Friction characteristics of 20 x 4.4, type 7, aircraft tires constructed with different tread rubber compounds

NASA Technical Reports Server (NTRS)

Dreher, R. C.; Yager, T. J.

1976-01-01

A test program was conducted at the Langley aircraft landing loads and traction facility to evaluate the friction characteristics of 20 x 4.4, type, aircraft tires constructed with experimental cut-resistant, tread rubber compounds. These compounds consisted of different blends of natural rubber (NR) and an alfin catalyzed styrene-butadiene copolymer rubber (SBR). One tire having a blend of 30 SBR and 70 NR and another having a blend of 60 SBR and 40 NR in the tread were tested together with a standard production tire with no SBR content in the tread rubber. The results of this investigation indicated that the test tires constructed with the special cut-resistant tread rubber compositions did not suffer any significant degradation in tire friction capability when compared with the standard tire. In general, tire friction capability decreased with increasing speed and surface wetness condition. As yaw angle increased, tire braking capability decreased while tire cornering capability increased. Tread-wear data based on number of brake cycles, however, suggested that the tires with alfin SBR blends experienced significantly greater wear than the standard production tire.

Replacement Packing for 37MM Antitank Gun Recoil

DTIC Science & Technology

2008-04-01

Parts Per Hundred Rubber (PPHR) NBR -07-GRS-01 Paracril AJ Nitrile Rubber 100.00 Zinc Oxide 5.00 Stearic Acid 1.00 AC) 617 Polyethylene 2.00 (DQ...3 Figure 4. Nitrile rubber compound being produced on rolling mill. ..............................................5 Figure 5. The two...9 List of Tables Table 1. Composition and properties of Nitrile rubber ...................................................................4

Dental Assistant, Advanced. Revision

DTIC Science & Technology

1989-02-01

compound , or model- ing plaster instead of the rubber dam retainer Removing the Rubber Dam (figures 4-4 and 4-5). A ligature can also be used After the...roots or split crowns. If a is checked. When directed by the dental officer, ligature, dental compound , or modeling plaster remove the rubber dam...34clean" and 1 " dirty " JOB STEPS 1. Wash hands. 2. Recor! patient’s name. 3. Explain procedure to patient. 4. Tell patient to lie in bed or be seated

Comparative studies on crosslinked and uncrosslinked natural rubber biodegradation by Pseudomonas sp.

PubMed

Roy, Ram Vinod; Das, Mithu; Banerjee, Rintu; Bhowmick, Anil K

2006-12-01

A comparative study on biodegradation of di-cumyl peroxide (DCP) crosslinked and uncrosslinked natural rubber by Pseudomonas sp. was carried out. Decrease in organic carbon content along with the changes in tensile strength of the treated rubber, both DCP crosslinked and uncrosslinked natural rubber, indicated rubber hydrocarbon utilization by the Pseudomonas sp. A decrease in 60.88% MPa and 41.66% MPa was observed after five month's old treated uncrosslinked natural rubber and DCP crosslinked rubber, respectively. Biodegradation was more pronounced in natural uncrosslinked rubber, which was further confirmed by the formation of aldehydic compounds with decrease in CH2 stretching frequencies.

Polyether precursors of molecular recognition systems based on the 9,10-anthraquinone moiety

NASA Astrophysics Data System (ADS)

Wcisło, Anna; Cirocka, Anna; Zarzeczańska, Dorota; Niedziałkowski, Paweł; Nakonieczna, Sandra; Ossowski, Tadeusz

2015-02-01

A series of novel polyether derivatives of 9,10-anthraquinone (AQ) was synthesized and characterized by means of UV-Vis spectroscopy, acid-base titration and complexometric titration. The results were compared with 1-NEt2AQ and 1-NHEtAQ - model compounds of alkylaminoanthraquinones. Acetonitrile and methanol were used as solvents for determination of spectroscopic and acid-base properties. Complexometric titrations were carried out exclusively in acetonitrile. Spectral characteristic of these compounds strongly depends on pH. Addition of acid causes the decrease of absorption intensity and in some cases also a shift of the visible range band. The weakest base is the compound (2), and the strongest - compound (1), both in methanol and acetonitrile solution. The introduction of an additional substituent in the position 8 of the anthraquinone compound increases its basicity. The presence of metal ions causes changes in intensity of absorption (decrease for compounds (2) and (3) and increase with bathochromic shift for (1) and (4)). For the determination of the coordination properties aluminum (III) ions were chosen. The highest complex stability constant with Al (III) ions is observed for compound (1), and the weakest for compound (3). The elongation of the polyether chain decreases the stability of the complex formed.

Polyether precursors of molecular recognition systems based on the 9,10-anthraquinone moiety.

PubMed

Wcisło, Anna; Cirocka, Anna; Zarzeczańska, Dorota; Niedziałkowski, Paweł; Nakonieczna, Sandra; Ossowski, Tadeusz

2015-02-25

A series of novel polyether derivatives of 9,10-anthraquinone (AQ) was synthesized and characterized by means of UV-Vis spectroscopy, acid-base titration and complexometric titration. The results were compared with 1-NEt2AQ and 1-NHEtAQ--model compounds of alkylaminoanthraquinones. Acetonitrile and methanol were used as solvents for determination of spectroscopic and acid-base properties. Complexometric titrations were carried out exclusively in acetonitrile. Spectral characteristic of these compounds strongly depends on pH. Addition of acid causes the decrease of absorption intensity and in some cases also a shift of the visible range band. The weakest base is the compound (2), and the strongest--compound (1), both in methanol and acetonitrile solution. The introduction of an additional substituent in the position 8 of the anthraquinone compound increases its basicity. The presence of metal ions causes changes in intensity of absorption (decrease for compounds (2) and (3) and increase with bathochromic shift for (1) and (4)). For the determination of the coordination properties aluminum (III) ions were chosen. The highest complex stability constant with Al (III) ions is observed for compound (1), and the weakest for compound (3). The elongation of the polyether chain decreases the stability of the complex formed. Copyright © 2014 Elsevier B.V. All rights reserved.

Occupational exposure to rubber vulcanization products during repair of rubber conveyor belts in a brown coal mine.

PubMed

Gromiec, Jan P; Wesołowski, Wiktor; Brzeźnicki, Sławomir; Wróblewska-Jakubowska, Krystyna; Kucharska, Małgorzata

2002-12-01

Several hundred chemical compounds were found in workroom environments in the rubber industry, but most of the published exposure data relate to the production of tyres; information from the "non-tyre" sections are very limited, if any. This study was carried out to identify chemical substances and measure their air concentrations in the repair shop of a brown coal mine in which damaged rubber conveyor belts were repaired. GC-MS and HPLC analysis of stationary air samples resulted in identification of aliphatic and aromatic hydrocarbons to C12, PAHs, alcohols, phenols, ketones, heterocyclic nitrogen and sulfur compounds. Quantitative evaluation of occupational exposure included determination of organic compound vapours collected on charcoal (GC-MSD), polycyclic aromatic hydrocarbons (HPLC), N-nitrosoamines and other amines (GC-NPD) and DNPH derivatives of aldehydes (HPLC) in the breathing zone of workers representing all job titles. The concentrations of investigated compounds were very low. Carcinogenic substances: N-nitrosoamines, benzene, PAHs were not present in workroom air in concentrations exceeding limits of detection of the analytical methods being applied; concentrations of methylisobutylketone, tetrachloroethylene, naphtha, aromatic hydrocarbons, phthalates and aldehydes were much lower than the respective occupational exposure limit values. The results indicate much lower exposure than that reported in the production of tyres and other fabricated rubber products.

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 mechanism.

Determination of priority and other hazardous substances in football fields of synthetic turf by gas chromatography-mass spectrometry: A health and environmental concern.

PubMed

Celeiro, Maria; Dagnac, Thierry; Llompart, Maria

2018-03-01

Due to the high concern generated in the last years about the safety of recycled tire rubber used for recreational sports surfaces, this study aims at evaluating the presence of forty organic compounds including polycyclic aromatic hydrocarbons (PAHs), phthalates, adipates, vulcanisation additives and antioxidants in recycled tire crumb of synthetic turf football fields. Ultrasound Assisted Extraction (UAE) was successfully employed to extract the target compounds from the crumb rubber, and analysis was performed by gas chromatography-mass spectrometry (GC-MS). The transfer of the target chemicals from the crumb rubber to the runoff water and to the air above the rubber surface has also been evaluated employing solid-phase microextraction (SPME). Samples from fifteen football fields were analysed, and the results revealed the presence of 24 of the 40 target compounds, including 14 of the 16 EPA PAHs, with total concentrations up to 50 μg g -1 . Heavy metals such as Cd, Cr and Pb were also found. A partial transfer of organic compounds to the air and runoff water was also demonstrated. The analysis of rain water collected directly from the football field, showed the presence of a high number of the target compounds at concentrations reaching above 100 μg L -1 . The environmental risk arising from the burning of crumb rubber tires has been assessed, as well, analysing the crumb rubber, and the air and water in contact with this material, showing a substantial increase both of the number and concentration of the hazardous chemicals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Adhesion and friction between glass and rubber in the dry state and in water: role of contact hydrophobicity.

PubMed

Kawasaki, S; Tada, T; Persson, B N J

2018-06-27

We study the contact mechanics between 3 different tire tread compounds and a smooth glass surface in water. We study both adhesion and sliding friction at low-sliding speeds. For 2 of the compounds the rubber-glass contact in water is hydrophobic and we observe adhesion, and slip-stick sliding friction dynamics. For one compound the contact is hydrophilic, resulting in vanishing adhesion, and steady-state (or smooth) sliding dynamics. We also show the importance of dynamical scrape, both on the macroscopic level and at the asperity level, which reduces the water film thickness between the solids during slip. The experiments show that the fluid is removed much faster from the rubber-glass asperity contact regions for a hydrophobic contact than for a hydrophilic contact. We also study friction on sandblasted glass in water. In this case all the compounds behave similarly and we conclude that no dewetting occur in the asperity contact regions. We propose that this is due to the increased surface roughness which reduces the rubber-glass binding energy.

Finite element simulation and experimental verification of steel cord extraction of steel cord conveyor belt splice

NASA Astrophysics Data System (ADS)

Li, X. G.; Long, X. Y.; Jiang, H. Q.; Long, H. B.

2018-05-01

The splice is the weakest part of the entire steel cord conveyor belt. And it occurs steel cord twitch fault frequently. If this fault cannot be dealt with timely and accurately, broken belt accidents would be occurred that affecting the safety of production seriously. In this paper, we investigate the steel cord pullout of the steel cord conveyor belt splice by using ABAQUS software. We selected the strength of steel cord conveyor belt ST630, the same as experiment sample in type specification. The finite element model consists of rubber, steel cord and failure unit. And the failure unit is used to simulate the bonding relationship between the steel cord and the rubber. Mooney-Rivlin hyper-elastic model for rubber was employed in the numerical simulations. The pullout force of length 50.0 mm single steel cord, on both sides of a single steel cord and on both sides of the double steel cords each impacted at steel cord conveyor belt splice were numerically computer and typical results obtained have been validated by experimental result. It shows that the relative error between simulation results and experimental results is within 10% and can be considered that the simulation model is reliable. A new method is provided for studying the steel cord twitch fault of the steel cord conveyor belt splice.

[Total analysis of organic rubber additives].

PubMed

He, Wen-Xuan; Robert, Shanks; You, Ye-Ming

2010-03-01

In the present paper, after middle pressure chromatograph separation using both positive phase and reversed-phase conditions, the organic additives in ethylene-propylene rubber were identified by infrared spectrometer. At the same time, by using solid phase extraction column to maintain the main component-fuel oil in organic additves to avoid its interfering with minor compounds, other organic additves were separated and analysed by GC/Ms. In addition, the remaining active compound such as benzoyl peroxide was identified by CC/Ms, through analyzing acetone extract directly. Using the above mentioned techniques, soften agents (fuel oil, plant oil and phthalte), curing agent (benzoylperoxide), vulcanizing accelerators (2-mercaptobenzothiazole, ethyl thiuram and butyl thiuram), and antiagers (2, 6-Di-tert-butyl-4-methyl phenol and styrenated phenol) in ethylene-propylene rubber were identified. Although the technique was established in ethylene-propylene rubber system, it can be used in other rubber system.

Deuterium permeation through EPDM rubber compounds

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

Zapp, P.E.

1988-01-01

The permeation of deuterium through a specially formulated compound of ethylene propylene diene rubber was measured in the temperature range of 26/degree/C to 120/degree/C. The results were similar to permeation through two commercial compounds of this elastomer. Permeation was reduced after gamma irradiation (in the presence of hydrogen gas to simulate a tritium exposure). However the reduction was smaller than that experienced by the two commercial compounds. Radiation damage is apparently less severe in the special compound. It is possible that mechanical properties such as compression set may be influenced less by ionizing radiation in this compound as compared withmore » the commercial compounds. 4 figs., 1 tab.« less

49 CFR 179.201-3 - Lined tanks.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.201-3 Lined tanks. (a) Rubber... the service temperatures. (b) Before a tank car tank is lined with rubber, or other rubber compound, a... suitable for the service temperatures. (f) Polyvinyl chloride lined tanks. Tank car tanks or each...

Study on small molecular organic compounds pyrolysed from rubber seed oil and its sodium soap.

PubMed

Fernando, T L D; Prashantha, M A B; Amarasinghe, A D U S

2016-01-01

Rubber seed oil (RSO) and its sodium soap were pyrolysed in a batch reactor to obtain low molar mass organic substances. The pyrolitic oil of RSO was redistilled and the distillates were characterized by GC-MS and FTIR. Density, acid value, saponification value and ester values were also measured according to the ASTM standard methods. A similar analysis was done for samples taken out at different time intervals from the reaction mixture. Industrially important low molar mass alkanes, alkenes, aromatics, cyclic compounds and carboxylic acids were identified in the pyrolysis process of rubber seed oil. However, pyrolysis of the sodium soap of rubber seed oil gave a mixture of hydrocarbons in the range of C14-C17 and hence it has more applications as a fuel.

Development of Improved Rubber Compounds for Use in Weapon Applications

DTIC Science & Technology

1974-08-01

temperature properties, oil resistance or resistance to aging were noted for the Japanese elastomers. Rubber For Use In Liquid Propellants Results of a...gun systems. However. EPDM . Hydrln. Butyl EPRVxton an3 Nitroso rubbers were indicated as likely choices. Vulc.nlzates based on the last three of... rubber already in use. An EPDM vulcanizate, Nordel 1070, could be used in liquid propeliant gun systans in which hydrazine is used as an oxidizer

Study on a Haptic Sensor Using MCF (Magnetic Compound Fluid) Electric Conductive Rubber

NASA Astrophysics Data System (ADS)

Zheng, Yaoyang; Shimada, Kunio

To provide a new composite material having a high degree of sensitivity regarding both electrical conduction and temperature for the field of robotics or sensing, we have developed magnetic rubber that contains a network-like magnetic cluster. We compared the temperature response of MCF rubber with others rubbers made under various experimental conditions, allowing us to find an optimum condition for making MCF rubber. The temperature response was obtained by an experimental equation. We also compared the electric conductivity of MCF rubber with that of ordinary electric conductive rubber and found that its electric sensitivity was lower at a small deformation, but increased at larger deformations. Therefore, MCF rubber has proven itself effective as a switching sensor when a small deformation is applied.

Research on a haptic sensor made using MCF conductive rubber

NASA Astrophysics Data System (ADS)

Zheng, Yaoyang; Shimada, Kunio

2008-05-01

To provide a new composite material having a high electrical sensitivity in the fields of robotics and sensing, a magnetic rubber having network-like magnetic clusters was developed by utilizing a magnetic compound fluid (MCF). MCF rubber with small deformations can provide an effective sensor. In this paper, we report many experiments in which changes of the MCF rubber's resistance were observed when the rubber was compressed and a deformation was generated; we then made a trial haptic sensor using the MCF conductive rubber and performed many experiments to observe changes of the electrical resistance of the sensor. The results of experiments showed that the proposed sensor made with MCF conductive rubber is useful for sensing small amounts of pressure or small deformations.

Research on a haptic sensor made using MCF conductive rubber.

PubMed

Zheng, Yaoyang; Shimada, Kunio

2008-05-21

To provide a new composite material having a high electrical sensitivity in the fields of robotics and sensing, a magnetic rubber having network-like magnetic clusters was developed by utilizing a magnetic compound fluid (MCF). MCF rubber with small deformations can provide an effective sensor. In this paper, we report many experiments in which changes of the MCF rubber's resistance were observed when the rubber was compressed and a deformation was generated; we then made a trial haptic sensor using the MCF conductive rubber and performed many experiments to observe changes of the electrical resistance of the sensor. The results of experiments showed that the proposed sensor made with MCF conductive rubber is useful for sensing small amounts of pressure or small deformations.

Microbial detoxification of waste rubber material by wood-rotting fungi.

PubMed

Bredberg, Katarina; Andersson, B Erik; Landfors, Eva; Holst, Olle

2002-07-01

The extensive use of rubber products, mainly tires, and the difficulties to recycle those products, has resulted in world wide environmental problems. Microbial devulcanisation is a promising way to increase the recycling of rubber materials. One obstacle is that several microorganisms tested for devulcanisation are sensitive to rubber additives. A way to overcome this might be to detoxify the rubber material with fungi prior to the devulcanisation. In this study, 15 species of white-rot and brown-rot fungi have been screened with regard to their capacity to degrade an aromatic model compound in the presence of ground waste tire rubber. The most effective fungus, Resinicium bicolor, was used for detoxification of rubber material. Increase in growth of the desulfurising bacterium Thiobacillus ferrooxidans in presence of the rubber treated with Resinicium bicolor compared to untreated rubber demonstrated that detoxification with fungi is possible.

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

New sulfenamide accelerators derived from 'safe' amines for the rubber and tyre industry.

PubMed

Wacker, C D; Spiegelhalder, B; Preussmann, R

1991-01-01

A reduction of the high exposures to N-nitrosamines in the rubber and tyre industry is possible using the concept of 'safe' amines, in which vulcanization accelerators contain amine moieties that are both difficult to nitrosate and, on nitrosation, yield noncarcinogenic N-nitroso compounds. The toxicological and technological properties of more than 50 benzothiazole sulfenamides derived from 'safe' amines have been evaluated. Some of the new compounds show excellent vulcanization properties and seem suitable as replacements for traditional accelerators in this class of compounds.

Rubber friction on road surfaces: Experiment and theory for low sliding speeds

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

Lorenz, B.; Persson, B. N. J.; Oh, Y. R.

We study rubber friction for tire tread compounds on asphalt road surfaces. The road surface topographies are measured using a stylus instrument and atomic force microscopy, and the surface roughness power spectra are calculated. The rubber viscoelastic modulus mastercurves are obtained from dynamic mechanical analysis measurements and the large-strain effective modulus is obtained from strain sweep data. The rubber friction is measured at different temperatures and sliding velocities, and is compared to the calculated data obtained using the Persson contact mechanics theory. We conclude that in addition to the viscoelastic deformations of the rubber surface by the road asperities, theremore » is an important contribution to the rubber friction from shear processes in the area of contact. The analysis shows that the latter contribution may arise from rubber molecules (or patches of rubber) undergoing bonding-stretching-debonding cycles as discussed in a classic paper by Schallamach.« less

Structural characterization of rubber from jackfruit and euphorbia as a model of natural rubber.

PubMed

Mekkriengkrai, Dararat; Ute, Koiichi; Swiezewska, Ewa; Chojnacki, Tadeusz; Tanaka, Yasuyuki; Sakdapipanich, Jitladda T

2004-01-01

A structural study of low molecular weight rubbers from Jackfruit (Artocarpus heterophyllus) and Painted spurge (Euphorbia heterophylla) was carried out as model compounds of natural rubber from Hevea brasiliensis. The rubber content of latex from Jackfruit was 0.4-0.7%, which is very low compared with that of 30-35% in the latex from Hevea tree. The rubber from Jackfruit latex was low molecular weight with narrow unimodal molecular weight distribution (MWD), whereas that obtained from E. heterophylla showed very broad MWD. The 1H and 13C NMR analyses showed that Jackfruit rubber consists of a dimethylallyl group and two trans-isoprene units connected to a long sequence of cis-isoprene units. The alpha-terminal group of Jackfruit rubber was presumed to be composed of a phosphate group based on the presence of 1H NMR signal at 4.08 ppm corresponding to the terminal =CH-CH2OP group.

Development of Bushing Compounds for Tracked Vehicles

DTIC Science & Technology

1990-10-01

unwanted stepchild - part of called anti patented NBR -12 formulation the family (system), but devoid of needed indicated that service life could be...as Development and Engineering Center’s long. Bushings currently used in the M I track Rubber and Coated Fabrics Research Group assembly typically fail...formulations of should be improved. Numerous selected candidate natural rubber , propylene formulations-based on natural rubber , oxide, and silicone

A green procedure using ozone for Cleaning-in-Place in the beverage industry.

PubMed

Nishijima, Wataru; Okuda, Tetsuji; Nakai, Satoshi; Okada, Mitsumasa

2014-06-01

Cleaning-in-Place (CIP) in the beverage industry is typically carried out in production lines with alkaline and acidic solutions with detergents. This cleaning not only produces alkaline and acidic wastewater with detergents but also takes significant time. One of the important targets for CIP is adsorbed odorous compounds on gaskets, hence, we have tried to establish a rapid and green CIP process to remove traces of such compounds, especially d-limonene, an odorous component of orange juice, using two approaches; an ozone cleaning method and a change of gasket material from ethylene propylene diene monomer (EPDM) rubber to silicone rubber. By changing the gasket material from EPDM rubber to silicone rubber, the removability of d-limonene by typical alkaline and acidic cleanings with detergents was improved. However, complete removal of 4 mg g(-1) of d-limonene on both EPDM and silicone gaskets could not be achieved even using a series of conventional cleaning procedures that included alkaline and acidic cleaning for 220 min. Ozone treatment dramatically improved the removability of d-limonene, removing 87% from the EPDM gasket at 60 min and 100% from the silicone gasket at 30 min. The combination of the silicone gasket and ozone treatment resulted in the most effective cleaning. The main removal mechanism for ozone treatment was confirmed to be oxidation by molecular ozone. Effectiveness of changing the gasket material from EPDM rubber to silicone rubber in reducing residual amounts of odorous compounds adsorbed on the gaskets was also confirmed for furfural and 4-vinylguaiacol. Copyright © 2014 Elsevier Ltd. All rights reserved.

Towards development of lignin reinforced elastomeric compounds with reduced energy dissipation

NASA Astrophysics Data System (ADS)

Bahl, Kushal

This research deals with development of lignin as reinforcing filler for elastomeric compounds. Lignins are naturally abundant and cost competitive wood derivatives possessing strong mechanical properties and offering reactive functional groups on their surfaces. The presence of the functional groups imparts polarity to the lignin molecules and makes them incompatible with non-polar elastomers. Also, the large particle size of lignin does not produce desired mechanical reinforcement. The present study deals with solving the outstanding issues associated with the use of lignin as fillers for polymeric compounds. In addition, the work specifically focuses on producing rubber compounds with reduced energy dissipation via partial replacement of carbon black with lignin. The first part of this study is devoted to suppression of the polarity of lignin and achievement of compatibility with rubber matrix via modification of lignosulfonates (LS) with cyclohexylamine (CA). CA reduces the polarity of lignin via interactions originating from proton transfer and hydrogen bonding. X-ray Photoelectron Spectroscopy (XPS) confirms the attachment of CA on the surfaces of lignin. The mechanical properties of rubber compounds increase substantially along with improvement in cure properties and increase in crosslink density in the presence of LS particles modified with CA. The tensile strength and storage modulus show an increase by 45% and 41% respectively. The values of the 100% modulus and elongation at break also improve by 35% and 60% respectively. The second part of this study exploits the non-covalent interactions between lignin and carbon black (CB) for the design of novel hybrid filler particles exhibiting lower energy loss in rubber compounds. The hybrid fillers offer unique morphology consisting of coating layers of lignin on carbon black particle aggregates. It is found that such coating layers are formed due to pi-pi interactions between lignin and carbon black. Raman spectroscopy and 1H spin-lattice relaxation times confirm pi-pi interactions. The hybrid fillers offer reduction of networking of carbon black particles and viscoelastic dissipation in rubber compounds without sacrificing the mechanical performance. The third part of this study evaluates the performance of polybutadiene- g-polypentafluorostyrene (PB-g-PPFS) as a coupling agent for promotion of interactions between lignin and rubber and to achieve better overall reinforcing performance. The PB domains of PB-g-PPFS are compatible with styrene-butadiene rubber (SBR) while the PPFS segments engage in arene-perfluoroarene interactions with lignin. These interactions are confirmed via UV-vis spectroscopy data. The efficacy of PB-g-PPFS as a coupling agent is evaluated for compounds filled with lignin and lignin/carbon black hybrid fillers. The results show that the addition of PB-g-PPFS improves the tensile strength by 33% and reduces the viscoelastic loss in filled SBR compounds by improving filler dispersion. The results presented in this thesis demonstrate that the approaches of surface modification, exploitation of non-covalent interactions, and the use of coupling agents are effective in solving the impending issues associated with the use of lignin, the second most abundant bio-derived material, as effective reinforcing filler for polymer compounds.

Degree of Mechanochemical Devulcanization of Model Styrene-Butadiene Rubber Compounds Containing Different Amount of Poly-, Di- and Monosulphidic Bonds

NASA Astrophysics Data System (ADS)

Sangari, Samra; Anita, Hill; Dumitru, Pavel

2004-03-01

There have been significant attempts to devulcanize waste elastomers to facilitate reusing these valuable resources in applications requiring the unique properties of rubber. The difficulty in recycling of elastomers has traditionally been with devulcanizing the elastomer without comprising its properties due to degradation of main chains. This research aimed to devulcanize model styrene-butadiene rubber (SBR) compounds, which had various amounts of poly-, di- and monosulfidic crosslinks using a mechanochemical process. Three model compounds were prepared using SBR using a laboratory two-roll mill. They were then vulcanized in a compression molding press at 140r C. The prepared vulcanized compounds were then ground and devulcanized in an internal mixer using a chemical mixture at a constant rotor speed and temperature. The crosslink density of the compounds before and after the devulcanization was calculated using volume-swelling measurements. The obtained data was used to establish the correlation between crosslink density of the compounds and the degree of devulcanization. The results showed that mechanochemical devulcanization caused a significant decrease in the crosslink density of the compounds by breaking the sulfidic linkages. The break up of polysulfidic crosslinks was predominant, meaning that mechanochemical process selectively affected different types of crosslinks.

Cure characteristics, crosslink density and degree of filler dispersion of kaolin-filled natural rubber compounds in the presence of alkanolamide

NASA Astrophysics Data System (ADS)

Surya, I.; Hayeemasae, N.; Ginting, M.

2018-03-01

The effects of alkanolamide (ALK) addition on cure characteristics, crosslink density and degree of filler dispersion of kaolin-filled natural rubber (NR) compounds were investigated. The kaolin filler was incorporated into NR compounds with a fixed loading, 30.0 phr. The ALK was prepared from Refined Bleached Deodorized Palm Stearin (RBDPS), a waste product of cooking oil production, and diethanolamine. The ALK is an oily material and added into the filled NR compounds as a rubber additive at different loadings, 0.0, 3.0, 5.0 and 7.0. The kaolin-filled NR compounds with and without ALK were vulcanized using a semi-efficient vulcanization system. It was found that ALK decreased the scorch and cure times and improved filler dispersion of the kaolin-filled NR compounds. The higher the ALK loading, the shorter were the scorch and cure times. It was also found that ALK increased the crosslink density of kaolin-filled NR compound up to 5.0 phr of loading. Due to its oily properties, The ALK acted as an internal plasticizer which decreased the minimum torque and improved the degree of kaolin dispersion in NR phases. The higher the ALK loading; the lower the minimum torque and better the filler dispersion.

The Effect of Particles on Electrolytically Polymerized Thin Natural MCF Rubber for Soft Sensors Installed in Artificial Skin.

PubMed

Shimada, Kunio; Mochizuki, Osamu; Kubota, Yoshihiro

2017-04-19

The aim of this study is to investigate the effect of particles as filler in soft rubber sensors installed in artificial skin. We examine sensors made of natural rubber (NR-latex) that include magnetic particles of Ni and Fe₃O₄ using magnetic compound fluid (MCF). The 1-mm thickness of the electrolytically polymerized MCF rubber makes production of comparatively thin rubber sensors feasible. We first investigate the effect of magnetic particles Ni and Fe₃O₄ on the curing of MCF rubber. Next, in order to adjust the electric properties of the MCF rubber, we adopt Al₂O₃ dielectric particles. We investigate the effect of Al₂O₃ particles on changes in electric current, voltage and temperature of electrolytically polymerized MCF rubber liquid, and on the electric properties under the application of normal and shear forces. By adjusting the ratio of Ni, Fe₃O₄, Al₂O₃ and water in MCF rubber with Al₂O₃, it is possible to change the electric properties.

Health aspects of the curing of synthetic rubbers.

PubMed Central

Fraser, D A; Rappaport, S

1976-01-01

A commonly used tread rubber formulation was cured in the laboratory under conditions simulating vulcanization in the Bag-O-Matic press. Volatile emissions were collected on charcoal and analyzed by combined GC-mass spectrometry. The compounds identified were either contaminants present in the raw material or reaction products. Some of these compounds were also identified in charcoal tube samples collected in the atmosphere of the industrial operations. Estimates based on the loss of weight of rubber during curing were used to predict airborne concentrations and compared to the concentrations actually found. The literature of the toxicity of raw materials and effluents was reviewed, and no acute or chronic toxicological effects would be anticipated. Information concerning potential carcinogenicity was not available and could not be evaluated. PMID:1026417

Leaching of zinc compound from rubber stoppers into the contents of automatic atropine injectors.

PubMed

Ellin, R I; Kaminskis, A; Zvirblis, P; Sultan, W E; Shutz, M B; Matthews, R

1985-07-01

This report describes how a material within the cartridge of an automatic injector contaminated its contents. On prolonged storage, a formulation that contained atropine produced lethality in mice. The toxic material originated from zinc compounds that were present in the rubber stopper and plunger of the container and that subsequently leached into the formulation. The contents of cartridges that contained greater than or equal to 0.75 mg/mL of solubilized zinc were lethal to at least 20% of the mice tested; those that contained 0.42 mg/mL showed no lethality. The problem resulted from the physicochemical properties of the rubber, not the concentration of zinc used in the vulcanization process.

Morphology and thermal stability of nano titanium dioxide filled natural rubber prepared by latex mixing method

NASA Astrophysics Data System (ADS)

Hayeemasae, N.; Surya, I.; Ismail, H.

2018-02-01

This paper deals with the morphology and thermal stability of nano Titanium Dioxide (TiO2) filled natural rubber composites. This study also suggests a new method of incorporating TiO2. Aqueous dispersions of nano TiO2at the loadings of 0, 2, 4, 6 and 8 phr were dispersed in natural rubber latex, the resulting compounds were then dried prior to mixing it with other ingredients on a two-roll mill. By applying this technique, the homogeneity of the compound is significantly improved. This can be clearly seen from the morphology observed. Adding TiO2 results in shifting the decomposition temperature and char residue irrespective of the loadings of nano TiO2.

Study on cord/rubber interface at elevated temperatures by H-pull test method

NASA Astrophysics Data System (ADS)

Jamshidi, M.; Afshar, F.; Mohammadi, N.; Pourmahdian, S.

2005-08-01

Cords are used as reinforcing materials in rubber compounds. To increase cord/rubber interfacial adhesion, they are coated by an adhesive (usually based on resorcinol-formaldehyde-latex). These composites are used in many sectors such as tire and belt industries. Cord/rubber adhesion strength is an important aspect to determine the durability of system. Due to temperature increase during running tires, the adhesion energy becomes different from initial one. To study cord/rubber interface at elevated temperatures, H-adhesion test method was used. H-pull test is a simple method for adhesion evaluation at ambient temperature, so it is usually used for material quality control. In this research, cord/rubber systems were vulcanized at different temperatures and H-adhesion of samples were evaluated at elevated temperatures. Also cord/rubber interface was studied by ATR analyze to determine interfacial interactions kind.

The effect of filler on the protein content and interferences in rubber latices

NASA Astrophysics Data System (ADS)

Ruhida, A. R.; Hassan, Aziz

2017-12-01

It is well known that the application of commercial fillers like calcium carbonate has widely been used in natural rubber latex (NRL) gloves as well as other dipped products such as balloons, condom and catheters. The main reason of adding the fillers into the rubber compound was as cheapening aid and to improve the end-product properties. Due to its functional benefit, many studies have been conducted on the application and beneficial usage of fillers in natural rubber (NR) compounds and natural rubber latex (NRL) dipped goods namely gloves. However most of the studies were basically emphasizing on the effect of fillers on the physical properties and surface morphology of rubber. Not many studies have been conducted to investigate the effect of filler on the protein content in NRL products. Earlier work by other workers has only been concentrating on the effect of nano-sized calcium carbonate fillers in NR latex gloves. Because of the concern on the issue of latex protein allergy; it is thus important to study the effect of filler on protein content and its interferences in the rubber lattices. This paper will seek to elaborate on the effect of filler content on the total protein and extractable protein (EP) content of NR latex films at various filler loadings before and after ageing. The effect of interferences by filler that was mixed into the NR latex on the total nitrogen and EP content were also measured and shown.

Industrial waste treatment and application in rubber production

NASA Astrophysics Data System (ADS)

Pugacheva, I. N.; Popova, L. V.; Repin, P. S.; Molokanova, L. V.

2018-03-01

The paper provides for the relevance of various industrial waste treatment and application, as well as their secondary commercialization. It considers treatment of secondary polymer materials turning to additives applied in rubber production, in particular, in production of conveyor and V-type belts used in mechanical engineering. It is found that oligomers obtained from petroleum by-products can be used as an impregnating compound for fiber materials. Such adhesive treatment prior to introduction of impregnating compounds into elastomeric materials improves adhesion and complements performance of obtained composites.

The Effect of Particles on Electrolytically Polymerized Thin Natural MCF Rubber for Soft Sensors Installed in Artificial Skin

PubMed Central

Shimada, Kunio; Mochizuki, Osamu; Kubota, Yoshihiro

2017-01-01

The aim of this study is to investigate the effect of particles as filler in soft rubber sensors installed in artificial skin. We examine sensors made of natural rubber (NR-latex) that include magnetic particles of Ni and Fe3O4 using magnetic compound fluid (MCF). The 1-mm thickness of the electrolytically polymerized MCF rubber makes production of comparatively thin rubber sensors feasible. We first investigate the effect of magnetic particles Ni and Fe3O4 on the curing of MCF rubber. Next, in order to adjust the electric properties of the MCF rubber, we adopt Al2O3 dielectric particles. We investigate the effect of Al2O3 particles on changes in electric current, voltage and temperature of electrolytically polymerized MCF rubber liquid, and on the electric properties under the application of normal and shear forces. By adjusting the ratio of Ni, Fe3O4, Al2O3 and water in MCF rubber with Al2O3, it is possible to change the electric properties. PMID:28422061

Effects of alkanolamide loading on swelling, rheometric and tensile properties of chloroprene rubber compounds

NASA Astrophysics Data System (ADS)

Surya, I.; Ismail, H.

2018-02-01

The effects of Alkanolamide (ALK) addition on swelling, rheometric and tensile properties of unfilled chloroprene rubber (CR) compounds were investigated. The ALK was prepared from Refined Bleached Deodorized Palm Stearin and diethanolamine and -together with magnesium and zinc oxides- incorporated into the CR compounds. The ALK loadings were 0.5, 1.0, 1.5 and 2.0 phr. It was found that ALK enhanced the cure rate and torque difference of the CR compounds. ALK also enhanced the tensile modulus and tensile strength; especially up to a 1.5 phr loading. The swelling test proved that the 1.5 phr of ALK exhibited the highest degree of crosslink density which caused the highest in tensile modulus and tensile strength.

Standard Rubbers for Chemical Defense Research. Volume 1. Formulation and Properties

DTIC Science & Technology

1989-01-01

by the military services. There is a growing need to determine the susceptibility of diese materials to the chemical threats anticipated from the...leading to a very weak signal which contains little spectral information. An alternative method involves very rapid pyrolysis of the rubber specimen to...After nitrogen gas purge of the pyrolysis cell, a small chunk of the rubber compound was heated at 600’C for 60 seconds by use of a Foxboro Pyro

Acute toxicity of leachates of tire wear material to Daphnia magna--variability and toxic components.

PubMed

Wik, Anna; Dave, Göran

2006-09-01

Large amounts of tire rubber are deposited along the roads due to tread wear. Several compounds may leach from the rubber and cause toxicity to aquatic organisms. To investigate the toxic effects of tire wear material from different tires, rubber was abraded from the treads of twenty-five tires. Leachates were prepared by allowing the rubber to equilibrate with dilution water at 44 degrees C for 72 h. Then the rubber was filtered from the leachates, and test organisms (Daphnia magna) were added. Forty-eight hour EC50s ranged from 0.5 to >10.0 g l(-1). The toxicity identification evaluation (TIE) indicated that non-polar organic compounds caused most of the toxicity. UV exposure of the filtered tire leachates caused no significant increase in toxicity. However, when tested as unfiltered leachates (the rubber was not filtered from the leachates before addition of D. magna) photo-enhanced toxicity was considerable for some tires, which means that test procedures are important when testing tire leachates for aquatic (photo) toxicity. The acute toxicity of tire wear for Daphnia magna was found to be <40 times a predicted environmental concentration based on reports on the concentration of a tire component found in environmental samples, which emphasizes the need for a more extensive risk assessment of tire wear for the environment.

40 CFR 428.71 - Specialized definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Fabricated Rubber Plants Subcategory § 428.71 Specialized definitions. For the purpose of this subpart: (a... natural and synthetic rubber, carbon black, oils, chemical compounds, and fabric used in the manufacture... divided by the total volume of air scrubbed. (d) The term “large-sized plants” shall mean plants which...

40 CFR 428.71 - Specialized definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., Extruded, and Fabricated Rubber Plants Subcategory § 428.71 Specialized definitions. For the purpose of...” shall mean all natural and synthetic rubber, carbon black, oils, chemical compounds, and fabric used in... wet scrubbers divided by the total volume of air scrubbed. (d) The term “large-sized plants” shall...

40 CFR 428.51 - Specialized definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Fabricated Rubber Plants Subcategory § 428.51 Specialized definitions. For the purpose of this subpart: (a... natural and synthetic rubber, carbon black, oils, chemical compounds, and fabric used in the manufacture... divided by the total volume of air scrubbed. (d) The term “small-sized plants” shall mean plants which...

40 CFR 428.51 - Specialized definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., Extruded, and Fabricated Rubber Plants Subcategory § 428.51 Specialized definitions. For the purpose of...” shall mean all natural and synthetic rubber, carbon black, oils, chemical compounds, and fabric used in... wet scrubbers divided by the total volume of air scrubbed. (d) The term “small-sized plants” shall...

40 CFR 428.51 - Specialized definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Fabricated Rubber Plants Subcategory § 428.51 Specialized definitions. For the purpose of this subpart: (a... natural and synthetic rubber, carbon black, oils, chemical compounds, and fabric used in the manufacture... divided by the total volume of air scrubbed. (d) The term “small-sized plants” shall mean plants which...

40 CFR 428.61 - Specialized definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Fabricated Rubber Plants Subcategory § 428.61 Specialized definitions. For the purpose of this subpart: (a... natural and synthetic rubber, carbon black, oils, chemical compounds, and fabric used in the manufacture... divided by the total volume of air scrubbed. (d) The term “medium-sized plants” shall mean plants which...

40 CFR 428.51 - Specialized definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., Extruded, and Fabricated Rubber Plants Subcategory § 428.51 Specialized definitions. For the purpose of...” shall mean all natural and synthetic rubber, carbon black, oils, chemical compounds, and fabric used in... wet scrubbers divided by the total volume of air scrubbed. (d) The term “small-sized plants” shall...

40 CFR 428.61 - Specialized definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., Extruded, and Fabricated Rubber Plants Subcategory § 428.61 Specialized definitions. For the purpose of...” shall mean all natural and synthetic rubber, carbon black, oils, chemical compounds, and fabric used in... wet scrubbers divided by the total volume of air scrubbed. (d) The term “medium-sized plants” shall...

40 CFR 428.51 - Specialized definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., Extruded, and Fabricated Rubber Plants Subcategory § 428.51 Specialized definitions. For the purpose of...” shall mean all natural and synthetic rubber, carbon black, oils, chemical compounds, and fabric used in... wet scrubbers divided by the total volume of air scrubbed. (d) The term “small-sized plants” shall...

40 CFR 428.61 - Specialized definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., Extruded, and Fabricated Rubber Plants Subcategory § 428.61 Specialized definitions. For the purpose of...” shall mean all natural and synthetic rubber, carbon black, oils, chemical compounds, and fabric used in... wet scrubbers divided by the total volume of air scrubbed. (d) The term “medium-sized plants” shall...

40 CFR 428.71 - Specialized definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., Extruded, and Fabricated Rubber Plants Subcategory § 428.71 Specialized definitions. For the purpose of...” shall mean all natural and synthetic rubber, carbon black, oils, chemical compounds, and fabric used in... wet scrubbers divided by the total volume of air scrubbed. (d) The term “large-sized plants” shall...

40 CFR 428.71 - Specialized definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., Extruded, and Fabricated Rubber Plants Subcategory § 428.71 Specialized definitions. For the purpose of...” shall mean all natural and synthetic rubber, carbon black, oils, chemical compounds, and fabric used in... wet scrubbers divided by the total volume of air scrubbed. (d) The term “large-sized plants” shall...

40 CFR 428.61 - Specialized definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., Extruded, and Fabricated Rubber Plants Subcategory § 428.61 Specialized definitions. For the purpose of...” shall mean all natural and synthetic rubber, carbon black, oils, chemical compounds, and fabric used in... wet scrubbers divided by the total volume of air scrubbed. (d) The term “medium-sized plants” shall...

40 CFR 428.61 - Specialized definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Fabricated Rubber Plants Subcategory § 428.61 Specialized definitions. For the purpose of this subpart: (a... natural and synthetic rubber, carbon black, oils, chemical compounds, and fabric used in the manufacture... divided by the total volume of air scrubbed. (d) The term “medium-sized plants” shall mean plants which...

40 CFR 428.71 - Specialized definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Fabricated Rubber Plants Subcategory § 428.71 Specialized definitions. For the purpose of this subpart: (a... natural and synthetic rubber, carbon black, oils, chemical compounds, and fabric used in the manufacture... divided by the total volume of air scrubbed. (d) The term “large-sized plants” shall mean plants which...

Elastic MCF Rubber with Photovoltaics and Sensing on Hybrid Skin (H-Skin) for Artificial Skin by Utilizing Natural Rubber: Third Report on Electric Charge and Storage under Tension and Compression †.

PubMed

Shimada, Kunio

2018-06-06

In the series of studies on new types of elastic and compressible artificial skins with hybrid sensing functions, photovoltaics, and battery, we have proposed a hybrid skin (H-Skin) by utilizing an electrolytically polymerized magnetic compound fluid (MCF) made of natural rubber latex (NR-latex). By using the experimental results in the first and second reports, we have clarified the feasibility of electric charge at irradiation, and that without illumination under compression and elongation. The former was explained in a wet-type MCF rubber solar cell by developing a tunneling theory together with an equivalent electric circuit model. The latter corresponds to the battery rather than to the solar cell. As for the MCF rubber battery, depending on the selected agent type, we can make the MCF rubber have higher electricity and lighter weight. Therefore, the MCF rubber has an electric charge and storage whether at irradiation or not.

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.

40 CFR 710.4 - Scope of the inventory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... upon use of curable plastic or rubber molding compounds, inks, drying oils, metal finishing compounds... impart a specific physicochemical characteristic, functions as intended. (8) Chemical substances which...

40 CFR 710.4 - Scope of the inventory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... modifier, pH neutralizer, sequesterant, coagulant, flocculant, fire retardant, lubricant, chelating agent... upon use of curable plastic or rubber molding compounds, inks, drying oils, metal finishing compounds...

Determination of silicone rubber and low-density polyethylene diffusion and polymer/water partition coefficients for emerging contaminants.

PubMed

Pintado-Herrera, Marina G; Lara-Martín, Pablo A; González-Mazo, Eduardo; Allan, Ian J

2016-09-01

There is a growing interest in assessing the concentration and distribution of new nonregulated organic compounds (emerging contaminants) in the environment. The measurement of freely dissolved concentrations using conventional approaches is challenging because of the low concentrations that may be encountered and their temporally variable emissions. Absorption-based passive sampling enables the estimation of freely dissolved concentrations of hydrophobic contaminants of emerging concern in water. In the present study, calibration was undertaken for 2 polymers, low-density polyethylene (LDPE) and silicone rubber for 11 fragrances, 5 endocrine-disrupting compounds, 7 ultraviolet (UV) filters, and 8 organophosphate flame retardant compounds. Batch experiments were performed to estimate contaminant diffusion coefficients in the polymers (Dp ), which in general decreased with increasing molecular weight. The values for fragrances, endocrine-disrupting compounds, and UV filters were in ranges similar to those previously reported for polycyclic aromatic hydrocarbons, but were 1 order of magnitude lower for organophosphate flame retardant compounds. Silicone rubber had higher Dp values than LDPE and was therefore selected for further experiments to calculate polymer/water partition coefficients (KPW ). The authors observed a positive correlation between log KPW and log octanol/water partition coefficient values. Field testing of silicone rubber passive samplers was undertaken though exposure in the River Alna (Norway) for an exposure time of 21 d to estimate freely dissolved concentration. Some fragrances and UV filters were predominant over other emerging and regulated contaminants, at levels up to 1600 ng L(-1) for galaxolide and 448 ng L(-1) for octocrylene. Environ Toxicol Chem 2016;35:2162-2172. © 2016 SETAC. © 2016 SETAC.

Task 90-17: Decontaminability study on the U. S. Army Resuscitation Device, Individual, Chemical (RDIC). Final report, 1 Oct 90-24 Jan 91

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

Dill, G.S.; Leonard, R.D.

1991-04-01

A study was performed to determine the effect of three commonly used field decontaminants, DS2, super tropical bleach (STB), and the M270 Decontaminating Kit, Individual (DKIE), on the Resuscitation Device, Chemical, Individual (RDIC). The RDIC system was analyzed to determine which components were accessible to chemical agents and could be degraded by them. The chemical agent susceptibility of the silicone rubber components is the weakest point in the RDIC system. The lack of accessibility of key components to the wetted DKIE wipes and the deterioration of key components by DS2 eliminates these two methods as possible decontaminant methods. STB hadmore » no noticeable effects on the RDIC and is recommended as the best field decontamination method.« less

40 CFR 720.30 - Chemicals not subject to notification requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... modifier, pH neutralizer, sequesterant, coagulant, flocculant, fire retardant, lubricant, chelating agent... plastic or rubber molding compounds, inks, drying oils, metal finishing compounds, adhesives, or paints...

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.

Characterization and Application of Passive Samplers for Monitoring of Pesticides in Water.

PubMed

Ahrens, Lutz; Daneshvar, Atlasi; Lau, Anna E; Kreuger, Jenny

2016-08-03

Five different water passive samplers were calibrated under laboratory conditions for measurement of 124 legacy and current used pesticides. This study provides a protocol for the passive sampler preparation, calibration, extraction method and instrumental analysis. Sampling rates (RS) and passive sampler-water partition coefficients (KPW) were calculated for silicone rubber, polar organic chemical integrative sampler POCIS-A, POCIS-B, SDB-RPS and C18 disk. The uptake of the selected compounds depended on their physicochemical properties, i.e., silicone rubber showed a better uptake for more hydrophobic compounds (log octanol-water partition coefficient (KOW) > 5.3), whereas POCIS-A, POCIS-B and SDB-RPS disk were more suitable for hydrophilic compounds (log KOW < 0.70).

Analysis of surface tris (2,3-dibromopropyl) phosphate on chlorobutyl rubber SCAPE suits. [flame retardant coatings

NASA Technical Reports Server (NTRS)

Schehl, T. A.; Bennett, H. D.; Bryan, C. J.; Bright, C. W.

1978-01-01

Tris (2,30-dibromopropyl) phosphate was used to confer flame retardant properties on butyl rubber formulations used in protective clothing such as the self-contained atmospheric protective ensembles (SCAPE suits) worn at Kennedy Space Center in support of Apollo, Skylab, and Apollo-Soyuz missions since 1966. Because tris (2,3-dibromopropyl) phosphate is mutagenic, surface concentrations of the compound in SCAPE suits were investigated as were as potential methods of removing or isolating it. Analytical procedures for determining surface concentrations of the tris compound on non-porous materials are described. Soap-and-water washing is the most efficient method of removing the compound from fabricated SCAPE suits and unused material.

Exposure to aged crumb rubber reduces survival time during a stress test in earthworms (Eisenia fetida).

PubMed

Pochron, Sharon; Nikakis, Jacqueline; Illuzzi, Kyra; Baatz, Andrea; Demirciyan, Loriana; Dhillon, Amritjot; Gaylor, Thomas; Manganaro, Alexa; Maritato, Nicholas; Moawad, Michael; Singh, Rajwinder; Tucker, Clara; Vaughan, Daniel

2018-04-01

Solid waste management struggles with the sustainable disposal of used tires. One solution involves shredding used tires into crumb rubber and using the material as infill for artificial turf. However, crumb rubber contains hydrocarbons, organic compounds, and heavy metals, and it travels into the environment. Earthworms living in soil contaminated with virgin crumb rubber gained 14% less body weight than did earthworms living in uncontaminated soil, but the impact of aged crumb rubber on the earthworms is unknown. Since many athletic fields contain aged crumb rubber, we compared the body weight, survivorship, and longevity in heat and light stress for earthworms living in clean topsoil to those living in topsoil contaminated with aged crumb rubber. We also characterized levels of metals, nutrients, and micronutrients of both soil treatments and compared those to published values for soil contaminated with virgin crumb rubber. Consistent with earlier research, we found that contaminated soil did not inhibit microbial respiration rates. Aged crumb rubber, like new crumb rubber, had high levels of zinc. However, while exposure to aged crumb rubber did not reduce earthworm body weight as did exposure to new crumb rubber, exposure to aged crumb rubber reduced earthworm survival time during a stress test by a statistically significant 38 min (16.2%) relative to the survival time for worms that had lived in clean soil. Aged crumb rubber and new crumb rubber appear to pose similar toxic risks to earthworms. This study suggests an environmental cost associated with the current tire-recycling solution.

40 CFR 720.30 - Chemicals not subject to notification requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... plastic or rubber molding compounds, inks, drying oils, metal finishing compounds, adhesives, or paints... solely to impart a specific physiochemical characteristic, functions as intended. (8) Any nonisolated...

Morphology, mechanical, cross-linking, thermal, and tribological properties of nitrile and hydrogenated nitrile rubber/multi-walled carbon nanotubes composites prepared by melt compounding: The effect of acrylonitrile content and hydrogenation

NASA Astrophysics Data System (ADS)

Likozar, Blaž; Major, Zoltan

2010-11-01

The purpose of this work was to prepare nanocomposites by mixing multi-walled carbon nanotubes (MWCNT) with nitrile and hydrogenated nitrile elastomers (NBR and HNBR). Utilization of transmission electronic microscopy (TEM), scanning electron microscopy (SEM), and small- and wide-angle X-ray scattering techniques (SAXS and WAXS) for advanced morphology observation of conducting filler-reinforced nitrile and hydrogenated nitrile rubber composites is reported. Principal results were increases in hardness (maximally 97 Shore, type A), elastic modulus (maximally 981 MPa), tensile strength (maximally 27.7 MPa), elongation at break (maximally 216%), cross-link density (maximally 7.94 × 1028 m-3), density (maximally 1.16 g cm-3), and tear strength (11.2 kN m-1), which were clearly visible at particular acrylonitrile contents both for unhydrogenated and hydrogenated polymers due to enhanced distribution of carbon nanotubes (CNT) and their aggregated particles in the applied rubber matrix. Conclusion was that multi-walled carbon nanotubes improved the performance of nitrile and hydrogenated nitrile rubber nanocomposites prepared by melt compounding.

