expose their gloved hands for up to 90 min to a peritoneal dialysis solution (PDS) containing mitomycin C (MMC). We investigated the permeation of MMC through the material of three different natural rubber gloves under conditions similar to the in-use during HIPEC as well as under worst-case exposure scenario. Two different methods, a two-chamber diffusion cell and a single-chamber glass chamber method, were used to demonstrate the permeation capability. The permeation of MMC dissolved in 0.9% NaCl solution and PDS through double natural rubber glove material was tested over 2 h using four concentrations (c = 0.004, 0.008, 0.016 and 0.4 mg ml(-1)) and three receptor fluids (0.9% NaCl solution, PDS and a novel artificial sweat). In none of four glass chamber experiments and in only one of 40 diffusion cell experiments was permeation through glove material detected. The permeation occurred between 15 and 30 min under worst-case exposure scenario at a approximately 100-fold higher MMC concentration than under in-use conditions during HIPEC. The double-layer natural rubber gloves tested were effective to prevent a permeation of MMC in vitro under HIPEC-similar exposure. Our results support the glove wearing procedure in our university hospital. However, occupational exposure to antineoplastic drugs should be minimized, since there is insufficient knowledge regarding harmful effects from a long-term exposure to low doses. PMID:17921240

  17. Attenuation of foot pressure during running on four different surfaces: asphalt, concrete, rubber, and natural grass.

    PubMed

    Tessutti, Vitor; Ribeiro, Ana Paula; Trombini-Souza, Francis; Sacco, Isabel C N

    2012-01-01

    The practice of running has consistently increased worldwide, and with it, related lower limb injuries. The type of running surface has been associated with running injury etiology, in addition other factors, such as the relationship between the amount and intensity of training. There is still controversy in the literature regarding the biomechanical effects of different types of running surfaces on foot-floor interaction. The aim of this study was to investigate the influence of running on asphalt, concrete, natural grass, and rubber on in-shoe pressure patterns in adult recreational runners. Forty-seven adult recreational runners ran twice for 40 m on all four different surfaces at 12 ± 5% km · h(-1). Peak pressure, pressure-time integral, and contact time were recorded by Pedar X insoles. Asphalt and concrete were similar for all plantar variables and pressure zones. Running on grass produced peak pressures 9.3% to 16.6% lower (P < 0.001) than the other surfaces in the rearfoot and 4.7% to 12.3% (P < 0.05) lower in the forefoot. The contact time on rubber was greater than on concrete for the rearfoot and midfoot. The behaviour of rubber was similar to that obtained for the rigid surfaces - concrete and asphalt - possibly because of its time of usage (five years). Running on natural grass attenuates in-shoe plantar pressures in recreational runners. If a runner controls the amount and intensity of practice, running on grass may reduce the total stress on the musculoskeletal system compared with the total musculoskeletal stress when running on more rigid surfaces, such as asphalt and concrete. PMID:22897427

  18. Nanolipoprotein particles comprising a natural rubber biosynthetic enzyme complex and related products, methods and systems

    DOEpatents

    Hoeprich, Paul D.; Whalen, Maureen

    2016-04-05

    Provided herein are nanolipoprotein particles that comprise a biosynthetic enzyme more particularly an enzyme capable of catalyzing rubber or other rubbers polymerization, and related assemblies, devices, methods and systems.

  19. The influence of molybdenum disulfide nanoplatelets on the dispersion of nano silica in natural rubber composites

    NASA Astrophysics Data System (ADS)

    Weng, Peijin; Wei, Qiuyan; Tang, Zhenghai; Lin, Tengfei; Guo, Baochun

    2015-12-01

    The dispersion of nanofiller in polymer composites is critical in governing the ultimate performances. Present study aimed to improve the dispersion of silica in elastomeric materials based on natural rubber (NR) composites using the nanoplatelets of molybdenum disulfide (MoS2), a graphene-like layered inorganic. NR latex was co-coagulated with MoS2 suspension to form NR/MoS2 compounds (1∼5 phr). Then silica (30 phr) was incorporated into NR/MoS2 compounds, followed by curing with sulfur, to obtained NR/MoS2/silica composites. The dispersion state of silica in the composites was examined by TEM and the effects of MoS2 on the performance of the composites were investigated. It was found that a small amount of MoS2 nanoplatelets significantly improved the silica dispersion. Consequently, the static and dynamic mechanical properties of the crosslinked natural rubber materials were greatly enhanced. The improved dispersion of silica is associated with charge transfer interaction, giving rise to electrostatic repulsion among silica.

  20. Green synthesis of colloidal silver nanoparticles using natural rubber latex extracted from Hevea brasiliensis

    NASA Astrophysics Data System (ADS)

    Guidelli, Eder José; Ramos, Ana Paula; Zaniquelli, Maria Elisabete D.; Baffa, Oswaldo

    2011-11-01

    Colloidal silver nanoparticles were synthesized by an easy green method using thermal treatment of aqueous solutions of silver nitrate and natural rubber latex (NRL) extracted from Hevea brasiliensis. The UV-Vis spectra detected the characteristic surface plasmonic absorption band around 435 nm. Both NRL and AgNO 3 contents in the reaction medium have influence in the Ag nanoparticles formation. Lower AgNO 3 concentration led to decreased particle size. The silver nanoparticles presented diameters ranging from 2 nm to 100 nm and had spherical shape. The selected area electron diffraction (SAED) patterns indicated that the silver nanoparticles have face centered cubic (fcc) crystalline structure. FTIR spectra suggest that reduction of the silver ions are facilitated by their interaction with the amine groups from ammonia, which is used for conservation of the NRL, whereas the stability of the particles results from cis-isoprene binding onto the surface of nanoparticles. Therefore natural rubber latex extracted from H. brasiliensis can be employed in the preparation of stable aqueous dispersions of silver nanoparticles acting as a dispersing and/or capping agent. Moreover, this work provides a new method for the synthesis of silver nanoparticles that is simple, easy to perform, pollutant free and inexpensive.

  1. Preparation of antibacterial composite material of natural rubber particles coated with silica and titania

    NASA Astrophysics Data System (ADS)

    Wisutiratanamanee, Apisit; Poompradub, Sirilux; Poochinda, Kunakorn

    2014-06-01

    Silica coating, followed by titania coating, was performed over spray-dried natural rubber (NR) compound for physical and anti-bacterial characterizations. Titania has a strong photo-oxidative catalytic property, which can disinfect bacteria, but may degrade NR. Therefore, silica coating was intended to form a barrier between NR and titania. First, NR particles were prepared by spray-drying of NR compound latex, formulated for household glove products, mixed with sodium dodecyl sulfate (SDS) to reduce particle agglomeration. The factorial experimental design was employed to investigate the effects of nozzle flow rate (500-700 Lh-1), inlet air temperature (110-150 °C), SDS content (35-55 phr) and mass flow rate (1.2-1.7 g rubber/min) on NR yield and moisture content. Then, the NR compound particles prepared at the optimum condition were coated with silica, using tetraethoxysilane (TEOS) as the precursor, by chemical vapor deposition (CVD) at 60 °C for 2-48 hours. Next, the particles were coated with titania using titanium tetrafluoride (TiF4) by liquid phase deposition (LPD) at 60 ºC for 4-8 hours. The NR composites were characterized for surface morphology by SEM, silica and titania content by TGA and EDX. The NR composites were found to cause more than 99% reduction of Escherichia coli and Staphylococcus aureus under 1-hour exposure to natural light.

  2. The improvement in functional characteristics of eco-friendly composites made of natural rubber and cellulose

    SciTech Connect

    Araki, Kunihiro; Kaneko, Shonosuke; Matsumoto, Koki; Tanaka, Tatsuya; Arao, Yoshihiko; Nagatani, Asahiro

    2015-05-22

    We investigated the efficient use of cellulose to resolve the problem of the depletion of fossil resources. In this study, as the biomass material, the green composite based on natural rubber (NR) and the flake-shaped cellulose particles (FSCP) was produced. In order to further improvement of functional characteristics, epoxidized natural rubber (ENR) was also used instead of NR. The FSCP were produced by mechanical milling in a planetary ball mill with a grinding aid as a cellulose aggregation inhibitor. Moreover, talc and mica particles were used to compare with FSCP. NR and ENR was mixed with vulcanizing agents and then each filler was added to NR compound in an internal mixer. The vulcanizing agents are as follows: stearic acid, zinc oxide, sulfur, and vulcanization accelerator. The functionalities of the composites were evaluated by a vibration-damping experiment and a gas permeability experiment. As a result, we found that FSCP filler has effects similar to (or more than) inorganic filler in vibration-damping and O{sub 2} barrier properties. And then, vibration- damping and O{sub 2} barrier properties of the composite including FSCP was increased with use of ENR. In particular, we found that ENR-50 composite containing 50 phr FSCP has three times as high vibration-damping property as ENR-50 without FSCP.

  3. The improvement in functional characteristics of eco-friendly composites made of natural rubber and cellulose

    NASA Astrophysics Data System (ADS)

    Araki, Kunihiro; Kaneko, Shonosuke; Matsumoto, Koki; Nagatani, Asahiro; Tanaka, Tatsuya; Arao, Yoshihiko

    2015-05-01

    We investigated the efficient use of cellulose to resolve the problem of the depletion of fossil resources. In this study, as the biomass material, the green composite based on natural rubber (NR) and the flake-shaped cellulose particles (FSCP) was produced. In order to further improvement of functional characteristics, epoxidized natural rubber (ENR) was also used instead of NR. The FSCP were produced by mechanical milling in a planetary ball mill with a grinding aid as a cellulose aggregation inhibitor. Moreover, talc and mica particles were used to compare with FSCP. NR and ENR was mixed with vulcanizing agents and then each filler was added to NR compound in an internal mixer. The vulcanizing agents are as follows: stearic acid, zinc oxide, sulfur, and vulcanization accelerator. The functionalities of the composites were evaluated by a vibration-damping experiment and a gas permeability experiment. As a result, we found that FSCP filler has effects similar to (or more than) inorganic filler in vibration-damping and O2 barrier properties. And then, vibration- damping and O2 barrier properties of the composite including FSCP was increased with use of ENR. In particular, we found that ENR-50 composite containing 50 phr FSCP has three times as high vibration-damping property as ENR-50 without FSCP.

  4. Improvement of toughness and water resistance of bioplastic based on wheat gluten using epoxidized natural rubber

    NASA Astrophysics Data System (ADS)

    Hemsri, S.; Thongpin, C.; Somkid, P.; Sae-arma, S.; Paiykaew, A.

    2015-07-01

    Novel blends based on wheat gluten (WG) and epoxidized natural rubber (ENR) were fabricated with different ENR contents of 10, 20 and 30 wt% in an internal mixer. Sulfur vulcanization was used to crosslink the ENR phase in the blends. Comparatively, blends of WG and natural rubber (WG/NR) were prepared in the same condition as the WG/ENR blends. Tensile mechanical properties and impact strength of the WG/ENR blends were investigated and compared with the WG/NR blends as well as pure WG. Moreover, water absorption of pure WG and the WG/ENR blends was also tested. As investigated by scanning electron microscopy (SEM), the results revealed more compatibility between WG and ENR compared with NR. The elongation at break, impact strength and water resistance of the WG/ENR blends were found to remarkably increase with respect to the pure WG. Thus, incorporation of ENR into WG could improve toughness and water resistance of WG. Furthermore, the effect of adding glycerol acting as a plasticizer on the mechanical properties and impact strength of the WG/ENR blends was also studied. The blends with glycerol-plasticized WG (WG-Gly/ENR) showed more homogeneous morphologies and superior results in the mechanical properties and impact strength compared with the WG/ENR blends.

  5. Radiation prevulcanized natural rubber latex: Cytotoxicity and safety evaluation on animal

    NASA Astrophysics Data System (ADS)

    Keong, C. C.; Zin, W. M. Wan; Ibrahim, P.; Ibrahim, S.

    2010-05-01

    Radiation prevulcanized natural rubber latex (RVNRL) was claimed to be more user friendly than natural rubber latex prevulcanized by sulphur curing system. The absence of Type IV allergy inducing chemicals in RVNRL make it a suitable material for manufacturing of many kinds of latex products, especially those come into direct contact with users. This paper reveals and discusses the findings of cytotoxicity test and safety evaluation on animal for RVNRL. The test was done on RVNRL films prepared by coagulant dipping method and RVNRL dipped products produced by latex dipped product manufacturers. Cytotocixity test was carried out on mammalian cell culture American Type Culture Collection CCL 81, Vero. Results indicated that no cytotoxic effect from RVNRL films and products was found on the cell culture. Two animal studies, namely dermal sensitization study and primary skin irritation study, were done on gloves made from RVNRL. Albino white guinea pigs were used as test subjects in dermal sensitization study and results showed no sensitization induced by the application of test material in the guinea pigs. Primary skin irritation study was done on New Zealand white rabbits and results showed that the product tested was not corrosive and was not a primary irritant

  6. Effect of Ultrasonic Treatment on The Tensile and Impact Properties of Thermoplastic Natural Rubber Nanocomposites Reinforced with Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Tarawneh, Mou'ad A.; Ahmad, Sahrim Hj.; Yahya, S. Y.; Rasid, Rozaidi

    2009-06-01

    This study investigates the effect of ultrasonic treatment on the mechanical properties of thermoplastic natural rubber (TPNR) nanocomposites reinforced with multi-walled nanotubes. The TPNR nanocomposites were prepared using melt blending method from polypropylene (PP), natural rubber (NR) and liquid natural rubber (LNR) as a compatibilizer, respectively, with 1% of Multi-wall nanotubes. The nanocomposite was prepared using the indirect technique (IDT) with the optimum processing parameters at 180° C with 80 rpm mixing speed and 11 minutes processing time. The results have showed that the good dispersion on nanotubes was achieved by ultrasonic treatment. The optimization of ultrasonic time indicated that the maximum tensile and impact properties occurred with 1 h ultrasonic treatment. The Young's modulus, tensile strength, elongation at break and impact strength have increased by almost 11%, 21%, 43% and 50%, respectively. The results from our study indicate that nanotubes have as excellent reinforcement filler in TPNR matrix.

  7. Effect of Ultrasonic Treatment on The Tensile and Impact Properties of Thermoplastic Natural Rubber Nanocomposites Reinforced with Carbon Nanotubes

    SciTech Connect

    Tarawneh, Mou'ad A.; Ahmad, Sahrim Hj.; Rasid, Rozaidi; Yahya, S. Y.

    2009-06-01

    This study investigates the effect of ultrasonic treatment on the mechanical properties of thermoplastic natural rubber (TPNR) nanocomposites reinforced with multi-walled nanotubes. The TPNR nanocomposites were prepared using melt blending method from polypropylene (PP), natural rubber (NR) and liquid natural rubber (LNR) as a compatibilizer, respectively, with 1% of Multi-wall nanotubes. The nanocomposite was prepared using the indirect technique (IDT) with the optimum processing parameters at 180 deg. C with 80 rpm mixing speed and 11 minutes processing time. The results have showed that the good dispersion on nanotubes was achieved by ultrasonic treatment. The optimization of ultrasonic time indicated that the maximum tensile and impact properties occurred with 1 h ultrasonic treatment. The Young's modulus, tensile strength, elongation at break and impact strength have increased by almost 11%, 21%, 43% and 50%, respectively. The results from our study indicate that nanotubes have as excellent reinforcement filler in TPNR matrix.

  8. Ericameria Nauseosa (rubber rabbitbrush): a complementary rubber feedstock to augment the guayule rubber production stream

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ericameria nauseosa (rubber rabbitbrush) is a highly prolific desert shrub that produces high quality natural rubber. Over the past several years we have investigated rabbitbrush’s potential as a commercial rubber feedstock. Like guayule, rabbitbrush produces natural rubber within its bark tissues a...

  9. A novel use of bio-based natural fibers, polymers, and rubbers for composite materials

    NASA Astrophysics Data System (ADS)

    Modi, Sunny Jitendra

    The composites, materials, and packaging industries are searching for alternative materials to attain environmental sustainability. Bio-plastics are highly desired and current microbially-derived bio-plastics, such as PHA (poly-(hydroxy alkanoate)), PHB (poly-(hydroxybutyrate)), and PHBV (poly-(beta-hydroxy butyrate-co-valerate)) could be engineered to have similar properties to conventional thermoplastics. Poly-(hydroxybutyrate) (PHB) is a bio-degradable aliphatic polyester that is produced by a wide range of microorganisms. Basic PHB has relatively high glass transition and melting temperatures. To improve flexibility for potential packaging applications, PHB is synthesized with various co-polymers such as Poly-(3-hydroxyvalerate) (HV) to decrease the glass and melting temperatures and, since there is improved melt stability at lower processing temperatures, broaden the processing window. However, previous work has shown that this polymer is too brittle, temperature-sensitive, and hydrophilic to meet packaging material physical requirements. Therefore, the proposed work focuses on addressing the needs for bio-derived and bio-degradable materials by creating a range of composite materials using natural fibers as reinforcement agents in bio-polymers and bio- plastic-rubber matrices. The new materials should possess properties lacking in PHBV and broaden the processing capabilities, elasticity, and improve the mechanical properties. The first approach was to create novel composites using poly-(beta-hydroxy butyrate-co-valerate) (PHBV) combined with fibers from invasive plants such as common reed (Phragmites australis), reed canary grass (Phalaris arundinacea), and water celery ( Vallisneria americana). The composites were manufactured using traditional processing techniques of extrusion compounding followed by injection molding of ASTM type I parts. The effects of each bio-fiber at 2, 5, and 10% loading on the mechanical, morphological, rheological, and thermal

  10. PMMA-N,N,N-trimethyl chitosan nanoparticles for fabrication of antibacterial natural rubber latex gloves.

    PubMed

    Arpornwichanop, Thanida; Polpanich, Duangporn; Thiramanas, Raweewan; Suteewong, Teeraporn; Tangboriboonrat, Pramuan

    2014-08-30

    This paper presents one-pot synthesis of N,N,N-trimethyl chitosan (TMC) stabilized poly(methyl methacrylate) (PMMA) latex particles via the miniemulsion polymerization technique. From (1)H NMR, synthesized TMC contains 52% degree of quaternization. Compared to native biopolymer chitosan, TMC possesses permanently positive charges as well as provides greater antibacterial activity. Combining properties of PMMA and TMC, PMMA-TMC latex nanoparticles (hydrodynamic size ≈282 nm) could be used in place of inorganic lubricating powder in fabrication of latex gloves at pH ≥ 7. After immersing sulphur prevulcanized natural rubber (SPNR) film into 3 wt% of PMMA-TMC latex at pH 7, significant amount of nanoparticles uniformly deposited onto SPNR film was observed under SEM. A number of nanoparticles present on film surface would increase surface roughness of the rubber film and potentially inhibit the bacterial (Escherichia coli and Staphylococcus aureus) growth, which would be useful for fabrication of special gloves with antibacterial property. PMID:24815393

  11. Biodegradation potential of a modified natural product

    SciTech Connect

    Sajjad, W.

    1996-12-31

    Biodegradation potential of a modified natural product for treating petroleum contaminated soils was investigated along with some commercially available microbial cultures in three different scales from a laboratory to pilot to case studies. The modified natural product is lignocellulosic in nature and proprietary product of a company in Iowa. The production process of this product involves mechanical size reduction, blending/coating, and aerobic digestion of hay, corn cob residue, straw or crop residue in presence of poultry manure. The degradation kinetics of the petroleum products in the contaminated soils were measured both directly and indirectly. Residual petroleum products in different soils (treated and untreated) at various time periods were quantified by gas chromatographic (GC) analysis on extracted samples. The indirect assessment of the kinetics of biological activity involved the measurement of CO{sub 2} evolved from flasks (250 ml capacity) containing contaminated soil (about 50 ml) with various treatments. The results indicated that the biodegradation kinetics of petroleum products in the contaminated soils were significantly improved by treatment with this modified natural product. In most cases tested, this product performed significantly better than the available commercial bacterial cultures for biological removal of petroleum products from contaminated soils. This study also demonstrated the significance of temperature and moisture content in biodegradation kinetics.

  12. Properties of natural rubber/attapulgite composites prepared by latex compounding method: Effect of filler loading

    NASA Astrophysics Data System (ADS)

    Muttalib, Siti Nadzirah Abdul; Othman, Nadras; Ismail, Hanafi

    2015-07-01

    This paper reports on the effect of filler loading on properties of natural rubber (NR)/attapulgite (ATP) composites. The NR/ATP composites were prepared by latex compounding method. It is called as masterbatch. The masterbatch was subsequently added to the NR through melt mixing process. The vulcanized NR/ATP composites were subjected to mechanical, swelling and morphological tests. All the results were compared with NR/ATP composites prepared by conventional system. The composites from masterbatch method showed better results compared to composites prepared by conventional method. They have higher tensile properties, elongation at break and tear strength. The images captured through scanning electron microscopy test revealed the improvement of tensile strength in masterbatch NR/ATP composites. It can be seen clearly that masterbatch NR/ATP have better filler dispersion compared to conventional method NR/ATP composites.

  13. Data for effects of lanthanum complex on the thermo-oxidative aging of natural rubber

    PubMed Central

    Zheng, Wei; Liu, Li; Zhao, Xiuying; He, Jingwei; Wang, Ao; Chan, Tung W.; Wu, Sizhu

    2015-01-01

    Novel mixed antioxidants composed of antioxidant IPPD and lanthanum (La) complex were added as a filler to form natural rubber (NR) composites. By mechanical testing, Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) and thermogravimetric analysis (TGA), a string of data, including the mechanical properties, the variation of internal groups and the thermal and thermo-oxidative decompositions of NR, was presented in this data article. The data accompanying its research article [1] studied the thermo-oxidative aging properties of NR in detail. The density function theoretical (DFT) calculations were also used as an assistant to study the thermo-oxidative aging mechanism of NR. The data revealed that this new rare-earth antioxidant could indeed enhance the thermo-oxidative aging resistance of NR, which is associated with its different function mechanism from that of the pure antioxidant IPPD. PMID:26693513

  14. Tensile and Impact Properties of Thermoplastic Natural Rubber (TPNR) Filled with Carbon Nanotubes (MWNTs)

    NASA Astrophysics Data System (ADS)

    Tarawneh, Mou'ad. A.; Ahmad, Sahrim Hj.; Yahya, S. Y.; Rasid, Rozaidi; Hock, Yew Chin; Halim, Hazwani Binti

    2010-07-01

    This paper discusses the effect of multi-walled carbon nanotubes (MWNT) on the tensile and impact properties of thermoplastic natural rubber (TPNR) nanocomposite. The nanocomposite was prepared using melt blending method. MWNT were added to improve the mechanical properties of MWNTs/TPNR composites at different compositions which is 1, 3, 5, and 7 wt.%. The result of tensile test showed that tensile strength and Young's modulus increase in the presence of nanotubes and maximum value are obtained with 3 wt.% of MWNTs. On other hand, higher MWNTs concentration has caused the formation of aggregates. The elongation at break considerably decreased with increasing the percentage of MWNTs. The maximum impact strength is recorded with 5 wt.% of MWNTs. SEM micrograph has confirmed the homogenous dispersion of MWNTs in the TPNR matrix and promoted strong interfacial adhesion between MWNTs and the matrix which is improved mechanical significantly.

  15. Mechanical characterization and morphology of polylactic acid /liquid natural rubber filled with multi walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ali, Adilah Mat; Ahmad, Sahrim Hj.

    2013-11-01

    In this paper the polymer nanocomposite of multi-walled carbon nanotubes (MWCNTs) nanoparticles was incorporated with polylactic acid (PLA) and liquid natural rubber (LNR) as compatibilizer were prepared via melt blending method. The effect of MWCNTs loading on the tensile and impact properties of nanocomposites was investigated. The result has shown that the sample with 3.5 wt % of MWCNTs exhibited higher tensile strength, Young's modulus and impact strength. The elongation at break decreased with increasing percentage of MWCNTs. The SEM micrographs confirmed the effect of good dispersion of MWCNTs and their interfacial bonding in PLA/LNR composites. The improved dispersion of MWCNTs can be obtained due to altered interparticle interactions, MWCNTs-MWCNTs and MWCNTs-matrix networks are well combined to generate the synergistic effect of the system as shown by SEM micrographs which is improved the properties significantly.

  16. Properties of natural rubber/attapulgite composites prepared by latex compounding method: Effect of filler loading

    SciTech Connect

    Muttalib, Siti Nadzirah Abdul Othman, Nadras Ismail, Hanafi

    2015-07-22

    This paper reports on the effect of filler loading on properties of natural rubber (NR)/attapulgite (ATP) composites. The NR/ATP composites were prepared by latex compounding method. It is called as masterbatch. The masterbatch was subsequently added to the NR through melt mixing process. The vulcanized NR/ATP composites were subjected to mechanical, swelling and morphological tests. All the results were compared with NR/ATP composites prepared by conventional system. The composites from masterbatch method showed better results compared to composites prepared by conventional method. They have higher tensile properties, elongation at break and tear strength. The images captured through scanning electron microscopy test revealed the improvement of tensile strength in masterbatch NR/ATP composites. It can be seen clearly that masterbatch NR/ATP have better filler dispersion compared to conventional method NR/ATP composites.

  17. Polypropylene/natural rubber thermoplastic vulcanizates by eco-friendly and sustainable electron induced reactive processing

    NASA Astrophysics Data System (ADS)

    Mondal, Manas; Gohs, Uwe; Wagenknecht, Udo; Heinrich, Gert

    2013-07-01

    TPVs are a special class of thermoplastic and elastomer blend where cross-linking of elastomeric phase takes place during melt mixing process known as dynamic vulcanization (DV). A 50/50 blend of natural rubber (NR) and polypropylene (PP) were dynamically vulcanized using Electron Induced Reactive Processing (EIReP) as a function of absorbed dose (150, 250, and 350 kGy) at fixed electron energy (1.5 MeV) and dose per rotation. Different methods like tensile test, DSC, melt rheology, and SEM have been employed to understand the structure-property relationship of the prepared samples. The results suggest that EIReP is a novel technique to offer handful of additional features without compromising the end user property.

  18. Effect of bentonite modification on hardness and mechanical properties of natural rubber nanocomposites

    NASA Astrophysics Data System (ADS)

    Santiago, Denise Ester O.; Pajarito, Bryan B.; Mangaccat, Winna Faye F.; Tigue, Maelyn Rose M.; Tipton, Monica T.

    2016-05-01

    The effect of sodium activation, ion-exchange with tertiary amine salt, surface treatment with non-ionic surfactant, and wet grinding of bentonite on hardness and mechanical properties of natural rubber nanocomposites (NRN) was studied using full factorial design of experiment. Results of X-ray diffraction (XRD) show increase in basal spacing d of bentonite due to modification, while attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) confirm the organic modification of bentonite. Analysis of variance (ANOVA) shows that the main effect of surface treatment increases the hardness and decreases the tensile modulus of the NRN. The surface treatment and wet grinding of bentonite decrease the tensile stresses at 100, 200 and 300% strain of NRN. Sodium activation and ion-exchange negatively affect the compressive properties, while surface treatment significantly improves the compressive properties of NRN.

  19. Photovoltaic Cells involving Nonconjugated Conductive Polymer, Iodine-doped cis-Polyisoprene (Natural Rubber)

    NASA Astrophysics Data System (ADS)

    Jaju, S.; Thakur, M.

    2014-03-01

    Photovoltaic cells have been fabricated using titanium dioxide/doped cis-polyisoprene/carbon on ITO glass-substrates. Photocurrents and photo-voltages for different intensities of light (from a white light bulb, emission at 300-700 nm) have been measured. Use of the iodine-doped nonconjugated conductive polymer film (absorption ~ 250 to 700 nm) has led to significant enhancement of photocurrent compared to previous reports which included undoped polymer in a different cell-structure. A maximum photocurrent of about 0.20 mA was observed for a light intensity of ~ 5 mW/cm2. The maximum photo-voltage as observed was about 0.70 V for the same light intensity. Natural rubber being inexpensive these cells may provide cheaper alternatives to other reported cell structures.

  20. VISCOELASTIC PROPERTIES OF NATURAL RUBBER COMPOSITES REINFORCED BY DEFATTED SOY FLOUR AND CARBON BLACK CO-FILLER

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Filler mixtures of defatted soy flour (DSF) and carbon black (CB) were used to reinforce natural rubber (NR) composites and their viscoelastic properties were investigated. DSF is an abundant and renewable commodity and has a lower material cost than CB. Aqueous dispersions of DSF and CB were firs...

  1. [The consideration and several suggestions on the national standard GB 7544 natural latex rubber condoms--requirements and test methods].

    PubMed

    Xiao, Yimei

    2010-11-01

    It was found that several problems exist in the implementation of GB 7544-2004 in the aspects of requirements of natural latex materials and safety of rubber condom products, microorganisms to be controlled and the packaging and label. As a result, the suggestions were put forward. PMID:21360987

  2. Particle size and particle-particle interactions on tensile properties and reinforcement of corn flour particles in natural rubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Renewable corn flour has a significant reinforcement effect in natural rubber. The corn flour was hydrolyzed and microfluidized to reduce its particle size. Greater than 90% of the hydrolyzed corn flour had an average size of ~300 nm, a reduction of 33 times compared to unhydrolyzed corn flour. Comp...

  3. Effect of added silicon carbide nanowires and carbon nanotubes on mechanical properties of 0-3 natural rubber composites

    NASA Astrophysics Data System (ADS)

    Janyakunmongkol, Khantichai; Nhuapeng, Wim; Thamjaree, Wandee

    2016-01-01

    In this work, the mechanical properties of 0-3 nanocomposite materials containing silicon carbide nanowires (SiCNWs), carbon nanotubes (CNTs), and natural rubber were studied. The SiCNWs and CNTs were used as reinforcement fiber whereas natural rubber was used as the matrix phase. The chemical vapor depositions (CVD) was used for synthesizing the nanowire and nanotube phases. The volume fraction of reinforcement was varied from 0 to 10%. The nanophases were mixed in the natural rubber matrix and molded by the hand lay-up technique. The mechanical properties of the samples were examined and compared with those of neat natural rubber. From the results, it was found that the hardness and density of the samples increased with the quantities of nanophases. The nanocomposites with a volume fraction of 10% exhibited maximum hardness (50.5 SHORE A). The maximum tensile strength and extent of elongation at break of the samples were obtained from the 4% volume fraction sample, which were 16.13 MPa and 1,540%, respectively.

  4. A lettuce (Lactuca sativa) homolog of human Nogo-B receptor interacts with cis-prenyltransferase and is necessary for natural rubber biosynthesis.

    PubMed

    Qu, Yang; Chakrabarty, Romit; Tran, Hue T; Kwon, Eun-Joo G; Kwon, Moonhyuk; Nguyen, Trinh-Don; Ro, Dae-Kyun

    2015-01-23

    Natural rubber (cis-1,4-polyisoprene) is an indispensable biopolymer used to manufacture diverse consumer products. Although a major source of natural rubber is the rubber tree (Hevea brasiliensis), lettuce (Lactuca sativa) is also known to synthesize natural rubber. Here, we report that an unusual cis-prenyltransferase-like 2 (CPTL2) that lacks the conserved motifs of conventional cis-prenyltransferase is required for natural rubber biosynthesis in lettuce. CPTL2, identified from the lettuce rubber particle proteome, displays homology to a human NogoB receptor and is predominantly expressed in latex. Multiple transgenic lettuces expressing CPTL2-RNAi constructs showed that a decrease of CPTL2 transcripts (3-15% CPTL2 expression relative to controls) coincided with the reduction of natural rubber as low as 5%. We also identified a conventional cis-prenyltransferase 3 (CPT3), exclusively expressed in latex. In subcellular localization studies using fluorescent proteins, cytosolic CPT3 was relocalized to endoplasmic reticulum by co-occurrence of CPTL2 in tobacco and yeast at the log phase. Furthermore, yeast two-hybrid data showed that CPTL2 and CPT3 interact. Yeast microsomes containing CPTL2/CPT3 showed enhanced synthesis of short cis-polyisoprenes, but natural rubber could not be synthesized in vitro. Intriguingly, a homologous pair CPTL1/CPT1, which displays ubiquitous expressions in lettuce, showed a potent dolichol biosynthetic activity in vitro. Taken together, our data suggest that CPTL2 is a scaffolding protein that tethers CPT3 on endoplasmic reticulum and is necessary for natural rubber biosynthesis in planta, but yeast-expressed CPTL2 and CPT3 alone could not synthesize high molecular weight natural rubber in vitro. PMID:25477521

  5. A Lettuce (Lactuca sativa) Homolog of Human Nogo-B Receptor Interacts with cis-Prenyltransferase and Is Necessary for Natural Rubber Biosynthesis*

    PubMed Central

    Qu, Yang; Chakrabarty, Romit; Tran, Hue T.; Kwon, Eun-Joo G.; Kwon, Moonhyuk; Nguyen, Trinh-Don; Ro, Dae-Kyun

    2015-01-01

    Natural rubber (cis-1,4-polyisoprene) is an indispensable biopolymer used to manufacture diverse consumer products. Although a major source of natural rubber is the rubber tree (Hevea brasiliensis), lettuce (Lactuca sativa) is also known to synthesize natural rubber. Here, we report that an unusual cis-prenyltransferase-like 2 (CPTL2) that lacks the conserved motifs of conventional cis-prenyltransferase is required for natural rubber biosynthesis in lettuce. CPTL2, identified from the lettuce rubber particle proteome, displays homology to a human NogoB receptor and is predominantly expressed in latex. Multiple transgenic lettuces expressing CPTL2-RNAi constructs showed that a decrease of CPTL2 transcripts (3–15% CPTL2 expression relative to controls) coincided with the reduction of natural rubber as low as 5%. We also identified a conventional cis-prenyltransferase 3 (CPT3), exclusively expressed in latex. In subcellular localization studies using fluorescent proteins, cytosolic CPT3 was relocalized to endoplasmic reticulum by co-occurrence of CPTL2 in tobacco and yeast at the log phase. Furthermore, yeast two-hybrid data showed that CPTL2 and CPT3 interact. Yeast microsomes containing CPTL2/CPT3 showed enhanced synthesis of short cis-polyisoprenes, but natural rubber could not be synthesized in vitro. Intriguingly, a homologous pair CPTL1/CPT1, which displays ubiquitous expressions in lettuce, showed a potent dolichol biosynthetic activity in vitro. Taken together, our data suggest that CPTL2 is a scaffolding protein that tethers CPT3 on endoplasmic reticulum and is necessary for natural rubber biosynthesis in planta, but yeast-expressed CPTL2 and CPT3 alone could not synthesize high molecular weight natural rubber in vitro. PMID:25477521

  6. Permeation study of indomethacin from polycarbazole/natural rubber blend film for electric field controlled transdermal delivery.

    PubMed

    Thorngkham, Pornwalai; Paradee, Nophawan; Niamlang, Sumonman; Sirivat, Anuvat

    2015-05-01

    Transdermal drug delivery is an alternative route to transport the drug into the blood system. This method has been continuously developed to overcome limitations and is now suitable for a wide variety of drug molecules. In this work, the influences of electric field and conductive polymer were investigated for developing a unique drug delivery system from double-centrifuged natural rubber (DCNR) matrix. Indomethacin (IN) was loaded into polycarbazole (PCz) as a conductive polymer drug host to promote the efficient transportation of the drug. The IN-loaded PCz was blended with DCNR to form a transdermal patch. The permeation of IN through the PCz/NR film and pig skin was carrried out by a modified Franz diffusion cell. The IN diffused from DCNR film by the diffusion controlled combined with erosion mechanism depending on the pore formation period. The drug permeation increased with decreasing cross-link ratio because of more accessible pathways for the drug permeation. Moreover, an electric field and the inclusion of PCz as the drug carrier dramatically improved the diffusion of the drug from the membrane by through the electrorepulsive force and electro-reduced PCz expansion. Thus, the PCz/DCNR films are shown here as a potential transdermal patch under applied electric field. PMID:25754446

  7. Morphology and phase composition of an amine cured rubber modified epoxy

    SciTech Connect

    Sayre, J.A.; Assink, R.A.; Lagasse, R.R.

    1980-01-01

    The sharpness of the interface between the matrix and the dispersed phase, the volume fraction of the dispersed phase, the distribution of particle sizes, and the concentration of epoxy in the dispersed phase were determined. Scanning transmission electron microscopy coupled with energy dispersive x-ray analysis revealed that the interface width is less than 500 A. Variation of the fraction of mobile hydrogens with temperature determined by nuclear magnetic resonance indicated that a small fraction of segments participated in mixing at the interface. Differential scanning calorimetry and nuclear magnetic resonance indicated that all the rubber precipitates as a discrete phase. The distribution of particles greater than 0.1 ..mu..m in diameter was measured, and the average diameter of these particles was found to be 0.8 ..mu..m. The particles larger than 0.1 ..mu..m accounted for approximately 50% of the total volume of dispersed phase. The epoxy concentration in the dispersed phase was determined using /sup 13/C nuclear magnetic resonance spectroscopy. This concentration was found to be less than that predicted if all the epoxy monomer units attached to the rubber molecules were present in the dispersed phase.

  8. A comparison of the abilities of natural rubber (NR) and synthetic polyisoprene cis-1,4 rubber (IR) to crystallize under strain at high strain rates.

    PubMed

    Candau, Nicolas; Chazeau, Laurent; Chenal, Jean-Marc; Gauthier, Catherine; Munch, Etienne

    2016-02-01

    Strain induced crystallization (SIC) of a natural rubber (NR) and a synthetic rubber (IR) with a high amount of cis-1,4 units (98.6%) is studied, thanks to in situ wide angle X-ray (WAXS) experiments at room temperature performed in a large range of strain rates. During stretching at a low strain rate (4.2 × 10(-3) s(-1)), SIC in IR occurs at a larger stretching ratio than in NR. As a result, the crystallinity index at a given stretching ratio is lower in IR than in NR, in spite of the similar crosslink densities of the chains involved in the crystallization in both materials. This lower ability for crystallization in IR is attributed to the presence of branching along its backbone and its lower stereoregularity. Conversely, dynamic experiments performed at high strain rates (10(1)/10(2) s(-1)) show for both materials a similar ability to crystallize. This unexpected result is confirmed by monotonic tensile tests performed in a large range of strain rates. The reason is thermodynamic: the chain extension plays a predominant role compared to the role of the microstructure defects when the strain rate is high, i.e. when the kinetics of the crystallite nucleation forces the crystallization to occur at a large stretching ratio. A thermodynamic model enables qualitative reproduction of the experimental results. PMID:26750589

  9. Electrical and optical properties of nitrile rubber modified by ion implantation

    SciTech Connect

    S, Najidha; Predeep, P.

    2014-10-15

    Implantation of N{sup +} ion beams are performed on to a non-conjugated elastomer, acrylonirtle butadiene rubber (NBR) with energy 60 keV in the fluence range of 10{sup 14} to 10{sup 16} ions/cm{sup 2}. A decrease in the resistivity of the sample by about eight orders of magnitude is observed in the implanted samples along with color changes. The ion exposed specimens were characterized by means of UV/Vis spectroscopy which shows a shift in the absorption edge value for the as deposited polymer towards higher wavelengths. The band gap is evaluated from the absorption spectra and is found to decrease with increasing fluence. This study can possibly throw light on ion induced changes in the polymer surface.

  10. Electrical and optical properties of nitrile rubber modified by ion implantation

    NASA Astrophysics Data System (ADS)

    S, Najidha; Predeep, P.

    2014-10-01

    Implantation of N+ ion beams are performed on to a non-conjugated elastomer, acrylonirtle butadiene rubber (NBR) with energy 60 keV in the fluence range of 1014 to 1016 ions/cm2. A decrease in the resistivity of the sample by about eight orders of magnitude is observed in the implanted samples along with color changes. The ion exposed specimens were characterized by means of UV/Vis spectroscopy which shows a shift in the absorption edge value for the as deposited polymer towards higher wavelengths. The band gap is evaluated from the absorption spectra and is found to decrease with increasing fluence. This study can possibly throw light on ion induced changes in the polymer surface.

  11. A novel use of bio-based natural fibers, polymers, and rubbers for composite materials

    NASA Astrophysics Data System (ADS)

    Modi, Sunny Jitendra

    The composites, materials, and packaging industries are searching for alternative materials to attain environmental sustainability. Bio-plastics are highly desired and current microbially-derived bio-plastics, such as PHA (poly-(hydroxy alkanoate)), PHB (poly-(hydroxybutyrate)), and PHBV (poly-(beta-hydroxy butyrate-co-valerate)) could be engineered to have similar properties to conventional thermoplastics. Poly-(hydroxybutyrate) (PHB) is a bio-degradable aliphatic polyester that is produced by a wide range of microorganisms. Basic PHB has relatively high glass transition and melting temperatures. To improve flexibility for potential packaging applications, PHB is synthesized with various co-polymers such as Poly-(3-hydroxyvalerate) (HV) to decrease the glass and melting temperatures and, since there is improved melt stability at lower processing temperatures, broaden the processing window. However, previous work has shown that this polymer is too brittle, temperature-sensitive, and hydrophilic to meet packaging material physical requirements. Therefore, the proposed work focuses on addressing the needs for bio-derived and bio-degradable materials by creating a range of composite materials using natural fibers as reinforcement agents in bio-polymers and bio- plastic-rubber matrices. The new materials should possess properties lacking in PHBV and broaden the processing capabilities, elasticity, and improve the mechanical properties. The first approach was to create novel composites using poly-(beta-hydroxy butyrate-co-valerate) (PHBV) combined with fibers from invasive plants such as common reed (Phragmites australis), reed canary grass (Phalaris arundinacea), and water celery ( Vallisneria americana). The composites were manufactured using traditional processing techniques of extrusion compounding followed by injection molding of ASTM type I parts. The effects of each bio-fiber at 2, 5, and 10% loading on the mechanical, morphological, rheological, and thermal

  12. Inducing uniform single-crystal like orientation in natural rubber with constrained uniaxial stretch.

    PubMed

    Zhou, Weiming; Meng, Lingpu; Lu, Jie; Wang, Zhen; Zhang, Wenhua; Huang, Ningdong; Chen, Liang; Li, Liangbin

    2015-07-01

    The effect of flow on crystallization is commonly attributed to entropic reduction, which is caused by stretch and orientation of polymer chains but overlooks the role of flow on final-state free energy. With the aid of in situ synchrotron radiation wide-angle X-ray diffraction (WAXD) and a homemade constrained uniaxial tensile testing machine, polycrystals possessing single-crystal-like orientation rather than uniaxial orientation are found during the constrained stretch of natural rubber, whereas the c-axis and a-axis align in the stretch direction (SD) and constrained direction (CD), respectively. Molecular dynamics simulation shows that aligning the a-axis of crystal nuclei in CD leads to the lowest free energy increase and favors crystal nucleation. This indicates that the nomenclature of strain-induced crystallization may not fully account for the nature of flow-induced crystallization (FIC) as strain mainly emphasizes the entropic reduction of initial melt, whereas stress rather than strain plays the dominant role in crystal deformation. The current work not only contributes to a comprehensive understanding of the mechanism of flow-induced crystallization but also demonstrates the potential application of constrained uniaxial tensile stretch for the creation of functional materials containing polycrystals that possess single-crystal-like orientation. PMID:26021287

  13. Amphiphilic semi-interpenetrating polymer networks using pulverized rubber

    NASA Astrophysics Data System (ADS)

    Shahidi, Nima

    Scrap rubber materials provide a significant challenge to either reuse or safe disposal. Every year, millions of tires are discarded to landfills in the United States, consuming a staggering amount of land space, creating a high risk for large fires, breeding mosquitoes that spread diseases, and wasting the planet's natural resources. This situation cannot be sustained. The challenge of reusing scrap rubber materials is mainly due to the crosslinked structure of vulcanized rubber that prevent them from melting and further processing for reuse. The most feasible recycling approach is believed to be a process in which the vulcanized rubber is first pulverized into a fine powder and then incorporated into new products. The production of fine rubber particles is generally accomplished through the use of a cryogenic process that is costly. Therefore, development of a cost effective technology that utilizes a large quantity of the scrap rubber materials to produce high value added materials is an essential element in maintaining a sustainable solution to rubber recycling. In this research, a cost effective pulverization process, solid state shear extrusion (SSSE), was modified and used for continuous pulverization of the rubber into fine particles. In the modified SSSE process, pulverization takes place at high compressive shear forces and a controlled temperature. Furthermore, an innovative particle modification process was developed to enhance the chemical structure and surface properties of the rubber particles for manufacturing of high value added products. Modification of rubber particles was accomplished through the polymerization of a hydrophilic monomer mixture within the intermolecular structure of the hydrophobic rubber particles. The resulting composite particles are considered as amphiphilic particulate phase semi-interpenetrating polymer networks (PPSIPNs). The modified rubber particles are water dispersible and suitable for use in a variety of aqueous media

  14. In situ synchrotron wide-angle X-ray diffraction investigation of fatigue cracks in natural rubber.

    PubMed

    Rublon, Pierre; Huneau, Bertrand; Saintier, Nicolas; Beurrot, Stéphanie; Leygue, Adrien; Verron, Erwan; Mocuta, Cristian; Thiaudière, Dominique; Berghezan, Daniel

    2013-01-01

    Natural rubber exhibits remarkable mechanical fatigue properties usually attributed to strain-induced crystallization. To investigate this phenomenon, an original experimental set-up that couples synchrotron radiation with a homemade fatigue machine has been developed. Diffraction-pattern recording is synchronized with cyclic loading in order to obtain spatial distributions of crystallinity in the sample at prescribed times of the mechanical cycles. Then, real-time measurement of crystallinity is permitted during uninterrupted fatigue experiments. First results demonstrate the relevance of the method: the set-up is successfully used to measure the crystallinity distribution around a fatigue crack tip in a carbon black filled natural rubber for different loading conditions. PMID:23254662

  15. Preparation and mechanical properties of the magnetorheological elastomer based on natural rubber/rosin glycerin hybrid matrix

    NASA Astrophysics Data System (ADS)

    Ge, Lin; Gong, Xinglong; Fan, Yanceng; Xuan, Shouhu

    2013-11-01

    To improve the mechanical properties of the natural rubber based magnetorheological elastomers (MREs), rosin glycerin ester was added into the carrier matrix to enhance wettability and dispersibility of CI particles. Dynamic performance, including shear modulus, loss factor and viscosity of non-vulcanized matrix was measured by rheometer. In comparison to the natural rubber based MREs, the MR effect of these hybrid matrix MREs were higher and they can reach to 112% when the mass fraction of CI particles is only 60%. The contact angle was tested by drop shape analysis system (DSA) and it was found that the compatibility between the iron particles and matrix was improved. In combination of the microstructure and mechanical property analysis, a possible mechanism was proposed. Finally, the loss factor and tensile strength were studied.