Impact of extractables from rubber closures on protein stability under heat stress.

PubMed

Richter, Carolin; Lipperheide, Cornelia; Lipke, Uwe; Lamprecht, Alf

2018-06-09

Commercially available, uncoated elastomeric closures were examined in regard to a potential contribution of extracted compounds from the rubber stoppers to protein aggregation under worst-case conditions. All rubber stoppers were confirmed to comply with Ph. Eur. quality requirements. Extraction with 2-propanol under reflux-conditions for 3 h led to closure-specific extraction profiles of the tested samples. One type of rubber stopper exhibited a considerably greater number and higher content of extractables. Four extracted compounds were identified as trialkyl benzene-1, 2, 4-tricarboxylates (trivial name: trimellitates), a substance class which is increasingly established as an alternative to phthalates. A highly concentrated aqueous solution of total extractables from this rubber stopper facilitated the formation of soluble and non-soluble high-molecular aggregates when incubated with model biopharmaceuticals (recombinant human immunoglobulin G (IgG) and recombinant erythropoietin (EPO)) under stress conditions (IgG: 60-64°C for 130 min, EPO: 55°C for 8 days). Furthermore, it was shown that the surfactant concentration (polysorbate 20, 0.1 m/v % vs. 1.0 m/v %) decisively influenced the formation of high-molecular aggregates. In case of EPO, the 10 fold increased concentration of surfactant was sufficient to prevent the aggregate formation completely. This study suggests the necessity of revisiting the current test system of Ph. Eur. monograph 3.2.9 for appropriate rubber stopper quality evaluation. Copyright © 2018. Published by Elsevier B.V.

Environmental labeling of car tires--toxicity to Daphnia magna can be used as a screening method.

PubMed

Wik, Anna; Dave, Göran

2005-02-01

Car tires contain several water-soluble compounds that can leach into water and have toxic effects on aquatic organisms. Due to tire wear, 10,000 tonnes of rubber particles end up along the Swedish roads every year. This leads to a diffuse input of emissions of several compounds. Emissions of polyaromatic hydrocarbons (PAHs) are of particular concern. PAHs are ingredients of the high aromatic oil (HA oil) that is used in the rubber as a softener and as a filler. The exclusion of HA oils from car tires has started, and an environmental labeling of tires could make HA oils obsolete. The toxicity to Daphnia magna from 12 randomly selected car tires was tested in this study. Rubber from the tread of the tires was grated into small pieces, to simulate material from tire wear, and the rubber was equilibrated with dilution water for 72 h before addition of test organisms. The 24-h EC50s of the rubber pieces ranged from 0.29 to 32 gl-1, and the 48-h EC50s ranged from 0.0625 to 2.41 gl-1. Summer tires were more toxic than winter tires. After the 48-h exposure, the daphnids were exposed to UV-light for 2 h, to determine if the tires contained compounds that were phototoxic. After UV-activation the EC50s ranged from 0.0625 to 0.38 gl-1. Four of the 12 tires had a very distinct photoactivation, with a toxicity increase of >10 times. This study has shown that the used method for toxicity testing with Daphnia magna according to ISO 6341 could be used as a basis for environmental labeling of car tires.

Isolation and identification of some unknown substances in disposable nitrile-butadiene rubber gloves used for food handling.

PubMed

Mutsuga, M; Wakui, C; Kawamura, Y; Maitani, T

2002-11-01

In Japan, disposable gloves made from nitrile-butadiene rubber (NBR) are frequently used in contact with foods. In a previous paper, we investigated substances migrating from various gloves made of polyvinyl chloride, polyethylene, natural rubber and NBR. Zinc di-n-butyldithiocarbamate (ZDBC), diethyldithiocarbamate (ZDEC) used as vulcanization accelerators, di(2-ethylhexyl)phthalate (DEHP) used as a plasticizer and many unknown compounds that migrated from NBR gloves into n-heptane were detected by GC/MS. In this paper, six unknown compounds were obtained from one kind of NBR glove by n-hexane extraction and each was isolated by silica gel chromatography. From the results of NMR and mass spectral analysis of the six unknown compounds, their structures are proposed as 1,4-dione-2,5-bis(1,1-dimethylpropyl)cyclohexadiene (1), 2-(1,1-dimethylethyl)-4-(1,1,3,3-tetra methylbutyl)phenol (2), 2,6-bis(1,1-dimethylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (3), 2,4-bis(1,1,3,3-tetramethylbutyl)phenol (4), 2-(1,1-dimethylethyl)4,6-bis(1,1,3,3-tetramethylbutyl)phenol (5) and 2,4,6-tris(1,1,3,3-tetramethylbutyl)phenol (6). Compound 1 was observed in five of the seven kinds of NBR gloves, and compounds 2-4 and 6, which are not listed in Chemical Abstract (CA), were present in four kinds of gloves.

Adjustable high emittance gap filler. [reentry shielding for space shuttle vehicles

NASA Technical Reports Server (NTRS)

Leiser, D. B.; Stewart, D. A.; Smith, M.; Estrella, C. A.; Goldstein, H. E. (Inventor)

1981-01-01

A flexible, adjustable refractory filler is disclosed for filling gaps between ceramic tiles forming the heat shield of a space shuttle vehicle, to protect its aluminum skin during atmospheric reentry. The easily installed and replaced filler consists essentially of a strip of ceramic cloth coated, at least along both its longitudinal edges with a room temperature vulcanizable silicone rubber compound with a high emittance colored pigment. The filler may have one or more layers as the gap width requires. Preferred materials are basket weave aluminoborosilicate cloth, and a rubber compounded with silicon tetraboride as the emittance agent and finely divided borosilicate glass containing about 7.5% B2O3 as high temperature binder. The filler cloth strip or tape is cut to proper width and length, inserted into the gap, and fastened with previously applied drops of silicone rubber adhesive.

Circuit racing, track texture, temperature and rubber friction

NASA Astrophysics Data System (ADS)

Sharp, R. S.; Gruber, P.; Fina, E.

2016-04-01

Some general observations relating to tyre shear forces and road surfaces are followed by more specific considerations from circuit racing. The discussion then focuses on the mechanics of rubber friction. The classical experiments of Grosch are outlined and the interpretations that can be put on them are discussed. The interpretations involve rubber viscoelasticity, so that the vibration properties of rubber need to be considered. Adhesion and deformation mechanisms for energy dissipation at the interface between rubber and road and in the rubber itself are highlighted. The enquiry is concentrated on energy loss by deformation or hysteresis subsequently. Persson's deformation theory is outlined and the material properties necessary to apply the theory to Grosch's experiments are discussed. Predictions of the friction coefficient relating to one particular rubber compound and a rough surface are made using the theory and these are compared with the appropriate results from Grosch. Predictions from Persson's theory of the influence of nominal contact pressure on the friction coefficient are also examined. The extent of the agreement between theory and experiment is discussed. It is concluded that there is value in the theory but that it is far from complete. There is considerable scope for further research on the mechanics of rubber friction.

Effects of alkanolamide addition on crosslink density, mechanical and morphological properties of chloroprene rubber compounds

NASA Astrophysics Data System (ADS)

Surya, I.; Hayeemasae, N.

2018-03-01

The effects of alkanolamide (ALK) addition on crosslink density, mechanical and morphological properties of unfilled polychloroprene rubber (CR) compounds were investigated. The ALK was prepared from Refined Bleached Deodorized Palm Stearin (RBDPS) and diethanolamine and -together with magnesium and zinc oxides-incorporated into the unfilled CR compounds. The ALK loadings were 0.5, 1.0, 1.5 and 2.0 phr. It was found that ALK enhanced crosslink density, tensile modulus, tensile strength and hardness especially up to a 1.5 phr loading. Scanning Electron Microscopy (SEM) proved that the 1.5 phr of ALK exhibited the greatest matrix tearing line and surface roughness, due to the highest degree of crosslink density and mechanical properties.

Effect of organo-clay on the dielectric relaxation response of silicone rubber

NASA Astrophysics Data System (ADS)

Gharavi, N.; Razzaghi-Kashani, M.; Golshan-Ebrahimi, N.

2010-02-01

Dielectric elastomers are light weight, low-cost, highly deformable and fast response smart materials capable of converting electrical energy into mechanical work or vice versa. Silicone rubber is a well-known dielectric elastomer which is used as actuator, and in order to enhance the efficiency of this smart material, compounding of silicone rubber with various fillers can be carried out. The effect of organically modified montmorillonite (OMMT) nano-clay on improvement of dielectric properties, actuation stress and its relaxation response was considered in this study. OMMT was dispersed in room temperature vulcanized (RTV) silicone rubber, and a composite film was cast. Using an in-house actuation set-up, it was shown that the actuation stress for a given electric field intensity is higher for composites than that for pristine silicone rubber. Also, the time-dependent actuation response of the samples was evaluated, and it was shown that the characteristic relaxation time of the actuation stress for composites is less than for the pristine rubber as a result of OMMT addition.

Rubber (Hevea brasiliensis) seed oil toxicity effect and Linamarin compound analysis.

PubMed

Salimon, Jumat; Abdullah, Bashar Mudhaffar; Salih, Nadia

2012-06-13

The lipid fraction of rubber (Hevea brasiliensis (kunth. Muell)) seed was extracted and analyzed for toxicological effect. The toxicological compound such as linamarin in rubber seed oil (RSO) extracted using different solvents, such as hexane (RSOh), mixture of chloroform + methanol (RSOchl+mth) and ethanol (RSOeth) were also studied. Various methods analysis such as Fourier transforms infrared spectroscopy (FTIR) and colorimetric methods were carried out to determine the present of such compounds. FTIR spectrum of RSO did not show any presence of cyanide peak. The determination of cyanide by using colorimetric method was demonstrated no response of the cyanide in RSO and didn't show any colored comparing with commercial cyanide which observed blue color. The results showed that no functional groups such as cyanide (C ≡ N) associated with linamarin were observed. Toxicological test using rats was also conducted to further confirm the absence of such compounds. RSO did not show any toxic potential to the rats. Bioassay experiments using shrimps had been used as test organisms to evaluate the toxicity of linamarin extract from RSO(h,) RSO(chl+mth) and RSO(eth) and LC50 were found to be (211.70 %, 139.40 %, and 117.41 %, respectively). This can be attributed no hazardous linamarin were found in RSO.

Rubber (Hevea brasiliensis) seed oil toxicity effect and Linamarin compound analysis

PubMed Central

2012-01-01

Background The lipid fraction of rubber (Hevea brasiliensis (kunth. Muell)) seed was extracted and analyzed for toxicological effect. The toxicological compound such as linamarin in rubber seed oil (RSO) extracted using different solvents, such as hexane (RSOh), mixture of chloroform + methanol (RSOchl+mth) and ethanol (RSOeth) were also studied. Various methods analysis such as Fourier transforms infrared spectroscopy (FTIR) and colorimetric methods were carried out to determine the present of such compounds. Results FTIR spectrum of RSO did not show any presence of cyanide peak. The determination of cyanide by using colorimetric method was demonstrated no response of the cyanide in RSO and didn’t show any colored comparing with commercial cyanide which observed blue color. The results showed that no functional groups such as cyanide (C ≡ N) associated with linamarin were observed. Toxicological test using rats was also conducted to further confirm the absence of such compounds. RSO did not show any toxic potential to the rats. Bioassay experiments using shrimps had been used as test organisms to evaluate the toxicity of linamarin extract from RSOh, RSOchl+mth and RSOeth and LC50 were found to be (211.70 %, 139.40 %, and 117.41 %, respectively). Conclusions This can be attributed no hazardous linamarin were found in RSO. PMID:22694753

Compatibility of elastomers in alternate jet fuels

NASA Technical Reports Server (NTRS)

Kalfayan, S. H.; Fedors, R. F.; Reilly, W. W.

1979-01-01

The compatibility of elastomeric compositions of known resistance to aircraft fuels was tested for potential use in Jet A type fuels obtainable from alternate sources, such as coal. Since such fuels were not available at the time, synthetic alternate fuels were prepared by adding tetralin to a petroleum based Jet A type fuel to simulate coal derived fuels which are expected to contain higher amounts of aromatic and hydroaromatic hydrocarbons. The elastomeric compounds tested were based on butadiene-acrylonitrile rubber, a castable Thiokol polysulfide rubber, and a castable fluorosilicone rubber. Batches of various cross-link densities of these rubbers were made and their chemical stress relaxation behavior in fuel, air, and nitrogen, their swelling properties, and response to mechanical testing were determined.

The influence of nano silica particles on gamma-irradiation ageing of elastomers based on chlorosulphonated polyethylene and acrylonitrile butadiene rubber

NASA Astrophysics Data System (ADS)

Marković, G.; Marinović-Cincović, M.; Tanasić, Lj.; Jovanović, V.; Samaržija-Jovanović, S.; Vukić, N.; Budinski-Simendić, J.

2011-12-01

The goal of this work was to study gamma irradiation ageing of rubber blends based on acrylonitrile butadiene rubber (NBR) and chlorosulphonated polyethylene rubber (CSM) reinforced by silica nano particles. The NBR/CSM compounds (50: 50, w/w) filled with different content of filler (0-100 phr) were crosslinked by sulfur. The vulcanization characteristics were assessed using the rheometer with an oscillating disk. The vulcanizates were prepared in a hydraulic press. The obtained materials were exposed to the different irradiation doses (100, 200, 300 and 400 kGy). The mechanical properties (hardness, modulus at 100% elongation, tensile strength and elongation at break) and swelling numbers were assessed before and after gamma irradiation ageing.

Infrared Spectroscopic Study on Structural Change and Interfacial Interaction in Rubber Composites Filled with Silica-Kaolin Hybrid Fillers

NASA Astrophysics Data System (ADS)

Chen, Y.; Guan, J.; Hu, H.; Gao, H.; Zhang, L.

2016-07-01

A series of natural rubber/styrene butadiene rubber/polybutadiene rubber composites was prepared with nanometer silica and micron kaolin by a dry modification process, mechanical compounding, and mold vulcanization. Fourier transform infrared spectroscopy and a scanning electron microscope were used to investigate the structural changes and interfacial interactions in composites. The results showed that the "seesaw" structure was formed particularly with the incorporation of silica particles in the preparation process, which would be beneficial to the dispersibility of fillers in the rubber matrix. The kaolinite platelets were generally arranged in directional alignment. Kaolinite with smaller particle size and low-defect structure was more stable in preparation, but kaolinite with larger particle size and high defect structure tended to change the crystal structure. The composite prepared in this research exhibited excellent mechanical and thermal properties.

Application of Lignin as Antioxidant in Styrene Butadiene Rubber Composite

NASA Astrophysics Data System (ADS)

Liu, Shusheng; Cheng, Xiansu

2010-11-01

Lignin isolated from enzymatic hydrolyzed cornstalks (EHL) is a renewable natural polymer, and rubber is one of the most important polymer materials. The application of EHL in rubber industry is of great significance. The influence of EHL and antioxidant RD on the vulcanizing characteristics, thermal oxidative aging stability under free condition, and water extraction resistance of styrene-butadiene rubber (SBR) were investigated. The effect of EHL/antioxidant D composite antioxidant on the thermal oxidative ageing of SBR was also evaluated. Results showed that the protection of SBR from thermal oxidative aging by EHL/antioxidant D composite antioxidant was superior to that of antioxidant D. This is because EHL molecules have hindered phenol group and have excellent auxiliary antioxidant role with antioxidant D. Moreover, the influence of EHL on the vulcanizing characteristics of SBR compounds was better than that of antioxidant RD, and EHL can reduce the cure rate and increase the optimum cure time. It is because that the EHL molecules have hindered phenol group and methoxy group, which can form a special structure to capture free radical and terminate the chain reaction. The retained tensile strength of SBR compounds with EHL was similar to that of the samples with antioxidant RD, while the retained elongation at break of SBR compounds with EHL was higher than that of the samples with antioxidant RD. In addition, the SBR compounds with EHL have a good water extraction resistance property, which was similar to the samples with antioxidant RD. This is because EHL have large molecular weight, good stability and low solubility in water. In conclusion, due to the low price, abundant resources, non-toxic and pollution-free, etc., EHL will have broad application prospect.

Determination of thermophysical characteristics of vulcanizable rubber products by the mathematical modeling method

NASA Astrophysics Data System (ADS)

Tikhomirov, S. G.; Pyatakov, Y. V.; Karmanova, O. V.; Maslov, A. A.

2018-03-01

The studies of the vulcanization kinetics of elastomers were carried out using a Truck tyre tread rubber compound. The formal kinetic scheme of vulcanization of rubbers sulfur-accelerator curing system was used which generalizes the set of reactions occurring in the curing process. A mathematical model is developed for determining the thermal parameters vulcanizable mixture comprising algorithms for solving direct and inverse problems for system of equations of heat conduction and kinetics of the curing process. The performance of the model is confirmed by the results of numerical experiments on model examples.

Pyrolytic conversion of plastic and rubber waste to hydrocarbons with basic salt catalysts

DOEpatents

Wingfield, Jr., Robert C.; Braslaw, Jacob; Gealer, Roy L.

1985-01-01

The invention relates to a process for improving the pyrolytic conversion of waste selected from rubber and plastic to low molecular weight olefinic materials by employing basis salt catalysts in the waste mixture. The salts comprise alkali or alkaline earth compounds, particularly sodium carbonate, in an amount of greater than about 1 weight percent based on the waste feed.

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

Zhang, Miao; Du, Yonghui; Gao, Lili

A recent experimental study reported the successful synthesis of an orthorhombic FeB{sub 4} with a high hardness of 62(5) GPa [H. Gou et al., Phys. Rev. Lett. 111, 157002 (2013)], which has reignited extensive interests on whether transition-metal borides compounds will become superhard materials. However, it is contradicted with some theoretical studies suggesting transition-metal boron compounds are unlikely to become superhard materials. Here, we examined structural and electronic properties of FeB{sub 4} using density functional theory. The electronic calculations show the good metallicity and covalent Fe–B bonding. Meanwhile, we extensively investigated stress-strain relations of FeB{sub 4} under various tensile andmore » shear loading directions. The calculated weakest tensile and shear stresses are 40 GPa and 25 GPa, respectively. Further simulations (e.g., electron localization function and bond length along the weakest loading direction) on FeB{sub 4} show the weak Fe–B bonding is responsible for this low hardness. Moreover, these results are consistent with the value of Vickers hardness (11.7–32.3 GPa) by employing different empirical hardness models and below the superhardness threshold of 40 GPa. Our current results suggest FeB{sub 4} is a hard material and unlikely to become superhard (>40 GPa)« less

Fabrication of Wood-Rubber Composites Using Rubber Compound as a Bonding Agent Instead of Adhesives

PubMed Central

Shao, Dongwei; Xu, Min; Cai, Liping; Shi, Sheldon Q.

2016-01-01

Differing from the hot-pressing method in the manufacturing of traditional wood-rubber composites (WRCs), this study was aimed at fabricating WRCs using rubber processing to improve water resistance and mechanical properties. Three steps were used to make WRCs, namely, fiber-rubber mixing, tabletting, and the vulcanization molding process. Ninety-six WRC panels were made with wood fiber contents of 0%–50% at rotor rotational speeds of 15–45 rpm and filled coefficients of 0.55–0.75. Four regression equations, i.e., the tensile strength (Ts), elongation at break (Eb), hardness (Ha) and rebound resilience (Rr) as functions of fiber contents, rotational speed and filled coefficient, were derived and a nonlinear programming model were developed to obtain the optimum composite properties. Although the Ts, Eb and Rr of the panels were reduced, Ha was considerably increased by 17%–58% because of the wood fiber addition. Scanning electron microscope images indicated that fibers were well embedded in rubber matrix. The 24 h water absorption was only 1%–3%, which was much lower than commercial wood-based composites. PMID:28773591

Synthetic turf field investigation in Connecticut.

PubMed

Simcox, Nancy J; Bracker, Anne; Ginsberg, Gary; Toal, Brian; Golembiewski, Brian; Kurland, Tara; Hedman, Curtis

2011-01-01

The primary purpose of this study was to characterize the concentrations of volatile organic compounds (VOC), semivolatile organic compounds (SVOC), rubber-related chemicals such as benzothiazole (BZT) and nitrosamine, and particulate matter (PM(10)) in air at synthetic turf crumb rubber fields. Both new and older fields were evaluated under conditions of active use. Three types of fields were targeted: four outdoor crumb rubber fields, one indoor facility with crumb rubber turf, and an outdoor natural grass field. Background samples were collected at each field on grass. Personal air sampling was conducted for VOC, BZT, nitrosamines, and other chemicals. Stationary air samples were collected at different heights to assess the vertical profile of release. Air monitoring for PM(10) was conducted at one height. Bulk samples of turf grass and crumb rubber were analyzed, and meteorological data were recorded. Results showed that personal concentrations were higher than stationary concentrations and were higher on turf than in background samples for certain VOC. In some cases, personal VOC concentrations from natural grass fields were as high as those on turf. Naphthalene, BZT, and butylated hydroxytoluene (BHT) were detected in greater concentration at the indoor field compared to the outdoor fields. Nitrosamine air levels were below reporting levels. PM(10) air concentrations were not different between on-field and upwind locations. All bulk lead (Pb) samples were below the public health target of 400 ppm. More research is needed to better understand air quality at indoor facilities. These field investigation data were incorporated into a separate human health risk assessment.

Development of a Hybrid Piezo Natural Rubber Piezoelectricity and Piezoresistivity Sensor with Magnetic Clusters Made by Electric and Magnetic Field Assistance and Filling with Magnetic Compound Fluid

PubMed Central

Shimada, Kunio; Saga, Norihiko

2017-01-01

Piezoelements used in robotics require large elasticity and extensibility to be installed in an artificial robot skin. However, the piezoelements used until recently are vulnerable to large forces because of the thin solid materials employed. To resolve this issue, we utilized a natural rubber and applied our proposed new method of aiding with magnetic and electric fields as well as filling with magnetic compound fluid (MCF) and doping. We have verified the piezoproperties of the resulting MCF rubber. The effect of the created magnetic clusters is featured in a new two types of multilayered structures of the piezoelement. By measuring the piezoelectricity response to pressure, the synergetic effects of the magnetic clusters, the doping and the electric polymerization on the piezoelectric effect were clarified. In addition, by examining the relation between the piezoelectricity and the piezoresistivity created in the MCF piezo element, we propose a hybrid piezoelement. PMID:28208625

Evaluation of susceptibility of polymer and rubber materials intended into contact with drinking water on biofilm formation

PubMed

Szczotko, Maciej; Stankiewicz, Agnieszka; Jamsheer-Bratkowska, Małgorzata

Plumbing materials in water distribution networks and indoor installations are constantly evolving. The application of new, more economical solutions with plastic materials eliminates the corrosion problems, however, do not fully protect the consumer against secondary microbial contamination of water intended for human consumption caused by the presence of a biofilm on the inner surface of materials applied. National Institute of Public Health - National Institute of Hygiene conducts research aimed at a comprehensive assessment of this type of materials, resulting their further marketing authorization in Poland. Evaluation and comparison of polymer and rubber materials intended to contact with water for the susceptibility to biofilm formation. Plastic materials (polyethylene, polypropylene, polyvinyl chloride) and rubber compounds (EPDM, NBR), from different manufacturers were evaluated. The study was carried out on 37 samples, which were divided into groups according to the material of which they were made. The testing was conducted according to the method based on conditions of dynamic flow of tap water. The level of bioluminescence in swabs taken from the surface of the tested materials was investigated with a luminometer. Evaluation of plastic materials does not show major objections in terms of hygienic assessment. All materials met the evaluation criteria established for methodology used. In case of rubber compounds, a substantial part clearly exceeded the limit values, which resulted in their negative assessment and elimination of these materials from domestic market. High susceptibility to the formation of biofilm in the group of products made of rubber compounds has been demonstrated. Examined plastic materials, except for several cases, do not revealed susceptibility to biofilm formation, but application of plastics for distribution of water intended for human consumption does not fully protect water from secondary, microbiological contamination. Complete verification of plumbing materials including biofilm formation test before their introduction into the domestic market should be continued.

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.

Thin Film Composite Materials, Phase 2

DTIC Science & Technology

1987-01-01

were Kevlar coated with silicone, EPDM , or neoprene rubber , with the following results: 1. Tensile testing of coated Kevlar fabric is very difficult...Monte, CA, but the samples were not large enough for our testing program. e. EPDM . This is a rubber compound which consists of ;n ethylene propylene...materials. 2. A method was developed for measuring water vapor permeability. Neoprene and EPDM are promising as coatings with good water resistance; however

Effect of electric field induced alignment and dispersion of functionalized carbon nanotubes on properties of natural rubber

NASA Astrophysics Data System (ADS)

Gao, Jiangshan; He, Yan; Gong, Xiubin

2018-06-01

The original equipment and method for orienting multi-walled carbon nanotubes (MWCNTs) in natural rubber (NR) by alternating current (AC) electric field were reported in the present study. MWCNTs with various volume fractions were dispersed in the mixture latex which composed of natural rubber, additives and methylbenzene. The application of AC electric field during nanocomposites curing process was used to induce the formation of aligned conductive nanotube networks between the electrodes. The aligned MWCNTs in the composites have a better orientation performance and dispersion quality than these of random MWCNTs by analyzing TEM and SEM images. The effects of MWCNTs anisotropy on thermal conductivity, dielectric properties, and dynamic mechanical properties of NR were studied. The mean value of thermal conductivity of composites loading with aligned MWCNTs was 8.67% higher than that of composites with random MWCNTs due to the anisotropy of aligned MWCNTs. The compounds with aligned MWCNTs possessed low dielectric constant, loss tangents and conductivity, namely a good insulativity. The compounds loading with aligned MWCNTs had lower loss modulus and better dynamic mechanical properties than those with random MWCNTs. This method can make full use of the high thermal conductivity of MWCNTs axis, and expand the application areas of natural rubber like conducting heat in a certain direction with a high efficiency.

Organic filler from golden apple snails shells to improve the silicone rubber insulator properties

NASA Astrophysics Data System (ADS)

Tepsila, Sujirat; Suksri, Amnart

2018-02-01

This paper investigates the effect of an addition of filler compound using golden apple snail shell as an organic filler to the silicone rubber insulator. The filler obtained from golden apple snail shell is found mostly contained calcium carbonate. The organic calcium carbonate (CaCO3) with particle size of 45, 75, 100 and 300 micron were prepared. Sample of silicone rubber that were filled with fillers were tested under ASTM D638-02a type standard for mechanical test. Also, electrical test such as I-V characteristics (ASTM D257-07) and dry arc test according to ASTM D495-14 have been performed. The results revealed that using larger particle size of organic filler obtained from the golden apple snail shell resulted to higher value of dielectric constant as well as higher dielectric strength. Also, the filler helps slow down the tracking activity at an insulator surface due to its crystals of calcium carbonate. However, when using excessive amount of filler, the sample will have a drawbacks in mechanical properties. By using agriculture waste as a filler compound, one can reduced the usage of commercial CaCO3 as an inorganic materials and to lower the investment cost to a final silicone rubber product.

Presence of Polycyclic Aromatic Hydrocarbons in Rubber Packaging Materials and in Parenteral Formulations Stored in Bottles With Rubber Stoppers.

PubMed

Bohrer, Denise; Viana, Carine; Barichello, Marcia M; de Moura, Juliane F; de Carvalho, Leandro M; Nascimento, Paulo C

2017-08-01

Rubber closures are the primary packaging material for sterile preparations intended for repeated use. Important features of rubber closures are achieved after additives are added to the elastomeric material that compounds the rubber. Among these additives is carbon black. Because of its origin, carbon black may contain polycyclic aromatic hydrocarbons (PAHs). The U.S. Environmental Protection Agency has identified 16 priority PAHs on the basis of concerns that they cause or might cause cancer in animals and humans. Regulatory agencies impose carbon black purity specifications based on limits for total PAHs (0.5 mg/kg) and benzo[a]pyrene (5 μg/kg) or benzo[a]pyrene only (250 μg/kg). PAHs in rubber packaging used for pharmaceutical formulations and in parenteral products stored in containers with rubber stoppers were investigated. To this end, the method proposed by the National Institute for Occupational Safety and Health-based on high-performance liquid chromatography with ultraviolet and fluorescence detection-was adapted to determine the levels of PAHs in rubber stoppers (gray and red) and in lipid emulsions and amino acid solutions stored in bottles with rubber stoppers. The rubber materials were shown to contain 12 PAHs, in concentrations ranging from 0.25-3.31 µg/g. Only 1 of 18 samples (11 amino acid solutions and 7 lipid emulsions) was uncontaminated. The most prevalent contaminants were pyrene, benzo[a]pyrene, and fluoranthene. The total PAH concentrations in the samples ranged from 0.11-5.96 µg/mL. Components of parenteral nutrition may be contaminated with PAHs, and rubber stoppers represent a potential source of these contaminants.

Mechanical Properties of Graphene-Rubber Nanocomposites

NASA Astrophysics Data System (ADS)

Anhar, N. A. M.; Ramli, M. M.; Hambali, N. A. M. A.; Aziz, A. A.; Mat Isa, S. S.; Danial, N. S.; Abdullah, M. M. A. B.

2017-11-01

This research focused on development of wearable sensor device by using Prevulcanized Natural Rubber (PV) and Epoxidized Natural Rubber (ENR 50) latex incorporated with graphene oxide (GO), graphene paste, graphene powder and reduced graphene oxide (rGO) powder. The compounding formulation and calculation were based on phr (parts per hundred rubber) and all the samples were then tested for mechanical properties using Instron 5565 machine. It was found that the sonication effects on tensile strength may have better quality of tensile strength compared to non-sonicated GO. For PV incorporate GO, the optimum loading was best determined at loading 1.5 phr with or without sonication and similar result was recorded for PV/G. For ENR 50 incorporate graphene paste and rGO powder nanocomposite shows the best optimum was at 3.0 phr with 24 hours’ sonication.

Thermal and Kinetic Modelling of Elastomer Flow—Application to an Extrusion Die

NASA Astrophysics Data System (ADS)

Launay, J.; Allanic, N.; Mousseau, P.; Deterre, R.

2011-05-01

This paper reports and discusses the thermal and kinetic behaviour of elastomer flow inside an extrusion die. The reaction progress through the runner was modeled by using a particle tracking technique. The aim is to analyze viscous dissipation phenomena to control scorch arisen, improve the rubber compound curing homogeneity and reduce the heating time in the mould using the progress of the induction time. The heat and momentum equations were solved in three dimensions with Ansys Polyflow. A particle tracking technique was set up to calculate the reaction progress. Several simulations were performed to highlight the influence of process parameters and geometry modifications on the rubber compound thermal and cure homogeneity.

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

PubMed Central

Shimada, Kunio

2017-01-01

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

Research on the conductivity of a haptic sensor, especially with the sensor under extended condition

NASA Astrophysics Data System (ADS)

Zheng, Yaoyang; Shimada, Kunio

2008-11-01

The present paper describes the application of magnetic compound fluid (MCF) rubber as a haptic sensor for use as a material for robot sensors, artificial skin, and so on. MCF rubber is one of several new composite materials utilizing the MCF magnetic responsive fluid developed by Shimada. By applying MCF to silicon oil rubber, we can make MCF rubber highly sensitive to temperature and electric conduction. By mixing Cu and Ni particles in the silicon oil rubber and then applying a strong magnetic field, we can produce magnetic clusters at high density. The clusters form a network, as confirmed by optical observation. The MCF rubber with small deformations can act as an effective sensor. We report herein several experiments in which changes in the MCF rubber's resistance were observed when the rubber was compressed and a deformation was generated. We then made a trial haptic sensor using the MCF conductive rubber and performed many experiments to observe changes in the electrical resistance of the sensor. The experimental results showed that the proposed sensor made with MCF conductive rubber is useful for sensing small amounts of pressure or small deformations. Sometimes, however, the sensor rubber will be extended when we apply this sensor to the finger of the robot or an elbow. In these cases, it is necessary to understand the changes in sensor's conductivity. We therefore carried out some experiments to demonstrate how, under tensile conditions, the sensor's conductivity changes to a small value easier than the sensor in free condition. The results show that the sensors became more sensitive to the same pressure under extended conditions. In the present paper, we first describe the new type of functional fluid MCF rubber and a new composite material based on this MCF fluid. We then explain the production method for MCF conductive rubber and its conductive algorithm. Finally, we report our results regarding the MCF sensitivity when the MCF rubber was pulled. These experiments show an improvement in the sensitivity of the MCF rubber in the extended state.

Study on the interaction between bovine serum albumin and 4‧-azido-2‧-deoxyfluoroarabinocytidine or analogs by spectroscopy and molecular modeling

NASA Astrophysics Data System (ADS)

Wang, Ruiyong; Wang, Xiaogai; Li, Zhigang; Xie, Yuanzhe; Yang, Lingling; Shi, Jie; Chang, Junbiao

2014-11-01

The binding of 4‧-azido-2‧-deoxyfluoroarabinocytidine (FNC) or analogs (cytidine and 5‧-cytidylate monophosphate) to bovine serum albumin (BSA) was investigated by fluorescence, UV-vis absorption spectroscopy and molecular modeling. The three compounds quenched the intrinsic fluorescence of BSA and the results revealed the presence of static quenching mechanism. The positive ΔH and positive ΔS for the systems suggested that the hydrophobic forces stabilized the interaction between the compounds and protein. Results also showed that FNC was the weakest quencher.

Chemicals used in the rubber industry. An overview.

PubMed

Fishbein, L

1983-01-01

Hundreds of chemicals illustrative of many structural and use categories are employed in the rubber industry. The present overview has centered on the structural features of a number of compounds representative of several select use categories, eg, vulcanizing agents, accelerators, antioxidants, antiozonants, and blowing agents, with focus on the nature of their impurities, their chemical degradation, and by-products, as well as on those chemicals that can be converted to N-nitrosamines.

SIMS depth profiling of rubber-tyre cord bonding layers prepared using 64Zn depleted ZnO

NASA Astrophysics Data System (ADS)

Fulton, W. S.; Sykes, D. E.; Smith, G. C.

2006-07-01

Zinc oxide and copper/zinc sulphide layers are formed during vulcanisation and moulding of rubber to brass-coated steel tyre reinforcing cords. Previous studies have described how zinc diffuses through the rubber-brass interface to form zinc sulphide, and combines with oxygen to create zinc oxide during dezincification. The zinc is usually assumed to originate in the brass of the tyre cord, however, zinc oxide is also present in the rubber formulation. We reveal how zinc from these sources is distributed within the interfacial bonding layers, before and after heat and humidity ageing. Zinc oxide produced using 64Zn-isotope depleted zinc was mixed in the rubber formulation in place of the natural ZnO and the zinc isotope ratios within the interfacial layers were followed by secondary ion mass spectroscopy (SIMS) depth profiling. Variations in the relative ratios of the zinc isotopes during depth profiling were measured for unaged, heat-aged and humidity-aged wire samples and in each case a relatively large proportion of the zinc incorporated into the interfacial layer as zinc sulphide was shown to have originated from ZnO in the rubber compound.

Fabrication of Wood-Rubber Composites Using Rubber Compound as a Bonding Agent Instead of Adhesives.

PubMed

Shao, Dongwei; Xu, Min; Cai, Liping; Shi, Sheldon Q

2016-06-14

Differing from the hot-pressing method in the manufacturing of traditional wood-rubber composites (WRCs), this study was aimed at fabricating WRCs using rubber processing to improve water resistance and mechanical properties. Three steps were used to make WRCs, namely, fiber-rubber mixing, tabletting, and the vulcanization molding process. Ninety-six WRC panels were made with wood fiber contents of 0%-50% at rotor rotational speeds of 15-45 rpm and filled coefficients of 0.55-0.75. Four regression equations, i.e. , the tensile strength ( T s), elongation at break ( E b), hardness ( H a) and rebound resilience ( R r) as functions of fiber contents, rotational speed and filled coefficient, were derived and a nonlinear programming model were developed to obtain the optimum composite properties. Although the T s, E b and R r of the panels were reduced, H a was considerably increased by 17%-58% because of the wood fiber addition. Scanning electron microscope images indicated that fibers were well embedded in rubber matrix. The 24 h water absorption was only 1%-3%, which was much lower than commercial wood-based composites.

Environmental exposure to preformed nitroso compounds.

PubMed

Tricker, A R; Spiegelhalder, B; Preussmann, R

1989-01-01

In the human environment, nitrosatable amine precursors to N-nitroso compounds and nitrosating species such as nitrite and oxides of nitrogen are abundant. As a result, the formation of N-nitroso compounds and human exposure to these compounds show a rather complex pattern. The largest known human exposures to exogenous N-nitrosamines occur in the work place. This is particularly evident in the rubber and tyre manufacturing industry and in metal cutting and grinding shops. Nearly all industries which are concerned with the production and/or use of amines have a related nitrosamine problem. Outside the industrial environment, commodities such as cosmetics, pharmaceuticals, rubber and household products, which are either prepared from amines or contain high concentrations of amino compounds, may be subject to contamination by low concentrations of N-nitroso compounds. This contamination may result from the use of contaminated starting materials, in particular amines, or from the formation of N-nitroso compounds during manufacturing processes. A similar problem exists with agricultural chemicals. As our knowledge of the occurrence and formation of N-nitroso compounds in the environment increases, preventive measures can be introduced, particularly in manufacturing industries, to reduce the levels of human exposure to nitrosamines in the work place and to protect the consumer from nitrosamine exposure from household commodities.

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.

Morphological explanation of high tear resistance of EPDM/NR rubber blends.

PubMed

Gögelein, Christoph; Beelen, Henri Jacob Hubert; van Duin, Martin

2017-06-14

The fatigue properties of cross-linked blends of ethylene propylene diene rubber (EPDM) with low natural rubber (NR) content and reinforced with carbon black (CB) are studied. It is found that such EPDM/NR compounds have superior crack growth resistance and fatigue lifetime. For low NR contents, transmission electron microscopy reveals that the NR phase forms small droplets of 20-50 nm. Remarkably, these droplets are even smaller than the primary CB particles. Atomic force microscopy shows that the the NR phase droplets have a higher loss factor and a smaller elastic modulus than the surrounding EPDM matrix. Rheometer measurements are used to study the effect of the phase morphology on the rubber mechanical properties. These rheological data are compared with the prediction of the Eshelby model describing the effect of elastic inclusions on solids. A complex interplay between the rubber phase morphology and the solubility of both the sulfur cross-linking system and CB is observed, which cannot be predicted theoretically. It is proposed that the soft NR droplets effectively inhibit the crack propagation in the EPDM matrix.

Hazardous organic chemicals in rubber recycled tire playgrounds and pavers.

PubMed

Llompart, Maria; Sanchez-Prado, Lucia; Pablo Lamas, J; Garcia-Jares, Carmen; Roca, Enrique; Dagnac, Thierry

2013-01-01

In this study, the presence of hazardous organic chemicals in surfaces containing recycled rubber tires is investigated. Direct material analyses using solvent extraction, as well as SPME analysis of the vapour phase above the sample, were carried out. Twenty-one rubber mulch samples were collected from nine different playgrounds. In addition, seven commercial samples of recycled rubber pavers were acquired in a local store of a multinational company. All samples were extracted by ultrasound energy, followed by analysis of the extract by GC-MS. The analysis confirmed the presence of a large number of hazardous substances including PAHs, phthalates, antioxidants (e.g. BHT, phenols), benzothiazole and derivatives, among other chemicals. The study evidences the high content of toxic chemicals in these recycled materials. The concentration of PAHs in the commercial pavers was extremely high, reaching values up to 1%. In addition, SPME studies of the vapour phase above the samples confirm the volatilisation of many of those organic compounds. Uses of recycled rubber tires, especially those targeting play areas and other facilities for children, should be a matter of regulatory concern. Copyright © 2012 Elsevier Ltd. All rights reserved.

Elastic MCF Rubber with Photovoltaics and Sensing for Use as Artificial or Hybrid Skin (H-Skin): 1st Report on Dry-Type Solar Cell Rubber with Piezoelectricity for Compressive Sensing.

PubMed

Shimada, Kunio

2018-06-05

Ordinary solar cells are very difficult to bend, squash by compression, or extend by tensile strength. However, if they were to possess elastic, flexible, and extensible properties, in addition to piezo-electricity and resistivity, they could be put to effective use as artificial skin installed over human-like robots or humanoids. Further, it could serve as a husk that generates electric power from solar energy and perceives any force or temperature changes. Therefore, we propose a new type of artificial skin, called hybrid skin (H-Skin), for a humanoid robot having hybrid functions. In this study, a novel elastic solar cell is developed from natural rubber that is electrolytically polymerized with a configuration of magnetic clusters of metal particles incorporated into the rubber, by applying a magnetic field. The material thus produced is named magnetic compound fluid rubber (MCF rubber) that is elastic, flexible, and extensible. The present report deals with a dry-type MCF rubber solar cell that uses photosensitized dye molecules. First, the photovoltaic mechanism in the material is investigated. Next, the changes in the photovoltaic properties of its molecules due to irradiation by visible light are measured under compression. The effect of the compression on its piezoelectric properties is investigated.

Mechanical & morphological properties of attapulgite/NR composites: Effect of mixing time variation

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

Nor, Nor Aina Mohd, E-mail: ayena90@yahoo.com; Othman, Nadras, E-mail: srnadras@usm.my; Ismail, Hanafi, E-mail: ihanafi@usm.my

2015-07-22

The development of composite material based on attapulgite clay (ATP) as a filler and natural rubber (NR) matrices were prepared by combination of melt mixing and latex compounding methods. Sonication technique was chosen in this work to disperse the attapulgite suspension. 6 phr of attapulgite loading was fabricated using different time of mixing ranging from 30 minutes until 2 hours and sonication time was kept constant at 15 minutes. Then, co-coagulating HA latex with attapulgite clay suspension through latex compounding method produced the masterbatch. The masterbatch was compounded with natural rubber by melt mixing method. The mechanical and morphological characteristicsmore » were investigated in this work. From mechanical testing, M1 showed the highest value of tensile and tear strength. By comparing with M30 and M2, M1 shows high 300% tensile modulus and lower crosslink density. However, when the time of mixing was prolonged to 2 hours, the results for tensile strength, elongation at break and tear strength were decreased. This is due to flocculation of attapulgite particles. Sonication techniques also proved that the tensile strength and elongation at break of these three samples were higher compared to gum NR (NR) and attapulgite compounded with NR using a conventional method (in-situ 6). From field emission scanning electron microscope (FESEM) results, it revealed that M1 had good dispersion in the NR system. It is proved that the higher tensile strength was due to good dispersion of attapulgite clay in the NR matrix. It was also supported from crosslink density, which is lower than NR and in-situ 6 results. It showed that the penetration of toluene solvent into rubber compound was restricted. The optimum time, M1 give the best results, which can be compared to control the sample.« less

Silicone rubber selection for passive sampling of pesticides in water.

PubMed

Martin, A; Margoum, C; Randon, J; Coquery, M

2016-11-01

Silicone rubber can extract organic compounds with a broad range of polarities (logKow>2-3) from aqueous samples. Such compounds include substances of major concern in the protection of aquatic ecosystems and human health, e.g. pesticides. Silicone rubbers (SRs) with various characteristics have been successfully used in sorptive methods for water sample extraction in the laboratory (SPME, SBSE), and for passive sampling in aquatic environments. However, only few studies have evaluated variability in organic compound sorption due to the origin of SRs, particularly for pesticides. The aim of this study was to select an SR for the extraction of pesticides from water samples by passive sampling. To this end we measured the impact of seven SR formulations on sorption capacity, defined by the partition coefficient (Ksw). Kinetic experiments and sorption isotherms were performed to determine extraction recovery as a selection criterion for SRs, and pesticide partition coefficients. Very large differences in affinity for pesticides were found between two kinds of SRs: "Polymerized SR kits" and "Manufactured SRs". One SR was chosen among the "Manufactured SRs", and the Ksw values of 21 pesticides were determined, filling a gap in the literature (1.50

Barrier Properties of Layered-Silicate Reinforced Ethylenepropylenediene Monomer/Chloroprene Rubber Nanorubbers.

PubMed

Wu, Chang Mou; Hsieh, Wen Yen; Cheng, Kuo Bin; Lai, Chiu-Chun; Lee, Kuei Chi

2018-05-09

The triacetin and nitroglycerin barrier properties of layered-silicate reinforced ethylenepropylenediene monomer/chloroprene rubber (EPDM/CR) nanorubbers were investigated as rocket-propellant inhibitors. EPDM/CR nanorubbers with intercalated structures were formulated and prepared by the melt-compounding method. The triacetin permeability and nitroglycerin absorption were observed to decrease with increasing layered-silicate content. The layered silicates also improved the flame retardancies of the nanorubbers by forming silicate reinforced carbonaceous chars. Layered-silicate reinforced EPDM/CR nanorubbers are potentially effective rocket propellant-inhibiting materials.

40 CFR 60.544 - Monitoring of operations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance for the Rubber Tire... organic compounds based on a detection principle such as infrared, photoionization, or thermal...

Summer Research Program (1992). Summer Faculty Research Program (SFRP) Reports. Volume 5B. Wright Laboratory

DTIC Science & Technology

1992-12-01

composite system was made of carbon black-filled proprietary rubber compound matrix and 1260/2 39- 6 nylon cord reinforcement laid at an angle of +/-38...1.5 urn. 2) These are ternary compounds without the additional complication of added phosphorous as in the common compound InGaAsP. 3) Recent...theoretical coirputations indicate that these compounds may have large optical nonlinearities. For thin layers the lattice mismatch induces internal strain

40 CFR 60.542a - Alternate standard for volatile organic compounds.

Code of Federal Regulations, 2010 CFR

2010-07-01

... PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance for the Rubber Tire Manufacturing Industry § 60.542a Alternate standard for volatile organic compounds. (a) On and after the date on which the initial performance test, required by § 60.8, is completed, but no...

Study on the interaction between bovine serum albumin and 4'-azido-2'-deoxyfluoroarabinocytidine or analogs by spectroscopy and molecular modeling.

PubMed

Wang, Ruiyong; Wang, Xiaogai; Li, Zhigang; Xie, Yuanzhe; Yang, Lingling; Shi, Jie; Chang, Junbiao

2014-11-11

The binding of 4'-azido-2'-deoxyfluoroarabinocytidine (FNC) or analogs (cytidine and 5'-cytidylate monophosphate) to bovine serum albumin (BSA) was investigated by fluorescence, UV-vis absorption spectroscopy and molecular modeling. The three compounds quenched the intrinsic fluorescence of BSA and the results revealed the presence of static quenching mechanism. The positive ΔH and positive ΔS for the systems suggested that the hydrophobic forces stabilized the interaction between the compounds and protein. Results also showed that FNC was the weakest quencher. Copyright © 2014 Elsevier B.V. All rights reserved.

Zinc poisoning

MedlinePlus

... including: Compounds used to make paint, rubber, dyes, wood preservatives, and ointments Rust prevention coatings Vitamin and ... a full recovery. If the poisoning is severe, death may occur up to a week after swallowing ...

Theoretical studies of the nitrogen containing compounds adsorption behavior on Na(I)Y and rare earth exchanged RE(III)Y zeolites.

PubMed

Geng, Wei; Zhang, Haitao; Zhao, Xuefei; Zan, Wenyan; Gao, Xionghou; Yao, Xiaojun

2015-01-01

In this work, the adsorption behavior of nitrogen containing compounds including NH3, pyridine, quinoline, and carbazole on Na(I)Y and rare earth exchanged La(III)Y, Pr(III)Y, Nd(III)Y zeolites was investigated by density functional theory (DFT) calculations. The calculation results demonstrate that rare earth exchanged zeolites have stronger adsorption ability for nitrogen containing compounds than Na(I)Y. Rare earth exchanged zeolites exhibit strongest interaction with quinoline while weakest with carbazole. Nd(III)Y zeolites are found to have strongest adsorption to all the studied nitrogen containing compounds. The analysis of the electronic total charge density and electron orbital overlaps show that nitrogen containing compounds interact with zeolites by π-electrons of the compounds and the exchanged metal atom. Mulliken charge population analysis also proves that adsorption energies are strongly dependent on the charge transfer between the nitrogen containing molecules and exchanged metal atom in the zeolites.

Environmental impact of highway construction and repair materials on surface and ground waters. Case study: crumb rubber asphalt concrete.

PubMed

Azizian, Mohammad F; Nelson, Peter O; Thayumanavan, Pugazhendhi; Williamson, Kenneth J

2003-01-01

The practice of incorporating certain waste products into highway construction and repair materials (CRMs) has become more popular. These practices have prompted the National Academy of Science, National Cooperative Highway Research Program (NCHRP) to research the possible impacts of these CRMs on the quality of surface and ground waters. State department of transportations (DOTs) are currently experimenting with use of ground tire rubber ( crumb rubber) in bituminous construction and as a crack sealer. Crumb rubber asphalt concrete (CR-AC) leachates contain a mixture of organic and metallic contaminants. Benzothiazole and 2(3H)-benzothiazolone (organic compounds used in tire rubber manufacturing) and the metals mercury and aluminum were leached in potentially harmful concentrations (exceeding toxic concentrations for aquatic toxicity tests). CR-AC leachate exhibited moderate to high toxicity for algae ( Selenastrum capriconutum) and moderate toxicity for water fleas ( Daphnia magna). Benzothiazole was readily removed from CR-AC leachate by the environmental processes of soil sorption, volatilization, and biodegradation. Metals, which do not volatilize or photochemically or biologically degrade, were removed from the leachate by soil sorption. Contaminants from CR-AC leachates are thus degraded or retarded in their transport through nearby soils and ground waters.

Contamination of injectable solutions with 2-mercaptobenzothiazole leached from rubber closures.

PubMed

Reepmeyer, J C; Juhl, Y H

1983-11-01

An impurity, discovered in a sample of digoxin injectable solution commercially packaged in a syringe for single-dose delivery, was found to originate from the rubber closure of the syringe and was identified as 2-mercaptobenzothiazole, a common accelerator for rubber vulcanization. Several similarly packaged injectable solutions of a variety of drugs from various manufacturers were examined and over half contained 2-mercaptobenzothiazole. The compound was identified by UV spectrophotometry (including a pH-dependent shift in its absorbance maximum), by mass spectrometry, and by comparison with standard 2-mercaptobenzothiazole using silica gel and reverse-phase high-performance liquid chromatography (HPLC). The presence of this impurity in injectable solutions may have implications with regard to toxicity and may interfere with the assay of digoxin injectable solution by HPLC.

‘Weakest Link’ as a Cognitive Vulnerability Within the Hopelessness Theory of Depression in Chinese University Students

PubMed Central

Xiao, Jing; Qiu, Yu; He, Yini; Cui, Lixia; Auerbach, Randy P.; McWhinnie, Chad M.; Yao, Shuqiao

2015-01-01

The current study tested the cognitive vulnerability–stress component of hopelessness theory using a ‘weakest link’ approach (e.g. an individual is as cognitively vulnerable to depression as his or her most depressogenic attributional style makes him or her) in a sample of Chinese university students. Participants included 520 students in Changsha. During an initial assessment, participants completed measures assessing weakest link, depressive symptoms and occurrence of negative events once a month for 6 months. Results from hierarchical linear modelling analyses showed that higher levels of weakest link scores were associated with greater increases in depressive symptoms following the occurrence of negative events. Higher weakest link level was associated with greater increases in depressive symptoms over time. These results provide support for the applicability of the ‘weakest link’ approach to the hopelessness theory to Chinese university students. PMID:24639362

'Weakest Link' as a Cognitive Vulnerability Within the Hopelessness Theory of Depression in Chinese University Students.

PubMed

Xiao, Jing; Qiu, Yu; He, Yini; Cui, Lixia; Auerbach, Randy P; McWhinnie, Chad M; Yao, Shuqiao

2016-02-01

The current study tested the cognitive vulnerability-stress component of hopelessness theory using a 'weakest link' approach (e.g. an individual is as cognitively vulnerable to depression as his or her most depressogenic attributional style makes him or her) in a sample of Chinese university students. Participants included 520 students in Changsha. During an initial assessment, participants completed measures assessing weakest link, depressive symptoms and occurrence of negative events once a month for 6 months. Results from hierarchical linear modelling analyses showed that higher levels of weakest link scores were associated with greater increases in depressive symptoms following the occurrence of negative events. Higher weakest link level was associated with greater increases in depressive symptoms over time. These results provide support for the applicability of the 'weakest link' approach to the hopelessness theory to Chinese university students. Copyright © 2014 John Wiley & Sons, Ltd.

A study of the role of fillers in silicone rubber compounds for outdoor insulation

NASA Astrophysics Data System (ADS)

Meyer, Luiz Henrique

Polymeric materials are being used as a housing material on high voltage outdoor insulation as an alternative to porcelain or glass in line insulators, surge arresters, station posts, and bushings. Among the polymeric materials in use, silicone rubber has proven to have good aging performance under polluted conditions by keeping low levels of leakage current by virtue of its hydrophobicity. However, the exposure of polymeric materials to contaminated and humid environments can lead to certain surface conditions that reduces hydrophobicity increasing leakage current levels, giving rise to dry band arcing. Dry band arcing produces heat, which can result in tracking or erosion of the housing material. Although this dry band arcing does not harm porcelain or glass housings, it will erode pure silicone rubber to such an extent that its application in outdoor environments is not, practical. Fillers are added to silicone rubber to improve tracking and erosion resistance. Among the filler choices, alumina trihydrate (ATH) and silica have been extensively adopted in the compounding of polymeric housings. ATH is a flame retardant that has a molecular water in its formulation. Whenever the surface temperature of an ATH filled polymer reaches approximately 220°C, the water of hydration is released from the ATH molecule, what is recognized as an efficient way to cool down the surface, for example, in the case of dry band arcing. Alternatively, silica has very good bonding with the polymer backbone, imparting mechanical strength to the composite matrix. In addition, fillers such as ATH or silica increase the thermal conductivity of silicone rubber composites, which facilitates moving the heat away from its source, that is, from the origin of dry band arcing. Although heat is considered to be the main degradation factor when dry band arcing occurs, very little information is available on the thermal performance of filled silicone rubber. The standard methods available to test tracking and erosion resistance of filled silicone rubber do not allow to delineate the fundamentals of the thermal degradation, where the heat from the dry band arcing is the main degradation factor. In this work, a thermal imaging camera is used to investigate the thermal performance of filled silicone rubber in an inclined plane test. Infrared laser based techniques are developed to study the material performance. Furthermore, this thesis addresses the measurement of the thermal conductivity, based on infrared laser and thermal imaging, but using simple concepts. Theoretical and empirical models are developed in support of the experimental investigation.

Glove permeation by semiconductor processing mixtures containing glycol-ether derivatives.

PubMed

Zellers, E T; Ke, H Q; Smigiel, D; Sulewski, R; Patrash, S J; Han, M W; Zhang, G Z

1992-02-01

Results of permeation tests of several glove materials challenged with semiconductor processing formulations containing glycolether derivatives are described. Commercial glove samples of nitrile rubber (Edmont), natural rubber (Edmont and Baxter), butyl rubber (North), PVC Baxter), a natural rubber/neoprene/nitrile blend (Pioneer), and a natural rubber/neoprene blend (Playtex) were tested according to the ASTM F739-85 permeation test method (open-loop configuration). The liquid formulations examined included a positive photoresist thinner containing 2-ethoxyethyl acetate (2-EEA), n-butyl acetate, and xylene; a positive photoresist containing 2-EEA, n-butyl acetate, xylene, polymer resins, and photoactive compounds; a negative photoresist containing 2-methoxyethanol (2-ME), xylene, and cyclized poly(isoprene); and pure 2-methoxyethyl acetate (2-MEA), which is the solvent used in a commercial electron-beam resist. With the exception of the negative photoresist, butyl rubber provided the highest level of protection against the solvent mixtures tested, with no breakthrough observed after 4 hr of continuous exposure at 25 degrees C. Nitrile rubber provided the highest level of protection against the negative photoresist and reasonably good protection against initial exposure to the other solvent mixtures. Gloves consisting of natural rubber or natural rubber blends provided less protection against the mixtures than either nitrile or butyl rubber. For most of the glove samples, permeation of the glycol-ether derivatives contained in the mixtures was faster than that predicted from the permeation of the pure solvents. Increasing the exposure temperature from 25 to 37 degrees C did not significantly affect the performance of the butyl rubber glove. For the other gloves, however, exposures at 37 degrees C resulted in decreases in breakthrough times of 25-75% and increases in steady-state permeation rates of 80-457% relative to values obtained at 25 degrees C. Repeated exposure of nitrile rubber samples resulted in shorter breakthrough times for all mixture components. In fact, exposure for as little as one-half of the nominal breakthrough time followed by air drying overnight resulted in measurable quantities of one or more of the component solvents at the inner surface of the gloves at the beginning of the next exposure. This effect was not observed with the butyl rubber samples. With the exception of the negative photoresist, heating previously exposed nitrile rubber samples at 70 degrees C for 20 hr prior to retesting reduced or eliminated the effects of residual solvents, permitting reuse of the gloves. The use of thin PVC or natural rubber gloves adjacent to the nitrile gloves provided moderate increases in permeation resistance.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of leachate from crumb rubber and zinc in green roofs on the survival, growth, and resistance characteristics of Salmonella enterica subsp. enterica serovar Typhimurium.

PubMed

Crampton, Mollee; Ryan, Allayna; Eckert, Cori; Baker, Katherine H; Herson, Diane S

2014-05-01

The use of green roofs is a growing practice worldwide, particularly in densely populated areas. In an attempt to find new methods for recycling crumb rubber, incorporation of crumb rubber into artificial medium for plant growth in green roofs and similar engineered environments has become an attractive option for the recycling of waste tires. Though this approach decreases waste in landfills, there are concerns about the leaching of zinc and other heavy metals, as well as nutrient and organic compounds, into the environment. The present study analyzed the impact of leachate from crumb rubber and zinc on the growth and viability of Salmonella enterica subsp. enterica serovar Typhimurium. Zinc was chosen for further studies since it has been previously implicated with other biological functions, including biofilm formation, motility, and possible cross-resistance to antimicrobial agents. The study showed that Salmonella can colonize crumb rubber and that crumb rubber extract may provide nutrients that are usable by this bacterium. Salmonella strains with reduced susceptibility (SRS) to zinc were obtained after subculturing in increasing concentrations of zinc. The SRS exhibited differences in gene expression of flux pump genes zntA and znuA compared to that of the parent when exposed to 20 mM added zinc. In biofilm formation studies, the SRS formed less biofilm but was more motile than the parental strain.

Mechanical Enhancement of Sensitivity in Natural Rubber Using Electrolytic Polymerization Aided by a Magnetic Field and MCF for Application in Haptic Sensors

PubMed Central

Shimada, Kunio; Saga, Norihiko

2016-01-01

Sensors are essential to the fulfillment of every condition of haptic technology, and they need simultaneously to sense shear stress as well as normal force, and temperature. They also must have a strong and simple structure, softness, and large extension. To achieve these conditions simultaneously, we enhanced the sensitivity of sensors utilizing natural rubber (NR)-latex through the application of electrolytic polymerization focused on the isoprene C=C bonds in natural rubbers such as NR-latex, and then applied a magnetic field and magnetic compound fluid (MCF) as magnetically responsive fluid. When an electric field alone was used in the rubber, the effect of electrolytic polymerization was very small compared to the effect in well-known conductive polymer solution such as plastic. The MCF developed by Shimada in 2001 involved magnetite and metal particles, and acts as a filler in NR-latex. By utilizing the magnetic, electric fields and the MCF, we aligned the electrolytically polymerized C=C along the magnetic field line with the magnetic clusters formed by the aggregation of magnetite and metal particles so as to enhance the effect of electrolytic polymerization. We then demonstrated the effectiveness of the new method of rubber vulcanization on the sensitivity of the rubber by experimentally investigating its electric and dynamic characteristics. PMID:27649210

The response of earthworms (Eisenia fetida) and soil microbes to the crumb rubber material used in artificial turf fields.

PubMed

Pochron, Sharon T; Fiorenza, Andrew; Sperl, Cassandra; Ledda, Brianne; Lawrence Patterson, Charles; Tucker, Clara C; Tucker, Wade; Ho, Yuwan Lisa; Panico, Nicholas

2017-04-01

Municipalities have been replacing grass fields with artificial turf, which uses crumb rubber infill made from recycled tires. Crumb rubber contains hydrocarbons, organic compounds, and heavy metals. Water runoff from crumb rubber fields contains heavy metals. These components can damage the environment. We contaminated topsoil with new crumb rubber and measured its impact on earthworms and soil microbes. Specifically, we compared soil microbe activity and earthworm health, survivorship, and longevity in heat and light stress under two soil regimes: clean topsoil and clean topsoil contaminated with crumb rubber. We then characterized levels of metals, nutrients, and micronutrients of both soil treatments and compared those to published New York soil background levels and to levels set by the New York State Department of Environmental Conservation (DEC) as remediation goals. We found that: 1) contaminated soil did not inhibit microbial respiration rates, 2) earthworm survivorship was not impacted by exposure to contaminated soil, 3) earthworms' ability to cope with heat and light stress remained unchanged after living in contaminated soil, but 4) earthworms living in contaminated soil gained 14% less body weight than did earthworms living in uncontaminated soil. We also found that, with the exception of zinc, heavy metals in our contaminated soil did not exceed the background levels found throughout New York State or the remediation targets set by the DEC. Published by Elsevier Ltd.

Mechanical Enhancement of Sensitivity in Natural Rubber Using Electrolytic Polymerization Aided by a Magnetic Field and MCF for Application in Haptic Sensors.

PubMed

Shimada, Kunio; Saga, Norihiko

2016-09-18

Sensors are essential to the fulfillment of every condition of haptic technology, and they need simultaneously to sense shear stress as well as normal force, and temperature. They also must have a strong and simple structure, softness, and large extension. To achieve these conditions simultaneously, we enhanced the sensitivity of sensors utilizing natural rubber (NR)-latex through the application of electrolytic polymerization focused on the isoprene C=C bonds in natural rubbers such as NR-latex, and then applied a magnetic field and magnetic compound fluid (MCF) as magnetically responsive fluid. When an electric field alone was used in the rubber, the effect of electrolytic polymerization was very small compared to the effect in well-known conductive polymer solution such as plastic. The MCF developed by Shimada in 2001 involved magnetite and metal particles, and acts as a filler in NR-latex. By utilizing the magnetic, electric fields and the MCF, we aligned the electrolytically polymerized C=C along the magnetic field line with the magnetic clusters formed by the aggregation of magnetite and metal particles so as to enhance the effect of electrolytic polymerization. We then demonstrated the effectiveness of the new method of rubber vulcanization on the sensitivity of the rubber by experimentally investigating its electric and dynamic characteristics.

Magnetic whiskers of p-aminobenzoic acid and their use for preparation of filled and microchannel silicone rubbers

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

Semenov, V. V., E-mail: vvsemenov@iomc.ras.ru; Loginova, V. V.; Zolotareva, N. V.

A thin cobalt layer has been formed on the surface of p-aminobenzoic acid whiskers by chemical vapor deposition (CVD). The metallized crystals have been oriented in liquid polydimethylsiloxane rubber by applying a dc magnetic field. After vulcanization, the filler has been removed by processing in an alcohol solution of trifluoroacetic acid. The cobalt deposition on the surface of the organic compound and the properties of metallized whiskers are investigated by optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM).

Barrier Properties of Layered-Silicate Reinforced Ethylenepropylenediene Monomer/Chloroprene Rubber Nanorubbers

PubMed Central

Hsieh, Wen Yen; Cheng, Kuo Bin; Lai, Chiu-Chun; Lee, Kuei Chi

2018-01-01

The triacetin and nitroglycerin barrier properties of layered-silicate reinforced ethylenepropylenediene monomer/chloroprene rubber (EPDM/CR) nanorubbers were investigated as rocket-propellant inhibitors. EPDM/CR nanorubbers with intercalated structures were formulated and prepared by the melt-compounding method. The triacetin permeability and nitroglycerin absorption were observed to decrease with increasing layered-silicate content. The layered silicates also improved the flame retardancies of the nanorubbers by forming silicate reinforced carbonaceous chars. Layered-silicate reinforced EPDM/CR nanorubbers are potentially effective rocket propellant-inhibiting materials. PMID:29747427

Effect of combination ultrasonic and ball milling techniques of commercial fillers dispersion on mechanical properties of natural rubber (NR) latex films

NASA Astrophysics Data System (ADS)

Hamran, Noramirah; Rashid, Azura A.

2017-07-01

Commercial fillers such as silica and carbon black generally impart the reinforcing effects in dry rubber compound, but have an adverse effect on Natural rubber (NR) latex compounds. The addition of commercial fillers in NR latex has reduced the mechanical properties of NR latex films due to the destabilization effect in the NR latex compounds which govern by the dispersion quality, particle size and also the pH of the dispersion itself. The ball milling process is the conventional meth od of preparation of dispersions and ultrasonic has successfully used in preparation of nano fillers such as carbon nanotube (CNT). In this study the combination between the conventional methods; ball milling together the ultrasonic method were used to prepare the silica and carbon black dispersions. The different duration of ball milling (24, 48 and 72 hours) was compared with the ultrasonic method (30, 60, 90 and 120 minutes). The combination of ball milling and ultrasonic from the optimum individual technique was used to investigate the reduction of particle size of the fillers. The particle size analyzer, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) test were carried out to investigate the obtained particle size and the tensile and tear test were carried out to investigate the mechanical properties of the NR latex films. The reduction of filler particle size is expected to impart the properties of NR latex films.

Antifungal Compound Isolated from Catharanthus roseus L. (Pink) for Biological Control of Root Rot Rubber Diseases.

PubMed

Zahari, R; Halimoon, N; Ahmad, M F; Ling, S K

2018-01-01

Rigidoporus microporus, Ganoderma philippii, and Phellinus noxius are root rot rubber diseases and these fungi should be kept under control with environmentally safe compounds from the plant sources. Thus, an antifungal compound isolated from Catharanthus roseus was screened for its effectiveness in controlling the growth of these fungi. The antifungal compound isolated from C. roseus extract was determined through thin layer chromatography (TLC) and nuclear magnetic resonance (NMR) analysis. Each C. roseus of the DCM extracts was marked as CRD1, CRD2, CRD3, CRD4, CRD5, CRD6, and CRD7, respectively. TLC results showed that all of the C. roseus extracts peaked with red colour at Rf = 0.61 at 366 nm wavelength, except for CRD7. The CRD4 extract was found to be the most effective against R. microporus and G. philippii with inhibition zones of 3.5 and 1.9 mm, respectively, compared to that of other extracts. These extracts, however, were not effective against P. noxius. The CRD4 extract contained ursolic acid that was detected by NMR analysis and the compound could be developed as a biocontrol agent for controlling R. microporus and G. philippii. Moreover, little or no research has been done to study the effectiveness of C. roseus in controlling these fungi.

Mechanisms to improve the mechanical performance of surgical gloves

NASA Astrophysics Data System (ADS)

Watkins, Michelle Hoyt

1997-11-01

The use of gloves as a barrier to cross infection in the medical industry has increased substantially due to the heightened awareness of viral transmission, especially the human immunodeficiency virus and the hepatitis B virus. The glove must allow for tactile sensation, comfort and long use times, while providing equally critical mechanical performance. The majority of surgical gloves are made of natural rubber latex which do not give a critical level of cut-resistance or puncture-resistance. Natural rubber latex gloves are also known to cause latex allergy with hypersensitivity reactions ranging from mild skin rashes to more severe bronchial asthma, anaphylactic reactions, and even death. It has been postulated natural rubber latex (NRL) proteins cause these allergic reactions. The research that has been conducted comprises two approaches that have been explored for improving the cut-resistance of surgical gloves. The first method involves an integral fiber-latex structure that possesses the combination of high reversible extensibility, barrier performance and retention of tactile sense. Improvement in mechanical properties in excess of 85% has been achieved as well as an improvement in cut-resistance. The second method involves the incorporation of a low concentration of ultra high molecular weight (UHMW) polyacrylamide. Although the initial premise for using a UHMW polymer was that it would bridge the latex compound particulates to improve strength, an entirely different mechanism for the enhancement of strength was explored through a parallel investigation of the release of proteins from cured natural rubber. However, no mechanism was conclusively identified. To address the allergy aspects of NRL, a thorough examination of the release of naturally-occurring latex proteins from cured natural rubber latex glove material was conducted in order to identify mechanisms for eliminating and/or reducing the potential allergens. The initial study examined the release of loaded proteins from cured NR and NR that contained PA in the initial latex compound and the results showed the likelihood of binding between proteins and PA.

A Weakest-Link Approach for Fatigue Limit of 30CrNiMo8 Steels (Preprint)

DTIC Science & Technology

2011-03-01

34Application of a Weakest-Link Concept to the Fatigue Limit of the Bearing Steel Sae 52100 in a Bainitic Condition," Fatigue and Fracture of...AFRL-RX-WP-TP-2011-4206 A WEAKEST-LINK APPROACH FOR FATIGUE LIMIT OF 30CrNiMo8 STEELS (PREPRINT) S. Ekwaro-Osire and H.V. Kulkarni Texas...2011 4. TITLE AND SUBTITLE A WEAKEST-LINK APPROACH FOR FATIGUE LIMIT OF 30CrNiMo8 STEELS (PREPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT

Adhesives, fillers and potting compounds. Second progress report, December 1, 1967--April 1, 1968

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

Lichte, H.W.; Akst, I.B.

1968-12-31

Progress in the development program whose immediate purpose is to reduce set time of a silicone compound is described. Data are presented showing that a formulation of a current RTV silicone rubber with dibutyltin diacetate has a profitably lower set time than the same rubber in the present formulation which uses dibutyltin dilaurate, without increase in probability of either reversion or penalty to other weapons components. Time to set sufficiently to allow the next assembly step is 2 to 4 hours, compared to the 16 to 24 hours presently allowed or the 8 to 12 hours minimum attainable with themore » present formulation. The reduction is of the magnitude set as a goal, the attainment of which would increase production capacity enough to reduce the amount of new construction planned to accommodate weapons assembly programs.« less

Flame resistant elastomeric polymer development. [for use in space shuttle instrument packaging

NASA Technical Reports Server (NTRS)

Howarth, J. T.; Sheth, S. G.; Sidman, K. R.

1975-01-01

Elastomeric products were developed for use in the space shuttle program, and investigations were conducted to improve the properties of elastomers developed in previous programs, and to evaluate the possibility of using lower-cost general purpose polymers. Products were fabricated and processed on conventional processing equipment; these products include: foams based on fluorinated rubber flame-retarded compounds with a density of 20-30 pounds/cubic foot for use as padding and in helmets; foams based on urethane for use in instrument packaging in the space shuttle; flexible and semi-rigid films of fluorinated rubber and neoprene compounds that would not burn in a 70% nitrogen, 30% oxygen atmosphere, and in a 30% nitrogen, 70% oxygen atmosphere, respectively for use in packaging or in laminates; coated fabrics which used both nylon and Kelvar fabric substrates, coated with either fluorinated or neoprene polymer compositions to meet specific levels of flame retardancy; and other flame-resistant materials.

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

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

Muttalib, Siti Nadzirah Abdul, E-mail: sitinadzirah.amn@gmail.com; Othman, Nadras, E-mail: srnadras@usm.my; Ismail, Hanafi, E-mail: ihanafi@usm.my

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 microscopymore » 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.« less

Impact of Selected Parameters on the Fatigue Strength of Splices on Multiply Textile Conveyor Belts

NASA Astrophysics Data System (ADS)

Bajda, Mirosław; Błażej, Ryszard; Hardygóra, Monika

2016-10-01

Splices are the weakest points in the conveyor belt loop. The strength of these joints, and thus their design as well as the method and quality of splicing, determine the strength of the whole conveyor belt loop. A special zone in a splice exists, where the stresses in the adjacent plies or cables differ considerably from each other. This results in differences in the elongation of these elements and in additional shearing stresses in the rubber layer. The strength of the joints depends on several factors, among others on the parameters of the joined belt, on the connecting layer and the technology of joining, as well as on the materials used to make the joint. The strength of the joint constitutes a criterion for the selection of a belt suitable for the operating conditions, and therefore methods of testing such joints are of great importance. This paper presents the method of testing fatigue strength of splices made on multi-ply textile conveyor belts and the results of these studies.

Analysis of longitudinal seismic response of bridge with magneto-rheological elastomeric bearings

NASA Astrophysics Data System (ADS)

Li, Rui; Li, Xi; Wu, Yueyuan; Chen, Shiwei; Wang, Xiaojie

2016-04-01

As the weakest part in the bridge system, traditional bridge bearing is incapable of isolating the impact load such as earthquake. A magneto-rheological elastomeric bearing (MRB) with adjustable stiffness and damping parameters is designed, tested and modeled. The developed Bouc-Wen model is adopted to represent the constitutive relation and force-displacement behavior of an MRB. Then, the lead rubber bearing (LRB), passive MRB and controllable MRB are modeled by finite element method (FEM). Furthermore, two typical seismic waves are adopted as inputs for the isolation system of bridge seismic response. The experiments are carried out to investigate the different response along the bridge with on-off controlled MRBs. The results show that the isolating performance of MRB is similar to that of traditional LRB, which ensures the fail-safe capability of bridge with MRBs under seismic excitation. In addition, the controllable bridge with MRBs demonstrated the advantage of isolating capacity and energy dissipation, because it restrains the acceleration peak of bridge beam by 33.3%, and the displacement of bearing decrease by 34.1%. The shear force of the pier top is also alleviated.

Toxic effects of butyl elastomers on aerobic methane oxidation

NASA Astrophysics Data System (ADS)

Niemann, Helge; Steinle, Lea I.; Blees, Jan H.; Krause, Stefan; Bussmann, Ingeborg; Lehmann, Moritz F.; Treude, Tina

2013-04-01

Large quantities of the potent greenhouse gas methane are liberated into the water column of marine and lacustrine environments where it may be consumed by aerobic methane oxidising bacteria before reaching the atmosphere.The reliable quantification of aerobic methane oxidation (MOx) rates is consequently of paramount importance for estimating methane budgets and to understand the controls on water column methane cycling. A widely used set of methods for measuring MOx rates is based on the incubation of water samples during which the consumption of methane is monitored, for instance with radio-tracer assays. Typically, incubation vessels are sealed with butyl rubber stoppers because these elastomers are essentially impermeable for gases at the relevant time scales. We tested the effect of different stopper materials (unmodified- and halogenated butyl rubber) on MOx activity in environmental samples and in cultures of methane oxidising bacteria. MOx rates in samples sealed with unmodified butyl rubber were > 75% lower compared to parallel incubations with halogenated butyl rubber seals, suggesting inhibiting/toxic effects associated with the use of unmodified butyl elastomers. To further explore the cause of these effects, we analysed aqueous extracts of the different stoppers. Halogenated butyl rubber stoppers appeared to bleed off comparably little amounts of organics. In stark contrast, extracts of unmodified butyl rubber were contaminated with various organic compounds including potential bactericides such as benzyltoluenes, phenylalkanes and benzuothiazoles. We also found tetramethylthiourea, a scavenger of active oxygen species, which may inhibit the MOx pathway.

Effects of Leachate from Crumb Rubber and Zinc in Green Roofs on the Survival, Growth, and Resistance Characteristics of Salmonella enterica subsp. enterica Serovar Typhimurium

PubMed Central

Crampton, Mollee; Ryan, Allayna; Eckert, Cori; Baker, Katherine H.

2014-01-01

The use of green roofs is a growing practice worldwide, particularly in densely populated areas. In an attempt to find new methods for recycling crumb rubber, incorporation of crumb rubber into artificial medium for plant growth in green roofs and similar engineered environments has become an attractive option for the recycling of waste tires. Though this approach decreases waste in landfills, there are concerns about the leaching of zinc and other heavy metals, as well as nutrient and organic compounds, into the environment. The present study analyzed the impact of leachate from crumb rubber and zinc on the growth and viability of Salmonella enterica subsp. enterica serovar Typhimurium. Zinc was chosen for further studies since it has been previously implicated with other biological functions, including biofilm formation, motility, and possible cross-resistance to antimicrobial agents. The study showed that Salmonella can colonize crumb rubber and that crumb rubber extract may provide nutrients that are usable by this bacterium. Salmonella strains with reduced susceptibility (SRS) to zinc were obtained after subculturing in increasing concentrations of zinc. The SRS exhibited differences in gene expression of flux pump genes zntA and znuA compared to that of the parent when exposed to 20 mM added zinc. In biofilm formation studies, the SRS formed less biofilm but was more motile than the parental strain. PMID:24584242

Contact dermatitis caused by a new rubber compound detected in canvas shoes.

PubMed

Hulstaert, Eva; Bergendorff, Ola; Persson, Christina; Goossens, An; Gilissen, Liesbeth; Engfeldt, Malin; Bruze, Magnus; Schuttelaar, Marie L; Meijer, Joost M; Lapeere, Hilde

2018-01-01

In 2015 and 2016, female patients in Flanders consulted a dermatologist because they developed skin lesions after wearing a specific brand of canvas shoes. To identify the culprit allergen in the shoes. Eighteen young females aged 14-22 years presented with itching and erythematous to purple-coloured eczematous lesions on both feet. They were patch tested by 10 dermatologists with the European baseline series. Some patients underwent testing with additional series. Pieces of the shoe fabrics were tested in 11 of 18 patients. Chemical analysis of the shoe materials was performed. Finally, patients were tested with a thin-layer chromatogram of the shoe extracts and dilutions of the suspected rubber compound. All 18 patients showed positive reactions to thiuram mix. Ten of 11 patients reacted to a piece of shoe fabric. Chemical analysis showed the presence of dimethylthiocarbamylbenzothiazole sulfide (DMTBS). No thiurams were detected. Four patients tested with the chromatogram developed positive reactions to DMTBS. Positive reactions to low concentrations were observed in the 4 patients tested with a DMTBS dilution series; one patient reacted to 0.00001% in acetone. DMTBS, the culprit allergen, is a component formed during rubber vulcanization that probably cross-reacts with the thiuram mix. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Liver disease among polyvinyl chloride production workers.

PubMed

Creech, J L; Makk, L

1975-01-31

A protocol for systematic testing of all employees of a chemical plant is presented. This factory manufactures polyvinyl chloride compounds and resins, ABS compounds and resins, and synthetic rubber. The results were reviewed, which led to the discovery of 2 additional cases of angiosarcoma and 11 cases of portal fibrosis. Two of the 11 cases were found to have developed in employees other than polyvinyl chloride production workers.

Effects of different processing techniques on multi-walled carbon nanotubes/silicone rubber nanocomposite on tensile strength properties

NASA Astrophysics Data System (ADS)

Mazlan, N.; Jaafar, M.; Aziz, A.; Ismail, H.; Busfield, J. J. C.

2016-10-01

In this work, two different processing techniques were approached to identify the properties of the multi-walled carbon nanotubes (MWCNT) reinforced polydimethylsiloxane (PDMS). The MWCNT was dispersed in the polymer by using the ultrasonic and twin screw extruder mixer. The final composite showed different manner of dispersed tubes in the silicone rubber matrix. High shear twin screw extruder tends to fragment the tubes during processing compound, which can be observed by scanning electron microscope (SEM). Tensile strength of the extrusion MWCNT/PDMS nanocomposites was found to be higher compared to ultrasonic MWCNT/PDMS nanocomposites.

Elastic MCF Rubber with Photovoltaics and Sensing on Hybrid Skin (H-Skin) for Artificial Skin by Utilizing Natural Rubber: 2nd Report on the Effect of Tension and Compression on the Hybrid Photo- and Piezo-Electricity Properties in Wet-Type Solar Cell Rubber.

PubMed

Shimada, Kunio

2018-06-06

In contrast to ordinary solid-state solar cells, a flexible, elastic, extensible and light-weight solar cell has the potential to be extremely useful in many new engineering applications, such as in the field of robotics. Therefore, we propose a new type of artificial skin for humanoid robots with hybrid functions, which we have termed hybrid skin (H-Skin). To realize the fabrication of such a solar cell, we have continued to utilize the principles of ordinary solid-state wet-type or dye-sensitized solar rubber as a follow-up study to the first report. In the first report, we dealt with both photovoltaic- and piezo-effects for dry-type magnetic compound fluid (MCF) rubber solar cells, which were generated because the polyisoprene, oleic acid of the magnetic fluid (MF), and water served as p- and n- semiconductors. In the present report, we deal with wet-type MCF rubber solar cells by using sensitized dyes and electrolytes. Photoreactions generated through the synthesis of these components were investigated by an experiment using irradiation with visible and ultraviolet light. In addition, magnetic clusters were formed by the aggregation of Fe₃O₄ in the MF and the metal particles created the hetero-junction structure of the semiconductors. In the MCF rubber solar cell, both photo- and piezo-electricity were generated using a physical model. The effects of tension and compression on their electrical properties were evaluated. Finally, we experimentally demonstrated the effect of the distance between the electrodes of the solar cell on photoelectricity and built-in electricity.

40 CFR 428.11 - Specialized definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... AND STANDARDS (CONTINUED) RUBBER MANUFACTURING POINT SOURCE CATEGORY Tire and Inner Tube Plants... black, oils, chemical compounds, fabric and wire used in the manufacture of pneumatic tires and inner... inner tube plants constructed before 1959, discharges from the following: Soapstone solution...

40 CFR 428.11 - Specialized definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... AND STANDARDS (CONTINUED) RUBBER MANUFACTURING POINT SOURCE CATEGORY Tire and Inner Tube Plants... black, oils, chemical compounds, fabric and wire used in the manufacture of pneumatic tires and inner... inner tube plants constructed before 1959, discharges from the following: Soapstone solution...

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.

Morphological and mechanical properties of styrene butadiene rubber/nano copper nanocomposites

NASA Astrophysics Data System (ADS)

Harandi, Maryam Hadizadeh; Alimoradi, Fakhrodin; Rowshan, Gholamhussein; Faghihi, Morteza; Keivani, Maryam; Abadyan, Mohamadreza

In this research, rubber based nanocomposites with presence of nanoparticle has been studied. Styrene butadiene rubber (SBR)/nanocopper (NC) composites were prepared using two-roll mill method. Transmission electron microscope (TEM) and scanning electron microscope (SEM) images showed proper dispersion of NC in the SBR matrix without substantial agglomeration of nanoparticles. To evaluate the curing properties of nanocomposite samples, swelling and cure rheometric tests were conducted. Moreover, the rheological studies were carried out over a range of shear rates. The effect of NC particles was examined on the thermal behavior of the SBR using thermal gravimetric analysis (TGA). Furthermore, tensile tests were employed to investigate the capability of nanoparticles to enhance mechanical behavior of the compounds. The results showed enhancement in tensile properties with incorporation of NC to SBR matrix. Moreover, addition of NC increased shear viscosity and curing time of SBR composites.

Butyl rubber O-ring seals: Revision of test procedures for stockpile materials

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

Domeier, L.A.; Wagter, K.R.

1996-12-01

Extensive testing showed little correlation between test slab and O-ring performance. New procedures, comparable to those used with the traditional test slabs, were defined for hardness, compression set, and tensile property testing on sacrificial O-ring specimens. Changes in target performance values were made as needed and were, in one case, tightened to reflect the O-ring performance data. An additional study was carried out on O-ring and slab performance vs cure cycle and showed little sensitivity of material performance to large changes in curing time. Aging and spectra of certain materials indicated that two sets of test slabs from current vendormore » were accidently made from EPDM rather than butyl rubber. Random testing found no O-rings made from EPDM. As a result, and additional spectroscope test will be added to the product acceptance procedures to verify the type of rubber compound used.« less

Biodegradation of cis-1,4-Polyisoprene Rubbers by Distinct Actinomycetes: Microbial Strategies and Detailed Surface Analysis

PubMed Central

Linos, Alexandros; Berekaa, Mahmoud M.; Reichelt, Rudolf; Keller, Ulrike; Schmitt, Jürgen; Flemming, Hans-Curt; Kroppenstedt, Reiner M.; Steinbüchel, Alexander

2000-01-01

Several actinomycetes isolated from nature were able to use both natural rubber (NR) and synthetic cis-1,4-polyisoprene rubber (IR) as a sole source of carbon. According to their degradation behavior, they were divided into two groups. Representatives of the first group grew only in direct contact to the rubber substrate and led to considerable disintegration of the material during cultivation. The second group consisted of weaker rubber decomposers that did not grow adhesively, as indicated by the formation of clear zones (translucent halos) around bacterial colonies after cultivation on NR dispersed in mineral agar. Taxonomic analysis of four selected strains based on 16S rRNA similarity examinations revealed two Gordonia sp. strains, VH2 and Kb2, and one Mycobacterium fortuitum strain, NF4, belonging to the first group as well as one Micromonospora aurantiaca strain, W2b, belonging to the second group. Schiff's reagent staining tests performed for each of the strains indicated colonization of the rubber surface, formation of a bacterial biofilm, and occurrence of compounds containing aldehyde groups during cultivation with NR latex gloves. Detailed analysis by means of scanning electron microscopy yielded further evidence for the two different microbial strategies and clarified the colonization efficiency. Thereby, strains VH2, Kb2, and NF4 directly adhered to and merged into the rubber material, while strain W2b produced mycelial corridors, especially on the surface of IR. Fourier transform infrared spectroscopy comprising the attenuated total reflectance technique was applied on NR latex gloves overgrown by cells of the Gordonia strains, which were the strongest rubber decomposers. Spectra demonstrated the decrease in number of cis-1,4 double bonds, the formation of carbonyl groups, and the change of the overall chemical environment, indicating that an oxidative attack at the double bond is the first metabolic step of the biodegradation process. PMID:10742254

Paint and Surface Preparation Training Program for Shipyard Personnel

DTIC Science & Technology

1979-01-01

major anti- fouling ingredient in the various coatings which are used on shipbottoms -- bituminous, vinyl, and chlorinated rubber. Organotin compounds ...Improper cleaning of surface or spray gun; dirty work area. Remedy: In most cases, sanding and recoating is sufficient. Blasting may be indicated in... compounds . When using air-fed respirators, the source of air must be monitored and controlled. It must meet specifications defining cleanliness and minimal

40 CFR 60.542 - Standards for volatile organic compounds.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Rubber Tire Manufacturing Industry § 60.542 Standards for volatile organic compounds. (a) On and after... duration of the compliance period: (A) 3,870 kg (8,531 lb) of VOC per 28 days, (B) 4,010 kg (8,846 lb) of VOC per 29 days, (C) 4,150 kg (9,149 lb) of VOC per 30 days, (D) 4,280 kg (9,436 lb) of VOC per 31...

Calibration of silicone rubber rods as passive samplers for pesticides at two different flow velocities: Modeling of sampling rates under water boundary layer and polymer control.

PubMed

Martin, Alexis; Margoum, Christelle; Jolivet, Antoine; Assoumani, Azziz; El Moujahid, Bachir; Randon, Jérôme; Coquery, Marina

2018-04-01

There is a need to determine time-weighted average concentrations of polar contaminants such as pesticides by passive sampling in environmental waters. Calibration data for silicone rubber-based passive samplers are lacking for this class of compounds. The calibration data, sampling rate (R s ), and partition coefficient between silicone rubber and water (K sw ) were precisely determined for 23 pesticides and 13 candidate performance reference compounds (PRCs) in a laboratory calibration system over 14 d for 2 water flow velocities, 5 and 20 cm s -1 . The results showed that an in situ exposure duration of 7 d left a silicone rubber rod passive sampler configuration in the linear or curvilinear uptake period for 19 of the pesticides studied. A change in the transport mechanism from polymer control to water boundary layer control was observed for pesticides with a log K sw of approximately 3.3. The PRC candidates were not fully relevant to correct the impact of water flow velocity on R s . We therefore propose an alternative method based on an overall resistance to mass transfer model to adjust R s from laboratory experiments to in situ hydrodynamic conditions. We estimated diffusion coefficients (D s ) and thickness of water boundary layer (δ w ) as adjustable model parameters. Log D s values ranged from -12.13 to -10.07 m 2  s -1 . The estimated δ w value showed a power function correlation with water flow velocity. Environ Toxicol Chem 2018;37:1208-1218. © 2017 SETAC. © 2017 SETAC.

Effects of habitat management on different feeding guilds of herbivorous insects in cacao agroforestry systems.

PubMed

Novais, Samuel M A; Macedo-Reis, Luiz E; DaRocha, Wesley D; Neves, Frederico S

2016-06-01

Human pressure on natural habitats increases the importance of agroforests for biodiversity conservation. The objective of this study was to evaluate the role of cacao traditional cultivation system (CTCS) on the conservation of the herbivorous insect community when compared with a monodominant rubber agroforest, a type of agricultural system for cacao cultivation. The insects were sampled in three habitats in Southeastern Bahia, Brazil: native forests, CTCS and rubber agroforests. In each habitat, 18 plots of 10 m2 were established, and the structural measures were collected and herbivorous insects were sampled with a Malaise/window trap. The diversity of folivorous decreased with the simplification of vegetation structure, but species composition was similar among habitats. In addition to a decrease in the availability of resources in monodominant rubber agroforests, the latex present in these systems have limited the occurrence of species that cannot circumvent latex toxicity. The diversity of sap-sucking insects was similar among habitats, but species composition was similar only in the CTCS and native forest, and it was different in the rubber agroforest. We observed turnover and a higher frequency of individuals of the family Psyllidae in the rubber agroforest. The biology and behavior of Psyllids and absence of natural enemies enable their diversity to increase when they are adapted to a new host. We observed a shift in the composition of xylophagous insects in the rubber agroforest compared to that in other habitats. Moreover, this agroforest has low species richness, but high individual abundance. Latex extraction is likely an important additional source of volatile compounds discharged into the environment, and it increases the attraction and recruitment of coleoborers to these sites. We concluded that CTCS has an herbivorous insect community with a structure similar to the community found in native forests of the region, and they present a more interesting conservation strategy when compared to rubber agroforests. We also emphasized the potential risk of local pest outbreaks in rubber agroforests for both the rubber and associated cacao trees.

Interference in adhesion of bacteria and yeasts isolated from explanted voice prostheses to silicone rubber by rhamnolipid biosurfactants.

PubMed

Rodrigues, L R; Banat, I M; van der Mei, H C; Teixeira, J A; Oliveira, R

2006-03-01

The effects and extent of adhesion of four different bacterial and two yeast strains isolated from explanted voice prostheses to silicone rubber with and without an adsorbed rhamnolipid biosurfactant layer obtained from Pseudomonasaeruginosa DS10-129 was studied. The ability of rhamnolipid biosurfactant to inhibit adhesion of micro-organisms to silicone rubber was investigated in a parallel-plate flow chamber. The anti-adhesive activity of the biosurfactant at different concentrations was significant against all the strains and depended on the micro-organism tested. The results showed an effective reduction in the initial deposition rates, and the number of bacterial cells adhering after 4 h, for all micro-organisms tested at the 4 g l(-1) undiluted rhamnolipid solution. Maximum initial reduction of adhesion rate (an average of 66%) occurred for Streptococcus salivarius GB 24/9 and Candida tropicalis GB 9/9. The number of cells adhering after 4 h on silicone rubber conditioned with biosurfactant was reduced to 48% for Staphylococcus epidermidis GB 9/6, Strep. salivarius GB 24/9, Staphylococcus aureus GB 2/1 and C. tropicalis GB 9/9 in comparison to controls. Perfusing the flow chamber with biosurfactant containing solution followed by the passage of a liquid-air interface, to investigate detachment of micro-organisms adhering to silicone rubber, produced high detachment (96%) of adhered cells for all micro-organisms studied, except for Staph. aureus GB 2/1 (67%). It is concluded that biosurfactant represent suitable compounds that should be considered in developing future strategies to prevent the microbial colonization of silicone rubber voice prostheses.

The "weakest link" as an indicator of cognitive vulnerability differentially predicts symptom dimensions of anxiety in adolescents in China.

PubMed

Wang, Junyi; Wang, Danyang; Cui, Lixia; McWhinnie, Chad M; Wang, Li; Xiao, Jing

2017-08-01

This multiwave longitudinal study examined the cognitive vulnerability-stress component of hopelessness theory to differentially predict symptom dimensions of anxiety using a "weakest link" approach in a sample of adolescents from Hunan Province, China. Baseline and 6-month follow-up data were obtained from 553 middle-school students. During an initial assessment, participants completed measures of assessing their weakest links, anxious symptoms, and the occurrence of stress. Participants subsequently completed measures assessing stress, and anxious symptoms one a month for six months. Higher weakest link scores were associated with greater increases in the harm avoidance and separation anxiety/panic dimensions, but not the physical or social anxiety dimension, of anxious symptoms following stress in Chinese adolescents. These results support the applicability of the "weakest link" approach, derived from hopelessness theory, in Chinese adolescents. Weakest link scores as cognitive vulnerability factors may play a role in the development of anxious symptoms, especially in the cognitive dimensions (e.g., harm avoidance and separation anxiety/panic). Our findings also have potential value in explaining the effectiveness of cognitive relevant therapy in treating the cognitive dimensions of anxious symptoms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quality improvement of pyrolysis oil from waste rubber by adding sawdust.

PubMed

Wang, Wen-liang; Chang, Jian-min; Cai, Li-ping; Shi, Sheldon Q

2014-12-01

This work was aimed at improving the pyrolysis oil quality of waste rubber by adding larch sawdust. Using a 1 kg/h stainless pyrolysis reactor, the contents of sawdust in rubber were gradually increased from 0%, 50%, 100% and 200% (wt%) during the pyrolysis process. Using a thermo-gravimetric (TG) analyzer coupled with Fourier transform infrared (FTIR) analysis of evolving products (TG-FTIR), the weight loss characteristics of the heat under different mixtures of sawdust/rubber were observed. Using the pyrolysis-gas chromatography (GC)-mass spectrometry (Py-GC/MS), the vapors from the pyrolysis processes were collected and the compositions of the vapors were examined. During the pyrolysis process, the recovery of the pyrolysis gas and its composition were measured in-situ at a reaction temperature of 450 °C and a retaining time of 1.2s. The results indicated that the efficiency of pyrolysis was increased and the residual carbon was reduced as the percentage of sawdust increased. The adding of sawdust significantly improved the pyrolysis oil quality by reducing the polycyclic aromatic hydrocarbons (PAHs) and nitrogen and sulfur compounds contents, resulting in an improvement in the combustion efficiency of the pyrolysis oil. Copyright © 2014 Elsevier Ltd. All rights reserved.

Potting procedure for electronic components

NASA Technical Reports Server (NTRS)

Rubino, A. G.; Zimmerman, J.

1977-01-01

Potting process is modified to effect a match more closely between embedded electronic components, potting mediums, and thermal environment. Application of room-temperature vulcanizing silicone rubber band cured in modified thermal cycle minimizes coil-to-resin adhesion and thus lowers stresses between transformer and potting compound.

Industrial viable process of making nanoparticles of various shapes and interior structures

NASA Astrophysics Data System (ADS)

Wang, Xiaorong

2008-03-01

Over the past 10 years, we attempted to develop industrial viable processes which were of significance in manufacturing the nanoparticles in good quality and large volume. Our effort relied on the self-assembly concepts of block macromolecules in solutions to prepare particles with a hard core made of crosslinked plastics and a soft shell made of low Tg elastomer. Depending on the type and microstructure of the copolymers, the solvent concentration and other process parameters chosen, a variety of shell-core nano-particles of different shapes (spheres, hollow spheres, ellipsoids, cylinders, linear and branched strings, disks and etc.) and sizes (5-100 nm diameter) were reproducibly synthesized. Scale-up studies led to an optimization of the manufacturing process and the production of nanoparticles in large quantities for various product application efforts. The unique performance of those nanoparticles as performance tuning additives and novel rubber reinforcing elements was explored in rubber compounds. This review describes the synthesis methods used to produce the polymer nanoparticles, the technology to modify the particles through functionalization, the means to optimize their performance for specific applications, and the methods to use those particles in rubber compounds. Collaborators: Victor J. Foltz, Kurasch Jessica, Chenchy J. Lin, Jeff Magestrelli, Sandra Warren, Alberto Scuratti, James E. Hall, Jim Krom, Mindaugas Rackaitis, Michael W. Hayes, Pat Sadhukhan, Georg G. A. Bohm

Core-based intrinsic fiber-optic absorption sensor for the detection of volatile organic compounds

NASA Astrophysics Data System (ADS)

Klunder, Gregory L.; Russo, Richard E.

1995-03-01

A core-based intrinsic fiber-optic absorption sensor has been developed and tested for the detection of volatile organic compounds. The distal ends of transmitting and receiving fibers are connected by a small cylindrical section of an optically clear silicone rubber. The silicone rubber acts both as a light pipe and as a selective membrane into which the analyte molecules can diffuse. The sensor has been used to detect volatile organics (trichloroethylene, 1,1-dichloroethylene, and benzene) in both aqueous solutions and in the vapor phase or headspace. Absorption spectra obtained in the near-infrared (near-IR) provide qualitative and quantitative information about the analyte. Water, which has strong broad-band absorption in the near-IR, is excluded from the spectra because of the hydrophobic properties of the silicone rubber. The rate-limiting step is shown to be the diffusion through the Nernstian boundary layer surrounding the sensor and not the diffusion through the silicone polymer. The rate of analyte diffusion into the sensor, as measured by the t(sub 90) values (the time required for the sensor to reach 90% of the equilibrium value), is 30 min for measurements in aqueous solutions and approximately 3 min for measurements made in the headspace. The limit of detection obtained with this sensor is approximately 1.1 ppm for trichloroethylene in an aqueous solution.

Railroad Regulation: Changes in Freight Railroad Rates from 1997 through 2000

DTIC Science & Technology

2002-06-01

Routes, 1990–2000 19 Figure 5: Real Rail Rates for Plastic Materials or Synthetic Fibers, Resins, or Rubbers, Selected Short-Distance Routes, 1990–2000...Compounds, Selected Short-, Medium-, and Long-Distance Routes, 1990–2000 39 Figure 14: Real Rail Rates for Plastic Materials or Synthetic Fibers, Resins...Transportation Board to determine rates for coal, grain (wheat and corn), chemicals (potassium and sodium compounds and plastic materials or synthetic

Effect of Fermentation Broths on Performance of Hydrophobic Zeolite-Silicone Rubber Mixed Matrix Pervaporation Membranes

EPA Science Inventory

Fermentative organisms produce a range of compounds in addition to the desired product. For example, in addition to ethanol, standard yeast produce longer straight-chained and branched alcohols and organic acids. Additionally, biomass pretreatment process, particularly acid-bas...

Comparative numerical study on the optimal vulcanization of rubber compounds through traditional curing and microwaves

NASA Astrophysics Data System (ADS)

Milani, Gabriele; Milani, Federico

2012-12-01

The main problem in the industrial production process of thick EPM/EPDM elements is constituted by the different temperatures which undergo internal (cooler) and external regions. Indeed, while internal layers remain essentially under-vulcanized, external coating is always over-vulcanized, resulting in an overall average tensile strength insufficient to permit the utilization of the items in several applications where it is required a certain level of performance. Possible ways to improve rubber output mechanical properties include a careful calibration of exposition time and curing temperature in traditional heating or a vulcanization through innovative techniques, such as microwaves. In the present paper, a comprehensive numerical model able to give predictions on the optimized final mechanical properties of vulcanized 2D and 3D thick rubber items is presented and applied to a meaningful example of engineering interest. A detailed comparative numerical study is finally presented in order to establish pros and cons of traditional vulcanization vs microwaves curing.

Shock tunnel studies of scramjet phenomena 1994

NASA Technical Reports Server (NTRS)

1995-01-01

A new expansion tube facility has been built, and is in the process of being commissioned. It has a bore of 90 mm, and has been designed for peak rupture pressures of 100 Mpa. It is configured with multiple sections and diaphragm location stations to give optimized performance over a range of sub and superorbital conditions. It has a compound piston arrangement for a two stage compression, designed to maximize the length of shock expansion tube which can be driven within a fixed total facility length. Experiments have been successfully performed with a dummy first stage piston, and a rubber energy absorbing brake. The results agree well with a one-dimensional stress wave model of the piston impacting on the rubber, and codes for piston motion. Strain of the rubber is restricted to approximately 20 percent at which level no damage is to be expected in the buffer material, and none has been observed, indicating that the mechanism will be fully reuseable.

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

Hydrothermal carbonization of typical components of municipal solid waste for deriving hydrochars and their combustion behavior.

PubMed

Lin, Yousheng; Ma, Xiaoqian; Peng, Xiaowei; Yu, Zhaosheng

2017-11-01

In this work, five typical components were employed as representative pseudo-components to indirectly complete previous established simulation system during hydrothermal carbonization (HTC) of municipal solid waste. The fuel characteristics and combustion behavior of HTC-derived hydrochars were evaluated. Results clearly illustrated that the energy ranks of hydrochars were upgraded after HTC. For paper and wood, superior combustion performances of their hydrochars could achieve under suitable conditions. While for food, none positive enrichments on combustion loss rate were observed for hydrochars due to its high solubilization and decomposition under hot compressed water. It was noteworthy that a new weight loss peak was detected for paper and food, suggesting that new compounds were formed. For rubber, the HTC process made the properties of styrene butadiene rubber more close to natural rubber. Therefore, the first peak of hydrochars became significantly intense. While for plastic, only physical changes of polypropylene and polyethylene were observed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Artificial Turf: Contested Terrains for Precautionary Public Health with Particular Reference to Europe?

PubMed Central

Watterson, Andrew

2017-01-01

Millions of adults, children and teenagers use artificial sports pitches and playgrounds globally. Pitches are artificial grass and bases may be made up of crumb rubber from recycled tires or new rubber and sand. Player injury on pitches was a major concern. Now, debates about health focus on possible exposure and uptake of chemicals within pitch and base materials. Research has looked at potential risks to users from hazardous substances such as metals, volatile organic compounds, polycyclic aromatic hydrocarbons including benzo (a) (e) pyrenes and phthalates: some are carcinogens and others may be endocrine disruptors and have developmental reproductive effects. Small environmental monitoring and modelling studies, often with significant data gaps about exposure, range of substances monitored, occupational exposures, types of surfaces monitored and study length across seasons, indicated little risk to sports people and children but some risk to installation workers. A few, again often small, studies indicated potentially harmful human effects relating to skin, respiration and cancers. Only one widely cited biomonitoring study has been done and no rigorous cancer epidemiological studies exist. Unravelling exposures and uptake over decades may prove complex. European regulators have strengthened controls over crumb rubber chemicals, set different standards for toys and crumb rubber pitches. Bigger US studies now underway attempting to fill some of the data gaps will report between 2017 and 2019. Public health professionals in the meantime may draw on established principles to support greater caution in setting crumb rubber exposure limits and controls. PMID:28895924

The mechanical behaviour of NBR/FEF under compressive cyclic stress strain

NASA Astrophysics Data System (ADS)

Mahmoud, W. E.; El-Eraki, M. H. I.; El-Lawindy, A. M. Y.; Hassan, H. H.

2006-06-01

Acrylonitrile butadiene rubber compounds filled with different concentrations of fast extrusion furnace (FEF) carbon black were experimentally investigated. The stress-strain curves of the composites were studied, which suggest good filler-matrix adhesion. The large reinforcement effect of the filler followed the Guth model for non-spherical particles. The effect of FEF carbon black on the cyclic fatigue and hysteresis was also examined. The loading and unloading stress-strain relationships for any cycle were described by applying Ogden's model for rubber samples. The dissipation energy that indicates the vibration damping capacity for all samples was determined. A simple model was proposed, to investigate the relation between maximum stress and the number of cyclic fatigue.