  16. A Carboxyl-Terminated Polybutadiene Liquid Rubber Modified Epoxy Resin with Enhanced Toughness and Excellent Electrical Properties

    NASA Astrophysics Data System (ADS)

    Dong, Lina; Zhou, Wenying; Sui, Xuezhen; Wang, Zijun; Cai, Huiwu; Wu, Peng; Zuo, Jing; Liu, Xiangrong

    2016-07-01

    The modification of epoxy (EP) resin with carboxyl-terminated polybutadiene (CTPB) liquid rubber was carried out in this work. The chemical reaction between the oxirane ring of EP and the carboxyl group of CTPB and kinetic parameters were investigated by Fourier transform infrared and differential scanning calorimetry. The resulting pre-polymers were cured with methyl hexahydrophthalic anhydride. Scanning electron microscopic observations indicate that the micro-sized CTPB particles dispersed uniformly in the EP matrix formed a two-phase morphology, mainly contributing to the improved toughness of the modified network. The best overall mechanical performance was achieved with 20 phr CTPB; above it, a fall in the strength and modulus was observed. The storage modulus and loss declined with the CTPB concentration due to its lower modulus and plasticizing effect from dynamic mechanical analysis measurements. Moreover, due to the weak polarity and excellent electrical insulation of CTPB, the CTPB-modified EP presented higher electrical resistivities and breakdown strength, and low dielectric permittivity and loss compared with neat EP.

  17. A Carboxyl-Terminated Polybutadiene Liquid Rubber Modified Epoxy Resin with Enhanced Toughness and Excellent Electrical Properties

    NASA Astrophysics Data System (ADS)

    Dong, Lina; Zhou, Wenying; Sui, Xuezhen; Wang, Zijun; Cai, Huiwu; Wu, Peng; Zuo, Jing; Liu, Xiangrong

    2016-04-01

    The modification of epoxy (EP) resin with carboxyl-terminated polybutadiene (CTPB) liquid rubber was carried out in this work. The chemical reaction between the oxirane ring of EP and the carboxyl group of CTPB and kinetic parameters were investigated by Fourier transform infrared and differential scanning calorimetry. The resulting pre-polymers were cured with methyl hexahydrophthalic anhydride. Scanning electron microscopic observations indicate that the micro-sized CTPB particles dispersed uniformly in the EP matrix formed a two-phase morphology, mainly contributing to the improved toughness of the modified network. The best overall mechanical performance was achieved with 20 phr CTPB; above it, a fall in the strength and modulus was observed. The storage modulus and loss declined with the CTPB concentration due to its lower modulus and plasticizing effect from dynamic mechanical analysis measurements. Moreover, due to the weak polarity and excellent electrical insulation of CTPB, the CTPB-modified EP presented higher electrical resistivities and breakdown strength, and low dielectric permittivity and loss compared with neat EP.

  18. Strain-induced crystallization and mechanical properties of functionalized graphene sheet-filled natural rubber

    SciTech Connect

    Ozbas, Bulent; Toki, Shigeyuki; Hsiao, Benjamin S.; Chu, Benjamin; Register, Richard A.; Aksay, Ilhan A.; Prud'homme, Robert K.; Adamson, Douglas H.

    2012-03-11

    The effects of functionalized graphene sheets (FGSs) on the mechanical properties and strain-induced crystallization of natural rubber (NR) are investigated. FGSs are predominantly single sheets of graphene with a lateral size of several hundreds of nanometers and a thickness of 1.5 nm. The effect of FGS and that of carbon black (CB) on the strain-induced crystallization of NR is compared by coupled tensile tests and X-ray diffraction experiments. Synchrotron X-ray scattering enables simultaneous measurements of stress and crystallization of NR in real time during sample stretching. The onset of crystallization occurs at significantly lower strains for FGS-filled NR samples compared with CB-filled NR, even at low loadings. Neat-NR exhibits strain-induced crystallization around a strain of 2.25, while incorporation of 1 and 4 wt % FGS shifts the crystallization to strains of 1.25 and 0.75, respectively. In contrast, loadings of 16 wt % CB do not significantly shift the critical strain for crystallization. Two-dimensional (2D) wide angle X-ray scattering patterns show minor polymer chain alignment during stretching, in accord with previous results for NR. Small angle X-ray scattering shows that FGS is aligned in the stretching direction, whereas CB does not show alignment or anisotropy. The mechanical properties of filled NR samples are investigated using cyclic tensile and dynamic mechanical measurements above and below the glass transition of NR.

  19. Blunt Trauma Performance of Fabric Systems Utilizing Natural Rubber Coated High Strength Fabrics

    SciTech Connect

    Ahmad, M. R.; Ahmad, W. Y. W.; Samsuri, A.; Salleh, J.; Abidin, M. H.

    2010-03-11

    The blunt trauma performance of fabric systems against 9 mm bullets is reported. Three shots were fired at each fabric system with impact velocity of 367+-9 m/s and the depth of indentation on the modeling clay backing was measured. The results showed that 18-layer and 21-layer all-neat fabric systems failed the blunt trauma test. However, fabric systems with natural rubber (NR) latex coated fabric layers gave lower blunt trauma of between 25-32 mm indentation depths. Deformations on the neat fabrics upon impact were identified as broken yarns, yarn stretching and yarn pull-out. Deflections of the neat fabrics were more localised. For the NR latex coated fabric layers, no significant deformation can be observed except for peeled-off regions of the NR latex film at the back surface of the last layer. From the study, it can be said that the NR latex coated fabric layers were effective in reducing the blunt trauma of fabric systems.

  20. Investigation of miscibility of p(3hydroxybutyrate-co-3hydroxyhexanoate) and epoxidized natural rubber blends

    SciTech Connect

    Akram, Faridah; Chan, Chin Han; Natarajan, Valliyappan David

    2015-08-28

    Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate [P(3HB-co-3HHx)] produced by C. necator PHB{sup −}4 harboring phaC{sub cs} from crude palm kernel oil with 21 mol% of 3-hydroxyhexanoate and epoxidized natural rubber with 25 mol% of epoxy content (ENR-25) were used to study the miscibility of the blends by attenuated total reflection-Fourier transform infrared (ATR-FTIR) and differential scanning calorimetry (DSC). The polymers used were purified and the blends were prepared by solution casting method. Nuclear magnetic resonance (NMR) spectra confirm the purity and molecular structures of P(3HB-co-3HHx) and ENR-25. FTIR spectra for different compositions of P(3HB-co-3HHx) and ENR-25 blends show absorbance change of the absorbance bands but with no significant shifting of the absorbance bands as the P(3HB-co-3HHx) content decreases, which shows that there is no intermolecular interaction between the parent polymer blends. On top of that, there are two T{sub g}s present for the blends and both remain constant for different compositions which corresponds to the T{sub g}s of the parent polymers. This indicates that the blends are immiscible.

  1. Observing Nucleation Transition in Stretched Natural Rubber through Self-Seeding.

    PubMed

    Liu, Han; Huang, Guangsu; Zeng, Jian; Xu, Lili; Fu, Xuan; Wu, Siduo; Zheng, Jing; Wu, Jinrong

    2015-09-01

    Potential competition between fringed-micelle nucleation (N1) and folded-chain nucleation (N2) widely exists in strain-induced crystallization (SIC). However, during uniaxial deformation, no in situ observational evidence of nucleation transition from N2 to N1 in SIC of natural rubber (NR) has been reported yet. In this work, self-seeding provides an effective way for this observation. By the introduction of residual TIC (temperature-induced crystallization)-melting crystallites into pure NR system, in situ synchronic WAXD revealed the formation of low-oriented crystal in the initial deformation stage, which gradually evolves into highly oriented crystal at last. The low-oriented crystal is related to secondary folded-chain nucleation (N2) on the surface of residual TIC-melting crystallites (self-seeding), while newly formed highly oriented crystal is associated with N1. For the first time, the concept of "self-seeding" is innovatively applied to SIC process so that NR exhibits clear nucleation transition phenomenon. Further, theoretical computation of nucleation barrier in the special NR system well reflects that self-seeding has the role of both increasing critical strain of nucleation transition and decreasing onset strain of SIC, thus providing conditions for the observation. PMID:26258563

  2. Enhanced dispersion of multiwall carbon nanotubes in natural rubber latex nanocomposites by surfactants bearing phenyl groups.

    PubMed

    Mohamed, Azmi; Anas, Argo Khoirul; Bakar, Suriani Abu; Ardyani, Tretya; Zin, Wan Manshol W; Ibrahim, Sofian; Sagisaka, Masanobu; Brown, Paul; Eastoe, Julian

    2015-10-01

    Here is presented a systematic study of the dispersibility of multiwall carbon nanotubes (MWCNTs) in natural rubber latex (NR-latex) assisted by a series of single-, double-, and triple-sulfosuccinate anionic surfactants containing phenyl ring moieties. Optical polarising microscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman spectroscopy have been performed to obtain the dispersion-level profiles of the MWCNTs in the nanocomposites. Interestingly, a triple-chain, phenyl-containing surfactant, namely sodium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3-phenylpropoxy)carbonyl) pentane-2-sulfonate (TCPh), has a greater capacity the stabilisation of MWCNTs than a commercially available single-chain sodium dodecylbenzenesulfonate (SDBS) surfactant. TCPh provides significant enhancements in the electrical conductivity of nanocomposites, up to ∼10(-2) S cm(-1), as measured by a four-point probe instrument. These results have allowed compilation of a road map for the design of surfactant architectures capable of providing the homogeneous dispersion of MWCNTs required for the next generation of polymer-carbon-nanotube materials, specifically those used in aerospace technology. PMID:26070188

  3. Investigation of miscibility of p(3hydroxybutyrate-co-3hydroxyhexanoate) and epoxidized natural rubber blends

    NASA Astrophysics Data System (ADS)

    Akram, Faridah; Chan, Chin Han; Natarajan, Valliyappan David

    2015-08-01

    Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate [P(3HB-co-3HHx)] produced by C. necator PHB-4 harboring phaCcs from crude palm kernel oil with 21 mol% of 3-hydroxyhexanoate and epoxidized natural rubber with 25 mol% of epoxy content (ENR-25) were used to study the miscibility of the blends by attenuated total reflection-Fourier transform infrared (ATR-FTIR) and differential scanning calorimetry (DSC). The polymers used were purified and the blends were prepared by solution casting method. Nuclear magnetic resonance (NMR) spectra confirm the purity and molecular structures of P(3HB-co-3HHx) and ENR-25. FTIR spectra for different compositions of P(3HB-co-3HHx) and ENR-25 blends show absorbance change of the absorbance bands but with no significant shifting of the absorbance bands as the P(3HB-co-3HHx) content decreases, which shows that there is no intermolecular interaction between the parent polymer blends. On top of that, there are two Tgs present for the blends and both remain constant for different compositions which corresponds to the Tgs of the parent polymers. This indicates that the blends are immiscible.

  4. Preparation and characterization of potato starch nanocrystal reinforced natural rubber nanocomposites.

    PubMed

    Rajisha, K R; Maria, H J; Pothan, L A; Ahmad, Zakiah; Thomas, S

    2014-06-01

    Potato starch nanocrystals were found to serve as an effective reinforcing agent for natural rubber (NR). Starch nanocrystals were obtained by the sulfuric acid hydrolysis of potato starch granules. After mixing the latex and the starch nanocrystals, the resulting aqueous suspension was cast into film by solvent evaporation method. The composite samples were successfully prepared by varying filler loadings, using a colloidal suspension of starch nanocrystals and NR latex. The morphology of the nanocomposite prepared was analyzed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). FESEM analysis revealed the size and shape of the crystal and their homogeneous dispersion in the composites. The crystallinity of the nanocomposites was studied using XRD analysis which indicated an overall increase in crystallinity with filler content. The mechanical properties of the nanocomposites such as stress-strain behavior, tensile strength, tensile modulus and elongation at break were measured according to ASTM standards. The tensile strength and modulus of the composites were found to improve tremendously with increasing nanocrystal content. This dramatic increase observed can be attributed to the formation of starch nanocrystal network. This network immobilizes the polymer chains leading to an increase in the modulus and other mechanical properties. PMID:24657376

  5. Structural changes in the low-density polyethylene/natural rubber composites in the aqueous and soil media

    NASA Astrophysics Data System (ADS)

    Mastalygina, Elena E.; Varyan, Ivetta A.; Kolesnikova, Natalya N.; Popov, Anatoly A.

    2016-05-01

    The novel biodegradable materials based on polyethylene with different content of natural rubber have been developed. In this paper the regularities of changes in structure and properties of the composites under the influence of biological and non-biological factors have been investigated. High levels of biodegradability and satisfied mechanical properties of biocomposites, as well as the significant modification of the polyethylene crystalline phase in the composites affected by moisture and environmental factors have been determined.

  6. Heavy duty piezoresistivity induced strain sensing natural rubber/carbon black nanocomposites reinforced with different carbon nanofillers

    NASA Astrophysics Data System (ADS)

    He, Qingliang; Yuan, Tingting; Zhang, Xi; Guo, Shimei; Liu, Jingjing; Liu, Jiurong; Liu, Xinyu; Sun, Luyi; Wei, Suying; Guo, Zhanhu

    2014-09-01

    Durable piezoresistive effects of natural rubber nanocomposites have been demonstrated, i.e., with stable and reversible electrical resistance change within the tested 3000 cycles upon applying a small compressive strain (˜16.7%) under a relatively high frequency (0.5 Hz, 2 s/cycle). This unique function was achieved for the first time by combining carbon nanotubes and carbon nanofibers with natural rubber composites pretreated with carbon black. Even though the combination of different carbon nanomaterials, such as graphene nanosheets and carbon nanotubes, can improve the dispersion quality of both the nanostructures in solution or in polymer matrices, this type of synergistic effect between carbon nanotubes and carbon nanofibers in producing stable and reversible piezoresistive effect has been rarely reported. Besides, the strong reinforcement (compressive stress at a maximum strain of 16.7% was increased from 12.6 for untreated to 18.5 MPa for the natural rubber/carbon black composites treated with a combination of 1.0 wt% carbon nanotubes and 1.0 wt% carbon nanofibers) makes the as-prepared composites promising for heavy duty pressure sensors, i.e., healthy motion monitoring of industrial machinery vibrations.

  7. Multi-Scaled Microstructures in Natural Rubber Characterized by Synchrotron X-ray Scattering and Optical Microscopy

    SciTech Connect

    Toki , S.; Hsiao, B; Amnuaypornsri , S; Sakdapipanich, J; Tanaka, Y

    2008-01-01

    Multi-scaled microstructures induced by natural impurities (i.e., proteins, phospholipids, carbohydrates) in natural rubber (NR) were investigated by synchrotron small-angle X-ray scattering (SAXS), wide-angle X-ray diffraction (WAXD), and optical microscopy using several kinds of untreated and chemically treated un-vulcanized samples. These microstructures include large aggregates (size less than 50 m), well-defined crystals (size less than a few 10 m), and micelles (size much less than 10 m). In un-vulcanized NR samples, even though the concentrations of natural impurities are relatively low, the dispersion of these microstructures significantly affects the mechanical properties

  8. Tough Rubber.

    ERIC Educational Resources Information Center

    Schmid, Sue

    1994-01-01

    Describes the benefits of using rubber floor coverings in a gym's free-weight and cardiovascular equipment areas. Tips on purchasing a rubber floor are highlighted as is an annotated list of suppliers and their rubber flooring products. (GR)

  9. Antitumor activity of chemical modified natural compounds.

    PubMed

    de Oliveira, M M

    1991-01-01

    Search of new activity substances starting from chemotherapeutic agents, continuously appears in international literature. Perhaps this search has been done more frequently in the field of antitumor chemotherapy on account of the unsuccess in saving advanced stage patients. The new point in this matter during the last decade was computer aid in planning more rational drugs. In near future "the accessibility of super computers and emergence of computer net systems, will open new avenues to rational drug design" (Portoghese, P. S., J. Med. Chem. 1989, 32, 1). Unknown pharmacological active compounds synthetized by plants can be found even without this electronic devices, as traditional medicine has pointed out in many countries, and give rise to a new drug. These compounds used as found in nature or after chemical modifications have produced successful experimental medicaments as FAA, "flavone acetic acid" with good results as inhibitors of slow growing animal tumors currently in preclinical evaluation for human treatment. In this lecture some international contributions in the field of chemical modified compounds as antineoplastic drugs will be examined, particularly those done by Brazilian researches. PMID:1842015

  10. cis-Prenyltransferase and Polymer Analysis from a Natural Rubber Perspective.

    PubMed

    Kwon, M; Kwon, E-J G; Ro, D K

    2016-01-01

    Dolichol and natural rubber are representative cis-polyisoprenoids in primary and secondary metabolism, respectively. Their biosynthesis is catalyzed by cis-prenyltransferase (CPT) by sequential condensations of isopentenyl diphosphates (IPPs) to a priming molecule. Although prokaryotic CPTs have been well characterized, the mechanism of eukaryotic CPTs in cis-polyisoprene biosynthesis was only recently revealed. It was shown that eukaryotes have evolved a unique protein complex, comprised of CPT and CPT-binding protein (CBP), to synthesize cis-polyisoprenoids. In the context of this new discovery, we found discrepancies in literature for CPT or CBP biochemical assays and in vivo CPT complementation using rer2 (yeast CPT) yeast mutant. Our study here shows that rer2 revertants occur at a frequency that cannot be disregarded and are likely accountable for the results that cannot be explained by the CPT/CBP heteroprotein complex model. To make a stable mutant, SRT1 gene (secondary CPT expressed at a basal level in yeast) was additionally deleted in the rer2Δ mutant background. This stable rer2Δ srt1Δ strain was then used to individually or simultaneously express Arabidopsis CPT1 (AtCPT1, At2g17570) and CBP (AtLEW1, At1G11755). We found that the simultaneous expression of Arabidopsis CPT1 and AtLEW1 effectively complements the rer2Δ srt1Δ strain, whereas the individual expression of AtCPT1 alone or AtLEW1 alone failed to rescue the yeast mutant. Microsomes from the dual expresser showed an efficient incorporation of IPPs into cis-polyisoprenoid (30% in 2h). These results showed that the CPT/CBP heteroprotein complex model is valid in Arabidopsis thaliana. Experimental details of these results are described in this methodology paper. PMID:27480685

  11. Migration of BTEX and phthalates from natural rubber latex balloons obtained from the Sri Lankan market.

    PubMed

    Jayawardena, Imanda; Godakumbura, Pahan I; Prashantha, M A B

    2016-01-01

    The current study evaluates the migration of benzene, toluene, ethylbenzene, xylene (BTEX) and phthalates into artificial saliva from natural rubber latex (NRL) balloons available for sale in Sri Lanka. It was discovered that at least one BTEX compound migrated from almost all the brands. The migration of four phthalates; diethyl phthalate, dibutyl phthalate, di-isobutyl phthalate and butyl benzyl phthalate were also observed. Migratory levels of BTEX and phthalates in most of the balloon brands were above the permissible levels set by the European Union. Assessment of factors affecting the migratory levels indicated migration under active mouthing conditions and migration from the neck region of the balloons were significantly higher. The migratory levels were observed to decrease with storage time, and in certain brands the BTEX levels decreased below the permissible level. One-way ANOVA indicated no significant differences (p ≥ 0.05) in migratory levels of each individual compound within the same brand for both BTEX and phthalates. When compared among different brands, BTEX levels indicated significant differences (p ≤ 0.05), while phthalate levels were observed to not be significantly different (p ≥ 0.05). A significant difference was also observed (p ≤ 0.05) among the migratory levels of compounds under each test condition evaluated as factors affecting the migratory level. Furthermore, the solvent based colorants added to color the latex were found to be the source of BTEX and phthalates in the NRL balloons. PMID:26759759

  12. Syntheses, spectroscopic characterization, crystal structure and natural rubber vulcanization activity of new disulfides derived from sulfonyldithiocarbimates

    NASA Astrophysics Data System (ADS)

    Alves, Leandro de Carvalho; Rubinger, Mayura Marques Magalhães; Tavares, Eder do Couto; Janczak, Jan; Pacheco, Elen Beatriz Acordi Vasques; Visconte, Leila Lea Yuan; Oliveira, Marcelo Ribeiro Leite

    2013-09-01

    The compounds (Bu4N)2[(4-RC6H4SO2NCS2)2] [Bu4N = tetrabutylammonium cation; R = H (1), F (2), Cl (3) and Br (4)] and (Ph4P)2[(4-RC6H4SO2NCS2)2]ṡH2O [Ph4P = tetraphenylphosphonium cation and R = I (5)] were synthesized by the reaction of the potassium dithiocarbimates (4-RC6H4SO2NCS2K2ṡ2H2O) with I2 and Bu4NBr or Ph4PCl. The IR data were consistent with the formation of the dithiocarbimatodisulfides anions. The NMR spectra showed the expected signals for the cations and anions in a 2:1 proportion. The structures of compounds 1-5 were determined by the single crystal X-ray diffraction. The compounds 2, 3 and 4 are isostructural and crystallise in the centrosymmetric space group C2/c of the monoclinic system. Compound 1 crystallises in the monoclinic system in the space group of P21/n and the compound 5 crystallises in the centrosymmetric space group P-1 of the triclinic system. The complex anions of compounds 2, 3 and 4 exhibit similar conformations having twofold symmetry, while in 1 and 5 the anions exhibit C1 symmetry. The activity of the new compounds in the vulcanization of the natural rubber was evaluated and compared to the commercial accelerators ZDMC, TBBS and TMTD. These studies confirm that the sulfonyldithiocarbimato disulfides anions are new vulcanization accelerators, being slower than the commercial accelerators, but producing a greater degree of crosslinking, and scorch time values compatible with good processing safety for industrial applications. The mechanical properties, stress and tear resistances were determined and compared to those obtained with the commercial accelerators.

  13. Shell structure of natural rubber particles: evidence of chemical stratification by electrokinetics and cryo-TEM.

    PubMed

    Rochette, Christophe N; Crassous, Jérôme J; Drechsler, Markus; Gaboriaud, Fabien; Eloy, Marie; de Gaudemaris, Benoît; Duval, Jérôme F L

    2013-11-26

    The interfacial structure of natural rubber (NR) colloids is investigated by means of cryogenic transmission electron microscopy (cryo-TEM) and electrokinetics over a broad range of KNO3 electrolyte concentrations (4-300 mM) and pH values (1-8). The asymptotic plateau value reached by NR electrophoretic mobility (μ) in the thin double layer limit supports the presence of a soft (ion- and water-permeable) polyelectrolytic type of layer located at the periphery of the NR particles. This property is confirmed by the analysis of the electron density profile obtained from cryo-TEM that evidences a ∼2-4 nm thick corona surrounding the NR polyisoprene core. The dependence of μ on pH and salt concentration is further marked by a dramatic decrease of the point of zero electrophoretic mobility (PZM) from 3.6 to 0.8 with increasing electrolyte concentration in the range 4-300 mM. Using a recent theory for electrohydrodynamics of soft multilayered particles, this "anomalous" dependence of the PZM on electrolyte concentration is shown to be consistent with a radial organization of anionic and cationic groups across the peripheral NR structure. The NR electrokinetic response in the pH range 1-8 is indeed found to be equivalent to that of particles surrounded by a positively charged ∼3.5 nm thick layer (mean dissociation pK ∼ 4.2) supporting a thin and negatively charged outermost layer (0.6 nm in thickness, pK ∼ 0.7). Altogether, the strong dependence of the PZM on electrolyte concentration suggests that the electrostatic properties of the outer peripheral region of the NR shell are mediated by lipidic residues protruding from a shell containing a significant amount of protein-like charges. This proposed NR shell interfacial structure questions previously reported NR representations according to which the shell consists of either a fully mixed lipid-protein layer, or a layer of phospholipids residing exclusively beneath an outer proteic film. PMID:24152085

  14. Allergen profiles of natural rubber latex (NRL) proteins on gloves and glove powders.

    PubMed

    Tomazic-Jezic, Vesna J; Sanchez, B A

    2005-01-01

    The contributing role of glove powder in sensitization to natural rubber latex (NRL) proteins has been well documented in laboratory studies and through clinical evaluations. However, the quantitative relationship of the respiratory and topical exposures in the sensitization process remains unknown because the relative levels of protein on the glove powders in relation to the total levels of protein on NRL gloves have not been determined. In NRL allergens--Hev b 1, Hev b 3, Hev b 5, and Hev b 6.02--on randomly selected surgical and examination NRL gloves. We also examined the binding pattern of the four allergens to several glove powders that showed a different affinity to NRL proteins. The level of powder-bound protein was determined by the ELISA Inhibition Assay (ASTM D6499 standard method). Two cross-linked corn starch powders, one sample of cooking corn starch and one oat starch sample, were exposed to ammoniated (AL) or nonammoniated (NAL) raw NRL protein extracts. The levels of individual allergens were determined using the NRL allergen kit. In the NRL glove extracts we observed a wide range in the total allergen levels and a great diversity in the proportion of the four allergens. On the other hand, the evaluated starches had similar ratios of four individual allergens, regardless of the differences in their total allergen levels. The exposure of starches to NRL proteins with different allergen profiles did not affect the allergen ratio. All samples demonstrated a selective affinity for binding Hev b 1 and Hev b 5 allergens and a lesser affinity for the Hev b 6.02 allergen. Allergen Hev b 6.02 made up about 60% of the total allergen in the NAL extract, but only 12-30% of Hev b 6.02 was bound to starches. In contrast, there was only 3-7% of Hev b 1 allergen in the NAL extract, but powders had 35-45% of Hev b 1. These findings indicate that allergenic properties of NRL gloves and respective glove powders may be different. PMID:15777165

  15. Application of Image And X-Ray Microtomography Technique To Quantify Filler Distribution In Thermoplastic-Natural Rubber Blend Composites

    SciTech Connect

    Ahmad, Sahrim; Rasid, Rozaidi; Mouad, A. T.; Aziz Mohamed, A.; Abdullah, Jaafar; Dahlan, M.; Mohamad, Mahathir; Jamro, Rafhayudi; Hamzah Harun, M.; Yazid, Hafizal; Abdullah, W. Saffiey W.

    2010-01-05

    X-ray microtomography and ImageJ 1.39 u is used as a tool to quantify volume percentage of B{sub 4}C as fillers in thermoplastic-natural rubber blend composites. The use of percentage of area occupied by fillers as obtain from ImageJ from the microtomography sliced images enables the proposed technique to easily obtain the amount volume percentage of B{sub 4}C in the composite non-destructively. Comparison with other technique such as density measurement and chemical analysis proves the proposed technique as one of the promising approach.

  16. Climate and natural production of rubber ( Hevea brasiliensis) in Xishuangbanna, southern part of Yunnan province, China

    NASA Astrophysics Data System (ADS)

    Jiang, Ailiang

    1988-12-01

    According to the author's and his collaborators' investigations, the climate influences the growth of rubber trees ( Hevea brasiliensis) in Xishuangbanna, the southern part of Yunnan Province, China, in at least four aspects: (1) The yield of latex per tapping and the final yield of dry rubber per tree per year or per unit area per year; (2) the growth rate, as expressed by increment of girth in cm; (3) the survival during the over-wintering period; (4) the initiation or suppression of certain diseases; In this paper the author would like to describe the influence of climatic elements on yield of latex and on survival during the over-wintering period. As for the other two aspects, only general comments are given.

  17. Organic acids and protein compounds causing the photoluminescence properties of natural rubber membranes and the quenching phenomena from Au nanoparticle incorporation.

    PubMed

    Cabrera, Flávio C; Agostini, Deuber L S; Dos Santos, Renivaldo J; Guimarães, Francisco E G; Guerrero, Ariel R; Aroca, Ricardo F; Job, Aldo E

    2014-12-01

    Natural rubber membranes were fabricated using latex from Hevea brasiliensis trees (clone RRIM 600) by casting, and controlling the time and temperature of thermal treatment. Three temperatures were used: 65, 80 and 120 °C and the corresponding annealing times of 6, 8, 10 and 12 h. The centrifugation of the latex produces the constituent phases: solid rubber (F1), serum or protein components (F2) and bottom fraction (F3). The photoluminescence properties could be correlated with organic acid components of latex. Natural rubber membranes were used as the active substrate (reducing agent) for the incorporation of colloidal Au nanoparticles synthesized by in situ reduction at different times. The intensity of photoluminescence bands assigned to the natural rubber decreases with the increase in amount of nanoparticles present on the membrane surface. It can be assumed that Au nanoparticles may be formed by reduction of the Au cation reacting with functional groups that are directly related to photoluminescence properties. However, the quenching of fluorescence may be attributed to the formation of a large amount of metal nanostructures on the natural rubber surface. PMID:24760547

  18. Effect of epoxidation level on thermal properties and ionic conductivity of epoxidized natural rubber solid polymer nanocomposite electrolytes

    NASA Astrophysics Data System (ADS)

    Harun, Fatin; Chan, Chin Han; Sim, Lai Har; Winie, Tan; Zainal, Nurul Fatahah Asyqin

    2015-08-01

    Effect of epoxide content on the thermal and conductivity properties of epoxidized natural rubber (ENR) solid polymer nanocomposite electrolytes was investigated. Commercial available epoxidized natural rubber having 25 (ENR25) and 50 mole% (ENR50) epoxide, respectively were incorporated with lithium perchlorate (LiClO4) salt and titanium dioxide (TiO2) nanofiller via solution casting method. The solid polymer nanocomposite electrolytes were characterized by differential scanning calorimetry (DSC) and impedance spectroscopy (IS) for their thermal properties and conductivity, respectively. It was evident that introduction of LiClO4 causes a greater increase in glass transition temperature (Tg) and ionic conductivity of ENR50 as compared to ENR25. Upon addition of TiO2 in ENR/LiClO4 system, a remarkable Tg elevation was observed for both ENRs where ENR50 reveals a more pronounced changes. It is interesting to note that they exhibit different phenomenon in ionic conductivity with TiO2 loading where ENR25 shows enhancement of conductivity while ENR50 shows declination.

  19. Effect of epoxidation level on thermal properties and ionic conductivity of epoxidized natural rubber solid polymer nanocomposite electrolytes

    SciTech Connect

    Harun, Fatin; Chan, Chin Han; Winie, Tan; Sim, Lai Har; Zainal, Nurul Fatahah Asyqin

    2015-08-28

    Effect of epoxide content on the thermal and conductivity properties of epoxidized natural rubber (ENR) solid polymer nanocomposite electrolytes was investigated. Commercial available epoxidized natural rubber having 25 (ENR25) and 50 mole% (ENR50) epoxide, respectively were incorporated with lithium perchlorate (LiClO{sub 4}) salt and titanium dioxide (TiO{sub 2}) nanofiller via solution casting method. The solid polymer nanocomposite electrolytes were characterized by differential scanning calorimetry (DSC) and impedance spectroscopy (IS) for their thermal properties and conductivity, respectively. It was evident that introduction of LiClO{sub 4} causes a greater increase in glass transition temperature (T{sub g}) and ionic conductivity of ENR50 as compared to ENR25. Upon addition of TiO{sub 2} in ENR/LiClO{sub 4} system, a remarkable T{sub g} elevation was observed for both ENRs where ENR50 reveals a more pronounced changes. It is interesting to note that they exhibit different phenomenon in ionic conductivity with TiO{sub 2} loading where ENR25 shows enhancement of conductivity while ENR50 shows declination.

  20. Biocomposites from Natural Rubber: Synergistic Effects of Functionalized Cellulose Nanocrystals as Both Reinforcing and Cross-Linking Agents via Free-Radical Thiol-ene Chemistry.

    PubMed

    Parambath Kanoth, Bipinbal; Claudino, Mauro; Johansson, Mats; Berglund, Lars A; Zhou, Qi

    2015-08-01

    Natural rubber/cellulose nanocrystals (NR/CNCs) form true biocomposites from renewable resources and are demonstrated to show significantly improved thermo-mechanical properties and reduced stress-softening. The nanocomposites were prepared from chemically functionalized CNCs bearing thiols. CNCs served as both reinforcing and cross-linking agents in the NR matrix, and the study was designed to prove the cross-linking function of modified CNCs. CNCs were prepared from cotton, and the cross-linkable mercapto-groups were introduced onto the surface of CNCs by esterification. Nanocomposite films were prepared by dispersing the modified CNCs (m-CNCs) in NR matrix by solution casting. The cross-links at the filler-matrix (m-CNCs-NR) interface were generated by photochemically initiated thiol-ene reactions as monitored by real-time FTIR analysis. The synergistic effects of reinforcement and chemical cross-linking at the m-CNCs-NR interface on structure, thermo-mechanical, and stress-softening behavior were investigated. Methods included field emission scanning electron microscopy (FE-SEM), swelling tests, dynamic mechanical analysis, and tensile tests. Compared to biocomposites from NR with unmodified CNCs, the NR/m-CNCs nanocomposites showed 2.4-fold increase in tensile strength, 1.6-fold increase in strain-to-failure, and 2.9-fold increase in work-of-fracture at 10 wt % of m-CNCs in NR. PMID:26151647

  1. Perceived naturalness and acceptance of genetically modified food.

    PubMed

    Tenbült, Petra; de Vries, Nanne K; Dreezens, Ellen; Martijn, Carolien

    2005-08-01

    This study examines people's acceptance of genetically modified (GM) food. Results suggest that GM acceptance depends most on how natural the genetically modified product is perceived and not directly on how natural the non-GM product is seen. A GM product that is perceived as more natural is more likely to be accepted than a GM product that is perceived as less natural. The extent to which GM affects the perceived naturalness of a product partly depends on the kind of product. PMID:15896875

  2. New application of crystalline cellulose in rubber composites

    NASA Astrophysics Data System (ADS)

    Bai, Wen

    Rubber without reinforcement has limited applications. The strength of reinforced rubber composites can be ten times stronger than that of unreinforced rubbers. Therefore, rubber composites are widely used in various applications ranging from automobile tires to seals, valves, and gaskets because of their excellent mechanical elastic properties. Silica and carbon black are the two most commonly used reinforcing materials in rubber tires. They are derived from non-renewable materials and are expensive. Silica also contributes to a large amount of ash when used tires are disposed of by incineration. There is a need for a new reinforcing filler that is inexpensive, renewable and easily disposable. Cellulose is the most abundant natural polymer. Native cellulose includes crystalline regions and amorphous regions. Crystalline cellulose can be obtained by removing the amorphous regions with the acid hydrolysis of cellulose because the amorphous cellulose can be hydrolyzed faster than crystalline cellulose. We recently discovered that the partial replacement of silica with microcrystalline cellulose (MCC) provided numerous benefits: (1) low energy consumption for compounding, (2) good processability, (3) strong tensile properties, (4) good heat resistance, and (5) potential for good fuel efficiency in the application of rubber tires. Strong bonding between fillers and a rubber matrix is essential for imparting rubber composites with the desired properties for many specific applications. The bonding between hydrophilic MCC and the hydrophobic rubber matrix is weak and can be improved by addition of a coupling agent or surface modifications of MCC. In this study, MCC was surface-modified with acryloyl chloride or alkenyl ketene dimer (AnKD) to form acrylated MCC (A-MCC) and AnKD-modified MCC (AnKD-MCC). The surface modifications of MCC did not change the integrity and mechanical properties of MCC, but provided functional groups that were able to form covalent linkages with

  3. Evaluation and performance based mix design of rubber modified mixtures: Laboratory evaluation of asphalt concrete mixtures using waste tires. Final report

    SciTech Connect

    Goulias, D.G.; Ali, A.H.M.

    1997-02-01

    New Jersey Department of Transportation has been investigating the use of rubber modified materials over the last few years with the design and use of dense and gap graded mixtures, and in some cases the incorporation of RAP materials, in selected projects. While the short term field performance of these materials is satisfactory, their long term performance is unknown. These mixtures were designed with the traditional Marshall mixture design method, and thus is was not considered design criteria related to mixture behavior and performance into mixture selection. The main objective of this study is the development of a mixture design methodology for rubber modified materials that considers mixture behavior and performance. In order to achieve this objective researchers conducted a laboratory investigation which was able to evaluate mixture properties that can be related to mixture performance, (in terms of rutting, low temperature cracking, and fatigue), and simulating the actual field loading conditions that the material is being exposed to. The possibility of coupling the traditional Marshall mix design method with parameters related to mixture behavior and performance was investigated since this technique has been used over the years by the agency, and the necessary testing apparatus is available to both the agency and material laboratories. The SHRP SUPERPAVE mix design methodology was reviewed and considered in this study for the development of an integrated performance based design procedure. However, its applicability and use on routine bases was not considered at this time since it requires specific equipment with ongoing evaluation for its repeatability and precision. Finally, for the conduct of this investigation materials and mixtures used by NJDOT in rubber modified paving projects were used.

  4. New Insights into the Relationship Between Network Structure and Strain Induced Crystallization in Unvolcanized Natural Rubber by Synchrotron X-ray Diffraction

    SciTech Connect

    Toki, S.; Hsiao, B; Amnuaypornsri, S; Sakdapipanich, J

    2009-01-01

    The relationship between the network structure and strain-induced crystallization in un-vulcanized as well as vulcanized natural rubbers (NR) and synthetic poly-isoprene rubbers (IR) was investigated via synchrotron wide-angle X-ray diffraction (WAXD) technique. It was found that the presence of a naturally occurring network structure formed by natural components in un-vulcanized NR significantly facilitates strain-induced crystallization and enhances modulus and tensile strength. The stress-strain relation in vulcanized NR is due to the combined effect of chemical and naturally occurring networks. The weakness of naturally occurring network against stress and temperature suggests that vulcanized NR has additional relaxation mechanism due to naturally occurring network. The superior mechanical properties in NR compared with IR are mainly due to the existence of naturally occurring network structure.

  5. New Insights into Chain Order Dynamics and Structural Development in Sulfur-Vulcanized Natural Rubber Latex using Multiple Quantum NMR and Synchrotron X-Ray Diffraction

    NASA Astrophysics Data System (ADS)

    Che, Justin; Toki, Shigeyuki; Valentin, Juan; Brasero, Justo; Rong, Lixia; Hsiao, Benjamin S.

    2012-02-01

    Network structure, chain dynamics, and structural development in sulfur-vulcanized natural rubber latex were studied by Multiple-Quantum (MQ) NMR and synchrotron x-ray scattering. Three important processes that can influence rubber network structure and its overall mechanical properties were the main focus and analyzed by both of these techniques: pre-vulcanization, drying, and post-vulcanization. MQ NMR experiments can provide quantitative information regarding networks at very small length scales, including network defects, number of cross-links, and spatial distribution of cross-links. Structural development in natural rubber was studied under uniaxial deformation by in-situ synchrotron x-ray diffraction, which can provide information on network structures at much larger length scales. Molecular orientation and strain-induced crystallization was analyzed by both stress-strain relations and wide-angle x-ray diffraction (WAXD). The morphology of the latex rubber particle during deformation was analyzed by small-angle x-ray scattering (SAXS). The combination of these techniques can provide a considerable amount of information regarding rubber network structure.

  6. Performance of sand and shredded rubber tire mixture as a natural base isolator for earthquake protection

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, Srijit; Sengupta, Aniruddha; Reddy, G. R.

    2015-12-01

    The performance of a well-designed layer of sand, and composites like layer of sand mixed with shredded rubber tire (RSM) as low cost base isolators, is studied in shake table tests in the laboratory. The building foundation is modeled by a 200 mm by 200 mm and 40 mm thick rigid plexi-glass block. The block is placed in the middle of a 1m by 1m tank filled with sand. The selected base isolator is placed between the block and the sand foundation. Accelerometers are placed on top of the footing and foundation sand layer. The displacement of the footing is also measured by LVDT. The whole setup is mounted on a shake table and subjected to sinusoidal motions with varying amplitude and frequency. Sand is found to be effective only at very high amplitude (> 0.65 g) of motions. The performance of a composite consisting of sand and 50% shredded rubber tire placed under the footing is found to be most promising as a low-cost effective base isolator.

  7. PALS and DSC measurements in 8 MeV electron irradiated natural rubber filled with different fillers

    NASA Astrophysics Data System (ADS)

    Mandal, Arunava; Pan, Sandip; Roychowdhury, Anirban; Sengupta, Asmita

    2015-10-01

    The effect of high energy electron irradiation on the microstructure and thermal properties of natural rubber (NR) filled with different fillers at different concentrations are studied. The samples are irradiated with 8 MeV electron beam to a total dose of 100 KGy. The change in free volume size and specific heat due to addition of fillers and irradiation are studied using positron annihilation lifetime spectroscopy (PALS) and differential scanning calorimetry (DSC) respectively. The Positron lifetime spectra are de-convoluted into two components. The longer lived component (τo-Ps) signifies the pick-off annihilation of ortho-positronium (o-Ps) at free volume site which may be related to the radius of the free volume holes. It is observed that the specific heat (Cp) and free volume size are all affected by both irradiation and addition of fillers.

  8. Mechanical properties of natural rubber nanocomposites reinforced with high aspect ratio cellulose nanocrystals isolated from soy hulls.