Integrated circuit package with lead structure and method of preparing the same

NASA Technical Reports Server (NTRS)

Kennedy, B. W. (Inventor)

1973-01-01

A beam-lead integrated circuit package assembly including a beam-lead integrated circuit chip, a lead frame array bonded to projecting fingers of the chip, a rubber potting compound disposed around the chip, and an encapsulating molded plastic is described. The lead frame array is prepared by photographically printing a lead pattern on a base metal sheet, selectively etching to remove metal between leads, and plating with gold. Joining of the chip to the lead frame array is carried out by thermocompression bonding of mating goldplated surfaces. A small amount of silicone rubber is then applied to cover the chip and bonded joints, and the package is encapsulated with epoxy resin, applied by molding.

Accelerated aging and stabilization of radiation-vulcanized EPDM rubber

NASA Astrophysics Data System (ADS)

Basfar, A. A.; Abdel-Aziz, M. M.; Mofti, S.

2000-03-01

The effect of different antioxidants and their mixtures on the thermal aging and accelerated weathering of γ-radiation vulcanized EPDM rubber in presence of crosslinking coagent, was investigated. The compounds used were either a synergistic blend of phenolic and phosphite antioxidants, i.e. 1:4 Irganox 1076: Irgafos 168 or a blend of arylamine and quinoline type antioxidants, i.e. 1:1 IPPD: TMQ, at fixed concentration. Tinuvin 622 LD hindered amine light stabilized (HALS) was also used. The response was evaluated by the tensile strength and elongation at break for irradiated samples after thermal aging at 100°C for 28 days and accelerated weathering (Xenon test) up to 200 h.

The Effect of Fermentation Broth Components on Performance of High Silica ZSM-5/Silicone Rubber Mixed Matrix Membranes

EPA Science Inventory

Fermentative organisms produce a range of compounds in addition to the desired product. For example, in addition to ethanol, standard yeast produces longer straight-chained and branched alcohols and organic acids. Additionally, biomass pretreatment process, particularly acid-base...

Adsorptive desulfurization with metal-organic frameworks: A density functional theory investigation

NASA Astrophysics Data System (ADS)

Chen, Zhiping; Ling, Lixia; Wang, Baojun; Fan, Huiling; Shangguan, Ju; Mi, Jie

2016-11-01

The contribution of each fragment of metal-organic frameworks (MOFs) to the adsorption of sulfur compounds were investigated using density functional theory (DFT). The involved sulfur compounds are dimethyl sulfide (CH3SCH3), ethyl mercaptan (CH3CH2SH) and hydrogen sulfide (H2S). MOFs with different organic ligands (NH2-BDC, BDC and NDC), metal centers structures (M, M-M and M3O) and metal ions (Zn, Cu and Fe) were used to study their effects on sulfur species adsorption. The results revealed that, MOFs with coordinatively unsaturated sites (CUS) have the strongest binding strength with sulfur compounds, MOFs with NH2-BDC substituent group ligand comes second, followed by that with saturated metal center, and the organic ligands without substituent group has the weakest adsorption strength. Moreover, it was also found that, among different metal ions (Fe, Zn and Cu), MOFs with unsaturated Fe has the strongest adsorption strength for sulfur compounds. These results are consistent with our previous experimental observations, and therefore provide insights on the better design of MOFs for desulfurization application.

Nanocomposites of nitrile (NBR) rubber with multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Warasitthinon, Nuthathai

Nanotechnology offers the promise of creating new materials with enhanced performance. There are different kinds of fillers used in rubber nanocomposites, such as carbon black, silica, carbon fibers, and organoclays. Carbon nanotube reinforced elastomers have potential for improved rubber properties in aggressive environments. The first chapter is an introduction to the literature. The second chapter investigated the incorporation of multi-walled carbon nanotubes (MWCNTs) into rubber matrix for potential use in high temperature applications. The vulcanization kinetics of acrylonitrile butadiene rubber (NBR) reinforced with multi-walled carbon nanotubes was investigated. The vulcanized NBR rubber with different loading percentages of MWCNTs was also compared to NBR reinforced with carbon black N330. The optimum curing time at 170°C (T90) was found to decrease with increasing content of MWCNTs. Increased filler loading of both carbon black and MWCNTs gave higher modulus and strength. The MWCNTs filled materials gave better retention of modulus and tensile strength at high temperatures, but lower strength as compared to the carbon black filled samples. In the third chapter, carbon black (CB, 50phr) content in nitrile rubber (NBR) nanocomposites was partially replaced by multi-walled carbon nanotubes (MWCNTs). NBR/CB/CNTs nanocomposites with varying ratio of CB/CNTs (50/0 phr to 40/10 phr) were formulated via the melt-mixing method using an internal mixer. The reinforcing effect of single filler (CB) and mixture of fillers (CB and CNTs) on the properties of NBR nanocomposites was investigated. The cure kinetics and bound rubber content were analyzed using rheometry and solvent swelling method. In addition, mechanical behavior at both room temperature and high temperature (350°F/ 121°C) were examined. The scorch time and curing time values showed that there was no significant effect on the curing behavior of NBR nanocomposites after the partial replacement of CB with CNTs. It was observed that bound rubber content decreased with increase in CNT content for NBR/CB/CNTs nanocomposites above a loading of 1 phr CNT. In the fourth chapter, the effect of another carbon filler, fullerene, on the properties of HNBR was studied. Fullerenes are conductive and thermally stable due to their three dimensional aromaticity and high reactivity. In this work, the effect of fullerenes (C60) on the properties of HNBR rubber for potential use in aggressive environments was investigated. The vulcanized HNBR rubber with different filler loadings of fullerenes was compared with carbon black (N330). The static mechanical, dynamic mechanical and rheological behavior of the compounds was investigated, along with the vulcanization kinetics study. Increased filler loading of both carbon black and fullerene gave higher modulus and strength. The fullerene filled materials showed improved failure properties.

Effect of Quaternary Ammonium Salts with Fluorine Atoms on Selected Weed Species.

PubMed

Biczak, Robert; Pawłowska, Barbara; Płatkowski, Maciej; Stręk, Michał; Telesiński, Arkadiusz

2017-04-01

This study investigated the effects of four structurally different quaternary ammonium salts (QASs), i.e., tetrabutylammonium tetrafluoroborate [TBA][BF 4 ], tetrahexylammonium tetrafluoroborate [THA][BF 4 ], tetrabutylammonium hexafluorophosphate [TBA][PF 6 ], and tetrahexylammonium hexafluorophosphate [THA][PF 6 ], on the growth and development of three weed species: gallant soldier (Galinsoga parviflora Cav.), white goosefoot (Chenopodium album L.) and common sorrel (Rumex acetosa L.). The examined compounds were applied in the form of foliar spraying and soil application. Strong herbicidal properties of the examined compounds were demonstrated in case of their soil application. Growth inhibition of plant shoots and roots was greater with soil application than with foliar treatment. The strongest herbicidal activity of compounds was demonstrated with [TBA][BF 4 ] have demonstrated [TBA][BF 4 ] and [TBA][PF 6 ] applied to the soil, while [THA][BF 4 ] demonstrated the weakest herbicidal action. The increased concentration of applied QASs caused a decrease in the assimilation pigments, change in dry weight content and inhibition of length of shoots and roots.

Sensory and chemical investigations on the effect of oven cooking on warmed-over flavour development in chicken meat.

PubMed

Byrne, D V; Bredie, W L P; Mottram, D S; Martens, M

2002-06-01

Descriptive sensory profiling was carried out to evaluate the effect of oven-cooking temperature (160, 170, 180, 190 °C) on warmed-over flavour (WOF) development in cooked, chill-stored (at 4 °C for 0, 1, 2 and 4 days) and reheated chicken patties, derived from M. pectoralis major. In addition, gas chromatography-mass spectrometry (GC-MS) was carried out on a representative sub-set (160, 180, 190(o)C, stored at 4 °C for 0, 1, 4 days) of the meat samples used in sensory profiling. The effects of cooking and WOF in the sensory and chemical data were analysed using multivariate ANOVA-Partial Least Squares Regression (APLSR). Descriptive profiling indicated that WOF development was described by an increase of 'rancid' and 'sulphur/rubber' sensory notes and a concurrent decrease of chicken 'meaty' characteristics. Increasing cooking temperature resulted in meat samples with a more 'roasted', 'toasted' and 'bitter' sensory nature. Moreover, the 'roasted' character of the meat samples was also related to WOF development. Analysis of the volatile compounds from the chicken patties showed a rapid development of lipid oxidation derived compounds with chill-storage. Such compounds most likely contributed to the 'rancid' aspect of WOF development. Moreover, changes in sulphur-containing compounds were also related to WOF development and were proposed as additional participants in the lipid oxidation reactions. The sensory effects of these compounds were mainly described by the 'sulphur/rubber' note associated with WOF development. Overall, cooking temperature was found to increase the formation of Maillard-derived compounds, however, these did not appear to inhibit WOF development in the chicken patties.

Quality improvement of pyrolysis oil from waste rubber by adding sawdust

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

Wang, Wen-liang; Chang, Jian-min, E-mail: cjianmin@bjfu.edu.cn; Cai, Li-ping

Highlights: • Rubber-pyrolysis oil is difficult to be fuel due to high proportion of PAHs. • The efficiency of pyrolysis was increased as the percentage of sawdust increased. • The adding of sawdust improved pyrolysis oil quality by reducing the PAHs content. • Adding sawdust reduced nitrogen/sulfur in oil and was easier to convert to diesel. - Abstract: This work was aimed at improving the pyrolysis oil quality of waste rubber by adding larch sawdust. Using a 1 kg/h stainless pyrolysis reactor, the contents of sawdust in rubber were gradually increased from 0%, 50%, 100% and 200% (wt%) during themore » pyrolysis process. Using a thermo-gravimetric (TG) analyzer coupled with Fourier transform infrared (FTIR) analysis of evolving products (TG–FTIR), the weight loss characteristics of the heat under different mixtures of sawdust/rubber were observed. Using the pyrolysis–gas chromatography (GC)–mass spectrometry (Py–GC/MS), the vapors from the pyrolysis processes were collected and the compositions of the vapors were examined. During the pyrolysis process, the recovery of the pyrolysis gas and its composition were measured in-situ at a reaction temperature of 450 °C and a retaining time of 1.2 s. The results indicated that the efficiency of pyrolysis was increased and the residual carbon was reduced as the percentage of sawdust increased. The adding of sawdust significantly improved the pyrolysis oil quality by reducing the polycyclic aromatic hydrocarbons (PAHs) and nitrogen and sulfur compounds contents, resulting in an improvement in the combustion efficiency of the pyrolysis oil.« less

Adsorptive removal of hydrophobic organic compounds by carbonaceous adsorbents: a comparative study of waste-polymer-based, coal-based activated carbon, and carbon nanotubes.

PubMed

Lian, Fei; Chang, Chun; Du, Yang; Zhu, Lingyan; Xing, Baoshan; Liu, Chang

2012-01-01

Adsorption of the hydrophobic organic compounds (HOCs) trichloroethylene (TCE), 1,3-dichlorobenzene (DCB), 1,3-dinitrobenzene (DNB) and gamma-hexachlorocyclohexane (HCH) on five different carbonaceous materials was compared. The adsorbents included three polymer-based activated carbons, one coal-based activated carbon (F400) and multiwalled carbon nanotubes (MWNT). The polymer-based activated carbons were prepared using KOH activation from waste polymers: polyvinyl chloride (PVC), polyethyleneterephthalate (PET) and tire rubber (TR). Compared with F400 and MWNT, activated carbons derived from PVC and PET exhibited fast adsorption kinetics and high adsorption capacity toward the HOCs, attributed to their extremely large hydrophobic surface area (2700 m2/g) and highly mesoporous structures. Adsorption of small-sized TCE was stronger on the tire-rubber-based carbon and F400 resulting from the pore-filling effect. In contrast, due to the molecular sieving effect, their adsorption on HCH was lower. MWNT exhibited the lowest adsorption capacity toward HOCs because of its low surface area and characteristic of aggregating in aqueous solution.

Single Stage Silicone Border Molded Closed Mouth Impression Technique-Part II.

PubMed

Solomon, E G R

2011-09-01

Functioning of a complete denture depends to a great extent on the impression technique. Several impression techniques have been described in the literature since the turn of this century when Greene [Clinical courses in dental prothesis, 1916] brothers introduced the first scientific system of recording dental impression. Advocates of each technique have their own claim of superiority over the other. The introduction of elastomeric impression materials [Skinner and Cooper, J Am Dent Assoc 51:523-536, 1955] has made possible new techniques of recording impression for complete denture construction. These rubber like materials are of two types; one has a polysulfide base and is popularily known as polysulfide rubber (Thiokol and Mercaptan). The other variety has a silicone base known as silicone rubber or silicone elastomer. Silicone elastomers are available in four different consistencies; a thin easy flowing light bodied material,a creamy medium bodied material, a highly viscous heavy bodied material and a kneadable putty material. This paper describes an active closed mouth impression technique with one stage border molding using putty silicone material as a substitute for low fusing compound.

Evaluation of peptides release using a natural rubber latex biomembrane as a carrier.

PubMed

Miranda, M C R; Borges, F A; Barros, N R; Santos Filho, N A; Mendonça, R J; Herculano, R D; Cilli, E M

2018-05-01

The biomembrane natural (NRL-Natural Rubber Latex), manipulated from the latex obtained from the rubber tree Hevea brasiliensis, has shown great potential for application in biomedicine and biomaterials. Reflecting the biocompatibility and low bounce rate of this material, NRL has been used as a physical barrier to infectious agents and for the controlled release of drugs and extracts. The aim of the present study was to evaluate the incorporation and release of peptides using a latex biomembrane carrier. After incorporation, the release of material from the membrane was observed using spectrophotometry. Analyses using HPLC and mass spectroscopy did not confirm the release of the antimicrobial peptide [W 6 ]Hylin a1 after 24 h. In addition, analysis of the release solution showed new compounds, indicating the degradation of the peptide by enzymes contained in the latex. Additionally, the release of a peptide with a shorter sequence (Ac-WAAAA) was evaluated, and degradation was not observed. These results showed that the use of NRL as solid matrices as delivery systems of peptide are sequence dependent and could to be evaluated for each sequence.

Studies on Stress-Strain Relationships of Polymeric Materials Used in Space Applications

NASA Technical Reports Server (NTRS)

Jana, Sadhan C.; Freed, Alan

2002-01-01

A two-year research plan was undertaken in association with Polymers Branch, NASA Glenn Research Center, to carry out experimental and modeling work relating stress and strain behavior of polymeric materials, especially elastomers and vulcanized rubber. An experimental system based on MTS (Mechanical Testing and Simulation) A/T-4 test facility environment has been developed for a broader range of polymeric materials in addition to a design of laser compatible temperature control chamber for online measurements of various strains. Necessary material processing has been accomplished including rubber compounding and thermoplastic elastomer processing via injection molding. A broad suite of testing methodologies has been identified to reveal the complex non-linear mechanical behaviors of rubbery materials when subjected to complex modes of deformation. This suite of tests required the conceptualization, design and development of new specimen geometries, test fixtures, and test systems including development of a new laser based technique to measure large multi-axial deformations. Test data has been generated for some of these new fixtures and has revealed some complex coupling effects generated during multi-axial deformations. In addition, fundamental research has been conducted concerning the foundation principles of rubber thermodynamics and resulting theories of rubber elasticity. Studies have been completed on morphological properties of several thermoplastic elastomers. Finally, a series of steps have been identified to further advance the goals of NASA's ongoing effort.

Insights into the Microbial Degradation of Rubber and Gutta-Percha by Analysis of the Complete Genome of Nocardia nova SH22a

PubMed Central

Luo, Quan; Hiessl, Sebastian; Poehlein, Anja; Daniel, Rolf

2014-01-01

The complete genome sequence of Nocardia nova SH22a was determined in light of the remarkable ability of rubber and gutta-percha (GP) degradation of this strain. The genome consists of a circular chromosome of 8,348,532 bp with a G+C content of 67.77% and 7,583 predicted protein-encoding genes. Functions were assigned to 72.45% of the coding sequences. Among them, a large number of genes probably involved in the metabolism of xenobiotics and hardly degradable compounds, as well as genes that participate in the synthesis of polyketide- and/or nonribosomal peptide-type secondary metabolites, were detected. Based on in silico analyses and experimental studies, such as transposon mutagenesis and directed gene deletion studies, the pathways of rubber and GP degradation were proposed and the relationship between both pathways was unraveled. The genes involved include, inter alia, genes participating in cell envelope synthesis (long-chain-fatty-acid–AMP ligase and arabinofuranosyltransferase), β-oxidation (α-methylacyl-coenzyme A [α-methylacyl-CoA] racemase), propionate catabolism (acyl-CoA carboxylase), gluconeogenesis (phosphoenolpyruvate carboxykinase), and transmembrane substrate uptake (Mce [mammalian cell entry] transporter). This study not only improves our insights into the mechanism of microbial degradation of rubber and GP but also expands our knowledge of the genus Nocardia regarding metabolic diversity. PMID:24747905

49 CFR 173.334 - Organic phosphates mixed with compressed gas.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) onto a non-yielding surface, such as concrete or steel, impacting at the packaging's weakest point. (e...-yielding surface, such as concrete or steel, impacting at the weakest point. [67 FR 51651, Aug. 8, 2002, as...

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.

Where the rubber meets the road: What is needed to sustainably manage reactive nitrogen in the United States?

EPA Science Inventory

Reactive nitrogen (N) is essential for food, fuel and fiber production of a growing human population. Intensification of reactive N (defined as any N compound other than N2) release to the environment, however, has resulted in important and mounting impacts on human health and e...

A Survey of Thermal Decomposition of Solid Insulations and Its Relevance to Breakdown Mechanisms in Partial Vacuum

DTIC Science & Technology

1995-07-01

and a ductile, rubber compound ( EPDM ) utilized in applications requiring flexible insulation. These tests were typically performed in a vacuum or... EPDM ) rt7l materials, as indicated by the "x". In addition to the more common groups, data is included for a relatively new dielectric film (PBO

Rethinking the Scope of Environmental Injustice: Perceptions of Health Hazards in a Rural Native American Community Exposed to Carbon Black

ERIC Educational Resources Information Center

Shriver, Thomas E.; Webb, Gary R.

2009-01-01

We use in-depth interviews, participant observation, and document analysis to examine perceptions of environmental health and justice among Native Americans in a rural Oklahoma community. Residents live near the Continental Carbon Company, which manufactures a rubber compound know as "carbon black." Ponca tribal members believe their…

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

Smith, F. G.; Daniels, E. J.

This report summarizes an assessment conducted by Environmental Technologies Alternatives, Inc., under a subcontract to Argonne National Laboratory. The project was conducted in two phases. An assessment of alternative technologies for recycling of prompt non-tire rubber was conducted in the first phase, and an experimental program focusing on a new technology called the catalytic Regeneration Process offered the greatest opportunity for recovery of high-value recyclable rubber material. An experimental and large-scale test program was undertaken to further delineate the economic potential as an essential step leading to commercial deployment and to determine the course of continued development of the technologymore » by the private sector. The experimental program defined process-operating conditions for the technology and verified the degree of devulcanisation achievable for two rubber compounds: ethylene-propylene-nonconjugated-diene monomer (EPDM) and neoprene. To determine product acceptance, samples of devulcanized EPDM and neoprene were prepared and used in factory trials for the production of automotive moldings (EPDM) and fiber-filled belting (neoprene). The factory trials indicated that the physical properties of the products were acceptable in both cases. The appearance of molded and calendared surface finishes was acceptable, while that of extruded finishes was unsatisfactory. The fiber-filled neoprene belting application offers the greatest economic potential. Process costs were estimated at $0.34/lb for neoprene waste rubber relative to a value of $0.57/lb. The results of the experimental program led to the decision to continue development of this technology is being planned, subject to the availability of about $3 million in financing from private-sector investors. The ability to recycle non-tire rubber scrap could conserve as much as 90,000 Btu/lb, thus yielding an estimated energy savings potential of about 0.25 quad/yr.« less

Investigation of the Influence of Acoustic Oscillation Parameters on the Mechanism of Waste Rubber Products Combustion

NASA Astrophysics Data System (ADS)

Shakurov, R. F.; Sitnikov, O. R.; Galimova, A. I.; Sabitova, A. F.

2018-03-01

The article presents an analysis of the used methods of recycling of waste rubber products. The worn out tires are exposed to natural decomposition only after 50 - 100 years, and toxic organic compounds used in the manufacture constitute a danger to the environment. It contemplates a method of recycling waste rubber products in devices where pulsating combustion is realized. The dependence of the influence of acoustic pulsation parameters on the combustion mechanism of waste rubber products and on the composition of combustion products was experimentally investigated and established. For this purpose, the setup scheme based on the Rijke effect is optimized. The resonance pipe is coaxially embedded in the shaft. The known mathematical model of finding the combustion zones in the Rijke pipe, corresponding to the gas flow oscillations with the maximum amplitude, is applied to the chosen scheme. Investigations were carried out for three positions of the grate relative to the lower section of the experimental pipe, in which 1st, 2nd, 3rd modes of oscillation are formed. There are favorable conditions arise for the secondary combustion of mechanical particles entrained in the gas flow in the tube. The favorable conditions for afterburning also include the fact that through the upper section of the resonant pipe, the ambient air, caused by the features of the standing wave, is mixed into the gas stream. A comparative analysis of the change of gas concentration composition along the length of the resonance tube is carried out. It is established that the basic mode of oscillations contributes to the reduction of nitrogen oxides, in comparison with the oscillations occurring simultaneously at several harmonics, considering the main one. The results of research for the three positions of the grate in relation to the lower section of the installation are presented in tabular form, in which 1, 2, 3 modes of oscillation are formed. The analysis of experimental results confirms that the content of harmful compounds in the gas emissions below the maximum allowable norms.

High performance SMC matrix for structural applications

NASA Astrophysics Data System (ADS)

Salard, T.; Lortie, F.; Gérard, J. F.; Peyre, C.

2016-07-01

Mechanical properties of a common SMC (Sheet Molding Compound) matrix constituted of a vinylester resin and a Low-Profile Additive (LPA) were compared to those of vinylester modified with core-shell rubber (CSR) particles. Valuable properties are brought by CSR, especially high impact strength, high fracture toughness with little loss in stiffness, in spite of the presence of CSR agglomerates in blends.

Evaluation of SRM flex bearing materials and processes

NASA Technical Reports Server (NTRS)

Wood, T. E.

1980-01-01

Tensile, peel, and shear testing was performed on combinations of primers, adhesives, tycements and rubber compounds cured at various times and temperatures. The materials used in the fabrication of the solid rocket motor flex bearing as well as in other systems were evaluated. A compatibility study between adhesives and tycements was initiated. The flex bearing mold design was reviewed by our tooling experts.

Lipid droplet-associated proteins (LDAPs) are involved in the compartmentalization of lipophilic compounds in plant cells

PubMed Central

Gidda, Satinder K; Watt, Samantha C; Collins-Silva, Jillian; Kilaru, Aruna; Arondel, Vincent; Yurchenko, Olga; Horn, Patrick J; James, Christopher N; Shintani, David; Ohlrogge, John B; Chapman, Kent D; Mullen, Robert T; Dyer, John M

2013-01-01

While lipid droplets have traditionally been considered as inert sites for the storage of triacylglycerols and sterol esters, they are now recognized as dynamic and functionally diverse organelles involved in energy homeostasis, lipid signaling, and stress responses. Unlike most other organelles, lipid droplets are delineated by a half-unit membrane whose protein constituents are poorly understood, except in the specialized case of oleosins, which are associated with seed lipid droplets. Recently, we identified a new class of lipid-droplet associated proteins called LDAPs that localize specifically to the lipid droplet surface within plant cells and share extensive sequence similarity with the small rubber particle proteins (SRPPs) found in rubber-accumulating plants. Here, we provide additional evidence for a role of LDAPs in lipid accumulation in oil-rich fruit tissues, and further explore the functional relationships between LDAPs and SRPPs. In addition, we propose that the larger LDAP/SRPP protein family plays important roles in the compartmentalization of lipophilic compounds, including triacylglycerols and polyisoprenoids, into lipid droplets within plant cells. Potential roles in lipid droplet biogenesis and function of these proteins also are discussed. PMID:24305619

Influence of the silane modifiers on the surface thermodynamic characteristics and dispersion of the silica into elastomer compounds.

PubMed

Castellano, Maila; Conzatti, Lucia; Turturro, Antonio; Costa, Giovanna; Busca, Guido

2007-05-03

A good dispersion of silica into elastomers, typically used in tire tread production, is obtained by grafting of the silica with multifunctional organosilanes. In this study, the influence of the chemical structure of a triethoxysilane (TES), octadecyltriethoxysilane (ODTES), and ODTES/bistriethoxysilylpropyltetrasulfane (TESPT) mixture was investigated by inverse gas chromatography (IGC) at infinite dilution. Thermodynamic results indicate a higher polarity of the silica surface modified with TES as compared to that of the unmodified silica due to new OH groups deriving from the hydrolysis of ethoxy groups of the silane; the long hydrocarbon substituent of the ODTES lies on the surface of silica and reduces the dispersive component of the silica surface tension. A comparison with silica modified with TESPT is discussed. An accurate morphological investigation by transmission electron microscopy (TEM) and automated image analysis (AIA) was carried out on aggregates of silica dispersed into a SBR compound loaded with 35 phr (per hundred rubber) of untreated and TESPT-treated silica. Morphological descriptors such as the projected area/perimeter ratio (A/P) and roundness (P2/4piA) provided direct and quantitative indications about the distribution of the filler into the rubber matrix.

Properties of concrete with tire derived aggregate and crumb rubber as a lighthweight substitute for mineral aggregates in the concrete mix

NASA Astrophysics Data System (ADS)

Siringi, Gideon Momanyi

Scrap tires continue to be a nuisance to the environment and this research proposes one way of recycling them as a lightweight aggregate which can substitute for mineral aggregates in concrete. Aggregates derived from scrap tires are often referred to as Tire Derived Aggregate (TDA). First, the focus is how much mineral aggregate can be replaced by these waste tires and how the properties of concrete are affected with the introduction of rubber. This is being mindful of the fact that for a new material to be acceptable as an engineering material, its properties and behavior has to be well understood, the materials must perform properly and be acceptable to the regulating agencies. The role played by the quantity of TDA and Crumb Rubber replacing coarse aggregate and fine aggregate respectively as well as different treatment and additives in concrete on its properties are examined. Conventional concrete (without TDA) and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, Splitting Tensile Strength based on ASTM C496, Modulus of Rupture (flexural strength) based on ASTM C78 and Bond strength of concrete developed with reinforcing steel based on ASTM C234.Through stress-strain plots, the rubberized concrete is compared in terms of change in ductility, toughness and Elastic Modulus. Results indicate that while replacement of mineral aggregates with TDA results in reduction in compressive strength, this may be mitigated by addition of silica fume or using a smaller size of TDA to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product with lower density while utilizing recycled TDA. From the results, it is observed that 7-10% of weight of mineral aggregates can be replaced by an equal volume of TDA to produce concrete with compressive strength of up to 4000 psi (27.5 MPa). Rubberized concrete would have higher ductility and toughness with better damage tolerance but the Elastic Modulus would be reduced. After evaluation of rubberized concrete at elevated temperatures, it has been found that very high temperature would have adverse effects to the concrete like excessive spalling, pop-outs and cracking on the surface and therefore it is proposed to use this kind of concrete where temperature would not exceed 100°C (212°F) for extended periods. Observation of concrete at microscopic level showed that it consists of three phases; interfacial transition zone (ITZ), bulk hydrated cement paste and aggregate. The ITZ was seen to contain micro pores and microcracks and was considered the weakest phase in concrete therefore exercises a far greater influence on the mechanical behavior of concrete than is reflected by its size. Existence of the ITZ explains why concrete strength is lower and behaves inelastically while the aggregate and cement paste if tested separately behave elastically and have higher strength than concrete. A 3-Dimensional nonlinear Finite Element Model (FEM) for a concrete beam is proposed and developed using ABAQUS. Smeared crack model in ABAQUS is used to define material properties. The developed FEM is capable of predicting the ultimate load, deflections, Stress-deflection/strain curves and crack initiation which are all verified against the experimental tests. ABAQUS was found to be a useful tool for modeling of concrete. In conclusion, this research provides a clear understanding on the effects of using scrap tires as an aggregate in concrete. The pros and cons of TDA are explored, ways of overcoming the shortcomings suggested and a way of predicting concrete properties when using TDA provided.

Antihypertensive effect of caffeic acid and its analogs through dual renin-angiotensin-aldosterone system inhibition.

PubMed

Bhullar, Khushwant S; Lassalle-Claux, Grégoire; Touaibia, Mohamed; Rupasinghe, H P Vasantha

2014-05-05

Hypertension is a crucial risk factor for cardiovascular diseases and contributes to one third of global mortality. In addition to conventional antihypertensive drugs such as captopril, naturally occurring phytochemicals and their analogs are used for reducing the risk and occurrence of hypertension. Herein, we demonstrate the possible use of caffeic acid and its derivatives in the treatment of hypertension through multi-target modulation of renin-angiotensin-aldosterone system (RAAS). Caffeic acid along with its nineteen novel derivatives, chlorogenic acid, quercetin and captopril were all investigated for the inhibition of renin and angiotensin converting enzyme (ACE) activities and production of aldosterone. Compound 22 with CH2CH(Ph)2 moiety exhibited the strongest renin inhibition (IC50=229µM) among all compounds tested (P≤0.05). Caffeic acid was the weakest renin inhibitor (IC50=5704µM) among all the compounds assayed. Similar to renin inhibition, compound 22 (IC50=9.1µM) also exhibited about 47 times stronger ACE inhibition compared to the parent compound. Analysis of aldosterone revealed that compound 8 with n-Pr moiety was the strongest modulator of aldosterone production among all the derivatives (P≤0.05). Toxicity analysis using human fibroblasts (WI-38 cells) confirmed the non-toxic manifestations of caffeic acid and its derivatives in comparison to clinically used drug captopril. Copyright © 2014 Elsevier B.V. All rights reserved.

Supervision of Ethylene Propylene Diene M-Class (EPDM) Rubber Vulcanization and Recovery Processes Using Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy and Multivariate Analysis.

PubMed

Riba Ruiz, Jordi-Roger; Canals, Trini; Cantero, Rosa

2017-01-01

Ethylene propylene diene monomer (EPDM) rubber is widely used in a diverse type of applications, such as the automotive, industrial and construction sectors among others. Due to its appealing features, the consumption of vulcanized EPDM rubber is growing significantly. However, environmental issues are forcing the application of devulcanization processes to facilitate recovery, which has led rubber manufacturers to implement strict quality controls. Consequently, it is important to develop methods for supervising the vulcanizing and recovery processes of such products. This paper deals with the supervision process of EPDM compounds by means of Fourier transform mid-infrared (FT-IR) spectroscopy and suitable multivariate statistical methods. An expedited and nondestructive classification approach was applied to a sufficient number of EPDM samples with different applied processes, that is, with and without application of vulcanizing agents, vulcanized samples, and microwave treated samples. First the FT-IR spectra of the samples is acquired and next it is processed by applying suitable feature extraction methods, i.e., principal component analysis and canonical variate analysis to obtain the latent variables to be used for classifying test EPDM samples. Finally, the k nearest neighbor algorithm was used in the classification stage. Experimental results prove the accuracy of the proposed method and the potential of FT-IR spectroscopy in this area, since the classification accuracy can be as high as 100%.

Friction and wear study of NR/SBR blends with Si3N4Filler

NASA Astrophysics Data System (ADS)

GaneshKumar, A.; Balaganesan, G.; Sivakumar, M. S.

2018-04-01

The aim of this paper is to investigate mechanical and frictional properties of natural rubber/styrene butadiene rubber (NR/SBR) blends with and without silicon nitride (Si3N4) filler. The rubber is surface modified by silane coupling agent (Si-69) for enhancing hydrophobic property. The Si3N4of percentage 0 1, 3, 5 and 7, is incorporated into NR/SBR rubber compounds with 20% precipitated silica. The specimens with and without fillers are prepared as per standard for tensile and friction testing. Fourier transform infrared (FTIR) spectroscopy test is conducted and it is inferred that the coupling agent is covalently bonded on the surface of Si3N4 particles and an organic coating layer is formed. The co-efficient of friction and specific wear rate of NR/SBR blends are examined using an in-house built friction tester in a disc-on-plate (DOP) configuration. The specimens are tested to find coefficient of friction (COF) against steel grip antiskid plate under dry, mud, wet and oil environmental conditions. It is found that the increase in tensile strength and modulus at low percentage of Si3N4 dispersion. It is also observed that increase in sliding friction co-efficient and decrease in wear rate for 1% of Si3N4 dispersion in NR/SBR blends. The friction tested surfaces are inspected using Scanning Electron Microscope (SEM) and 3D non contact surface profiler.

Influence of acetone extract from natural rubber on the structure and interface interaction in NR/silica composites

NASA Astrophysics Data System (ADS)

Xu, Tiwen; Jia, Zhixin; Wu, Lianghui; Chen, Yongjun; Luo, Yuanfang; Jia, Demin; Peng, Zheng

2017-11-01

It is well known that the coupling reagents as the additional modifiers were often used to improve the reinforcement effect of silica filled natural rubber. Actually, the commercial raw NR is a mixture consisting of polyisoprene and non-isoprene, where the latter one might have impact on the properties of NR/silica composites as an inartificial modifier inside. Thus, investigating the effect of non-isoprene compounds on the structure and properties of NR/silica composites is a novel approach to disclose the peculiarity of NR, which is meaningful to the assessment of NR quality. In this paper, the influences of acetone extract (AE) from natural rubber on the structure and mechanical properties of NR/silica composites were studied. Then the interfacial interactions between AE and silica were also illustrated through Fourier transform infrared spectroscopy (FTIR), thermogravimetic analysis (TGA), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Results demonstrated the existence of hydrogen bond between silica and AE, also the covalent bond induced by esterification reaction between sbnd COOH and Sisbnd OH, which resulted in an increase of constrained regions around silica surface leading to the promotions on mechanical and dynamical properties of NR/silica composites significantly.

Thermomechanical properties of zirconium tungstate/hydrogenated nitrile butadiene rubber (HNBR) composites for low-temperature applications

NASA Astrophysics Data System (ADS)

Akulichev, Anton G.; Alcock, Ben; Tiwari, Avinash; Echtermeyer, Andreas T.

2016-12-01

Rubber compounds for pressure sealing application typically have inferior dimensional stability with temperature fluctuations compared with their steel counterparts. This effect may result in seal leakage failures when subjected to decreases in temperature. Composites of hydrogenated nitrile butadiene rubber (HNBR) and zirconium tungstate as a negative thermal expansion filler were prepared in order to control the thermal expansivity of the material. The amount of zirconium tungstate (ZrW2O8) was varied in the range of 0 to about 40 vol%. The coefficient of thermal expansion (CTE), bulk modulus, uniaxial extension and compression set properties were measured. The CTE of the ZrW2O8-filled HNBR decreases with the filler content and it is reduced by a factor of 2 at the highest filler concentration used. The filler effect on CTE is found to be stronger when HNBR is below the glass transition temperature. The experimental thermal expansion data of the composites are compared with the theoretical estimates and predictions given by FEA. The effect of ZrW2O8 on the mechanical characteristics and compression set of these materials is also discussed.

Hot air vulcanization of rubber profiles

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

Gerlach, J.

1995-07-01

Elastomer profiles are deployed in quantity by the automobile industry as seals and wateproofing in coachwork. The high standards demanded by the industry; improvement in weather prediction, noise reduction, restriction of tolerances, together with powerful demand for EPDM force the rubber processing industry into development, particularly of elastomers. Complex proofing systems must also be achieved with extremely complicated profile forms. All too often such profiles have an extremely large surface together with a low cross-section density. They frequently consist of two or three rubber compounds and are steel reinforced. Sometimes they are flocked and coated with a low friction finish.more » Such high-tech seals require an adjustment of the vulcanization method. The consistent trend in the nineties towards lower quantities of elastomer per sealing unit and the dielectric factor, especially with EPDM, has brought an old fashioned vulcanization method once more to the fore, a method developed over the past years to an extremely high standard, namely the hot-air method. This paper describes various vulcanization and curing methods and their relative merits and disadvantages, the Gerlach hot-air concept, the hot air installation concept, and energy saving and efficiency afforded by this technique. 4 figs.« less

Automated method for determining Instron Residual Seal Force of glass vial/rubber closure systems.

PubMed

Ludwig, J D; Nolan, P D; Davis, C W

1993-01-01

Instron Residual Seal Force (IRSF) of glass vial/rubber closure systems was determined using an Instron 4501 Materials Testing System. Computer programs were written to process raw data and calculate IRSF values. Preliminary experiments indicated both the appearance of the stress-deformation curves and precision of the derived IRSF values were dependent on the internal dimensions and top surface geometry of the cap anvil. Therefore, a series of five cap anvils varying in shape and dimensions were machined to optimize performance and precision. Vials capped with West 4416/50 PURCOAT button closures or Helvoet compound 6207 lyophilization closures were tested with each cap anvil. Cap anvils with spherical top surfaces and narrow internal dimensions produced more precise results and more uniform stress-deformation curves than cap anvils with flat top surfaces and wider internal dimensions.

[AAPH scavenging activities of 22 flavonoids and phenolic acids and 9 extracts of Chinese materia medica].

PubMed

Dai, Huiqing; Chen, Chengyu; Yang, Bin

2010-09-01

To investigate the AAPH scavenging activities of 22 flavonoids and phenolic acids and 9 extracts of Chinese materia medica. The antioxidant activities of the samples were evaluated by an oxygen radical absorbance capacity method (ORAC), at the same time, the total contents of flavonoids and phenolic the 9 herb extracts were analyzed by Folin-Ciocalteu method, and the active components were qualitatively and quantitatively analyzed by an HPLC method. It was found that the tea extract showed the strongest AAPH activity with the ORAC value of 4786.40 micromol x g(-1) whereas safflower demonstrated the weakest activity with the ORAC value of 784.04 micromol x g(-1). As for compounds, quercetin had the strongest AAPH activity with the ORAC value of 12.90 while ( - )-EGC had the weakest activity with the ORAC value of 2.47. A quantitative relationship was obtained to describe the AAPH scavenging activity of the herb extracts: Y = 1844.8 lnX-3577.5, r = 0.8675, where Y stands for the ORAC vaule, and X stands for the concentration of total phenolic acids. Flavonoids and phenolic acids are the AAPH scavenging active ingredients in the Chinese herb extracts. It's a good way to study the antioxidant activity of Chinese herb extract and its chemical composition by combing ORAC method and HPLC method.

[Using Community Resources to Re-Integrate Ex-Offenders into Society].

ERIC Educational Resources Information Center

Carlson, Norman A.

A criminal justice system cannot be stronger than its weakest link, and corrections has been the weakest component in our system for far too long. Today's challenge is that of bringing together concerned citizens, public agencies, and private agencies in an effort to create a correctional system that works. Correctional programs can accomplish…

Antennal olfactory responses of adult meadow spittlebug, Philaenus spumarius, to volatile organic compounds (VOCs)

PubMed Central

Ganassi, Sonia; Pistillo, Marco O.; Di Domenico, Carmela; De Cristofaro, Antonio; Di Palma, Antonella Marta

2017-01-01

The meadow spittlebug, Philaenus spumarius L. (Hemiptera, Aphrophoridae) is a commonly found vector of Xylella fastidiosa Wells et al. (1987) strain subspecies pauca associated with the “Olive Quick Decline Syndrome” in Italy. To contribute to the knowledge of the adult P. spumarius chemoreceptivity, electroantennographic (EAG) responses of both sexes to 50 volatile organic compounds (VOCs) including aliphatic aldehydes, alcohols, esters, and ketones, terpenoids, and aromatics were recorded. Measurable EAG responses were elicited by all compounds tested. In both sexes, octanal, 2-octanol, 2-decanone, (E)-2-hexenyl acetate, and vanillin elicited the strongest antennal amplitude within the chemical groups of aliphatic saturated aldehydes, aliphatic alcohols, aliphatic acetates and aromatics, respectively. Male and female EAG responses to sulcatol, (±)linalool, and sulcatone were higher than those to other terpenoinds. In both sexes, the weakest antennal stimulants were phenethyl alcohol and 2-pentanone. Sexual differences in the EAG amplitude were found only for four of test compounds suggesting a general similarity between males and females in antennal sensitivity. The olfactory system of both sexes proved to be sensitive to changes in stimulus concentration, carbon chain length, and compound structure. Compounds with short carbon chain length (C5—C6) elicited lower EAG amplitudes than compounds with higher carbon chain length (C9—C10) in all classes of aliphatic hydrocarbons with different functional groups. The elucidation of the sensitivity profile of P. spumarius to a variety of VOCs provides a basis for future identification of behaviorally-active compounds useful for developing semiochemical-based control strategies of this pest. PMID:29287108

Inhibition of cytochrome P450 3A by acetoxylated analogues of resveratrol in in vitro and in silico models

NASA Astrophysics Data System (ADS)

Basheer, Loai; Schultz, Keren; Kerem, Zohar

2016-08-01

Many dietary compounds, including resveratrol, are potent inhibitors of CYP3A4. Here we examined the potential to predict inhibition capacity of dietary polyphenolics using an in silico and in vitro approaches and synthetic model compounds. Mono, di, and tri-acetoxy resveratrol were synthesized, a cell line of human intestine origin and microsomes from rat liver served to determine their in vitro inhibition of CYP3A4, and compared to that of resveratrol. Docking simulation served to predict the affinity of the synthetic model compounds to the enzyme. Modelling of the enzyme’s binding site revealed three types of interaction: hydrophobic, electrostatic and H-bonding. The simulation revealed that each of the examined acetylations of resveratrol led to the loss of important interactions of all types. Tri-acetoxy resveratrol was the weakest inhibitor in vitro despite being the more lipophilic and having the highest affinity for the binding site. The simulation demonstrated exclusion of all interactions between tri-acetoxy resveratrol and the heme due to distal binding, highlighting the complexity of the CYP3A4 binding site, which may allow simultaneous accommodation of two molecules. Finally, the use of computational modelling may serve as a quick predictive tool to identify potential harmful interactions between dietary compounds and prescribed drugs.

Chemical composition and antioxidant and anti-inflammatory potential of peels and flesh from 10 different pear varieties (Pyrus spp.).

PubMed

Li, Xia; Wang, Tingting; Zhou, Bin; Gao, Wenyuan; Cao, Jingguo; Huang, Luqi

2014-01-01

This study was performed to compare the contents of total phenolics, total flavonoids, and total triterpenes between peel and flesh of ten different pear cultivars. The monomeric compounds were analyzed by HPLC, their antioxidant and anti-inflammatory activities were also measured. Peel and flesh from Yaguang, Hongpi, Qingpi and Guifei varieties contained relatively more total phenolic, total flavonoids and total triterpene, and showed stronger antioxidant and anti-inflammatory activities, while Lvbaoshi and Youran appeared to be weakest among them. All the chemical components found in the pear peel were approximately 6-20 times higher than those in the flesh of pear. For the monomeric compounds, arbutin, oleanolic acid, ursolic acid, chlorogenic acid, epicatechin, and rutin were the dominant components contained in the ten pear cultivars both in peel and in flesh. All of the analyses suggested that the peel of pear might be an excellent polyphenol and triterpenes source. Copyright © 2013 Elsevier Ltd. All rights reserved.

The role of carbon nanotubes in promoting the properties of carbon black-filled natural rubber/butadiene rubber composites

NASA Astrophysics Data System (ADS)

He, Yan; Gao, Jiangshan; Gong, Xiubin; Xu, Jin

80/20 natural rubber (NR)/butadiene rubber (BR) blends in which the carbon black (CB) was replaced partially by multi-walled carbon nanotubes (MWCNTs) according to the ratios m (CNTs): m (decreasing amount of CB) = 1: X (X was varied from 1 to 6), was prepared by blending of internal mixer and the two-roll mill at the mill opening of 0.5 mm for 10 times. SEM and TEM were used to investigate the filler networks and the good dispersion of fillers. The compounds containing 5 phr CNTs/27.5 phr CB exhibited the best abrasion resistance which was increased by 12.69% compared that without CNTs. 3D morphology images of wear surfaces and tensile fracture surfaces being similar to the layered map of the geography, which match the abrasion resistance and tensile properties, were observed by 3D measuring laser microscope. The uncured blend with 5 phr CNTs/35 phr CB showed the shortest cure time, the highest modulus and level of crosslink density. Significant improvement in mechanical properties were achieved by incorporating 5 phr CNTs and 35 phr CB, and the tear strength, 100% and 300% modulus of the vulcanizate were enhanced by 36.36%, 61.29% and 31.63% compared with the composite with 0 phr CNTs/40 phr CB, respectively. Additionally, compared with the composite without CNTs, the thermal conductivity of the composites with 5 phr CNTs/35 phr CB is increased by an average of 6.15% at three different temperatures. These considerable reinforcements resulted from the synergistic effect of CNTs and CB.

Temperature Coefficients of Electrical Conductivity and Conduction Mechanisms in Butyl Rubber-Carbon Black Composites

NASA Astrophysics Data System (ADS)

Alzamil, M. A.; Alfaramawi, K.; Abboudy, S.; Abulnasr, L.

2018-02-01

Electrical properties of butyl rubber filled with General Purpose Furnace (GPF) carbon black were studied. The carbon black concentration ( X) in the compound was X = 40, 60, 70, 80, and 100 parts by weight per hundred parts by weight of rubber (phr). The corresponding volume fractions of GPF carbon black were 0.447 ± 0.022, 0.548 ± 0.027, 0.586 ± 0.029, 0.618 ± 0.031 and 0.669 ± 0.034, respectively. The concentration dependence of conductivity ( σ ) at constant temperature showed that σ follows a percolation theory; σ ∝ ( {X - Xo } )^{γ } , where X o is the concentration at percolation threshold. The exponent γ was found as 6.6 (at room temperature 30°C). This value agrees with other experimental values obtained by many authors for different rubber-carbon black systems. Electron tunneling between the aggregates, which are dispersed in the insulator rubber, was mainly the conduction process proposed at constant temperature in the butyl-GPF carbon black composites. Temperature dependence of conductivity was investigated in the temperature range from 30°C up to 120°C. All samples exhibit negative temperature coefficients of conductivity (NTCC). The values obtained are - 0.130°C-1, - 0.019°C-1, - 0.0082°C-1, - 0.0094°C-1, and - 0.072°C-1 for carbon black concentrations of 40 phr, 60 phr, 70 phr, 80 phr, and 100 phr, respectively. The samples of concentrations 40 phr and 60 phr have also positive temperature coefficients of conductivity (PTCC) of values + 0.031 and + 0.013, respectively. Electrical conduction at different temperatures showed various mechanisms depending on the carbon black concentration and/or the interval of temperature. The hopping conduction mechanism was noticed at the lower temperature region while carrier thermal activation mechanisms were recorded at the higher temperature range.

Mechanical and thermal properties of short-coirfiber-reinforced natural rubber/polyethylene composites

NASA Astrophysics Data System (ADS)

Xu, Zh. H.; Kong, Zh. N.

2014-07-01

Natural rubber (NR) and polyethylene (PE) composites were compounded with chemically treated coir fibers by using a heated two-roll mill. Two chemical treatments of the fibers — by silane and sodium hydroxide — were carried out to improve the interfacial adhesion between them and the polyethylene matrix. The mechanical properties of the composites obtained were evaluated and compared with those made from a neat polymer and untreated fibers. The mechanical properties of the composites, such as the tensile strength, Young's modulus, and the elongation at break, were examined, and their shrinkage and flame retardant characteristics were measured. From these experiments, the effect of plasma treatment on the mechanical-physical behavior of coconut-fiberreinforced NR/PE composites was identified. In addition, their thermal characteristics were evaluated, and the results showed a slight decrease in them with increasing content of coir fibers.

Properties and potential environmental applications of carbon adsorbents from waste tire rubber

USGS Publications Warehouse

Lehmann, C.M.B.; Rameriz, D.; Rood, M.J.; Rostam-Abadi, M.

2000-01-01

The properties of tire-derived carbon adsorbents (TDCA) produced from select tire chars were compared with those derived from an Illinois coal and pistachio nut shells. Chemical analyses of the TDCA indicated that these materials contain metallic elements not present in coal-and nut shell-derived carbons. These metals, introduced during the production of tire rubber, potentially catalyze steam gasification reactions of tire char. TDCA carbons contained larger meso-and macopore volumes than their counterparts derived from coal and nut shell (on the moisture-and ash-free-basis). Adsorptive properties of the tire-derived adsorbent carbons for air separation, gas storage, and gas clean up were also evaluated and compared with those of the coal-and nut shell derived carbons as well as a commercial activated carbon. The results revealed that TDCA carbons are suitable adsorbents for removing vapor-phase mercury from combustion flue gases and hazardous organic compounds from industrial gas streams.

Performance of magnetorheological elastomer based green epoxidized natural rubber/sucrose acetate isobutyrate hybrid matrix

NASA Astrophysics Data System (ADS)

Khairi, Muntaz Hana Ahmad; Amri Mazlan, Saiful; Aziz, Siti Aishah Abdul; Ubaidillah; Tan Shilan, Salihah

2018-04-01

This study introduces a sucrose acetate isobutyrate (SAIB) as a novel additive of magnetorheological elastomers (MREs). The MREs utilized an epoxidized natural rubber (ENR) as the matrix and carbonyl iron particles (CIPs) as their filler. The CIPs were fixed at 60 wt%. The viscosity of the compound was observed using a viscometer. Meanwhile, the microstructures were observed by using field emission scanning electron microscope (FESEM). Rheological properties regarding shear storage modulus were measured by using a rheometer (MCR 302, Anton Paar). The experimental results demonstrated that the MREs-based ENR/SAIB had a decrement in their viscosity by 40% reduction. Moreover, the magnetorheological (MR) effect increased by 23% as the increment of magnetic fields. The morphological photograph showed that the CIPs embedded well within the matrix. The fabricated MREs samples were strain dependent, where all MREs samples exhibit the deteriorating trend when increasing the strain amplitude.

Tensile, swelling and morphological properties of bentonite-filled acrylonitrile butadiene rubber composites

NASA Astrophysics Data System (ADS)

Lotfi, Muhamad Nadhli Amin; Ismail, Hanafi; Othman, Nadras

2017-10-01

Tensile, swelling and morphological properties of bentonite filled acrylonitrile butadiene rubber (NBR/Bt) composites were studied. The experiments were conducted at room temperature by using two rolled mill, universal testing machine (INSTRON), and American Standard Testing Method (ASTM) D471 for compounding, tensile testing, and swelling test, respectively. Results obtained indicated that a better tensile strength, elongation at break and tensile modulus were recorded as compared to the pure NBR particularly up to 90 phr of Bt loading. However, swelling (%) exhibited the opposite trend where the liquid uptake by the composites was indirectly proportional with the increasing of Bt loading. Scanning electron microscopy (SEM) used on the tensile fractured surface of the NBR/Bt composites have shown that the fillers were well embedded in the NBR matrix, for Bt loading up to 90 phr. The agglomeration of fillers occurred for Bt loading exceeding 90 phr.

In vitro action of progestogens on sperm migration in human cervical mucus;.

PubMed

Kesserü, E; Camacho-Ortega, P; Laudahn, G; Schopflin, G

1975-01-01

The presence of progestogens in the cervical mucus suppresses and arrests sperm penetration. Using the Kremer technique, the effects of in vitro released progesterone, d-norgestrel, and cyproterone acetate were studied by inserting silicone rubber threads bearing the respective compounds into capillary tubes containing cervical mucus. Control tubes were fitted with nonmedicated silicone rubber threads. After 24 hours of incubation, the sperm migration test was carried out to evaluate penetration depth, qualitative motility, and proportion of motile forms. Progesterone produced the greatest alterations. Migration was arrested within 30 minutes, the distance reached was consistently less than 2 cm, and sperm were completely immobile at 24 hours. D-norgestrel also exhibited a distinct spermiostatic effect, but it was not as intense as that of progesterone. Cyproterone acetate was practically effective during the first 120 minutes and produced alterations only in the qualitative and proportional motility.

Optimal tyre usage for a Formula One car

NASA Astrophysics Data System (ADS)

Tremlett, A. J.; Limebeer, D. J. N.