    PubMed

    Flauzino Neto, Wilson Pires; Mariano, Marcos; da Silva, Ingrid Souza Vieira; Silvério, Hudson Alves; Putaux, Jean-Luc; Otaguro, Harumi; Pasquini, Daniel; Dufresne, Alain

    2016-11-20

    Cellulose nanocrystals (CNCs) were isolated from soy hulls by acid sulfuric hydrolysis. The resulting CNCs were characterized using TEM, AFM, WAXS, elemental analysis and TGA. The CNCs have a high crystallinity, specific surface area and aspect ratio. The aspect ratio (around 100) is the largest ever reported in the literature for a plant cellulose source. These CNCs were used as a reinforcing phase to prepare nanocomposite films by casting/evaporation using natural rubber as matrix. The mechanical properties were studied in both the linear and non-linear ranges. The reinforcing effect was higher than the one observed for CNCs extracted from other sources. It may be assigned not only to the high aspect ratio of these CNCs but also to the stiffness of the percolating nanoparticle network formed within the polymer matrix. Moreover, the sedimentation of CNCs during the evaporation step was found to play a crucial role on the mechanical properties. PMID:27561481

  9. Impact of interleukin-13 and -18 promoter polymorphisms in health care workers with natural rubber latex allergy.

    PubMed

    Rihs, Hans-Peter; Lotz, Anne; Ruëff, Franziska; Landt, Olfert; Brüning, Thomas; Raulf-Heimsoth, Monika

    2012-01-01

    It is a matter of debate whether single nucleotide polymorphisms (SNP) in the promoter region of interleukin (IL)-13, an IgE regulator, and IL-18, an inducer of immune responses, modulating the respective protein expression, are accompanied by an increased risk of atopy, allergic asthma, and total IgE levels. The suspected associations were noted in health care workers (HCW) with and without latex allergy. IL-13 (-1055C>T) and three IL-18 (-656T>G, -607C>A, -137G>C) SNP were studied in 523 HCW with natural rubber latex (NRL) exposure and diagnosis in the late 1990s. Three hundred and thirty-four HCW displayed NRL sensitization and allergic symptoms, 93 with latex-allergic asthma, and 189 HCW with neither symptoms nor NRL sensitization. SNP analyses were performed by real-time polymerase chain reaction (PCR) using newly developed LightCycler assays. Analysis of IL-13 -1055C>T by analysis of variance (ANOVA) revealed significantly elevated total IgE levels in HCW carrying the CT or TT variant compared with the CC variant. None of the studied SNP showed an association with NRL-specific IgE. The IL-18 variants -656GG and -607CC displayed 99.5% linkage disequilibrium. Frequencies of alleles -656GG and -607CC were elevated in HCW with NRL asthma (48.4%) compared with HCW without symptoms (37.6%). In contrast, IL-18 -137G>C variants displayed an overall homogenous distribution. The association between the IL-13 -1055T allele and elevated total IgE levels confirms the role of a genetic background for total IgE regulation. The studied IL-18 SNP demonstrated no significant association with the clinical outcome, total IgE, or specific IgE in HCW with natural rubber latex allergy. PMID:22686311

  10. Multilayer graphene rubber nanocomposites

    NASA Astrophysics Data System (ADS)

    Schartel, Bernhard; Frasca, Daniele; Schulze, Dietmar; Wachtendorf, Volker; Krafft, Bernd; Morys, Michael; Böhning, Martin; Rybak, Thomas

    2016-05-01

    Multilayer Graphene (MLG), a nanoparticle with a specific surface of BET = 250 m2/g and thus made of only approximately 10 graphene sheets, is proposed as a nanofiller for rubbers. When homogenously dispersed, it works at low loadings enabling the replacement of carbon black (CB), increase in efficiency, or reduction in filler concentration. Actually the appropriate preparation yielded nanocomposites in which just 3 phr are sufficient to significantly improve the rheological, curing and mechanical properties of different rubbers, as shown for Chlorine-Isobutylene-Isoprene Rubber (CIIR), Nitrile-Butadiene Rubber (NBR), Natural Rubber (NR), and Styrene-Butadiene Rubber (SBR). A mere 3 phr of MLG tripled the Young's modulus of CIIR, an effect equivalent to 20 phr of carbon black. Similar equivalents are observed for MLG/CB mixtures. MLG reduces gas permeability, increases thermal and electrical conductivities, and retards fire behavior. The later shown by the reduction in heat release rate in the cone calorimeter. The higher the nanofiller concentration is (3 phr, 5 phr, and 10 phr was investigated), the greater the improvement in the properties of the nanocomposites. Moreover, the MLG nanocomposites improve stability of mechanical properties against weathering. An increase in UV-absorption as well as a pronounced radical scavenging are proposed and were proved experimentally. To sum up, MLG is interesting as a multifunctional nanofiller and seems to be quite ready for rubber development.

  11. Satellite based remote sensing technique as a tool for real time monitoring of leaf retention in natural rubber plantations affected by abnormal leaf fall disease

    NASA Astrophysics Data System (ADS)

    Pradeep, B.; Meti, S.; James, J.

    2014-11-01

    Most parts of the traditional natural rubber growing regions of India, extending from Kanyakumari district of Tamil Nadu in the South to Kasaragod district of Kerala in the North received excess and prolonged rains during 2013. This led to severe incidence of Abnormal Leaf Fall (ALF) disease caused by the fungus, Phytophthora sp. The present study demonstrated the first time use of satellite remote sensing technique to monitor ALF disease by estimating Leaf Area Index (LAI) in natural rubber holdings in near real time. Leaf retention was monitored in between April and December 2012 and 2013 by estimating LAI using MODIS 15A2 product covering rubber holdings spread across all districts in the traditional rubber growing region of the country that was mapped using Resourcesat LISS III 2012 and 2013 data. It was found that as the monsoon advanced, LAI decreased substantially in both years, but the reduction was much more substantial and prolonged in many districts during 2013 than 2012 reflecting increased leaf fall due to ALF disease in 2013. The decline was more pronounced in central and northern Kerala than in the South. Kanyakumari district of Tamil Nadu is generally known to be free from ALF disease, but there was considerable leaf loss due to ALF in June 2012 and June and July 2013 even as the monsoon was unusually severe in 2013. Weighted mean LAI during for the entire period of April to December was estimated as a weighted average of LAI and per cent of total area under rubber in each district in the study area for the two years. This was markedly less in 2013 than 2012. The implications of poor leaf retention for biomass production (net primary productivity), carbon sequestration and rubber yield are discussed.

  12. Airborne exposures to PAH and PM2.5 particles for road paving workers applying conventional asphalt and crumb rubber modified asphalt.

    PubMed

    Watts, R R; Wallingford, K M; Williams, R W; House, D E; Lewtas, J

    1998-01-01

    Personal exposure monitoring was conducted for road paving workers in three states. A research objective was to characterize and compare occupational exposures to fine respirable particles (< 2.5 microns) and particle-bound polycyclic aromatic hydrocarbons (PAHs) for road paving workers applying conventional (petroleum derived) asphalt and asphalt containing crumb rubber from shredded tires. Workers not exposed to asphalt fume were also included for comparison (to support the biomarker component of this study). The rubber content of the crumb rubber modified (CRM) asphalt at the three study sites was 12, 15, and 20%. A comparison of some specific job categories from two sites indicates greater potential carcinogenic PAH exposures during CRM asphalt work, however, the site with the greatest overall exposures did not indicate any differences for specific jobs. A statistical analysis of means for fine particle, pyrene and total carcinogenic PAH personal exposure shows, with two exceptions, there were no differences in exposures for these three measurement variables. One site shows significantly elevated pyrene exposure for CRM asphalt workers and another site similarly shows greater carcinogenic PAH exposure for CRM asphalt workers. Conventional and CRM asphalt worker airborne exposures to the PAH carcinogen marker, BaP, were very low with concentrations comparable to ambient air in many cities. However, this study demonstrates that asphalt road paving workers are exposed to elevated airborne concentrations of a group of unknown compounds that likely consist of the carcinogenic PAHs benz(a)anthracene, chrysene and methylated derivatives of both. The research described in this article has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. PMID:9577752

  13. Rubber linings answer to many problems

    SciTech Connect

    Mehra, L.

    1998-12-31

    The uses of rubber linings in different fields industries are discussed.The physical properties of rubber both natural and synthetic rubber are listed and their importance is evaluated. The aging of rubber is discussed in detail, including effects of temperature on aging of rubber. By virtue of its inherent elasticity and chemical resistance, rubber linings have found many uses in the protection of mining equipment, water treatment tanks and vessels, flue gas desulfurization equipment in power plants and varied process and storage vessels in chemical industries. Rubber has found extensive use in civil engineering field as expansion joints and bladders in dams. Electrical resistance of rubber is useful for its application as an insulating material. Rubber is chemically resistant to acids, alkalies and many salt solutions. Rubber linings are therefore used for protection of steel against these acids, alkalies or salt solutions. The extreme elasticity of rubber has been found useful in its application as a lining material in areas subject to high abrasion. Frequently rubber linings are the linings of choice when a combination of abrasion and chemical attack are to be protected against. Constantly, new formulations of rubber lining compounds are being developed just as new chemical processes are being made. The flexibility of compounding and the relative ease of putting layers of different rubber formulations together in multilayered formulations of rubber lining compounds is leading to new uses of this lining material.

  14. Epoxidised Natural Rubber Based Composite Polymer Electrolyte Systems For Use In Electrochemical Device Applications

    SciTech Connect

    Idris, Razali; Tasnim, Anis; Mahbor, Kamisah Mohamad; Hakim, Mas Rosemal; Mohd, Dahlan Hj.; Ghazali, Zulkafli

    2009-09-14

    Composite polymer electrolyte (CPE) comprising epoxy-fimctionalized rubber (ENR), HDDA monomer, mixed plasticizer-propylene carbonate/ethylene carbonate, silica filler and lithium bis(trifluoromethanesulfonylimide), Li[(CF{sub 3}SO{sub 2}){sub 2}N]have been prepared using photo-induced polymerization by UV irradiation technique. The irradiated samples of filled and non-filled silica of composites electrolytes have formed dry solid-flexible and transparent films in the self-constructed Teflon mould. Thermal behaviors, FTIR, morphology and ionic conductivity were performed on such ENR based PE polymer composites having varied compositions. The thermal stability has improved slightly in the temperature range 120-200 deg. C with optimized composition. FTIR measurements data revealed that the interaction of lithium with the epoxy groups of the un-bonded electrons within polymer occurred. The results suggest that the variation of conductivity with temperature indicates that the silica filled composite has achieved optimal ionic conductivity 10{sup -4} S cm{sup -1} and retained high percent of plasticizer. The ionic conductivity behavior of the silica-filled ENR based composite polymer electrolyte is consistent at elevated temperature compared to non-filled CPE system. This finding opens a new pathway for further investigation to diffusion of ions in the complex polymer electrolyte systems.

  15. A polymeric flame retardant additive for rubbers

    SciTech Connect

    Ghosh, S.N.; Maiti, S.

    1993-12-31

    Synthesis of a polyphosphonate by the interfacial polymerization of bisphenol-A (BPA) and dichloro-phenyl phosphine oxide (DCPO) using cetyltrimethyl ammonium chloride (TMAC) as phase transfer catalyst (PTC) was reported. The polyphosphonate was characterized by elemental analysis, IR, TGA, DSC and 1H-NMR spectroscopy. The flame retardancy of the polymer was done by OI study. The polymer was used as a fire retardant additive to rubbers such as natural rubber (NR), styrene-butadiene rubber(SBR), nitrile rubber (NBR) and chloroprene rubber (CR). The efficiency of the fire retardant property of this additive was determined by LOI measurements of the various rubber samples.

  16. Do natural rubber latex condoms pose a risk to aquatic systems?

    PubMed

    Lambert, Scott; Johnson, Catherine; Keller, Virginie D J; Sinclair, Chris J; Williams, Richard J; Boxall, Alistair B A

    2013-12-01

    The presence and potential adverse effects of plastic-polymers in the environment are receiving increasing attention in the popular and scientific press. However, quantifying emissions, exposure and effects of these materials remains a challenge. This paper describes the application of a questionnaire survey to quantify emissions of condom material from the domestic household to the sewage waste stream. Condoms are an important mainstay for birth control and the reduction of sexually transmitted infections. Survey participants were estimated to flush condoms down the toilet 2.96% of the time, and emissions were calculated as 0.99 mg of condom material per person per day. Using information on screening efficiencies at sewage treatment plants, the questionnaire data was combined with a GIS-based water quality model (LF2000-WQX) to predicted environmental concentrations (PEC) in a UK river basin catchment. Annual average PECs of condom material were 0.08-0.2 μg L(-1), under the model scenario used. To put these PECs into context, rubber latex condom material was degraded in outdoor microcosms. This resulted in the formation of a complex mixture of substances including chemical degradation products and particles in the nano range. The direct effects of the degradation mixture were investigated using two freshwater organisms with different life cycle traits, the water column crustacean Daphnia magna and the sediment-dwelling larval of Chironomus riparius. Ecotoxicity tests investigated both acute and chronic endpoints and were shown to exhibit no toxic effects. This precluded the derivation of a genuine no-effect concentration. Hence, the results suggest that limited risk to invertebrates is associated with latex condom degradation products to the organisms tested. Future studies should extend this risk framework to assess risks of condoms to other taxonomic groups as well as the risks of other polymer materials. PMID:24162606

  17. Rubber Reclamation

    ERIC Educational Resources Information Center

    Williams, Kathryn R.

    2007-01-01

    The safety and health hazards related to recycling of used rubber, due to the scarcity and high price of virgin rubber are reported. Various threats like stagnant water pools trapped in tires leading to diseases and ignited tires, which become very difficult to extinguish and generating smoke that is extremely detrimental to the environment, have…

  18. Surface Modification of Fillers and Curatives by Plasma Polymerization for Enhanced Performance of Single Rubbers and Dissimilar Rubber/Rubber Blends

    NASA Astrophysics Data System (ADS)

    Noordermeer, J. W. M.; Datta, R. N.; Dierkes, W. K.; Guo, R.; Mathew, T.; Talma, A. G.; Tiwari, M.; van Ooij, W.

    Plasma polymerization is a technique for modifying the surface characteristics of fillers and curatives for rubber from essentially polar to nonpolar. Acetylene, thiophene, and pyrrole are employed to modify silica and carbon black reinforcing fillers. Silica is easy to modify because its surface contains siloxane and silanol species. On carbon black, only a limited amount of plasma deposition takes place, due to its nonreactive nature. Oxidized gas blacks, with larger oxygen functionality, and particularly carbon black left over from fullerene production, show substantial plasma deposition. Also, carbon/silica dual-phase fillers react well because the silica content is reactive. Elemental sulfur, the well-known vulcanization agent for rubbers, can also be modified reasonably well.

  19. The removal of bacteria by modified natural zeolites.

    PubMed

    Milán, Z; de Las Pozas, C; Cruz, M; Borja, R; Sánchez, E; Ilangovan, K; Espinosa, Y; Luna, B

    2001-01-01

    The removal effect of natural and modified zeolites containing different heavy metals (Ni2+, Zn2+, Fe3+ and Cu2+) on pure cultures of Escherichia coli and Staphylococcus aureus in a solid medium was evaluated in this work. These experiments were carried out in a continuous mode treating municipal wastewater. Faecal coliform species and Pseudomonas aeruginosa were identified. The rate constants of heavy metal lixiviation were determined using a first order kinetic model. The removal effect of modified natural zeolites in both a solid medium and in continuous mode showed an increased elimination of the bacterial population. The results established a decreasing order of the removal effect as follows: Cu2+ > Fe3+ > Zn2+ > Ni2+. The best performance of columns was obtained for inlet bacterial concentrations below 10(6) cells/100 ml. Most of the identified bacterial species were affected by copper modified zeolites, although Serratia marcescens presented the highest sensitivity and Klebsiella pneumoniae the greatest resistance. PMID:11501306

  20. Observations made during stretching, tearing and failure of NR (natural rubber) and SBR (styrene-butadiene rubber) loaded with various amounts of carbon black

    SciTech Connect

    Goldberg, A.; Lesuer, D.R.; Patt, J.

    1988-02-01

    In order to effectively utilize fractography as an aid in identifying the influence of material and service (or test) parameters on material properties, one must first understand the origin of the morphological features developed during the tearing and fracturing of these elastomers. At our laboratory, we have made extensive fractographic studies while evaluating the effects of material formulations, temperature, and loading rates on the loading response, tearing energy, induced damage, and tearing phenomena in SBR (Styrene Butadiene Rubber) containing different amounts of CB (Carbon Black) filler. We have also examined failures in tank track pads, as well as laboratory-tested samples cut from new track pads. In this paper we report on observations made during the actual stretching, tearing and failure of elastomeric samples pulled in tension at a constraint stroke-diplacement rate. 15 refs., 12 figs.

  1. Synchrotron X-ray Scattering; Sensile Strength and Strain-Induced Crystallization in Carbon Black Filled Natural Rubber

    SciTech Connect

    Toki,S.; Minouchi, N.; Sics, I.; Hsiao, B.; Kohjiya, S.

    2008-01-01

    The tensile strength of rubber depends on a combination of contributions, in particular on the finite extensibility of chain segments between network points and on strain-induced crystallization. In order to achieve high tensile strength at high strain at break, we optimized the composition and processing parameters to gain high molecular flexibility by the cure conditions, to acquire high flexibility of sulfur bridges by the accelerator, and to increase the modulus level without losing rubber molecule flexibility by carbon black. As a result, our formula performed a tensile strength of 42.5 MPa at 25 C under ISO-37, as officially measured by the Society of Rubber Industry, Japan, in 2004.

  2. Modified natural graphite as anode material for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Wu, Y. P.; Jiang, C.; Wan, C.; Holze, R.

    A concentrated nitric acid solution was used as an oxidant to modify the electrochemical performance of natural graphite as anode material for lithium ion batteries. Results of X-ray photoelectron spectroscopy, electron paramagnetic resonance, thermogravimmetry, differential thermal analysis, high resolution electron microscopy, and measurement of the reversible capacity suggest that the surface structure of natural graphite was changed, a fresh dense layer of oxides was formed. Some structural imperfections were removed, and the stability of the graphite structure increased. These changes impede decomposition of electrolyte solvent molecules, co-intercalation of solvated lithium ions and movement of graphene planes along the a-axis direction. Concomitantly, more micropores were introduced, and thus, lithium intercalation and deintercalation were favored and more sites were provided for lithium storage. Consequently, the reversible capacity and the cycling behavior of the modified natural graphite were much improved by the oxidation. Obviously, the liquid-solid oxidation is advantageous in controlling the uniformity of the products.

  3. Failure studies on rubber and rubber composites

    NASA Astrophysics Data System (ADS)

    Tao, Zhenghong

    A research study has been conducted to investigate selected failure processes in rubber and rubbery composites. Specific failure modes and materials considered included mechanical tearing of rubber-coated fabrics and mechanical/thermal fatigue of carbon black-filled elastomers. Experimental efforts developed novel evaluation techniques that were used to access failure resistance of the materials, as well as to elucidate molecular structure/physical properties relationships. Results are presented in multi-monograph format consisting of a series of four interdependent papers published in peer-reviewed journals. The first monograph measures the tear resistance of a series of polyester fabrics, of controlled fill-yarn size, coated with a compounded butyl rubber resin. A constrained trouser tear test is used to quantify the role of yarn mobility on crack-tip development and the resultant tear strength. As the area around a propagating crack is constrained, tear strength decreases by several orders of magnitude, indicating that the ability of the composite structure to dissipate energy away from the crack tip contributes more to tear resistance than the intrinsic strength of the concomitant materials. Monograph number two continues the work of the first by developing a novel cutting technique to monitor the role of the fiber/rubber interphase during tear propagation. This approach was applied to five different elastomers coated onto one of the polyester yarns. These data show a threefold increase in strength is possible by proper optimization of the fiber/rubber bond. In the third monograph, five different rubber bushing compounds were evaluated for mechanical/thermal fatigue resistance. Samples were dynamically excited in combined compression and shear loadings using a specially designed test fixture. Results indicated that heat build-up was a major contributing factor to the eventual failure of the materials via a complex fracture mechanism, with epoxidized natural

  4. Polymer blends made of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) and epoxidized natural rubber: Thermal and mechanical response

    NASA Astrophysics Data System (ADS)

    Salim, Yoga Sugama; Han, Chan Chin; Kammer, Hans-Werner; Kumar, Sudesh; Neon, Gan Seng

    2015-08-01

    The ever-increasing demand of biodegradable over conventional polymers places microbial polyhydroxyalkanoates (PHA) as an ideal choice of research material for specific applications. In this study, polymer blends made of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx) and epoxidized natural rubber (ENR) were prepared using solution casting technique. The influence of ENR on thermal, morphological and mechanical properties of P(3HB-co-3HHx) was investigated. There are two glass transition (Tg) temperatures observed using differential scanning calorimeter. This indicates that P(3HB-co-3HHx) and ENR are immiscible at macroscopic level. Although the Tg of P(3HB-co-3HHx) is seen to shift toward ENR in the least manner, infrared analysis suggests that the crystal structure of P(3HB-co-3HHx) retains its conformational structure. In terms of morphology, ENR exists as droplets in P(3HB-co-3HHx)-rich phase, e.g. at ENR weight fraction (wENR) of 0.3. In dynamic mechanical analysis, all blend compositions exhibit solid-like behavior, with storage moduli larger than loss moduli, across the frequency sweep at room temperature.

  5. Tailoring percolating conductive networks of natural rubber composites for flexible strain sensors via a cellulose nanocrystal templated assembly.

    PubMed

    Wang, Shuman; Zhang, Xinxing; Wu, Xiaodong; Lu, Canhui

    2016-01-21

    Conductive polymer composites (CPCs) just above the percolation threshold exhibit a unique strain-reversible electric response upon application of tensile strain, which can be used to prepare strain sensors. However, it is difficult to balance the electric conductivity which is fundamental to a stable output signal and the strain sensing sensitivity due to the relatively dense conductive pathways of the traditional CPCs. Constructing a "brittle" but effective conductive network structure in CPCs is the essential foundation of a desirable sensing material. Here, we demonstrate for the first time that highly flexible, stretchable, sensitive, and reversible strain sensors can be fabricated by a facile latex assembly approach, in which nontoxic, sustainable and biodegradable cellulose nanocrystals played a key role in tailoring the percolating network of conductive natural rubber (NR)/carbon nanotube (CNT) composites. The resulting nanocomposites with a continuous 3D conductive structure exhibited a very low electrical conductivity percolation threshold (4-fold lower than that of the conventional NR/CNT composites), high resistivity and sensitivity (gauge factor ≈ 43.5) and meanwhile good reproducibility of up to 100% strain. The proposed materials and principles in this study open up a novel practical approach to design high performance flexible sensors for a broad range of multifunctional applications. PMID:26542376

  6. Reinforcement of natural rubber hybrid composites based on marble sludge/Silica and marble sludge/rice husk derived silica

    PubMed Central

    Ahmed, Khalil; Nizami, Shaikh Sirajuddin; Riza, Nudrat Zahid

    2013-01-01

    A research has been carried out to develop natural rubber (NR) hybrid composites reinforced with marble sludge (MS)/Silica and MS/rice husk derived silica (RHS). The primary aim of this development is to scrutinize the cure characteristics, mechanical and swelling properties of such hybrid composite. The use of both industrial and agricultural waste such as marble sludge and rice husk derived silica has the primary advantage of being eco-friendly, low cost and easily available as compared to other expensive fillers. The results from this study showed that the performance of NR hybrid composites with MS/Silica and MS/RHS as fillers is extremely better in mechanical and swelling properties as compared with the case where MS used as single filler. The study suggests that the use of recently developed silica and marble sludge as industrial and agricultural waste is accomplished to provide a probable cost effective, industrially prospective, and attractive replacement to the in general purpose used fillers like china clay, calcium carbonate, and talc. PMID:25685484

  7. Quantification of the effects of crumb rubber in CRM binders

    NASA Astrophysics Data System (ADS)

    Putman, Bradley James

    Since the mid-1960s, crumb rubber has been used to modify asphalt binders. The crumb rubber, also referred to as crumb rubber modifier (CRM), is produced by grinding scrap tires into fine powders with particulate sizes generally smaller than 2 mm. In most cases, CRM is incorporated into binder using the "wet" method, where the crumb rubber is blended with the asphalt binder. The binder modification that occurs during this blending process is physical in nature, where the lighter oils of the binder diffuse into the CRM particles. As the rubber particles absorb the oils, the particles swell; therefore, increasing the viscosity and stiffness of the CRM binder. This research evaluated the viscosity and complex shear modulus (G*) of 36 different laboratory-produced CRM binder combinations (two CRM processing methods, two CRM contents, three CRM sizes, and three binder sources) and three base binders. From this investigation, a method was developed to quantify the effects of the crumb rubber modification. These effects were identified as the interaction effect (IE) resulting from the diffusion of the lighter binder factions into the rubber particles and the particle effect (PE), which is the result of the change in the rheological properties due to the filling effect of the particulate CRM. Following statistical analyses of the results, it was determined that CRM binders had greater viscosity and complex shear modulus (G*) values than the base binders. These values increased with CRM content. The CRMs having higher surface area (i.e., ambient ground and finer CRM) generally had higher IE values, while the PE generally increased with particle size. HP-GPC testing indicated that the CRM binders also had higher large molecular size (LMS) fractions and lower small molecular size (SMS) fractions as determined from the HP-GPC profiles. As the LMS increased and the SMS decreased, the IE increased. Two of the three binder sources followed this trend, indicating that those

  8. Effects of Core-Shell Rubber (CSR) Nanoparticles on the Cryogenic Fracture Toughness of CSR Modified Epoxy

    NASA Technical Reports Server (NTRS)

    Wang, Jun; Magee, Daniel; Schneider, Judy; Cannon, Seth

    2009-01-01

    This study investigated the effects of core-shell rubber (CSR) nanoparticles on the mechanical properties and fracture toughness of an epoxy resin at ambient and liquid nitrogen (LN2) temperatures. Varying amounts of Kane Ace(Registered TradeMark) MX130 and Kane Ace(Registered TradeMark) MX960 toughening agent were added to a commercially available EPON 862/Epikure W epoxy resin. Elastic modulus was calculated using quasi-static tensile data. Fracture toughness was evaluated by the resulting breaking energy measured in Charpy impact tests conducted on an instrumented drop tower. The size and distribution of the CSR nanoparticles were characterized using Transmission Electron Microscopy (TEM) and Small Angle X-ray Scattering (SAXS). Scanning Electron Microscopy (SEM) was used to study the fracture surface morphology. The addition of the CSR nanoparticles increased the breaking energy with negligible change in elastic modulus and ultimate tensile stress (UTS). At ambient temperature the breaking energy increased with increasing additions of the CSR nanoparticles up to 13.8wt%, while at LN2 temperatures, it reached a plateau at much lower CSR concentration.

  9. The functional analyses of the cis-prenyltransferase and the rubber elongation factor in rubber biosynthesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber (cis-1,4-polyisoprene) is an essential plant derived commodity required for the manufacture of numerous industrial, medical and household items. Rubber is synthesized and sequestered on cytsolic vesicles known as rubber particles. When provided with farnesyl pyrophosphate (FPP) and is...

  10. Modified natural nanoparticles as contrast agents for medical imaging

    PubMed Central

    Cormode, David P.; Jarzyna, Peter A.; Mulder, Willem J. M.; Fayad, Zahi A.

    2009-01-01

    The development of novel and effective contrast agents is one of the drivers of the ongoing improvement in medical imaging. Many of the new agents reported are nanoparticle-based. There are a variety of natural nanoparticles known, e.g. lipoproteins, viruses or ferritin. Natural nanoparticles have advantages as delivery platforms such as biodegradability. In addition, our understanding of natural nanoparticles is quite advanced, allowing their adaptation as contrast agents. They can be labeled with small molecules or ions such as Gd3+ to act as contrast agents for magnetic resonance imaging, 18F to act as positron emission tomography contrast agents or fluorophores to act as contrast agents for fluorescence techniques. Additionally, inorganic nanoparticles such as iron oxide, gold nanoparticles or quantum dots can be incorporated to add further contrast functionality. Furthermore, these natural nanoparticle contrast agents can be rerouted from their natural targets via the attachment of targeting molecules. In this review, we discuss the various modified natural nanoparticles that have been exploited as contrast agents. PMID:19900496

  11. Additive CHARMM force field for naturally occurring modified ribonucleotides.

    PubMed

    Xu, You; Vanommeslaeghe, Kenno; Aleksandrov, Alexey; MacKerell, Alexander D; Nilsson, Lennart

    2016-04-15

    More than 100 naturally occurring modified nucleotides have been found in RNA molecules, in particular in tRNAs. We have determined molecular mechanics force field parameters compatible with the CHARMM36 all-atom additive force field for all these modifications using the CHARMM force field parametrization strategy. Emphasis was placed on fine tuning of the partial atomic charges and torsion angle parameters. Quantum mechanics calculations on model compounds provided the initial set of target data, and extensive molecular dynamics simulations of nucleotides and oligonucleotides in aqueous solutions were used for further refinement against experimental data. The presented parameters will allow for computational studies of a wide range of RNAs containing modified nucleotides, including the ribosome and transfer RNAs. PMID:26841080

  12. Additive CHARMM force field for naturally occurring modified ribonucleotides

    PubMed Central

    Xu, You; Vanommeslaeghe, Kenno; Aleksandrov, Alexey; MacKerell, Alexander D.

    2016-01-01

    More than 100 naturally occurring modified nucleotides have been found in RNA molecules, in particular in tRNAs. We have determined molecular mechanics force field parameters compatible with the CHARMM36 all‐atom additive force field for all these modifications using the CHARMM force field parametrization strategy. Emphasis was placed on fine tuning of the partial atomic charges and torsion angle parameters. Quantum mechanics calculations on model compounds provided the initial set of target data, and extensive molecular dynamics simulations of nucleotides and oligonucleotides in aqueous solutions were used for further refinement against experimental data. The presented parameters will allow for computational studies of a wide range of RNAs containing modified nucleotides, including the ribosome and transfer RNAs. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc. PMID:26841080

  13. Adhesion of nitrile rubber to UV-assisted surface chemical modified PET fabric, part II: Interfacial characterization of MDI grafted PET

    NASA Astrophysics Data System (ADS)

    Razavizadeh, Mahmoud; Jamshidi, Masoud

    2016-08-01

    Fiber to rubber adhesion is an important subject in rubber industry. It is well known that surface treatment (i.e. physical, mechanical and chemical) is an effective method to improve interfacial bonding of fibers and/or fabrics to rubbers. UV irradiation is an effective method which has been used to increase fabric-rubber interfacial interactions. In this research UV assisted chemical modification of PET fabrics was used to increase PET to nitrile rubber (NBR) adhesion. Nitrile rubber is a perfect selection as fuel and oil resistant rubber. However it has weak bonding to PET fabric. For this purpose PET fabric was carboxylated under UV irradiation and then methylenediphenyl diisocyanate (MDI) was grafted on carboxylated PET. The chemical composition of the fabric before and after surface treatment was investigated by X-ray photoelectron spectroscopy (XPS). The sectional morphology of the experimental PET fibers and the interface between rubber compound and PET fabric was studied using scanning electron microscope (SEM). The morphology and structure of the product were analyzed by an energy dispersive X-ray spectrometer (EDX). FTIR-ATR and H NMR analysis were used to assess surface modifications on the PET irradiated fabrics.

  14. MAGNESIUM ION REGULATION OF THE IN VITRO RUBBER BIOSYNTHESIS BY PARTHENIUM ARGENTATUM GRAY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber is produced by a rubber transferase (a cis-preny transferase). Rubber transferase uses allylic pyrophosphate to initiate the rubber molecule and isopentenyl pyrophosphate (IPP) to form the polymer. Rubber biosynthesis also requires a divalent metal cation. Understanding how molecular ...

  15. Initiator-independent and initiator-dependent rubber biosynthesis in Ficus elastica.

    PubMed

    Espy, Stephanie C; Keasling, Jay D; Castillón, Javier; Cornish, Katrina

    2006-04-15

    The rubber-producing tree, Ficus elastica (the Indian rubber tree), requires the same substrates for rubber production as other rubber-producing plants, such as Hevea brasiliensis (the Brazilian or Para rubber tree), the major source of commercial natural rubber in the world, and Parthenium argentatum (guayule), a widely studied alternative for natural rubber production currently under commercial development. Rubber biosynthesis can be studied, in vitro, using purified, enzymatically active rubber particles, an initiator such as FPP, IPP as the source of monomer, and a metal cofactor such as Mg2+. However, unlike H. brasiliensis and P. argentatum, we show that enzymatically active rubber particles purified from F. elastica are able to synthesize rubber, in vitro, in the absence of added initiator. In this paper, we characterize, for the first time, the kinetic differences between initiator-dependent rubber biosynthesis, and initiator-independent rubber biosynthesis, and the effect of cofactor concentration on both of these processes. PMID:16488387

  16. Cellulose: A review as natural, modified and activated carbon adsorbent.

    PubMed

    Suhas; Gupta, V K; Carrott, P J M; Singh, Randhir; Chaudhary, Monika; Kushwaha, Sarita

    2016-09-01

    Cellulose is a biodegradable, renewable, non-meltable polymer which is insoluble in most solvents due to hydrogen bonding and crystallinity. Natural cellulose shows lower adsorption capacity as compared to modified cellulose and its capacity can be enhanced by modification usually by chemicals. This review focuses on the utilization of cellulose as an adsorbent in natural/modified form or as a precursor for activated carbon (AC) for adsorbing substances from water. The literature revealed that cellulose can be a promising precursor for production of activated carbon with appreciable surface area (∼1300m(2)g(-1)) and total pore volume (∼0.6cm(3)g(-1)) and the surface area and pore volume varies with the cellulose content. Finally, the purpose of review is to report a few controversies and unresolved questions concerning the preparation/properties of ACs from cellulose and to make aware to readers that there is still considerable scope for future development, characterization and utilization of ACs from cellulose. PMID:27265088

  17. Synthesis of tetraaza bromide macrocyclic and studies of its effect on poly(methyl methacrylate) grafted natural rubber (MG49) - lithium tertrafluoroborate (LiBF{sub 4}) films

    SciTech Connect

    Mariam, Siti Nor; Yamin, Bohari M.; Ahmad, Azizan

    2013-11-27

    Good Poly(Methyl Methacrylate) Grafted natural Rubber (MG49) films with homogeneous and smooth surface were obtained in the presence of Lithium Tertrafluoroborate (LiBF{sub 4}) and 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7,14-dienium bromide, (Me{sub 6}N{sub 4}H{sub 4})Br{sub 2} as dopants. The conductivity was found to be 3.63×10{sup −6} S/cm an increase by seven fold compare to the undoped MG49.

  18. Synthesis of tetraaza bromide macrocyclic and studies of its effect on poly(methyl methacrylate) grafted natural rubber (MG49) - lithium tertrafluoroborate (LiBF4) films

    NASA Astrophysics Data System (ADS)

    Mariam, Siti Nor; Yamin, Bohari M.; Ahmad, Azizan

    2013-11-01

    Good Poly(Methyl Methacrylate) Grafted natural Rubber (MG49) films with homogeneous and smooth surface were obtained in the presence of Lithium Tertrafluoroborate (LiBF4) and 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7,14-dienium bromide, (Me6N4H4)Br2 as dopants. The conductivity was found to be 3.63×10-6 S/cm an increase by seven fold compare to the undoped MG49.

  19. Wear of steel by rubber

    NASA Technical Reports Server (NTRS)

    Gent, A. N.; Pulford, C. T. R.

    1978-01-01

    Wear of a steel blade used as a scraper to abrade rubber surfaces has been found to take place much more rapidly on a cis-polyisoprene (natural rubber) surface than on a cis-polybutadiene surface, and much more rapidly in an inert atmosphere than in air. These observations are attributed to the direct attack upon steel of free-radical species generated by mechanical rupture of elastomer molecules during abrasion.

  20. The rationale for transforming sunflower into a rubber-producing crop

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber is an irreplaceable raw material and constitutes about 45% of the total amount of both natural and synthetic rubber used. Currently, nearly all commercial natural rubber comes from a single species, the Brazilian rubber tree (Hevea brasiliensis) and the United States is almost complet...

  1. Adsorption of dissolved natural organic matter by modified activated carbons.

    PubMed

    Cheng, Wei; Dastgheib, Seyed A; Karanfil, Tanju

    2005-06-01

    Adsorption of dissolved natural organic matter (DOM) by virgin and modified granular activated carbons (GACs) was studied. DOM samples were obtained from two water treatment plants before (i.e., raw water) and after coagulation/flocculation/sedimentation processes (i.e., treated water). A granular activated carbon (GAC) was modified by high temperature helium or ammonia treatment, or iron impregnation followed by high temperature ammonia treatment. Two activated carbon fibers (ACFs) were also used, with no modification, to examine the effect of carbon porosity on DOM adsorption. Size exclusion chromatography (SEC) and specific ultraviolet absorbance (SUVA(254)) were employed to characterize the DOMs before and after adsorption. Iron-impregnated (HDFe) and ammonia-treated (HDN) activated carbons showed significantly higher DOM uptakes than the virgin GAC. The enhanced DOM uptake by HDFe was due to the presence of iron species on the carbon surface. The higher uptake of HDN was attributed to the enlarged carbon pores and basic surface created during ammonia treatment. The SEC and SUVA(254) results showed no specific selectivity in the removal of different DOM components as a result of carbon modification. The removal of DOM from both raw and treated waters was negligible by ACF10, having 96% of its surface area in pores smaller than 1 nm. Small molecular weight (MW) DOM components were preferentially removed by ACF20H, having 33% of its surface area in 1--3 nm pores. DOM components with MWs larger than 1600, 2000, and 2700 Da of Charleston raw, Charleston-treated, and Spartanburg-treated waters, respectively, were excluded from the pores of ACF20H. In contrast to carbon fibers, DOM components from entire MW range were removed from waters by virgin and modified GACs. PMID:15927230

  2. Treatment of natural rubber processing wastewater using a combination system of a two-stage up-flow anaerobic sludge blanket and down-flow hanging sponge system.

    PubMed

    Tanikawa, D; Syutsubo, K; Hatamoto, M; Fukuda, M; Takahashi, M; Choeisai, P K; Yamaguchi, T

    2016-01-01

    A pilot-scale experiment of natural rubber processing wastewater treatment was conducted using a combination system consisting of a two-stage up-flow anaerobic sludge blanket (UASB) and a down-flow hanging sponge (DHS) reactor for more than 10 months. The system achieved a chemical oxygen demand (COD) removal efficiency of 95.7% ± 1.3% at an organic loading rate of 0.8 kg COD/(m(3).d). Bacterial activity measurement of retained sludge from the UASB showed that sulfate-reducing bacteria (SRB), especially hydrogen-utilizing SRB, possessed high activity compared with methane-producing bacteria (MPB). Conversely, the acetate-utilizing activity of MPB was superior to SRB in the second stage of the reactor. The two-stage UASB-DHS system can reduce power consumption by 95% and excess sludge by 98%. In addition, it is possible to prevent emissions of greenhouse gases (GHG), such as methane, using this system. Furthermore, recovered methane from the two-stage UASB can completely cover the electricity needs for the operation of the two-stage UASB-DHS system, accounting for approximately 15% of the electricity used in the natural rubber manufacturing process. PMID:27120630

  3. The enzymatic synthesis of rubber polymer

    SciTech Connect

    Venkatachalam, K.V.; Wooten, L.; Benedict, C.R. )

    1990-05-01

    Washed rubber particles (WRP) isolated from stem homogenates of Parthenium argentatum by ultracentrifugation and gel filtration on columns of LKB Ultrogel AcA34 contain a tightly bound rubber transferase which catalyzes the polymerization of IPP into rubber polymer. The polymerization reaction requires Mg{sup 2+}, IPP and an allylic-PP. The Km values for Mg{sup 2+}, IPP and DMAPP are 5.2{times}10{sup {minus}4}M, 8.3{times}10{sup {minus}5} M and 9.6{times}10{sup {minus}5}M respectively. Gel permeation chromatography of the enzymatic polymer product on 3 linear columns of 1{times}10{sup 6} to 500 {angstrom} Ultrastyragel shows that the in vitro formed polymer has a similar mol wt to natural rubber. Over 90% of the in vitro formation of the rubber polymer was a de novo polymerization reaction from DMAPP initiator and IPP monomers. The bound rubber polymerase substantially differs from cytosolic rubber transferase which catalyzes only chain lengthening reactions. Treatment of the WRP with Chaps solubilized the bound rubber transferase which was further purified by DEAE-cellulose chromatography. The purified preparation primarily consists of a 52 kD polypeptide which binds to a photolabile substrate analog. The soluble rubber transferase catalyzes the synthesis of a 1{times}10{sup 5} mol wt rubber polymer from Mg{sup 2+}, DMAPP, IPP and detergent.

  4. Combination biological and microwave treatments of used rubber products

    DOEpatents

    Fliermans, Carl B.; Wicks, George G.

    2002-01-01

    A process and resulting product is provided in which a vulcanized solid particulate, such as vulcanized crumb rubber, has select chemical bonds altered by biotreatment with thermophillic microorganisms selected from natural isolates from hot sulfur springs. Following the biotreatment, microwave radiation is used to further treat the surface and to treat the bulk interior of the crumb rubber. The resulting combined treatments render the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger loading levels and sizes of the treated crumb rubber can be used in new rubber mixtures and good properties obtained from the new recycled products.

  5. Bird communities of natural and modified habitats in Panama

    USGS Publications Warehouse

    Petit, L.J.; Petit, D.R.; Christian, D.G.; Powell, H.D.W.

    1999-01-01

    Only a small proportion of land can realistically be protected as nature reserves and thus conservation efforts also must focus on the ecological value of agroecosystems and developed areas surrounding nature reserves. In this study, avian communities were surveyed in 11 habitat types in central Panama, across a gradient from extensive forest to intensive agricultural land uses, to examine patterns of species richness and abundance and community composition. Wooded habitats, including extensive and fragmented forests, shade coffee plantations, and residential areas supported the most species and individuals. Nearctic-Neotropical migratory species were most numerous in lowland forest fragments, shade coffee, and residential areas. Introduced Pinus caribbea and sugar cane plantations supported the fewest species compared to all other habitats. Cattle pastures left fallow for less than two years supported more than twice as many total species as actively grazed pastures, such that species richness in fallow pastures was similar to that found in wooded habitats. Community similarities were relatively low among all habitat types (none exceeding the observed 65% similarity between extensive and fragmented lowland forests), but communities in shade coffee and residential areas were 43% and 54% similar to lowland forest fragments, respectively. Fallow pastures and residential areas shared 60% of their species. Bird communities in shade coffee and residential areas were characterized by higher proportions of frugivorous and nectarivorous species than in native forests. These same guilds also were better represented in fallow than in grazed pastures. Raptors and piscivorous species were most prevalent in cattle pastures and rice fields. These results, though based upon only species richness and abundance, demonstrate that many human-altered habitats have potential ecological value for birds, and conservation efforts in tropical areas should focus greater attention on

  6. Great advantages in using a natural rubber instead of a synthetic SBR in a pro-oxidant system for degradable LDPE.

    PubMed

    Khabbaz, F; Albertsson, A C

    2000-01-01

    Different pro-oxidant systems are used in degradable low-density polyethylene (LDPE). The main question is the degradation products and not the degradation time from the used materials. The pro-oxidant formulation used consisted of manganese stearate and natural rubber (NR) or manganese stearate and a synthetic, styrene-butadiene copolymer rubber (SBR). The samples were heated in air at 100 degrees C in sealed glass vials. The molecular weight changes were measured by size exclusion chromatography (SEC). The volatile and nonvolatile degradation products have been identified by gas chromatography-mass spectrometry (GC/MS). A wide variety of degradation products were identified, including ketones, carboxylic acids, keto acids, dicarboxylic acids, and furanones as a homologous series. Benzaldehyde, acetophenone, benzoic acid, benzyl benzoate, and two benzene derivative compounds were identified only in the LDPE-SBR system. These aromatic compounds originate from the styrene part of SBR. The advantages using pro-oxidant containing NR are more effective degradation of LDPE without any aromatic degradation products. PMID:11710197

  7. Supertoughened Biobased Poly(lactic acid)-Epoxidized Natural Rubber Thermoplastic Vulcanizates: Fabrication, Co-continuous Phase Structure, Interfacial in Situ Compatibilization, and Toughening Mechanism.