2016-10-01

Variations in track temperature, surface conditions and layout have led tyre manufacturers to produce a range of rubber compounds for race events. Each compound has unique friction and durability characteristics. Efficient tyre management over a full race distance is a crucial component of a competitive race strategy. A minimum lap time optimal control calculation and a thermodynamic tyre wear model are used to establish optimal tyre warming and tyre usage strategies. Lap time sensitivities demonstrate that relatively small changes in control strategy can lead to significant reductions in the associated wear metrics. The illustrated methodology shows how vehicle setup parameters can be optimised for minimum tyre usage.

Production facility layout by comparing moment displacement using BLOCPLAN and ALDEP Algorithms

NASA Astrophysics Data System (ADS)

Tambunan, M.; Ginting, E.; Sari, R. M.

2018-02-01

Production floor layout settings include the organizing of machinery, materials, and all the equipments used in the production process in the available area. PT. XYZ is a company that manufactures rubber and rubber compounds for retreading tire threaded with hot and cold cooking system. In the production of PT. XYZ is divided into three interrelated parts, namely Masterbatch Department, Department Compound, and Procured Thread Line Department. PT. XYZ has a production process with material flow is irregular and the arrangement of machine is complicated and need to be redesigned. The purpose of this study is comparing movement displacement using BLOCPLAN and ALDEP algorithm in order to redesign existing layout. Redesigning the layout of the production floor is done by applying algorithms of BLOCPLAN and ALDEP. The algorithm used to find the best layout design by comparing the moment displacement and the flow pattern. Moment displacement on the floor layout of the company’s production currently amounts to 2,090,578.5 meters per year and material flow pattern is irregular. Based on the calculation, the moment displacement for the BLOCPLAN is 1,551,344.82 meter per year and ALDEP is 1,600,179 meter per year. Flow Material resulted is in the form of straight the line.

Impacts of the East Asian Monsoon on springtime dust concentrations over China: IMPACTS OF MONSOON ON DUST

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

Lou, Sijia; Russell, Lynn M.; Yang, Yang

We use 150 year preindustrial simulations of the Community Earth System Model to quantify the impacts of the East Asian Monsoon strength on interannual variations of springtime dust concentrations over China. The simulated interannual variations in March-April-May (MAM) dust column concentrations range between 20–40% and 10–60% over eastern and western China, respectively. The dust concentrations over eastern China correlate negatively with the East Asian Monsoon (EAM) index, which represents the strength of monsoon, with a regionally averaged correlation coefficient of 0.64. Relative to the strongest EAM years, MAMdust concentrations in the weakest EAM years are higher over China, with regionalmore » relative differences of 55.6%, 29.6%, and 13.9% in the run with emissions calculated interactively and of 33.8%, 10.3%, and 8.2% over eastern, central, and western China, respectively, in the run with prescribed emissions. Both interactive run and prescribed emission run show the similar pattern of climate change between the weakest and strongest EAM years. Strong anomalous northwesterly and westerly winds over the Gobi and Taklamakan deserts during the weakest EAM years result in larger transport fluxes, and thereby increase the dust concentrations over China. These differences in dust concentrations between the weakest and strongest EAM years (weakest-strongest) lead to the change in the net radiative forcing by up to 8 and 3Wm2 at the surface, compared to 2.4 and +1.2Wm2 at the top of the atmosphere over eastern and western China, respectively.« less

Evaluation of the Effect of Silicone Contamination on Various Bond Systems and the Feasibility of Removing the Contamination

NASA Technical Reports Server (NTRS)

Stanley, Stephanie D.

2008-01-01

Silicone is a contaminant that can cause catastrophic failure of a bond system depending on the materials and processes used to fabricate the bond system, Unfortunately, more and more materials are fabricated using silicone. The purpose of this testing was to evaluate which bond systems are sensitive to silicone contamination and whether or not a cleaning process could be utilized to remove the silicone to bring the bond system performance back to baseline. Due to the extensive nature of the testing attempts will be made to generalize the understanding within classes of substrates, bond systems, and surface preparation and cleaning methods. This study was done by contaminating various meta! (steel, inconel, and aluminum), phenolic (carbon cloth phenolic and glass cloth phenolic), and rubber (natural rubber, asbestos-silicone dioxide filled natural butyldiene rubber, silica-filled ethylene propylenediene monomer, and carbon-filled ethylene propylenediene monomer) substrates which were then bonded using various adhesives and coatings (epoxy-based adhesives, paints, ablative compounds, and Chemlok adhesives) to determine the effect silicone contamination has on a given bond system's performance. The test configurations depended on the bond system being evaluated. The study also evaluated the feasibility of removing the silicone contamination by cleaning the contaminated substrate prior to bonding. The cleaning processes also varied depending on bond system.

Morphology Formation in PC/ABS Blends during Thermal Processing and the Effect of the Viscosity Ratio of Blend Partners

PubMed Central

Bärwinkel, Stefanie; Seidel, Andreas; Hobeika, Sven; Hufen, Ralf; Mörl, Michaela; Altstädt, Volker

2016-01-01

Morphology formation during compounding, as well as injection molding of blends containing 60 wt % polycarbonate (PC) and 40 wt % polybutadiene rubber-modified styrene-acrylonitrile copolymers (ABS), has been investigated by transmission electron microscopy (TEM). Profiles of the blend morphology have been recorded in injection-molded specimens and significant morphology gradients observed between their skin and core. A <10 µm thick surface layer with strongly dispersed and elongated nano-scale (streak-like) styrene acrylonitrile (SAN) phases and well-dispersed, isolated SAN-grafted polybutadiene rubber particles is followed by a 50–150 µm thick skin layer in which polymer morphology is characterized by lamellar SAN/ABS phases. Thickness of these lamellae increases with the distance from the specimen’s surface. In the core of the specimens the SAN-grafted polybutadiene rubber particles are exclusively present within the SAN phases, which exhibit a much coarser and less oriented, dispersed morphology compared to the skin. The effects of the viscosity of the SAN in the PC/ABS blends on phase morphologies and correlations with fracture mechanics in tensile and impact tests were investigated, including scanning electron microscopy (SEM) assessment of the fracture surfaces. A model explaining the mechanisms of morphology formation during injection molding of PC/ABS blends is discussed. PMID:28773780

Synergistic effect of nano calcium carbonate (NCC)/carbon black (CB) on the cure characteristics and physico-mechanical properties of NR/SBR blends

NASA Astrophysics Data System (ADS)

Mamauod, Siti Nur Liyana; Romli, Ahmad Zafir; Rizuan, Mohd Ismail Rifdi

2017-09-01

This research was carried out as to develop hybrid filler reinforced into the blend of natural rubber (NR) and styrene butadiene rubber (SBR). The NR/SBR blend was reinforced using carbon black (CB) and nano calcium carbonate (NCC). The NCC content varied from 2-10 phr which was incorporated into the NR/SBR blend filled with fixed 50 phr of CB. The main aim of this project was to study the synergistic effect of NCC and CB reinforced NR/SBR blends towards the curing characteristics using cure rheometer, the viscosity of uncured NR/SBR compounds, physical and mechanical property blends. From the results obtained, the optimum ratio of blending was identified at 4 phr of NCC loading. Tensile strength, elongation at break, modulus and hardness increased progressively with increasing the NCC loading from 0 phr up to a maximum value at 4 phr. This increment occurs due to consolidation of the network structure of the polymer chains with the increasing NCC content. Up to the optimum amount of NCC, the tendency for NCC particles to form aggregate was very high and hence reduces the properties of rubber blends. It proved that NCC acts as a co-reinforcing agent for CB to improve the performance in the NR/SBR blends.

The activity of thymidine phosphorylase obtained from human uterine leiomyomas and studied in the presence of pyrimidine derivatives.

PubMed

Miszczak-Zaborska, E; Woźniak, K

1997-01-01

Partially purified samples of thymidine phosphorylase were obtained from four preparations of human uterine leiomyomas and uteri using the method of Yoshimura et al. (1990), Biochim. Biophys. Acta 1034, 107-113. Among the studied twelve pyrimidine derivatives, 5-bromouracil, 5-nitrouracil, 5-fluorouracil, 6-aminouracil, 4, 6-dihydroxy-5-nitropyrimidine are competitive inhibitors, while allyloxymethylthymine is an uncompetitive inhibitor of thymidine phosphorylase activity, 6-benzyl-2-thiouracil inhibits the activity of the enzyme in a mixed way. The most potent inhibitor of the thymidine phosphorylase activity is 5-bromouracil and uracil the weakest one. Stronger inhibition of these compounds on the activity of thymidine phosphorylase was found in uterine leiomyomas than in uteri.

Influence of Rubber Size on Properties of Crumb Rubber Mortars

PubMed Central

Yu, Yong; Zhu, Han

2016-01-01

Studies on the properties and applications of rubber cement-based materials are well documented. The sizes of rubbers used in these materials varied. However, information about the effects of rubber size on the properties of rubber cement-based materials, especially pore structure, mechanical strengths, and drying shrinkage properties, remains limited. Three groups of rubber with major particle sizes of 2–4 mm, 1–3 mm, and 0–2 mm were selected in this study. This paper presents experimental studies on the effects of rubber size on the consistency, fresh density, pore structure, mechanical properties, and drying shrinkage properties of crumb rubber mortars (CRMs). Results demonstrated that the consistency and fresh density of CRMs decreased with the rubber size. As to the pore structure, the total pore volume increased with the decrease of the rubber size. By contrast, the influence of the rubber size on the mesopore (<50 nm) volume is not as significant as that of the rubber content. The mechanical properties of CRMs decreased with the rubber size. Low rubber stiffness and large pore volumes, especially those of small sized rubbers, contribute to the reduction of CRMs strength. The drying shrinkage of CRM increases as the rubber size decreases. The influences of rubber size on capillary tension are not significant. Thus, the shrinkage increases with the decrease of rubber size mainly because of its function in the deformation modulus reduction of CRMs. PMID:28773649

Down-Regulation of Small Rubber Particle Protein Expression Affects Integrity of Rubber Particles and Rubber Content in Taraxacum brevicorniculatum

PubMed Central

Hillebrand, Andrea; Post, Janina J.; Wurbs, David; Wahler, Daniela; Lenders, Malte; Krzyzanek, Vladislav; Prüfer, Dirk; Gronover, Christian Schulze

2012-01-01

The biosynthesis of rubber is thought to take place on the surface of rubber particles in laticifers, highly specialized cells that are present in more than 40 plant families. The small rubber particle protein (SRPP) has been supposed to be involved in rubber biosynthesis, and recently five SRPPs (TbSRPP1–5) were identified in the rubber-producing dandelion species Taraxacum brevicorniculatum. Here, we demonstrate by immunogold labeling that TbSRPPs are localized to rubber particles, and that rubber particles mainly consist of TbSRPP3, 4 and 5 as shown by high-resolution two-dimensional gel electrophoresis and mass spectrometric analysis. We also carried out an RNA-interference approach in transgenic plants to address the function of TbSRPPs in rubber biosynthesis as well as rubber particle morphology and stability. TbSRPP-RNAi transgenic T. brevicorniculatum plants showed a 40–50% reduction in the dry rubber content, but neither the rubber weight average molecular mass nor the polydispersity of the rubber were affected. Although no phenotypical differences to wild-type particles could be observed in vivo, rubber particles from the TbSRPP-RNAi transgenic lines were less stable and tend to rapidly aggregate in expelling latex after wounding of laticifers. Our results prove that TbSRPPs are very crucial for rubber production in T. brevicorniculatum, probably by contributing to a most favourable and stable rubber particle architecture for efficient rubber biosynthesis and eventually storage. PMID:22911861

Extraction tools for identification of chemical contaminants in estuarine and coastal waters to determine toxic pressure on primary producers.

PubMed

Booij, Petra; Sjollema, Sascha B; Leonards, Pim E G; de Voogt, Pim; Stroomberg, Gerard J; Vethaak, A Dick; Lamoree, Marja H

2013-09-01

The extent to which chemical stressors affect primary producers in estuarine and coastal waters is largely unknown. However, given the large number of legacy pollutants and chemicals of emerging concern present in the environment, this is an important and relevant issue that requires further study. The purpose of our study was to extract and identify compounds which are inhibitors of photosystem II activity in microalgae from estuarine and coastal waters. Field sampling was conducted in the Western Scheldt estuary (Hansweert, The Netherlands). We compared four different commonly used extraction methods: passive sampling with silicone rubber sheets, polar organic integrative samplers (POCIS) and spot water sampling using two different solid phase extraction (SPE) cartridges. Toxic effects of extracts prepared from spot water samples and passive samplers were determined in the Pulse Amplitude Modulation (PAM) fluorometry bioassay. With target chemical analysis using LC-MS and GC-MS, a set of PAHs, PCBs and pesticides was determined in field samples. These compound classes are listed as priority substances for the marine environment by the OSPAR convention. In addition, recovery experiments with both SPE cartridges were performed to evaluate the extraction suitability of these methods. Passive sampling using silicone rubber sheets and POCIS can be applied to determine compounds with different structures and polarities for further identification and determination of toxic pressure on primary producers. The added value of SPE lies in its suitability for quantitative analysis; calibration of passive samplers still needs further investigation for quantification of field concentrations of contaminants. Copyright © 2013 Elsevier Ltd. All rights reserved.

Reusable Material for Drop Tower

DTIC Science & Technology

2011-08-01

R3 Buna-N Rubber ............................................................................................... 32 B-3. R5 EPDM Rubber ...Butyl Rubber . Figure B-2. R3 Buna-N Rubber . Figure B-3. R5 EPDM Rubber . Figure B-4. R6 Gel Rubber . UNCLASSIFIED 33...11 Current Drop Tower Material & Setup .......................................................... 11 Bowling Ball Rubber Material Sample Test

In-depth proteome analysis of the rubber particle of Hevea brasiliensis (para rubber tree).

PubMed

Dai, Longjun; Kang, Guijuan; Li, Yu; Nie, Zhiyi; Duan, Cuifang; Zeng, Rizhong

2013-05-01

The rubber particle is a special organelle in which natural rubber is synthesised and stored in the laticifers of Hevea brasiliensis. To better understand the biological functions of rubber particles and to identify the candidate rubber biosynthesis-related proteins, a comprehensive proteome analysis was performed on H. brasiliensis rubber particles using shotgun tandem mass spectrometry profiling approaches-resulting in a thorough report on the rubber particle proteins. A total of 186 rubber particle proteins were identified, with a range in relative molecular mass of 3.9-194.2 kDa and in isoelectric point values of 4.0-11.2. The rubber particle proteins were analysed for gene ontology and could be categorised into eight major groups according to their functions: including rubber biosynthesis, stress- or defence-related responses, protein processing and folding, signal transduction and cellular transport. In addition to well-known rubber biosynthesis-related proteins such as rubber elongation factor (REF), small rubber particle protein (SRPP) and cis-prenyl transferase (CPT), many proteins were firstly identified to be on the rubber particles, including cyclophilin, phospholipase D, cytochrome P450, small GTP-binding protein, clathrin, eukaryotic translation initiation factor, annexin, ABC transporter, translationally controlled tumour protein, ubiquitin-conjugating enzymes, and several homologues of REF, SRPP and CPT. A procedure of multiple reaction monitoring was established for further protein validation. This comprehensive proteome data of rubber particles would facilitate investigation into molecular mechanisms of biogenesis, self-homeostasis and rubber biosynthesis of the rubber particle, and might serve as valuable biomarkers in molecular breeding studies of H. brasiliensis and other alternative rubber-producing species.

Degradation of blending vulcanized natural rubber and nitril rubber (NR/NBR) by dimethyl ether through variation of elastomer ratio

NASA Astrophysics Data System (ADS)

Saputra, A. H.; Juneva, S.; Sari, T. I.; Cifriadi, A.

2018-04-01

Dimethyl ether can cause degradation of the rubber material seal in some applications. In order to use of natural rubber in industry, research about a blending of natural rubber (NR) and nitrile rubber (NBR) to produce rubber to meet the standard seal material application were conducted. This study will observe the degradation mechanisms that occur in the blending natural rubber and nitrile rubber (NR/NBR) by dimethyl ether. Nitrile rubber types used in this study is medium quality nitrile rubber with 33% of acrylonitrile content (NBR33). The observed parameters are percent change in mass, mechanical properties and surface morphology. This study is limited to see the effect of variation vulcanized blending ratio (NR/NBR33) against to swelling. The increase of nitrile rubber (NBR33) ratio of blending rubber vulcanized can reduce the tensile strength and elongation. The best elastomer variation was obtained after comparing with the standard feasibility material of seal is rubber vulcanized blending (NR/NBR33) with ratio 40:60 NR: NBR.

Handling and Use of Fluorine and Fluorine - Oxygen Mixtures in Rocket Systems,

DTIC Science & Technology

1967-01-01

with nitroso rubber, which could normally be expected to burn when exposed to the flow of liquid fluorine. The materials tested included (1) Nitroso...the system free of contamination. Most common metals of construction are compatible for use in a fluorine environment. Metals can burn with fluorine...conditions of contact), fluorinated compounds in their highest state of oxidation, and a few fluorinated polymers. Even these polymers may burn in fluorine

Contact dermatitis in children.

PubMed

Rademaker, M; Forsyth, A

1989-02-01

125 children under the age of 12 years were patch tested over a period of 7 years. 60 (48%) of the children had 1 or more positive (+ve) reactions, of which 92% (55/60) were considered relevant. The most common allergens were metals (35 + ves), fragrances (24 + ves) and rubber compounds (11 + ves). 40 of the children were also tested for contact urticaria against food additives and fragrances, of whom 20 were positive (benzoic acid 14, cinnamaldehyde 12).

Rubber industry

NASA Astrophysics Data System (ADS)

Staszak, Maciej

2018-03-01

Following chapter presents short introductory description of rubber and rubber industry. The main problem of rubber industry is the way of the usage of spent tires. Furthermore very important group of problems arise considering the metal and nonmetal additives which are significant component of the vulcanized rubber. The key attention is dedicated to typical ways of rubber usage in utilization and recovery of metals from spent rubber materials concentrating specifically on used tires processing. The method of recovery of rare metals from rubber tires was described. The rubber debris finds widest use in the field of waste metal solutions processing. The environmental pollution caused by metals poses serious threat to humans. Several applications of the use of waste rubber debris to remove metals from environmental waters were described. Moreover, the agriculture usage of waste tire rubber debris is described, presenting systems where the rubber material can be useful as a soil replacement.

The increased incidence of pure red cell aplasia with an Eprex formulation in uncoated rubber stopper syringes.

PubMed

Boven, Katia; Stryker, Scott; Knight, John; Thomas, Adrian; van Regenmortel, Marc; Kemeny, David M; Power, David; Rossert, Jerome; Casadevall, Nicole

2005-06-01

The incidence of pure red cell aplasia (PRCA) in chronic kidney disease patients treated with epoetins increased substantially in 1998, was shown to be antibody mediated, and was associated predominantly with subcutaneous administration of Eprex. A technical investigation identified organic compounds leached from uncoated rubber stoppers in prefilled syringes containing polysorbate 80 as the most probable cause of the increased immunogenicity. This study investigated whether the incidence of PRCA was higher for exposure to the product form containing leachates than for leachate-free product forms. Antibody-mediated PRCA cases were classified according to indication, product form, and route of administration. Exposure estimates were obtained by country, indication, route of administration, and product form. For 2001 to 2003, the PRCA incidence rate for patients with subcutaneous exposure to Eprex in prefilled syringes with polysorbate 80 and uncoated rubber stoppers (leachates present) was 4.61/10,000 patient years (95% CI 3.88-5.43) versus 0.26/10,000 patient years (95% CI 0.007-1.44) for syringes with coated stoppers (leachates absent). The rate difference was 4.35/10,000 patient years (95% CI 3.44-5.26; P < 0.0001); the rate ratio was 17 (95% CI 3.14-707). A substantial rate difference remained in sensitivity analyses that adjusted for exposure to multiple product forms. The epidemiologic data, together with the chemical and immunologic data, support the hypothesis that leachates from uncoated rubber syringe stoppers caused the increased incidence of PRCA associated with Eprex. Currently, all Eprex prefilled syringes contain fluoro-resin coated stoppers, which has contributed to decreased incidence of PRCA with continued surveillance.

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. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

Reactive, spectroscopic and antimicrobial assessments of 5-[(4-methylphenyl) acetamido]-2-(4-tert-butylphenyl)benzoxazole: Combined experimental and computational study

NASA Astrophysics Data System (ADS)

Mary, Y. Sheena; Alzoman, Nourah Z.; Menon, Vidya V.; Al-Abdullah, Ebtehal S.; El-Emam, Ali A.; Panicker, C. Yohannan; Temiz-Arpaci, Ozlem; Armaković, Stevan; Armaković, Sanja J.; Van Alsenoy, C.

2017-01-01

The synthesis, FT-IR, FT-Raman and NMR spectral analysis of an antimicrobial active benzoxazole derivative, 5-[(4-methylphenyl)acetamido]-2-(4-tert-butylphenyl) benzoxazole (MPATB) is reported. The localization of HOMO, LUMO plots in the title compound over the title molecule shows the charge transfer in the molecular system through the conjugated paths.The electrophilic and nucleophilic sites are revealed from the molecular electrostatic potential map. The first hyperpolarizability of the title compound is greater than that of the standard nonlinear optical material urea and the title compound and its derivatives are good objects for further research in nonlinear optical analysis. Molecule sites prone to electrophilic attacks have been detected by calculation of average local ionization energies, while calculations of Fukui functions have provided additional information about the local reactivity properties. Bond dissociation energies have been calculated in order to investigate autoxidation possibilities of the title molecule, as well as to determine the weakest bonds and therefore the sites where process of degradation could start. Reactive properties with water have been investigated by molecular dynamics simulations and calculations of radial distribution functions. The compound possessed broad spectrum activity against all of the tested Gram-positive and Gram-negative bacteria and yeasts, their minimum inhibitory concentrations ranging between 8 and 128 μg/ml. The compound exhibited significant antifungal activity (64 μg/ml) against Candida krusei, at same potency with the compared standard drugs fluconazole. The docked title compound forms a stable complex with thymidylate synthase and got a binding affinity value of -8.5 kcal/mol and the title compound can be a lead compound for developing new anti-cancerous drug.

Generation of Hydrogen and Methane during Experimental Low-Temperature Reaction of Ultramafic Rocks with Water

NASA Astrophysics Data System (ADS)

McCollom, Thomas M.; Donaldson, Christopher

2016-06-01

Serpentinization of ultramafic rocks is widely recognized as a source of molecular hydrogen (H2) and methane (CH4) to support microbial activity, but the extent and rates of formation of these compounds in low-temperature, near-surface environments are poorly understood. Laboratory experiments were conducted to examine the production of H2 and CH4 during low-temperature reaction of water with ultramafic rocks and minerals. Experiments were performed by heating olivine or harzburgite with aqueous solutions at 90°C for up to 213 days in glass bottles sealed with butyl rubber stoppers. Although H2 and CH4 increased steadily throughout the experiments, the levels were very similar to those found in mineral-free controls, indicating that the rubber stoppers were the predominant source of these compounds. Levels of H2 above background were observed only during the first few days of reaction of harzburgite when CO2 was added to the headspace, with no detectable production of H2 or CH4 above background during further heating of the harzburgite or in experiments with other mineral reactants. Consequently, our results indicate that production of H2 and CH4 during low-temperature alteration of ultramafic rocks may be much more limited than some recent experimental studies have suggested. We also found no evidence to support a recent report suggesting that spinels in ultramafic rocks may stimulate H2 production. While secondary silicates were observed to precipitate during the experiments, formation of these deposits was dominated by Si released by dissolution of the glass bottles, and reaction of the primary silicate minerals appeared to be very limited. While use of glass bottles and rubber stoppers has become commonplace in experiments intended to study processes that occur during serpentinization of ultramafic rocks at low temperatures, the high levels of H2, CH4, and SiO2 released during heating indicate that these reactor materials are unsuitable for this purpose.

The influence of preservation method and time on the delta13C value of dissolved inorganic carbon in water samples.

PubMed

Taipale, Sami J; Sonninen, Eloni

2009-08-30

The precise delta(13)C value of dissolved inorganic carbon (DIC) is important for various types of ecological studies. Without a preservation agent, microbial degradation of organic compounds continues in water samples and the delta(13)C value of DIC will become more depleted with time. HgCl(2) or acidification is often used to prevent microbial activity in water samples collected for carbon isotope ratio analyses of DIC. Mercury compounds are toxic and result in waste disposal problems. Other inhibiting agents or preservation methods are therefore needed. Two possible solutions are to use copper sulphate (CuSO(4)) as a preservative agent or to acidify water samples with phosphoric acid (H(3)PO(4)) within 12 mL measurement Exetainers (septum-capped vials). We prepared a set of lake water samples in three types of vials: glass vials with silicone/PTFE septa, high-density polyethylene vials (HD-PE, scintillation vials) and Exetainers (12 mL) with butyl rubber septa. Samples in glass and PE vials were preserved with and without CuSO(4), whereas lake water was injected into the Exetainer and acidified with H(3)PO(4). Isotope ratios were measured in two laboratories over 6 months. The delta(13)C values of DIC systematically increased with storage time for samples preserved in glass and PE vials with and without CuSO(4). A strong correlation between a decrease of CO(2) concentration and an increase in DIC delta(13)C values was found. The delta(13)C values and DIC concentrations were stable for 6 months in acidified samples stored in Exetainers with butyl rubber septa. Therefore, we conclude that the best method for up to 6 months of storage is to inject samples in the field into butyl rubber septum capped Exetainers containing H(3)PO(4), thereby avoiding the use of preservatives. 2009 John Wiley & Sons, Ltd.

Poly (ricinoleic acid) based novel thermosetting elastomer.

PubMed

Ebata, Hiroki; Yasuda, Mayumi; Toshima, Kazunobu; Matsumura, Shuichi

2008-01-01

A novel bio-based thermosetting elastomer was prepared by the lipase-catalyzed polymerization of methyl ricinoleate with subsequent vulcanization. Some mechanical properties of the cured carbon black-filled polyricinoleate compounds were evaluated as a thermosetting elastomer. It was found that the carbon black-filled polyricinoleate compounds were readily cured by sulfur curatives to produce a thermosetting elastomer that formed a rubber-like sheet with a smooth and non-sticky surface. The curing behaviors and mechanical properties were dependent on both the molecular weight of the polyricinoleate and the amount of the sulfur curatives. Cured compounds consisting of polyricinoleate with a molecular weight of 100,800 showed good mechanical properties, such as a hardness of 48 A based on the durometer A measurements, a tensile strength at break of 6.91 MPa and an elongation at break of 350%.

Application of Weakest Link Probabilistic Framework for Fatigue Notch Factor to Aero Engine Materials

DTIC Science & Technology

2014-08-25

11 distributed cyclic microplasticity . Recent approaches have been developed to incorporate these finite process zone effects at notches [25, 26...the distribution of microvoids [50] or microplasticity [51]. According to the hypotheses on which the weakest link theory is based, given a structure...high cycle fatigue regime, where scatter of heterogeneous microplasticity in the fatigue specimen is a common occurrence. The probability of success

Managing Your Team's Weakest Link.

PubMed

Hills, Laura

2015-01-01

Do you have a poor-performing employee on your medical practice team? If so, you're not alone. Unfortunately, this is a problem that many medical practice managers face. This article describes the best strategies for managing your team's weakest link. It explores common yet very difficult circumstances that cause low employee performance and that test the patience, heart, and skills of a practice manager. It guides readers through a process of self-discovery to determine whether their negative biases or grudges may be causing employees to perform poorly. It suggests several possible other reasons for weak employee performance, including problems with the job, practice, leadership, communication, and fit between the employee and the job. This article also suggests the best strategy for communicating concerns about performance to the weakest-link employee. It offers guidance to practice managers about protecting their time and energy when handling a poor performer. It provides a simple formula for calculating the cost of a low-performing employee, 10 possible personal reasons for the employee's poor work performance, specific questions to ask to uncover the reasons for poor performance, and an eight-rule strategy for confronting poor performance effectively. Finally, this article offers practice managers a practical strategy for handling resistance from their weakest link, illustrated with a sample dialogue.

Identification of natural rubber and characterization of rubber biosynthetic activity in fig tree.

PubMed

Kang, H; Kang, M Y; Han, K H

2000-07-01

Natural rubber was extracted from the fig tree (Ficus carica) cultivated in Korea as part of a survey of rubber producing plants. Fourier transform infrared and (13)C nuclear magnetic resonance analysis of samples prepared by successive extraction with acetone and benzene confirmed that the benzene-soluble residues are natural rubber, cis-1,4-polyisoprene. The rubber content in the latex of fig tree was about 4%, whereas the rubber content in the bark, leaf, and fruit was 0.3%, 0.1%, and 0.1%, respectively. Gel-permeation chromatography revealed that the molecular size of the natural rubber from fig tree is about 190 kD. Similar to rubber tree (Hevea brasiliensis) and guayule (Parthenium argentatum Gray), rubber biosynthesis in fig tree is tightly associated with rubber particles. The rubber transferase in rubber particles exhibited a higher affinity for farnesyl pyrophosphate than for isopentenyl pyrophosphate, with apparent K(m) values of 2.8 and 228 microM, respectively. Examination of latex serum from fig tree by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed major proteins of 25 and 48 kD in size, and several proteins with molecular mass below 20 and above 100 kD. Partial N-terminal amino acid sequencing and immunochemical analyses revealed that the 25- and 48-kD proteins were novel and not related to any other suggested rubber transferases. The effect of EDTA and Mg(2+) ion on in vitro rubber biosynthesis in fig tree and rubber tree suggested that divalent metal ion present in the latex serum is an important factor in determining the different rubber biosynthetic activities in fig tree and rubber tree.

Identification of Natural Rubber and Characterization of Rubber Biosynthetic Activity in Fig Tree1

PubMed Central

Kang, Hunseung; Kang, Min Young; Han, Kyung-Hwan

2000-01-01

Natural rubber was extracted from the fig tree (Ficus carica) cultivated in Korea as part of a survey of rubber producing plants. Fourier transform infrared and 13C nuclear magnetic resonance analysis of samples prepared by successive extraction with acetone and benzene confirmed that the benzene-soluble residues are natural rubber, cis-1,4-polyisoprene. The rubber content in the latex of fig tree was about 4%, whereas the rubber content in the bark, leaf, and fruit was 0.3%, 0.1%, and 0.1%, respectively. Gel-permeation chromatography revealed that the molecular size of the natural rubber from fig tree is about 190 kD. Similar to rubber tree (Hevea brasiliensis) and guayule (Parthenium argentatum Gray), rubber biosynthesis in fig tree is tightly associated with rubber particles. The rubber transferase in rubber particles exhibited a higher affinity for farnesyl pyrophosphate than for isopentenyl pyrophosphate, with apparent Km values of 2.8 and 228 μm, respectively. Examination of latex serum from fig tree by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed major proteins of 25 and 48 kD in size, and several proteins with molecular mass below 20 and above 100 kD. Partial N-terminal amino acid sequencing and immunochemical analyses revealed that the 25- and 48-kD proteins were novel and not related to any other suggested rubber transferases. The effect of EDTA and Mg2+ ion on in vitro rubber biosynthesis in fig tree and rubber tree suggested that divalent metal ion present in the latex serum is an important factor in determining the different rubber biosynthetic activities in fig tree and rubber tree. PMID:10889262

Comparative studies on the mechanical properties of natural rubber and natural rubber filled with multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Ismail, R.; Ibrahim, A.; Rusop, M.; Adnan, A.

2018-05-01

The present article compares the mechanical properties of natural rubber (NR) and carbon nanotubes (CNTs) filled natural rubber composites. Four types of nanocomposite specimens are fabricated with different MWCNT loadings: 0 wt% (pure natural rubber), 1 wt%, 3 wt%, and 5 wt%. The specimens are tested for their mechanical properties. It is observed that the tensile strength, hardness and elongation break of CNTs filled rubber composites are remarkably higher than that of raw rubber indicating the inherent reinforcing potential of CNTs. Percentage of the elongation at break of rubber CNTs composites is lower than that of raw rubber.

Mechanical Performance Test of Rubber-Powder Modified Concrete

NASA Astrophysics Data System (ADS)

Zhang, Yan Cong; Gao, Ling Ling

2018-06-01

A number of rubber cement concrete specimens that rubber powder dosage different were obtained using same cement, water and fine aggregates, by adjusting the dosage of rubber powder. Then it was used to research the influence of rubber powder dosage on performance of cement concrete by measuring its liquidity, strength and toughness. The results show that: when water-cement ratio was equal and rubber powder replacing the same volume sand, the fluidity of cement concrete almost linear increased with rubber powder dosage increasing. With dosage of rubber powder increasing, compressive strength and flexural strength reduced, but toughness linear growth trend when dosage of rubber powder less 30%.

Inhibition of cytochrome P450 3A by acetoxylated analogues of resveratrol in in vitro and in silico models

PubMed Central

Basheer, Loai; Schultz, Keren; Kerem, Zohar

2016-01-01

Many dietary compounds, including resveratrol, are potent inhibitors of CYP3A4. Here we examined the potential to predict inhibition capacity of dietary polyphenolics using an in silico and in vitro approaches and synthetic model compounds. Mono, di, and tri-acetoxy resveratrol were synthesized, a cell line of human intestine origin and microsomes from rat liver served to determine their in vitro inhibition of CYP3A4, and compared to that of resveratrol. Docking simulation served to predict the affinity of the synthetic model compounds to the enzyme. Modelling of the enzyme’s binding site revealed three types of interaction: hydrophobic, electrostatic and H-bonding. The simulation revealed that each of the examined acetylations of resveratrol led to the loss of important interactions of all types. Tri-acetoxy resveratrol was the weakest inhibitor in vitro despite being the more lipophilic and having the highest affinity for the binding site. The simulation demonstrated exclusion of all interactions between tri-acetoxy resveratrol and the heme due to distal binding, highlighting the complexity of the CYP3A4 binding site, which may allow simultaneous accommodation of two molecules. Finally, the use of computational modelling may serve as a quick predictive tool to identify potential harmful interactions between dietary compounds and prescribed drugs. PMID:27530542

40 CFR 428.20 - Applicability; description of the emulsion crumb rubber subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... emulsion crumb rubber subcategory. 428.20 Section 428.20 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Emulsion Crumb Rubber Subcategory § 428.20 Applicability; description of the emulsion crumb rubber... manufacture of emulsion crumb rubber, other than acrylonitrilebutadiene rubber. [40 FR 18173, Apr. 25, 1975] ...

40 CFR 428.20 - Applicability; description of the emulsion crumb rubber subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... emulsion crumb rubber subcategory. 428.20 Section 428.20 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Emulsion Crumb Rubber Subcategory § 428.20 Applicability; description of the emulsion crumb rubber... manufacture of emulsion crumb rubber, other than acrylonitrilebutadiene rubber. [40 FR 18173, Apr. 25, 1975] ...

40 CFR 428.20 - Applicability; description of the emulsion crumb rubber subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... emulsion crumb rubber subcategory. 428.20 Section 428.20 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Emulsion Crumb Rubber Subcategory § 428.20 Applicability; description of the emulsion crumb rubber... manufacture of emulsion crumb rubber, other than acrylonitrilebutadiene rubber. [40 FR 18173, Apr. 25, 1975] ...

Strength and microstructure characteristics of the recycled rubber tire-sand mixtures as lightweight backfill.

PubMed

Zhang, Tao; Cai, Guojun; Duan, Weihong

2018-02-01

The disposal of scrap rubber tires has induced critical environmental issue worldwide due to the rapid increase in the number of vehicles. Recycled scrap tires as a construction material in civil engineering have significant environmental benefits from a waste management perspective. A systematic study that deals with strength and microstructure characteristics of the rubber-sand mixtures is initiated, and mechanical response of the mixtures is discussed in this investigation. Experiments were conducted to evaluate the effects of rubber fraction on the basic properties including mass density (ρ), stress-strain characteristics, shear strength, and unconfined compression strength (q u ) of the rubber-sand mixtures. Additionally, scanning electron microscopy (SEM) was carried out to reveal the microstructure characteristics of the mixtures with various rubber fractions. A discussion on the micromechanics of the mixtures also was conducted. This study demonstrates that the ρ, friction angle, and q u decrease linearly with an increase in rubber fraction, whereas shear strain at peak increases. The stress-strain characteristics of the rubber-sand mixtures shift from brittle to ductile as the rubber fraction increase. These changes are attributed to remarkably lower stiffness and higher compressibility of the rubber particle compared with those of the conventional mineral aggregates. With an increase in the rubber fraction, the mechanical response of rubber-sand mixtures exhibits two types: sand-like material and rubber-like material. Rubber particle possesses the capacity to prevent the contacted sand particles from sliding at lower rubber fraction, whereas it transmits the applied loadings as the rubber fraction increased. This outcome reinforces the practicability of using recycled rubber tire-sand mixtures as a lightweight backfill in subbase/base applications.

Experimental Investigation of the Mechanical and Durability Properties of Crumb Rubber Concrete.

PubMed

Liu, Hanbing; Wang, Xianqiang; Jiao, Yubo; Sha, Tao

2016-03-07

Recycling waste tire rubber by incorporating it into concrete has become the preferred solution to dispose of waste tires. In this study, the effect of the volume content of crumb rubber and pretreatment methods on the performances of concrete was evaluated. Firstly, the fine aggregate and mixture were partly replaced by crumb rubber to produce crumb rubber concrete. Secondly, the mechanical and durability properties of crumb rubber concrete with different replacement forms and volume contents had been investigated. Finally, the crumb rubber after pretreatment by six modifiers was introduced into the concrete mixture. Corresponding tests were conducted to verify the effectiveness of pretreatment methods as compared to the concrete containing untreated crumb rubber. It was observed that the mechanical strength of crumb rubber concrete was reduced, while durability was improved with the increasing of crumb rubber content. 20% replacement of fine aggregate and 5% replacement of the total mixture exhibited acceptable properties for practical applications. In addition, the results indicated that the modifiers had a positive impact on the mechanical and durability properties of crumb rubber concrete. It avoided the disadvantage of crumb rubber concrete having lower strength and provides a reference for the production of modified crumb rubber concrete.

Experimental Investigation of the Mechanical and Durability Properties of Crumb Rubber Concrete

PubMed Central

Liu, Hanbing; Wang, Xianqiang; Jiao, Yubo; Sha, Tao

2016-01-01

Recycling waste tire rubber by incorporating it into concrete has become the preferred solution to dispose of waste tires. In this study, the effect of the volume content of crumb rubber and pretreatment methods on the performances of concrete was evaluated. Firstly, the fine aggregate and mixture were partly replaced by crumb rubber to produce crumb rubber concrete. Secondly, the mechanical and durability properties of crumb rubber concrete with different replacement forms and volume contents had been investigated. Finally, the crumb rubber after pretreatment by six modifiers was introduced into the concrete mixture. Corresponding tests were conducted to verify the effectiveness of pretreatment methods as compared to the concrete containing untreated crumb rubber. It was observed that the mechanical strength of crumb rubber concrete was reduced, while durability was improved with the increasing of crumb rubber content. 20% replacement of fine aggregate and 5% replacement of the total mixture exhibited acceptable properties for practical applications. In addition, the results indicated that the modifiers had a positive impact on the mechanical and durability properties of crumb rubber concrete. It avoided the disadvantage of crumb rubber concrete having lower strength and provides a reference for the production of modified crumb rubber concrete. PMID:28773298

Chemical Design of Elastomers

DTIC Science & Technology

1987-05-19

of the accelerated vulcanizates. In the 1960s Campbell, Wise and Coran (52) developed characterization techniques to study the effects of compounding...34, Oae, S., Ed., Plenum Press, New York, 1977. 5. Coran , A.Y., "Vulcanization", in "Science and Technology of Rubber," Eirich, F.R., Ed., Academic Press...New York, 1978. 6. Coran , A.Y., Chemtech 106(1983). 7. Coleman, M.M., Shelton J.R. and Koenig, J.L., Ind. Eng. Chem., Prod. Res. Develop. 13, 155

Polyurethanes from fluoroalkyl propyleneglycol polyethers

NASA Technical Reports Server (NTRS)

Trischler, F. D. (Inventor)

1969-01-01

A description is given of highly stable polyurethane polymers prepared by reacting a polyether with a diisocyanate. Compounded stocks of these polymers may be shaped and cured in conventional equipment used in the rubber industry. The solutions are dispersed gels prepared from the polymers and may be used for forming supported or unsupported films for coating fabrics or solid surfaces, and for forming adhesive bonds between a wide variety of plastics, elastomers, fabrics, metals, wood, leather, ceramics and the like.

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. Copyright © 2014 Elsevier Ltd. All rights reserved.

OPPT workplan assessments for medium and long chain ...

EPA Pesticide Factsheets

MCCPs (C14 – C17) and the C18-20 LCCPs are liquid mixtures of chlorinated alkanes. Short chain chlorinated paraffins (SCCPs, C10-C13) have been the focus of coordinated global action (including by US EPA as an action plan chemical), and MCCPs and LCCPs are alternatives to SCCPs for many applications. In the United States, these substances are typically used in oils and metal working fluids to impart stability during high temperature/pressure operations; in plastics/ rubber (PVC) compounding, paints, coatings, adhesives, and sealants as plasticizers and flame retardants. Other assessments have generally found these chemicals to be highly persistent, and some of the congeners are expected to be highly bioaccumulative. MCCPs and LCCPs have been found in all types of environmental media far from their sources, as well as observed in indoor air and house dust, food, fish, human breast milk, and cow’s milk. The assessment will focus on MCCPs (C14-C17) and certain LCCPs (C18-C20) that have received the most international regulatory attention. Based on the screening assessments regarding persistence and bioaccumulation, this assessment will consider PBT aspects of MCCPs and LCCPs, primarily focusing on releases to the environment from the processing and use from metal working fluids and plastics/rubber (PVC) compounding. EPA anticipates issuing draft risk assessments for public review and comment as they are completed. At the conclusion of the review process, if

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

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

Araki, Kunihiro; Kaneko, Shonosuke; Matsumoto, Koki

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 thenmore » 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.« less

Evaluation of the Effect of Silicone Contamination on Various Bond Systems and the Feasibility of Removing the Contamination

NASA Technical Reports Server (NTRS)

Stanley, Stephanie D.

2008-01-01

Silicone is a contaminant that can cause catastrophic failure of a bond system depending on the materials and processes used to fabricate the bond system. Unfortunately, more and more materials are fabricated using silicone. The purpose of this testing was to evaluate which bond systems are sensitive to silicone contamination and whether or not a cleaning process could be utilized to remove the silicone to bring the bond system performance back to baseline. Due to the extensive nature of the testing, attempts will be made to generalize the understanding within classes of substrates, bond systems, and surface preparation and cleaning methods. This study was done by contaminating various metal (steel, Inconel, and aluminum), phenolic (carbon-cloth phenolic [CCP] and glass-cloth phenolic [GCP]), and rubber (natural rubber, asbestos-silicone dioxide filled natural butyldiene rubber [ASNBR]; silica-filled ethylene propylenediene monomer [SFEPDM], and carbon-filled ethylene propylenediene monomer [CFEPDM]) substrates which were then bonded using various adhesives and coatings (epoxy-based adhesives, paints, ablative compounds, and Chemlok adhesives) to determine the effect silicone contamination has on a given bond system's performance. The test configurations depended on the bond system being evaluated. The study also evaluated the feasibility of removing the silicone contamination by cleaning the contaminated substrate prior to bonding. The cleaning processes also varied depending on bond system.

Relationships Between Bioactive Compound Content and
the Antiplatelet and Antioxidant Activities of Six Allium Vegetable Species

PubMed Central

Beretta, Hebe Vanesa; Bannoud, Florencia; Insani, Marina; Berli, Federico; Hirschegger, Pablo; Galmarini, Claudio Rómulo

2017-01-01

Summary Allium sp. vegetables are widely consumed for their characteristic flavour. Additionally, their consumption may provide protection against cardiovascular disease due to their antiplatelet and antioxidant activities. Although antiplatelet and antioxidant activities in Allium sp. are generally recognised, comparative studies of antiplatelet and antioxidant potency among the main Allium vegetable species are lacking. Also, the relationship between organosulfur and phenolic compounds and these biological activities has not been well established. In this study, the in vitro antiplatelet and antioxidant activities of the most widely consumed Allium species are characterised and compared. The species total organosulfur and phenolic content, and the HPLC profiles of 11 phenolic compounds were characterised and used to investigate the relationship between these compounds and antiplatelet and antioxidant activities. Furthermore, antiplatelet activities in chives and shallot have been characterised for the first time. Our results revealed that the strongest antiplatelet agents were garlic and shallot, whereas chives had the highest antioxidant activity. Leek and bunching onion had the weakest both biological activities. Significantly positive correlations were found between the in vitro antiplatelet activity and total organosulfur (R=0.74) and phenolic (TP) content (R=0.73), as well as between the antioxidant activity and TP (R=0.91) and total organosulfur content (R=0.67). Six individual phenolic compounds were associated with the antioxidant activity, with catechin, epigallocatechin and epicatechin gallate having the strongest correlation values (R>0.80). Overall, our results suggest that both organosulfur and phenolic compounds contribute similarly to Allium antiplatelet activity, whereas phenolics, as a whole, are largely responsible for antioxidant activity, with broad variation observed among the contributions of individual phenolic compounds. PMID:28867958

40 CFR 428.50 - Applicability; description of the small-sized general molded, extruded, and fabricated rubber...

Code of Federal Regulations, 2010 CFR

2010-07-01

... RUBBER MANUFACTURING POINT SOURCE CATEGORY Small-Sized General Molded, Extruded, and Fabricated Rubber..., foam rubber backing, rubber cement-dipped goods, and retreaded tires by small-sized plants...

40 CFR 428.70 - Applicability; description of the large-sized general molded, extruded, and fabricated rubber...

Code of Federal Regulations, 2010 CFR

2010-07-01

... RUBBER MANUFACTURING POINT SOURCE CATEGORY Large-Sized General Molded, Extruded, and Fabricated Rubber..., foam rubber backing, rubber cement-dipped goods, and retreaded tires by large-sized plants...

Natural Rubber/Dendrimer Modified Montmorillonite Nanocomposites: Mechanical and Flame-Retardant Properties

PubMed Central

Zhang, Chenyang; Wang, Jincheng

2017-01-01

A series of flame-retardant nanocomposites were established based on compounding of natural rubber (NR) and dendrimer modified flame-retardant organic montmorillonite (FR-DOMt). The merits of these nanocomposites were focused on their better mechanical and flame-retardant properties. X-ray diffractometer (XRD) together with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis revealed that exfoliation, intercalation, or aggregation status in the NRmatrix can be achieved by addition of different amounts of FR-DOMt. The sound effects of blend ratio of FR-DOMt on mechanical, thermal stability, and flame-retardant (FR) properties of NR were studied. The NR/FR-DOMt-20 composite possessed the highest tensile strength, and this resulted from complicated interactions between layered silicates and elastomers. In addition, with loading of 20 phr of FR-DOMt, the flammability parameters of NR, such as heat release rate (HRR), smoke evolution area (SEA), and carbon monoxide (CO) concentration, were obviously reduced from cone calorimeter analysis. PMID:29283385

Used tire recycling to produce granulates: evaluation of occupational exposure to chemical agents.

PubMed

Savary, Barbara; Vincent, Raymond

2011-10-01

Exposure was assessed in four facilities where used tires are turned into rubber granulates. Particulate exposure levels were measured using filter samples and gravimetric analysis. In parallel, volatile organic compounds (VOCs) screening was carried out using samples taken on activated carbon supports, followed by an analysis using a gas chromatograph coupled to a spectrometric detector. The exposure level medians are between 0.58 and 3.95 mg m(-3). Clogging of the textile fiber separation systems can lead to worker exposure; in this case, the measured concentrations can reach 41 mg m(-3). However, in contrast to the data in the literature, VOC levels >1 p.p.m. were not detected. The particulate mixtures deposited on the installation surfaces are complex; some of the chemical agents are toxic to humans. The results of this study indicate significant exposure to complex mixtures of rubber dust. Optimizing exhaust ventilation systems inside the shredders, with a cyclone for example, is essential for reducing the exposure of workers in this rapidly developing sector.

Criteria for asphalt-rubber concrete in civil airport pavements: Mixture design

NASA Astrophysics Data System (ADS)

Roberts, F. L.; Lytton, R. L.; Hoyt, D.

1986-07-01

A mixture design procedure is developed to allow the use of asphalt-rubber binders in concrete for flexible airport pavement. The asphalt-rubber is produced by reacting asphalt with ground, scrap tire rubber to produce the binder for the asphalt-rubber concrete. Procedures for laboratory preparation of alsphalt-rubber binders using an equipment setup that was found by researchers to produce laboratory binders with similar properties to field processes are included. The rubber-asphalt concrete mixture design procedure includes adjustments to the aggregate gradation to permit space for the rubber particles in the asphalt-rubber binder as well as suggested mixing and compaction temperatures, and compaction efforts. While the procedure was used in the laboratory to successfully produce asphalt-rubber concrete mixtures, it should be evaluated in the field to ensure that consistent results can be achieved in a production environment.

Use of recycled chunk rubber asphalt concrete (CRAC) on low volume roads and use of recycled crumb rubber modifier in asphalt pavements. Final report, June 1993-June 1995

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

Hossain, M.; Funk, L.P.; Sadeq, M.A.

1995-06-01

The major objective of this project was to formulate a Chunk Rubber Asphalt Concrete (CRAC) mix for use on low volume roads. CRAC is a rubber modified asphalt concrete product produced by the `dry process` where rubber chunks of 1/2 inch size are used as aggregate in a cold mix with a type C fly ash. The second objective of this project was to develop guidelines concerning the use of rubber modified asphalt concrete hot mix to include: (1) Design methods for use of asphalt-rubber mix for new construction and overlay, (2) Mix design method for asphalt-rubber, and (3) Testmore » method for determining the amount of rubber in an asphalt-rubber concrete for quality control purposes.« less

Formation of hydrocarbon compounds during the hydrocracking of non-edible vegetable oils with cobalt-nickel supported on hierarchical HZSM-5 catalyst

NASA Astrophysics Data System (ADS)

Marlinda, L.; Al-Muttaqii, M.; Roesyadi, A.; Prajitno, D. H.

2017-05-01

The hierarchical Co-Ni/HZSM-5 catalyst with hierarchical pore structure was prepared by desilication and incipient wetness impregnation. Hydrocracking of non-edible vegetable oils at temperature of 400 °C, 20±5 bar for 2 h was performed in the presence of this type of catalyst under hydrogen initial pressure in pressured batch reactor. Non-edible vegetable oils, such as Reutealis trisperma (Blanco) airy shaw (sunan candlenut) and Hevea brasiliensis (rubber seed) were chosen to study the effect of the degree of saturation and lateral chain length on hydrocarbon compounds obtained through hydrocracking. Cerbera manghas oil was also tested for comparison because the composition of fatty acid was different with the other oils The hydrocracking test indicated that liquid product produced has a similar hydrocarbon compounds with petroleum diesel. The most abundant hydrocarbon is pentadecane (n-C15) and heptadecane (n-C17). The high aromatic compounds were found in liquid product produced in hydrocracking of Sunan candlenut oil.

Microwave treatment of vulcanized rubber

DOEpatents

Wicks, George G [Aiken, SC; Schulz, Rebecca L [Aiken, SC; Clark, David E [Gainesville, FL; Folz, Diane C [Gainesville, FL

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.

Theoretical studies on 2-diazo-4,6-dinitrophenol derivatives aimed at finding superior propellants.