    PubMed

    Wang, Youhong; Chen, Kunling; Xu, Chuanhui; Chen, Yukun

    2015-09-10

    In the presence of dicumyl peroxide (DCP), biobased thermoplastic vulcanizates (TPVs) composed of poly(lactic acid) (PLA) and epoxidized natural rubber (ENR) were prepared through dynamic vulcanization. Interfacial in situ compatibilization between PLA and ENR phases was confirmed by Fourier transform infrared spectroscopy (FT-IR). A novel "sea-sea" co-continuous phase in the PLA/ENR TPVs was observed through scanning electron microscopy (SEM) and differed from the typical "sea-island" morphology that cross-linked rubber particles dispersed in plastic matrix. A sharp, brittle-ductile transition occurred with 40 wt % of ENR, showing a significantly improved impact strength of 47 kJ/m(2), nearly 15 times that of the neat PLA and 2.6 times that of the simple blend with the same PLA/ENR ratio. Gel permeation chromatography (GPC) and dynamic mechanical analysis (DMA) results suggested that a certain amount of DCP was consumed in the PLA phase, causing a slight cross-linking or branching of PLA molecules. the effects of various DCP contents on the impact property were investigated. The toughening mechanism under impact testing was researched, and the influence factors for toughening were discussed. PMID:26301924

  8. Biofilm control with natural and genetically-modified phages.

    PubMed

    Motlagh, Amir Mohaghegh; Bhattacharjee, Ananda Shankar; Goel, Ramesh

    2016-04-01

    Bacteriophages, as the most dominant and diverse entities in the universe, have the potential to be one of the most promising therapeutic agents. The emergence of multidrug-resistant bacteria and the antibiotic crisis in the last few decades have resulted in a renewed interest in phage therapy. Furthermore, bacteriophages, with the capacity to rapidly infect and overcome bacterial resistance, have demonstrated a sustainable approach against bacterial pathogens-particularly in biofilm. Biofilm, as complex microbial communities located at interphases embedded in a matrix of bacterial extracellular polysaccharide substances (EPS), is involved in health issues such as infections associated with the use of biomaterials and chronic infections by multidrug resistant bacteria, as well as industrial issues such as biofilm formation on stainless steel surfaces in food industry and membrane biofouling in water and wastewater treatment processes. In this paper, the most recent studies on the potential of phage therapy using natural and genetically-modified lytic phages and their associated enzymes in fighting biofilm development in various fields including engineering, industry, and medical applications are reviewed. Phage-mediated prevention approaches as an indirect phage therapy strategy are also explored in this review. In addition, the limitations of these approaches and suggestions to overcome these constraints are discussed to enhance the efficiency of phage therapy process. Finally, future perspectives and directions for further research towards a better understanding of phage therapy to control biofilm are recommended. PMID:26931607

  9. Burning rubber

    SciTech Connect

    Not Available

    1987-09-01

    Mario Andretti, look out You are about to be surpassed in the burning rubber category by a joint venture between Oxford Energy Company and General Electric. The two companies are building the first whole tire-to-energy facility in the US in Modesto, California. This $41 million facility does not require tires to be shredded prior to incineration; it has the capacity to burn 700 tires per minute. The electricity generated will be provided to a utility company. Oxford says there are two billion waste tires on the ground and this number is increasing by 220 million a year. Of that amount, only 18 million a year are recycled.

  10. Biotechnological Development of Domestic Rubber Producing Crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber is an irreplaceable raw material vital to industry, transportation, medicine and defense, largely produced from clonal plantations of Hevea brasiliensis in South-east Asia. Additional rubber-producing crops are greatly desired to increase biodiversity, protect supplies, and provide a...

  11. Nature of the chemical reaction for furfural modified asphalt

    SciTech Connect

    Memon, G.M.; Chollar, B.H.

    1994-12-31

    Three of the most serious problems of asphalt pavements today are rutting, cracking, and susceptibility to moisture damage (stripping). Asphalt manufacturers have been mixing asphalts with polymers to produce polymer-modified asphalts with improved rheological properties. However, the costs for these improved polymer-modified asphalts are almost double that of regular asphalts. FHWA researchers have found that asphalt modified by the chemical, furfural (which is prepared by simple elimination reaction of aldopentoses obtained from oat hulls), exhibited better stripping properties and was less temperature susceptible than the virgin asphalt while costing less than polymer-modified asphalts. This paper discusses the possible structure of the furfural-modified asphalt, data for the virgin and furfural-modified asphalts and their Corbett fractions, data from a model reaction between phenol and furfural, and a possible explanation of this structure based on these data.

  12. Encapsulation of piceatannol, a naturally occurring hydroxylated analogue of resveratrol, by natural and modified cyclodextrins.

    PubMed

    Matencio, Adrián; García-Carmona, Francisco; López-Nicolás, José Manuel

    2016-05-18

    In this work, an in-depth study of the interaction between piceatannol (a type of stilbene with high biological activity) and different natural and modified cyclodextrins (CDs) is made, using steady state fluorescence. This bioactive molecule forms a 1 : 1 complex with all the natural (α-CD, β-CD and γ-CD) and modified (HP-β-CD, HE-β-CD and M-β-CD) CDs tested. Among natural CDs, the interaction of piceatannol with β-CD was the most efficient. However, the modified CDs showed higher encapsulation constants (KF) than β-CD, except M-β-CD; the highest KF being found for HP-β-CD (14 048 ± 702 M(-1)). The encapsulation of piceatannol in the internal cavity of CDs showed a strong dependence on pH and temperature. The interaction between HP-β-CD and piceatannol was less effective in the pH region where the stilbene begins to suffer the deprotonation of its hydroxyl group. Moreover, the values of KF decreased as the system temperature increased. To obtain information on the mechanism involved in the piceatannol affinity for CD, the thermodynamic parameters of the complexation (ΔH°, ΔS° and ΔG°) were studied, the results showed a negative entropy (-3.7 ± 0.2 J mol(-1) K(-1)), enthalpy (-24.6 ± 1.2 kJ mol(-1)) and Gibbs free energy change at 25 °C (-23.5 ± 1.2 J mol(-1)). Finally, molecular docking calculations provided further insights into how the different interactions influence the complexation constant. A high degree of correlation was observed between the computed scores and experimental values. PMID:27142512

  13. A sustainability review of domestic rubber from the guayule plant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guayule (Parthenium argentatum Gray) is an arid-adapted, low-input perennial shrub native to Mexico and southern Texas that has received considerable attention as an alternative source of natural rubber. It has potential to replace the most common types of rubbers, including synthetic rubber derived...

  14. Large-scale orientation in a vulcanized stretched natural rubber network: proved by in situ synchrotron X-ray diffraction characterization.

    PubMed

    Weng, Gengsheng; Huang, Guangsu; Qu, Liangliang; Nie, Yijing; Wu, Jinrong

    2010-06-01

    In situ studies of strain-induced crystallization in unfilled and multiwalled carbon nanotube (MWCNT)-filled natural rubber (NR) were carried out by using synchrotron wide-angle X-ray diffraction (WAXD). Synchrotron WAXD results indicate that more nuclei appear in the MWCNT-filled NR sample, leading to higher crystallinity, lower onset strain of crystallization, and remarkable enhancement in tensile strength. During deformation, despite the amorphous chains remaining in isotropic orientation, the domains of larger scale (10-100 nm) with high network chain density in the NR matrix are oriented. The MWCNTs induce significant variation of this orientational process, and it is monitored by the stearic acid (SA) crystallites, which are effective nanoprobes of the amorphous phase. The results indicate that a small amount of MWCNTs and SA crystallites can be used as new tools to analyze the microstructural orientation of NR during deformation. The results also yield new insight into the strain-induced crystallization mechanism. PMID:20455577

  15. Comparison of epoxidised natural rubber (enr) 37.5 and enr 25/ enr 50 physical blend: Specialty polymer for 'green tyre' application

    NASA Astrophysics Data System (ADS)

    Wan, N. Y.; Chin, K. P.; Saad, C. S. Mt

    2010-05-01

    A comparison study of new grade epoxidised natural rubber (ENR) containing 37.5 mole % epoxidation (ENR 37.5) with ENR 25/ ENR 50 blend, prepared by physical blending of ENR 25 with ENR 50, was done using truck tyre formulation. The ENR 25 / ENR 50 physical blend exhibited certain similar physical properties to ENR 37.5 even though Dynamic Mechanical Thermal Analyser (DMTA) analysis showed two glass transition temperatures (Tg) in the ENR 25/ ENR 50 vulcanisate. ENR 37.5 and ENR 25 / ENR 50 blend vulcanizates exhibited similar DMTA tan delta (tan Δ) curves at 0°C and 60°C, indicating potentially comparable wet grip and rolling resistance in 'green tyre' tread. Moreover, the heat build-up property for both vulcanizates is low, which is advantageous for tyre application.

  16. Rotating-frame spin-lattice relaxation time imaging by radio-frequency field gradients: visualization of strained crosslinked natural rubbers

    NASA Astrophysics Data System (ADS)

    Chaumette, H.; Grandclaude, D.; Canet, D.

    2003-08-01

    NMR imaging by radio-frequency field gradients ( B1 gradients) is especially convenient for heterogeneous samples and/or in the case of relatively short transverse relaxation times. The method has been combined with the application of two spin-lock periods of different duration so as to produce rotating-frame spin-lattice relaxation time ( T1 ρ) images. In the case of natural rubber samples with different crosslink densities, such images are not only characteristic of the crosslink density but also reveal the way in which the material has been stressed. The strained parts can be visualized either directly or through histograms showing the T1 ρ distribution over the whole sample.

  17. Role of Stearic Acid in the Strain-Induced Crystallization of Crosslinked Natural Rubber and Synthetic Cis-1,4-Polyisoprene

    SciTech Connect

    Kohjiya,S.; Tosaka, M.; Furutani, M.; Ikeda, Y.; Toki, S.; Hsiao, B.

    2007-01-01

    Strain-induced crystallization of crosslinked natural rubber (NR) and its synthetic analogue, cis-1,4-polyisoprene (IR), both mixed with various amounts of stearic acid (SA), were investigated by time-resolved X-ray diffraction using a powerful synchrotron radiation source and simultaneous mechanical (tensile) measurement. No acceleration or retardation was observed on NR in spite of the increase of SA amount. Even the SA-free IR crystallized upon stretching, and the overall crystallization behavior of IR shifted to the larger strain ratio with increasing SA content. No difference due to the SA was detected in the deformation of crystal lattice by stress for both NR and IR. These results suggested that the extended network chains are effective for the initiation of crystallization upon stretching, while the role of SA is trivial. These behaviors are much different from their crystallization at low temperature by standing, where SA acts as a nucleating agent.

  18. Stress-induced melting of crystals in natural rubber: a new way to tailor the transition temperature of shape memory polymers.

    PubMed

    Heuwers, Benjamin; Quitmann, Dominik; Katzenberg, Frank; Tiller, Joerg C

    2012-09-26

    Lightly cross-linked natural rubber (NR, cis-1,4-polyisoprene) was found to be an exceptional cold programmable shape memory polymer (SMP) with strain storage of up to 1000%. These networks are stabilized by strain-induced crystals. Here, we explore the influence of mechanical stress applied perpendicular to the elongation direction of the network on the stability of these crystals. We found that the material recovers its original shape at a critical transverse stress. It could be shown that this is due to a disruption of the strain-stabilizing crystals, which represents a completely new trigger for SMPs. The variation of transverse stress allows tuning of the trigger temperature T(trig) (σ) in a range of 45 to 0 °C, which is the first example of manipulating the transition of a crystal-stabilized SMP after programming. PMID:22760997

  19. The role of the small rubber particle protein in determining rubber yields and polymer length in Russian dandelion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several proteins have been identified and implicated in natural rubber biosynthesis, one of which, the small rubber particle protein (SRPP), was originally identified in Hevea brasiliensis as an abundant protein associated with cytosolic vesicles known as rubber particles. While previous in vitro s...

  20. Improved methods for extraction and quantification of resin and rubber from guayule

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guayule, a desert shrub native to the Chihuahuan desert, is a natural source of high quality, hypo-allergenic rubber. Unlike rubber trees that produce rubber in lactifers, the rubber in guayule is produced in parenchyma cells of the bark tissue of stems and roots. Consequently, guayule tissue must...

  1. Anaerobic desulfurization of ground rubber with the thermophilic archaeon Pyrococcus furiosus--a new method for rubber recycling.

    PubMed

    Bredberg, K; Persson, J; Christiansson, M; Stenberg, B; Holst, O

    2001-01-01

    The anaerobic sulfur-reducing archaeon Pyrococcus furiosus was investigated regarding its capacity to desulfurize rubber material. The microorganism's sensitivity towards common rubber elastomers and additives was tested and several were shown to be toxic to P. furiosus. The microorganism was shown to utilize sulfur in vulcanized natural rubber and an increase in cell density was obtained when cultivated in the presence of spent tire rubber. Ethanol-leached cryo-ground tire rubber treated with P. furiosus for 10 days was vulcanized together with virgin rubber material (15% w/w) and the mechanical properties of the resulting material were determined. The increase in the stress at break value and the decrease in swell ratio and stress relaxation rate obtained for material containing microbially treated rubber (compared to untreated material) show the positive effects of microbial desulfurization on rubber. PMID:11234957

  2. Applicability of Landsat TM data for inventorying and monitoring of rubber (Hevea brasiliensis) plantations in Selangor, Malaysia: Linkages to policies

    NASA Astrophysics Data System (ADS)

    Suratman, Mohd Nazip

    2003-06-01

    Rubber tree (Hevea brasiliensis (Wild ex Adr. De Juss) Muell Arg.) plantations in Malaysia are important sources of natural rubber and wood products. Effective management and appropriate policy for these resources require reliable information on resource dynamics and forecasts of resource availability. The need for inventories and monitoring systems prompted this research into utilising ground information and satellite imagery for developing methods for forest plantation inventory. Monitoring procedures were developed using three dates of Landsat Thematic Mapper (TM) imagery. The specific objectives of the research were: (1) to develop an effective method for inventorying rubber tree plantations using an appropriate combination of satellite imagery and ground sampling in the State of Selangor, Malaysia; (2) to demonstrate the application of a Landsat TM-based rubber volume model in an extended area of rubber plantations south of Kuala Lumpur (KL), Malaysia; (3) to develop an operational methodology for monitoring land use/cover change, with a primary focus on rubber plantations; and (4) to identify relationships between the primary drivers of resource change and policies, and examine the evidence of policies---rubber area change linkages in the study area. Reasonably accurate predictions of the volume, age, and area of rubber plantations were obtained from Landsat TM data. The use of supervised image classification and an image segmentation approach for rubber volume model application showed better performance for volume prediction than a combined land use/cover and rubber volume classification technique, thus providing a useful tool for displaying rubber stand volume within segments or spatial units across the landscape. The combined use of a time series of Landsat TM imagery, modified postclassification change detection, and geographic information system (GIS) techniques made it possible to produce land use/cover change matrices and rubber area change information

  3. The rubber tree genome reveals new insights into rubber production and species adaptation.

    PubMed

    Tang, Chaorong; Yang, Meng; Fang, Yongjun; Luo, Yingfeng; Gao, Shenghan; Xiao, Xiaohu; An, Zewei; Zhou, Binhui; Zhang, Bing; Tan, Xinyu; Yeang, Hoong-Yeet; Qin, Yunxia; Yang, Jianghua; Lin, Qiang; Mei, Hailiang; Montoro, Pascal; Long, Xiangyu; Qi, Jiyan; Hua, Yuwei; He, Zilong; Sun, Min; Li, Wenjie; Zeng, Xia; Cheng, Han; Liu, Ying; Yang, Jin; Tian, Weimin; Zhuang, Nansheng; Zeng, Rizhong; Li, Dejun; He, Peng; Li, Zhe; Zou, Zhi; Li, Shuangli; Li, Chenji; Wang, Jixiang; Wei, Dong; Lai, Chao-Qiang; Luo, Wei; Yu, Jun; Hu, Songnian; Huang, Huasun

    2016-01-01

    The Para rubber tree (Hevea brasiliensis) is an economically important tropical tree species that produces natural rubber, an essential industrial raw material. Here we present a high-quality genome assembly of this species (1.37 Gb, scaffold N50 = 1.28 Mb) that covers 93.8% of the genome (1.47 Gb) and harbours 43,792 predicted protein-coding genes. A striking expansion of the REF/SRPP (rubber elongation factor/small rubber particle protein) gene family and its divergence into several laticifer-specific isoforms seem crucial for rubber biosynthesis. The REF/SRPP family has isoforms with sizes similar to or larger than SRPP1 (204 amino acids) in 17 other plants examined, but no isoforms with similar sizes to REF1 (138 amino acids), the predominant molecular variant. A pivotal point in Hevea evolution was the emergence of REF1, which is located on the surface of large rubber particles that account for 93% of rubber in the latex (despite constituting only 6% of total rubber particles, large and small). The stringent control of ethylene synthesis under active ethylene signalling and response in laticifers resolves a longstanding mystery of ethylene stimulation in rubber production. Our study, which includes the re-sequencing of five other Hevea cultivars and extensive RNA-seq data, provides a valuable resource for functional genomics and tools for breeding elite Hevea cultivars. PMID:27255837

  4. Studies on the activation energy from the ac conductivity measurements of rubber ferrite composites containing manganese zinc ferrite

    NASA Astrophysics Data System (ADS)

    Hashim, Mohd.; Alimuddin; Kumar, Shalendra; Shirsath, Sagar E.; Mohammed, E. M.; Chung, Hanshik; Kumar, Ravi

    2012-11-01

    Manganese zinc ferrites (MZF) have resistivities between 0.01 and 10 Ω m. Making composite materials of ferrites with either natural rubber or plastics will modify the electrical properties of ferrites. The moldability and flexibility of these composites find wide use in industrial and other scientific applications. Mixed ferrites belonging to the series Mn(1-x)ZnxFe2O4 were synthesized for different ‘x’ values in steps of 0.2, and incorporated in natural rubber matrix (RFC). From the dielectric measurements of the ceramic manganese zinc ferrite and rubber ferrite composites, ac conductivity and activation energy were evaluated. A program was developed with the aid of the LabVIEW package to automate the measurements. The ac conductivity of RFC was then correlated with that of the magnetic filler and matrix by a mixture equation which helps to tailor properties of these composites.

  5. Chemistry of rubber processing and disposal.

    PubMed Central

    Bebb, R L

    1976-01-01

    The major chemical changes during the processing of rubber occur with the breakdown in mastication and during vulcanization of the molded tire. There is little chemical change during the compounding, calendering, extrusion, and molding steps. Reclaiming is the process of converting scrap rubber into an unsaturated, processible product that can be vulcanized with sulfur. Pyrolysis of scrap rubber yields a complex mixture of liquids, gas, and residue in varying ratios dependent on the nature of the scrap and the conditions of pyrolysis. PMID:799964

  6. Graphene networks and their influence on free-volume properties of graphene-epoxidized natural rubber composites with a segregated structure: rheological and positron annihilation studies.

    PubMed

    He, Canzhong; She, Xiaodong; Peng, Zheng; Zhong, Jieping; Liao, Shuangquan; Gong, Wei; Liao, Jianhe; Kong, Lingxue

    2015-05-14

    Epoxidized natural rubber-graphene (ENR-GE) composites with segregated GE networks were successfully fabricated using the latex mixing combined in situ reduced technology. The rheological behavior and electrical conductivity of ENR-GE composites were investigated. At low frequencies, the storage modulus (G') became frequency-independent suggesting a solid-like rheological behavior and the formation of GE networks. According to the percolation theory, the rheological threshold of ENR-GE composites was calculated to be 0.17 vol%, which was lower than the electrical threshold of 0.23 vol%. Both percolation thresholds depended on the evolution of the GE networks in the composites. At low GE concentrations (<0.17 vol%), GE existed as individual units, while a "polymer-bridged GE network" was constructed in the composites when GE concentrations exceeded 0.17 vol%. Finally, a "three-dimensional GE network" with percolation conductive paths was formed with a GE concentration of 0.23 vol%, where a remarkable increase in the conductivity of ENR-GE composites was observed. The effect of GE on the atom scale free-volume properties of composites was further studied by positron annihilation lifetime spectroscopy and positron age momentum correlation measurements. The motion of ENR chains was retarded by the geometric confinement of "GE networks", producing a high-density interfacial region in the vicinity of GE nanoplatelets, which led to a lower ortho-positronium lifetime intensity and smaller free-volume hole size. PMID:25881784

  7. Preparation and pre-characterization of epoxidized natural rubber (ENR) / poly(vinylidene fluoride) (PVDF) (ENR/PVDF) thin film composite membrane

    NASA Astrophysics Data System (ADS)

    Mod, Norliyana; Othaman, Rizafizah

    2015-09-01

    Epoxidised Natural Rubber (ENR) / Poly (Vinylidene Fluoride) (PVDF) (ENR/PVDF) (60:40 wt%) thin film composite membrane was prepared by using solution casting technique. The focuses of this paper are to prepare ENR/PVDF membrane with ratio of ENR to PVDF 60:40 wt%, and to study the effectiveness of treating Palm Oil Mill Effluent (POME) using the membrane. The prepared membrane was analyzed using optical microscope and the treatment of POME was investigated using dead-end stirred cell. Treated and untreated POME was analyzed to test the percentage of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) removal. Optical microscope micrographs showed that the surface of the membrane was slightly uneven. The rate of flux which passed through the membrane was 0.60 L/hm2. Both BOD and COD decreased by 23.6 % and 49.32 % respectively, after single treatment. This showed that the membrane can be used for POME treatment. The value of BOD and COD removal can be increased by recycling the treated POME for more than two cycles, which will be further studied by authors.

  8. In vitro induction of polyploidy and chromatid exchanges by culture medium extracts of natural rubbers compounded with 2-mercaptobenzothiazole as a positive control candidate for genotoxicity tests.

    PubMed

    Matsuoka, Atsuko; Isama, Kazuo; Tsuchiya, Toshie

    2005-11-01

    We tested extracts of custom-made natural rubber samples for cytotoxicity using V79 cells and for chromosome aberration (CA) induction using CHL cells in compliance with the Japanese guidelines for basic biological tests of medical materials and devices. The samples were formulated with a high level of 2-mercaptobenzothiazole (MBT) (A); a low level of MBT (B); or zinc dibutyldithiocarbamate (ZDBC) (C). In the CA test, MBT induced mainly polyploidy, including endoreduplication, and ZDBC induced structural CAs. In the cytotoxicity test, culture medium extracts of A, B, and C suppressed colony formation to 50% of the control value at 53.1%, 94.3%, and >100%, respectively. Culture medium extracts of sample A induced polyploidy and structural CAs in the absence of an exogenous metabolic activation system (S9 mix), but at lower concentrations in its presence, indicating the existence of other leachable promutagens. The extracts of sample B induced structural CAs at the highest concentration and only with S9 mix. Sample C was negative. The facts suggest that sample A may be a candidate for a positive control for genotoxicity tests. The high frequency of polyploidy induced by sample A was not predicted by MBT, suggesting the usefulness of the test for safety evaluation of medical devices. Numerical CAs induced by MBT and sample A are discussed. PMID:16088893

  9. Impact of aluminum chloride on process performance and microbial community structure of granular sludge in an upflow anaerobic sludge blanket reactor for natural rubber processing wastewater treatment.

    PubMed

    Thanh, Nguyen Thi; Watari, Takahiro; Thao, Tran Phuong; Hatamoto, Masashi; Tanikawa, Daisuke; Syutsubo, Kazuaki; Fukuda, Masao; Tan, Nguyen Minh; Anh, To Kim; Yamaguchi, Takashi; Huong, Nguyen Lan

    2016-01-01

    In this study, granular sludge formation was carried out using an aluminum chloride supplement in an upflow anaerobic sludge blanket (UASB) reactor treating natural rubber processing wastewater. Results show that during the first 75 days after the start-up of the UASB reactor with an organic loading rate (OLR) of 2.65 kg-COD·m(-3)·day(-1), it performed stably with a removal of 90% of the total chemical oxygen demand (COD) and sludge still remained in small dispersed flocs. However, after aluminum chloride was added at a concentration of 300 mg·L(-1) and the OLR range was increased up to 5.32 kg-COD·m(-3)·day(-1), the total COD removal efficiency rose to 96.5 ± 2.6%, with a methane recovery rate of 84.9 ± 13.4%, and the flocs began to form granules. Massively parallel 16S rRNA gene sequencing of the sludge retained in the UASB reactor showed that total sequence reads of Methanosaeta sp. and Methanosarcina sp., reported to be the key organisms for granulation, increased after 311 days of operation. This indicates that the microbial community structure of the retained sludge in the UASB reactor at the end of the experiment gave a good account of itself in not only COD removal, but also granule formation. PMID:27438256

  10. Modified Asphalt Binder with Natural Zeolite for Warm Mix Asphalt

    NASA Astrophysics Data System (ADS)

    Dubravský, Marián; Mandula, Ján

    2015-11-01

    In recent years, warm mix asphalt (WMA) is becoming more and more used in the asphalt industry. WMA provide a whole range of benefits, whether economic, environmental and ecological. Lower energy consumption and less pollution is the most advantages of this asphalt mixture. The paper deals with the addition of natural zeolite into the sub base asphalt layers, which is the essential constituent in the construction of the road. Measurement is focused on basic physic - mechanical properties declared according to the catalog data sheets. The aim of this article is to demonstrate the ability of addition the natural zeolite into the all asphalt layers of asphalt pavement. All asphalt mixtures were compared with reference asphalt mixture, which was prepared in reference temperature.

  11. Electrokinetics of natural and mechanically modified ripidolite and beidellite clays

    SciTech Connect

    Sondi, I.; Pravdic, V.

    1996-08-10

    Particles of clay minerals were studied due to their importance in geochemical processes in natural waters, such as adsorption and transfer of ionic contaminants, stabilization by organics, and flocculation and sedimentation phenomena. Information on the behavior of clays was sought by experiments with model systems. Measurements of electrophoretic mobilities in relation to pH, at varying concentrations of well-characterized fulvic acid (FA), were performed on two structurally well defined, representative clay minerals prepared with clean surfaces: ripidolite (a well-known trioctahedral nonswelling chlorite) and beidellite (a typical dioctahedral smectite). Natural ripidolite and beidellite show high negative electrokinetic potentials in the range pH 2 ({minus}10 and {minus}20 mV, respectively) to pH 10 ({minus}60 and {minus}50 mV, respectively). Experiments utilizing mechanical particle disintegration (dry milling), mimicking natural wear and physical weathering, resulted in increases of specific surface area (12.3 and 1.5 times, respectively) and of cation exchange capacity (3.2 and 1.2 times, respectively). Such small-sized particles, shown by SEM figures, retain their crystal structure (X ray) and the nature of their structural bonds (FTIR), exhibiting an IEP (at pH 6.0 and 3.0, respectively). This was interpreted to be the creation of positively charged edge surfaces. Exposed to fulvic acid in solutions of 10{sup {minus}3} NaCl at pH = 6.5, these new surfaces showed an increase in negative {zeta}-potential for ripidolite, and, to a smaller extent, for beidellite. In the interaction of clay mineral particles with aqueous medium, it is concluded that the degree of mechanical wear is more decisive than the type of the mineral.

  12. Enzymatic synthesis of rubber polymer in Hevea brasiliensis

    SciTech Connect

    Tang, F.; Hu, S.; Benedict, C.R. )

    1991-05-01

    Light and Dennis purified serum soluble rubber transferase from Hevea latex to homogeneity. Prenyl transferase co-purified with rubber transferase. In the absence of washed rubber particles (WRP) the prenyl transferase catalyzed the formation of trans FPP from DMAPP and IPP. In the presence of WRP the transferase catalyzed cis additions of IPP to pre-existing rubber chains. Control mixtures of WRP, Mg{sup 2+} and FPP were not included to test for the contributions of the bound rubber transferase on WRP to the incorporation of IPP into polyisoprene. Bound rubber transferase catalyzes the repetitive addition of IPP to allylic-PP starter molecules to form polyisoprene. The order of utilization of allylic-PP starters was GGPP > FPP > GPP > DMAPP. The authors have shown that the polyisoprene enzymatically synthesized on WRP is a bimodal polymer consisting of different mol wt rubber chains similar to the polymeric characteristics of natural rubber. The bound rubber transferase was solubilized with Chaps and purified on DEAE-cellulose. The polymerization reaction catalyzed by the purified preparation showed a 98% requirement for pre-existing rubber chains. Results suggest that the prenyl transferase from Hevea serum may be part of the polymer starter system furnishing allylic-PP for the bound rubber transferase.

  13. Effect of the mosquito repellent DEET and long-wave ultraviolet radiation on permeation of the herbicide 2,4-D and the insecticide DDT in natural rubber gloves.

    PubMed

    Moody, R P; Nadeau, B

    1992-07-01

    Studies were conducted to determine the effect of a commonly used insect repellent, DEET (N,N-diethyl-m-toluamide), on the permeability of rubber gloves used as chemical protective clothing (CPC) by pesticide applicators. Glove permeation analysis was conducted with an automated in vitro diffusion analysis (AIDA) method employing an in-house, flow-through permeation cell design. Permeation of 14C-ring-labeled 2,4-D (2,4-dichlorophenoxyacetic acid) in natural rubber glove material was 2.4 +/- 1.81% at 48 hr after treatment of the glove with 2,4-D applied with DEET; this was not significantly different (Student's t-test; p less than 0.05) from 3.2 +/- 3.46% permeation of 2,4-D observed without DEET. Similarly, there was no significant difference between the permeation of pp'-DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane) applied with DEET (11.7 +/- 5.02%) and without DEET (11.4 +/- 4.86%) to natural rubber glove material. Scanning electron microscopy of the natural rubber glove material, however, demonstrated disruption of the surface ultrastructure following a 24-hr treatment with DEET. The AIDA analysis also suggested that exposure of the glove material to long-wave ultraviolet (UVA) radiation enhanced the glove permeability to 2,4-D (6.2 +/- 0.73% [+UVA]; 0.3% +/- 0.14% [-UVA]) but had no effect on the permeation of DDT. Because the CPC of pesticide applicators is commonly exposed to solar UVA, this finding may raise concerns about the efficacy and safety of CPC in general. PMID:1496935

  14. Nonaqueous ozonation of vulcanized rubber

    DOEpatents

    Serkiz, Steven M.

    1999-01-01

    A process and resulting product is provided in which a solid particulate, such as vulcanized crumb rubber, has the surface functional groups oxidized by ozonation using a nonpolar solvent. The ozonation process renders the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger loading levels of the treated crumb rubber can be used in new rubber mixtures.

  15. Nonaqueous ozonation of vulcanized rubber

    SciTech Connect

    Serkiz, S.M.

    1999-12-07

    A process and resulting product are provided in which a solid particulate, such as vulcanized crumb rubber, has the surface functional groups oxidized by ozonation using a nonpolar solvent. The ozonation process renders the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger loading levels of the treated crumb rubber can be used in new rubber mixtures.

  16. PTFE-Based Rubber Composites for Tribological Applications

    NASA Astrophysics Data System (ADS)

    Khan, M. S.; Heinrich, G.

    The unique properties of rubber, along with its diverse applications, have prompted a great deal of interest among researchers to explore advanced multifunctional materials for special purpose applications by incorporating various filler materials into the rubber matrix. This article deals with the application of a relatively new class of materials based on the addition of polytetrafluoroethylene (PTFE) powder to rubber matrixes for preparing PTFE-based elastomeric composites. Besides other properties, the remarkably low friction coefficient of PTFE enables its utilization for tribological applications. However, PTFE in rubbers has not been fully explored, mainly due to its inherent chemical inertness and incompatibility. The present work describes the electron modification of PTFE powder to improve its compatibility with rubber matrixes, the state of the art regarding its application in rubbers, and the preparation of PTFE-based elastomeric composites for tribological applications. It has been demonstrated that, in addition to the improvement in engineering properties, the chemical coupling of modified PTFE powder with rubber matrixes can significantly improve the friction and wear properties of the host elastomer. In addition, a new class of chloroprene composites, with exceptional mechanical and dispersion properties due to chemical coupling of electron-modified PTFE particles and chloroprene rubbers, has been produced. An explanation of the proposed chemical reaction mechanism between the irradiated PTFE and chloroprene rubber, along with a detailed characterization of the compatibility, dispersion, and chemical coupling is presented.

  17. Guayule resin detection and influence on guayule rubber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guayule (Parthenium argentatum) is a natural rubber (cis-1,4-polyisoprene) producing crop, native to North America. Guayule also produces organic resins, complex mixtures of terpenes, triglycerides, guayulins, triterpenoids and other components. During natural rubber extraction, guayule resins can b...

  18. A quinozolinone derivative as a novel rubber additive

    SciTech Connect

    Roy, B.C.; Khanra, T.K.; Maiti, S.; Adhikari, B.

    1993-12-31

    A new quinozolinone derivative containing -NH and -SH functional sites has been developed as a novel antioxidant for diene rubbers. A sulfenamide derivative was prepared from the above compound which acts as an excellent accelerator cum antioxidant for natural rubber. This sulfenamide compound even when used at 50% concentration of the combined amount of commercial accelerator (CBS) and antioxidant (MBI) exhibits comparable accelerating characteristics and superior antiaging performance in the vulcanization of natural rubber. This dual function sulfenamide promises to offer better dispersion in the rubber matrix than two separate chemicals - one accelerator and the other antioxidant - used commercially.

  19. Characterization of lead sorption by the natural and Fe(III)-modified zeolite

    NASA Astrophysics Data System (ADS)

    Kragović, Milan; Daković, Aleksandra; Marković, Marija; Krstić, Jugoslav; Gatta, G. Diego; Rotiroti, Nicola

    2013-10-01

    The influence of contact time, temperature and particle size on lead sorption by the natural and Fe(III)-modified zeolites was investigated. Characterization of the natural and Fe(III)-modified zeolite before and after lead sorption was performed by determination of textural properties, by scanning electron microscopy and X-ray spectroscopy in energy-dispersive mode (SEM-EDS), transmission electron microscopy (TEM) and X-ray powder diffraction (XRPD) analysis. Lead sorption kinetics at 303-333 K, best represented by the pseudo-second order model and activation energy (13.5 and 8.5 kJ/mol for the natural and Fe(III)-modified zeolite respectively) confirmed an activated chemical sorption. Desorption experiments indicated that lead was irreversibly sorbed on both zeolites. XRPD, TEM and SEM results showed that modification of the natural zeolite with Fe(III) ions did not change its crystal structure and iron is mainly located at the zeolite surface, likely in form of amorphous iron oxy-hydroxides. Specific surface area significantly increases after modification of the natural zeolite with Fe(III) ions (from 30.2 for the natural to 52.5 m2/g for Fe(III)-modified zeolite). Characterization of both lead saturated sorbents suggested that besides ion exchange, lead is both chemisorbed and precipitated at their surfaces, and presence of amorphous iron in Fe(III)-modified zeolite favors sorption of lead.

  20. The Potential for Sunflower as a Rubber-Producing Crop for the United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There are strategic as well as economic incentives to develop a renewable, United States-based supply of natural rubber. Currently, nearly all commercial natural rubber comes from a single species, the Brazilian rubber tree (Hevea brasiliensis) and the US is almost completely dependent on imports ...

  1. Modified natural diatomite and its enhanced immobilization of lead, copper and cadmium in simulated contaminated soils.

    PubMed

    Ye, Xinxin; Kang, Shenghong; Wang, Huimin; Li, Hongying; Zhang, Yunxia; Wang, Guozhong; Zhao, Huijun

    2015-05-30

    Natural diatomite was modified through facile acid treatment and ultrasonication, which increased its electronegativity, and the pore volume and surface area achieved to 0.211 cm(3) g(-1) and 76.9 m(2) g(-1), respectively. Modified diatomite was investigated to immobilize the potential toxic elements (PTEs) of Pb, Cu and Cd in simulated contaminated soil comparing to natural diatomite. When incubated with contaminated soils at rates of 2.5% and 5.0% by weight for 90 days, modified diatomite was more effective in immobilizing Pb, Cu and Cd than natural diatomite. After treated with 5.0% modified diatomite for 90 days, the contaminated soils showed 69.7%, 49.7% and 23.7% reductions in Pb, Cu and Cd concentrations after 0.01 M CaCl2 extraction, respectively. The concentrations of Pb, Cu and Cd were reduced by 66.7%, 47.2% and 33.1% in the leaching procedure, respectively. The surface complexation played an important role in the immobilization of PTEs in soils. The decreased extractable metal content of soil was accompanied by improved microbial activity which significantly increased (P<0.05) in 5.0% modified diatomite-amended soils. These results suggested that modified diatomite with micro/nanostructured characteristics increased the immobilization of PTEs in contaminated soil and had great potential as green and low-cost amendments. PMID:25725344

  2. Predicting the glass transition temperature as function of crosslink density and polymer interactions in rubber compounds

    NASA Astrophysics Data System (ADS)

    D'Escamard, Gabriella; De Rosa, Claudio; Auriemma, Finizia

    2016-05-01

    Crosslink sulfur density in rubber compounds and interactions in polymer blends are two of the composition elements that affect the rubber compound properties and glass transition temperature (Tg), which is a marker of polymer properties related to its applications. Natural rubber (NR), butadiene rubber (BR) and styrene-butadiene rubber (SBR) compounds were investigated using calorimetry (DSC) and dynamic mechanical analysis (DMA). The results indicate that the Di Marzio's and Schneider's Models predict with accuracy the dependence of Tg on crosslink density and composition in miscible blends, respectively, and that the two model may represent the base to study the relevant "in service" properties of real rubber compounds.

  3. Overview of the rubber industry and tire manufacturing.

    PubMed

    Lewis, R

    1999-01-01

    The production of rubber and rubber products is a large and diverse industry. Natural rubber, obtained from plantations in Africa and Asia, accounts for only about 25% of the rubber used in industry. Synthetic alternatives, developed during World War II, are the primary sources of raw materials today. Health hazards in synthetic rubber production are primary related to exposure to monomers. An excess incidence of leukemia has been observed in styrene/butadiene rubber production, attributed to exposure to 1,3-butadiene. Excesses of cancer and respiratory disease have been reported, although specific causative agents are rarely identified. Exposures have varied greatly over the years, based on changes in materials used, work practices, and ventilation. In modern industry, exposures to noise, skin and respiratory irritants, and ergonomic stressors remain important. The tire industry, in particular, has been studied extensively over the past 50 years. PMID:10495481

  4. Rubber Band Science

    ERIC Educational Resources Information Center

    Cowens, John

    2005-01-01

    Not only are rubber bands great for binding objects together, but they can be used in a simple science experiment that involves predicting, problem solving, measuring, graphing, and experimenting. In this article, the author describes how rubber bands can be used to teach the force of mass.

  5. Biological feedstock development as part of the domestication and commercialization of Taraxacum kok-saghyz, a potential domestic source of natural rubber and inulin: progress and outlook

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wild-collected F0 seed was found to contain a mixture Taraxacum species (i.e., highly variable seedling phenotypes), a likely drag on TKS germplasm enhancement. Also, roots of unselected, wild-collected Taraxacum genotypes were found to contain, on average, 1.4 and 56.4 percent rubber and inulin, re...

  6. Molecular aggregates of Merocyanine 540 in aqueous suspensions containing natural and CTAB-modified bentonite

    NASA Astrophysics Data System (ADS)

    Kaya, Mehmet; Meral, Kadem; Onganer, Yavuz

    2015-03-01

    The molecular interactions of MC-540 (Merocyanine 540) in clay suspensions containing natural bentonite and CTAB (cetyl trimethyl ammonium bromide)-modified bentonite were examined by using absorption, steady-state and time-resolved fluorescence spectroscopies. Strong affinity of clays for dye adsorption caused the strong interaction of MC-540 molecules with bentonite particles in aqueous dispersion. The interaction of dye with natural bentonite and CTAB-modified bentonite particles in aqueous dispersion caused significant changes in the photophysical properties of MC-540 when they were compared to those in pure water. Spectral data revealed that monomer, H-dimer and H-aggregate of MC-540 in the clay aqueous dispersions were formed depending on dye concentration. Moreover, H-aggregates of dye were predominantly formed in the CTAB-modified bentonite aqueous suspension. The presence of H-aggregates strongly decreased the fluorescence lifetime of MC-540.

  7. The Functional Identification of Rubber Biosynthetic Genes in Plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber (cis-1,4-polyisoprene) is an essential plant derived raw material required for the manufacture of numerous industrial and medical related products. This elastic polymer is synthesized and sequestered within cytosolic vesicles known as rubber particles. When provided with farnesyl-pyro...

  8. TROPHIC STRUCTURE, REPRODUCTIVE SUCCESS, AND GROWTH RATE OF FISHES IN A NATURAL AND MODIFIED HEADWATER STREAM

    EPA Science Inventory

    The impact of removing riparian vegetation, channel straightening, and fluctuations in flow regime on trophic structure, reproductive success, and growth rate of fishes was assessed in a natural (Jordan Creek(JC)) and modified (Big Ditch(BD)) headwater stream in eastcentral Illin...

  9. Transcriptome and gene expression analysis in cold-acclimated guayule (Parthenium argentatum)rubber-producing tissue

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber biosynthesis in guayule (Parthenium argentatum) is associated with moderately cold night temperatures. To begin to dissect the molecular events triggered by cold temperatures that govern rubber synthesis induction in guayule, the transcriptome of bark tissue, where rubber is produced...

  10. The rubber tree genome shows expansion of gene family associated with rubber biosynthesis.

    PubMed

    Lau, Nyok-Sean; Makita, Yuko; Kawashima, Mika; Taylor, Todd D; Kondo, Shinji; Othman, Ahmad Sofiman; Shu-Chien, Alexander Chong; Matsui, Minami

    2016-01-01

    Hevea brasiliensis Muell. Arg, a member of the family Euphorbiaceae, is the sole natural resource exploited for commercial production of high-quality natural rubber. The properties of natural rubber latex are almost irreplaceable by synthetic counterparts for many industrial applications. A paucity of knowledge on the molecular mechanisms of rubber biosynthesis in high yield traits still persists. Here we report the comprehensive genome-wide analysis of the widely planted H. brasiliensis clone, RRIM 600. The genome was assembled based on ~155-fold combined coverage with Illumina and PacBio sequence data and has a total length of 1.55 Gb with 72.5% comprising repetitive DNA sequences. A total of 84,440 high-confidence protein-coding genes were predicted. Comparative genomic analysis revealed strong synteny between H. brasiliensis and other Euphorbiaceae genomes. Our data suggest that H. brasiliensis's capacity to produce high levels of latex can be attributed to the expansion of rubber biosynthesis-related genes in its genome and the high expression of these genes in latex. Using cap analysis gene expression data, we illustrate the tissue-specific transcription profiles of rubber biosynthesis-related genes, revealing alternative means of transcriptional regulation. Our study adds to the understanding of H. brasiliensis biology and provides valuable genomic resources for future agronomic-related improvement of the rubber tree. PMID:27339202

  11. The rubber tree genome shows expansion of gene family associated with rubber biosynthesis

    PubMed Central

    Lau, Nyok-Sean; Makita, Yuko; Kawashima, Mika; Taylor, Todd D.; Kondo, Shinji; Othman, Ahmad Sofiman; Shu-Chien, Alexander Chong; Matsui, Minami

    2016-01-01

    Hevea brasiliensis Muell. Arg, a member of the family Euphorbiaceae, is the sole natural resource exploited for commercial production of high-quality natural rubber. The properties of natural rubber latex are almost irreplaceable by synthetic counterparts for many industrial applications. A paucity of knowledge on the molecular mechanisms of rubber biosynthesis in high yield traits still persists. Here we report the comprehensive genome-wide analysis of the widely planted H. brasiliensis clone, RRIM 600. The genome was assembled based on ~155-fold combined coverage with Illumina and PacBio sequence data and has a total length of 1.55 Gb with 72.5% comprising repetitive DNA sequences. A total of 84,440 high-confidence protein-coding genes were predicted. Comparative genomic analysis revealed strong synteny between H. brasiliensis and other Euphorbiaceae genomes. Our data suggest that H. brasiliensis’s capacity to produce high levels of latex can be attributed to the expansion of rubber biosynthesis-related genes in its genome and the high expression of these genes in latex. Using cap analysis gene expression data, we illustrate the tissue-specific transcription profiles of rubber biosynthesis-related genes, revealing alternative means of transcriptional regulation. Our study adds to the understanding of H. brasiliensis biology and provides valuable genomic resources for future agronomic-related improvement of the rubber tree. PMID:27339202

  12. Recycling of plastic and rubber tire waste in asphalt pavements

    SciTech Connect

    Morrison, G.R.; Lee, N.K.; Hesp, S.A.M.

    1994-12-31

    This paper discusses some important issues related to the use of recycled thermoplastics and rubber tire waste in asphalt binders for hot-mix pavements. Both high temperature rheological and low temperature fracture studies are presented on recycled polyethylene, devulcanized and crumb rubber-modified asphalt binders. The results are compared to unmodified and commercially available modified binders. This research is especially timely in light of the US Intermodal Surface Transportation Efficiency Act of 1991, Section 1038 which, starting in 1995, will force state and local governments to use significant amounts of recycled rubber tire or plastic waste in federally funded highway projects. High temperature rheological measurements of the loss modulus, loss tangent and complex modulus show a significant improvement when only small quantities of crumb rubber, devulcanized crumb rubber or waste polyethylene are added to the asphalt binders. The low temperature fracture performance of the modified asphalts is greatly influenced by the interfacial strength between the dispersed and continuous phase. The fracture toughness increases dramatically, only when low molecular weight polymers are grafted in-situ onto the rubber and polymer dispersed phases in order to strength the interface. This points to a crack-pinning mechanism as being responsible for the dramatic increase in fracture toughness that is observed in this work. Single phase, devulcanized crumb rubber-asphalt systems perform quite poorly at low temperatures.

  13. Coatings for rubber bonding and paint adhesion

    NASA Astrophysics Data System (ADS)

    Boulos, M. S.; Petschel, M.

    1997-08-01

    Conversion coatings form an important base for the adhesion of paint to metal substrates and for the bonding of rubber to metal parts. Four types of conversion coatings were assessed as base treatments for the bonding of rubber to steel and for the corrosion protection of metal substrates under paint: amorphous iron phosphate, heavy zinc phosphate, and three types of modified zinc phosphates that utilized one or more metal cations in addition to zinc. When applied, these conversion coatings formed a thin film over the metal substrate that was characterized by scanning electron microscopy, x-ray diffraction, and chemical methods. The performance of the coatings was assessed using physical methods such as dry adhesion, conical mandrel, impact, and stress adhesion for the rubber-bonded parts, and by corrosion resistance methods such as humidity, salt spray, and cyclic corrosion. Coating characterization and performance were correlated.

  14. Study on mechanical properties of laminated rubber bearing with small shape factor

    SciTech Connect

    Mazda, T.; Ootori, Y.; Yabana, S.; Hirata, K.; Ishida, K.

    1995-12-01

    Laminated rubber bearings with a small shape factor are regarded as one of the most promising isolation devices to reduce the vertical seismic load of a nuclear power plant. In this study, three types of natural rubber bearings with different aspect ratios (diameter/total thickness of rubber) and one high-damping rubber bearing are tested under varied loading conditions. Basic characteristics and ultimate characteristics of the bearings are made clear, and applicability of estimation formula and analysis method are verified.

  15. US rubber markets recover

    SciTech Connect

    Wood, A.

    1993-02-03

    Synthetic rubber markets in North America bounced back in no uncertain terms last year, with demand climbing an impressive 9.5%, to 2.97 million m.t.; and, according to the International Institute of Synthetic Rubber Producers (IIS-RP; Houston) latest five-year forecast, producers can look forward to a 3.3% increase in demand during 1993. This growth rate outpaced out 1992 forecast and demonstrates the resilience of the synthetic rubber industry, says William E. Tessemer, managing director of IISRP. We expect demand in 1993 to surpass 1992 and level off at a 2%/year growth rate for synthetic rubber - 2.5% including thermoplastic elastomers [TPEs]-over the 1993-97 period. The improvement reflects signs of a recovery in North America, especially the pickup in the auto and tire industry. The two major tire rubbers - styrene butadiene and polybutadiene rubber - notched up double-digit gains, and other materials that have autos uses, such as nitrile rubber and many of the specialty elastomers, also advanced strongly.

  16. New rubber qualification for the igniter adapter

    NASA Technical Reports Server (NTRS)

    Humpherys, Mark A.

    1994-01-01

    Kirkhill Rubber Company (KRC) has informed Thiokol Corporation that two raw materials used in the asbestos and silica filled acrylonitrile butadience rubber (NBR) formulation per STW 2621 are no longer available from their vendors. Agerite White (Di-beta-naphthyl-paraphenylene diamine), manufactured by B. F. Goodrich, is an antioxidant used in NBR. This raw material makes up roughly 1-2 percent of the finished product. KRC proposed that this raw material be replaced by Agerite Stalite S (mixture of octylated diphenylamines) distributed by R. T. Vanderbilt Co. Protox-166 zinc oxide, manufactured by Zinc Corporation of America, is an activator currently used in NBR. This material also makes up about 1-2 percent of the finished material. Protox-166 is an American process grade zinc oxide. It is proposed by KRC to replace Protox-166 with Kadox-930C, a French process grade zinc oxide. American process grades have an ASTM minimum purity of 99.0 percent; the French process grades have a minimum purity of 99.5 percent. Previous testing per WTP-0270 has demonstrated that the mechanical and thermal properties of the rubber with the new ingredients are comparable to the 'old' rubber. The test results are reported in TWR-61790. One igniter adapter, Part no. 7U77562-02 serial no. 2 was insulated per ETP-1206 using the new rubber formulation and a modified lay up and cure method to demonstrate that there is no impact on this process. The results of this demonstration are reported.

  17. Removal of lead from aqueous solutions by using the natural and Fe(III)-modified zeolite

    NASA Astrophysics Data System (ADS)

    Kragović, Milan; Daković, Aleksandra; Sekulić, Živko; Trgo, Marina; Ugrina, Marin; Perić, Jelena; Gatta, G. Diego

    2012-02-01

    In the present study, the sorption of lead by the natural and Fe(III)-modified zeolite (clinoptilolite) is described. The characterization of the natural zeolite-rich rock and the Fe(III)-modified form was performed by chemical analysis, point of the zero charge (pHpzc), X-ray powder diffraction, applying the Rietveld/RIR method for the quantitative phase analysis, and scanning electron microscopy. The effects of sorbents dose and the initial lead concentrations on its sorption by two sorbents were investigated. For both sorbents, it was determined that at lower initial concentrations of lead, ion exchange of inorganic cations in zeolites with lead, together with uptake of hydrogen dominated, while at higher initial lead concentrations beside these processes, chemisorption of lead occurred. Significantly higher sorption of lead was achieved with Fe(III)-modified zeolite. From sorption isotherms, maximum sorbed amounts of lead, under the applied experimental conditions, were 66 mg/g for the natural and 133 mg/g for Fe(III)-modified zeolite. The best fit of experimental data was achieved with the Freundlich model (R2 ≥ 0.94).

  18. The enzymatic synthesis of rubber polymer in Parthenium argentatum Gray

    SciTech Connect

    Benedict, C.R.; Madhavan, S.; Greenblatt, G.A.; Venkatachalam, K.V.; Foster, M.A. )

    1990-03-01

    Washed rubber particles isolated from stem homogenates of Parthenium argentatum Gray by ultracentrifugation and gel filtration on columns of LKB Ultrogel AcA34 contain rubber transferase which catalyzes the polymerization of isopentenyl pyrophosphate into rubber polymer. The polymerization reaction requires Mg{sup 2+} isopentenyl pyrophosphate, and an allylic pyrophosphate. The K{sub m} values for Mg{sup 2+}, isopentenyl pyrophosphate, and dimethylallyl pyrophosphate were 5.2 {times} 10{sup {minus}4} molar, 8.3 {times} 10{sup {minus}5} molar, and 9.6 {times} 10{sup {minus}5} molar, respectively. The molecular characteristics of the rubber polymer synthesized from ({sup 14}C)isopentenyl pyrophosphate were examined by gel permeation chromatography. The peak molecular weight of the radioactive polymer increased from 70,000 in 15 minutes to 750,000 in 3 hours. The weight average molecular weight of the polymer synthesized over a 3 hour period was 1.17 {times} 10{sup 6} compared to 1.49 {times} 10{sup 6} for the natural rubber polymer extracted from the rubber particles. Over 90% of the in vitro formation of the rubber polymer was de novo from dimethylallyl pyrophosphate and isopentenyl pyrophosphate. Treatment of the washed rubber particles with 3-((3-cholamidopropyl) dimethylammonio) -1-propanesulfonate solubilized the rubber transferase. The solubilized enzyme(s) catalyzed the polymerization of isopentenyl pyrophosphate into rubber polymer with a peak molecular weight of 1 {times} 10{sup 5} after 3 hours of incubation with Mg{sup 2+} and dimethylallyl pyrophosphate. The data support the conclusion that the soluble preparation of rubber transferase is capable of catalyzing the formation of a high molecular weight rubber polymer from an allylic pyrophosphate initiator and isopentenyl pyrophosphate monomer.

  19. Biolubricant induced phase inversion and superhydrophobicity in rubber-toughened biopolymer/organoclay nanocomposites

    NASA Astrophysics Data System (ADS)

    Bayer, Ilker S.; Steele, Adam; Martorana, Philip; Loth, Eric; Robinson, Scott J.; Stevenson, Darren

    2009-08-01

    We present a simple technique to fabricate rubber-toughened biopolymer/organoclay nanocomposite coatings with highly water repellent surface wetting characteristics and strong adhesion to metal surfaces. The technique combines the principles of phase inversion and atomization of multicomponent polymer/organoclay suspensions containing a biolubricant as the nonsolvent. The biolubricant was a blend of cyclomethicone/dimethiconol oil with fruit kernel oils. The ternary system of cellulose nitrate/solvent/biolubricant was blended with rubber dispersed organoclay nanofluids. Natural, synthetic, and fluoroacrylic latex rubbers were used for the purpose. Self-cleaning superhydrophobic coatings were obtained from synthetic and fluoroacrylic rubbers whereas natural rubber containing formulations resulted in sticky superhydrophobic coatings.

  20. Thiazole/oxazole-modified microcins: complex natural products from ribosomal templates

    PubMed Central

    Melby, Joel O.; Nard, Nathan J.; Mitchell, Douglas A.

    2014-01-01

    With billions of years of evolution under its belt, Nature has been expanding and optimizing its biosynthetic capabilities. Chemically complex secondary metabolites continue to challenge and inspire today’s most talented synthetic chemists. A brief glance at these natural products, especially the substantial structural variation within a class of compounds, clearly demonstrates that Nature has long played the role of medicinal chemist. The recent explosion in genome sequencing has expanded our appreciation of natural product space and the vastness of uncharted territory that remains. One small corner of natural product chemical space is occupied by the recently dubbed thiazole/oxazole-modified microcins (TOMMs), which are ribosomally produced peptides with posttranslationally installed heterocycles derived from cysteine, serine and threonine residues. As with other classes of natural products, the genetic capacity to synthesize TOMMs has been widely disseminated among bacteria. Over the evolutionary timescale, Nature has tested countless random mutations and selected for gain of function in TOMM biosynthetic gene clusters, yielding several privileged molecular scaffolds. Today, this burgeoning class of natural products encompasses a structurally and functionally diverse set of molecules (i.e. microcin B17, cyanobactins, and thiopeptides). TOMMs presumably provide their producers with an ecological advantage. This advantage can include chemical weapons wielded in the battle for nutrients, disease-promoting virulence factors, or compounds presumably beneficial for symbiosis. Despite this plethora of functions, many TOMMs await experimental interrogation. This review will focus on the biosynthesis and natural combinatorial diversity of the TOMM family. PMID:21429787

  1. Removal Of Copper From Aqueous Solutions By Using Natural And Fe-Modified Clinoptilolite

    NASA Astrophysics Data System (ADS)

    Lipovský, Marek; Sirotiak, Maroš; Soldán, Maroš

    2015-06-01

    Removal of copper from aqueous solution on the natural and modified clinoptilolite was studied under static conditions. Batch adsorptions of copper were performed to investigate the effects of contact time and initial metal ion concentration. The Freundlich and Langmuir adsorption isotherms were used to analyse the experimental data. The kinetic analyses of the adsorption processes were performed using the pseudo-first-order and pseudo-second-order kinetic models.

  2. Comparison of aluminum modified natural materials in the removal of fluoride ions.

    PubMed

    Teutli-Sequeira, A; Solache-Ríos, M; Martínez-Miranda, V; Linares-Hernández, I

    2014-03-15

    The removal behaviors of fluoride ions from aqueous solutions and drinking water by aluminum modified hematite, zeolitic tuff and calcite were determined. Drinking water containing naturally 8.29 mg of fluoride ions per liter was characterized. The hematite, zeolitic tuff and calcite were aluminum modified by an electrochemical method. The effects of contact time and the dose of adsorbent were determined. The PZC (point of zero charge) values for aluminum modified hematite, zeolitic tuff and calcite were 6.2, 5.8 and 8.4, respectively. Adsorption kinetic data were best fitted to pseudo-second-order and Elovich models and equilibrium data to Langmuir-Freundlich isotherm model. The highest fluoride sorption capacities (10.25 and 1.16 mg/g for aqueous solutions and drinking water respectively) were obtained for aluminum modified zeolite with an adsorbent dosage of 10 g/L and an initial F(-) concentration of 9 and 8.29 mg/L for aqueous solutions and drinking water respectively (the final concentrations were 0.08 and 0.7 mg/L respectively). The main mechanism involved in the adsorption of fluoride ions is chemisorption on heterogeneous materials according to the results obtained by fitting the data to kinetic and isotherm models respectively. Aluminum modified zeolitic tuff showed the best characteristics for the removal of fluoride ions from water. PMID:24461843

  3. Vertical and Horizontal Vegetation Structure across Natural and Modified Habitat Types at Mount Kilimanjaro.

    PubMed

    Rutten, Gemma; Ensslin, Andreas; Hemp, Andreas; Fischer, Markus

    2015-01-01

    In most habitats, vegetation provides the main structure of the environment. This complexity can facilitate biodiversity and ecosystem services. Therefore, measures of vegetation structure can serve as indicators in ecosystem management. However, many structural measures are laborious and require expert knowledge. Here, we used consistent and convenient measures to assess vegetation structure over an exceptionally broad elevation gradient of 866-4550 m above sea level at Mount Kilimanjaro, Tanzania. Additionally, we compared (human)-modified habitats, including maize fields, traditionally managed home gardens, grasslands, commercial coffee farms and logged and burned forests with natural habitats along this elevation gradient. We distinguished vertical and horizontal vegetation structure to account for habitat complexity and heterogeneity. Vertical vegetation structure (assessed as number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) displayed a unimodal elevation pattern, peaking at intermediate elevations in montane forests, whereas horizontal structure (assessed as coefficient of variation of number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) was lowest at intermediate altitudes. Overall, vertical structure was consistently lower in modified than in natural habitat types, whereas horizontal structure was inconsistently different in modified than in natural habitat types, depending on the specific structural measure and habitat type. Our study shows how vertical and horizontal vegetation structure can be assessed efficiently in various habitat types in tropical mountain regions, and we suggest to apply this as a tool for informing future biodiversity and ecosystem service studies. PMID:26406985

  4. Vertical and Horizontal Vegetation Structure across Natural and Modified Habitat Types at Mount Kilimanjaro

    PubMed Central

    Rutten, Gemma; Ensslin, Andreas; Hemp, Andreas; Fischer, Markus

    2015-01-01

    In most habitats, vegetation provides the main structure of the environment. This complexity can facilitate biodiversity and ecosystem services. Therefore, measures of vegetation structure can serve as indicators in ecosystem management. However, many structural measures are laborious and require expert knowledge. Here, we used consistent and convenient measures to assess vegetation structure over an exceptionally broad elevation gradient of 866–4550m above sea level at Mount Kilimanjaro, Tanzania. Additionally, we compared (human)-modified habitats, including maize fields, traditionally managed home gardens, grasslands, commercial coffee farms and logged and burned forests with natural habitats along this elevation gradient. We distinguished vertical and horizontal vegetation structure to account for habitat complexity and heterogeneity. Vertical vegetation structure (assessed as number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) displayed a unimodal elevation pattern, peaking at intermediate elevations in montane forests, whereas horizontal structure (assessed as coefficient of variation of number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) was lowest at intermediate altitudes. Overall, vertical structure was consistently lower in modified than in natural habitat types, whereas horizontal structure was inconsistently different in modified than in natural habitat types, depending on the specific structural measure and habitat type. Our study shows how vertical and horizontal vegetation structure can be assessed efficiently in various habitat types in tropical mountain regions, and we suggest to apply this as a tool for informing future biodiversity and ecosystem service studies. PMID:26406985

  5. Microwave treatment of vulcanized rubber

    DOEpatents

    Wicks, George G.; Schulz, Rebecca L.; Clark, David E.; Folz, Diane C.

    2002-07-16

    A process and resulting product is provided in which a vulcanized solid particulate, such as vulcanized crumb rubber, has select chemical bonds broken by microwave radiation. The direct application of microwaves in combination with uniform heating of the crumb rubber renders the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger particle sizes and/or loading levels of the treated crumb rubber can be used in new rubber mixtures to produce recycled composite products with good properties.

  6. Effects of surface modification to rubber particles on the toughening of polystyrene, polyester and epoxy systems

    SciTech Connect

    Hampton, J.M.; Yao, G.L.; Joseph, T.M.; Beatty, C.L.

    1996-12-31

    Preliminary work has been done for the improvement of impact properties of rubber-toughened polystyrene, rubber-toughened epoxy, and rubber-toughened polyester. Unmodified ground tire rubber particles are being compared to two types of surface-modified particles, including: Vistamer{trademark} R-4200 from Composite Particles, Inc. and a chemically digested rubber. By chemically reacting the particles with the matrix, we achieve significant improvement in impact resistance resulting from enhanced energy dispersion. Particle size and particle size distribution, studied through image analysis, is an important parameter controlling impact and fracture strength. The smaller particle size of the digested rubber composites, combined with its surface treatment, significantly improves the mechanical properties of these composites over the properties of the larger, unmodified ground rubber-toughened composites and Vistamer{trademark} surface treated composites.

  7. Vulcanization and the mechanical response of rubber

    NASA Astrophysics Data System (ADS)

    Kundurthi, S.; Mythravaruni, P.; Ravindran, P.

    2015-06-01

    Hyperelastic models are widely used to describe the mechanical response of rubber. However, purely mechanical models cannot account for changes in the material due to chemical reactions such as those that take place during vulcanization. Here, we present a model developed within a thermodynamic framework accounting for chemical reactions. A mixture theory approach that allows for the existence of multiple species and their interconversion is followed. The existence of a Helmholtz potential and a rate of entropy production function for the mixture as a whole are posited. Following the multiple natural configuration approach, the rate of entropy production is maximized to obtain constitutive equations. The viscoelastic model is then specialized to the elastic case. The model is calibrated using data available in the literature for rubber. A simulation of the stress-strain curve of rubber as vulcanization progresses is presented.

  8. Specification guidelines for flue gas desulfurization rubber: Final report

    SciTech Connect

    Cassidy, P.

    1987-11-01

    After investigating the historical performance (as of spring 1986) of rubber liners in 27 utility FGD systems and examining the causes of failures, Radian Corporation and Texas Research Institute developed user guidelines to assist in the selection and installation of rubber product systems. As part of the process, the utility should prepare a rubber lining technical job specification. This document will govern material selection and quality control measures and should include the general requirements, a description of the service conditions, rubber lining specification, technical requirements (for design, welding surface preparation, application, and inspection), and quality control requirements. Three generic classes of sheet rubber products have been commonly used as FGD liners: chlorobutyl, natural rubber, and neoprene. Of these, the rubber industry considers chlorobutyl to be the material of choice. Proposed rubber systems should be evaluated according to the utility's prior experience, objective test results in FGD systems, long-term FGD simulation tests, and accelerated screening tests as defined in this document. 49 refs., 9 figs., 9 tabs.

  9. Epoxy-rubber interactions

    SciTech Connect

    McGarry, F.J.; Rosner, R.B.

    1993-12-31

    Films containing amine-terminated butadiene-acrylonitrile (ATBN) rubber and diglycidal ether of bisphenol A (DGEBA) epoxy, cross-linked with amine curing agent, exhibit tensile extensibility over the composition range of 50-600 parts by weight rubber to 100 parts by weight epoxy. This tensile extensibility suggests the presence of ductile behavior in the second-phase particles of ATBN rubber-toughened DGEBA epoxy systems, even if the particles contain substantial amounts of epoxy. Such cured films also are capable of absorbing large additional amounts of liquid epoxy that contains the cure agent. When the epoxy is cured in situ, the film tensile behavior is consistent with the overall proportions of rubber and epoxy present. The solubility behavior also suggests that the glassy epoxy matrix immediately surrounding a precipated particle contains rubber in solid solution and thereby can plastically yield under shear-stress action. As observations confirm, such flow would be heat recoverable. 15 refs., 9 figs., 2 tabs.

  10. Dermatitis in rubber manufacturing industries

    SciTech Connect

    White, I.R.

    1988-01-01

    This review describes the history of rubber technology and the manufacturing techniques used in rubber manufacturing industries. The important aspects of the acquisition of allergic and irritant contact dermatitis within the industry are presented for the reader.

  11. Theory of powdery rubber wear

    NASA Astrophysics Data System (ADS)

    Persson, B. N. J.

    2009-12-01

    Rubber wear typically involves the removal of small rubber particles from the rubber surface. On surfaces with not too sharp roughness, e.g. most road surfaces, this involves (slow) crack propagation. In this paper I shall present a theory of mild rubber wear. I shall derive the distribution of wear particle sizes Φ(D), which is in excellent agreement with experiment. I shall also show that the calculated wear rate is consistent with experimental data for tire tread block wear.

  12. Selection of Natural and Base-Modified DNA Aptamers for a Camptothecin Derivative.

    PubMed

    Fujita, Hiroto; Kuwahara, Masayasu

    2016-01-01

    Nucleic acid aptamers for small molecules are currently being developed and have a potential role in diverse applications including biosensing, diagnostics, and therapeutics involving low-molecular-weight biomarkers and drugs. To enhance and broaden their functions through chemical modification, systematic evolution of ligands by exponential enrichment (SELEX) selection has been attempted with modified DNA/RNA libraries. Recently, we demonstrated the superior efficacy of base modification for affinity enhancement and the usefulness of unnatural nucleic acid libraries for development of small-molecule aptamers. In this unit, we describe construction of a modified DNA library that includes (E)-5-(2-(N-(2-(N(6) -adeninyl)ethyl))carbamylvinyl)uracil bases and acquisition of high-affinity camptothecin-binding DNA aptamers, in addition to those of the corresponding natural DNA library and aptamers, using the SELEX method. © 2016 by John Wiley & Sons, Inc. PMID:27248786

  13. Mechanisms controlling adsorption of natural organic matter on surfactant-modified iron oxide-coated sand.

    PubMed

    Ding, Chunli; Shang, Chii

    2010-06-01

    Mechanisms contributing to the adsorption of natural organic matter (NOM) on surfactant-modified iron oxide-coated sand (IOCS) were explored by microscopic surface characterization techniques and adsorption tests. Electrostatic interactions that were thought to be from the positively charged, surface-coated surfactant, hexadecyltrimethyl ammonium (HDTMA), seemed to be unimportant, likely because the outward-pointing tail groups of the surface-coated HDTMA monolayers hindered the interactions. Improved hydrophobic interactions followed by ligand exchange are believed to be the dominant mechanisms. Atomic force microscopy (AFM) force analysis with chemically modified tips was used to explore the adsorption mechanisms between NOM and IOCS, where an iron oxide-coated mica surface was utilized as a substitute for the IOCS surface. It demonstrates the changes of pull-on forces and the increases in hydrophobic interactions from the modification of IOCS with HDTMA. PMID:20457463

  14. Biodesulfurization of rubber materials

    SciTech Connect

    Torma, A.E. ); Raghavan, D. . Dept. of Materials Science and Engineering)

    1990-01-01

    One of the most challenging problems in municipal waste treatment is the recycling of polymeric waste materials. The present study has demonstrated the applicability of biotechnological principles in the desulfurization of rubber using shake flask and Warburg respirometric techniques. In terms of oxygen uptake and specific rate of oxygen uptake, it was found that the mixed culture of Thiobacillus ferrooxidans and Thiobacillus thiooxidans was more efficient in this process than the individual pure cultures of these bacteria. Furthermore, the mixed cultures resulted in ten times higher sulfur removals from rubber relative to those of sterile controls. Additional studies are needed to elucidate the mechanisms of biodesulfurization of rubber. It is expected that the development of this process may provide a solution to recycling of car tire materials. 32 refs., 4 figs., 3 tabs.

  15. Hydrogen bond formation between the naturally modified nucleobase and phosphate backbone

    PubMed Central

    Sheng, Jia; Zhang, Wen; Hassan, Abdalla E. A.; Gan, Jianhua; Soares, Alexei S.; Geng, Song; Ren, Yi; Huang, Zhen

    2012-01-01

    Natural RNAs, especially tRNAs, are extensively modified to tailor structure and function diversities. Uracil is the most modified nucleobase among all natural nucleobases. Interestingly, >76% of uracil modifications are located on its 5-position. We have investigated the natural 5-methoxy (5-O-CH3) modification of uracil in the context of A-form oligonucleotide duplex. Our X-ray crystal structure indicates first a H-bond formation between the uracil 5-O-CH3 and its 5′-phosphate. This novel H-bond is not observed when the oxygen of 5-O-CH3 is replaced with a larger atom (selenium or sulfur). The 5-O-CH3 modification does not cause significant structure and stability alterations. Moreover, our computational study is consistent with the experimental observation. The investigation on the uracil 5-position demonstrates the importance of this RNA modification at the atomic level. Our finding suggests a general interaction between the nucleobase and backbone and reveals a plausible function of the tRNA 5-O-CH3 modification, which might potentially rigidify the local conformation and facilitates translation. PMID:22641848

  16. Improving rubber concrete by waste organic sulfur compounds.

    PubMed

    Chou, Liang-Hisng; Lin, Chun-Nan; Lu, Chun-Ku; Lee, Cheng-Haw; Lee, Maw-Tien

    2010-01-01

    In this study, the use of crumb tyres as additives to concrete was investigated. For some time, researchers have been studying the physical properties of concrete to determine why the inclusion of rubber particles causes the concrete to degrade. Several methods have been developed to improve the bonding between rubber particles and cement hydration products (C-S-H) with the hope of creating a product with an improvement in mechanical strength. In this study, the crumb tyres were treated with waste organic sulfur compounds from a petroleum refining factory in order to modify their surface properties. Organic sulfur compounds with amphiphilic properties can enhance the hydrophilic properties of the rubber and increase the intermolecular interaction forces between rubber and C-S-H. In the present study, a colloid probe of C-S-H was prepared to measure these intermolecular interaction forces by utilizing an atomic force microscope. Experimental results showed that rubber particles treated with waste organic sulfur compounds became more hydrophilic. In addition, the intermolecular interaction forces increased with the adsorption of waste organic sulfur compounds on the surface of the rubber particles. The compressive, tensile and flexural strengths of concrete samples that included rubber particles treated with organic sulfur compound also increased significantly. PMID:19710121

  17. Preparation of magnetic rubber with high mechanical properties by latex compounding method

    NASA Astrophysics Data System (ADS)

    Hou, Chunlin; Gao, Li; Yu, Hailing; Sun, Youyi; Yao, Junru; Zhao, Guizhe; Liu, Yaqing

    2016-06-01

    the magnetic rubber based on Fe3O4 nanoparticles and nature rubber were prepared by latex compounding method, in which stable Fe3O4 aqueous solutions were mixed with natural rubber latex and additives. This process was fast, versatile, reliable, safe, environmentally friendly and inexpensive. What's more, it was found that the magnetic and mechanical properties of magnetic rubber increased together with increase in doping content of Fe3O4 nanoparticles. Especially, it was demonstrated that the tensile strength (25.0 Mpa) of magnetic rubber was improved to be 478.0% comparing to neat natural rubber (5.2 Mpa), which was 5 times higher than maximal value reported in previous work. At the same time, the magnetic rubber revealed better thermal stability and solvent resistance comparing to the neat natural rubber, too. The work dose not only provides a new way to environmentally friendly preparation of magnetic rubber at low temperature, but also improve the mechanical and magnetic properties of magnetic rubber applied in industry.

  18. The use of natural vs. man-modified wetlands by shorebirds and waterbirds

    USGS Publications Warehouse

    Erwin, R.M.; Coulter, M.; Cogswell, H.

    1986-01-01

    The loss of wetlands continues world-wide. The impact especially has been felt in coastal areas, but water management elsewhere has resulted in marked reductions of aquatic bird populations. Concern for wetland management led to the convocation of a symposium on waterbird and shorebird use of natural and man-modified wetlands in December 1985 at the first joint meeting of the Colonial Waterbird Group and the Pacific Seabird Group. Contributions discussed a wide cross-section of taxa, geographic area, wetland type, and level of approach. Coverage included North America, South America, and Europe.

  19. Improved rubber nanofillers

    SciTech Connect

    Boyle, T. J.

    2012-03-01

    During this task, Silane functionalized TiO2 and HK3Ti4O4(SiO4)3 were sent to Goodyear (GY) for testing. These materials were characterized based on their interaction with the model elastomer, squalene. The Van der Waals interactions and Hamaker Constants for ZnO particles in squalene and rubber materials were characterized and it was determined that a 10-20 nm spacing was necessary between primary filler particles to maintain a stable nanocomposite. Contact angle measurements on the ZnO and ZnO-silane materials indicated that the solvent should wet the particles, and solvophobic attractions should not be present. These studies showed that the surface modification with sulfosilane coupling agents was successful, and high levels of dispersion of the particles remained possible. Further, a novel surface charging phenomenon where negative surface charging is developed in the squalene environment was observed and corroborated by measurements of particle size and of the surface modified materials in squalene. This impacts the dispersion of the particles according to the traditional colloidal interpretation of electrostatic repulsive forces between particles. Additionally, thin nanocomposite fibers were developed using electrospinning. The size and shape of the oxides did not change during the electrospinning process, although the shape of the fiber and the distribution of the particles, particularly for ZnO, was not ideal. There was an obvious increase in elastic modulus and hardness from the addition of the oxides, but differentiating the oxides, and particularly the surfactants, was difficult. The A-1289 lead to the greatest dispersion of the filler particles, while the A-1589 and the NXT produced clustered particle aggregates. This agrees with previous study of these materials in low molecular weight squalene solvent studies reported earlier. The behavior of the nanoparticle ZnO and the microparticle silica is different as well, with the ZnO being contained within

  20. Application of asphalt rubber technology to recreational trails

    NASA Astrophysics Data System (ADS)

    Ni, Haifeng

    Crumb rubber aggregate was employed instead of stone/sand aggregate in asphalt pavement that was modified by fine rubber particles. Crumb rubber aggregate forms an elastic network in the asphalt, which improves the pavement's susceptibility to low-temperature cracking, and absorb more stress at the crack tips than the conventional asphalt pavement. Laboratory tests were conducted to evaluate the tension/compression performance of a blend of asphalt rubber with rubber aggregate (ARRA). An optimum design methodology was introduced by examining the effect of asphalt source, curing temperature, curing time, rubber content, aggregate size, compaction pressure, and the effect of certain additives. At ambient temperature, the ARRA with equal amount of binder and aggregate exhibits good mechanical properties. Vestenamer helps improve the pavement's strength, stiffness, and fracture resistance to low temperature cracking. It was demonstrated that such pavement meets the mechanical requirements for recreational trails, such as bicycle, or pedestrian trails. ARRA is a viscoelastic material which exhibits time-dependent and loading rate-dependent behavior. Temperature is a key issue to its response to an external load. Both temperature and rate dependences were investigated. A series of uniaxial compression relaxation tests on ARRA or Vestenamer modified ARRA were conducted at room temperature to study the time-dependent performance of ARRA. Schapery's theory was applied to characterize the nonlinear viscoelastic behavior of ARRA.

  1. Assessment of Genetically Modified Soybean in Relation to Natural Variation in the Soybean Seed Metabolome

    PubMed Central

    Clarke, Joseph D.; Alexander, Danny C.; Ward, Dennis P.; Ryals, John A.; Mitchell, Matthew W.; Wulff, Jacob E.; Guo, Lining

    2013-01-01

    Genetically modified (GM) crops currently constitute a significant and growing part of agriculture. An important aspect of GM crop adoption is to demonstrate safety and equivalence with respect to conventional crops. Untargeted metabolomics has the ability to profile diverse classes of metabolites and thus could be an adjunct for GM crop substantial equivalence assessment. To account for environmental effects and introgression of GM traits into diverse genetic backgrounds, we propose that the assessment for GM crop metabolic composition should be understood within the context of the natural variation for the crop. Using a non-targeted metabolomics platform, we profiled 169 metabolites and established their dynamic ranges from the seeds of 49 conventional soybean lines representing the current commercial genetic diversity. We further demonstrated that the metabolome of a GM line had no significant deviation from natural variation within the soybean metabolome, with the exception of changes in the targeted engineered pathway. PMID:24170158

  2. Approach to the synthesis of natural and modified oligonucleotides by the phosphotriester method using O-nucleophilic intramolecular catalysis.

    PubMed

    Efimov, Vladimir A; Molchanova, Natalia S; Chakhmakhcheva, Oksana G

    2007-01-01

    An approach to the solid phase synthesis of natural and modified oligonucleotides using phosphotriester technique has been developed. Particularly, this method allows the synthesis of ribo- and deoxyribo-oligonucleotides containing various 2'-modified mononucleotides as well as stereodefined nucleotide phosphorothioate analogues. PMID:18058542

  3. Restoring Natural Streamflow Variability by Modifying Multi-purpose Reservoir Operation

    NASA Astrophysics Data System (ADS)

    Shiau, J.

    2010-12-01

    Multi-purpose reservoirs typically provide benefits of water supply, hydroelectric power, and flood mitigation. Hydroelectric power generations generally do not consume water. However, temporal distribution of downstream flows is highly changed due to hydro-peaking effects. Associated with offstream diversion of water supplies for municipal, industrial, and agricultural requirements, natural streamflow characteristics of magnitude, duration, frequency, timing, and rate of change is significantly altered by multi-purpose reservoir operation. Natural flow regime has long been recognized a master factor for ecosystem health and biodiversity. Restoration of altered flow regime caused by multi-purpose reservoir operation is the main objective of this study. This study presents an optimization framework that modifying reservoir operation to seeking balance between human and environmental needs. The methodology presented in this study is applied to the Feitsui Reservoir, located in northern Taiwan, with main purpose of providing stable water-supply and auxiliary purpose of electricity generation and flood-peak attenuation. Reservoir releases are dominated by two decision variables, i.e., duration of water releases for each day and percentage of daily required releases within the duration. The current releasing policy of the Feitsui Reservoir releases water for water-supply and hydropower purposes during 8:00 am to 16:00 pm each day and no environmental flows releases. Although greater power generation is obtained by 100% releases distributed within 8-hour period, severe temporal alteration of streamflow is observed downstream of the reservoir. Modifying reservoir operation by relaxing these two variables and reserve certain ratio of streamflow as environmental flow to maintain downstream natural variability. The optimal reservoir releasing policy is searched by the multi-criterion decision making technique for considering reservoir performance in terms of shortage ratio

  4. Recycled rubber in cement composites

    SciTech Connect

    Raghavan, D.; Tratt, K.; Wool, R.P.

    1994-12-31

    Disposal of 200 million waste tires in the US each year has become a major problem. An environmentally sound innovative technology of recycling rubber in cement matrix was examined. Using silane coupling agent the rubber was bonded to the hydrating cement making a lighter composite, which absorbed more energy than ordinary Portland cement. The bonding information was obtained by peel strength analysis. SEM was used to understand the mode of fracture in pure cement paste, cement bonded rubber composite and rubber filled cement paste. It was found that cracks propagate through the rubber particle in rubber bonded cement composite while in unbonded rubber cement mix, the cracks propagate around the interface. The density and shrinkage measurements are also discussed.

  5. Rubber cement poisoning

    MedlinePlus

    ... common household glue. It is often used for arts and crafts projects. Breathing in large amounts of rubber cement fumes or swallowing any amount can be extremely dangerous, especially for a small child. This article is for information only. Do NOT ...

  6. Recycling rubber products sensibly

    SciTech Connect

    Fesus, E.M.; Eggleton, R.W.

    1991-03-01

    This article examines processes for surface treating ground rubber from tires and other sources to enhance its ability to chemically bond with an uncured elastomer matrix during vulcanization. The topics discussed are environmental effects, processing and physical and chemical properties, mesh size, compounding, loading study, mineral fillers, and applications.

  7. Recycled rubber, aggregate, and filler in asphalt paving mixtures. Transportation research record

    SciTech Connect

    1996-12-31

    ;Contents(Partial): Evaluation Systems for Crumb Rubber Modified Binders and Mixtures; Hot Mix Asphalt Rubber Applications in Virginia; Evaluation of Pyrolized Carbon Black from Scrap Tires as Additive in Hot Mix Asphalt; Use of Scrap Tire Chips in Asphaltic Membrane; Effects of Mineral Fillers on Properties of Stone Matrix Asphalt Mixtures; and Quantitative Analysis of Aggregate Based on Hough Transform.

  8. A computational study of adhesion between rubber and metal sulfides at rubber-brass interface

    NASA Astrophysics Data System (ADS)

    Ling, Chian Ye; Hirvi, Janne T.; Suvanto, Mika; Bazhenov, Andrey S.; Ajoviita, Tommi; Markkula, Katriina; Pakkanen, Tapani A.

    2015-05-01

    Computational study at level of density functional theory has been carried out in order to investigate the adhesion between rubber and brass plated steel cord, which has high importance in tire manufacturing. Adsorption of natural rubber based adsorbate models has been studied on zinc sulfide, ZnS(1 1 0), and copper sulfide, Cu2S(1 1 1) and CuS(0 0 1), surfaces as the corresponding phases are formed in adhesive interlayer during rubber vulcanization. Saturated hydrocarbons exhibited weak interactions, whereas unsaturated hydrocarbons and sulfur-containing adsorbates interacted with the metal atoms of sulfide surfaces more strongly. Sulfur-containing adsorbates interacted with ZnS(1 1 0) surface stronger than unsaturated hydrocarbons, whereras both Cu2S(1 1 1) and CuS(0 0 1) surfaces showed opposite adsorption preference as unsaturated hydrocarbons adsorbed stronger than sulfur-containing adsorbates. The different interaction strength order can play role in rubber-brass adhesion with different relative sulfide concentrations. Moreover, Cu2S(1 1 1) surface exhibits higher adsorption energies than CuS(0 0 1) surface, possibly indicating dominant role of Cu2S in the adhesion between rubber and brass.

  9. Effect of pretreatment of rubber material on its biodegradability by various rubber degrading bacteria.

    PubMed

    Berekaa, M M; Linos, A; Reichelt, R; Keller, U; Steinbüchel, A

    2000-03-15

    The effect of pretreatment of several cis-1,4-polyisoprene containing rubbers on their biodegradability was examined. Tests were carried out with six recently isolated and characterized rubber degrading bacteria belonging to the genera Gordonia (strains Kb2, Kd2 and VH2), Mycobacterium, Micromonospora and Pseudomonas. All strains were able to use natural rubber (NR) as well as NR latex gloves as sole carbon source. Extraction of NR latex gloves by organic solvents resulted in an enhancement of growth for three of the selected strains. On the other hand, growth of Gordonia sp. (strain Kb2 and Kd2), Mycobacterium fortuitum NF4 and Micromonospora aurantiaca W2b on synthetic cis-1,4-polyisoprene did only occur after removal of the antioxidants, that are usually added during manufacture to prevent aging of the materials. Detailed degradation studies performed with Gordonia sp. Kb2 revealed an enhanced mineralization of pretreated NR latex gloves and mineralization of purified natural rubber (NR), indicating the actual mineralization of cis-1,4-polyisoprene rubber constituent even after removal of non-rubber constituent that may act as co-metabolic substrate and support microbial growth. Further analysis by scanning electron microscopy (SEM) clearly demonstrated the enhanced colonization efficiency of these bacteria towards pretreated NR latex gloves. Colonization was additionally visualized by staining of overgrown NR latex gloves with Schiff's reagent, and the purple color produced in the area of degradation was an evidence for the accumulation of aldehydes containing oligomers. Further enhancement of latex gloves degradation could be achieved after successive replacement of mineral salts medium during cultivation. Thereby, a rapid disintegration of untreated NR latex gloves material was accomplished by Gordonia sp. strain VH2. PMID:10713421

  10. Guayule rubber: Cultivation and manufacture. (Latest citations from the Rubber and Plastics Rsearch Association database). Published Search

    SciTech Connect

    Not Available

    1994-06-01

    The bibliography contains citations concerning research and development of guayule as a natural rubber source. Cultivation methods and locations, physical and chemical properties, economic factors of cultivation through manufacture, production forecasts, effects of mixing with synthetic rubbers, and vulcanization are among the topics discussed. Industrial health hazards, performance in the world market, and applications are considered. (Contains a minimum of 206 citations and includes a subject term index and title list.)

  11. Effects of forests, roads and mistletoe on bird diversity in monoculture rubber plantations

    NASA Astrophysics Data System (ADS)

    Sreekar, Rachakonda; Huang, Guohualing; Yasuda, Mika; Quan, Rui-Chang; Goodale, Eben; Corlett, Richard T.; Tomlinson, Kyle W.

    2016-02-01

    Rising global demand for natural rubber is expanding monoculture rubber (Hevea brasilensis) at the expense of natural forests in the Old World tropics. Conversion of forests into rubber plantations has a devastating impact on biodiversity and we have yet to identify management strategies that can mitigate this. We determined the life-history traits that best predict bird species occurrence in rubber plantations in SW China and investigated the effects of surrounding forest cover and distance to roads on bird diversity. Mistletoes provide nectar and fruit resources in rubber so we examined mistletoe densities and the relationship with forest cover and rubber tree diameter. In rubber plantations, we recorded less than half of all bird species extant in the surrounding area. Birds with wider habitat breadths and low conservation value had a higher probability of occurrence. Species richness and diversity increased logarithmically with surrounding forest cover, but roads had little effect. Mistletoe density increased exponentially with rubber tree diameters, but was unrelated to forest cover. To maximize bird diversity in rubber-dominated landscapes it is therefore necessary to preserve as much forest as possible, construct roads through plantations and not forest, and retain some large rubber trees with mistletoes during crop rotations.

  12. Effects of forests, roads and mistletoe on bird diversity in monoculture rubber plantations.

    PubMed

    Sreekar, Rachakonda; Huang, Guohualing; Yasuda, Mika; Quan, Rui-Chang; Goodale, Eben; Corlett, Richard T; Tomlinson, Kyle W

    2016-01-01

    Rising global demand for natural rubber is expanding monoculture rubber (Hevea brasilensis) at the expense of natural forests in the Old World tropics. Conversion of forests into rubber plantations has a devastating impact on biodiversity and we have yet to identify management strategies that can mitigate this. We determined the life-history traits that best predict bird species occurrence in rubber plantations in SW China and investigated the effects of surrounding forest cover and distance to roads on bird diversity. Mistletoes provide nectar and fruit resources in rubber so we examined mistletoe densities and the relationship with forest cover and rubber tree diameter. In rubber plantations, we recorded less than half of all bird species extant in the surrounding area. Birds with wider habitat breadths and low conservation value had a higher probability of occurrence. Species richness and diversity increased logarithmically with surrounding forest cover, but roads had little effect. Mistletoe density increased exponentially with rubber tree diameters, but was unrelated to forest cover. To maximize bird diversity in rubber-dominated landscapes it is therefore necessary to preserve as much forest as possible, construct roads through plantations and not forest, and retain some large rubber trees with mistletoes during crop rotations. PMID:26903032

  13. Effects of forests, roads and mistletoe on bird diversity in monoculture rubber plantations

    PubMed Central

    Sreekar, Rachakonda; Huang, Guohualing; Yasuda, Mika; Quan, Rui-Chang; Goodale, Eben; Corlett, Richard T.; Tomlinson, Kyle W.

    2016-01-01

    Rising global demand for natural rubber is expanding monoculture rubber (Hevea brasilensis) at the expense of natural forests in the Old World tropics. Conversion of forests into rubber plantations has a devastating impact on biodiversity and we have yet to identify management strategies that can mitigate this. We determined the life-history traits that best predict bird species occurrence in rubber plantations in SW China and investigated the effects of surrounding forest cover and distance to roads on bird diversity. Mistletoes provide nectar and fruit resources in rubber so we examined mistletoe densities and the relationship with forest cover and rubber tree diameter. In rubber plantations, we recorded less than half of all bird species extant in the surrounding area. Birds with wider habitat breadths and low conservation value had a higher probability of occurrence. Species richness and diversity increased logarithmically with surrounding forest cover, but roads had little effect. Mistletoe density increased exponentially with rubber tree diameters, but was unrelated to forest cover. To maximize bird diversity in rubber-dominated landscapes it is therefore necessary to preserve as much forest as possible, construct roads through plantations and not forest, and retain some large rubber trees with mistletoes during crop rotations. PMID:26903032

  14. Physicochemical, thermal and computational study of the encapsulation of rumenic acid by natural and modified cyclodextrins.