PubMed

Liu, Yan; Wang, Lianjun; Wang, Guixiang; Du, Hongchen; Gong, Xuedong

2012-04-01

In an attempt to find superior propellants, 2-diazo-4,6-dinitrophenol (DDNP) and its -NO(2), -NH(2), -CN, -NC, -ONO(2), and -NF(2) derivatives were studied at the B3LYP/6-311++G level of density functional theory (DFT). Sensitivity was evaluated using bond dissociation enthalpies (BDEs) and molecular surface electrostatic potentials. The C-NO(2) bond appears to be the trigger bond during the thermolysis process for these compounds, except for the -ONO(2) and -NF(2) derivatives. Electrostatic potential results show that electron-withdrawing substituents make the charge imbalance more anomalous, which may change the strength of the bond, especially the weakest trigger bond. Most of the DDNP derivatives have the impact sensitivities that are higher than that of DDNP, making them favorable for use as solid propellants in micro-rockets. The theoretical densities (ρ), heats of formation (HOFs), detonation energies (Q), detonation pressures (P), and detonation velocities (D) of the compounds were estimated. The effects of various substituent groups on ρ, HOF, Q, D, and P were investigated. Some derivatives exhibit perfect detonation properties. The calculated relative specific impulses (I (r,sp)) of all compounds except for -NH(2) derivatives were higher than that of DDNP, and also meet the requirements of propellants.

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.

Effect of superhydrophobicity on surface damage of silicone rubber under AC voltage

NASA Astrophysics Data System (ADS)

Li, Yufeng; Jin, Haiyun; Nie, Shichao; Tong, Cheng; Gao, Naikui

2018-03-01

In this paper, the influence of superhydrophobicity on the surface damage of silicone rubber is studied. On a common silicone rubber surface, a droplet can become elongated, and arc discharge induced by the droplet can cause tracking on the silicone rubber surface. However, for a superhydrophobic silicone rubber surface, a droplet can leave the silicone rubber due to the low adhesion of the superhydrophobic surface. Accordingly, arc discharge caused by the droplet does not occur, and the surface of the silicone rubber is not affected. Results demonstrate that using a superhydrophobic surface has a significant effect on limiting the surface damage of silicone rubber.

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.

Altered levels of the Taraxacum kok-saghyz (Russian dandelion) small rubber particle protein, TkSRPP3, result in qualitative and quantitative changes in rubber metabolism.

PubMed

Collins-Silva, Jillian; Nural, Aise Taban; Skaggs, Amanda; Scott, Deborah; Hathwaik, Upul; Woolsey, Rebekah; Schegg, Kathleen; McMahan, Colleen; Whalen, Maureen; Cornish, Katrina; Shintani, David

2012-07-01

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 studies suggest that SRPP plays a role in rubber biosynthesis, in vivo evidence is lacking to support this hypothesis. To address this issue, a transgene approach was taken in Taraxacum kok-saghyz (Russian dandelion or Tk) to determine if altered SRPP levels would influence rubber biosynthesis. Three dandelion SRPPs were found to be highly abundant on dandelion rubber particles. The most abundant particle associated SRPP, TkSRPP3, showed temporal and spatial patterns of expression consistent with patterns of natural rubber accumulation in dandelion. To confirm its role in rubber biosynthesis, TkSRPP3 expression was altered in Russian dandelion using over-expression and RNAi methods. While TkSRPP3 over-expressing lines had slightly higher levels of rubber in their roots, relative to the control, TkSRPP3 RNAi lines showed significant decreases in root rubber content and produced dramatically lower molecular weight rubber than the control line. Not only do results here provide in vivo evidence of TkSRPP proteins affecting the amount of rubber in dandelion root, but they also suggest a function in regulating the molecular weight of the cis-1, 4-polyisoprene polymer. Copyright © 2012 Elsevier Ltd. All rights reserved.

Geospatial application for the identification and monitoring of rubber smallholders in the Malaysian state of Negeri Sembilan

NASA Astrophysics Data System (ADS)

Hafiz Mohd Hazir, Mohd; Muda, Tuan Mohamad Tuan

2016-06-01

The Malaysian rubber industry, especially in the upstream sector, is much dependent on smallholders to produce latex or cup lumps. Identification and monitoring of rubber smallholders are essential tasks when it comes to the Malaysian rubber industry's sustainability. The authorised agencies who support the rubber smallholders can do better planning, arranging, and managing. This paper introduces a method of calculating the total number of smallholders as well as identifying the location of their planted rubber area. The scope of this study only focused on land owners as rubber smallholders in the selected study area of Negeri Sembilan. The land use map provided by the Department of Agriculture Malaysia gave information on distribution of rubber area in Malaysia, while the cadastral map from the Department of Survey and Mapping Malaysia was specifically used for identifying land owners of each rubber parcel or rubber lot. Both data were analyzed and processed with ArcGIS software to extract the information, and the results were then compared to the Malaysian Rubber Board smallholders database.

Experimental comparison of manufacturing techniques of toughened and nanoreinforced polyamides

NASA Astrophysics Data System (ADS)

Siengchin, S.; Bergmann, C.; Dangtungee, R.

2011-11-01

Composites consisting of polyamide-6 (PA-6), nitrile rubber (NBR), and sodium fluorohectorite (FH) or alumina silicate (Sungloss; SG) were produced by different techniques with latex precompounding. Their tensile and thermomechanical properties were determined by using tensile tests and a dynamic-mechanical analysis, performed at various temperatures. The PA-6/NBR composite systems produced by the direct melt compounding outperformed those obtained by using the masterbatch technique with respect to the strength and ductility, but the latter ones had a higher storage modulus.

Nanoscale Mechanism of Composite Reinforcement by Fibers and Filler, Theoretical Computation and Experimental Validation of the Theory Using Rubber/Short Carbon Fiber Compounds

DTIC Science & Technology

2005-06-24

for an adhesion-active surface. 2.8.2 Dupre’s equation Let adhesive interaction between two bodies take place. Dupre’s equation defines the...connection between work of external forces on system of two bodies with adhesive interaction contact, the potential energies these bodies and the energy...Lagrangian of system of two bodies with adhesion interaction is equal half of work of external forces enclosed to this system” With the help of

Fire Resistant, Moisture Barrier Membrane

NASA Technical Reports Server (NTRS)

St.Clair, Terry L. (Inventor)

2000-01-01

A waterproof and breathable, fire-resistant laminate is provided for use in tents, garments, shoes, and covers, especially in industrial, military and emergency situations. The laminate permits water vapor evaporation while simultaneously preventing liquid water penetration. Further, the laminate is fire-resistant and significantly reduces the danger of toxic compound production when exposed to flame or other high heat source. The laminate may be applied to a variety of substrates and is comprised of a silicone rubber and plurality of fire-resistant, inherently thermally-stable polyimide particles.

Fire Resistant, Moisture Barrier Membrane

NASA Technical Reports Server (NTRS)

St.Clair, Terry L. (Inventor)

1998-01-01

A waterproof and breathable, fire-resistant laminate is provided for use in tents, garments, shoes, and covers, especially in industrial, military and emergency situations. The laminate permits water vapor evaporation while simultaneously preventing liquid water penetration. Further, the laminate is fire-resistant and significantly reduces the danger of toxic compound production when exposed to flame or other high heat source. The laminate may be applied to a variety of substrates and is comprised of a silicone rubber and plurality of fire-resistant, inherently thermally-stable polyimide particles.

Experimental Study of the Oxidation, Ignition, and Soot Formation Characteristics of Jet Fuel

DTIC Science & Technology

2010-09-29

section and controls the heat flux applied to six heated zones along the 4.11 m long driven section, and 2.5 cm thick mineral wool insulation that...The mixing manifold was insulated with 1.1 cm thick silicon foam rubber insulation, and the mixing vessel was insulated with 2.5 cm- thick mineral ... wool insulation. Experimental work for a number of compounds with variation in manifold and tank heating showed no observable difference in measured

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.

40 CFR 428.20 - Applicability; description of the emulsion crumb rubber subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... emulsion crumb rubber subcategory. 428.20 Section 428.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS RUBBER MANUFACTURING POINT SOURCE CATEGORY Emulsion Crumb Rubber Subcategory § 428.20 Applicability; description of the emulsion crumb rubber subcategory...

40 CFR 428.20 - Applicability; description of the emulsion crumb rubber subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... emulsion crumb rubber subcategory. 428.20 Section 428.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS RUBBER MANUFACTURING POINT SOURCE CATEGORY Emulsion Crumb Rubber Subcategory § 428.20 Applicability; description of the emulsion crumb rubber subcategory...

21 CFR 177.1480 - Nitrile rubber modified acrylonitrile-methyl acrylate copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Nitrile rubber modified acrylonitrile-methyl... Nitrile rubber modified acrylonitrile-methyl acrylate copolymers. Nitrile rubber modified acrylonitrile... rubber modified acrylonitrile-methyl acrylate copolymers consist of basic copolymers produced by the...

Effect of non-rubber constituents on Guayule and Hevea rubber intrinsic properties

USDA-ARS?s Scientific Manuscript database

To meet the increasing demand for natural rubber (NR), currently sourced from the tropical rubber tree Hevea brasiliensis, and address price volatility and steadily increasing labor costs, alternate rubber-producing species are in commercial development. One of these, guayule (Parthenium argentatum)...

Mechanical Behavior and Fatigue Studies of Rubber Components Used in Tracked Vehicles

DTIC Science & Technology

2010-08-17

durability to this elastomers and polybutadiene is rubber , which gives rubber -like properties. SBR has good abrasion resistance and good aging ...SIMULATION, TESTING AND VALIDATION (MSTV) MINI-SYMPOSIUM AUGUST 17-19 DEARBORN, MICHIGAN MECHANICAL BEHAVIOR AND FATIGUE STUDIES OF RUBBER COMPONENTS USED...Analytics Group US Army TARDEC Warren, MI ABSTRACT In this study, a styrene butadiene rubber , which is similar to the rubber used in road wheel

Reinforcement effect of soy protein nanoparticles in amine-modified natural rubber latex

USDA-ARS?s Scientific Manuscript database

Mechanical properties of natural rubber reinforced with soy protein nanoparticles are useful for various rubber applications. However, the properties is further improved by improving interactions between soy protein and rubber. A novel method is used to modify particle surface of natural rubber late...

Particle reinforced composites from acrylamide modified blend of styrene-butadiene and natural rubber

USDA-ARS?s Scientific Manuscript database

Blends of styrene-butadiene rubber and natural rubber that provide balanced properties were modified with acrylamide and reinforced with soy protein particles. The rubber composites show improved mechanical properties. Both modified rubber and composites showed a faster curing rate. The crosslinking...

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.

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.

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

USDA-ARS?s Scientific Manuscript database

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...

Chlorinated rubbers with advanced properties for tire industry

NASA Astrophysics Data System (ADS)

Mikhaylov, I. A.; Sukhareva, K. V.; Andriasyan, Yu. O.; Popov, A. A.

2017-12-01

The paper investigates the production and processing of halide-modified chlorinated rubbers, such as isobutylene isoprene rubber and ethylene-propylene-diene-monomer rubber (IIR and EPDM), which are perspective in terms of application in rubber industry. Prospects for their production and application are determined by the specific properties of these rubbers (low gas permeability of IIR, high heat and ozone resistance of EPDM). These properties are governed by the structure of both initial IIR and EPDM and chlorinated rubbers (ChIIR and ChEPDM). A new alternative technology of obtaining chlorinated elastomers based on solid-phase mechanochemical halide modification is proposed. Novel chlorinated polyolefin rubbers obtained by the developed technology show good technological properties under industrial production conditions due to enhanced covulcanization.

Electrospinning of PVC with natural rubber

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

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

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 morphologymore » 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.« less

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.

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

2016-02-23

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.

Silicon(IV) phthalocyanines substituted axially with different nucleoside moieties. Effects of nucleoside type on the photosensitizing efficiencies and in vitro photodynamic activities.

PubMed

Zheng, Bi-Yuan; Shen, Xiao-Min; Zhao, Dong-Mei; Cai, Yi-Bin; Ke, Mei-Rong; Huang, Jian-Dong

2016-06-01

A series of new silicon(IV) phthalocyanines (SiPcs) di-substituted axially with different nucleoside moieties have been synthesized and evaluated for their singlet oxygen quantum yields (ΦΔ) and in vitro photodynamic activities. The adenosine-substituted SiPc shows a lower photosensitizing efficiency (ΦΔ=0.35) than the uridine- and cytidine-substituted analogs (ΦΔ=0.42-0.44), while the guanosine-substituted SiPc exhibits a weakest singlet oxygen generation efficiency with a ΦΔ value down to 0.03. On the other hand, replacing axial adenosines with chloro-modified adenosines and purines can result in the increase of photogenerating singlet oxygen efficiencies of SiPcs. The formed SiPcs 1 and 2, which contain monochloro-modified adenosines and dichloro-modified purines respectively, appear as efficient photosensitizers with ΦΔ of 0.42-0.44. Both compounds 1 and 2 present high photocytotoxicities against HepG2 and BGC823 cancer cells with IC50 values ranging from 9nM to 33nM. The photocytotoxicities of these two compounds are remarkably higher than the well-known anticancer photosensitizer, chlorin e6 (IC50=752nM against HepG2 cells) in the same condition. As revealed by confocal microscopy, for both cell lines, compound 1 can essentially bind to mitochondria, while compound 2 is just partially localized in mitochondria. In addition, the two compounds induce cell death of HepG2 cells likely through apoptosis. Copyright © 2016 Elsevier B.V. All rights reserved.

Characterization of rubber particles and rubber chain elongation in Taraxacum koksaghyz

PubMed Central

2010-01-01

Background Natural rubber is a biopolymer with exceptional qualities that cannot be completely replaced using synthetic alternatives. Although several key enzymes in the rubber biosynthetic pathway have been isolated, mainly from plants such as Hevea brasiliensis, Ficus spec. and the desert shrub Parthenium argentatum, there have been no in planta functional studies, e.g. by RNA interference, due to the absence of efficient and reproducible protocols for genetic engineering. In contrast, the Russian dandelion Taraxacum koksaghyz, which has long been considered as a potential alternative source of low-cost natural rubber, has a rapid life cycle and can be genetically transformed using a simple and reliable procedure. However, there is very little molecular data available for either the rubber polymer itself or its biosynthesis in T. koksaghyz. Results We established a method for the purification of rubber particles - the active sites of rubber biosynthesis - from T. koksaghyz latex. Photon correlation spectroscopy and transmission electron microscopy revealed an average particle size of 320 nm, and 13C nuclear magnetic resonance (NMR) spectroscopy confirmed that isolated rubber particles contain poly(cis-1,4-isoprene) with a purity >95%. Size exclusion chromatography indicated that the weight average molecular mass (w) of T. koksaghyz natural rubber is 4,000-5,000 kDa. Rubber particles showed rubber transferase activity of 0.2 pmol min-1 mg-1. Ex vivo rubber biosynthesis experiments resulted in a skewed unimodal distribution of [1-14C]isopentenyl pyrophosphate (IPP) incorporation at a w of 2,500 kDa. Characterization of recently isolated cis-prenyltransferases (CPTs) from T. koksaghyz revealed that these enzymes are associated with rubber particles and are able to produce long-chain polyprenols in yeast. Conclusions T. koksaghyz rubber particles are similar to those described for H. brasiliensis. They contain very pure, high molecular mass poly(cis-1,4-isoprene) and the chain elongation process can be studied ex vivo. Because of their localization on rubber particles and their activity in yeast, we propose that the recently described T. koksaghyz CPTs are the major rubber chain elongating enzymes in this species. T. koksaghyz is amenable to genetic analysis and modification, and therefore could be used as a model species for the investigation and comparison of rubber biosynthesis. PMID:20170509

Construction of Pará rubber tree genome and multi-transcriptome database accelerates rubber researches.

PubMed

Makita, Yuko; Kawashima, Mika; Lau, Nyok Sean; Othman, Ahmad Sofiman; Matsui, Minami

2018-01-19

Natural rubber is an economically important material. Currently the Pará rubber tree, Hevea brasiliensis is the main commercial source. Little is known about rubber biosynthesis at the molecular level. Next-generation sequencing (NGS) technologies brought draft genomes of three rubber cultivars and a variety of RNA sequencing (RNA-seq) data. However, no current genome or transcriptome databases (DB) are organized by gene. A gene-oriented database is a valuable support for rubber research. Based on our original draft genome sequence of H. brasiliensis RRIM600, we constructed a rubber tree genome and transcriptome DB. Our DB provides genome information including gene functional annotations and multi-transcriptome data of RNA-seq, full-length cDNAs including PacBio Isoform sequencing (Iso-Seq), ESTs and genome wide transcription start sites (TSSs) derived from CAGE technology. Using our original and publically available RNA-seq data, we calculated co-expressed genes for identifying functionally related gene sets and/or genes regulated by the same transcription factor (TF). Users can access multi-transcriptome data through both a gene-oriented web page and a genome browser. For the gene searching system, we provide keyword search, sequence homology search and gene expression search; users can also select their expression threshold easily. The rubber genome and transcriptome DB provides rubber tree genome sequence and multi-transcriptomics data. This DB is useful for comprehensive understanding of the rubber transcriptome. This will assist both industrial and academic researchers for rubber and economically important close relatives such as R. communis, M. esculenta and J. curcas. The Rubber Transcriptome DB release 2017.03 is accessible at http://matsui-lab.riken.jp/rubber/ .

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.

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

USDA-ARS?s Scientific Manuscript database

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...

Comprehensive evaluation of the long-term performance of rubberized pavement, phase I : laboratory study of rubberized asphalt mix performance.

DOT National Transportation Integrated Search

2012-12-01

Crumb rubber, made from scrap tires, has been introduced into the production of different types of hot : mix asphalt (HMA) in either a wet or dry process. In the wet process, the crumb rubber and binder are : completely mixed to form asphalt rubber (...

21 CFR 872.6300 - Rubber dam and accessories.

Code of Federal Regulations, 2012 CFR

2012-04-01

... center intended to isolate a tooth from fluids in the mouth during dental procedures, such as filling a... center. The device includes the rubber dam, rubber dam clamp, rubber dam frame, and forceps for a rubber... sexually transmitted diseases through oral sex; those devices are classified as condoms in § 884.5300 of...

21 CFR 872.6300 - Rubber dam and accessories.

Code of Federal Regulations, 2011 CFR

2011-04-01

... center intended to isolate a tooth from fluids in the mouth during dental procedures, such as filling a... center. The device includes the rubber dam, rubber dam clamp, rubber dam frame, and forceps for a rubber... sexually transmitted diseases through oral sex; those devices are classified as condoms in § 884.5300 of...

21 CFR 872.6300 - Rubber dam and accessories.

Code of Federal Regulations, 2014 CFR

2014-04-01

... center intended to isolate a tooth from fluids in the mouth during dental procedures, such as filling a... center. The device includes the rubber dam, rubber dam clamp, rubber dam frame, and forceps for a rubber... sexually transmitted diseases through oral sex; those devices are classified as condoms in § 884.5300 of...

21 CFR 872.6300 - Rubber dam and accessories.

Code of Federal Regulations, 2010 CFR

2010-04-01

... center intended to isolate a tooth from fluids in the mouth during dental procedures, such as filling a... center. The device includes the rubber dam, rubber dam clamp, rubber dam frame, and forceps for a rubber... sexually transmitted diseases through oral sex; those devices are classified as condoms in § 884.5300 of...

21 CFR 872.6300 - Rubber dam and accessories.

Code of Federal Regulations, 2013 CFR

2013-04-01

... center intended to isolate a tooth from fluids in the mouth during dental procedures, such as filling a... center. The device includes the rubber dam, rubber dam clamp, rubber dam frame, and forceps for a rubber... sexually transmitted diseases through oral sex; those devices are classified as condoms in § 884.5300 of...

40 CFR 63.498 - Back-end process provisions-recordkeeping.

Code of Federal Regulations, 2011 CFR

2011-07-01

... be the crumb rubber dry weight of the rubber leaving the stripper. (iv) The organic HAP content of... be the crumb rubber dry weight of the crumb rubber leaving the stripper. (iii) The hourly average of... test runs. (1) The uncontrolled residual organic HAP content in the latex or dry crumb rubber, as...

40 CFR 63.498 - Back-end process provisions-recordkeeping.

Code of Federal Regulations, 2012 CFR

2012-07-01

... be the crumb rubber dry weight of the rubber leaving the stripper. (iv) The organic HAP content of... be the crumb rubber dry weight of the crumb rubber leaving the stripper. (iii) The hourly average of... test runs. (1) The uncontrolled residual organic HAP content in the latex or dry crumb rubber, as...

40 CFR 63.498 - Back-end process provisions-recordkeeping.

Code of Federal Regulations, 2014 CFR

2014-07-01

... be the crumb rubber dry weight of the rubber leaving the stripper. (iv) The organic HAP content of... be the crumb rubber dry weight of the crumb rubber leaving the stripper. (iii) The hourly average of... test runs. (1) The uncontrolled residual organic HAP content in the latex or dry crumb rubber, as...

40 CFR 63.498 - Back-end process provisions-recordkeeping.

Code of Federal Regulations, 2013 CFR

2013-07-01

... be the crumb rubber dry weight of the rubber leaving the stripper. (iv) The organic HAP content of... be the crumb rubber dry weight of the crumb rubber leaving the stripper. (iii) The hourly average of... test runs. (1) The uncontrolled residual organic HAP content in the latex or dry crumb rubber, as...

Genomic validation of PB 260 clone of rubber (Hevea brasiliensis) at Cikumpay Plantation by SSR marker

NASA Astrophysics Data System (ADS)

Royani, J. I.; Safarrida, A.; Rachmawati, I.; Khairiyah, H.; Mustika, I. P.; Suyono, A.; Rudiyana, Y.; Kubil; Nurjaya; Arianto, A.

2017-05-01

Rubber from Hevea brasiliensis is the only commercial natural rubber in the world. Propagation of rubber trees usually done by grafting and seed germination. BPPT had been producing rubber tree by in vitro technique with embryo somatic methods. Validation of mother plant for in vitro propagation is important to compare between mother plant and propagated plants. The aim for this research was to validation of PB 260 clone that planted at Cikumpay Plantation by SSR marker. Sampling of 10 rubber leaves were done at Cikumpay Plantation based on GPS position from the area of PB 260 clone. Rubber leaves were isolated with CTAB modification method to obtained DNA. Four of SSR primers from rubber, i.e.: hmac 4, hmac 5, hmct 1, and hmct 5, were used as primers to amplification of rubber DNA. The result showed that no band that different from 10 rubber of PB 260 clone at Cikumpay Plantation. This research will continue to compare genomic validation between mother plant and propagated plants that had been produced from BPPT.

Subcellular localization and interactions among rubber particle proteins from Hevea brasiliensis.

PubMed

Brown, Daniel; Feeney, Mistianne; Ahmadi, Mathin; Lonoce, Chiara; Sajari, Roslinda; Di Cola, Alessandra; Frigerio, Lorenzo

2017-11-02

Natural rubber (polyisoprene) from the rubber tree Hevea brasiliensis is synthesized by specialized cells called laticifers. It is not clear how rubber particles arise, although one hypothesis is that they derive from the endoplasmic reticulum (ER) membrane. Here we cloned the genes encoding four key proteins found in association with rubber particles and studied their intracellular localization by transient expression in Nicotiana benthamiana leaves. We show that, while the cis-prenyltransferase (CPT), responsible for the synthesis of long polyisoprene chains, is a soluble, cytosolic protein, other rubber particle proteins such as rubber elongation factor (REF), small rubber particle protein (SRPP) and Hevea rubber transferase 1-REF bridging protein (HRBP) are associated with the endoplasmic reticulum (ER). We also show that SRPP can recruit CPT to the ER and that interaction of CPT with HRBP leads to both proteins relocating to the plasma membrane. We discuss these results in the context of the biogenesis of rubber particles. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

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.

The weakest t-norm based intuitionistic fuzzy fault-tree analysis to evaluate system reliability.

PubMed

Kumar, Mohit; Yadav, Shiv Prasad

2012-07-01

In this paper, a new approach of intuitionistic fuzzy fault-tree analysis is proposed to evaluate system reliability and to find the most critical system component that affects the system reliability. Here weakest t-norm based intuitionistic fuzzy fault tree analysis is presented to calculate fault interval of system components from integrating expert's knowledge and experience in terms of providing the possibility of failure of bottom events. It applies fault-tree analysis, α-cut of intuitionistic fuzzy set and T(ω) (the weakest t-norm) based arithmetic operations on triangular intuitionistic fuzzy sets to obtain fault interval and reliability interval of the system. This paper also modifies Tanaka et al.'s fuzzy fault-tree definition. In numerical verification, a malfunction of weapon system "automatic gun" is presented as a numerical example. The result of the proposed method is compared with the listing approaches of reliability analysis methods. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

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.

Chrome-tanned leather shavings as a filler of butadiene-acrylonitrile rubber.

PubMed

Przepiórkowska, A; Chrońska, K; Zaborski, M

2007-03-06

The noxious wastes from the tanning industry such as chrome-tanned leather shavings were used as the only filler of rubber mixes containing carboxylated butadiene-acrylonitrile rubber (XNBR) or butadiene-acrylonitrile rubber (NBR), and a dispersing agent Limanol PEV (Schill & Seilacher). The best form addition of leather powder to the rubber mixes is mixed the waste protein with zinc oxide. The leather powder added to the rubber mixes improves the mechanical properties: tensile strength (T(s)), elongation at break (epsilon(b)) and increase the cross-linking density of carboxylated XNBR and NBR rubber mixes. Satisfactory results of these studies are presented in this work.

Shear modulus and damping ratio of natural rubber containing carbon nanotubes

NASA Astrophysics Data System (ADS)

Ismail, R.; Ibrahim, A.; Rusop, M.; Adnan, A.

2018-05-01

This paper presents the results of an investigation into the potential application of Natural rubber (NR) containing Carbon Nanotubes (CNTs) by measuring its shear modulus and damping ratio. Four different types of rubber specimens which fabricated with different MWCNT loadings: 0 wt% (pure natural rubber), 1 wt%, 3 wt%, and 5 wt%. It is observed that the shear modulus and damping ratio of CNTs filled rubber composites are remarkably higher than that of raw rubber indicating the inherent reinforcing potential of CNTs.

Thermolysis of scrap tire and rubber in sub/super-critical water.

PubMed

Li, Qinghai; Li, Fuxin; Meng, Aihong; Tan, Zhongchao; Zhang, Yanguo

2018-01-01

The rapid growth of waste tires has become a serious environmental issue. Energy and material recovery is regarded as a promising use for waste tires. Thermolysis of scrap tire (ST), natural rubber (NR), and styrene-butadiene rubber (SBR) was carried out in subcritical and supercritical water using a temperature-pressure independent adjustable batch tubular reactor. As a result, oil yields increased as temperature and pressure increased, and they reached maximum values as the state of water was near the critical point. However, further increases in water temperature and pressure reduced the oil yields. The maximum oil yield of 21.21% was obtained at 420 °C and 18 MPa with a reaction time of 40 min. The relative molecular weights of the chemicals in the oil products were in the range of 70-140 g/mole. The oil produced from ST, NR, and SBR contained similar chemical compounds, but the oil yield of SR was between those of NR and SBR. The oil yield from thermolysis of subcritical or supercritical water should be further improved. The main gaseous products, including CH 4 , C 2 H 2 , C 2 H 4 , C 2 H 6 , and C 3 H 8 , increased with reaction time, temperature, and pressure, whereas the solid residues, including carbon black and impurities, decreased. These results provide useful information to develop a sub/super-critical water thermolysis process for energy and material regeneration from waste tires. Copyright © 2017 Elsevier Ltd. All rights reserved.

Eco-friendly rubberized cotton fabric roller for ginning machines.

PubMed

Iyer, G V

2007-01-01

This article discusses the pollution caused by chrome composite leather-clad (CCLC) rollers commonly used in cotton roller ginning mills and suggests an alternative roller material. CCLC rollers contain about 18,000 to 36,000 mg/kg (ppm) total chromium in trivalent and hexavalent forms, which are toxic to human health and carcinogenic. When seed-cotton is processed in double roller (DR) ginning machines, the lint is contaminated with chromium, and chromium particles are carried into the spun yarns and cotton by-products. Specifically, due to persistent rubbing of the leather-clad roller over the stationary knife during the ginning process, the lint is contaminated with about 140 to 1990 ppm of chromium, and the spun yarns and cotton by-products contain about 100 to 200 ppm, far in excess of the standard limit of 0.1 ppm. Gin and mill workers are directly exposed to this carcinogenic substance. To offset this problem, pollution-free rubberized cotton fabric (RCF) rollers have been fabricated and tested in roller gins. The RCF roller covering is made of multiple layers of fabric bonded together using a white rubber compound, which has a surface finish conducive to high ginning efficiency. This eliminates chromium contamination and pollution during the ginning process. On the basis of the design and development of various test rollers and subsequent evaluation studies, the performance of pollution-free RCF rollers has been demonstrated with reference to their commercial benefit and eco-friendliness in cotton ginning mills.

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

Analysis of sulfidic linkages formed in natural rubber latex medical gloves by using X-ray absorption near edge structure

NASA Astrophysics Data System (ADS)

Chankrachang, M.; Limphirat, W.; Yongyingsakthavorn, P.; Nontakaew, U.; Tohsan, A.

2017-09-01

A study of sulfidic linkages formed in natural rubber (NR) latex medical gloves by using X-ray Absorption Near Edge Structure (XANES) is presented in this paper. The NR latex compound was prepared by using prevulcanization method, that is, it was prevulcanized at room temperature for 24 hrs before utilization. After the 24 hrs of prevulcanization, the latex film samples were obtained by dipping process. The dipped films were subjected to vulcanize at 110°C for 5 to 25 min. It was observed that after the compound was prevulcanized for 24 hrs, polysulfidic linkages were mainly formed in the sample. It was however found that after curing at 110°C for 5-25 min, the polysulfidic linkages are tended to change into disulfide linkages. Especially, in the case of 25 minutes cured sample, disulfide linkages are found to be the main linkages. In term of tensile strength, it was observed that when cure time increased from 5 - 10 min, tensile strengths were also increased. But when the cure time of the film is 25 minutes, tensile strength was slightly dropped. The dropped of tensile strength when cure time is longer than 10 minutes can be ascribed to a degradation of polysulfidic and disulfidic linkages during curing. Therefore, by using XANES analysis, it was found to be very useful to understand the cure characteristic, thus it can be very helpful to optimize cure time and tensile properties of the product.

Adhesion of Silicone Elastomer Seals for NASA's Crew Exploration Vehicle

NASA Technical Reports Server (NTRS)

deGroh, Henry C., III; Miller, Sharon K. R.; Smith, Ian M.; Daniels, Christopher C.; Steinetz, Bruce M

2008-01-01

Silicone rubber seals are being considered for a number of interfaces on NASA's Crew Exploration Vehicle (CEV). Some of these joints include the docking system, hatches, and heat shield-to-back shell interface. A large diameter molded silicone seal is being developed for the Low Impact Docking System (LIDS) that forms an effective seal between the CEV and International Space Station (ISS) and other future Constellation Program spacecraft. Seals between the heat shield and back shell prevent high temperature reentry gases from leaking into the interface. Silicone rubber seals being considered for these locations have inherent adhesive tendencies that would result in excessive forces required to separate the joints if left unchecked. This paper summarizes adhesion assessments for both as-received and adhesion-mitigated seals for the docking system and the heat shield interface location. Three silicone elastomers were examined: Parker Hannifin S0899-50 and S0383-70 compounds, and Esterline ELA-SA-401 compound. For the docking system application various levels of exposure to atomic oxygen (AO) were evaluated. Moderate AO treatments did not lower the adhesive properties of S0899-50 sufficiently. However, AO pretreatments of approximately 10(exp 20) atoms/sq cm did lower the adhesion of S0383-70 and ELA-SA-401 to acceptable levels. For the heat shield-to-back shell interface application, a fabric covering was also considered. Molding Nomex fabric into the heat shield pressure seal appreciably reduced seal adhesion for the heat shield-to-back shell interface application.

Research on Extrusion of Rubber Composites Reinforced by Short Fibers Orientation Based on FEA

NASA Astrophysics Data System (ADS)

Zhang, Dewei; Wang, Chuansheng; Shen, Bo; Li, Shaoming; Bian, Huiguang

2018-06-01

In recent years, rubber composites reinforced by short fibers has been researched deeply, because of its good performances such as higher wear resistance, higher cut resistance and so on. Some research results indicated that if short fibers get orientation in rubber composites, the performances of rubber products could be promoted greatly. But how to make short fibers get orientation in rubber matrix during extrusion is still a real problem. And there are many parameters affect the short fibers orientation. So, in this paper, the effects of die structure including expansion-die and dam-expansion-die on extrusion flow field of short fiber and rubber composite material during extrusion process has been researched by Polyflow. And the FEA results about the pressure field, velocity field and the velocity vector of the rubber composites flow field indicate that, comparing with expansion-die and the dam-expansion-die, the latter one is better for the extrusion process of rubber composites and making short fibers get radial orientation in rubber matrix.

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)

Development of magnetorheological elastomers based on Deproteinised natural rubber as smart damping materials

NASA Astrophysics Data System (ADS)

Ismail, Nik Intan Nik; Kamaruddin, Shamsul

2017-12-01

Magnetorheological elastomers (MREs) are composite materials consist of micron-sized magnetizable particles carbonyl iron particles [CIPs]) embedded in a soft elastomer matrix. MRE technology offers variable stiffness and damping properties under the influence of a magnetic field. Herein, the feasibility of incorporating a new generation specialty rubber, Pureprena as a matrix for MREs was investigated. Pureprena or Deproteinised Natural Rubber (DPNR) is a specialty natural rubber that has good dynamic properties, particularly with respect to damping parameters. DPNR was compounded with 60 wt% of CIPs to fabricate MREs. The performance of the DPNR-based MRE was measured in terms of tensile strength, dynamic properties, and magnetorheological (MR) effect and compared with polyisoprene (IR)-based MRE with the same amount of CIPs. Dynamic Mechanical Analyzer (DMA) showed that the loss factor in the glass transition region of the DPNR-based MRE was higher than that of the IR-based MRE, indicating better damping properties. Further investigation was undertaken using a servo-hydraulic testing machine to characterise the effect of strain amplitude and frequency on the dynamic properties (e.g. damping coefficient) of MREs at zero magnetic fields. The results demonstrate that DPNR-based MREs possess a comparable damping coefficient to that of IR-based MREs. In addition, MR effect, which relates to the ratio between elastic modulus with applied magnetic field (on-state) to the same modulus without applied fields (off-state), was measured using a parallel plate rheometer. As a result, DPNR-based MREs have improved MR effect than that of IR-based MREs. Moreover, variable stiffness is obtained when the magnetic field was increased to 0.8T. Loss factor or tan δ of MREs was found to vary against different magnetic fields. Finally, MREs with varied stiffness and damping were found to have potential as active control devices for smart damping materials.

Natural rubber (NR) biosynthesis: perspectives from polymer chemistry

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

Barkakaty, Balaka

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 polyisoprenesmore » 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.« less

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.

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.

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.

Biodiesel production methods of rubber seed oil: a review

NASA Astrophysics Data System (ADS)

Ulfah, M.; Mulyazmi; Burmawi; Praputri, E.; Sundari, E.; Firdaus

2018-03-01

The utilization of rubber seed as raw material of biodiesel production is seen highly potential in Indonesia. The availability of rubber seeds in Indonesia is estimated about 5 million tons per annum, which can yield rubber seed oil about 2 million tons per year. Due to the demand of edible oils as a food source is tremendous and the edible oil feedstock costs are far expensive to be used as fuel, production of biodiesel from non-edible oils such as rubber seed is an effective way to overcome all the associated problems with edible oils. Various methods for producing biodiesel from rubber seed oil have been reported. This paper introduces an optimum condition of biodiesel production methods from rubber seed oil. This article was written to be a reference in the selection of methods and the further development of biodiesel production from rubber seed oil. Biodiesel production methods for rubber seed oils has been developed by means of homogeneous catalysts, heterogeneous catalysts, supercritical method, ultrasound, in-situ and enzymatic processes. Production of biodiesel from rubber seed oil using clinker loaded sodium methoxide as catalyst is very interesting to be studied and developed further.

Crumb Rubber Recycling in Enhancing Damping Properties of Concrete

NASA Astrophysics Data System (ADS)

Sugapriya, P.; Ramkrishnan, R.

2018-02-01

Damping plays a major role in the design of roadside structures that gets affected due to vibrations transmitted from moving traffic. In this study, fine aggregates were partially replaced with crumb rubber in concrete, at varying percentages of 5, 10, 15 and 20% by weight. Three different sets of concrete, mixed with crumb rubber were prepared using raw rubber, treated rubber and treated rubber with partial replacement of cement. Cement was partially replaced with Ultra-Fine Ground Granulated Blast furnace Slag (UFGGBS) for this study. Samples were cast, cured and tested for various properties on the 7th and 28th day. The damping ratio and frequency of the peak value from a number of waves in rubber incorporated beams were found out using a FFT Analyser along with its Strength, Damping and Sorptivity characteristics. SEM analysis was conducted to analyse the micro structural bonding between rubber and concrete. The mode shapes of pavement slabs were modelled and analysed using a FEM tool, ANSYS. From the results, the behaviour of the three sets of rubberized concrete were compared and analysed, and an optimum percentage for crumb rubber and UFGGBS was proposed to achieve best possible damping without compromising the strength properties.

Generation of Hydrogen and Methane during Experimental Low-Temperature Reaction of Ultramafic Rocks with Water.

PubMed

McCollom, Thomas M; Donaldson, Christopher

2016-06-01

Serpentinization of ultramafic rocks is widely recognized as a source of molecular hydrogen (H2) and methane (CH4) to support microbial activity, but the extent and rates of formation of these compounds in low-temperature, near-surface environments are poorly understood. Laboratory experiments were conducted to examine the production of H2 and CH4 during low-temperature reaction of water with ultramafic rocks and minerals. Experiments were performed by heating olivine or harzburgite with aqueous solutions at 90°C for up to 213 days in glass bottles sealed with butyl rubber stoppers. Although H2 and CH4 increased steadily throughout the experiments, the levels were very similar to those found in mineral-free controls, indicating that the rubber stoppers were the predominant source of these compounds. Levels of H2 above background were observed only during the first few days of reaction of harzburgite when CO2 was added to the headspace, with no detectable production of H2 or CH4 above background during further heating of the harzburgite or in experiments with other mineral reactants. Consequently, our results indicate that production of H2 and CH4 during low-temperature alteration of ultramafic rocks may be much more limited than some recent experimental studies have suggested. We also found no evidence to support a recent report suggesting that spinels in ultramafic rocks may stimulate H2 production. While secondary silicates were observed to precipitate during the experiments, formation of these deposits was dominated by Si released by dissolution of the glass bottles, and reaction of the primary silicate minerals appeared to be very limited. While use of glass bottles and rubber stoppers has become commonplace in experiments intended to study processes that occur during serpentinization of ultramafic rocks at low temperatures, the high levels of H2, CH4, and SiO2 released during heating indicate that these reactor materials are unsuitable for this purpose. Serpentinization-Hydrogen generation-Abiotic methane synthesis. Astrobiology 16, 389-406.

A review on the suitability of rubberized concrete for concrete bridge decks

NASA Astrophysics Data System (ADS)

Syamir Senin, Mohamad; Shahidan, Shahiron; Radziah Abdullah, Siti; Anting Guntor, Nickholas; Syazani Leman, Alif

2017-11-01

Road authorities manage a large population of ageing bridges, a substantial number of which fail to meet the current requirements either due to deterioration and other structural deficiencies or as a result of the escalating demands imposed by increased traffic. This problem is related to the dynamic load from vehicles. This problem can be solved by producing a type of concrete that can reduce the amplitude of oscillation or vibration such as rubberized concrete. Green construction has been a very important aspect in concrete production field in the last decade. One of the most problematic waste materials is scrap tires. The use of scrap tires in civil engineering is increasing by producing rubberized concrete. Rubberized concrete is a type of concrete that is mixed with rubber. The purpose of this review is to justify the suitability of rubberized concrete for concrete bridge decks. Several parameters named physical, chemical and mechanical properties were measured to ensure the suitability of rubberized concrete for concrete bridge decks. Rubberized concrete has similar workability to normal concrete. The rubber reduced the density and compressive strength of the concrete while increased the flexural strength, water absorption and damping ratio. The used of rubber in concrete beyond 20% is not recommended due to decreasing in compressive strength. Rubberized concrete recommended to be used in circumstances where vibration damping was required such as in bridge construction as shock-wave absorber.

Possibility of using waste tire rubber and fly ash with Portland cement as construction materials.

PubMed

Yilmaz, Arin; Degirmenci, Nurhayat

2009-05-01

The growing amount of waste rubber produced from used tires has resulted in an environmental problem. Recycling waste tires has been widely studied for the last 20 years in applications such as asphalt pavement, waterproofing systems and membrane liners. The aim of this study is to evaluate the feasibility of utilizing fly ash and rubber waste with Portland cement as a composite material for masonry applications. Class C fly ash and waste automobile tires in three different sizes were used with Portland cement. Compressive and flexural strength, dry unit weight and water absorption tests were performed on the composite specimens containing waste tire rubber. The compressive strength decreased by increasing the rubber content while increased by increasing the fly ash content for all curing periods. This trend is slightly influenced by particle size. For flexural strength, the specimens with waste tire rubber showed higher values than the control mix probably due to the effect of rubber fibers. The dry unit weight of all specimens decreased with increasing rubber content, which can be explained by the low specific gravity of rubber particles. Water absorption decreased slightly with the increase in rubber particles size. These composite materials containing 10% Portland cement, 70% and 60% fly ash and 20% and 30% tire rubber particles have sufficient strength for masonry applications.

Mechanical properties of concrete containing a high volume of tire-rubber particles.

PubMed

Khaloo, Ali R; Dehestani, M; Rahmatabadi, P

2008-12-01

Due to the increasingly serious environmental problems presented by waste tires, the feasibility of using elastic and flexible tire-rubber particles as aggregate in concrete is investigated in this study. Tire-rubber particles composed of tire chips, crumb rubber, and a combination of tire chips and crumb rubber, were used to replace mineral aggregates in concrete. These particles were used to replace 12.5%, 25%, 37.5%, and 50% of the total mineral aggregate's volume in concrete. Cylindrical shape concrete specimens 15 cm in diameter and 30 cm in height were fabricated and cured. The fresh rubberized concrete exhibited lower unit weight and acceptable workability compared to plain concrete. The results of a uniaxial compressive strain control test conducted on hardened concrete specimens indicate large reductions in the strength and tangential modulus of elasticity. A significant decrease in the brittle behavior of concrete with increasing rubber content is also demonstrated using nonlinearity indices. The maximum toughness index, indicating the post failure strength of concrete, occurs in concretes with 25% rubber content. Unlike plain concrete, the failure state in rubberized concrete occurs gently and uniformly, and does not cause any separation in the specimen. Crack width and its propagation velocity in rubberized concrete are lower than those of plain concrete. Ultrasonic analysis reveals large reductions in the ultrasonic modulus and high sound absorption for tire-rubber concrete.

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

2016-05-23

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.

Performance of USDA guayule lines in the Northern Negev of Israel

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

Mills, D.; Benzioni, A.; Forti, M.

The rubber yield of the guayule plant (Parthenium argentatum) is determined by its rubber concentration and biomass production, both of which are a function of genetic constituents and environmental conditions. With the aim of selecting best performing lines of guayule under the climatic conditions of the northern Negev of Israel, two-yr-old guayule plants from 13 USDA lines were evaluated for height, spread, canopy fresh and dry weight, branch and leaf dry weight, rubber and resin concentration, and rubber and resin yield per plant. Significant differences were found among the lines for all the characteristics tested. Lines 11600 and 11604 excelledmore » in rubber and biomass production and were taller and more uniform than the other lines; whereas line N593, conventionally used as a standard, performed poorly and was less uniform. The correlation between rubber yield per plant and rubber concentration was poor, rubber yield being related mainly to biomass production and to a lesser degree to height and spread of the plants. Taken together with fact that biomass production was more variable than rubber concentration, this finding suggests that breeding and selection of guayule and for high rubber yield should be directed primarily towards improvement of biomass production rather than rubber concentration. In the northern Negev of Israel, USDA lines 11600 and 11604 performed well.« less

40 CFR Table 5 to Subpart U of... - Known Organic HAP Emitted From the Production of Elastomer Products

Code of Federal Regulations, 2010 CFR

2010-07-01

...) ✔ Epichlorohydrin (106898) ✔ Ethylbenzene (100414) ✔ ✔ Ethylene Dichloride (107062) ✔ Ethylene Oxide (75218... Rubber. EPI = Epichlorohydrin Rubber. EPR = Ethylene Propylene Rubber. HBR = Halobutyl Rubber. HYP...

Kinetics of zinc release from ground tire rubber and rubber ash in a calcareous soil as alternatives to Zn fertilizers

USDA-ARS?s Scientific Manuscript database

Ground rubber contains 15-20 g Zn/kg but very low levels of Cd and could serve as an inexpensive byproduct Zn fertilizer. The aim of this investigation was to test the kinetics of Zn release in a soil treated with ground tire rubber and rubber ash compared with commercial Zn fertilizer and a labora...

Source Hierarchy List. Volume 2. E through N

DTIC Science & Technology

1994-07-01

SEE CONTINENTAL AG HANNOVER (GERMANY F R) 421628 02 GENERAL TIRE AND RUBBER CO MARION IN 151750 02 GENERAL TIRE ANO RUBBER CO WABASH IN...151800 03 GENERAL TIRE AND RUBBER CO WABASH IN 151820 INDUSTRIAL PRODUCTS DIV...GENERAL TIRE AND RUBBER CO WABASH IN 151800 FOR HIGHEST ORGANIZATIONAL LEVEL SEE CONTINENTAL AG HANNOVER (GERMANY F R) G3 GENERAL TIRE AND RUBBER CO

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, it has been found that cleaning of SBS rubber in an ultrasonic bath prior to plasma torch treatment produced a partial removal of paraffin waxes from the surface, and thus improved adhesion was obtained.

Detection of Interfacial Debonding in a Rubber-Steel-Layered Structure Using Active Sensing Enabled by Embedded Piezoceramic Transducers.

PubMed

Feng, Qian; Kong, Qingzhao; Jiang, Jian; Liang, Yabin; Song, Gangbing

2017-09-01

Rubber-steel-layered structures are used in many engineering applications. Laminated rubber-steel bearing, as a type of seismic isolation device, is one of the most important applications of the rubber-steel-layered structures. Interfacial debonding in rubber-steel-layered structures is a typical failure mode, which can severely reduce their load-bearing capacity. In this paper, the authors developed a simple but effective active sensing approach using embedded piezoceramic transducers to provide an in-situ detection of the interfacial debonding between the rubber layers and steel plates. A sandwiched rubber-steel-layered specimen, consisting of one rubber layer and two steel plates, was fabricated as the test specimen. A novel installation technique, which allows the piezoceramic transducers to be fully embedded into the steel plates without changing the geometry and the surface conditions of the plates, was also developed in this research. The active sensing approach, in which designed stress waves can propagate between a pair of the embedded piezoceramic transducers (one as an actuator and the other one as a sensor), was employed to detect the steel-rubber debonding. When the rubber-steel debonding occurs, the debonded interfaces will attenuate the propagating stress wave, so that the amplitude of the received signal will decrease. The rubber-steel debonding was generated by pulling the two steel plates in opposite directions in a material-testing machine. The changes of the received signal before and after the debonding were characterized in a time domain and further quantified by using a wavelet packet-based energy index. Experiments on the healthy rubber-steel-layered specimen reveal that the piezoceramic-induced stress wave can propagate through the rubber layer. The destructive test on the specimen demonstrates that the piezoceramic-based active sensing approach can effectively detect the rubber-steel debonding failure in real time. The active sensing approach is often used in structures with "hard" materials, such as steel, concrete, and carbon fiber composites. This research lays a foundation for extending the active sensing approach to damage detection of structures involving "soft" materials, such as rubber.

Addition of Rubber to soil damages the functional diversity of soil.

PubMed

Goswami, Madhurankhi; Bhattacharyya, Purnita; Tribedi, Prosun

2017-07-01

Rubber is a polymer of isoprene, consisting mainly of cis-1,4-polyisoprene units. The unmanageable production and its irresponsible disposal pose severe threats to environmental ecology. Therefore, the current study focuses extensively on the ill-effects of Rubber disposal on soil microbial functional diversity as it reflects the health of ecosystem by acting as a key component in ecosystem productivity. To investigate the effect of Rubber on soil microbial functional diversity, soil samples were collected from landfill sites and three different soil microcosms (Rubber treated, untreated, and sterile soil) were prepared. The soil enzymatic activity was determined by fluorescein diacetate hydrolysis followed by the determination of the microbial metabolic potential and functional diversity by average well color development and Shannon-Weaver index (H), respectively. BiOLOG ECO plates were used for determining the microbial functional diversity of the soil microcosms. Higher heterotrophic microbial count as well as higher soil microbial activity was observed in Rubber untreated soil than Rubber treated soil microcosm. The result indicated that the addition of Rubber to soil reduced soil heterotrophic microbial count and soil microbial activity considerably. Similarly, soil microbial metabolic potential as well as microbial functional diversity of soil had been decreased by the addition of Rubber gloves in it. Variation in soil microbial metabolic spectrum between Rubber treated and untreated microcosm was confirmed by multivariate analysis. Collectively, all the results demonstrated that the addition of Rubber to soil reduced the soil microbial functional diversity considerably. Therefore, it is necessary for the commission of serious steps regarding Rubber disposal and protection of the environment from serious environmental issues.

Z-Pin Stubble Technology Advanced Research (ZSTAR)

DTIC Science & Technology

2008-04-01

2.3 MANUFACTURING WITH RUBBER SHEETS ...................................................................... 12 2.3.1 Rubber Sheet Material...17 2.3.6 Rubber Material Intact and Gripped ........................................................................ 17 2.3.7 Successful...0.125 inch Stubble Fabrication ............................................................... 17 2.3.8 Rubber Material Guidelines

Characterization of Hexsyn, a polyolefin rubber.

PubMed

McMillin, C R

1987-07-01

Hexsyn is the Goodyear Tire and Rubber Company tradename for a polyolefin rubber synthesized from 1-hexene with 3-5% methylhexadiene as the source of residual double bonds for vulcanization. Under license from Goodyear, this same polymer has been manufactured by Lord Corporation for the hinge portion of finger joint prostheses using the tradename Bion. This rubber is currently licensed to the University of Akron and to the Cleveland Clinic Foundation for use in biomedical applications, and is being used primarily for biocompatible and highly fatigue resistant rubber components in ventricular assist and artificial heart systems. Results are presented from the physical, mechanical, and biological characterization of Hexsyn. Procedures are described for the synthesis, compounding, and post-molding extraction for Hexsyn. The physical testing of Hexsyn reported includes determinations of its density at 23 and 37 degrees C, initial hardness and hardness after aging in oxygen, blood, pseudoextracellular fluid and polyethylene glycol 600, typical molecular weights determined by gel permeation chromatography/low angle laser light scattering and intrinsic viscosity, thermal analyses by differential scanning calorimetry of Hexsyn gum, and vulcanized Hexsyn after exposure to blood and blood/fatigue conditions. Also reported are results of differential thermal analyses, thermomechanical analyses of virgin and annealed samples, and thermogravimetric analyses conducted in helium and in air. Dynamic mechanical analyses of Hexsyn include Clash-Berg and Rheovibron tests. Swelling was conducted to determine lot-to-lot and sheet-to-sheet variation for quality control and also a number of solvents were used so that the polymer-solvent interaction parameters could be determined. The permeability of Hexsyn to water, water vapor, and a variety of gases is reported. The permeability by contact angle measurements, refractive index, residual solvent analyses, migration of blood components into Hexsyn, melt rheology by Monsanto Rheometer, resistance to acids, and typical mold shrinkage for Hexsyn are reported. Mechanical testing of Hexsyn includes tensile strength, elongation, and tensile stress (modulus) at 23 and 37 degrees C and after conditions including exposure to blood, pseudoextracellular fluid, polyethylene glycol, oxygen, 100% relative humidity, and fatigue testing. Stress/strain calibration curves, flexural rigidity after aging in blood, tension set, compression set, stress relaxation, and the effect of repeated cycling on the elastic modulus are presented along with the results of Pico abrasion, skid resistance tests on wet concrete.(ABSTRACT TRUNCATED AT 400 WORDS)

The reclaiming of butyl rubber and in-situ compatibilization of thermoplastic elastomer by power ultrasound

NASA Astrophysics Data System (ADS)

Feng, Wenlai

This is a study of the continuous ultrasound aided extrusion process for the in-situ compatibilization of isotactic polypropylene (iPP)/ethylene-propylene diene rubber (EPDM) thermoplastic elastomer (TPE) using a newly developed ultrasonic treatment reactor. The rheological, mechanical properties and morphology of the TPE with and without ultrasonic treatment were studied. In-situ compatibilization in the ultrasonically treated blends was observed as evident by their more stable morphology after annealing, improved mechanical properties and IR spectra. The obtained results indicated that ultrasonic treatment induced the thermo-mechanical degradations and led to the possibility of enhanced molecular transport and chemical reactions at the interfaces. Processing conditions were established for enhanced in situ compatibilization of the PP/EPDM TPE. The ultrasonic treatments of butyl rubber gum and ultrasonic devulcanization of butyl rubber, tire-curing bladder during extrusion using a grooved barrel ultrasonic reactor were carried out. The ultrasonic treatment of gum caused degradation of the polymer main chain leading to lower molecular weight, broader molecular weight distribution, less unsaturation and changes in physical properties. The devulcanization of butyl rubber was successfully accomplished only at severe conditions of ultrasonic treatment. The mechanical properties of vulcanizates prepared from devulcanized butyl rubber are comparable to that of the virgin vulcanizate. The molecular characterization of sol fraction of devulcanized butyl rubber showed the devulcanization and degradation of butyl rubber occurred simultaneously. 1H NMR transverse relaxation was also used to study butyl rubber gum before and after ultrasonic treatment, and ultrasonically devulcanized unfilled butyl rubber. The T2 relaxation decays were successfully described using a two-component model. The recyclability of tire-curing bladder was also investigated. Gel fraction, crosslink density, cure behavior, dynamic properties and mechanical properties were measured. Good mechanical properties of revulcanized rubber were achieved by blending devulcanized rubber with the carbon black filled virgin butyl rubber. The structural characteristics of devulcanized butyl rubber were simulated using the Dobson-Gordon theory of rubber network statistics. A fairly good agreement between experimental data and theoretical prediction on normalized gel fraction vs. normalized crosslink density was achieved. The simulation of devulcanized butyl rubber indicated that the rate of crosslink rupture is much higher than that of the main chain.

Effect of vulcanization temperature and humidity on the properties of RTV silicone rubber

NASA Astrophysics Data System (ADS)

Wu, Xutao; Li, Xiuguang; Hao, Lu; Wen, Xishan; Lan, Lei; Yuan, Xiaoqing; Zhang, Qingping

2017-06-01

In order to study the difference in performance of room temperature vulcanized (RTV) silicone rubber in vulcanization environment with different temperature and humidity, static contact angle method, FTIR and TG is utilized to depict the properties of hydrophobicity, transfer of hydrophobicity, functional groups and thermal stability of RTV silicone rubber. It is found that different vulcanization conditions have effects on the characteristics of RTV silicone rubber, which shows that the hydrophobicity of RTV silicone rubber changes little with the vulcanization temperature but a slight increase with the vulcanization humidity. Temperature and humidity have obvious effects on the hydrophobicity transfer ability of RTV silicone rubber, which is better when vulcanization temperature is 5°C or vulcanization humidity is 95%. From the Fourier transform infrared spectroscopy, it can be concluded that humidity and temperature of vulcanization conditions have great effect on the functional groups of silicone rubber, and vulcanization conditions also have effect on thermal stability of RTV silicone rubber. When vulcanization temperature is 5°C or vulcanization humidity is 15% or 95%, the thermal stability of silicone rubber becomes worse.

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 applications such as additives to waterborne emulsions. This innovative process for the first time opened up the application of rubber particles in aqueous media. The kinetics of polymerization reaction of hydrophilic monomer mixture within the rubber particles was investigated based on the assumption of partitioning of acrylic acid monomer in the hydrophobic rubber particles. The produced PPSIPNs were used as additives to waterborne emulsions and the mechanical and physical properties of the prepared coatings were examined. It was observed that the PPSIPNs could be added in high quantities with an improvement in adhesion, enhancement of the impact strength, and hardness of the coatings. This approach aims to develop environmentally benign products from scrap rubber materials.

Gamma irradiation induced effects of butyl rubber based damping material

NASA Astrophysics Data System (ADS)

Chen, Hong-Bing; Wang, Pu-Cheng; Liu, Bo; Zhang, Feng-Shun; Ao, Yin-Yong

2018-04-01

The effects of gamma irradiation on the butyl rubber based damping material (BRP) at various doses in nitrogen were investigated in this study. The results show that irradiation leads to radiolysis of BRP, with extractives increasing from 14.9 ± 0.8% of control to 37.2 ± 1.2% of sample irradiated at 350 kGy, while the swelling ratio increasing from 294 ± 3% to 766 ± 4%. The further investigation of the extractives with FTIR shows that the newly generated extractives are organic compounds containing C-H and C˭C bonds, with molecular weight ranging from 26,500 to 46,300. SEM characterization shows smoother surface with holes disappearing with increasing absorbed doses, consistent with "softer" material because of radiolysis. Dynamic mechanical study of BRP show that tan δ first slightly then obviously increases with increasing absorbed dose, while storage modulus slightly decreases. The tensile testing shows that the tensile strength decreases while the elongation at break increases with increasing dose. The positron annihilation lifetime spectroscopy show no obvious relations between free volume parameters and the damping properties, indicating the complicated influencing factors of damping properties.

Synthesis of a novel hydantoin-containing silane and its effect on the tracking and bacteria resistance of addition-cure liquid silicone rubber

NASA Astrophysics Data System (ADS)

Liu, Tian; Zeng, Xingrong; Fang, Weizhen; Lai, Xuejun; Li, Hongqiang

2017-11-01

A novel hydantoin-containing silane, [3-(5,5-dimethylhydantoinurethano) propyl] ethoxyallyloxysilane (DMHURPAS), was synthesized and the structure was characterized by FTIR and 1H NMR. The effect of DMHURPAS was investigated on the anti-tracking and antibacterial properties of addition-cure liquid silicone rubber (ALSR) after surface chlorination. It was found that ALSR containing only 1.5 phr of DMHURPAS passed 1A 4.5 kV level and erosion mass decreased from 0.843 g to 0.037 g. The thermal stability of ALSR was significantly improved and the mechanical properties were also enhanced. From thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR), ALSR/DMHURPAS showed significant decrease of carbonyl compounds and cyclic oligomers but increase of CH4 and CO2 during thermal degradation, indicating that DMHURPAS could inhibit oxidation of methyl groups and unzipping reaction, and promote the cleavage of methyl groups in ALSR. The antibacterial rates of ALSR containing 2.0 phr of DMHURPAS against Escherichia coli and Staphylococcus aureus were 95.7% and 83.4%, respectively.

Effect of torrefaction pretreatment on the pyrolysis of rubber wood sawdust analyzed by Py-GC/MS.

PubMed

Chen, Wei-Hsin; Wang, Chao-Wen; Kumar, Gopalakrishnan; Rousset, Patrick; Hsieh, Tzu-Hsien

2018-07-01

The aim of this study was to investigate the effect of torrefaction on the pyrolysis of rubber wood sawdust (RWS) using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Three typical torrefaction temperatures (200, 250, and 300 °C) and pyrolysis temperatures (450, 500, and 550 °C) were considered. The results suggested that only diethyl phthalate, belonging to esters, was detected at the torrefaction temperatures of 200 and 250 °C, revealing hemicellulose degradation. With the torrefaction temperature of 300 °C, esters, aldehydes, and phenols were detected, suggesting the predominant decomposition of hemicellulose and lignin. The double-shot pyrolysis indicated that the contents of oxy-compounds such as acids and aldehydes in pyrolysis bio-oil decreased with rising torrefaction temperature, implying that increasing torrefaction severity abated oxygen content in the bio-oil. With the torrefaction temperature of 300 °C, relatively more cellulose was retained in the biomass because the carbohydrate content in the pyrolysis bio-oil increased significantly. Copyright © 2018 Elsevier Ltd. All rights reserved.

Laboratory testing the Anaconda.

PubMed

Chaplin, J R; Heller, V; Farley, F J M; Hearn, G E; Rainey, R C T

2012-01-28

Laboratory measurements of the performance of the Anaconda are presented, a wave energy converter comprising a submerged water-filled distensible tube aligned with the incident waves. Experiments were carried out at a scale of around 1:25 with a 250 mm diameter and 7 m long tube, constructed of rubber and fabric, terminating in a linear power take-off of adjustable impedance. The paper presents some basic theory that leads to predictions of distensibility and bulge wave speed in a pressurized compound rubber and fabric tube, including the effects of inelastic sectors in the circumference, longitudinal tension and the surrounding fluid. Results are shown to agree closely with measurements in still water. The theory is developed further to provide a model for the propagation of bulges and power conversion in the Anaconda. In the presence of external water waves, the theory identifies three distinct internal wave components and provides theoretical estimates of power capture. For the first time, these and other predictions of the behaviour of the Anaconda, a device unlike almost all other marine systems, are shown to be in remarkably close agreement with measurements.

Graphite intercalation compound with iodine as the major intercalant

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh; Kucera, Donald

1992-01-01

Halogenated CBr(sub x)I(sub y) (1 less than y/x less than 10) was made by exposing graphite materials with interplanar spacing in the 3.35 to 3.41 A range to either pure Br2 or an I2-Br2 mixture, and then to iodine vapor containing a small amount of Br2. The electrical resistivity of this product is from 3 to 6.5 times the pristine value. The presence of a small amount of isoprene rubber in the reaction significantly increased the iodine to bromine ratio in the product. In this reaction, rubber is known to generate HBr and to slowly remove bromine from the vapor. The halogenation generally caused a 22 to 25 percent weight increase. The halogens were found uniformly distributed in the product interior. However, although the surface contains very little iodine, it has high concentrations of bromine and oxygen. It is believed that the high concentrations of bromine and oxygen in this surface cause the halogenated fiber to be more resistant to fluorine attack during subsequent fluorination to fabricate graphite fluoride fibers.

Characterization of asphalt cements modified with crumbed rubber from discarded tires : final report.

DOT National Transportation Integrated Search

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. Blend...

Investigation to Identify Performance Criteria and Test Methods for Evaluating Single-Ply Roofing Systems.

DTIC Science & Technology

1987-03-01

Reinforced Black EPDM Rubber Sheets for Use in Roofing Applications ( Rubber Manufacturers Association [RMAJ, 1984). Minimum Requirements for Fabric-Reinforced...Black Polychloroprene Rubber Sheets for Use in Roofing Applications (RMA, 1984). Minimum Requirements for Non-Reinforced Black EPDM Rubber Sheets for...and materials. The Rubber Manufacturers Amoeiation (RMA) (USA) RMA is funding a study in conjunction with ASTM to evaluate three different EPDM

The use of smoke acid as an alternative coagulating agent for natural rubber sheets' production.

PubMed

Ferreira, Vanda S; Rêgo, Ione N C; Pastore, Floriano; Mandai, Mariana M; Mendes, Leonardo S; Santos, Karin A M; Rubim, Joel C; Suarez, Paulo A Z

2005-03-01

A comparative study of rubber sheets obtained using formic, acetic, and smoke acid as coagulants is shown for latex obtained from native Amazonian trees and also from commercial cultivated trees. The evaluation of both processes of coagulation was carried out by spectroscopic and physical-chemical analysis, showing no differences in the rubber sheets obtained. This new method of rubber sheet preparation was introduced into Amazonian rainforest rubber tapper communities, which are actually producing in large scale. The physical-mechanical properties were similar among a large sheets made by different rubber tapper communities using this new method.

FTIR spectra and mechanical strength analysis of some selected rubber derivatives.

PubMed

Gunasekaran, S; Natarajan, R K; Kala, A

2007-10-01

Rubber materials have wide range of commercial applications such as, infant diapers, famine hygiene products, drug delivery devices and incontinency products such as rubber tubes, tyres, etc. In the present work, studies on mechanical properties of some selected rubber materials viz., natural rubber (NR), styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR) and ethylene propylene diene monomer (EPDM) have been carried out in three states viz., raw, vulcanized and reinforced. To enhance the quality of rubber elastomers, an attempt is made to prepare new elastomers called polyblends. In the present study an attempt is made to blend NR with NBR and with EPDM. We here report, a novel approach for the evaluation of various physico-mechanical properties such as mechanical strength, tensile strength, elongation and hardness. The method is simple, direct and fast and involves infrared spectral measurements for the evaluation of these properties. With the applications of modern infrared spectroscopy, the mechanical strength of these rubber materials have been analyzed by calculating the internal standards among the methyl and methylene group vibrational frequencies obtained from FTIR spectroscopy. Also the tensile strength measurements carried out by universal testing machine. The results pertaining physico-mechanical properties of the rubber derivatives undertaken in the present study obtained by IR-based method are in good agreement with data resulted from the standard methods.

FTIR spectra and mechanical strength analysis of some selected rubber derivatives

NASA Astrophysics Data System (ADS)

Gunasekaran, S.; Natarajan, R. K.; Kala, A.

2007-10-01

Rubber materials have wide range of commercial applications such as, infant diapers, famine hygiene products, drug delivery devices and incontinency products such as rubber tubes, tyres, etc. In the present work, studies on mechanical properties of some selected rubber materials viz., natural rubber (NR), styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR) and ethylene propylene diene monomer (EPDM) have been carried out in three states viz., raw, vulcanized and reinforced. To enhance the quality of rubber elastomers, an attempt is made to prepare new elastomers called polyblends. In the present study an attempt is made to blend NR with NBR and with EPDM. We here report, a novel approach for the evaluation of various physico-mechanical properties such as mechanical strength, tensile strength, elongation and hardness. The method is simple, direct and fast and involves infrared spectral measurements for the evaluation of these properties. With the applications of modern infrared spectroscopy, the mechanical strength of these rubber materials have been analyzed by calculating the internal standards among the methyl and methylene group vibrational frequencies obtained from FTIR spectroscopy. Also the tensile strength measurements carried out by universal testing machine. The results pertaining physico-mechanical properties of the rubber derivatives undertaken in the present study obtained by IR-based method are in good agreement with data resulted from the standard methods.

The outgassing characteristic research of the silicone rubber in high power laser system

NASA Astrophysics Data System (ADS)

Wu, Qipeng; Lv, Haibing; Dong, Meng; Fu, Zhaohui

2016-11-01

The outgassing characteristic of the silicone rubber which is the main material of non-metallic materials in high power laser system was studied outgassing rates of the silicone rubber and the baked-out silicone rubber which was performed at 80°C4 hours were measured by the constant volume process method and outgassing properties of them were analyzed by the quadrupole mass spectrometer. The results show that the outgassing rate of the silicone rubber and the baked-out silicone rubber is 2.69×10-7 Pa·m3s-1cm-2 and 6.47×10-8 Pa·m3s-1cm-2 respectively. All of them give out condensable volatile matter in vacuum. The outgassing rate and condensable volatile matter of the baked-out silicone rubber are less an order of magnitude compared with the silicone rubber, and the outgassing rate of the silicone rubber is less than 1×10-7 Pa·m3s-1cm-2, which is fit for non-metallic material of the high power laser system. This paper also discusses the method of reducing the outgassing rate and condensable volatile matter of the silicone rubber in high power laser system.

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

2015-09-08

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.

RoxB Is a Novel Type of Rubber Oxygenase That Combines Properties of Rubber Oxygenase RoxA and Latex Clearing Protein (Lcp).

PubMed

Birke, Jakob; Röther, Wolf; Jendrossek, Dieter

2017-07-15

Only two types of rubber oxygenases, rubber oxygenase (RoxA) and latex clearing protein (Lcp), have been described so far. RoxA proteins (RoxAs) are c -type cytochromes of ≈70 kDa produced by Gram-negative rubber-degrading bacteria, and they cleave polyisoprene into 12-oxo-4,8-dimethyltrideca-4,8-diene-1-al (ODTD), a C 15 oligo-isoprenoid, as the major end product. Lcps are common among Gram-positive rubber degraders and do not share amino acid sequence similarities with RoxAs. Furthermore, Lcps have much smaller molecular masses (≈40 kDa), are b -type cytochromes, and cleave polyisoprene to a mixture of C 20 , C 25 , C 30 , and higher oligo-isoprenoids as end products. In this article, we purified a new type of rubber oxygenase, RoxB Xsp (RoxB of Xanthomonas sp. strain 35Y). RoxB Xsp is distantly related to RoxAs and resembles RoxAs with respect to molecular mass (70.3 kDa for mature protein) and cofactor content (2 c -type hemes). However, RoxB Xsp differs from all currently known RoxAs in having a distinctive product spectrum of C 20 , C 25 , C 30 , and higher oligo-isoprenoids that has been observed only for Lcps so far. Purified RoxB Xsp revealed the highest specific activity of 4.5 U/mg (at 23°C) of all currently known rubber oxygenases and exerts a synergistic effect on the efficiency of polyisoprene cleavage by RoxA Xsp RoxB homologs were identified in several other Gram-negative rubber-degrading species, pointing to a prominent function of RoxB for the biodegradation of rubber in Gram-negative bacteria. IMPORTANCE The enzymatic cleavage of rubber (polyisoprene) is of high environmental importance given that enormous amounts of rubber waste materials are permanently released (e.g., by abrasion of tires). Research from the last decade has discovered rubber oxygenase A, RoxA, and latex clearing protein (Lcp) as being responsible for the primary enzymatic attack on the hydrophobic and water-insoluble biopolymer poly( cis -1,4-isoprene) in Gram-negative and Gram-positive rubber-degrading bacteria, respectively. Here, we provide evidence that a third type of rubber oxygenase is present in Gram-negative rubber-degrading species. Due to its characteristics, we suggest the designation RoxB for the new type of rubber oxygenase. Bioinformatic analysis of genome sequences indicates the presence of roxB homologs in other Gram-negative rubber degraders. Copyright © 2017 American Society for Microbiology.

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, thus helping to understand the dynamics of the rubber tree resource. The decrease in the area of rubber plantations and the increase in the area of mixed crops from 1989--1993 in south of KL were partly attributed to the adoption of a crop diversification policy which was driven by relatively poor natural rubber prices during that time. The decrease in the areas of rubber plantations from 1993--1999 in this area was primarily due to rapid urbanization and infrastructure development driven by demographic expansion in the area south of KL. This thesis makes a practical contribution to the development of methods for inventory of forest plantations by linking ground information with model projections based on satellite data. Additionally, the thesis demonstrates the development of monitoring tools to assess resource availability and variability over time, and establish its linkages to policies. The inventory information, models, and monitoring protocols are needed for effective resource management planning aimed at maximizing the potential benefits of rubber tree crops for wood and natural rubber supply in Malaysia.

Mutagens in urine of non-smoking and smoking workers in an aircraft tyre retreading plant. Skin exposure as a causal factor?

PubMed

Bos, R P; Kromhout, H; Ikink, H; de Haan, W; Koppejan, J; Theuws, J L

1989-05-01

In an aircraft type retreading plant environmental samples taken at several departments showed mutagenic properties. Thursday urine samples of non-smoking and smoking workers showed higher urinary mutagenicity than urine samples collected on Sundays, thus suggesting occupational exposure to mutagenic substances. A relation between urinary mutagenicity on Thursdays and skin contamination measured on Wednesdays was observed. The data suggest that intake through the skin plays an important role in the occupational exposure to mutagenic compounds of rubber workers.

Air Vehicle Integration and Technology Research (AVIATR). Delivery Order 0002: Condition-Based Maintenance Plus Structural Integrity (CBM+SI) Strategy Development

DTIC Science & Technology

2010-11-01

material. The rubber is laser -etched with rows of tiny, interconnected channels or galleries, to which air pressure is applied. Any propagating crack... clad one side. The Upper Lobe has a radius of approximately 85” (compound curvature) in the region of interest. As stated previously, the skin is...7079-T6 sheet; clad one side with a varying thickness of 0.050” to 0.071” (varies according to stability requirements for compression combined with

Abscisic acid-dependent regulation of small rubber particle protein gene expression in Taraxacum brevicorniculatum is mediated by TbbZIP1.

PubMed

Fricke, Julia; Hillebrand, Andrea; Twyman, Richard M; Prüfer, Dirk; Schulze Gronover, Christian

2013-04-01

Natural rubber is a high-molecular-mass biopolymer found in the latex of >2,500 plant species, including Hevea brasiliensis, Parthenium argentatum and Taraxacum spp. The active sites of rubber biosynthesis are rubber particles, which comprise a hydrophobic rubber core surrounded by a phospholipid monolayer membrane containing species-dependent lipids and associated proteins. Small rubber particle proteins are the most abundant rubber particle-associated proteins in Taraxacum brevicorniculatum (TbSRPPs) and may promote rubber biosynthesis by stabilizing the rubber particle architecture. We investigated the transcriptional regulation of genes encoding SRPPs and identified a bZIP transcription factor (TbbZIP.1) similar to the Arabidopsis thaliana ABI5-ABF-AREB subfamily, which is thought to include downstream targets of ABA and/or abiotic stress-inducible protein kinases. The TbbZIP.1 gene was predominantly expressed in laticifers and regulates the expression of TbSRPP genes in an ABA-dependent manner. The individual TbSRPP genes showed distinct induction profiles, suggesting diverse roles in rubber biosynthesis and stress adaptation. The potential involvement of TbSRPPs in the adaptation of T. brevicorniculatum plants to environmental stress is discussed based on our current knowledge of the stress-response roles of SRPPs and their homologs, and the protective function of latex and rubber against pathogens. Our data suggest that TbSRPPs contribute to stress tolerance in T. brevicorniculatum and that their effects are mediated by TbbZIP.1.

Methacrylamide grafted elastomer composites reinforced with biobased particles

USDA-ARS?s Scientific Manuscript database

Modulus of rubber can be improved with grafting of unsaturated monomers. To increase the modulus of bio-based rubber composites, methacrylamide was grafted onto natural rubber composites reinforced with bio-based hydrophilic particles. Rubber particles in water were modified with methacrylamide usin...

Interaggregate Interaction in Filled Rubber

DTIC Science & Technology

1989-01-01

from a black masterbatch (Carbomix 1848 from the Copolymer Rubber and Chemical Corporation). The masterbatch was unmilled (SBR-83-0), passed 5 times...Vanderbilt Company) 3 97% 1,2-polybutadiene (Firestone Tire and Rubber Company) 4 Carbomix 1848 Masterbatch (Copolymer Rubber and Chemical Corporation) 14

75 FR 38119 - Polychloroprene Rubber From Japan

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-01

... Rubber From Japan AGENCY: United States International Trade Commission. ACTION: Institution of a five-year review concerning the antidumping duty finding on polychloroprene rubber from Japan. SUMMARY: The... on polychloroprene rubber from Japan would be likely to lead to continuation or recurrence of...

Use of scrap tire rubber : state of the technology and best practices.

DOT National Transportation Integrated Search

2005-02-01

The California Department of Transportation (Caltrans) has been using scrap tire rubber (called crumb : rubber modifier (CRM)) in asphalt pavements since the 1970s in chip seals and the 1980s in rubberized : asphalt concrete (RAC). The performance of...

Slipping through the Cracks: Rubber Plantation Is Unsuitable Breeding Habitat for Frogs in Xishuangbanna, China

PubMed Central

Behm, Jocelyn E.; Yang, Xiaodong; Chen, Jin

2013-01-01

Conversion of tropical forests into agriculture may present a serious risk to amphibian diversity if amphibians are not able to use agricultural areas as habitat. Recently, in Xishuangbanna Prefecture, Yunnan Province – a hotspot of frog diversity within China – two-thirds of the native tropical rainforests have been converted into rubber plantation agriculture. We conducted surveys and experiments to quantify habitat use for breeding and non-breeding life history activities of the native frog species in rainforest, rubber plantation and other human impacted sites. Rubber plantation sites had the lowest species richness in our non-breeding habitat surveys and no species used rubber plantation sites as breeding habitat. The absence of breeding was likely not due to intrinsic properties of the rubber plantation pools, as our experiments indicated that rubber plantation pools were suitable for tadpole growth and development. Rather, the absence of breeding in the rubber plantation was likely due to a misalignment of breeding and non-breeding habitat preferences. Analyses of our breeding surveys showed that percent canopy cover over pools was the strongest environmental variable influencing breeding site selection, with species exhibiting preferences for pools under both high and low canopy cover. Although rubber plantation pools had high canopy cover, the only species that bred in high canopy cover sites used the rainforest for both non-breeding and breeding activities, completing their entire life cycle in the rainforest. Conversely, the species that did use the rubber plantation for non-breeding habitat preferred to breed in low canopy sites, also avoiding breeding in the rubber plantation. Rubber plantations are likely an intermediate habitat type that ‘slips through the cracks’ of species habitat preferences and is thus avoided for breeding. In summary, unlike the rainforests they replaced, rubber plantations alone may not be able to support frog populations. PMID:24040026

[Contemporary state of work conditions and occupational morbidity of workers engaged into rubber, mechanical rubber and tire industries].

PubMed

Stepanov, E G; Galiullina, É F; Samsonov, V M; Kudriavtsev, V P; Davletgareeva, G R; Shakirova, É D; Khasanov, B G; Buliakov, R T; Kamilov, R F; Shakirov, D F

2014-01-01

Based on analysis of materials provided by occupational safety department PC "UZEMiK" and JSC "Kauchuk", the authors evaluate contemporary work conditions and occupational morbidity in workers engaged into rubber, mechanical rubber and tyre industries.

Enhancing and standardizing interaction of rubber particles with asphalt : final report.

DOT National Transportation Integrated Search

1995-11-01

Addition of ground rubber particles to asphalt can enhance several fold the stiffness of the blend as reflected by G*/sin of the rubber-asphalt cements (RACs). Pretreatment of rubber particles with as little as 5% aromatic oil (AO) enhances the ap...

Magnesium affects rubber biosynthesis and particle stability in Ficus elastica, Hevea brasiliensis and Parthenium argentatum

USDA-ARS?s Scientific Manuscript database

Natural rubber biosynthesis occurs in laticifers of Ficus elastica and Hevea brasiliensis, and in parenchyma cells of Parthenium argentatum. Natural rubber is synthesized by rubber transferase using allylic pyrophosphates as initiators, isopentenyl pyrophosphate as monomeric substrate and magnesium ...

Audit Technical of Kori Rubber Dam in the River of Keyang District of Ponorogo East Java Province

NASA Astrophysics Data System (ADS)

Murnianto, E.; Suprapto, M.; Ikhsan, C.

2018-03-01

The development of science and technology for the utilization and protection of rivers has embodied various types of river infrastructure. Without proper maintenance, rapid river sediments undergo physical degradation and function. Problems that occur in Kori Rubber Dam, among others, the damage to the body of the rubber dam that is made of rubber, so that the function of flower deflection is not optimal. This happens because of limited operational and maintenance activities (OM). A technical audit is a process of identifying problems, analyzing, and evaluating ones conducted independently, objectively and professionally on the basis of examination, to assess the truth, accuracy, credibility, and reliability of information about a job. In this case an assessment of the Kori Rubber Dam, which is basically a benchmarking activity. Assessment of rubber dam components includes the physical conditions and functions that affect the weir. This research is expected to know the performance of Kori rubber Dam as a recommendation material in the implementation of OM Rubber Dam activities.

The use of gamma irradiation in preparation of polybutadiene rubber nanopowder; Its effect on particle size, morphology and crosslink structure of the powder

NASA Astrophysics Data System (ADS)

Rezaei Abadchi, Majid; Jalali-Arani, Azam

2014-02-01

The aim of this work was the preparation and characterization of polybutadiene rubber (BR) powder by irradiating of rubber lattices using 60Co radiation and spray-drying of them at the appropriate condition. The influences of absorbed dose on the volume swelling ratio, molecular weight between crosslinks, gel fraction, and glass transition temperature of obtained powder were studied. Morphology, size and size distribution of rubber particles were examined by using scanning electron microscopy (SEM) and laser particle size analyzer (LPSA) technique, respectively. Results obtained by LPSA revealed that radiation has no effect on particle size of rubber latex but after drying, adherence properties of rubber particle causes increase in particle size of rubber powder, as shown in SEM photograph. Fourier transform infrared spectroscopy of rubber powders confirmed that with increasing the irradiation dose, characteristic peak corresponds to the >Cdbnd C< double bands decreased. Also Charlesby-Pinner equation was used to evaluate radiation yield.

Analysis of Physical Properties and Mineralogical of Pyrolysis Tires Rubber Ash Compared Natural Sand in Concrete material

NASA Astrophysics Data System (ADS)

Syamir Senin, Mohamad; Shahidan, Shahiron; Syazani Leman, Alif; Izzati Raihan Ramzi Hannan, Nurul

2016-11-01

Waste tires pose significant health and environmental concerns if not recycled or discarded properly. At the same time, natural sand is becoming scarcer and costlier due to its non-availability. Waste tires as fine aggregate can be an economical and sustainable alternative to the natural sand. Recent years, the interest on recycling waste tires into civil engineering applications by the researchers has increased. In this research, the chemical and physical properties of the tires rubber ash and the natural sand have been analysed. The densities of the rubber ash are lower than the natural sand. Rubber ash had finer particle size compared to the natural sand. Almost all chemical in the natural sand had in rubber ash with the additional sulphur trioxide and zinc oxide in the rubber ash, made the rubber ash better than natural sand. Rubber ash seems to be a suitable material to use in concrete as sand replacement.

Practical application of thermoreversibly Cross-linked rubber products

NASA Astrophysics Data System (ADS)

Polgar, L. M.; Picchioni, F.; de Ruiter, E.; van Duin, M.

2017-07-01

Currently, rubber products cannot simply be reprocessed after their product life, due to the irreversible cross-linking methods traditionally applied. The purpose of this work is to investigate how thermoreversible cross-linking of rubbers via Diels Alder chemistry can be used for the development of recyclable rubber products. Unfortunately, the applicability of the thermoreversible EPM-g-furan/BM system appears to be limited to room temperature applications, because of the rapid deterioration of the compression set at elevated temperatures compared to irreversibly cross-linked EPM. However, the use of EPM rubber modified with thiophene or cyclopentadiene moieties may extend the temperature application range and results in rubber products with acceptable properties. Finally, rubber products generally comprise fillers such as silica, carbon black or fibers. In this context, the reinforcing effect of short cut aramid fibers on the material properties of the newly developed thermoreversibly cross-linked EPM rubbers was also studied. The material properties of the resulting products were found to be comparable to those of a fiber reinforced, peroxide cured reference sample.

Evaluation of rice husk ash as filler in tread compounds

NASA Astrophysics Data System (ADS)

Fernandes, M. R. S.; Furtado, C. R. G.; de Sousa, A. M. F.

2014-05-01

Rice which is one of the largest agriculture crops produces around 22% of rice rusk during its milling process. This material is mainly used as fuel for energy generation, which results in an ash, which disposal represents an environmental issue. The rice husk ash (RHA) contains over than 70% of silica in an amorphous form and a lot of applications is being developed for it all over the world. The use of silica as a filler in the tire industry is growing since it contributes significantly to the reduction of fuel consumption of the automobiles, allowing at the same time better traction (safety). This paper presents an evaluation of the use of RHA as filler in rubber tread compounds prepared in lab scale and compares its performance with compounds prepared with commercial silica and carbon black, the fillers normally used in tire industry. Mechanical and rheological properties are evaluated, with emphasis for tan delta as an indicator of tread performance related with rolling resistance (fuel consumption) and wet grip/traction (safety).

New type of liquid rubber and compositions based on it.

PubMed

Semikolenov, S V; Nartova, A V; Voronchikhin, V D; Dubkov, K A

2014-11-01

The new method for producing the functionalized polymers and oligomers containing carbonyl C=O groups is developed. The method is based on the noncatalytic oxidation of unsaturated rubbers by nitrous oxide (N2O) at 180-230 °С. The proposed method allows obtaining the new type of functionalized rubbers-liquid unsaturated polyketones with regulated molecular weight and concentration of C=O groups. The influence of the liquid polyketone addition on properties of rubber-based composites is investigated. The study indicates good prospects of using the liquid polyketones for the improvement of properties and operating characteristics of the various types of rubbers and the rubber-cord systems.

Use of rubber crumbs in cement concrete

NASA Astrophysics Data System (ADS)

Longvinenko, A. A.

2018-03-01

Rubber crumb obtained from worn out tires has been increasingly used over the last 15-20 years, especially in manufacture of asphalt and cement concrete mixtures. This review pays principal attention to application of the rubber crumb to cement concrete mixtures. Use of the rubber crumb in cement concrete is not as successful as in asphalt concrete mixtures, due to incompatibility problems linked to chemical composition and a significant difference in rigidity between the rubber crumb and concrete mixture aggregates. Different methods are proposed and studied to mitigate the adverse influence and increase the beneficial effects of the rubber crumb when added to cement concrete.

Control Systems of Rubber Dryer Machinery Components Using Programmable Logic Control (PLC)

NASA Astrophysics Data System (ADS)

Hendra; Yulianto, A. S.; Indriani, A.; Hernadewita; Hermiyetti

2018-02-01

Application of programmable logic control (PLC) is widely used on the control systems in the many field engineering such as automotive, aviation, food processing and other industries [1-2]. PLC is simply program to control many automatic activity, easy to use, flexible and others. PLC using the ladder program to solve and regulated the control system component. In previous research, PLC was used for control system of rotary dryer machine. In this paper PLC are used for control system of motion component in the rubber dryer machinery. Component of rubber dryer machine is motors, gearbox, sprocket, heater, drying chamber and bearing. Principle working of rubber dryer machinery is wet rubber moving into the drying chamber by sprocket. Sprocket is driven by motors that conducted by PLC to moving and set of wet rubber on the drying chamber. Drying system uses greenhouse effect by making hanger dryer design in the form of line path. In this paper focused on motion control system motors and sensors drying rubber using PLC. The results show that control system of rubber dryer machinery can work in accordance control input and the time required to dry the rubber.

Efficacy of tray adhesives for the adhesion of elastomer rubber impression materials to impression modeling plastics for border molding.

PubMed

Nishigawa, G; Sato, T; Suenaga, K; Minagi, S

1998-02-01

Tray adhesive, which is used for the adhesion of elastomer rubber impression materials to a custom resin tray, lowers the retention of the impression materials to the impression modeling plastics, as some ingredients of tray adhesive make the impression modeling plastic soft and tacky. The efficacy of tray adhesive, which is used for the adhesion of elastomer rubber impression materials to a custom resin tray, on the adhesion between elastomer rubber impression material and impression modeling plastic was investigated. Four silicone rubber impression materials (two addition reaction types and two condensation reaction types), two polysulfide rubber impression materials, and one impression modeling plastic were used in this study. Tensile strength between elastomer rubber impression material and impression modeling plastic with or without the application of tray adhesive was evaluated. Although tray adhesives for both addition reaction type and both condensation reaction type of silicone impression materials and one tray adhesive for polysulfide rubber impression material increased the tensile strength between the impression material and impression modeling plastic, one tray adhesive for polysulfide rubber impression material decreased the tensile strength when sufficient drying time was not applied.

Gingival cell proliferation induced by use of a sonic toothbrush with warmed silicone rubber bristles.

PubMed

Tomofuji, Takaaki; Kusano, Hiroki; Azuma, Tetsuji; Ekuni, Daisuke; Yamamoto, Tatsuo; Watanabe, Tatsuo; Kishimoto, Takashi

2004-12-01

Toothbrushing promotes gingival cell proliferation, which may occur as the result of the physical stimulation of the gingiva. The present study evaluated the effects of temperature and silicone rubber bristles of a sonic toothbrush on gingival cell proliferation in dogs. During the 5-week experimental period, one quadrant in each of eight dogs received a different toothbrushing regimen: a manual toothbrush or a sonic toothbrush with 1) nylon, 2) silicone rubber, or 3) warmed silicone rubber bristles. The proliferative activity of gingival cells was evaluated based on expression of proliferating cell nuclear antigen (PCNA). Use of the sonic toothbrushes produced a higher density of PCNA-positive and total fibroblasts than did use of a manual toothbrush. The warm silicone rubber bristles resulted in a higher density of PCNA-positive fibroblasts compared with the cooler silicone rubber bristle. The number of PCNA-positive basal cells in the junctional epithelium also increased following electric toothbrushing with warmed silicone rubber bristles. The sonic toothbrush with silicone rubber bristles induced gingival fibroblast proliferation to a greater degree than a manual toothbrush. Warming the silicone rubber bristles increased their stimulatory effects on the proliferative activity of gingival cells.

Why dentists don't use rubber dam during endodontics and how to promote its usage?

PubMed

Madarati, Ahmad A

2016-02-25

This survey study aimed at investigating the frequency of rubber dam use during root canal treatment, identifying influencing factors for not using it by Saudi general dental practitioners (GDPs) and endodontists. It also aimed at identifying measures that increase rubber dam usage. After obtaining an ethical approval, two pilot studies were conducted on staff members at Taibah University College of Dentistry and a group of GDPs. A final online survey was constructed comprising 17 close-ended questions divided into six categories: demographics, endodontic practice, rubber dam use, alternative isolation methods, reasons for not using rubber dam, and measures and policies that increase its usage. The survey was emailed to 375 GDPs randomly selected from the dental register and all endodontists (n = 53) working in the western province, Saudi Arabia. Data were analyzed using the Chi-square and Linear-by-Linear association tests at p ≤ 0.05. The proportion of endodontists who used rubber dam (84.8 %) was significantly greater than that of GDPs (21.6 %) (p < 0.001). Significantly the highest proportion (40.5 %) did not use rubber dam because of unavailability at working place. Most rubber dam none-users (69.25 %) used a combination of other isolation means. The highest proportion of those who used rubber dam were working in the governmental sector (54.3 %). Among rubber dam users, the greatest proportion graduated from Saudi Arabia (57.8 %) compared to those graduated from Egypt (34.3 %) and Syria (22.4 %). There was a significant correlation between the patterns of rubber dam use during undergraduate training and its usage after graduation (p = 0.001). The highest proportion of participants (48.1 %) reported better undergraduate education as the most important factor that would increase rubber dam use in dental practice. Using of rubber dam was not common in Saudi general dental practice. Dentists must follow the recommended standards of care. Place of work and patterns of using rubber dam during undergraduate study were the most influencing factors. Better undergraduate education was the most important proposed measure to increase its usage. The combination of cotton rolls and saliva high-volume ejector or gauze was the most common alternative to rubber dam isolation.

40 CFR 428.80 - Applicability; description of the wet digestion reclaimed rubber subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... digestion reclaimed rubber subcategory. 428.80 Section 428.80 Protection of Environment ENVIRONMENTAL... CATEGORY Wet Digestion Reclaimed Rubber Subcategory § 428.80 Applicability; description of the wet digestion reclaimed rubber subcategory. The provisions of this subpart are applicable to process waste water...

40 CFR 428.80 - Applicability; description of the wet digestion reclaimed rubber subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... digestion reclaimed rubber subcategory. 428.80 Section 428.80 Protection of Environment ENVIRONMENTAL... Wet Digestion Reclaimed Rubber Subcategory § 428.80 Applicability; description of the wet digestion... discharges resulting from the production of reclaimed rubber by use of the wet digestion process. ...

40 CFR 428.80 - Applicability; description of the wet digestion reclaimed rubber subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... digestion reclaimed rubber subcategory. 428.80 Section 428.80 Protection of Environment ENVIRONMENTAL... CATEGORY Wet Digestion Reclaimed Rubber Subcategory § 428.80 Applicability; description of the wet digestion reclaimed rubber subcategory. The provisions of this subpart are applicable to process waste water...

40 CFR 428.80 - Applicability; description of the wet digestion reclaimed rubber subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... digestion reclaimed rubber subcategory. 428.80 Section 428.80 Protection of Environment ENVIRONMENTAL... Wet Digestion Reclaimed Rubber Subcategory § 428.80 Applicability; description of the wet digestion... discharges resulting from the production of reclaimed rubber by use of the wet digestion process. ...

40 CFR 428.80 - Applicability; description of the wet digestion reclaimed rubber subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... digestion reclaimed rubber subcategory. 428.80 Section 428.80 Protection of Environment ENVIRONMENTAL... CATEGORY Wet Digestion Reclaimed Rubber Subcategory § 428.80 Applicability; description of the wet digestion reclaimed rubber subcategory. The provisions of this subpart are applicable to process waste water...

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

USDA-ARS?s Scientific Manuscript database

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...

Evaluation of the use of rubber-tire rollers on asphalt concrete.

DOT National Transportation Integrated Search

1989-01-01

The addition of a rubber-tire roller was required on two projects on maintenance schedules and on two construction projects in 1988. The rubber-tire roller was used as an addition to the conventional rollers on one-half of each project. The rubber-ti...

Evaluation of crumb rubber in hot mix asphalt.

DOT National Transportation Integrated Search

2004-07-01

An asphalt-rubber hot mix asphalt (AR-HMA) design was created using a Superpave 12.5mm gradation and a #30 (-) mesh : crumb rubber at 20% total weight of the asphalt binder. At this point in time, asphalt rubber has only been used with HMA : that con...

27 CFR 21.125 - Rubber hydrocarbon solvent.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Rubber hydrocarbon solvent. 21.125 Section 21.125 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....125 Rubber hydrocarbon solvent. (a) Rubber hydrocarbon solvent is a petroleum derivative. (b...

27 CFR 21.125 - Rubber hydrocarbon solvent.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Rubber hydrocarbon solvent. 21.125 Section 21.125 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....125 Rubber hydrocarbon solvent. (a) Rubber hydrocarbon solvent is a petroleum derivative. (b...

A sustainability review of domestic rubber from the guayule plant

USDA-ARS?s Scientific Manuscript database

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...

Analysis of a Compressible Fluid Soft Recoil (CFSR) Concept Applied to a 155 MM Howitzer

DTIC Science & Technology

1979-03-01

Nitrile or Buna-N ( NBR ) rubber with ’ backup rings of nylotron. HITRILE NVLOTRON Piston seals An unresolved problem is that the coefficient of...fluid at atmospheric pressure Poisson’s ratio for Nitrile rubber dynamic coefficient of friction for rubber mass of recoiling parts weight of...Greene, tweed 5 Co. Palmetto catalog.) 43 [i^ - 0.50 = coefficient of friction (An approximate figure for rubber supplied by RIA Rubber

Toxicity of Pyrolysis Gases from Elastomers

NASA Technical Reports Server (NTRS)

Hilado, Carlos J.; Kosola, Kay L.; Solis, Alida N.; Kourtides, Demetrius A.; Parker, John A.

1977-01-01

The toxicity of the pyrolysis gases from six elastomers was investigated. The elastomers were polyisoprene (natural rubber), styrene-butadiene rubber (SBR), ethylene propylene diene terpolymer (EPDM), acrylonitrile rubber, chlorosulfonated polyethylene rubber, and polychloroprene. The rising temperature and fixed temperature programs produced exactly the same rank order of materials based on time to death. Acryltonitrile rubber exhibited the greatest toxicity under these test conditions; carbon monoxide was not found in sufficient concentrations to be the primary cause of death.

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.

Correlation Of Ortho-Positronium Intensity With Doppler Broadening For Rubber Above And Below The Glass Transition Temperature

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

Towry, Amanda; Quarles, C. A.

Previous research has demonstrated a correlation between the Doppler broadening S parameter and the intensity of the ortho-positronium lifetime component in polymers that depends on the composition of the polymer. On the other hand, rubber polymers do not show this correlation and behave more like liquids for which the S parameter is essentially independent of the ortho-positronium intensity. The bubble model has been suggested as an explanation of the lack of correlation in analogy with liquids, but the bubble model applied to rubber is controversial. There are two important differences between the rubber and the polymers samples: first, the rubbermore » samples at room temperature were all above the glass transition temperature (T{sub G}). Second, the rubber samples all contained sulfur and were vulcanized. These differences were investigated by first measuring the S parameter for six rubber samples below T{sub G} where the bubble model would not be expected to work. Second, raw rubber samples that did not contain any sulfur and were unvulcanized were studied at room temperature. The results show that the lack of correlation between the S parameter and the ortho-positronium intensity previously observed for vulcanized rubber is due to the inhibition of positronium formation by the sulfur in the vulcanized rubber samples rather than to the rubber being above T{sub G}.« less

Tailored Recovery of Carbons from Waste Tires for Enhanced Performance as Anodes in Lithium-ion Batteries

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

Naskar, Amit K; Bi,; Saha, Dipendu

2014-01-01

Morphologically tailored pyrolysis-recovered carbon black is utilized in lithium-ion batteries as a potential solution for adding value to waste tire-rubber-derived materials. Micronized tire rubber was digested in a hot oleum bath to yield a sulfonated rubber slurry that was then filtered, washed, and compressed into a solid cake. Carbon was recovered from the modified rubber cake by pyrolysis in a nitrogen atmosphere. The chemical pretreatment of rubber produced a carbon monolith with higher yield than that from the control (a fluffy tire-rubber-derived carbon black). The carbon monolith showed a very small volume fraction of pores of widths 3 4 nm,more » reduced specific surface area, and an ordered assembly of graphitic domains. Electrochemical studies on the recovered-carbon-based anode revealed an improved Li-ion battery performance with higher reversible capacity than that of commercial carbon materials. Anodes made with a sulfonated tire-rubber-derived carbon and a control tire-rubber-derived carbon, respectively, exhibited an initial coulombic efficiency of 80% and 45%, respectively. The reversible capacity of the cell with the sulfonated carbon as anode was 400 mAh/g after 100 cycles, with nearly 100% coulombic efficiency. Our success in producing higher performance carbon material from waste tire rubber for potential use in energy storage applications adds a new avenue to tire rubber recycling.« less

Quantification of trans-1,4-polyisoprene in Eucommia ulmoides by fourier transform infrared spectroscopy and pyrolysis-gas chromatography/mass spectrometry.

PubMed

Takeno, Shinya; Bamba, Takeshi; Nakazawa, Yoshihisa; Fukusaki, Eiichiro; Okazawa, Atsushi; Kobayashi, Akio

2008-04-01

Commercial development of trans-1,4-polyisoprene from Eucommia ulmoides Oliver (EU-rubber) requires specific knowledge on selection of high-rubber-content lines and establishment of agronomic cultivation methods for achieving maximum EU-rubber yield. The development can be facilitated by high-throughput and highly sensitive analytical techniques for EU-rubber extraction and quantification. In this paper, we described an efficient EU-rubber extraction method, and validated that the accuracy was equivalent to that of the conventional Soxhlet extraction method. We also described a highly sensitive quantification method for EU-rubber by Fourier transform infrared spectroscopy (FT-IR) and pyrolysis-gas chromatography/mass spectrometry (PyGC/MS). We successfully applied the extraction/quantification method for study of seasonal changes in EU-rubber content and molecular weight distribution.

Responses of rubber leaf phenology to climatic variations in Southwest China

NASA Astrophysics Data System (ADS)

Zhai, De-Li; Yu, Haiying; Chen, Si-Chong; Ranjitkar, Sailesh; Xu, Jianchu

2017-11-01

The phenology of rubber trees (Hevea brasiliensis) could be influenced by meteorological factors and exhibits significant changes under different geoclimates. In the sub-optimal environment in Xishuangbanna, rubber trees undergo lengthy periods of defoliation and refoliation. The timing of refoliation from budburst to leaf aging could be affected by powdery mildew disease (Oidium heveae), which negatively impacts seed and latex production. Rubber trees are most susceptible to powdery mildew disease at the copper and leaf changing stages. Understanding and predicting leaf phenology of rubber trees are helpful to develop effective means of controlling the disease. This research investigated the effect of several meteorological factors on different leaf phenological stages in a sub-optimal environment for rubber cultivation in Jinghong, Yunnan in Southwest China. Partial least square regression was used to quantify the relationship between meteorological factors and recorded rubber phenologies from 2003 to 2011. Minimum temperature in December was found to be the critical factor for the leaf phenology development of rubber trees. Comparing the delayed effects of minimum temperature, the maximum temperature, diurnal temperature range, and sunshine hours were found to advancing leaf phenologies. A comparatively lower minimum temperature in December would facilitate the advancing of leaf phenologies of rubber trees. Higher levels of precipitation in February delayed the light green and the entire process of leaf aging. Delayed leaf phenology was found to be related to severe rubber powdery mildew disease. These results were used to build predictive models that could be applied to early warning systems of rubber powdery mildew disease.

75 FR 29466 - Airworthiness Directives; Gulfstream Aerospace LP (Type Certificate Previously Held by Israel...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-26

... baggage compartment rubber seals, and replacing the baggage compartment rubber seals manufactured by Gumiyan with seals manufactured by Rubbercraft. Since the proposed AD was issued, we have received new... manufacturer of the baggage compartment rubber seals, and replacing the baggage compartment rubber seals...

40 CFR 428.90 - Applicability; description of the pan, dry digestion, and mechanical reclaimed rubber subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., dry digestion, and mechanical reclaimed rubber subcategory. 428.90 Section 428.90 Protection of... MANUFACTURING POINT SOURCE CATEGORY Pan, Dry Digestion, and Mechanical Reclaimed Rubber Subcategory § 428.90 Applicability; description of the pan, dry digestion, and mechanical reclaimed rubber subcategory. The...

40 CFR 428.90 - Applicability; description of the pan, dry digestion, and mechanical reclaimed rubber subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., dry digestion, and mechanical reclaimed rubber subcategory. 428.90 Section 428.90 Protection of... MANUFACTURING POINT SOURCE CATEGORY Pan, Dry Digestion, and Mechanical Reclaimed Rubber Subcategory § 428.90 Applicability; description of the pan, dry digestion, and mechanical reclaimed rubber subcategory. The...

40 CFR 428.90 - Applicability; description of the pan, dry digestion, and mechanical reclaimed rubber subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., dry digestion, and mechanical reclaimed rubber subcategory. 428.90 Section 428.90 Protection of... POINT SOURCE CATEGORY Pan, Dry Digestion, and Mechanical Reclaimed Rubber Subcategory § 428.90 Applicability; description of the pan, dry digestion, and mechanical reclaimed rubber subcategory. The...

40 CFR 428.90 - Applicability; description of the pan, dry digestion, and mechanical reclaimed rubber subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., dry digestion, and mechanical reclaimed rubber subcategory. 428.90 Section 428.90 Protection of... MANUFACTURING POINT SOURCE CATEGORY Pan, Dry Digestion, and Mechanical Reclaimed Rubber Subcategory § 428.90 Applicability; description of the pan, dry digestion, and mechanical reclaimed rubber subcategory. The...

40 CFR 428.90 - Applicability; description of the pan, dry digestion, and mechanical reclaimed rubber subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., dry digestion, and mechanical reclaimed rubber subcategory. 428.90 Section 428.90 Protection of... POINT SOURCE CATEGORY Pan, Dry Digestion, and Mechanical Reclaimed Rubber Subcategory § 428.90 Applicability; description of the pan, dry digestion, and mechanical reclaimed rubber subcategory. The...

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.

40 CFR 428.60 - Applicability; description of the medium-sized general molded, extruded, and fabricated rubber...

Code of Federal Regulations, 2010 CFR

2010-07-01

... medium-sized general molded, extruded, and fabricated rubber plants subcategory. 428.60 Section 428.60... RUBBER MANUFACTURING POINT SOURCE CATEGORY Medium-Sized General Molded, Extruded, and Fabricated Rubber Plants Subcategory § 428.60 Applicability; description of the medium-sized general molded, extruded, and...

40 CFR 428.60 - Applicability; description of the medium-sized general molded, extruded, and fabricated rubber...

Code of Federal Regulations, 2014 CFR

2014-07-01

... medium-sized general molded, extruded, and fabricated rubber plants subcategory. 428.60 Section 428.60... (CONTINUED) RUBBER MANUFACTURING POINT SOURCE CATEGORY Medium-Sized General Molded, Extruded, and Fabricated Rubber Plants Subcategory § 428.60 Applicability; description of the medium-sized general molded...

40 CFR 428.60 - Applicability; description of the medium-sized general molded, extruded, and fabricated rubber...

Code of Federal Regulations, 2013 CFR

2013-07-01

... medium-sized general molded, extruded, and fabricated rubber plants subcategory. 428.60 Section 428.60... (CONTINUED) RUBBER MANUFACTURING POINT SOURCE CATEGORY Medium-Sized General Molded, Extruded, and Fabricated Rubber Plants Subcategory § 428.60 Applicability; description of the medium-sized general molded...