    PubMed

    Matencio, Adrián; Hernández-Gil, Carlos Javier García; García-Carmona, Francisco; López-Nicolás, José Manuel

    2017-02-01

    In this work the aggregation behavior of Rumenic acid (RA) is presented for the first time. The results point to a c.m.c. of 35μM at pH 8 and 25°C. This behavior can be modified by introducing CDs into the system to encapsulate the RA. The encapsulation process presented a 1:1 stoichiometry in all the cases studied but the complexation constants were strongly dependent on the type of CDs used, the pH and temperature. Firstly, the effect of the type of CD on the encapsulation process was studied. Among the natural and modified CDs analyzed HPβCD was the best for encapsulating RA. The pKa determined for RA was 4.31. The KF showed different behavior below and above 25°C due to changes in the stoichiometry. Finally, molecular docking calculations provided further insights into how the different interactions influence the complexation constant. PMID:27596422

  15. Radiation-modified natural zeolites for cleaning liquid nuclear waste (irradiation against radioactivity)

    PubMed Central

    Yeritsyan, Hrant; Sahakyan, Aram; Harutyunyan, Vachagan; Nikoghosyan, Sergey; Hakhverdyan, Eleonora; Grigoryan, Norair; Hovhannisyan, Aghasi; Atoyan, Vovik; Keheyan, Yeghis; Rhodes, Christopher

    2013-01-01

    There have been comparatively few investigations reported of radiation effects in zeolites, although it is known that these materials may be modified substantially by exposure to ionizing radiation. Thus, by exposure to γ-rays or high-energy particles, the charge states of atoms may be changed so to create, and accumulate, lattice point defects, and to form structurally disordered regions. Such a technique may permit the creation, in a controlled fashion, of additionally useful properties of the material while preserving its essential stoichiometry and structure. Accordingly, we present an application, in which the cation-exchange capacity of a natural zeolite (clinoptilolite) is substantially enhanced, for the treatment/decontamination of water contaminated with radionuclides e.g. 134Cs, 137Cs and 90Sr, by its exposure to high-energy (8 MeV) electrons, and to different total doses. PMID:24132177

  16. Radiation-modified natural zeolites for cleaning liquid nuclear waste (irradiation against radioactivity)

    NASA Astrophysics Data System (ADS)

    Yeritsyan, Hrant; Sahakyan, Aram; Harutyunyan, Vachagan; Nikoghosyan, Sergey; Hakhverdyan, Eleonora; Grigoryan, Norair; Hovhannisyan, Aghasi; Atoyan, Vovik; Keheyan, Yeghis; Rhodes, Christopher

    2013-10-01

    There have been comparatively few investigations reported of radiation effects in zeolites, although it is known that these materials may be modified substantially by exposure to ionizing radiation. Thus, by exposure to γ-rays or high-energy particles, the charge states of atoms may be changed so to create, and accumulate, lattice point defects, and to form structurally disordered regions. Such a technique may permit the creation, in a controlled fashion, of additionally useful properties of the material while preserving its essential stoichiometry and structure. Accordingly, we present an application, in which the cation-exchange capacity of a natural zeolite (clinoptilolite) is substantially enhanced, for the treatment/decontamination of water contaminated with radionuclides e.g. 134Cs, 137Cs and 90Sr, by its exposure to high-energy (8 MeV) electrons, and to different total doses.

  17. Radiation-modified natural zeolites for cleaning liquid nuclear waste (irradiation against radioactivity).

    PubMed

    Yeritsyan, Hrant; Sahakyan, Aram; Harutyunyan, Vachagan; Nikoghosyan, Sergey; Hakhverdyan, Eleonora; Grigoryan, Norair; Hovhannisyan, Aghasi; Atoyan, Vovik; Keheyan, Yeghis; Rhodes, Christopher

    2013-01-01

    There have been comparatively few investigations reported of radiation effects in zeolites, although it is known that these materials may be modified substantially by exposure to ionizing radiation. Thus, by exposure to γ-rays or high-energy particles, the charge states of atoms may be changed so to create, and accumulate, lattice point defects, and to form structurally disordered regions. Such a technique may permit the creation, in a controlled fashion, of additionally useful properties of the material while preserving its essential stoichiometry and structure. Accordingly, we present an application, in which the cation-exchange capacity of a natural zeolite (clinoptilolite) is substantially enhanced, for the treatment/decontamination of water contaminated with radionuclides e.g. (134)Cs, (137)Cs and (90)Sr, by its exposure to high-energy (8 MeV) electrons, and to different total doses. PMID:24132177

  18. Surface modified natural zeolite as a carrier for sustained diclofenac release: A preliminary feasibility study.

    PubMed

    de Gennaro, Bruno; Catalanotti, Lilia; Cappelletti, Piergiulio; Langella, Alessio; Mercurio, Mariano; Serri, Carla; Biondi, Marco; Mayol, Laura

    2015-06-01

    In view of zeolite potentiality as a carrier for sustained drug release, a clinoptilolite-rich rock from California (CLI_CA) was superficially modified with cetylpyridinium chloride and loaded with diclofenac sodium (DS). The obtained surface modified natural zeolites (SMNZ) were characterized by confocal scanning laser microscopy (CLSM), powder X-ray diffraction (XRPD) and laser light scattering (LS). Their flowability properties, drug adsorption and in vitro release kinetics in simulated intestinal fluid (SIF) were also investigated. CLI_CA is a Na- and K-rich clinoptilolite with a cationic exchange ability that fits well with its zeolite content (clinoptilolite=80 wt%); the external cationic exchange capacity is independent of the cationic surfactant used. LS and CLSM analyses have shown a wide distribution of volume diameters of SMNZ particles that, along with their irregular shape, make them cohesive with scarce flow properties. CLSM observation has revealed the localization of different molecules in/on SMNZ by virtue of their chemical nature. In particular, cationic and polar probes prevalently localize in SMNZ bulk, whereas anionic probes preferentially arrange themselves on SMNZ surface and the loading of a nonpolar molecule in/on SMNZ is discouraged. The adsorption rate of DS onto SMNZ was shown by different kinetic models highlighting the fact that DS adsorption is a pseudo-second order reaction and that the diffusion through the boundary layer is the rate-controlling step of the process. DS release in an ionic medium, such as SIF, can be sustained for about 5h through a mechanism prevalently governed by anionic exchange with a rapid final phase. PMID:25919666

  19. Crumb rubber feasibility report

    SciTech Connect

    1985-11-01

    The Cumberland County supply region generates approximately 58,000 tons of scrap tires each year, equivalent to 45,000 tons of rubber after processing. Approximately 8,000 tons per year are in concentrated locations and can be easily collected. The costs of collection for the remainder vary significantly. Given current markets, economically feasible processes (ambient technology) can reprocess approximately 65 to 75 percent of the 37,000 tons into a marketable product. A processing plant sized for this supply would process 120 tons per day, a viable plant by industry standards. The end uses for whole tires constitute a negligible market, aside from the retreader market. Crumbed rubber is the major development efforts, there are potentially large opportunities in North Carolina.

  20. Elastic instabilities in rubber

    NASA Astrophysics Data System (ADS)

    Gent, Alan

    2009-03-01

    Materials that undergo large elastic deformations can exhibit novel instabilities. Several examples are described: development of an aneurysm on inflating a rubber tube; non-uniform stretching on inflating a spherical balloon; formation of internal cracks in rubber blocks at a critical level of triaxial tension or when supersaturated with a dissolved gas; surface wrinkling of a block at a critical amount of compression; debonding or fracture of constrained films on swelling, and formation of ``knots'' on twisting stretched cylindrical rods. These various deformations are analyzed in terms of a simple strain energy function, using Rivlin's theory of large elastic deformations, and the results are compared with experimental measurements of the onset of unstable states. Such comparisons provide new tests of Rivlin's theory and, at least in principle, critical tests of proposed strain energy functions for rubber. Moreover the onset of highly non-uniform deformations has serious implications for the fatigue life and fracture resistance of rubber components. [4pt] References: [0pt] R. S. Rivlin, Philos. Trans. Roy. Soc. Lond. Ser. A241 (1948) 379--397. [0pt] A. Mallock, Proc. Roy. Soc. Lond. 49 (1890--1891) 458--463. [0pt] M. A. Biot, ``Mechanics of Incremental Deformations'', Wiley, New York, 1965. [0pt] A. N. Gent and P. B. Lindley, Proc. Roy. Soc. Lond. A 249 (1958) 195--205. [0pt] A. N. Gent, W. J. Hung and M. F. Tse, Rubb. Chem. Technol. 74 (2001) 89--99. [0pt] A. N. Gent, Internatl. J. Non-Linear Mech. 40 (2005) 165--175.

  1. A review on using crumb rubber in reinforcement of asphalt pavement.

    PubMed

    Mashaan, Nuha Salim; Ali, Asim Hassan; Karim, Mohamed Rehan; Abdelaziz, Mahrez

    2014-01-01

    An immense problem affecting environmental pollution is the increase of waste tyre vehicles. In an attempt to decrease the magnitude of this issue, crumb rubber modifier (CRM) obtained from waste tyre rubber has gained interest in asphalt reinforcement. The use of crumb rubber in the reinforcement of asphalt is considered as a smart solution for sustainable development by reusing waste materials, and it is believed that crumb rubber modifier (CRM) could be an alternative polymer material in improving hot mix asphalt performance properties. In this paper, a critical review on the use of crumb rubber in reinforcement of asphalt pavement will be presented and discussed. It will also include a review on the effects of CRM on the stiffness, rutting, and fatigue resistance of road pavement construction. PMID:24688369

  2. A Review on Using Crumb Rubber in Reinforcement of Asphalt Pavement

    PubMed Central

    Mashaan, Nuha Salim; Ali, Asim Hassan; Karim, Mohamed Rehan; Abdelaziz, Mahrez

    2014-01-01

    An immense problem affecting environmental pollution is the increase of waste tyre vehicles. In an attempt to decrease the magnitude of this issue, crumb rubber modifier (CRM) obtained from waste tyre rubber has gained interest in asphalt reinforcement. The use of crumb rubber in the reinforcement of asphalt is considered as a smart solution for sustainable development by reusing waste materials, and it is believed that crumb rubber modifier (CRM) could be an alternative polymer material in improving hot mix asphalt performance properties. In this paper, a critical review on the use of crumb rubber in reinforcement of asphalt pavement will be presented and discussed. It will also include a review on the effects of CRM on the stiffness, rutting, and fatigue resistance of road pavement construction. PMID:24688369

  3. Pushing the Limits: The Pattern and Dynamics of Rubber Monoculture Expansion in Xishuangbanna, SW China

    PubMed Central

    Ahrends, Antje; Beckschäfer, Philip; Kleinn, Christoph; Ranjitkar, Sailesh

    2016-01-01

    The rapidly growing car industry in China has led to an equally rapid expansion of monoculture rubber in many regions of South East Asia. Xishuangbanna, the second largest rubber planting area in China, located in the Indo-Burma biodiversity hotspot, supplies about 37% of the domestic natural rubber production. There, high income possibilities from rubber drive a dramatic expansion of monoculture plantations which poses a threat to natural forests. For the first time we mapped rubber plantations in and outside protected areas and their net present value for the years 1988, 2002 (Landsat, 30 m resolution) and 2010 (RapidEye, 5 m resolution). The purpose of our study was to better understand the pattern and dynamics of the expansion of rubber plantations in Xishuangbanna, as well as its economic prospects and conservation impacts. We found that 1) the area of rubber plantations was 4.5% of the total area of Xishuangbanna in 1988, 9.9% in 2002, and 22.2% in 2010; 2) rubber monoculture expanded to higher elevations and onto steeper slopes between 1988 and 2010; 3) the proportion of rubber plantations with medium economic potential dropped from 57% between 1988 and 2002 to 47% in 2010, while the proportion of plantations with lower economic potential had increased from 30% to 40%; and 4) nearly 10% of the total area of nature reserves within Xishuangbanna has been converted to rubber monoculture by 2010. On the basis of our findings, we conclude that the rapid expansion of rubber plantations into higher elevations, steeper terrain, and into nature reserves (where most of the remaining forests of Xishuangbanna are located) poses a serious threat to biodiversity and environmental services while not producing the expected economic returns. Therefore, it is essential that local governments develop long-term land use strategies for balancing economic benefits with environmental sustainability, as well as for assisting farmers with the selection of land suitable for rubber

  4. Pushing the Limits: The Pattern and Dynamics of Rubber Monoculture Expansion in Xishuangbanna, SW China.

    PubMed

    Chen, Huafang; Yi, Zhuang-Fang; Schmidt-Vogt, Dietrich; Ahrends, Antje; Beckschäfer, Philip; Kleinn, Christoph; Ranjitkar, Sailesh; Xu, Jianchu

    2016-01-01

    The rapidly growing car industry in China has led to an equally rapid expansion of monoculture rubber in many regions of South East Asia. Xishuangbanna, the second largest rubber planting area in China, located in the Indo-Burma biodiversity hotspot, supplies about 37% of the domestic natural rubber production. There, high income possibilities from rubber drive a dramatic expansion of monoculture plantations which poses a threat to natural forests. For the first time we mapped rubber plantations in and outside protected areas and their net present value for the years 1988, 2002 (Landsat, 30 m resolution) and 2010 (RapidEye, 5 m resolution). The purpose of our study was to better understand the pattern and dynamics of the expansion of rubber plantations in Xishuangbanna, as well as its economic prospects and conservation impacts. We found that 1) the area of rubber plantations was 4.5% of the total area of Xishuangbanna in 1988, 9.9% in 2002, and 22.2% in 2010; 2) rubber monoculture expanded to higher elevations and onto steeper slopes between 1988 and 2010; 3) the proportion of rubber plantations with medium economic potential dropped from 57% between 1988 and 2002 to 47% in 2010, while the proportion of plantations with lower economic potential had increased from 30% to 40%; and 4) nearly 10% of the total area of nature reserves within Xishuangbanna has been converted to rubber monoculture by 2010. On the basis of our findings, we conclude that the rapid expansion of rubber plantations into higher elevations, steeper terrain, and into nature reserves (where most of the remaining forests of Xishuangbanna are located) poses a serious threat to biodiversity and environmental services while not producing the expected economic returns. Therefore, it is essential that local governments develop long-term land use strategies for balancing economic benefits with environmental sustainability, as well as for assisting farmers with the selection of land suitable for rubber

  5. Theory of powdery rubber wear.

    PubMed

    Persson, B N J

    2009-12-01

    Rubber wear typically involves the removal of small rubber particles from the rubber surface. On surfaces with not too sharp roughness, e.g. most road surfaces, this involves (slow) crack propagation. In this paper I shall present a theory of mild rubber wear. I shall derive the distribution of wear particle sizes Φ(D), which is in excellent agreement with experiment. I shall also show that the calculated wear rate is consistent with experimental data for tire tread block wear. PMID:21832508

  6. Sorption of uranium(6+) and neptunium(5+) by surfactant-modified natural zeolites

    SciTech Connect

    Prikryl, J.D.; Pabalan, R.T.

    1999-07-01

    Experiments were conducted to determine the ability of surfactant-modification to enhance the ability of natural zeolites to sorb U(6+) and Np(5+). Natural zeolite material, comprised mainly of clinoptilolite and treated with the cationic surfactant hexadecyltrimethylammonium-bromide (HDTMA), was reacted with U(6+) and Np(5+) solutions open to the atmosphere and having a range of radionuclide concentration, pH, and NaCl concentration. The results indicate surfactant-modification of the zeolite enhances its ability to sorb U(6+), particularly at pHs greater than six where U(6+) sorption on unmodified zeolite is typically low due to formation of anionic U(6+) aqueous carbonate complexes. In contrast, there is little enhancement of Np(5+) sorption onto surfactant-modified zeolite. The presence of chloride anions in solution makes surfactant-modification less effective. The enhanced sorption of U(6+) is interpreted to be due to anion exchange with counterions on the external portion of a surfactant bilayer or admicelles.

  7. Structure properties relationship in electrospun thermoset butyl rubber

    NASA Astrophysics Data System (ADS)

    Viriyabanthorn, Nantiya

    Development of breathable elastomeric membranes based upon butyl rubber (IIR) compounds was investigated. These semi-permeable membranes were produced by electrospinning the compounded butyl rubber under appropriate conditions. They were designed to be selectively permeable. Specifically, these elastomeric membranes allowed moisture vapor transport, while maintaining a barrier against liquid water. Additionally, the conductive nature of carbon black in the compounds was shown to allow greater control over membrane thickness than generally observed in electrospun fabrics. Data were presented to show that the excellent chemical resistance of butyl rubber to organic solvents and toxic agents was maintained despite the porous nature of the membranes. Air flow resistance could also be adjusted as functions of processing conditions which related to fiber diameter and porosity of the membrane. Mechanical properties, in addition to various transport properties, are compared to a butyl rubber baseline. The moisture vapor transport properties are compared to expanded PTFE films. The results demonstrate the effectiveness of thermoset elastomeric membranes for producing flexible, selectively permeable barriers. Moreover, It also shows the capability to produce nonwoven materials for applications requiring high elongation (stretch) and porosity. In most elastomer formulations, carbon black is used as filler because of its reinforcing properties. The addition of carbon was also found to be important in the electrospinning of butyl rubber. Carbon black typically results in improved mechanical properties for rubber compounds, however, its conductive properties can also play a role in the resulting fiber structure during the electrospinning process. Carbon black loadings were varied from 0, 25, 50, and 75 parts per hundred rubber (phr). Increased carbon black loading resulted in a larger process window and reduced density and bead formation. Tensile modulus (corrected for changes

  8. Study on Nanomorphology of High-Structure Carbon Black and its Bound Rubber by Afm

    NASA Astrophysics Data System (ADS)

    Chen, Jian; Jin, Yongzhong; Zhang, Jingyu; Wu, Yafeng; Meng, Chuncai

    2012-02-01

    Bound rubber in carbon black (CB) filled rubber (natural rubber (NR) and styrene-butadiene rubber (SBS)) was prepared by the solvent method. The nanomorphology of CB and rubber/CB soluble rubber was observed by atomic force microscope. The results show that high-structure CB DZ13 has a "grape cluster" structure which consists of many original particles with the grain size of about 30-50 nm. Graphitizing process of CB decreases the amount of bound rubber. The NR/DZ13 soluble rubber with island-rim structure has been obtained, where the islands are DZ13 particles and the rims around the islands are occupied by NR film. But when the graphitized DZ13 particles were used as fillers of rubber, we have only observed that some graphitized DZ13 particles were deposited on the surface of the globular-like NR molecular chains, instead of the spreading of NR molecular chains along the surface of DZ13 particles, indicating that graphitized DZ13 has lower chemical activity than ungraphitized DZ13. Especially, we have already observed an interesting unusual bound rubber phenomenon, the blocked "bracelet" structure with the diameter of about 600 nm in which CB particles were blocked in ring-shaped SBS monomer.

  9. Investigations of the mixing behaviour of pin-type rubber extruders

    NASA Astrophysics Data System (ADS)

    Schöppner, Volker; Schadomsky, Michael; Hopmann, Christian; Lemke, Florian

    2016-03-01

    This paper deals with investigations of the mixing behaviour of rubber extruders. The requirement to obtain a high-quality elastomer product is a thermally and materially homogenous rubber mixture. Because of the highly viscous and multicomponent nature of rubber mixture, extruders require a thoroughly distributive and dispersive mixing behaviour. The current state of the art is the pin-type rubber extruder with cylindrical pins which extend radially into the screw channel, causing a constant deformation and reorientation of the rubber melt. As mixing is of crucial importance, the mixing behaviour of pin-type rubber extruders is analysed with the goal of optimising it. The starting point of the optimisation is the current cylindrical pins. Over the course of the investigation, new pin designs and geometrical arrangements are investigated.

  10. Rubber composition compatible with hydrazine

    NASA Technical Reports Server (NTRS)

    Repar, J.

    1973-01-01

    Formulation improves compatibility of butyl rubbers with hydrazine while reducing permeation to low levels necessary for prolonged storage in space. This is accomplished by replacing carbon-black filler with inert materials such as hydrated silica or clay. Pressure increases suggest that hydrazine is decomposed only slightly by new type of rubber.

  11. Recycled rubber roads

    SciTech Connect

    Not Available

    1989-02-01

    The paper describes several innovative approaches for recycling old tires in the construction of roads. In one, 18 inches of shredded tire chips (2 X 2 inches) were used on top of 6-8 inches of small stone to construct a road across a sanitary landfill. No compacting or linders were needed. In another application, sidewall mats linked together with steel strapping were used as a sub-base for a road across a swampy area. A third application uses 1/2 inch bits of groundup rubber tires as a replacement for aggregate in an asphalt road base.

  12. Mechanistic study of the rubber-brass adhesion interphase

    NASA Astrophysics Data System (ADS)

    Ashirgade, Akshay

    Brass-plated steel tire cords form an essential strengthening component of a radial automobile tire. Adhesion between rubber compound and brass-plated steel tire cord is crucial in governing the overall performance of tires. The rubber-brass interfacial adhesion is influenced by the chemical composition and thickness of the interfacial layer. It has been shown that the interfacial layer consists mainly of sulfides and oxides of copper and zinc. This thesis discusses the effect of changes in the chemical composition and the structure of the interfacial layers due to addition of adhesion promoter resins. Grazing incidence X-Ray Diffraction (GIXRD) experiments were run on sulfidized polished brass coupons previously bonded to six experimental rubber compounds. It was confirmed that heat and humidity conditions lead to physical and chemical changes of the rubber-steel tire cord interfacial layer, closely related to the degree of rubber-brass adhesion. Morphological transformation of the interfacial layer led to loss of adhesion after aging. The adhesion promoter resins inhibit unfavorable morphological changes in the interfacial layer thus stabilizing it during aging and prolonging failure. Tire cord adhesion tests illustrated that the one-component resins improved adhesion after aging using a rubber compound with lower cobalt loading. Based on the acquired diffraction profiles, these resins were also found to impede crystallization of the sulfide layer after aging leading to improved adhesion. Secondary Ion Mass Spectrometry (SIMS) depth profiles, SEM micrographs and AFM images strongly corroborated the findings from GIXRD. FTIR was utilized in a novel way to understand the degradation mechanism due to aging. A model for rubber and interfacial layer degradation is proposed to illustrate the effect of aging and the one-component resins. This interfacial analysis adds valuable new information to our understanding of the complex nature of the rubber-brass bonding

  13. Diamondoid-functionalized gold nanogaps as sensors for natural, mutated, and epigenetically modified DNA nucleotides

    NASA Astrophysics Data System (ADS)

    Sivaraman, Ganesh; Amorim, Rodrigo G.; Scheicher, Ralph H.; Fyta, Maria

    2016-05-01

    Modified tiny hydrogen-terminated diamond structures, known as diamondoids, show a high efficiency in sensing DNA molecules. These diamond cages, as recently proposed, could offer functionalization possibilities for gold junction electrodes. In this investigation, we report on diamondoid-functionalized electrodes, showing that such a device would have a high potential in sensing and sequencing DNA. The smallest diamondoid including an amine modification was chosen for the functionalization. Here, we report on the quantum tunneling signals across diamondoid-functionalized Au(111) electrodes. Our work is based on quantum-transport calculations and predicts the expected signals arising from different DNA units within the break junctions. Different gating voltages are proposed in order to tune the sensitivity of the functionalized electrodes with respect to specific nucleotides. The relation of this sensitivity to the coupling or decoupling of the electrodes is discussed. Our results also shed light on the sensing capability of such a device in distinguishing the DNA nucleotides, in their natural and mutated forms.

  14. Diamondoid-functionalized gold nanogaps as sensors for natural, mutated, and epigenetically modified DNA nucleotides.

    PubMed

    Sivaraman, Ganesh; Amorim, Rodrigo G; Scheicher, Ralph H; Fyta, Maria

    2016-05-21

    Modified tiny hydrogen-terminated diamond structures, known as diamondoids, show a high efficiency in sensing DNA molecules. These diamond cages, as recently proposed, could offer functionalization possibilities for gold junction electrodes. In this investigation, we report on diamondoid-functionalized electrodes, showing that such a device would have a high potential in sensing and sequencing DNA. The smallest diamondoid including an amine modification was chosen for the functionalization. Here, we report on the quantum tunneling signals across diamondoid-functionalized Au(111) electrodes. Our work is based on quantum-transport calculations and predicts the expected signals arising from different DNA units within the break junctions. Different gating voltages are proposed in order to tune the sensitivity of the functionalized electrodes with respect to specific nucleotides. The relation of this sensitivity to the coupling or decoupling of the electrodes is discussed. Our results also shed light on the sensing capability of such a device in distinguishing the DNA nucleotides, in their natural and mutated forms. PMID:27121677

  15. Modified procedure for labelling target cells in a europium release assay of natural killer cell activity.

    PubMed

    Pacifici, R; Di Carlo, S; Bacosi, A; Altieri, I; Pichini, S; Zuccaro, P

    1993-05-01

    Lanthanide europium chelated to diethylenetriaminopentaacetate (EuDTPA) can be used to label target cells such as tumor cells and lymphocytes (Blomberg et al., 1986a,b; Granberg et al., 1988). This procedure has permitted the development of new non-radioactive methods for the detection of target cell cytolysis by natural killer (NK) cells (Blomberg et al., 1986a,b), cytotoxic T lymphocytes (CTL) (Granberg et al., 1988) or complement-mediated cytolysis (Cui et al., 1992). However, we had no success with this method because of a lack of comparability between human NK cell activity simultaneously measured by a classical 51Cr release assay (Seaman et al., 1981) and EuDTPA release assay (Blomberg et al., 1986a). Furthermore, cell division and cell viability were significantly impaired by the suggested concentrations of EuCl3. In this paper, we present a modified non-cytotoxic method for target cell labelling with EuDTPA while cells are growing in culture medium. PMID:8486925

  16. Robotically enhanced rubber hand illusion.

    PubMed

    Arata, Jumpei; Hattori, Masashi; Ichikawa, Shohei; Sakaguchi, Masamichi

    2014-01-01

    The rubber hand illusion is a well-known multisensory illusion. In brief, watching a rubber hand being stroked by a paintbrush while one's own unseen hand is synchronously stroked causes the rubber hand to be attributed to one's own body and to "feel like it's my hand." The rubber hand illusion is thought to be triggered by the synchronized tactile stimulation of both the subject's hand and the fake hand. To extend the conventional rubber hand illusion, we introduce robotic technology in the form of a master-slave telemanipulator. The developed one degree-of-freedom master-slave system consists of an exoskeleton master equipped with an optical encoder that is worn on the subject's index finger and a motor-actuated index finger on the rubber hand, which allows the subject to perform unilateral telemanipulation. The moving rubber hand illusion has been studied by several researchers in the past with mechanically connected rigs between the subject's body and the fake limb. The robotic instruments let us investigate the moving rubber hand illusion with less constraints, thus behaving closer to the classic rubber hand illusion. In addition, the temporal delay between the body and the fake limb can be precisely manipulated. The experimental results revealed that the robotic instruments significantly enhance the rubber hand illusion. The time delay is significantly correlated with the effect of the multisensory illusion, and the effect significantly decreased at time delays over 100 ms. These findings can potentially contribute to the investigations of neural mechanisms in the field of neuroscience and of master-slave systems in the field of robotics. PMID:25532152

  17. Molecular Motion in Polymers: Mechanical Behavior of Polymers Near the Glass-Rubber Transition Temperature.

    ERIC Educational Resources Information Center

    Sperling, L. H.

    1982-01-01

    The temperature at which the onset of coordinated segmental motion begins is called the glass-rubber transition temperature (Tg). Natural rubber at room temperature is a good example of a material above its Tg. Describes an experiment examining the response of a typical polymer to temperature variations above and below Tg. (Author/JN)

  18. Ficus elastica-The Indian rubber tree-an underutilized promising multi-use species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ficus elastica known as the Indian rubber tree has a white, milky latex that is a source of natural rubber was analyzed for its phytochemicals as an intermediate energy source. The tree produces a high quantity of protein and oil (24.5 and 6.1% respectively). The polyphenol content was 4.2%, and hyd...

  19. Ribosomally synthesized and post-translationally modified peptide natural products: overview and recommendations for a universal nomenclature

    PubMed Central

    Arnison, Paul G.; Bibb, Mervyn J.; Bierbaum, Gabriele; Bowers, Albert A.; Bugni, Tim S.; Bulaj, Grzegorz; Camarero, Julio A.; Campopiano, Dominic J.; Challis, Gregory L.; Clardy, Jon; Cotter, Paul D.; Craik, David J.; Dawson, Michael; Dittmann, Elke; Donadio, Stefano; Dorrestein, Pieter C.; Entian, Karl-Dieter; Fischbach, Michael A.; Garavelli, John S.; Göransson, Ulf; Gruber, Christian W.; Haft, Daniel H.; Hemscheidt, Thomas K.; Hertweck, Christian; Hill, Colin; Horswill, Alexander R.; Jaspars, Marcel; Kelly, Wendy L.; Klinman, Judith P.; Kuipers, Oscar P.; Link, A. James; Liu, Wen; Marahiel, Mohamed A.; Mitchell, Douglas A.; Moll, Gert N.; Moore, Bradley S.; Müller, Rolf; Nair, Satish K.; Nes, Ingolf F.; Norris, Gillian E.; Olivera, Baldomero M.; Onaka, Hiroyasu; Patchett, Mark L.; Piel, Joern; Reaney, Martin J. T.; Rebuffat, Sylvie; Ross, R. Paul; Sahl, Hans-Georg; Schmidt, Eric W.; Selsted, Michael E.; Severinov, Konstantin; Shen, Ben; Sivonen, Kaarina; Smith, Leif; Stein, Torsten; Süssmuth, Roderich D.; Tagg, John R.; Tang, Gong-Li; Truman, Andrew W.; Vederas, John C.; Walsh, Christopher T.; Walton, Jonathan D.; Wenzel, Silke C.; Willey, Joanne M.; van der Donk, Wilfred A.

    2014-01-01

    This review presents recommended nomenclature for the biosynthesis of ribosomally synthesized and post-translationally modified peptides (RiPPs), a rapidly growing class of natural products. The current knowledge regarding the biosynthesis of the >20 distinct compound classes is also reviewed, and commonalities are discussed. PMID:23165928

  20. Genetic modifiers of ambulation in the cooperative international Neuromuscular research group Duchenne natural history study

    PubMed Central

    Bello, Luca; Kesari, Akanchha; Gordish-Dressman, Heather; Cnaan, Avital; Morgenroth, Lauren P; Punetha, Jaya; Duong, Tina; Henricson, Erik K; Pegoraro, Elena; McDonald, Craig M; Hoffman, Eric P

    2015-01-01

    Objective We studied the effects of LTBP4 and SPP1 polymorphisms on age at loss of ambulation (LoA) in a multiethnic Duchenne muscular dystrophy (DMD) cohort. Methods We genotyped SPP1 rs28357094 and LTBP4 haplotype in 283 of 340 participants in the Cooperative International Neuromuscular Research Group Duchenne Natural History Study (CINRG-DNHS). Median ages at LoA were compared by Kaplan–Meier analysis and log-rank test. We controlled polymorphism analyses for concurrent effects of glucocorticoid corticosteroid (GC) treatment (time-varying Cox regression) and for population stratification (multidimensional scaling of genome-wide markers). Results Hispanic and South Asian participants (n = 18, 41) lost ambulation 2.7 and 2 years earlier than Caucasian subjects (p = 0.003, <0.001). The TG/GG genotype at SPP1 rs28357094 was associated to 1.2-year-earlier median LoA (p = 0.048). This difference was greater (1.9 years, p = 0.038) in GC-treated participants, whereas no difference was observed in untreated subjects. Cox regression confirmed a significant effect of SPP1 genotype in GC-treated participants (hazard ratio = 1.61, p = 0.016). LTBP4 genotype showed a direction of association with age at LoA as previously reported, but it was not statistically significant. After controlling for population stratification, we confirmed a strong effect of LTBP4 genotype in Caucasians (2.4 years, p = 0.024). Median age at LoA with the protective LTBP4 genotype in this cohort was 15.0 years, 16.0 for those who were treated with GC. Interpretation SPP1 rs28357094 acts as a pharmacodynamic biomarker of GC response, and LTBP4 haplotype modifies age at LoA in the CINRG-DNHS cohort. Adjustment for GC treatment and population stratification appears crucial in assessing genetic modifiers in DMD. PMID:25641372

  1. Chlorinolysis reclaims rubber of waste tires

    NASA Technical Reports Server (NTRS)

    Dufresne, E. R.; Tervet, J. H.; Hull, G. G.

    1981-01-01

    Process reclaims rubber and reduces sulfur content by using chlorine gas to oxidize sulfur bonds in preference to other bonds. Rubber does not have poor hysteresis and abrasion resistance like conventionally reclaimed rubber and is suitable for premium radial tires. Chlorinated rubber is less susceptible to swelling by oils and may be used as paint ingredient.

  2. Recycling, production and use of reprocessed rubbers

    SciTech Connect

    Klingensmith, B. )

    1991-03-01

    This article examines the various methods used to produce recycled rubber and to compare their characteristics and application. The topics discussed include reclaiming by chemical digestion, devulcanization by the severing of sulfur bonds, ambient temperature and cryogenically ground rubber, processing and mixing of ground rubber, and properties of reclaimed rubbers by reclamation method.

  3. Inhibition of deterioration of rubbers by hydroaromatics

    SciTech Connect

    Kubo, Junichi )

    1993-03-01

    Based on the results obtained from previous works, which concluded that hydrogen donating hydroaromatics can be available as radical scavengers in inhibiting the deterioration of hydrocarbon products at lower oxygen partial pressure, a hydroaromatic type inhibitor which contains various hydroaromatics as its main components produced from coal tar fraction was examined by adding it to natural rubber (NR) and styrene-butadiene rubber (SBR). It was found that the inhibitor was as effective as the conventional amine-type inhibitor. From practical viewpoint, heavy hydroaromatics from petroleum (HHAP) was produced by the hydrogenation of the highly aromatic oil from the heavy fraction of petroleum to improve the physical properties of the previous inhibitor from coal tar fraction. From the deterioration tests for NR, SBR, and chloroprene (CR), the following results could be obtained: (1) HHAP showed excellent inhibiting abilities toward NR and CR, exceeding the conventional inhibitor; (2) inhibiting effect toward SBR could be recognized, viscosity and flex cracking were improved by the addition of HHAP. From these results, the hydrogen donation from hydroaromatic is considered to be effective in inhibiting the deterioration of rubbers.

  4. Transcriptome analyses reveal molecular mechanism underlying tapping panel dryness of rubber tree (Hevea brasiliensis)

    PubMed Central

    Li, Dejun; Wang, Xuncheng; Deng, Zhi; Liu, Hui; Yang, Hong; He, Guangming

    2016-01-01

    Tapping panel dryness (TPD) is a serious threat to natural rubber yields from rubber trees, but the molecular mechanisms underlying TPD remain poorly understood. To identify TPD-related genes and reveal these molecular mechanisms, we sequenced and compared the transcriptomes of bark between healthy and TPD trees. In total, 57,760 assembled genes were obtained and analyzed in details. In contrast to healthy rubber trees, 5652 and 2485 genes were up- or downregulated, respectively, in TPD trees. The TPD-related genes were significantly enriched in eight GO terms and five KEGG pathways and were closely associated with ROS metabolism, programmed cell death and rubber biosynthesis. Our results suggest that rubber tree TPD is a complex process involving many genes. The observed lower rubber yield from TPD trees might result from lower isopentenyl diphosphate (IPP) available for rubber biosynthesis and from downregulation of the genes in post-IPP steps of rubber biosynthesis pathway. Our results not only extend our understanding of the complex molecular events involved in TPD but also will be useful for developing effective measures to control TPD of rubber trees. PMID:27005401

  5. Transcriptome analyses reveal molecular mechanism underlying tapping panel dryness of rubber tree (Hevea brasiliensis).

    PubMed

    Li, Dejun; Wang, Xuncheng; Deng, Zhi; Liu, Hui; Yang, Hong; He, Guangming

    2016-01-01

    Tapping panel dryness (TPD) is a serious threat to natural rubber yields from rubber trees, but the molecular mechanisms underlying TPD remain poorly understood. To identify TPD-related genes and reveal these molecular mechanisms, we sequenced and compared the transcriptomes of bark between healthy and TPD trees. In total, 57,760 assembled genes were obtained and analyzed in details. In contrast to healthy rubber trees, 5652 and 2485 genes were up- or downregulated, respectively, in TPD trees. The TPD-related genes were significantly enriched in eight GO terms and five KEGG pathways and were closely associated with ROS metabolism, programmed cell death and rubber biosynthesis. Our results suggest that rubber tree TPD is a complex process involving many genes. The observed lower rubber yield from TPD trees might result from lower isopentenyl diphosphate (IPP) available for rubber biosynthesis and from downregulation of the genes in post-IPP steps of rubber biosynthesis pathway. Our results not only extend our understanding of the complex molecular events involved in TPD but also will be useful for developing effective measures to control TPD of rubber trees. PMID:27005401

  6. Removal of hardness agents, calcium and magnesium, by natural and alkaline modified pumice stones in single and binary systems

    NASA Astrophysics Data System (ADS)

    Sepehr, Mohammad Noori; Zarrabi, Mansur; Kazemian, Hossein; Amrane, Abdeltif; Yaghmaian, Kamiar; Ghaffari, Hamid Reza

    2013-06-01

    Natural and alkaline modified pumice stones were used for the adsorption of water hardening cations, Ca2+ and Mg2+. The adsorbents were characterized using XRF, XRD, SEM and FTIR instrumental techniques. At equilibrium time and for 150 mg/L of a given cation, removal efficiencies were 83% and 94% for calcium and 48% and 73% for magnesium for raw and modified pumices, respectively. The optimal pH for raw and modified pumices were found to be 6.0, leading to the removal of 79 and 96% of calcium and 51 and 93% of magnesium by 10 g/L of raw and modified pumice adsorbents, respectively. Maximum adsorption capacities were 57.27 and 62.34 mg/g for Ca2+ and 44.53 and 56.11 mg/g for Mg2+ on the raw and modified pumices, respectively. Ca2+ and Mg2+ adsorption capacities of the pumice adsorbents decreased in the presence of competing cations. Less than 300 min were needed to achieve 99 and 92% desorption of the adsorbed Ca2+ and 100 and 89% of the adsorbed Mg2+ from the natural and modified pumices, respectively. After treating synthetic water solution simulating an actual water stream with the alkali-modified pumice, total hardness of the treated sample met the required standard for drinking water, namely below 300 mg/L of CaCO3 (297.5 mg/L). The studied pumice adsorbents, and especially the treated pumice, can be therefore considered as promising low cost adsorbents, suitable for the removal of hardness ions from drinking water.

  7. Rubber stopper remover

    DOEpatents

    Stitt, Robert R.

    1994-01-01

    A device for removing a rubber stopper from a test tube is mountable to an upright wall, has a generally horizontal splash guard, and a lower plate spaced parallel to and below the splash guard. A slot in the lower plate has spaced-apart opposing edges that converge towards each other from the plate outer edge to a narrowed portion, the opposing edges shaped to make engagement between the bottom of the stopper flange and the top edge of the test tube to wedge therebetween and to grasp the stopper in the slot narrowed portion to hold the stopper as the test tube is manipulated downwardly and pulled from the stopper. The opposing edges extend inwardly to adjoin an opening having a diameter significantly larger than that of the stopper flange.

  8. Adsorption of Cu(II), Hg(II), and Ni(II) ions by modified natural wool chelating fibers.

    PubMed

    Monier, M; Ayad, D M; Sarhan, A A

    2010-04-15

    The graft copolymerization of ethyl acrylate (EA) onto natural wool fibers initiated by potassium persulphate and Mohr's salt redox initiator system in limited aqueous medium was carried out in heterogeneous media. Ester groups of the grafted copolymers were partially converted into hydrazide function groups followed by hydrazone formation through reaction with isatin. Also the application of the modified fibers for metal ion uptake was studied using Cu(II), Hg(II) and Ni(II). The modified chelating fibers were characterized using FTIR spectroscopy, SEM and X-ray diffraction. PMID:19962235

  9. Sorption of cesium and strontium from mineralized aqueous solutions on natural aluminosilicates modified by ferrocyanides of heavy metals

    SciTech Connect

    Panasyugin, A.S.; Trofimenko, N.E.; Masherova, N.P.; Rat`ko, A.I.; Golikova, N.I.

    1994-03-10

    The sorption behavior of natural aluminosilicates (bentonite and clinoptilolite) and aluminosilicates modified by ferrocyanides of heavy metals has been studied relative to radionuclides {sup 137}Cs and {sup 90}Sr in the presence of various quantities of alkali and alkaline-earth ions (e.g. surface waters). It has been shown that the distribution coefficients of the modified samples may exceed 100 for Sr{sup 2+} and 10,000 for Cs{sup +}; however, with a concentration of mineral background over 1.0 g{center_dot}liter, the competing ions strongly depress the sorption properties of the aluminosilicates.

  10. Identification of a Taraxacum brevicorniculatum rubber elongation factor protein that is localized on rubber particles and promotes rubber biosynthesis.

    PubMed

    Laibach, Natalie; Hillebrand, Andrea; Twyman, Richard M; Prüfer, Dirk; Schulze Gronover, Christian

    2015-05-01

    Two protein families required for rubber biosynthesis in Taraxacum brevicorniculatum have recently been characterized, namely the cis-prenyltransferases (TbCPTs) and the small rubber particle proteins (TbSRPPs). The latter were shown to be the most abundant proteins on rubber particles, where rubber biosynthesis takes place. Here we identified a protein designated T. brevicorniculatum rubber elongation factor (TbREF) by using mass spectrometry to analyze rubber particle proteins. TbREF is homologous to the TbSRPPs but has a molecular mass that is atypical for the family. The promoter was shown to be active in laticifers, and the protein itself was localized on the rubber particle surface. In TbREF-silenced plants generated by RNA interference, the rubber content was significantly reduced, correlating with lower TbCPT protein levels and less TbCPT activity in the latex. However, the molecular mass of the rubber was not affected by TbREF silencing. The colloidal stability of rubber particles isolated from TbREF-silenced plants was also unchanged. This was not surprising because TbREF depletion did not affect the abundance of TbSRPPs, which are required for rubber particle stability. Our findings suggest that TbREF is an important component of the rubber biosynthesis machinery in T. brevicorniculatum, and may play a role in rubber particle biogenesis and influence rubber production. PMID:25809497

  11. Silicone-Rubber Stitching Seal

    NASA Technical Reports Server (NTRS)

    Wang, D. S.

    1985-01-01

    Fabric products protected from raveling by coating threads and filling stitching holes with silicone rubber. Uncored silicone rubber applied to stitching lines with air-pressurized sealant gun. Next, plastic release film placed on coated side, and blanket flipped over so release film lies underneath. Blanket then bagged and adhesive cured under partial vacuum of about 3.5 psi or under pressure. Applications include balloons, parachutes, ultralight aircraft, sails, rescue harnesses, tents, or other fabric products highly stressed in use.

  12. Reinforcement and cut growth in swollen and unswollen filled rubber compounds

    NASA Astrophysics Data System (ADS)

    Chai, Xiaoli

    In reinforced rubber, filler and rubber molecules interact, forming additional "effective crosslinks". During deformation, rubber chains slide (disbond/rebond) over the filler surface. This causes energy dissipation and stress softening, which make it difficult to study filler-rubber interactions. In this thesis, stress-softening was depressed using controlled swelling techniques. Natural rubber compounds filled with different levels of carbon black and silica were made, and cure characteristics determined. Cured samples were swollen to various degrees under controlled conditions. Dynamic mechanical thermal analysis (DMTA), tensile tests and torsion tests were performed using unswollen and swollen samples. Dynamic modulus, Young's modulus, shear modulus and stiffness were compared. At a critical degree of swelling, stiffness and strength dropped greatly, indicating loss of reinforcement. With further swelling, dynamic and tensile moduli were independent of strain, and stress-strain curves started to superimpose. This is hypothesized to result from the disruption of filler-filler and filler-rubber bonds, an important source of filler reinforcement. Cut growth tests were performed on swollen black-filled natural rubber vulcanizates at different strain rates. The effects of swelling and strain rate on cut growth were studied, and crack patterns were observed. Critical cut size was independent of the degree of swelling and strain rate. When equilibrium swelling was reached, crack deviation, due to marked anisotropy of strength in stretched rubber, was suppressed. These observations support the hypothesis that sufficient swelling disrupts the filler network.

  13. Elastin-Based Rubber-Like Hydrogels.

    PubMed

    Desai, Malav S; Wang, Eddie; Joyner, Kyle; Chung, Tae Won; Jin, Hyo-Eon; Lee, Seung-Wuk

    2016-07-11

    We developed rubber-like elastomeric materials using a natural elastin derived sequence and genetic engineering to create precisely defined elastin-like polypeptides. The coiled elastin-like polypeptide chains, which behave like entropic springs, were cross-linked using an end-to-end tethering scheme to synthesize simple hydrogels with excellent extensibility and reversibility. Our hydrogels extend to strains as high as 1500% and remain highly resilient with elastic recovery as high as 94% even at 600% strain, significantly exceeding any other protein-based hydrogel. These materials are valuable as elastomeric hydrogels for designing extremely robust scaffolds useful for tissue engineering. PMID:27257908

  14. Rapid Field Measurement of Rubber Content in Russian Dandelion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber is a critical and strategic raw material for industrial manufacturing and national defense. In 2008, 10 million tons of NR were produced for commercial use, most of it from Hevea brasiliensis in tropical countries. The annual US import deficit for NR is approximately $1 billion. Devel...

  15. High-resolution /sup 27/Al NMR study of the states of aluminum atoms in modified natural mordenite

    SciTech Connect

    Il'in, V.G.; Turutina, N.V.; Brei, V.V.; Voloshinets, V.G.; Onishchenko, A.D.

    1987-09-01

    High-resolution /sup 27/Al NMR has been applied to the states of aluminum in modified natural mordenite. Acid treatment of the natural mordenite and heat treatment of the ammonium form alter the coordination state of 6-8% of the aluminum atoms from tetrahedral (in the framework) to octahedral (at the inner surfaces of the zeolite cavities). In that state, the aluminum can exchange with Na/sup +/, NH/sub 4//sup +/, and other cations. This change in coordination state should have a considerable effect on the catalytic parameters of zeolites.

  16. Modified natural cycle frozen-thawed embryo transfer in patients with repeated implantation failure: An observational study

    PubMed Central

    Arefi, Soheila; Hoseini, Ahmad; Farifteh, Fattaneh; Zeraati, Hojjat

    2016-01-01

    Background: Natural endometrium in Frozen-thawed Embryo Transfer (FET) may have some benefits upon implantation in patients with Repeated Implantation Failure (RIF). It might be due to possible differences between natural and stimulated endometrial growth factors and cytokins secretions. Objective: The objective of this study was to compare the pregnancy rate of FET on modified natural cycle versus hormone replacement therapy (HRT) cycle endometrium in patients with RIF. Materials and Methods: In this observational study the pregnancy rate of patients with RIF undergoing day 3 FET in natural cycle endometrium (group 1, n=56), were compared with another group of patients with RIF in whom frozen-thawed day 3 embryos were transferred on HRT cycle (group 2, n=52). Results: The pregnancy rate in group 1 was 41.07%, compared with the pregnancy rate of group 2; 36.5% (p=0.63). The abortion rate was not significantly different among the groups. Conclusion: It can be concluded that FET in a modified natural cycle is comparable with HRT cycle in patients with RIF. PMID:27525331

  17. Coprocessing of coal and waste rubber

    SciTech Connect

    Farcasiu, M.; Smith, C.M. )

    1992-01-01

    The disposal of used tires, the main source of waste rubber, is an important environmental problem. We describe a method to transform used rubber tires into useful liquid products by coprocessing them with coal. Carbon black, an important constituent in rubber tires, provides a good hydrocracking catalyst during coprocessing. Due to the presence of carbon black in the rubber tires, the yields of liquids obtained by coal-rubber tires coprocessing are superior to those that could be obtained by coprocessing rubber with coal in the absence of carbon black.

  18. Coprocessing of coal and waste rubber

    SciTech Connect

    Farcasiu, M.; Smith, C.M.

    1992-05-01

    The disposal of used tires, the main source of waste rubber, is an important environmental problem. We describe a method to transform used rubber tires into useful liquid products by coprocessing them with coal. Carbon black, an important constituent in rubber tires, provides a good hydrocracking catalyst during coprocessing. Due to the presence of carbon black in the rubber tires, the yields of liquids obtained by coal-rubber tires coprocessing are superior to those that could be obtained by coprocessing rubber with coal in the absence of carbon black.

  19. Recovery of Renibacterium salmoninarum from naturally infected salmonine stocks in Michigan using a modified culture protocol

    USGS Publications Warehouse

    Faisal, M.; Eissa, A.E.; Starliper, C.E.

    2010-01-01

    Renibacterium salmoninarum, the causative agent of bacterial kidney disease (BKD), is a fastidious and slow-growing bacterium that is extremely difficult to grow in vitro. Herein, we describe a modified primary culture protocol that encompasses a modified bacteriological culture medium and a tissue processing procedure. In order to facilitate the release of R. salmoninarum from granulomatous tissues, kidneys of infected fish were homogenized in a high speed stomacher. The kidney disease medium (KDM2), routinely used for primary culture of R. salmoninarum was modified by the addition of antibiotics and metabolites. When a relatively large inoculum of diluted kidney homogenate was streak-plate inoculated onto the modified KDM2, colonial growth of R. salmoninarum was achieved within 5-7. days, compared to the standard of two weeks or more. The modified procedure was then used to determine the prevalence of R. salmoninarum among representative captive and feral salmonid stocks in Michigan. Prevalence and clinical manifestations varied among species, strains of fish, and locations; however, R. salmoninarum isolates were biochemically homogenous. The improved primary culture procedure described in this study enabled selective and quick isolation of R. salmoninarum. Also, the isolates retrieved in this study constitute a unique biological resource for future studies of R. salmoninarum in the Laurentian Great Lakes. ?? 2009 University of Cairo.

  20. Rolling tires into rubber

    SciTech Connect

    Malloy, M.G.

    1997-06-01

    For Envirotire (Lillington, North Carolina), producing quality crumb rubber this summer is all in a night`s work. The tire recycling facility has operated in Lillington, which is about an hour south of Raleigh, North Carolina, for about a year and a half, since October 1995. In the summer, the plant runs at night to save money in electricity costs by operating during off-peak hours; in the winter, daytime hours also can be off-peak. In contrast to the cryogenic systems used elsewhere to recycle tires, Envirotire`s system works on mechanical principles. Before the tires are even shredded, a worker cuts the white-walls out of the tires manually, so the white does not contaminate the black end-product. A worker places the tires manually on a conveyor, which feed them up to an initial shredder that sections them quickly into pieces. While the tires are on the conveyor, dividing strips on the conveyor mark off a place for each tire. The system takes nine new tires per minute.

  1. Radiation graft modification of EPDM rubber

    NASA Astrophysics Data System (ADS)

    Katbab, A. A.; Burford, R. P.; Garnett, J. L.

    N-Vinyl pyrrolidone (NVP), 2-hydroxyethylmethacrylate (HEMA) and acrylamide (AAm) have been grafted to the surface of rubber vulcanizates based on ethylene-propylene-terpolymer (EPDM) using the simultaneous radiation method to alter surface properties such as wettability and therefore biocompatibility. The effect of monomer concentration, solvent and EPDM structural factors on the grafting behavior have been investigated. The inhibitory effect upon homopolymerization of various salts has also been evaluated for the three monomers. NVP and HEMA could be grafted onto EPDM rubber in the presence of aqueous solutions of cupric nitrate at 0.005 M and 1.0 M concentrations respectively. Aqueous solutions of Mohr's salt (ammonium ferrous sulphate) at 0.05 M not only suppressed the homopolymerization of AAm but also increased grafting yield. The percentage grafting also increased with increasing AAm concentration. A mechanism has been proposed to explain the behaviour of these monomers. The inclusion of multifunctional acrylates in additive amounts (1.0 vol%) enhanced the graft degree. Modified samples were able to be efficiently stained, allowing the depth of the graft copolymerization to be determined by light microscopy. Water was found to have an accelerating effect on the polymerization of these monomers, but methanol prevented their polymerization completely. The effect of EPDM structural factors upon degree of grafting was found to vary, depending upon the monomer type.

  2. Strategies to improve the adhesion of rubbers to adhesives by means of plasma surface modification

    NASA Astrophysics Data System (ADS)

    Martín-Martínez, J. M.; Romero-Sánchez, M. D.

    2006-05-01

    The surface modifications produced by treatment of a synthetic sulfur vulcanized styrene-butadiene rubber with oxidizing (oxygen, air, carbon dioxide) and non oxidizing (nitrogen, argon) RF low pressure plasmas, and by treatment with atmospheric plasma torch have been assessed by ATR-IR and XPS spectroscopy, SEM, and contact angle measurements. The effectiveness of the low pressure plasma treatment depended on the gas atmosphere used to generate the plasma. A lack of relationship between surface polarity and wettability, and peel strength values was obtained, likely due to the cohesive failure in the rubber obtained in the adhesive joints. In general, acceptable adhesion values of plasma treated rubber were obtained for all plasmas, except for nitrogen plasma treatment during 15 minutes due to the creation of low molecular weight moieties on the outermost rubber layer. A toluene wiping of the N{2 } plasma treated rubber surface for 15 min removed those moieties and increased adhesion was obtained. On the other hand, the treatment of the rubber with atmospheric pressure by means of a plasma torch was proposed. The wettability of the rubber was improved by decreasing the rubber-plasma torch distance and by increasing the duration because a partial removal of paraffin wax from the rubber surface was produced. The rubber surface was oxidized by the plasma torch treatment, and the longer the duration of the plasma torch treatment, the higher the degree of surface oxidation (mainly creation of C O moieties). However, although the rubber surface was effectively modified by the plasma torch treatment, the adhesion was not greatly improved, due to the migration of paraffin wax to the treated rubber-polyurethane adhesive interface once the adhesive joint was produced. On the other hand, the extended treatment with plasma torch facilitated the migration of zinc stearate to the rubber-adhesive interface, also contributing to deteriorate the adhesion in greater extent. Finally

  3. Characteristics of rubber used in seismic isolation by digital and thermal image analysis

    NASA Astrophysics Data System (ADS)

    Lewangamage, Chamindalal S.; Abe, Masato; Fujino, Yozo; Yoshida, Junji

    2002-06-01

    The use of seismic isolation rubber bearings in bridges and buildings provides a very effective passive method to suppress hazard from earthquake-induced vibration. Carbons filled natural rubber and high damping rubber (HDR) are smart civil engineering materials especially used in those bearings. This study is to develop algorithms for large strain field measurements in rubber material by image analysis and to experimentally investigate temperature dependency on rubber behavior under cyclic loadings by thermal image analysis. A correlation-based template-matching algorithm is developed in displacement field measurements in continua so that a large strain field can be measured. Possible unrealistic displacement vectors present in measured displacement fields are eliminated by new algorithm in which the deformation should satisfy the continuity condition. The algorithms are successfully employed in strain field measurement of rubber materials reported here as experimental verification. Local deformational characteristics of rubber were also studied; results are shown by the analysis. Finally, a failure criterion was proposed for the rubber. The use of infrared thermographs to measure temperature field is described. This paper will discuss its application in HDR temperature field measurements under cyclic loadings. In HDR, various changes of properties were investigated with respect to the frequencies of loadings and its body temperature; results are shown by the analysis.

  4. Transcriptome and gene expression analysis in cold-acclimated guayule (Parthenium argentatum) rubber-producing tissue.

    PubMed

    Ponciano, Grisel; McMahan, Colleen M; Xie, Wenshuang; Lazo, Gerard R; Coffelt, Terry A; Collins-Silva, Jillian; Nural-Taban, Aise; Gollery, Martin; Shintani, David K; Whalen, Maureen C

    2012-07-01

    Natural rubber biosynthesis in guayule (Parthenium argentatum Gray) is associated with moderately cold night temperatures. To begin to dissect the molecular events triggered by cold temperatures that govern rubber synthesis induction in guayule, the transcriptome of bark tissue, where rubber is produced, was investigated. A total of 11,748 quality expressed sequence tags (ESTs) were obtained. The vast majority of ESTs encoded proteins that are similar to stress-related proteins, whereas those encoding rubber biosynthesis-related proteins comprised just over one percent of the ESTs. Sequence information derived from the ESTs was used to design primers for quantitative analysis of the expression of genes that encode selected enzymes and proteins with potential impact on rubber biosynthesis in field-grown guayule plants, including 3-hydroxy-3-methylglutaryl-CoA synthase, 3-hydroxy-3-methylglutaryl-CoA reductase, farnesyl pyrophosphate synthase, squalene synthase, small rubber particle protein, allene oxide synthase, and cis-prenyl transferase. Gene expression was studied for field-grown plants during the normal course of seasonal variation in temperature (monthly average maximum 41.7 °C to minimum 0 °C, from November 2005 through March 2007) and rubber transferase enzymatic activity was also evaluated. Levels of gene expression did not correlate with air temperatures nor with rubber transferase activity. Interestingly, a sudden increase in night temperature 10 days before harvest took place in advance of the highest CPT gene expression level. PMID:22608127

  5. Enhancement of carbon-steel peel adhesion to rubber blend using atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Kršková, Jana; Skácelová, Dana; Kováčik, Dušan; Ráhel', Jozef; Pret'o, Jozef; Černák, Mirko

    2016-08-01

    The surface of carbon-steel plates was modified by non-equilibrium plasma of diffuse coplanar surface barrier discharge (DCSBD) in order to improve the adhesive properties to the NR (natural rubber) green rubber compound. The effect of different treatment times as well as different input power and frequency of supplied high voltage was investigated. The samples were characterized using contact angle and surface free energy measurement, measurement of adhesive properties, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Surface chemical composition was studied by energy-dispersive X-ray spectroscopy (EDX). Significant increase in wettability was observed even after 2 s of plasma exposure. The surface modification was confirmed also by peel test, where the best results were obtained for 6 s of plasma treatment. In addition the ageing effect was studied to investigate the durability of modification, which is crucial for the industrial applications. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  6. Development of modified release gliclazide biological macromolecules using natural biodegradable polymers.

    PubMed

    Prajapati, Vipulkumar D; Mashru, Krupa H; Solanki, Himanshu K; Jani, Girish K

    2013-04-01

    Modified release biological macromolecules (beads) of gliclazide using sodium alginate combined with either gellan gum or pectin in different ratios were prepared by Ionotropic gelation method. Biological macromolecules were evaluated for different physico-chemical parameters. Increase in polymers proportion showed difficulty in production of biological macromolecules due to high viscosity of dispersion. As the polymer concentration increases, the swelling and entrapment efficiency of drug increased. Compared to all other batches and commercial modified release gliclazide tablet, formulated biological macromolecules of sodium alginate with pectin (2:1 ratio) and with gellan gum (6:0.75 ratio) exhibited spherical shape, biphasic in vitro release profile and initial high drug release followed by moderate release up to 12 h as matrix diffusion kinetics and Higuchi model as well as Korsmeyer model. PMID:23305705

  7. Improved photostability of hydrophobic natural dye incorporated in organo-modified hydrotalcite

    NASA Astrophysics Data System (ADS)

    Kohno, Yoshiumi; Asai, Saeko; Shibata, Masashi; Fukuhara, Choji; Maeda, Yasuhisa; Tomita, Yasumasa; Kobayashi, Kenkichiro

    2014-08-01

    β-carotene and annatto extract are typical carotenoids used as safe colorants for foods. However, the instability against irradiation limits their wide use. The improvement of stability was investigated by the intercalation of dye into the interlayer space of the anion-exchangeable clay, hydrotalcite. A hydrophobic environment was constructed in the interlayer space of the hydrotalcite by its modification with anionic surfactants (dodecyl sulfate and dodecylbenzene sulfonate). The lipophilic β-carotene and annatto dye were successfully incorporated into the organo-modified hydrotalcite, and the incorporated dyes exhibited improved photostability under visible irradiation from a 100 W halogen lamp (190 klux) in the air. The effect of the stabilization on the anionic annatto dye was higher by the incorporation in the modified hydrotalcite than that in the modified cation exchangeable clay, suggesting that the polarity of the clay sheet had some influence on the stabilization of the incorporated dye. The stabilization effect of β-carotene was not so significant as that of the annatto dye, because sufficient intercalation of non-polar β-carotene might require stronger hydrophobic environment. The π-π interaction between the β-carotene and the benzene ring of dodecylbenzene sulfonate was found to contribute to the stability enhancement.

  8. Rubber friction and tire dynamics.

    PubMed

    Persson, B N J

    2011-01-12

    We propose a simple rubber friction law, which can be used, for example, in models of tire (and vehicle) dynamics. The friction law is tested by comparing numerical results to the full rubber friction theory (Persson 2006 J. Phys.: Condens. Matter 18 7789). Good agreement is found between the two theories. We describe a two-dimensional (2D) tire model which combines the rubber friction model with a simple mass-spring description of the tire body. The tire model is very flexible and can be used to accurately calculate μ-slip curves (and the self-aligning torque) for braking and cornering or combined motion (e.g. braking during cornering). We present numerical results which illustrate the theory. Simulations of anti-blocking system (ABS) braking are performed using two simple control algorithms. PMID:21406818

  9. Rubber friction and tire dynamics

    NASA Astrophysics Data System (ADS)

    Persson, B. N. J.

    2011-01-01

    We propose a simple rubber friction law, which can be used, for example, in models of tire (and vehicle) dynamics. The friction law is tested by comparing numerical results to the full rubber friction theory (Persson 2006 J. Phys.: Condens. Matter 18 7789). Good agreement is found between the two theories. We describe a two-dimensional (2D) tire model which combines the rubber friction model with a simple mass-spring description of the tire body. The tire model is very flexible and can be used to accurately calculate μ-slip curves (and the self-aligning torque) for braking and cornering or combined motion (e.g. braking during cornering). We present numerical results which illustrate the theory. Simulations of anti-blocking system (ABS) braking are performed using two simple control algorithms.

  10. Pressure sensitive conductive rubber blends

    SciTech Connect

    Hassan, H.H. ); Abdel-Bary, E.M. ); El-Mansy, M.K.; Khodair, H.A. )

    1989-12-01

    Butadiene-acrylonitrile rubber (NBR) was blended with polychloroprene (CR) according to standard techniques. The blend was mixed with different concentrations of ZnO. The vulcanized sample was subjected to electrical conductivity ({sigma}) measurements while different values of static pressure were applied on the sample. It was found that samples containing 7.5 phr ZnO showed a reasonable pressure sensitive increase of {sigma}. Furthermore, the {sigma} vs pressure relationship of rubber blend mixed with different concentrations of Fast Extrusion Furnace black (FEF) was investigated. It was found that rubber vulcanizate containing 40 phr FEF resulted in a negative value of the pressure coefficient of conductivity {approx equal} {minus} 4.5 KPa{sup {minus}1}.

  11. Reinforced rubber composition containing ground coal

    SciTech Connect

    Sperley, R.J.

    1984-10-16

    A reinforced rubber composition is provided comprising a mixture of (a) a sulfur vulcanizable rubber and (b) ground coal having an average mesh size of 25 or more and which produces an aqueous slurry with a pH of less than 7.0, and wherein a metallic reinforcing member is embedded in the rubber mixture of (a) and (b).

  12. Friction characteristics of three 30 by 11.5-14.5, type 8, aircraft tires with various tread groove patterns and rubber compounds

    NASA Technical Reports Server (NTRS)

    Yager, T. J.; Mccarty, J. L.

    1977-01-01

    A test program was conducted to evaluate friction performance and wear characteristics on wet runways of three 30 x 11.5-14.5, type, aircraft tires having two different tread patterns and natural rubber contents. All test tires had the standard three circumferential groove tread, but two had molded transverse grooves which extended from shoulder to shoulder. The tread rubber content of the two tires with transverse grooves differed in that one had a 100 percent natural rubber tread and the other had a rubber tread composition that was 30 percent synthetic and 70 percent natural. The third test tire had the conventional 100 percent natural rubber tread. Results indicate that the differences in tire tread design and rubber composition do not significantly affect braking and cornering friction capability on wet or dry surfaces. Braking performance of the tires decreases with increased speed, with increased yaw angle and, at higher speeds, with increased wetness of the surface.

  13. Removal of natural organic matter (NOM) from an aqueous solution by NaCl and surfactant-modified clinoptilolite.

    PubMed

    Niri, Mehdi Vosoughi; Mahvi, Amir Hosein; Alimohammadi, Mahmoud; Shirmardi, Mohammad; Golastanifar, Hafez; Mohammadi, Mohamma Javad; Naeimabadi, Abolfazl; Khishdost, Maria

    2015-06-01

    Zeolitic tuffs are found in different parts of the world. Iranian zeolite is a low-cost material that can be frequently found in nature. Surfactant-modified zeolite (SMZ) can be used for the adsorption of natural organic matter (NOM) from aqueous solutions. The adsorption study was conducted to evaluate the adsorption capacity of SMZ; furthermore, the effects of contact time, initial pH, and the initial adsorbent dose on the adsorption process were investigated in a batch system. The kinetic studies showed that the adsorption of NOM on SMZ was a gradual process. The optimum initial pH values for the adsorption of NOM on SMZ were in the acidic ranges. The batch kinetic experiments showed that the adsorption followed the pseudo-second-order kinetic model with good correlation coefficients. The equilibrium data were well described by the Langmuir isotherm model. The results show that the natural zeolite being modified with NaCl and hexadecyltrimethylammonium bromide as a cationic surfactant was an appropriate adsorbent for the removal of NOM. PMID:26042972

  14. Stress-Strain Relation and strain-Induced Crystallization in Rubber

    SciTech Connect

    Toki,S.

    2006-01-01

    Rubber is composed of flexible chains and network points. Theory of rubber elasticity succeeds to elucidate stress-strain relation of rubber using the inverse Langevin equation of entropy modulus. However, actual rubber is much different from ideal networks composed of ideal rubber chains. Network points may not distribute homogeneously and the molecular weight between two network points may show wide distribution. Flexible chains show strain-induced crystallization. Recent synchrotron X-ray and simultaneous stress-strain measurements reveal that strain-induced crystallization reduces the stress by increasing the length of molecules along the stretching direction. Also, strain-induced crystals are created not at the middle of the network points, but at the close location to the network points. The hybrid structure of strain-induced crystallites and network points may be stronger than network points alone. Therefore, strain induced crystallization may increase the tensile strength of rubber by two mechanisms, they are, increase of elongation at break and reinforcement of network points. Natural rubber has biotic network points in nature. After vulcanization, the biotic network may contribute the superior toughness of NR, comparing to IR. Carbon filled NR also shows strain induced crystallization. In order to acquire high tensile strength, molecules should have higher flexibility to perform strain induced crystallization by selecting a kind of carbon blacks, an accelerator and a curing condition.

  15. Modified procedure for extraction of poliovirus from naturally-infected oysters using Cat-Floc and beef extract

    SciTech Connect

    Landry, E.F.; Vaughn, J.M.; Vicale, T.J.

    1980-02-01

    Methods for recovery of poliovirus type 1 from naturally-infected oysters were examined. Extraction procedures analyzed included glycine-saline and polyelectrolyte (Cat-Floc) methods followed by concentration using modifications of an acid precipitation technique. Direct viral assay of shellfish homogenates, when compared to virus recovery following extraction, indicated that substantially fewer viruses were detected in initial homogenates. These data appeared to support the contention that input values based on homogenate assay were inappropriate in determining recovery efficiencies with naturally-infected shellfish. Since absolute efficiencies could not be determined, relative efficiencies using samples from pooled homogenates were used to determine the recovery efficiencies of various extraction procedures. Cat-Floc extraction followed by a beef extract-modified acid precipitation technique resulted in higher virus recoveries than a glycine-saline extraction procedure.

  16. Tasks, Teacher Feedback, and Learner Modified Output in Naturally Occurring Classroom Interaction

    ERIC Educational Resources Information Center

    Gurzynski-Weiss, Laura; Revesz, Andrea

    2012-01-01

    Tasks and interactional feedback have received much attention in instructed second language acquisition research in recent years. However, little research exists that has investigated feedback and task factors together during naturally occurring teacher-student interaction in classroom settings. To bridge this gap, the current study explored the…

  17. A Fuzzy Set Approach to Modifiers and Vagueness in Natural Language

    ERIC Educational Resources Information Center

    Hersh, Harry M.; Caramazza, Alfonso

    1976-01-01

    The proposition that natural language concepts are represented as fuzzy sets, a generalization of the traditional theory of sets, of meaning components and that language operators--adverbs, negative markers, and adjectives--can be considered as operators on fuzzy sets was assessed empirically. (Editor/RK)

  18. HbNIN2, a cytosolic alkaline/neutral-invertase, is responsible for sucrose catabolism in rubber-producing laticifers of Hevea brasiliensis (para rubber tree).

    PubMed

    Liu, Shujin; Lan, Jixian; Zhou, Binhui; Qin, Yunxia; Zhou, Yihua; Xiao, Xiaohu; Yang, Jianghua; Gou, Jiqing; Qi, Jiyan; Huang, Yacheng; Tang, Chaorong

    2015-04-01

    In Hevea brasiliensis, an alkaline/neutral invertase (A/N-Inv) is responsible for sucrose catabolism in latex (essentially the cytoplasm of rubber-producing laticifers, the source of natural rubber) and implicated in rubber yield. However, neither the gene encoding this enzyme nor its molecular and biochemical properties have been well documented. Three Hevea A/N-Inv genes, namely HbNIN1, 2 and 3, were first cloned and characterized in planta and in Escherichia coli. Cellular localizations of HbNIN2 mRNA and protein were probed. From latex, active A/N-Inv proteins were purified, identified, and explored for enzymatic properties. HbNIN2 was identified as the major A/N-Inv gene functioning in latex based on its functionality in E. coli, its latex-predominant expression, the conspicuous localization of its mRNA and protein in the laticifers, and its expressional correlation with rubber yield. An active A/N-Inv protein was partially purified from latex, and determined as HbNIN2. The enhancement of HbNIN2 enzymatic activity by pyridoxal is peculiar to A/N-Invs in other plants. We conclude that HbNIN2, a cytosolic A/N-Inv, is responsible for sucrose catabolism in rubber laticifers. The results contribute to the studies of sucrose catabolism in plants as a whole and natural rubber synthesis in particular. PMID:25581169

  19. Plasma-enhanced deposition of antifouling layers on silicone rubber surfaces

    NASA Astrophysics Data System (ADS)

    Jiang, Hongquan

    In food processing and medical environments, biofilms serve as potential sources of contamination, and lead to food spoilage, transmission of diseases or infections. Because of its ubiquitous and recalcitrant nature, Listeria monocytogenes biofilm is especially hard to control. Generating antimicrobial surfaces provide a method to control the bacterial attachment. The difficulty of silver deposition on polymeric surfaces has been overcome by using a unique two-step plasma-mediated method. First silicone rubber surfaces were plasma-functionalized to generate aldehyde groups. Then thin silver layers were deposited onto the functionalized surfaces according to Tollen's reaction. X-ray photoelectron spectroscopy (XPS), atomic force spectroscopy (AFM) and scanning electron microscopy (SEM) showed that silver particles were deposited. By exposing the silver coated surfaces to L. monocytogenes, it was demonstrated that they were bactericidal to L. monocytogenes. No viable bacteria were detected after 12 to 18 h on silver-coated silicone rubber surfaces. Another antifouling approach is to generate polyethylene glycol (PEG) thin layer instead of silver on polymer surfaces. Covalent bond of PEG structures of various molecular weights to cold-plasma-functionalized polymer surfaces, such as silicone rubber, opens up a novel way for the generation of PEG brush-like or PEG branch-like anti-fouling layers. In this study, plasma-generated surface free radicals can react efficiently with dichlorosilane right after plasma treatment. With the generation of halo-silane groups, this enables PEG molecules to be grafted onto the modified surfaces. XPS data clearly demonstrated the presence of PEG molecules on plasma-functionalized silicone rubber surfaces. AFM images showed the changed surface morphologies as a result of covalent attachment to the surface of PEG molecules. Biofilm experiment results suggest that the PEG brush-like films have the potential ability to be the next

  20. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    Bauman, Bernard D.; Williams, Mark A.; Bagheri, Reza

    1997-12-02

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles.

  1. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    McInnis, E.L.; Bauman, B.D.; Williams, M.A.

    1996-04-09

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles. 2 figs.

  2. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    McInnis, E.L.; Scharff, R.P.; Bauman, B.D.; Williams, M.A.

    1995-01-17

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles. 2 figures.

  3. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    McInnis, Edwin L.; Scharff, Robert P.; Bauman, Bernard D.; Williams, Mark A.

    1995-01-01

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles.

  4. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    McInnis, Edwin L.; Bauman, Bernard D.; Williams, Mark A.

    1996-04-09

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles.

  5. Higher modulus compositions incorporating particulate rubber

    DOEpatents

    Bauman, B.D.; Williams, M.A.; Bagheri, R.

    1997-12-02

    Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles. 2 figs.

  6. Sprayed Coating Renews Butyl Rubber

    NASA Technical Reports Server (NTRS)

    Martin, R. B.

    1982-01-01

    Damaged butyl rubber products are renewed by spray technique originally developed for protective suits worn by NASA workers. A commercial two-part adhesive is mixed with Freon-113 (or equivalent) trichlorotrifluoroethane to obtain optimum viscosity for spraying. Mix is applied with an external-air-mix spray gun.

  7. CHEMICAL RECLAMATION OF SCRAP RUBBER

    EPA Science Inventory

    A conceptual, commercial-scale plant design was formulated for processing 22,500 t/yr of scrap rubber tires to hydrocarbon fuel gases, oils, petrochemicals (principally ethylene and aromatic liquids), and carbon black. The process is based upon molten salt (zinc chloride) pyrolys...

  8. Development of controlled release spheroids using natural polysaccharide as release modifier.

    PubMed

    Kulkarni, Giriraj T; Gowthamarajan, K; Dhobe, Rohan R; Yohanan, Fenni; Suresh, B

    2005-01-01

    A polysaccharide hydrogel was isolated from the seeds of Tamarindus indica (tamarind) and was used as release modifier for the preparation of diclofenac sodium spheroids, using extrusion-spheronization technique. The process was studied for the effect of variables to arrive at spheroids with satisfactory particle shape, size and size-distribution. The prepared spheroids were characterized for surface morphology, qualitative surface porosity, friability, bulk density, and flow properties. The in vitro release studies exhibited a zero-order release kinetics that was confirmed by Higuchi's and Peppas' models. A credible correlation was obtained among swelling index, viscosity, surface roughness of the polysaccharide, and in vitro dissolution profile of the spheroids. In the comparative bioavailability study, we found that the developed spheroids were able to sustain the drug release over 8 hr and could improve the extent of absorption and bioavailability of the drug. PMID:16036714

  9. On the nature of cross-isobath energy fluxes in topographically modified barotropic semidiurnal Kelvin waves

    NASA Astrophysics Data System (ADS)

    Zhang, Tianyi; Yankovsky, Alexander E.

    2016-05-01

    Continental shelf topography modifies a Kelvin wave into a hybrid Kelvin-edge wave with a nonzero across-isobath velocity and a phase speed that decreases with increasing wave number while the group velocity reaches a minimum at intermediate wave numbers. We model the modified semidiurnal Kelvin wave adjustment to alongshore changes in the shelf width. The model domain consists of two alongshore-uniform continental shelves of different widths adjoined through a 150 km long transition zone. The continental shelf and slope are adjacent to an ocean of a constant depth, allowing radiation of Poincaré waves. We consider three shelf widths of 150, 250, and 300 km, where properties of a zero mode at semidiurnal frequency change from Kelvin wave like to edge wave like. For each shelf width, a zero wave mode has its distinctive alongshore energy flux structure on the shelf. As the incident wave encounters a variable shelf width, the alongshore energy flux converges (diverges) on the shelf resulting in an offshore (onshore) energy flux over the continental slope. Furthermore, for a strongly convergent alongshore energy flux, the incident wave mode scatters into radiating Poincaré waves. On sufficiently wide shelves, a strong across-isobath energy flux comparable with the incident wave energy flux can be triggered even by relatively modest changes of shelf width. An energy flux divergence parameter De is defined, which scales with magnitude and direction of the energy flux across the continental slope. More than 50% of the incident energy flux scatters into modes radiating offshore when De is -1 or less.

  10. Fish assemblages at engineered and natural channel structures in the lower Missouri river: implications for modified dike structures

    USGS Publications Warehouse

    Schloesser, J.T.; Paukert, Craig P.; Doyle, W.J.; Hill, T.; Steffensen, K.D.; Travnichek, Vincent H.

    2012-01-01

    Large rivers throughout the world have been modified by using dike structures to divert water flows to deepwater habitats to maintain navigation channels. These modifications have been implicated in the decline in habitat diversity and native fishes. However, dike structures have been modified in the Missouri River USA to increase habitat diversity to aid in the recovery of native fishes. We compared species occupancy and fish community composition at natural sandbars and at notched and un-notched rock dikes along the lower Missouri River to determine if notching dikes increases species diversity or occupancy of native fishes. Fish were collected using gill nets, trammel nets, otter trawls, and mini fyke nets throughout the lower 1212 river km of the Missouri River USA from 2003 to 2006. Few differences in species richness and diversity were evident among engineered dike structures and natural sandbars. Notching a dike structure had no effect on proportional abundance of fluvial dependents, fluvial specialists, and macrohabitat generalists. Occupancy at notched dikes increased for two species but did not differ for 17 other species (81%). Our results suggest that dike structures may provide suitable habitats for fluvial species compared with channel sand bars, but dike notching did not increase abundance or occupancy of most Missouri River fishes. Published in 2011 by John Wiley & Sons, Ltd.

  11. Modifying the luteal phase support in natural cycle frozen-thawed embryo transfer improves cycle outcome.

    PubMed

    Haas, Jigal; Lantsberg, Daniel; Feldman, Noa; Manela, Daphna; Machtinger, Ronit; Dar, Shir; Rabinovici, Jaron; Orvieto, Raoul

    2015-01-01

    With the recent trend toward single embryo transfer (ET), cryopreservation of extraneous embryos is becoming increasingly prevalent. Several replacement protocols for frozen-thawed ET (FET) exist, with no advantage of one protocol over the others. All consecutive patients undergoing natural cycle Day-3 FET cycles between May 2012 and March 2015 in our IVF unit were evaluated. While following spontaneous ovulation, all patients received progesterone luteal support. Since June 2014, patients underwent the same aforementioned natural cycle FET cycles, with two additional injections, one of recombinant hCG (250 mcg) and the other of GnRH-agonist (triptorelin 0.1 mg), on the day of transfer and 4 d later, respectively. While the patients' clinical characteristics, the prevalence of embryos that survived the thawing process and the number of embryos transferred were comparable between the earlier as compared with the later period, implantation rate, positive β-hCG, clinical, and ongoing pregnancy rates were significantly higher during the later period. We, therefore, suggest that when natural cycle FET is offered, the addition of two injections of recombinant hCG and GnRH-agonist, on the day of transfer and 4 d later, respectively, might increase clinical pregancy rates. Further large prospective studies are needed to elucidate the aforementioned recommendation prior to its routine implementation. PMID:26288149

  12. Recognition of Porphyromonas gingivalis Gingipain Epitopes by Natural IgM Binding to Malondialdehyde Modified Low-Density Lipoprotein

    PubMed Central

    Turunen, S. Pauliina; Kummu, Outi; Harila, Kirsi; Veneskoski, Marja; Soliymani, Rabah; Baumann, Marc; Pussinen, Pirkko J.; Hörkkö, Sohvi

    2012-01-01

    Objective Increased risk for atherosclerosis is associated with infectious diseases including periodontitis. Natural IgM antibodies recognize pathogen-associated molecular patterns on bacteria, and oxidized lipid and protein epitopes on low-density lipoprotein (LDL) and apoptotic cells. We aimed to identify epitopes on periodontal pathogen Porphyromonas gingivalis recognized by natural IgM binding to malondialdehyde (MDA) modified LDL. Methods and Results Mouse monoclonal IgM (MDmAb) specific for MDA-LDL recognized epitopes on P. gingivalis on flow cytometry and chemiluminescence immunoassays. Immunization of C57BL/6 mice with P. gingivalis induced IgM, but not IgG, immune response to MDA-LDL and apoptotic cells. Immunization of LDLR−/− mice with P. gingivalis induced IgM, but not IgG, immune response to MDA-LDL and diminished aortic lipid deposition. On Western blot MDmAb bound to P. gingivalis fragments identified as arginine-specific gingipain (Rgp) by mass spectrometry. Recombinant domains of Rgp produced in E. coli were devoid of phosphocholine epitopes but contained epitopes recognized by MDmAb and human serum IgM. Serum IgM levels to P. gingivalis were associated with anti-MDA-LDL levels in humans. Conclusion Gingipain of P. gingivalis is recognized by natural IgM and shares molecular identity with epitopes on MDA-LDL. These findings suggest a role for natural antibodies in the pathogenesis of two related inflammatory diseases, atherosclerosis and periodontitis. PMID:22496875

  13. A new paradigm for the molecular basis of rubber elasticity

    SciTech Connect

    Hanson, David E.; Barber, John L.

    2015-02-19

    The molecular basis for rubber elasticity is arguably the oldest and one of the most important questions in the field of polymer physics. The theoretical investigation of rubber elasticity began in earnest almost a century ago with the development of analytic thermodynamic models, based on simple, highly-symmetric configurations of so-called Gaussian chains, i.e. polymer chains that obey Markov statistics. Numerous theories have been proposed over the past 90 years based on the ansatz that the elastic force for individual network chains arises from the entropy change associated with the distribution of end-to-end distances of a free polymer chain. There are serious philosophical objections to this assumption and others, such as the assumption that all network nodes undergo affine motion and that all of the network chains have the same length. Recently, a new paradigm for elasticity in rubber networks has been proposed that is based on mechanisms that originate at the molecular level. Using conventional statistical mechanics analyses, quantum chemistry, and molecular dynamics simulations, the fundamental entropic and enthalpic chain extension forces for polyisoprene (natural rubber) have been determined, along with estimates for the basic force constants. Concurrently, the complex morphology of natural rubber networks (the joint probability density distributions that relate the chain end-to-end distance to its contour length) has also been captured in a numerical model. When molecular chain forces are merged with the network structure in this model, it is possible to study the mechanical response to tensile and compressive strains of a representative volume element of a polymer network. As strain is imposed on a network, pathways of connected taut chains, that completely span the network along strain axis, emerge. Although these chains represent only a few percent of the total, they account for nearly all of the elastic stress at high strain. Here we provide a brief

  14. Electrospinning of Nanodiamond-Modified Polysaccharide Nanofibers with Physico-Mechanical Properties Close to Natural Skins.

    PubMed

    Mahdavi, Mina; Mahmoudi, Nafiseh; Rezaie Anaran, Farzad; Simchi, Abdolreza

    2016-01-01

    Electrospinning of biopolymers has gained significant interest for the fabrication of fibrous mats for potential applications in tissue engineering, particularly for wound dressing and skin regeneration. In this study, for the first time, we report successful electrospinning of chitosan-based biopolymers containing bacterial cellulous (33 wt %) and medical grade nanodiamonds (MND) (3 nm; up to 3 wt %). Morphological studies by scanning electron microscopy showed that long and uniform fibers with controllable diameters from 80 to 170 nm were prepared. Introducing diamond nanoparticles facilitated the electrospinning process with a decrease in the size of fibers. Fourier transform infrared spectroscopy determined hydrogen bonding between the polymeric matrix and functional groups of MND. It was also found that beyond 1 wt % MND, percolation networks of nanoparticles were formed which affected the properties of the nanofibrous mats. Uniaxial tensile testing of the woven mats determined significant enhancement of the strength (from 13 MPa to 25 MP) by dispersion of 1 wt % MND. The hydrophilicity of the mats was also remarkably improved, which was favorable for cell attachment. The water vapor permeability was tailorable in the range of 342 to 423 µg·Pa(-1)·s(-1)·m(-1). The nanodiamond-modified mats are potentially suitable for wound healing applications. PMID:27399726

  15. Electrospinning of Nanodiamond-Modified Polysaccharide Nanofibers with Physico-Mechanical Properties Close to Natural Skins

    PubMed Central

    Mahdavi, Mina; Mahmoudi, Nafiseh; Rezaie Anaran, Farzad; Simchi, Abdolreza

    2016-01-01

    Electrospinning of biopolymers has gained significant interest for the fabrication of fibrous mats for potential applications in tissue engineering, particularly for wound dressing and skin regeneration. In this study, for the first time, we report successful electrospinning of chitosan-based biopolymers containing bacterial cellulous (33 wt %) and medical grade nanodiamonds (MND) (3 nm; up to 3 wt %). Morphological studies by scanning electron microscopy showed that long and uniform fibers with controllable diameters from 80 to 170 nm were prepared. Introducing diamond nanoparticles facilitated the electrospinning process with a decrease in the size of fibers. Fourier transform infrared spectroscopy determined hydrogen bonding between the polymeric matrix and functional groups of MND. It was also found that beyond 1 wt % MND, percolation networks of nanoparticles were formed which affected the properties of the nanofibrous mats. Uniaxial tensile testing of the woven mats determined significant enhancement of the strength (from 13 MPa to 25 MP) by dispersion of 1 wt % MND. The hydrophilicity of the mats was also remarkably improved, which was favorable for cell attachment. The water vapor permeability was tailorable in the range of 342 to 423 µg·Pa−1·s−1·m−1. The nanodiamond-modified mats are potentially suitable for wound healing applications. PMID:27399726

  16. Modified natural fibrils for structural hybrid composites: Towards an investigation of textile reduction

    NASA Astrophysics Data System (ADS)

    Ufodike, Chukwuzubelu Okenwa

    Recently, the interest for renewable resources for fibers particularly of plant origin has been increasing. Reduction of use of traditional textile materials is now considered more critical due to the increasing environmental concern. Natural fibers are renewable, biodegradable, recyclable, and lightweight materials with high specific modulus, in competition with man-made fossil materials and fiberglass. Natural fibers are used for preparation of functionalized textiles to achieve smart and intelligent properties. However, the incorporation of these fibers in composite systems has been challenging due to their hydrophilic nature. Nevertheless, the fact that these biodegradable materials can be manipulated at a nano-scale to complement desired objective and application has made them a favorable option. The idea behind this project is to explore ways to convert green waste to high value materials and to utilize natural building blocks to design textile reinforcement materials. In this work, cellulose nanofibrils (CNF) supplied from the University of Maine were hydrophobized by silylation and characterized using Fourier-Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, and Thermogravimetric analysis (TGA). Results from FTIR spectroscopy showed a formation of Si-O-C bonds, indicating better fiber-matrix adhesion. Raman spectroscopy showed disruption of hydrogen bonding which indicates interference of parallel nanocellulose fiber adhesion to neighboring fibrils. The TGA suggests that the thermal stability of the functionalized CNF is higher than that of the corresponding neat sample, which could be a result of stable Si bond formation. The raw materials (neat and functionalized) were encapsulated in a polystyrene matrix through a solvent and non-solvent precipitation process, and then extruded using single and dual heat processing. The extruded thin filaments were tested according to the ASTM D638 (tensile test of plastics). Results showed an increasing

  17. Plasma polymerized primer for rubber-to-metal bonding: Adhesion measurement and interphase characterization

    SciTech Connect

    Tsai, Y.M.; Boerio, F.J.; Kim, D.K.

    1996-12-31

    Adhesion of rubber to steel is of considerable practical importance in many areas of technology. However, direct adhesion of natural rubber to most metals is very poor. As a result, metals are frequently plated with brass, to which rubber adheres very strongly, or else the metals are coated with proprietary primers and adhesives in order to obtain adhesion of rubber. Plasma processing has been attracting attention in many areas due to some of its unique features. During the process, the synthesis and deposition of plasma polymers can be accomplished at the same time, making plasma processing a very efficient method for polymer coating. Plasma processing also allows flexible combinations of reactor parameters which would provide a great deal of process control and versatility. Moreover, in plasma processing, there are no solvents involved and there are no solvent-disposal problems. The purpose of this paper is to describe results the authors have obtained in developing plasma polymerized primer films to enhance rubber-to-steel bonding. Preliminary durability test results are reported. Results obtained using a model rubber system to simulate reactions in the rubber/primer {open_quotes}interphase{close_quotes} are also described.

  18. A study of sound absorption by street canyon boundaries and asphalt rubber concrete pavement

    NASA Astrophysics Data System (ADS)

    Drysdale, Graeme Robert

    A sound field model, based on a classical diffusion equation, is extended to account for sound absorption in a diffusion parameter used to model sound energy in a narrow street canyon. The model accounts for a single sound absorption coefficient, separate accommodation coefficients and a combination of separate absorption and accommodation coefficients from parallel canyon walls. The new expressions are compared to the original formula through numerical simulations to reveal the effect of absorption on sound diffusion. The newly established analytical formulae demonstrate satisfactory agreement with their predecessor under perfect reflection. As well, the influence of the extended diffusion parameter on normalized sound pressure levels in a narrow street canyon is in agreement with experimental data. The diffusion parameters are used to model sound energy density in a street canyon as a function of the sound absorption coefficient of the street canyon walls. The acoustic and material properties of conventional and asphalt rubber concrete (ARC) pavement are also studied to assess how the crumb rubber content influences sound absorption in street canyons. The porosity and absolute permeability of compacted specimens of asphalt rubber concrete are measured and compared to their normal and random incidence sound absorption coefficients as a function of crumb rubber content in the modified binder. Nonlinear trends are found between the sound absorption coefficients, porosity and absolute permeability of the compacted specimens and the percentage of crumb rubber in the modified binders. The cross-sectional areas of the air voids on the surfaces of the compacted specimens are measured using digital image processing techniques and a linear relationship is obtained between the average void area and crumb rubber content. The measured material properties are used to construct an empirical formula relating the average porosity, normal incidence noise reduction coefficients and

  19. Rubber lining for FGD scrubbers for waste incinerator plants

    SciTech Connect

    Rullmann, H.E.

    1999-11-01

    Flue gas desulfurization scrubbers for waste incineration plants can be lined with soft rubber or hard rubber for corrosion protection. Hard rubber is cured under high temperature and pressure in an autoclave. The advantage of hard rubber is the excellent temperature and chemical resistance. The authors have experience with hard rubber lined scrubbers that are in service without failures for over 20 years.

  20. De novo assembly and transcriptome analysis of the rubber tree (Hevea brasiliensis) and SNP markers development for rubber biosynthesis pathways.

    PubMed

    Mantello, Camila Campos; Cardoso-Silva, Claudio Benicio; da Silva, Carla Cristina; de Souza, Livia Moura; Scaloppi Junior, Erivaldo José; de Souza Gonçalves, Paulo; Vicentini, Renato; de Souza, Anete Pereira

    2014-01-01

    Hevea brasiliensis (Willd. Ex Adr. Juss.) Muell.-Arg. is the primary source of natural rubber that is native to the Amazon rainforest. The singular properties of natural rubber make it superior to and competitive with synthetic rubber for use in several applications. Here, we performed RNA sequencing (RNA-seq) of H. brasiliensis bark on the Illumina GAIIx platform, which generated 179,326,804 raw reads on the Illumina GAIIx platform. A total of 50,384 contigs that were over 400 bp in size were obtained and subjected to further analyses. A similarity search against the non-redundant (nr) protein database returned 32,018 (63%) positive BLASTx hits. The transcriptome analysis was annotated using the clusters of orthologous groups (COG), gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Pfam databases. A search for putative molecular marker was performed to identify simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs). In total, 17,927 SSRs and 404,114 SNPs were detected. Finally, we selected sequences that were identified as belonging to the mevalonate (MVA) and 2-C-methyl-D-erythritol 4-phosphate (MEP) pathways, which are involved in rubber biosynthesis, to validate the SNP markers. A total of 78 SNPs were validated in 36 genotypes of H. brasiliensis. This new dataset represents a powerful information source for rubber tree bark genes and will be an important tool for the development of microsatellites and SNP markers for use in future genetic analyses such as genetic linkage mapping, quantitative trait loci identification, investigations of linkage disequilibrium and marker-assisted selection. PMID:25048025

  1. De Novo Assembly and Transcriptome Analysis of the Rubber Tree (Hevea brasiliensis) and SNP Markers Development for Rubber Biosynthesis Pathways

    PubMed Central

    Mantello, Camila Campos; Cardoso-Silva, Claudio Benicio; da Silva, Carla Cristina; de Souza, Livia Moura; Scaloppi Junior, Erivaldo José; de Souza Gonçalves, Paulo; Vicentini, Renato; de Souza, Anete Pereira

    2014-01-01

    Hevea brasiliensis (Willd. Ex Adr. Juss.) Muell.-Arg. is the primary source of natural rubber that is native to the Amazon rainforest. The singular properties of natural rubber make it superior to and competitive with synthetic rubber for use in several applications. Here, we performed RNA sequencing (RNA-seq) of H. brasiliensis bark on the Illumina GAIIx platform, which generated 179,326,804 raw reads on the Illumina GAIIx platform. A total of 50,384 contigs that were over 400 bp in size were obtained and subjected to further analyses. A similarity search against the non-redundant (nr) protein database returned 32,018 (63%) positive BLASTx hits. The transcriptome analysis was annotated using the clusters of orthologous groups (COG), gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Pfam databases. A search for putative molecular marker was performed to identify simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs). In total, 17,927 SSRs and 404,114 SNPs were detected. Finally, we selected sequences that were identified as belonging to the mevalonate (MVA) and 2-C-methyl-D-erythritol 4-phosphate (MEP) pathways, which are involved in rubber biosynthesis, to validate the SNP markers. A total of 78 SNPs were validated in 36 genotypes of H. brasiliensis. This new dataset represents a powerful information source for rubber tree bark genes and will be an important tool for the development of microsatellites and SNP markers for use in future genetic analyses such as genetic linkage mapping, quantitative trait loci identification, investigations of linkage disequilibrium and marker-assisted selection. PMID:25048025

  2. Antimicrobial nanocomposites based on natural modified materials: a review of carbons and clays.

    PubMed

    Martynková, Grazyna Simha; Valásková, Marta

    2014-01-01

    The review is focused on the recent research and development of antimicrobial nanocomposites based on selected carbon nanomaterials and natural nanoclay minerals. The nanocomposites comprised of two or several components, where at least one presents antimicrobial properties, are discussed. Yet the most popular agent remains silver as nanoparticle or in ionic form. Second, broadly studied group, are organics as additives or polymeric matrices. Both carbons and clays in certain forms possess antimicrobial properties. A lot of interest is put on to research graphene oxide. The low-environmental impact technologies-based on sustainable biopolymers have been studied. Testing of antimicrobial properties of nanomaterials is performed most frequently on E. coli and S. aureus bacterias. PMID:24730289

  3. IR and Raman studies of oil and seedcake extracts from natural and genetically modified flax seeds

    NASA Astrophysics Data System (ADS)

    Żuk, M.; Dymińska, L.; Kulma, A.; Boba, A.; Prescha, A.; Szopa, J.; Mączka, M.; Zając, A.; Szołtysek, K.; Hanuza, J.

    2011-03-01

    Flax plant of the third generation (F3) overexpressing key genes of flavonoid pathway cultivated in field in 2008 season was used as the plant material throughout this study. The biochemical properties of seed, oil and seedcake extracts from natural and transgenic flax plants were compared. Overproduction of flavonoids (kaempferol), phenolic acids (coumaric, ferulic/synapic) and lignan-secoisolariciresinol diglucoside (SDG) in oil and extracts from transgenic seeds has been revealed providing a valuable source of these compounds for biotechnological application. The changes in fatty acids composition and increase in their stability against oxidation along three plant generations were also detected. The analysis of oil and seedcake extracts was performed using Raman and IR spectroscopy. The wavenumbers and integral intensities of Raman and IR bands were used to identify the components of phenylpropanoid pathway in oil and seedcake extracts from control and transgenic flax seeds. The spectroscopic data were compared to those obtained from biochemical analysis.

  4. Adsorption mechanism in RPLC. Effect of the nature of the organic modifier

    SciTech Connect

    Gritti, Fabrice; Guiochon, Georges A

    2005-07-01

    The adsorption isotherms of phenol and caffeine were acquired by frontal analysis on two different adsorbents, Kromasil-C{sub 18} and Discovery-C{sub 18}, with two different mobile phases, aqueous solutions of methanol (MeOH/H{sub 2}O = 40/60 and 30/70, v/v) and aqueous solutions of acetonitrile (MeCN/H{sub 2}O = 30/70 and 20/80, v/v). The adsorption isotherms are always strictly convex upward in methanol/water solutions. The calculations of the adsorption energy distribution confirm that the adsorption data for phenol are best modeled with the bi-Langmuir and the tri-Langmuir isotherm models for Kromasil-C{sub 18} and Discovery-C{sub 18}, respectively. Because its molecule is larger and excluded from the deepest sites buried in the bonded layer, the adsorption data of caffeine follow bi-Langmuir isotherm model behavior on both adsorbents. In contrast, with acetonitrile/water solutions, the adsorption data of both phenol and caffeine deviate far less from linear behavior. They were best modeled by the sum of a Langmuir and a BET isotherm models. The Langmuir term represents the adsorption of the analyte on the high-energy sites located within the C{sub 18} layers and the BET term its adsorption on the low-energy sites and its accumulation in an adsorbed multilayer system of acetonitrile on the bonded alkyl chains. The formation of a complex adsorbed phase containing up to four layers of acetonitrile (with a thickness of 3.4 {angstrom} each) was confirmed by the excess adsorption isotherm data measured for acetonitrile on Discovery-C{sub 18}. A simple interpretation of this change in the isotherm curvature at high concentrations when methanol is replaced with acetonitrile as the organic modifier is proposed, based on the structure of the interface between the C{sub 18} chains and the bulk mobile phase. This new model accounts for all the experimental observations.

  5. Assessing the effects of hydrodynamic stresses on photosynthesis with natural and modified canopy structures (Invited)

    NASA Astrophysics Data System (ADS)

    Bohrer, G.; Maurer, K.; Matheny, A.; Meyer, K.; Garrity, S. R.

    2010-12-01

    Hydraulic limitations are known to control transpiration in forest ecosystems when the soil is drying or when the vapor pressure deficit between the air and stomata (VPD) is very large, but they can also impact stomatal apertures under conditions of adequate soil moisture and lower evaporative demand. We calculated stomatal conductance from 2007-2010 using eddy-flux, meteorological and soil data at two forest sites in the University of Michigan Biological Station. We compare two sites - the Forest-Accelerated-Succession site (FASET) and its control plot, at the footprint of an Ameriflux tower. The FASET experiment simulates the transition from late-mid successional forest, dominated by tall and relatively uniform canopy of aspen and birch, to a heterogeneous late-successional mixed deciduous forest. This was done by girdling all aspen and birch trees in a 33 hectare experimental plot. The treatment occurred in 2008, and canopy structure has been drastically modified since then. The FASET canopy is, on average, shorter, more open and more heterogeneous. The Finite-Elements Tree-Crown Hydrodynamics model (FETCH), simulates water flow through the tree as a simplified system of porous media conduits. It explicitly resolves spatiotemporal hydraulic stresses throughout the tree’s hydraulic system that cannot be easily represented using other stomatal-conductance models. By enabling mechanistic simulation of the photosynthetically-equivalent costs and benefits of hydrological structural traits, FETCH modeling system enhanced our understanding of the role of hydraulic limitation on growth and for the tradeoffs between water and light in forest ecosystems. We conducted FETCH simulations using explicit branch-scale tree structures of 9 trees of 3 dominant species. By comparing the simulation results with eddy-flux observations we identified periods where stomatal conductance was lower than projected for a particular set of conditions. These periods were identified at two

  6. Thermomechanical characterisation of cellular rubber

    NASA Astrophysics Data System (ADS)

    Seibert, H.; Scheffer, T.; Diebels, S.

    2016-01-01

    This contribution discusses an experimental possibility to characterise a cellular rubber in terms of the influence of multiaxiality, rate dependency under environmental temperature and its behaviour under hydrostatic pressure. In this context, a mixed open and closed cell rubber based on an ethylene propylene diene monomer is investigated exemplarily. The present article intends to give a general idea of the characterisation method and the considerable effects of this special type of material. The main focus lies on the experimental procedure and the used testing devices in combination with the analysis methods such as true three-dimensional digital image correlation. The structural compressibility is taken into account by an approach for a material model using the Theory of Porous Media with additional temperature dependence.

  7. Removal of phosphate from aqueous solutions and sewage using natural and surface modified coir pith.

    PubMed

    Krishnan, K Anoop; Haridas, Ajit

    2008-04-01

    Iron impregnated coir pith (CP-Fe-I) can be effectively used for the removal of phosphate from aqueous streams and sewage. Iron impregnation on natural coir pith was carried out by drop by drop addition method. The effect of various factors such as pH, initial concentration of phosphate, contact time and adsorbent dose on phosphate adsorption was studied by batch technique. The pH at 3.0 favored the maximum adsorption of phosphate from aqueous solutions. The effect of pH on phosphate adsorption was explained by pH(zpc), phosphate speciation in solution and affinity of anions towards the adsorbent sites. A comparative study of the adsorption of phosphate using CP-Fe-I and CP (coir pith) was made and results show that the former one is five to six times more effective than the latter. Kinetic studies revealed that the adsorption process followed a pseudo-second order kinetic model. Adsorption followed Langmuir isotherm model. Column studies were conducted to examine the utility of the investigated adsorbent for the removal of phosphate from continuously flowing aqueous solutions. PMID:17706344

  8. Genomic Modifiers of Natural Killer Cells, Immune Responsiveness and Lymphoid Tissue Remodeling Together Increase Host Resistance to Viral Infection

    PubMed Central

    Lee, Heather; Prince, Jessica; Stadnisky, Michael D.; Anderson, Monique; Nash, William; Rival, Claudia; Wei, Hairong; Gamache, Awndre; Farber, Charles R.; Tung, Kenneth; Brown, Michael G.

    2016-01-01

    The MHC class I Dk molecule supplies vital host resistance during murine cytomegalovirus (MCMV) infection. Natural killer (NK) cells expressing the Ly49G2 inhibitory receptor, which specifically binds Dk, are required to control viral spread. The extent of Dk-dependent host resistance, however, differs significantly amongst related strains of mice, C57L and MA/My. As a result, we predicted that relatively small-effect modifier genetic loci might together shape immune cell features, NK cell reactivity, and the host immune response to MCMV. A robust Dk-dependent genetic effect, however, has so far hindered attempts to identify additional host resistance factors. Thus, we applied genomic mapping strategies and multicolor flow cytometric analysis of immune cells in naive and virus-infected hosts to identify genetic modifiers of the host immune response to MCMV. We discovered and validated many quantitative trait loci (QTL); these were mapped to at least 19 positions on 16 chromosomes. Intriguingly, one newly discovered non-MHC locus (Cmv5) controlled splenic NK cell accrual, secondary lymphoid organ structure, and lymphoid follicle development during MCMV infection. We infer that Cmv5 aids host resistance to MCMV infection by expanding NK cells needed to preserve and protect essential tissue structural elements, to enhance lymphoid remodeling and to increase viral clearance in spleen. PMID:26845690

  9. Modified natural porcine surfactant inhibits superoxide anions and proinflammatory mediators released by resting and stimulated human monocytes.

    PubMed

    Walti, H; Polla, B S; Bachelet, M

    1997-01-01

    Pulmonary surfactant has a potential role in modulating inflammation in normal and injured lungs. In lung injury, monocytes become activated and participate in lung inflammation. We therefore, investigated the proinflammatory functions of stimulated human blood monocytes after an overnight preincubation period with modified natural porcine surfactant (Curosurf) (500-1000 micrograms/mL). Monocytes were stimulated either with phorbol myristate acetate (PMA), bacterial extract OM-85, lipopolysaccharide (LPS), or Ca2+ ionophore A23187. The present study shows that Curosurf significantly inhibits: 1) the production of superoxide anions stimulated with OM-85 (1 mg/mL, 30 min), but not with PMA (100 ng/mL, 30 min); 2) the release of cyclooxygenase metabolites prostaglandin E2 and thromboxane B2 stimulated with OM-85 (1 mg/mL, overnight); 3) the release of lipoxygenase metabolite leukotriene C4 stimulated with A23187 (10 microM, 10 min); 4) the release of the cytokine TNF-alpha stimulated overnight with either OM-85 (1 mg/mL) or LPS (10 micrograms/mL)) in a dose-dependent fashion. In addition, Curosurf decreases the spontaneous adherence of monocytes to plastic culture wells in a dose-dependent fashion. Experiments performed with staurosporine, an inhibitor of protein kinase C (PKC) indicate that, in contrast with PMA, the production of superoxide anions stimulated by OM-85 is not related to PKC activation. Consequently, we propose that the mechanism involved in the suppressive effects of Curosurf is PKC-independent. In summary, the present study provides experimental evidence that favors the anti-inflammatory role of modified natural porcine surfactant (Curosurf) in human monocytes in vitro. PMID:8979299

  10. Blow molding of melt processible rubber

    SciTech Connect

    Abell, W.R.; Stuart, R.E.; Myrick, R.E.

    1991-07-01

    This article discusses the advantages of making hollow rubber parts by blow molding thermoplastic elastomers (TPEs) versus conventional rubber processing. It describes the various types of blow molding processes and it provides some insight into the rheological properties of melt processible rubber (MPR) and how MPR should be molded by each of these processes. A number of blow molded applications for MPR are also discussed.

  11. Surgical rubber gloves impervious to methylmethacrylate monomer.

    PubMed

    Darre, E; Vedel, P

    1984-06-01

    Conventional surgical rubber gloves are permeable to the methylmethacrylate monomer (MMM) of acrylic bone cement. An in vitro technique was used which proved butyl rubber gloves, 0.48 mm thick, to be impervious to MMM. to avoid sensitization, butyl rubber gloves may be recommended to persons who are in contact with MMM. Such gloves should be worn by persons with known contact sensitization to MMM. PMID:6741470

  12. Rubber friction: comparison of theory with experiment.

    PubMed

    Lorenz, B; Persson, B N J; Dieluweit, S; Tada, T

    2011-12-01

    We have measured the friction force acting on a rubber block slid on a concrete surface. We used both unfilled and filled (with carbon black) styrene butadiene (SB) rubber and have varied the temperature from -10 °C to 100 °C and the sliding velocity from 1 μm/s to 1000 μm/s. We find that the experimental data at different temperatures can be shifted into a smooth master-curve, using the temperature-frequency shifting factors obtained from measurements of the bulk viscoelastic modulus. The experimental data has been analyzed using a theory which takes into account the contributions to the friction from both the substrate asperity-induced viscoelastic deformations of the rubber, and from shearing the area of real contact. For filled SB rubber the frictional shear stress σ(f) in the area of real contact results mainly from the energy dissipation at the opening crack on the exit side of the rubber-asperity contact regions. For unfilled rubber we instead attribute σ(f) to shearing of a thin rubber smear film, which is deposited on the concrete surface during run in. We observe very different rubber wear processes for filled and unfilled SB rubber, which is consistent with the different frictional processes. Thus, the wear of filled SB rubber results in micrometer-sized rubber particles which accumulate as dry dust, which is easily removed by blowing air on the concrete surface. This wear process seams to occur at a steady rate. For unfilled rubber a smear film forms on the concrete surface, which cannot be removed even using a high-pressure air stream. In this case the wear rate appears to slow down after some run in time period. PMID:22139094

  13. SOURCE ASSESSMENT: RUBBER PROCESSING, STATE OF THE ART

    EPA Science Inventory

    This report summarizes data on air emissions from the production of vulcanized elastomers (rubbers) and fabrication of rubber products. Hydrocarbons and particulates are emitted from various operations. Hydrocarbon emissions consist of monomers, rubber chemicals, and solvents whi...

  14. Recycling rubber wastes. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    1995-02-01

    The bibliography contains citations concerning research and innovations in the recycling of rubber wastes. Recycling methods and equipment, applications of recycled rubber, and energy recovery systems and performance are among the topics discussed. Recycling methods compared and contrasted with various rubber waste disposal techniques are also included. (Contains a minimum of 96 citations and includes a subject term index and title list.)

  15. Recycling rubber wastes. (Latest citations from the rubber and plastics research association database). Published Search

    SciTech Connect

    Not Available

    1994-05-01

    The bibliography contains citations concerning research and innovations in the recycling of rubber wastes. Recycling methods and equipment, applications of recycled rubber, and energy recovery systems and performance are among the topics discussed. Recycling methods compared and contrasted with various rubber waste disposal techniques are also included. (Contains a minimum of 89 citations and includes a subject term index and title list.)

  16. Method for the addition of vulcanized waste rubber to virgin rubber products

    DOEpatents

    Romine, R.A.; Snowden-Swan, L.J.

    1997-01-28

    The invention is a method of using enzymes from thiophyllic microbes for selectively breaking the sulfur rubber cross-link bonds in vulcanized rubber. The process is halted at the sulfoxide or sulfone step so that a devulcanized layer is reactive with virgin rubber. 8 figs.

  17. Method for the addition of vulcanized waste rubber to virgin rubber products

    DOEpatents

    Romine, Robert A.; Snowden-Swan, Lesley J.

    1997-01-01

    The invention is a method of using enzymes from thiophyllic microbes for selectively breaking the sulfur rubber cross-link bonds in vulcanized rubber. The process is halted at the sulfoxide or sulfone step so that a devulcanized layer is reactive with virgin rubber.

  18. Risk and Control of Mosquito-Borne Diseases in Southeast Asian Rubber Plantations.

    PubMed

    Tangena, Julie-Anne A; Thammavong, Phoutmany; Wilson, Anne L; Brey, Paul T; Lindsay, Steve W

    2016-05-01

    Unprecedented economic growth in Southeast Asia (SEA) has encouraged the expansion of rubber plantations. This land-use transformation is changing the risk of mosquito-borne diseases. Mature plantations provide ideal habitats for the mosquito vectors of malaria, dengue, and chikungunya. Migrant workers may introduce pathogens into plantation areas, most worryingly artemisinin-resistant malaria parasites. The close proximity of rubber plantations to natural forest also increases the threat from zoonoses, where new vector-borne pathogens spill over from wild animals into humans. There is therefore an urgent need to scale up vector control and access to health care for rubber workers. This requires an intersectoral approach with strong collaboration between the health sector, rubber industry, and local communities. PMID:26907494

  19. Preparation and characterizations of activated carbon monolith from rubber wood and its effect on supercapacitor performances

    NASA Astrophysics Data System (ADS)

    Taer, E.; Taslim, R.; Deraman, M.

    2016-02-01

    Preparation of activated carbon monolith (ACM) from rubber wood was investigated. Two kind of preparation method were carried out by pre-carbonized of rubber wood saw dust and rubber wood material as it is naturally. The samples were prepared with pelletizing method and small cutting of rubber wood in cross sectional method. Both of samples were characterized by physical and electrochemical technique. The physical properties such as morphology and porosity were investigated. The electrochemical properties of both samples such as equivalent series resistances (ESR) and specific capacitances were also compared. In conclusion, this study showed that both of different preparation method would propose a simple method of ACM electrode preparation technique for supercapacitor applications.

  20. Conductivity of natural and modified DNA measured by scanning tunneling microscopy. The effect of sequence, charge and stacking.

    PubMed

    Kratochvílová, Irena; Král, Karel; Buncek, Martin; Vísková, Alena; Nespůrek, Stanislav; Kochalska, Anna; Todorciuc, Tatiana; Weiter, Martin; Schneider, Bohdan

    2008-11-01

    The conductivity of DNA covalently bonded to a gold surface was studied by means of the STM technique. Various single- and double-stranded 32-nucleotide-long DNA sequences were measured under ambient conditions so as to provide a better understanding of the complex process of charge-carrier transport in natural as well as chemically modified DNA molecules. The investigations focused on the role of several features of DNA structure, namely the role of the negative charge at the backbone phosphate group and the related complex effects of counterions, and of the stacking interactions between the bases in Watson-Crick and other types of base pairs. The measurements have indicated that the best conductor is DNA in its biologically most relevant double-stranded form with Watson-Crick base pairs and charged phosphates equilibrated with counterions and water. All the studied modifications, including DNA with non-Watson-Crick base pairs, the abasic form, and especially the form with phosphate charges eliminated by chemical modifications, lower the conductivity of natural DNA. PMID:18801607

  1. Microwave induced fast pyrolysis of scrap rubber tires

    NASA Astrophysics Data System (ADS)

    Ani, Farid Nasir; Mat Nor, Nor Syarizan

    2012-06-01

    Pyrolysis is the thermal degradation of carbonaceous solid by heat in the absence of oxygen. The feedstocks, such as biomass or solid wastes are heated to a temperature between 400 and 600°C, without introducing oxygen to support the reaction. The reaction produces three products: gas, pyro-fuel oil and char. This paper presents the techniques of producing pyro-oil from waste tires, as well as investigation of the fuel properties suitable for diesel engine applications. In this study, microwave heating technique is employed to pyrolyse the used rubber tires into pyro-oil. Thermal treatment of as received used rubber tires is carried out in a modified domestic microwave heated fixed bed technology. It has been found that, rubber tires, previously used by various researchers, are poor microwave absorbers. Studies have shown that an appropriate microwave-absorbing material, such as biomass char or activated carbon, could be added to enhance the pyrolysis process; thus producing the pyro-oil. The characteristics of pyro-oil, as well as the effect of microwave absorber on its yield, are briefly described in this paper. The temperature profiles during the microwave heating process are also illustratively emphasized. The study provides a means of converting scrap tires into pyro-oil and pyrolytic carbon black production. The proposed microwave thermal conversion process therefore has the potentials of substantially saving time and energy.

  2. Photocatalytic degradation of phenol in natural seawater using visible light active carbon modified (CM)-n-TiO2 nanoparticles under UV light and natural sunlight illuminations.

    PubMed

    Shaban, Yasser A; El Sayed, Mohamed A; El Maradny, Amr A; Al Farawati, Radwan Kh; Al Zobidi, Mousa I

    2013-04-01

    The photocatalytic degradation of phenol in seawater was investigated under UV and natural sunlight using visible light active carbon modified (CM)-n-TiO2 nanoparticles, synthesized via a sol-gel method. Carbon modification of n-TiO2 was performed using titanium butoxide, carbon-containing precursor, as a source of both carbon and titanium. For comparison, unmodified n-TiO2 was also synthesized by hydrolysis and oxidation of titanium trichloride in the absence of any carbon source. The presence of carbon in CM-n-TiO2 nanoparticles was confirmed by energy dispersive spectroscopy (EDS) analysis. Carbon modification was found to be responsible for lowering the bandgap energy from 3.14eV for n-TiO2 to 1.86eV for CM-n-TiO2 which in turn enhanced the photocatalytic activity of CM-n-TiO2 towards the degradation of phenol in seawater under illumination of UV light as well as natural sunlight. This enhanced photoresponse of CM-n-TiO2 is in agreement with the UV-Vis spectroscopic results that showed higher absorption of light in both UV and visible regions. The effects of catalyst dose, initial concentration of phenol, and pH were studied. The highest degradation rate was obtained at pH 3 and catalyst dose of 1.0gL(-1). The data photocatalytic degradation of phenol in seawater using CM-n-TiO2 were successfully fitted to Langmuir-Hinshelwood model, and can be described by pseudo-first order kinetics. PMID:23261126

  3. RUBBER-PROCESSING CHEMICALS DATA BASE

    EPA Science Inventory

    The objective of this research program was to compile a data base covering all the commercially significant organic rubber-processing chemicals produced or imported in the United States. The Rubber-Processing Chemicals Data Base contains the following elements: chemical informati...

  4. Roughness Perception during the Rubber Hand Illusion

    ERIC Educational Resources Information Center

    Schutz-Bosbach, Simone; Tausche, Peggy; Weiss, Carmen

    2009-01-01

    Watching a rubber hand being stroked by a paintbrush while feeling identical stroking of one's own occluded hand can create a compelling illusion that the seen hand becomes part of one's own body. It has been suggested that this so-called rubber hand illusion (RHI) does not simply reflect a bottom-up multisensory integration process but that the…

  5. 75 FR 38119 - Polychloroprene Rubber From Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-01

    ... from Japan (38 FR 33593). Following five-year reviews by the Department of Commerce (``Commerce'') and... imports of polychloroprene rubber from Japan (64 FR 47765, September 1, 1999). Following second five-year... antidumping duty finding on imports of polychloroprene rubber from Japan (70 FR 44893). The Commission is...

  6. 75 FR 57980 - Polychloroprene Rubber From Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-23

    ... interested parties did not participate in this sunset review * * *.'' (75 FR 51981). Accordingly, pursuant to... COMMISSION Polychloroprene Rubber From Japan AGENCY: United States International Trade Commission. ACTION... whether revocation of the antidumping duty finding on polychloroprene rubber from Japan would be likely...

  7. Zinc leaching from tire crumb rubber.

    PubMed

    Rhodes, Emily P; Ren, Zhiyong; Mays, David C

    2012-12-01

    Because tires contain approximately 1-2% zinc by weight, zinc leaching is an environmental concern associated with civil engineering applications of tire crumb rubber. An assessment of zinc leaching data from 14 studies in the published literature indicates that increasing zinc leaching is associated with lower pH and longer leaching times, but the data display a wide range of zinc concentrations, and do not address the effect of crumb rubber size or the dynamics of zinc leaching during flow through porous crumb rubber. The present study was undertaken to investigate the effect of crumb rubber size using the synthetic precipitation leaching procedure (SPLP), the effect of exposure time using quiescent batch leaching tests, and the dynamics of zinc leaching using column tests. Results indicate that zinc leaching from tire crumb rubber increases with smaller crumb rubber and longer exposure time. Results from SPLP and quiescent batch leaching tests are interpreted with a single-parameter leaching model that predicts a constant rate of zinc leaching up to 96 h. Breakthrough curves from column tests displayed an initial pulse of elevated zinc concentration (~3 mg/L) before settling down to a steady-state value (~0.2 mg/L), and were modeled with the software package HYDRUS-1D. Washing crumb rubber reduces this initial pulse but does not change the steady-state value. No leaching experiment significantly reduced the reservoir of zinc in the crumb rubber. PMID:23145882

  8. RADIATION INDUCED VULCANIZATION OF RUBBER LATEX

    DOEpatents

    Mesrobian, R.B.; Ballantine, D.S.; Metz, D.J.

    1964-04-28

    A method of vulcanizing rubber latex by exposing a mixture containing rubber latex and from about 15 to about 21.3 wt% of 2,5-dichlorostyrene to about 1.1 megarads of gamma radiation while maintaining the temperature of the mixture at a temperature ranging between from about 56 to about 59 deg C is described. (AEC)

  9. Cotton-Fiber-Filled Rubber Insulation

    NASA Technical Reports Server (NTRS)

    Anderson, Floyd A.

    1987-01-01

    Carbonization of fibers at high temperatures improves strength and erosion resistance. Cotton linters tested as replacement for asbestos filler currently used in rubber insulation in solid rocket motors. Cotton-filled rubber insulation has industrial uses; in some kinds of chemical- or metal-processing equipment, hoses, and protective clothing.

  10. Rubber elasticity: From topology to filled elastomers

    SciTech Connect

    Heinrich, G.; Vilgis, T.A.

    1993-12-31

    Various new aspects in the elasticity of rubbers and statistics of unfilled and filled elastomers, together with various consequences for practical application are discussed. It is shown that the role of network topology is crucial in the statistics of rubbers. This is seen mostly on the influence of heterogeneities of crosslink density which determine the elastic modulus, ultimate properties as well as the dynamical behavior. The filler effects, entanglements in filled rubbers, and the filler/bound rubber/mobile rubber problem are discussed from a novel point of view. A localization model is adopted, where it can be shown that on a rough (filler) surface more polymer can be adsorbed compared to a flat surface with similar energetic properties. The role of carbon black networking and fractal properties of the filler are discussed in relation to the dynamic-mechanical properties of the elastomer.

  11. Replacing rubber plantations by rain forest in Southwest China--who would gain and how much?

    PubMed

    Ahlheim, Michael; Börger, Tobias; Frör, Oliver

    2015-02-01

    The cultivation of rubber trees in Xishuangbanna Prefecture in China's Yunnan Province has triggered an unprecedented economic development but it is also associated with severe environmental problems. Rubber plantations are encroaching the indigenous rain forests at a large scale and a high speed in Xishuangbanna. Many rare plant and animal species are endangered by this development, the natural water management is disturbed, and even the microclimate in this region has changed over the past years. The present study aims at an assessment of the environmental benefits accruing from a reforestation project partly reversing the deforestation that has taken place over the past years. To this end, a Contingent Valuation survey has been conducted in Xishuangbanna to elicit local residents' willingness to pay for this reforestation program that converts existing rubber plantations back into forest. It is shown that local people's awareness of the environmental problems caused by increasing rubber plantation is quite high and that in spite of the economic advantages of rubber plantation there is a positive willingness among the local population to contribute financially to a reduction of existing rubber plantations for the sake of a partial restoration of the local rain forest. These results could be used for the practical implementation of a Payments for Eco-System Services system for reforestation in Xishuangbanna. PMID:25604061

  12. [Destruction of the solid-cast rubber tyres by microscopic fungi].

    PubMed

    Chuienko, A I; Subbota, A H; Zhdanova, N M

    2010-01-01

    Resistance to the action of standard test-cultures of fungi (in accordance with GOST 9.049-91 of the former U.S.S.R.) and species, isolated from rubber substrates of two types of the poured rubber tyres, which contained natural and synthetic plasticizer, have been investigated. It has been shown that the strains, isolated from rubber materials have an ability to deteriorate rubber tyres of two types, in contrast to standard species, which caused deterioration only to the tyres, containing the synthetic plasticizer. It has been described in our investigations that fungal resistance of studied tyres decrease with time (on the 28th and 365th day, accordingly), that is shown in full overgrowing of tyre samples, in destruction of their surfaces and in changing of their hardness. Such changes are accompanied by processes of oxidation of rubber, degradation of plasticizer, and by deleaching of such inorganic components of rubber as calcium carbonate, kaolin and zeolite. This information is presented on IR-spectrograms of investigated samples as the absence or presence of absorption frequencies of different intensity that corresponded to aromatic, hydroxyl, ester, alcohol, nitrile and inorganic groups. The paper is presented in Ukrainian. PMID:21117295

  13. Improving dyeability of modified cotton fabrics by the natural aqueous extract from red cabbage using ultrasonic energy.

    PubMed

    Ben Ticha, Manel; Haddar, Wafa; Meksi, Nizar; Guesmi, Ahlem; Mhenni, M Farouk

    2016-12-10

    The concern regarding sustainable utilization of available resources is growing due to its global importance. In this paper, the dyeability of cotton fabrics with natural colorant extracted from red cabbage was improved by applying cationic groups on cotton fibers. Modification of cotton was carried using acid tannic, Rewin Os, Denitex BC and Sera Fast as cationic agents. The dyeing process was done by ultrasonic energy. The effects of the cationising agent amount, the dye bath pH, the dyeing temperature and duration, on the sonicator dyeing quality were studied. The performances of this process were evaluated by measuring the colour yield (K/S) and the dyeing fastness of the coloured cotton. Besides, modified cotton fibers were characterized by morphology analysis (SEM) and Fourier transform infrared (FTIR) spectra and compared to untreated cotton. Moreover, a two-level full factorial design was employed to optimize the sonicator dyeing process. Mathematical model equation and statistical analysis were derived by computer simulation programming applying the least squares method using Minitab 15. Best dyeing conditions were found to be: 10%, pH 11, 60min and 100°C respectively for the Sera Fast amount, dye bath pH, dyeing duration and temperature. PMID:27577920

  14. Bio-Templated Growth of Bone Minerals from Modified Simulated Body Fluid on Nanofibrous Decellularized Natural Tissues.

    PubMed

    Yang, Mingying; Wang, Jie; Zhu, Ye; Mao, Chuanbin

    2016-04-01

    Small intestine submucosal (SIS) membrane used in this study is a decellularized, naturally occurring nanofibrous scaffold derived from a submucosal layer of porcine small intestine. It is predominantly composed of type I collagen fibers. Here we studied the bio-templated growth of hydroxylapatite (HAP) bone minerals on the SIS membrane from a modified simulated body fluid (1.5 SBF) at the body temperature, namely, under a near-physiological condition, in order to evaluate its bone bioactivity, the capability of the membrane in bonding with bone tissue once implanted in vivo. Minute HAP crystals were successfully nucleated on the SIS membranes from 1.5 SBF at the body temperature. The crystals were preferentially nucleated along the collagen fibers constituting the SIS membranes. HAP was the major crystalline mineral phase formed during the whole period of time and a minor crystalline phase of tricalcium phosphate (TCP) appeared after the membranes were incubated for 96 h. We also found that the mineralization for 8 h most significantly promoted the osteogenic differentiation of rat mesenchymal stem cells (MSCs) by evaluating the formation of osteogenic markers in MSCs including alkaline phosphatase (early stage marker) as well as osteocalcin and osteopontin (late stage markers). Hence, SIS membranes show excellent bone bioactivity and once mineralized, can significantly promote the osteogenic differentiation of MSCs. PMID:27301201

  15. Natural convection of non-Newtonian fluid along a vertical thin cylinder using modified power-law model

    NASA Astrophysics Data System (ADS)

    Thohura, Sharaban; Molla, Md. Mamun; Sarker, M. M. A.

    2016-07-01

    A study on the natural convection flow of non-Newtonian fluid along a vertical thin cylinder with constant wall temperature using modified power law viscosity model has been done. The basic equations are transformed to non dimensional boundary layer equations and the resulting systems of nonlinear partial differential equations are then solved employing marching order implicit finite difference method. The evolution of the surface shear stress in terms of local skin-friction, the rate of heat transfer in terms of local Nusselt number, velocity and temperature profiles for shear thinning as well as shear-thickening fluid considering the different values of Prandtl number have been focused. For the Newtonian fluids the present numerical results are compared with available published results which show a good agreement indeed. From the results it can be concluded that, at the leading edge, a Newtonian-like solution exists as the shear rate is not large enough to trigger non-Newtonian effects. Non-Newtonian effects can be found when the shear-rate increases beyond a threshold value.

  16. Quantitative rubber sheet models of gravitation wells using Spandex

    NASA Astrophysics Data System (ADS)

    White, Gary

    2008-04-01

    Long a staple of introductory treatments of general relativity, the rubber sheet model exhibits Wheeler's concise summary---``Matter tells space-time how to curve and space-time tells matter how to move''---very nicely. But what of the quantitative aspects of the rubber sheet model: how far can the analogy be pushed? We show^1 that when a mass M is suspended from the center of an otherwise unstretched elastic sheet affixed to a circular boundary it exhibits a distortion far from the center given by h = A*(M*r^2)^1/3 . Here, as might be expected, h and r are the vertical and axial distances from the center, but this result is not the expected logarithmic form of 2-D solutions to LaPlace's equation (the stretched drumhead). This surprise has a natural explanation and is confirmed experimentally with Spandex as the medium, and its consequences for general rubber sheet models are pursued. ^1``The shape of `the Spandex' and orbits upon its surface'', American Journal of Physics, 70, 48-52 (2002), G. D. White and M. Walker. See also the comment by Don S. Lemons and T. C. Lipscombe, also in AJP, 70, 1056-1058 (2002).

  17. History of Rubber and Its Use

    NASA Astrophysics Data System (ADS)

    Müller, Ingo; Strehlow, Peter

    Despite its spectacular properties rubber was not much good for anything before the latter part of the 19th century. To be sure the Aztecs had used it to make balls for their ceremonial ball games - or so we are told. But those games died along with the Aztec culture in the 16th century and there is no record of other useful applications until the late 18th century. But then, after that, rubber took off in a small way. After the American inventor Samuel Peal had obtained a patent in 1791 for the production of rubber-coated watertight textiles, the Scottish chemist Charles Macintosh (1766-1843) used such textiles for making rain-coats, and Thomas Hancock (1786-1865) produced rubber boots. At that time it was not really appropriate to speak of a rubber industry. What little material the evil-smelling workshops in New York and London needed, could be satisfied with the import of 30 tons of Caoutchouc1 annually - extracted from the sap of the tree Hevea brasiliensis - and most of that went for making erasers. Indeed, it had been reported by the English minister and scientist Joseph Priestley (1733-1804) that pieces of rubber are well-suited to rub out (sic!) pencil marks. Even today there is nothing better for the purpose and rubber became the English word for Caoutchouc.

  18. Hyundai plans rubber unit despite overcapacity

    SciTech Connect

    Hyoungjin Kim

    1993-02-24

    Despite the oversupply of synthetic rubber in South Korea, the government has granted approval to Hyundai Petrochemical (Seoul) to build the country's second synthetic rubber unit, to be located alongside its petrochemical complex at Daesan. The plant is due for startup during second-half 1995, when the local market is expected to be in better balance. Hyundai will use Goodyear Tire Rubber technology for the plant, which will have annual capacities for 40,000 m.t. of polybutadiene rubber (BR), 30,000 m.t. of styrene butadiene rubber (SBR) and 12,000 m.t. of nitrile rubber (NBR). Styrene and butadiene requirements will be met from Hyundai's own production at Daesan. The current local producer of synthetic rubber is Korea Kumho Petrochemicals (Seoul), which has annual capacities for 150,000 m.t. of SBR, 95,000 m.t. of BR, and 10,000 m.t. of NBR. Korean SBR demand is about 141,000 m.t./year but is expected to increase to 161,000 m.t./year by 1996 and reach 194,000 m.t./year by the end of the decade.

  19. Zinc Leaching from Tire Crumb Rubber

    NASA Astrophysics Data System (ADS)

    Rhodes, E. P.; Ren, J.; Mays, D. C.

    2010-12-01

    Recent estimates indicate that more than 2 billion scrap tires are currently stockpiled in the United States and approximately 280 million more tires are added annually. Various engineering applications utilize recycled tires in the form of shredded tire crumb rubber. However, the use of tire crumb rubber may have negative environmental impacts, especially when the rubber comes into contact with water. A review of the literature indicates that leaching of zinc from tire crumb rubber is the most significant water quality concern associated with using this material. Zinc is generally used in tire manufacturing, representing approximately 1.3% of the final product by mass. This study will report results from the U.S. Environmental Protection Agency’s (EPA’s) Synthetic Precipitation Leaching Procedure, batch leaching tests, and column leaching tests performed to quantify the process by which zinc leaches from tire crumb rubber into water. Results are interpreted with a first-order kinetic attachment/detachment model, implemented with the U.S. Agricultural Research Service software HYDRUS-1D, in order to determine the circumstances when zinc leaching from tire crumb rubber would be expected to comply with the applicable discharge limits. One potential application for recycled tires is replacing sand with tire crumb rubber in granular media filters used for stormwater pollution control. For this to be a viable application, the total zinc in the stormwater discharge must be below the EPA’s benchmark value of 0.117 mg/L.

  20. Molecular evolution and functional characterisation of haplotypes of an important rubber biosynthesis gene in Hevea brasiliensis.

    PubMed

    Uthup, T K; Rajamani, A; Ravindran, M; Saha, T

    2016-07-01

    Hydroxy-methylglutaryl coenzyme-A synthase (HMGS) is a rate-limiting enzyme in the cytoplasmic isoprenoid biosynthesis pathway leading to natural rubber production in Hevea brasiliensis (rubber). Analysis of the structural variants of this gene is imperative to understand their functional significance in rubber biosynthesis so that they can be properly utilised for ongoing crop improvement programmes in Hevea. We report here allele richness and diversity of the HMGS gene in selected popular rubber clones. Haplotypes consisting of single nucleotide polymorphisms (SNPs) from the coding and non-coding regions with a high degree of heterozygosity were identified. Segregation and linkage disequilibrium analysis confirmed that recombination is the major contributor to the generation of allelic diversity, rather than point mutations. The evolutionarily conserved nature of some SNPs was identified by comparative DNA sequence analysis of HMGS orthologues from diverse taxa, demonstrating the molecular evolution of rubber biosynthesis genes in general. In silico three-dimensional structural studies highlighting the structural positioning of non-synonymous SNPs from different HMGS haplotypes revealed that the ligand-binding site on the enzyme remains impervious to the reported sequence variations. In contrast, gene expression results indicated the possibility of association between specific haplotypes and HMGS expression in Hevea clones, which may have a downstream impact up to the level of rubber production. Moreover, haplotype diversity of the HMGS gene and its putative association with gene expression can be the basis for further genetic association studies in rubber. Furthermore, the data also show the role of SNPs in the evolution of candidate genes coding for functional traits in plants. PMID:26787454