40 CFR 63.494 - Back-end process provisions-residual organic HAP and emission limitations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... producing butyl rubber, epichlorohydrin elastomer, neoprene, and nitrile butadiene rubber shall not exceed... processes at affected sources producing butyl rubber, epichlorohydrin elastomer, neoprene, and nitrile... submitted in accordance with § 63.499(f)(1). (i) For butyl rubber, the organic HAP emission limitation shall...

40 CFR 62.14102 - Affected facilities.

Code of Federal Regulations, 2014 CFR

2014-07-01

... plastics/rubber recycling unit (as defined in 40 CFR 60.51b) are not subject to this subpart if the owner or operator of the plastics/rubber recycling unit keeps records of the weight of plastics, rubber... chemical plants or petroleum refineries that use feestocks produced by plastics/rubber recycling units are...

40 CFR 62.14102 - Affected facilities.

Code of Federal Regulations, 2012 CFR

2012-07-01

... plastics/rubber recycling unit (as defined in 40 CFR 60.51b) are not subject to this subpart if the owner or operator of the plastics/rubber recycling unit keeps records of the weight of plastics, rubber... chemical plants or petroleum refineries that use feestocks produced by plastics/rubber recycling units are...

40 CFR 62.14102 - Affected facilities.

Code of Federal Regulations, 2013 CFR

2013-07-01

... plastics/rubber recycling unit (as defined in 40 CFR 60.51b) are not subject to this subpart if the owner or operator of the plastics/rubber recycling unit keeps records of the weight of plastics, rubber... chemical plants or petroleum refineries that use feestocks produced by plastics/rubber recycling units are...

40 CFR 62.14102 - Affected facilities.

Code of Federal Regulations, 2011 CFR

2011-07-01

... plastics/rubber recycling unit (as defined in 40 CFR 60.51b) are not subject to this subpart if the owner or operator of the plastics/rubber recycling unit keeps records of the weight of plastics, rubber... chemical plants or petroleum refineries that use feestocks produced by plastics/rubber recycling units are...

40 CFR 62.14102 - Affected facilities.

Code of Federal Regulations, 2010 CFR

2010-07-01

... plastics/rubber recycling unit (as defined in 40 CFR 60.51b) are not subject to this subpart if the owner or operator of the plastics/rubber recycling unit keeps records of the weight of plastics, rubber... chemical plants or petroleum refineries that use feestocks produced by plastics/rubber recycling units are...

U-Groove aluminum weld strength improvement

NASA Technical Reports Server (NTRS)

Verderaime, V.; Vaughan, R.

1996-01-01

Though butt-welds are among the most preferred joining methods in aerostructures, their strength dependence on inelastic mechanics is generally the least understood. This study investigated experimental strain distributions across a thick aluminum U-grooved weld and identified two weld process considerations for improving the multipass weld strength. The extreme thermal expansion and contraction gradient of the fusion heat input across the groove tab thickness produces severe peaking, which induces bending under uniaxial loading. The filler strain-hardening decreased with increasing filler pass sequence, producing the weakest welds on the last pass side. Current welding schedules unknowingly compound these effects which reduce the weld strength. A depeaking index model was developed to select filler pass thicknesses, pass numbers, and sequences to improve depeaking in the welding process. The intent is to combine the strongest weld pass side with the peaking induced bending tension to provide a more uniform stress and stronger weld under axial tensile loading.

Rare-earth metal halogenide encapsulation-induced modifications in Raman spectra of single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Kharlamova, M. V.

2015-01-01

In the present work, a detailed Raman spectroscopy investigation on the single-walled carbon nanotubes (SWCNTs) filled with praseodymium chloride, terbium chloride and thulium chloride was performed. The salts were incorporated inside the SWCNTs by a capillary filling method using melts, and the high-resolution transmission electron microscopy data proved the high filling degree of the nanotube channels. A thorough analysis of the radial breathing mode and G-band of the Raman spectra of the pristine and filled SWCNTs showed that the encapsulated salts cause acceptor doping of the host nanotubes, and the doping efficiency depends on the compound. The incorporated thulium chloride has the strongest doping effect on the SWCNTs, whereas praseodymium chloride has the weakest effect. It was found that the encapsulated salts modify more significantly the electronic structure of metallic nanotubes than semiconducting SWCNTs.

Analysis of Silicones Released from Household Items and Baby Articles by Direct Analysis in Real Time-Mass Spectrometry

NASA Astrophysics Data System (ADS)

Gross, Jürgen H.

2015-03-01

Direct analysis in real time-mass spectrometry (DART-MS) enables screening of articles of daily use made of polydimethylsiloxanes (PDMS), commonly known as silicone rubber, to assess their tendency to release low molecular weight silicone oligomers. DART-MS analyses were performed on a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Flexible silicone baking molds, a watch band, and a dough scraper, as baby articles different brands of pacifiers, nipples, and a teething ring have been examined. While somewhat arbitrarily chosen, the set can be regarded as representative of household items, baby articles, and other objects made of silicone rubber. For comparison, two brands of silicone septa and as blanks a glass slide and a latex pacifier were included. Differences between the objects were mainly observed in terms of molecular weight distribution and occasional release of other compounds in addition to PDMS. Other than that, all objects made of silicone rubber released significant amounts of PDMS during DART analysis. To provide a coarse quantification, a calibration based on silicone oil was established, which delivered PDMS losses from 20 μg to >100 μg during the 16-s period per measurement. Also, the extraction of baking molds in rapeseed oil demonstrated a PDMS release at the level of 1 μg mg-1. These findings indicate a potential health hazard from frequent or long-term use of such items. This work does not intend to blame certain brands of such articles. Nonetheless, a higher level of awareness of this source of daily silicone intake is suggested.

Determination of Hydrophobic Contact Angle of Epoxy Resin Compound Silicon Rubber and Silica

NASA Astrophysics Data System (ADS)

Syakur, Abdul; Hermawan; Sutanto, Heri

2017-04-01

Epoxy resin is a thermosetting polymeric material which is very good for application of high voltage outdoor insulator in electrical power system. This material has several advantages, i.e. high dielectric strength, light weight, high mechanical strength, easy to blend with additive, and easy maintenance if compared to that of porcelain and glass outdoor insulators which are commonly used. However, this material also has several disadvantages, i.e. hydrophilic property, very sensitive to aging and easily degraded when there is a flow of contaminants on its surface. The research towards improving the performance of epoxy resin insulation materials were carried out to obtain epoxy resin insulating material with high water repellent properties and high surface tracking to aging. In this work, insulating material was made at room temperature vulcanization, with material composition: Diglycidyl Ether Bisphenol A (DGEBA), Metaphenylene Diamine (MPDA) as hardener with stoichiometric value of unity, and nanosilica mixed with Silicon Rubber (SiR) with 10% (RTV21), 20% (RTV22), 30% (RTV23), 40% (RTV24) and 50% (RTV25) variation. The usage of nanosilica and Silicon Rubber (SIR) as filler was expected to provide hydrophobic properties and was able to increase the value of surface tracking of materials. The performance of the insulator observed were contact angle of hydrophobic surface materials. Tests carried out using Inclined Plane Tracking procedure according to IEC 60-587: 1984 with Ammonium Chloride (NH4Cl) as contaminants flowed using peristaltic pumps. The results show that hydrophobic contact angle can be determined from each sample, and RTV25 has maximum contact angle among others.

Analysis of silicones released from household items and baby articles by direct analysis in real time-mass spectrometry.

PubMed

Gross, Jürgen H

2015-03-01

Direct analysis in real time-mass spectrometry (DART-MS) enables screening of articles of daily use made of polydimethylsiloxanes (PDMS), commonly known as silicone rubber, to assess their tendency to release low molecular weight silicone oligomers. DART-MS analyses were performed on a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Flexible silicone baking molds, a watch band, and a dough scraper, as baby articles different brands of pacifiers, nipples, and a teething ring have been examined. While somewhat arbitrarily chosen, the set can be regarded as representative of household items, baby articles, and other objects made of silicone rubber. For comparison, two brands of silicone septa and as blanks a glass slide and a latex pacifier were included. Differences between the objects were mainly observed in terms of molecular weight distribution and occasional release of other compounds in addition to PDMS. Other than that, all objects made of silicone rubber released significant amounts of PDMS during DART analysis. To provide a coarse quantification, a calibration based on silicone oil was established, which delivered PDMS losses from 20 μg to >100 μg during the 16-s period per measurement. Also, the extraction of baking molds in rapeseed oil demonstrated a PDMS release at the level of 1 μg mg(-1). These findings indicate a potential health hazard from frequent or long-term use of such items. This work does not intend to blame certain brands of such articles. Nonetheless, a higher level of awareness of this source of daily silicone intake is suggested.

Fuel and Fuel System Materials Compatibility Test Program for A JP-8+100 Fuel Additive. Volume 1: Thermal Stability Additive Package BetzDearborn Spec Aid(Registered) 8Q462

DTIC Science & Technology

2001-10-01

SAE Rings, Sealing, Butadiene-Acrylonitrile ( NBR ), Rubber Fuel and Low Temperature Resistant 60 - 70 MIL-R-83248C Rubber , Fluorocarbon...KAPTON/TEFLON (COMPOSITE) WIRE I.I.10 34 VI. REFERENCE DOCUMENTS Non-Metallics MIL-HDBK-149B Military Standardization Hand Book Rubber ...ASTM D-1414 Standard Test Methods for Rubber O-Rings ASTM D-412 Type II Standard Test Methods for Vulcanized Rubber and Thermoplastic

Effect of electron beam irradiation on the properties of crosslinked rubbers

NASA Astrophysics Data System (ADS)

Banik, Indranil; Bhowmick, Anil K.

2000-05-01

Influence of electron beam (EB) irradiation on the mechanical and dynamic mechanical properties of crosslinked fluorocarbon (FKM) rubber, natural rubber (NR), ethylene propylene diene monomer (EPDM) rubber and nitrile rubber (NBR) has been investigated. The modulus, gel fraction, glass transition temperature ( Tg) and storage modulus increased, while the elongation at the break and the loss tangent (tan δ) Tg decreased. FKM and NBR vulcanizates have been shown to have EB radiation resistance up to 1500 kGy.

The Long-Term Effectiveness of Chemical vs. Polymeric Antiozonants in Rubber

DTIC Science & Technology

1976-02-01

August 1954. 2. Lerner, M.E., Rubber Age . 105, 57, December 1973. 3. Buist, J., British Patent 939, 359 (Application made in Canada, No. 802, 137...J.M., Kindle, R.W., and Mazzeo, R.A., Rubber World. 98. 67, 1966 (Abstract only). 6 Samuels, M.E., and Wirth, K.H., Rubber Age . 99. 73, 1967. 7... Age . 101. 47, 1969. 12 ASTM Standards on Rubber Products, March 1968, American Society for Testing and Materials, 1916 Race St., Philadelphia, Pa

Asphalt concrete modified by rubber crumbs in transport construction.

NASA Astrophysics Data System (ADS)

Duhovny, G. S.; Karpenko, AV

2018-03-01

High-temperature and low-temperature characteristics of the rubber-bitumen binder and rubber asphalt concrete based on it are researched. The determination method of binder’s low-temperature characteristics is offered. The estimation of binder’s and pavement’s stability against technological and operational aging is evaluated. Estimation of environmental and economic aspects of using rubber crumbs is made. The possibility of using rubber crumbs as modifier of organic binder for production of asphalt concrete on its base is justified.

Rubber friction directional asymmetry

NASA Astrophysics Data System (ADS)

Tiwari, A.; Dorogin, L.; Steenwyk, B.; Warhadpande, A.; Motamedi, M.; Fortunato, G.; Ciaravola, V.; Persson, B. N. J.

2016-12-01

In rubber friction studies it is usually assumed that the friction force does not depend on the sliding direction, unless the substrate has anisotropic properties, like a steel surface grinded in one direction. Here we will present experimental results for rubber friction, where we observe a strong asymmetry between forward and backward sliding, where forward and backward refer to the run-in direction of the rubber block. The observed effect could be very important in tire applications, where directional properties of the rubber friction could be induced during braking.

On the response of rubbers at high strain rates.

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

Niemczura, Johnathan Greenberg

In this report, we examine the propagation of tensile waves of finite deformation in rubbers through experiments and analysis. Attention is focused on the propagation of one-dimensional dispersive and shock waves in strips of latex and nitrile rubber. Tensile wave propagation experiments were conducted at high strain-rates by holding one end fixed and displacing the other end at a constant velocity. A high-speed video camera was used to monitor the motion and to determine the evolution of strain and particle velocity in the rubber strips. Analysis of the response through the theory of finite waves and quantitative matching between themore » experimental observations and analytical predictions was used to determine an appropriate instantaneous elastic response for the rubbers. This analysis also yields the tensile shock adiabat for rubber. Dispersive waves as well as shock waves are also observed in free-retraction experiments; these are used to quantify hysteretic effects in rubber.« less

Adding crumb rubber into exterior wall materials.

PubMed

Zhu, Han; Thong-On, Norasit; Zhang, Xiong

2002-10-01

In Arizona US, most houses are built with walls covered by stuccos/coatings/mortars. This paper presents an explorative investigation of adding crumb rubber into stuccos/coatings/mortars. A series of experiments are conducted to examine the thermal and mechanical performance of the crumb rubber mixes. The results show that, the mixes with crumb rubber do exhibit more desirable performances like being high in crack-resistance and thermal insulation, and low in thermal expansion/contraction. The drawback for the crumb rubber mixes is the reduction in compressive strength, but which can be compensated by other means. As a site experiment, an area of 100 square-feet of crumb rubber coatings for two mix designs is sprayed on a tire-adobe wall. After being sprayed more than 14 months, the coatings apparently are in good condition. Significance of this study is that this practice, if accepted, will yield improved products that consume large quantities of crumb rubber.

40 CFR 63.494 - Back-end process provisions-residual organic HAP and emission limitations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... produced by the emulsion process, polybutadiene rubber and styrene butadiene rubber produced by the... styrene butadiene rubber produced by the emulsion process: (i) A monthly weighted average of 0.40 kg... than a solution or emulsion process, polybutadiene rubber produced by any process other than a solution...

Embedded Carbon Nanotube Networks for Damage Precursor Detection

DTIC Science & Technology

2014-01-01

3Thostenson, E. T.; Chou, T.-W. Carbon Nanotube Networks: Sensing of Distributed Strain and Damage for Life Prediction and Self - Healing . Advanced...3 Figure 2. Rubber dogbone mold...room temperature vulcanizing rubber to create the final mold. The rubber was mixed with Tin NW Catalyst at a 10:1 ratio. The viscous liquid rubber

Breeding Guayule: how far have we come and how far can we go?

USDA-ARS?s Scientific Manuscript database

Guayule lines from the 1940s yielded less than 350 lb rubber/acre/year. Using the available germplasm from this earlier era, guayule rubber yields have increased significantly, between 830 lb rubber/acre/year and 1,000 lb rubber/ acre, through the efforts of a few, but dedicated researchers. Improve...

40 CFR 63.498 - Back-end process provisions-recordkeeping.

Code of Federal Regulations, 2010 CFR

2010-07-01

... be the crumb rubber dry weight of the rubber leaving the stripper. (iv) The organic HAP content of... stripper. (B) For solution processes, this quantity shall be the crumb rubber dry weight of the crumb rubber leaving the stripper. (iii) The hourly average of all stripper parameter results; (iv) If one or...

40 CFR 60.32b - Designated facilities.

Code of Federal Regulations, 2014 CFR

2014-07-01

... plastics/rubber recycling unit (as defined in § 60.51b) are not subject to this subpart if the owner or operator of the plastics/rubber recycling unit keeps records of the weight of plastics, rubber, and/or... petroleum refineries that use feedstocks produced by plastics/rubber recycling units are not subject to this...

40 CFR 60.32b - Designated facilities.

Code of Federal Regulations, 2010 CFR

2010-07-01

... plastics/rubber recycling unit (as defined in § 60.51b) are not subject to this subpart if the owner or operator of the plastics/rubber recycling unit keeps records of the weight of plastics, rubber, and/or... petroleum refineries that use feedstocks produced by plastics/rubber recycling units are not subject to this...

40 CFR 60.32b - Designated facilities.

Code of Federal Regulations, 2011 CFR

2011-07-01

... plastics/rubber recycling unit (as defined in § 60.51b) are not subject to this subpart if the owner or operator of the plastics/rubber recycling unit keeps records of the weight of plastics, rubber, and/or... petroleum refineries that use feedstocks produced by plastics/rubber recycling units are not subject to this...

40 CFR 60.32b - Designated facilities.

Code of Federal Regulations, 2013 CFR

2013-07-01

... plastics/rubber recycling unit (as defined in § 60.51b) are not subject to this subpart if the owner or operator of the plastics/rubber recycling unit keeps records of the weight of plastics, rubber, and/or... petroleum refineries that use feedstocks produced by plastics/rubber recycling units are not subject to this...

40 CFR 60.32b - Designated facilities.

Code of Federal Regulations, 2012 CFR

2012-07-01

... plastics/rubber recycling unit (as defined in § 60.51b) are not subject to this subpart if the owner or operator of the plastics/rubber recycling unit keeps records of the weight of plastics, rubber, and/or... petroleum refineries that use feedstocks produced by plastics/rubber recycling units are not subject to this...

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.

Preparation of vinyl acetate grafted natural rubber by irradiation method

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

Porntrairat, A.; Pattamaprom, C.

Improvement in properties of natural rubber could be done by several methods. In this research, gamma radiation technique, which is simple, accurate, easy to control and clean, was applied to enhance the properties of natural rubber (NR) in latex state. The purpose of this research is to study the appropriate condition for preparing grafted natural rubber latex by using irradiation method. Vinyl acetate monomers (VAc) were grafted onto natural rubber latex (NR-g-PVAc) at 0-10 kGys by gamma radiation from Cobalt-60 source at room temperature. Physical properties of grafted natural rubber such as chloroform number, swelling ratio and gel content weremore » measured. The VAc content of NR-g-PVAc was investigated by titration and visualized by FTIR spectroscopy. The FTIR spectra of NR-g-PVAc prepared at 0-10 kGys showed characteristic peaks of the vinyl acetate confirming that VAc could be grafted onto natural rubber molecular chains effectively under appropriate irradiation conditions. From the result, radiation grafting was found to be a useful technique for grafting of vinyl acetate onto natural rubber.« less

Effect of type and content of tackifier on adhesion of natural rubber and reclaimed natural rubber based sealant

NASA Astrophysics Data System (ADS)

Raethong, P.; Boonkerd, K.

2017-07-01

Adhesion property of natural rubber (NR) and reclaimed natural rubber (RNR) based sealant with concrete was studied here. The effect of tackifier type and loading on the tensile properties of the rubber based sealant sandwished between two flat cements was evaluated. There are three different tackifiers including Coumarone-indene resin (CI), petro resin (PE) and gum rosin (GR). The result initially showed that at the 20 phr of tackifier both NR and RNR sealant mixed with CI consumed the highest force to separate the rubber based sealant from the concrete. This might be due to the highest compatiblility between CI and rubber. Regardless of the tackifier type, all NR based sealants showed the cohesive failure while all RNR based sealants only showed the adhesive failure. Moreover, the NR based sealant seemed to be stronger than the RNR based one. When considering the effect of CI loading on the adhesion, it was shown that for both NR and RNR based sealents, the highest stress was observed when the rubber based sealant loaded with the 20 phr of CI.

Self-Sealing Cementitious Materials by Using Water-Swelling Rubber Particles

PubMed Central

Lv, Leyang; Schlangen, Erik; Xing, Feng

2017-01-01

Water ingress into cracked concrete structures is a serious problem, as it can cause leakage and reinforcement corrosion and thus reduce functionality and safety of the structures. In this study, the application of water-swelling rubber particles for providing the cracked concrete a self-sealing function was developed. The feasibility of applying water-swelling rubber particles and the influence of incorporating water-swelling rubber particles on the mechanical properties of concrete was investigated. The self-sealing efficiency of water-swelling rubber particles with different content and particle size was quantified through a permeability test. The sealing effect of the water swelling rubber particles was monitored by X-ray computed tomography. The experimental results show that, by using 6% of these water swelling rubber particles as a replacement of aggregates in concrete, up to 64% and 61% decrease of water permeability was realized for 0.7 mm and 1.0 mm cracks. Furthermore, when the concrete cracks, the water swelling rubber particles can act as a crack bridging filler, preventing the crack from fully separating the specimens in two pieces. PMID:28829384

Influence of matching solubility parameter of polymer matrix and CNT on electrical conductivity of CNT/rubber composite

PubMed Central

Ata, Seisuke; Mizuno, Takaaki; Nishizawa, Ayumi; Subramaniam, Chandramouli; Futaba, Don N.; Hata, Kenji

2014-01-01

We report a general approach to fabricate elastomeric composites possessing high electrical conductivity for applications ranging from wireless charging interfaces to stretchable electronics. By using arbitrary nine kinds of rubbers as matrices, we experimentally demonstrate that the matching the solubility parameter of CNTs and the rubber matrix is important to achieve higher electrical conductivity in CNT/rubber composite, resulting in continuous conductive pathways leading to electrical conductivities as high as 15 S/cm with 10 vol% CNT in fluorinated rubber. Further, using thermodynamic considerations, we demonstrate an approach to mix CNTs to arbitrary rubber matrices regardless of solubility parameter of matrices by adding small amounts of fluorinated rubber as a polymeric-compatibilizer of CNTs. We thereby achieved electrical conductivities ranging from 1.2 to 13.8 S/cm (10 vol% CNTs) using nine varieties of rubber matrices differing in chemical structures and physical properties. Finally, we investigated the components of solubility parameter of CNT by using Hansen solubility parameters, these findings may useful for controlling solubility parameter of CNTs. PMID:25434701

Experimental Investigation on Damping Property of Coarse Aggregate Replaced Rubber Concrete

NASA Astrophysics Data System (ADS)

Sugapriya, P.; Ramkrishnan, R.; Keerthana, G.; Saravanamurugan, S.

2018-02-01

Rubber has good damping and vibrational characteristics and can reduce cracking significantly due to its elastic nature. This property of rubber can be incorporated in concrete to control vibrations and create better pavements. Crumb Rubber on being dumped in landfills has serious repercussions and causes soil and land pollution. An innovative use of waste tires is shredding them into small pieces and using them as a replacement for coarse aggregate. Crumb rubber is obtained by chopping scrap tires, and in this study it was added in two different sets named SET 1 - Treated Crumb Rubber and concrete, and SET 2 - Treated Crumb rubber with Ultra Fine GGBS as admixture in concrete. Coarse aggregate replaces Rubber in each of the 2 SET’s in proportions of 5, 10, 15 and 20%. Properties like Compressive Strength, Young’s Modulus, Direct and Semi direct Ultrasonic Pulse Velocity, Sorptivity, Damping ratio and Frequency were found out. Deformation and mode shape were studied with modal analysis and static analysis by applying a uniform pressure corresponding to the highest compressive strength of the slab, using ANSYS.

A low-cost efficient and durable low-temperature solar collector

NASA Astrophysics Data System (ADS)

Odonnell, T. P.

The considered collector utilizes a material made of ethylene-propylene-diene-monomer (EPDM). This material has been used in solar systems to heat domestic water, pools, spas, and homes by radiant energy. EPDM or ethylene propylene rubber compounds are synthetic elastomers. EPDM elastomers combine superior ozone, good heat and oxygen resistance, and very good low temperature properties to produce a compound with excellent overall age resistance. The material is extruded into 4.4 inch wide mats. Each mat has six small tubes alternating with thin webbing. The absorber mat will adhere to any clean building surface with the use of thermosetting construction-grade mastic adhesive. Carbon black contained in the mat material acts to increase the solar absorptivity. Their low cost makes the elastomers commercially very attractive. The efficiency and durability of the material are discussed.

Rubber gloves biodegradation by a consortium, mixed culture and pure culture isolated from soil samples.

PubMed

Nawong, Chairat; Umsakul, Kamontam; Sermwittayawong, Natthawan

2018-02-03

An increasing production of natural rubber (NR) products has led to major challenges in waste management. In this study, the degradation of rubber latex gloves in a mineral salt medium (MSM) using a bacterial consortium, a mixed culture of the selected bacteria and a pure culture were studied. The highest 18% weight loss of the rubber gloves were detected after incubated with the mixed culture. The increased viable cell counts over incubation time indicated that cells used rubber gloves as sole carbon source leading to the degradation of the polymer. The growth behavior of NR-degrading bacteria on the latex gloves surface was investigated using the scanning electron microscope (SEM). The occurrence of the aldehyde groups in the degradation products was observed by Fourier Transform Infrared Spectroscopy analysis. Rhodococcus pyridinivorans strain F5 gave the highest weight loss of rubber gloves among the isolated strain and posses latex clearing protein encoded by lcp gene. The mixed culture of the selected strains showed the potential in degrading rubber within 30 days and is considered to be used efficiently for rubber product degradation. This is the first report to demonstrate a strong ability to degrade rubber by Rhodococcus pyridinivorans. Copyright © 2018. Published by Elsevier Editora Ltda.

Image Classification of Ribbed Smoked Sheet using Learning Vector Quantization

NASA Astrophysics Data System (ADS)

Rahmat, R. F.; Pulungan, A. F.; Faza, S.; Budiarto, R.

2017-01-01

Natural rubber is an important export commodity in Indonesia, which can be a major contributor to national economic development. One type of rubber used as rubber material exports is Ribbed Smoked Sheet (RSS). The quantity of RSS exports depends on the quality of RSS. RSS rubber quality has been assigned in SNI 06-001-1987 and the International Standards of Quality and Packing for Natural Rubber Grades (The Green Book). The determination of RSS quality is also known as the sorting process. In the rubber factones, the sorting process is still done manually by looking and detecting at the levels of air bubbles on the surface of the rubber sheet by naked eyes so that the result is subjective and not so good. Therefore, a method is required to classify RSS rubber automatically and precisely. We propose some image processing techniques for the pre-processing, zoning method for feature extraction and Learning Vector Quantization (LVQ) method for classifying RSS rubber into two grades, namely RSS1 and RSS3. We used 120 RSS images as training dataset and 60 RSS images as testing dataset. The result shows that our proposed method can give 89% of accuracy and the best perform epoch is in the fifteenth epoch.

Below-ground interspecific competition for water in a rubber agroforestry system may enhance water utilization in plants

PubMed Central

Wu, Junen; Liu, Wenjie; Chen, Chunfeng

2016-01-01

Rubber-based (Hevea brasiliensis) agroforestry systems are regarded as the best way to improve the sustainability of rubber monocultures, but few reports have examined water use in such systems. Accordingly, we tested whether interplanting facilitates water utilization of rubber trees using stable isotope (δD, δ18O, and δ13C) methods and by measuring soil water content (SWC), shoot potential, and leaf C and N concentrations in a Hevea-Flemingia agroforestry system in Xishuangbanna, southwestern China. We detected a big difference in the utilization of different soil layer water between both species in this agroforestry system, as evidenced by the opposite seasonal fluctuations in both δD and δ18O in stem water. However, similar predawn shoot potential of rubber trees at both sites demonstrating that the interplanted species did not affect the water requirements of rubber trees greatly. Rubber trees with higher δ13C and more stable physiological indexes in this agroforestry system showed higher water use efficiency (WUE) and tolerance ability, and the SWC results suggested this agroforestry is conductive to water conservation. Our results clearly indicated that intercropping legume plants with rubber trees can benefit rubber trees own higher N supply, increase their WUE and better utilize soil water of each soil layer. PMID:26781071

Below-ground interspecific competition for water in a rubber agroforestry system may enhance water utilization in plants.

PubMed

Wu, Junen; Liu, Wenjie; Chen, Chunfeng

2016-01-19

Rubber-based (Hevea brasiliensis) agroforestry systems are regarded as the best way to improve the sustainability of rubber monocultures, but few reports have examined water use in such systems. Accordingly, we tested whether interplanting facilitates water utilization of rubber trees using stable isotope (δD, δ(18)O, and δ(13)C) methods and by measuring soil water content (SWC), shoot potential, and leaf C and N concentrations in a Hevea-Flemingia agroforestry system in Xishuangbanna, southwestern China. We detected a big difference in the utilization of different soil layer water between both species in this agroforestry system, as evidenced by the opposite seasonal fluctuations in both δD and δ(18)O in stem water. However, similar predawn shoot potential of rubber trees at both sites demonstrating that the interplanted species did not affect the water requirements of rubber trees greatly. Rubber trees with higher δ(13)C and more stable physiological indexes in this agroforestry system showed higher water use efficiency (WUE) and tolerance ability, and the SWC results suggested this agroforestry is conductive to water conservation. Our results clearly indicated that intercropping legume plants with rubber trees can benefit rubber trees own higher N supply, increase their WUE and better utilize soil water of each soil layer.

Evapotranspiration of rubber ( Hevea brasiliensis ) cultivated at two plantation sites in Southeast Asia: RUBBER EVAPOTRANSPIRATION IN SE ASIA

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

Giambelluca, Thomas W.; Mudd, Ryan G.; Liu, Wen

The expansion of rubber (Hevea brasiliensis) cultivation to higher latitudes and higher elevations in southeast Asia is part of a dramatic shift in the direction of rural land cover change in the region toward more tree covered landscapes. To investigate the possible effects of increasing rubber cultivation in the region on ecosystem services including water cycling, eddy covariance towers were established to measure ecosystem fluxes within two rubber plantations, one each in Bueng Kan, northeastern Thailand, and Kampong Cham, central Cambodia. The results show that evapotranspiration (ET) at both sites is strongly related to variations in available energy and leafmore » area, and moderately controlled by soil moisture. Measured mean annual ET was 1128 and 1272 mm for the Thailand and Cambodia sites, respectively. After adjustment for energy closure, mean annual was estimated to be 1211 and 1459 mm yr at the Thailand and Cambodia sites, respectively. Based on these estimates and that of another site in Xishuangbanna, southwestern China, it appears that of rubber is higher than that of other tree dominated land covers in the region, including forest. While measurements by others in non rubber tropical ecosystems indicate that at high net radiation sites is at most only slightly higher than for sites with lower net radiation, mean annual rubber increases strongl with increasing net radiation across the three available rubber plantation observation sites. With the continued expansion of tree dominated land covers, including rubber cultivation, in southeast Asia, the possible association between commercially viable, fast growing tree crop species Giambelluca et al. Evapotranspiration of rubber (Havea brasiliensis) cultivated at two sites in southeast Asia and their relatively high water use raises concerns about potential effects on water and food security.« less

Comparative Analysis of Latex Transcriptome Reveals Putative Molecular Mechanisms Underlying Super Productivity of Hevea brasiliensis

PubMed Central

Li, Heping; Fan, Yujie; Yang, Jianghua; Qi, Jiyan; Li, Huibo

2013-01-01

Increasing demand for natural rubber prompts studies into the mechanisms governing the productivity of rubber tree ( Hevea brasiliensis ). It is very interesting to notice that a rubber tree of clone PR107 in Yunnan, China is reported to yield more than 20 times higher than the average rubber tree. This super-high-yielding (SHY) rubber tree (designated as SY107), produced 4.12 kg of latex (cytoplasm of rubber producing laticifers, containing about 30% of rubber) per tapping, more than 7-fold higher than that of the control. This rubber tree is therefore a good material to study how the rubber production is regulated at a molecular aspect. A comprehensive cDNA-AFLP transcript profiling was performed on the latex of SY107 and its average counterparts by using the 384 selective primer pairs for two restriction enzyme combinations (ApoI/MseI and TaqI/MseI). A total of 746 differentially expressed (DE) transcript-derived fragments (TDFs) were identified, of which the expression patterns of 453 TDFs were further confirmed by RT-PCR. These RT-PCR confirmed TDFs represented 352 non-redundant genes, of which 215 had known or partially known functions and were grouped into 10 functional categories. The top three largest categories were transcription and protein synthesis (representing 24.7% of the total genes), defense and stress (15.3%), and primary and secondary metabolism (14.0%). Detailed analysis of the DE-genes suggests notable characteristics of SHY phenotype in improved sucrose loading capability, rubber biosynthesis-preferred sugar utilization, enhanced general metabolism and timely stress alleviation. However, the SHY phenotype has little correlation with rubber-biosynthesis pathway genes. PMID:24066172

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

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. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

DESI-MS imaging and NMR spectroscopy to investigate the influence of biodiesel in the structure of commercial rubbers.

PubMed

Silva, Lorena M A; Alves Filho, Elenilson G; Simpson, André J; Monteiro, Marcos R; Cabral, Elaine; Ifa, Demian; Venâncio, Tiago

2017-10-01

Biodiesel has been introduced as an energetic matrix in several countries around the world. However, the affinity of biodiesel with the components of petrodiesel engines is a growing concern. In order to obtain information regarding the effect of biodiesel on the rubber structure, nuclear magnetic resonance technics under a new technology named as comprehensive multiphase (CMP NMR) and the imaging through desorption electrospray ionization mass spectrometry (DESI-MS imaging) were used. The 1 H CMP-DOSY NMR showed the entrapped fuel into the rubber cavities, which the higher constraint caused by the rubber structure is related to the smaller diffusion coefficient. The less affected type of rubber by biodiesel was ethylene-propylene-diene monomer (EPDM), and the most affected was synthetic rubber nitrile (NBR). The 13 C CMP MAS-SPE experiments also confirmed that the internal region of EPDM was less accessible to the biodiesel molecules (no fuels detected) while other rubbers were more susceptible to the penetration of the fuel. DESI-MS imaging revealed for the first time the topography of the rubbers exposed to fuels. The biodiesel molecules entrapped at the EPDM and NBR pores were in oxidized form, which might degrade the rubber structure at long exposure time. The employed technics enabled the study of dynamic and molecular structure of the mixing complex multiphase. The DOSY under CMP used in this study could prove helpful in assessing the interactions throughout all physical phases (liquid, solid, and gel or semi-solid) by observing swellability caused by the fuel in the rubber. In addition, the DESI-MS was especially valuable to detect the degradation products of biodiesel entangled at the rubber structure. In our knowledge, this was the first report in which chemical changes of commercial rubbers induced by biodiesel and petrodiesel were investigated by means of DESI-MS and DOSY NMR. Copyright © 2017 Elsevier B.V. All rights reserved.

Monitoring rubber plantation expansion using Landsat data time series and a Shapelet-based approach

NASA Astrophysics Data System (ADS)

Ye, Su; Rogan, John; Sangermano, Florencia

2018-02-01

The expansion of tree plantations in tropical forests for commercial rubber cultivation threatens biodiversity which may affect ecosystem services, and hinders ecosystem productivity, causing net carbon emission. Numerous studies refer to the challenge of reliably distinguishing rubber plantations from natural forest, using satellite data, due to their similar spectral signatures, even when phenology is incorporated into an analysis. This study presents a novel approach for monitoring the establishment and expansion of rubber plantations in Seima Protection Forest (SPF), Cambodia (1995-2015), by detecting and analyzing the 'shapelet' structure in a Landsat-NDVI time series. This paper introduces a new classification procedure consisting of two steps: (1) an exhaustive-searching algorithm to detect shapelets that represent a period for relatively low NDVI values within an image time series; and (2) a t-test used to determine if NDVI values of detected shapelets are significantly different than their non-shapelet trend, thereby indicating the presence of rubber plantations. Using this approach, historical rubber plantation events were mapped over the twenty-year timespan. The shapelet algorithm produced two types of information: (1) year of rubber plantation establishment; and (2) pre-conversion land-cover type (i.e., agriculture, or natural forest). The overall accuracy of the rubber plantation map for the year of 2015 was 89%. The multi-temporal map products reveal that more than half of the rubber planting activity (57%) took place in 2010 and 2011, following the granting of numerous rubber concessions two years prior. Seventy-three percent of the rubber plantations were converted from natural forest and twenty-three percent were established on non-forest land-cover. The shapelet approach developed here can be used reliably to improve our understanding of the expansion of rubber production beyond Seima Protection Forest of Cambodia, and likely elsewhere in the tropics.

Exposure to rubber fume and rubber process dust in the general rubber goods, tyre manufacturing and retread industries.

PubMed

Dost, A A; Redman, D; Cox, G

2000-08-01

This study assesses the current patterns and levels of exposure to rubber fume and rubber process dust in the British rubber industry and compares and contrasts the data obtained from the general rubber goods (GRG), retread tire (RT) and new tire (NT) sectors. A total of 179 rubber companies were visited and data were obtained from 52 general rubber goods, 29 retread tire and 7 new tire manufacturers. The survey was conducted using a questionnaire and included a walk-through inspection of the workplace to assess the extent of use of control measures and the nature of work practices being employed. The most recent (predominantly 1995-97) exposure monitoring data for rubber fume and rubber process dust were obtained from these companies; no additional sampling was conducted for the purpose of this study. In addition to the assessment of exposure data, evaluation of occupational hygiene reports for the quality of information and advice was also carried out.A comparison of the median exposures for processes showed that the order of exposure to rubber fume (E, in mg m(-3)) is: E(moulding) (0.40) approximately E(extrusion) (0.33)>E(milling) (0.18) for GRG; E(press) (0. 32)>E(extrusion) (0.19)>E(autoclave) (0.10) for RT; and E(press) (0. 22) approximately E(all other) (0.22) for NT. The order of exposure to rubber fume between sectors was E(GRG) (0.40)>E(RT) (0.32)>E(NT) (0.22). Median exposures to rubber process dust in the GRG was E(weighing) (4.2)>E(mixing) (1.2) approximately E(milling) (0.8) approximately E(extrusion) (0.8) and no significant difference (P=0. 31) between GRG and NT sectors. The findings compare well with the study carried out in the Netherlands [Kromhout et al. (1994), Annals of Occupational Hygiene 38(1), 3-22], and it is suggested that the factors governing the significant differences noted between the three sectors relate principally to the production and task functions and also to the extent of controls employed. Evaluation of occupational hygiene reports indicated a number of shortcomings including lack of suitable and sufficient information with regard to sampling and analytical methods in use, poor sampling strategy, lack of appreciation regarding true rubber process dust, and a poor understanding of the principles of control for substances assigned maximum exposure limits.

Soil methane and CO2 fluxes in rainforest and rubber plantations

NASA Astrophysics Data System (ADS)

Lang, Rong; Blagodatsky, Sergey; Goldberg, Stefanie; Xu, Jianchu

2017-04-01

Expansion of rubber plantations in South-East Asia has been a land use transformation trend leading to losses of natural forest cover in the region. Besides impact on ecosystem carbon stocks, this conversion influences the dynamics of greenhouse gas fluxes from soil driven by microbial activity, which has been insufficiently studied. Aimed to understand how land use change affects the soil CO2 and CH4 fluxes, we measured surface gas fluxes, gas concentration gradient, and 13C signature in CH4 and soil organic matter in profiles in a transect in Xishuangbanna, including a rainforest site and three rubber plantation sites with age gradient. Gas fluxes were measured by static chamber method and open chamber respiration system. Soil gases were sampled from installed gas samplers at 5, 10, 30, and 75cm depth at representative time in dry and rainy season. The soil CO2 flux was comparable in rainforest and old rubber plantations, while young rubber plantation had the lowest rate. Total carbon content in the surface soil well explained the difference of soil CO2 flux between sites. All sites were CH4 sinks in dry season and uptake decreased in the order of rainforest, old rubber plantations and young rubber plantation. From dry season to rainy season, CH4 consumption decreased with increasing CH4 concentration in the soil profile at all depths. The enrichment of methane by 13CH4 shifted towards to lowerδ13C, being the evidence of enhanced CH4 production process while net surface methane flux reflected the consumption in wet condition. Increment of CH4 concentration in the profile from dry to rainy season was higher in old rubber plantation compared to rainforest, while the shifting of δ13CH4 was larger in rainforest than rubber sites. Turnover rates of soil CO2 and CH4 suggested that the 0-5 cm surface soil was the most active layer for gaseous carbon exchange. δ13C in soil organic matter and soil moisture increased from rainforest, young rubber plantation to old rubber plantations. Conversion the forest into rubber plantation decreased soil respiration in young plantation and it recovered during rubber development. However, the CH4consumption by tropical upland forest soil decreased in converted rubber plantations of all ages, with more decrement in old plantation. Change forest into rubber plantations weakened the soil function as CH4 sink.

49 CFR 179.201-3 - Lined tanks.

Code of Federal Regulations, 2011 CFR

2011-10-01

...-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.201-3 Lined tanks. (a) Rubber-lined tanks. (1) Each tank or each compartment thereof must be lined with acid-resistant rubber or other approved rubber... double thickness. The rubber lining must overlap at least 11/2 inches at all edges which must be straight...

49 CFR 179.201-3 - Lined tanks.

Code of Federal Regulations, 2012 CFR

2012-10-01

...-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.201-3 Lined tanks. (a) Rubber-lined tanks. (1) Each tank or each compartment thereof must be lined with acid-resistant rubber or other approved rubber... double thickness. The rubber lining must overlap at least 11/2 inches at all edges which must be straight...

49 CFR 179.201-3 - Lined tanks.

Code of Federal Regulations, 2013 CFR

2013-10-01

...-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.201-3 Lined tanks. (a) Rubber-lined tanks. (1) Each tank or each compartment thereof must be lined with acid-resistant rubber or other approved rubber... double thickness. The rubber lining must overlap at least 11/2 inches at all edges which must be straight...

49 CFR 179.201-3 - Lined tanks.

Code of Federal Regulations, 2014 CFR

2014-10-01

...-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.201-3 Lined tanks. (a) Rubber-lined tanks. (1) Each tank or each compartment thereof must be lined with acid-resistant rubber or other approved rubber... double thickness. The rubber lining must overlap at least 11/2 inches at all edges which must be straight...

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

Code of Federal Regulations, 2013 CFR

2013-04-01

... 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 rubber-modified poly(p-methylstyrene) identified in this section may be safely used as components of articles...

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

Code of Federal Regulations, 2014 CFR

2014-04-01

... 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 rubber-modified poly(p-methyl-styrene). Poly(p-methylstyrene) and rubber-modified poly(p-methylstyrene) identified...

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... Poly(p-methylstyrene) and rubber-modified poly(p-methyl-styrene). Poly(p-methylstyrene) and rubber-modified poly(p-methylstyrene) identified in this section may be safely used as components of articles...

Unraveling the mystery of natural rubber biosythesis part I: investigation of the composition and growth of in vitro natural rubber using high resolution size exclusion chromatography

USDA-ARS?s Scientific Manuscript database

Monitoring the growth of in vitro natural rubberwas accomplished by high resolution size exclusion chromatography, SEC.Washed rubber particles isolated from H. brasiliensis latex, containing the rubber transferase enzyme, were used to catalyze the polymerization of synthetic isopentenyl pyrophosphat...

Characterization of some selected vulcanized and raw silicon rubber materials

NASA Astrophysics Data System (ADS)

Sasikala, A.; Kala, A.

2017-06-01

Silicone Rubber is a high need of importance of Medical devices, Implants, Aviation and Aerospace wiring applications. Silicone rubbers are widely used in industry, and there are in multiple formulations. A raw and vulcanized silicone rubber Chemical and Physical structures of particles was confirmed and mechanical strength has been analyzed by FTIR spectroscopy. Thermal properties studied from Thermo Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) analysis. Activation energy of the rubber materials were calculated using Broido method, Piloyon-Novikova relation and coats-Red fern methods.

Effect of heating rate on toxicity of pyrolysis gases from some elastomers

NASA Technical Reports Server (NTRS)

Hilado, C. J.; Kosola, K. L.; Solis, A. N.

1977-01-01

The effect of heating rate on the toxicity of the pyrolysis gases from six elastomers was investigated, using a screening test method. The elastomers were polyisoprene (natural rubber), styrene-butadiene rubber (SBR), ethylene propylene diene terpolymer (EPDM), acrylonitrile rubber, chlorosulfonated polyethylene rubber, and polychloroprene. The rising temperature and fixed temperature programs produced exactly the same rank order of materials based on time to death. Acrylonitrile rubber exhibited the greatest toxicity under these test conditions, and carbon monoxide was not found in sufficient concentrations to be the primary cause of death.

Research on the Dielectric Properties of Nano-ZnO/Silicone Rubber Composites

NASA Astrophysics Data System (ADS)

Wang, Fei-feng; Yan, Dan-dan; Su, Yi; Lu, Yu-feng; Xia, Xiao-fei; Huang, Hui-min

2017-09-01

The samples of 1%, 2%, 3% and 4% Zinc Oxide (ZnO) nano-composite silicone rubber were prepared by mechanical method. The dielectric properties of each sample were measured by dielectric spectroscopy. The experimental results showed that the dielectric constant of the silicone rubber composite increases with the increase of the content of nano-ZnO. The breakdown test results showed that with the increase of the content of nano-ZnO, the breakdown strength of silicone rubber composites increased first and then decreased. The breakdown test results indicate that the nano-ZnO can reduce the breakdown strength of silicone rubber. The hydrophobic test results showed that nano-ZnO will reduce the hydrophobic of silicone rubber.

Method for co-processing waste rubber and carbonaceous material

DOEpatents

Farcasiu, Malvina; Smith, Charlene M.

1991-01-01

In a process for the co-processing of waste rubber and carbonaceous material to form a useful liquid product, the rubber and the carbonaceous material are combined and heated to the depolymerization temperature of the rubber in the presence of a source of hydrogen. The depolymerized rubber acts as a liquefying solvent for the carbonaceous material while a beneficial catalytic effect is obtained from the carbon black released on depolymerization the reinforced rubber. The reaction is carried out at liquefaction conditions of 380.degree.-600.degree. C. and 70-280 atmospheres hydrogen pressure. The resulting liquid is separated from residual solids and further processed such as by distillation or solvent extraction to provide a carbonaceous liquid useful for fuels and other purposes.

Dynamic mechanical analysis of waste tyre rubber filled brake friction composite materials

NASA Astrophysics Data System (ADS)

Rathi, Mukesh Kumar; Singh, Tej; Chauhan, Ranchan

2018-05-01

In this research work, the dynamic mechanical properties of waste tyre rubber filled friction composites were studied. Four friction composites with varying amount of waste rubber (0, 4, 8, 12 wt.%) and barium sulphate (38, 42, 46, 50 wt.%) were designed and fabricated as per industrial norms. Dynamic mechanical analysis has been carried out to characterize the storage modulus, loss modulus and damping factor of the fabricated friction composite. Experimental results indicated that storage modulus decreases with increasing waste rubber content up to particular loading (4 wt.%), and after that it increases with further loading. The loss modulus of the composites increases steadily with increasing waste rubber content whereas, damping factor remain maximum for 12 wt.% waste rubber filled friction composites.

High damping properties of magnetic particles doped rubber composites at wide frequency

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

Tian, Ye, E-mail: schtiany@163.com; College of Material Science and Engineering, North University of China, Taiyuan 030051; Liu, Yaqing, E-mail: lyq@nuc.edu.cn

Highlights: ► A new kind of permanent magnetic rubber was prepared. ► The microstructure and magnetic properties were investigated. ► The mechanical and damping properties were discussed. ► The new material is expected to be an isolator material to a changed frequency. - Abstract: A new kind of rubber composite was prepared by doping SrFe{sub 12}O{sub 19} nanoparticles coated with silane coupling agents (Si-69) into nitrile butadiene rubber (NBR) matrix, which was characterized by the scanning electron microscopy and X-ray spectroscopy. The results showed that the SrFe{sub 12}O{sub 19} nanoparticles were well dispersed in rubber matrix. Furthermore, the mechanical andmore » magnetic properties of the rubber composites were investigated, in which the high tensile strength (15.8 MPa) and high saturation magnetization (22.9 emu/g) were observed. What is more, the high loss factor of the rubber composites was also obtained in a wide frequency range (0–100 Hz) at high loading (80 phr). The result is attributed to that the permanent magnetic field in rubber nanocomposites can absorb shock energy. These results indicate that the new kind of permanent magnetic rubber is expected to be a smart isolator material, in which the isolator will be able to adapt to a changed frequency.« less

Properties of Vulcanized Polyisoprene Rubber Composites Filled with Opalized White Tuff and Precipitated Silica

PubMed Central

Zeković, Ivana; Marinović-Cincović, Milena

2014-01-01

Opalized white tuff (OWT) with 40 μm average particle size and 39.3 m2/g specific surface area has been introduced into polyisoprene rubber (NR). Their reinforcing effects were evaluated by comparisons with those from precipitated silica (PSi). The cure characteristic, apparent activation energy of cross-link (E ac) and reversion (E ar), and mechanical properties of a variety of composites based on these rubbers were studied. This was done using vulcanization techniques, mechanical testing, and scanning electron microscopy (SEM). The results showed that OWT can greatly improve the vulcanizing process by shortening the time of optimum cure (t c90) and the scorch time (t s2) of cross-linked rubber composites, which improves production efficiency and operational security. The rubber composites filled with 50 phr of OWT were found to have good mechanical and elastomeric properties. The tensile strengths of the NR/OWT composites are close to those of NR/PSi composites, but the tear strength and modulus are not as good as the corresponding properties of those containing precipitated silica. Morphology results revealed that the OWT is poorly dispersed in the rubber matrix. According to that, the lower interactions between OWT and polyisoprene rubber macromolecules are obtained, but similar mechanical properties of NR/OWT (100/50) rubber composites compared with NR/PSi (100/50) rubber composites are resulted. PMID:24672391

Involvement of Two Latex-Clearing Proteins during Rubber Degradation and Insights into the Subsequent Degradation Pathway Revealed by the Genome Sequence of Gordonia polyisoprenivorans Strain VH2

PubMed Central

Hiessl, Sebastian; Schuldes, Jörg; Thürmer, Andrea; Halbsguth, Tobias; Bröker, Daniel; Angelov, Angel; Liebl, Wolfgang; Daniel, Rolf

2012-01-01

The increasing production of synthetic and natural poly(cis-1,4-isoprene) rubber leads to huge challenges in waste management. Only a few bacteria are known to degrade rubber, and little is known about the mechanism of microbial rubber degradation. The genome of Gordonia polyisoprenivorans strain VH2, which is one of the most effective rubber-degrading bacteria, was sequenced and annotated to elucidate the degradation pathway and other features of this actinomycete. The genome consists of a circular chromosome of 5,669,805 bp and a circular plasmid of 174,494 bp with average GC contents of 67.0% and 65.7%, respectively. It contains 5,110 putative protein-coding sequences, including many candidate genes responsible for rubber degradation and other biotechnically relevant pathways. Furthermore, we detected two homologues of a latex-clearing protein, which is supposed to be a key enzyme in rubber degradation. The deletion of these two genes for the first time revealed clear evidence that latex-clearing protein is essential for the microbial utilization of rubber. Based on the genome sequence, we predict a pathway for the microbial degradation of rubber which is supported by previous and current data on transposon mutagenesis, deletion mutants, applied comparative genomics, and literature search. PMID:22327575

Sulfur Mustard Penetration of Thermoplastic Elastomers

DTIC Science & Technology

2008-10-01

blend of polypropylene and finely dispersed, highly vulcanised EPDM rubber [4]. However its exact composition is a trade secret. The Santoprene grade... rubber or silicone rubber . Compared to thermoplastic elastomers, these thermosetting elastomers are expensive and difficult to process. Therefore a...the last few decades, CBR respirators have generally been manufactured from either butyl rubber (as in the British and Australian S10), or silicone

Thermomyces lanuginosus STm: a source of thermostable hydrolytic enzymes for novel application in extraction of high-quality natural rubber from Taraxacum kok-saghyz (rubber dandelion)

USDA-ARS?s Scientific Manuscript database

Hydrolytic enzymes from a newly isolated strain of the thermophilic fungus Thermomyces lanuginosus were used to extract rubber from Taraxacum kok-saghyz commonly known as rubber (or Russian or Kazak(h)) dandelion. The fungus was isolated from garden soil and identified as Thermomyces lanuginosus STm...

A new mechanism for selective adsorption of rubber on carbon black surface caused by nano-confinement in SBR/NBR solution

NASA Astrophysics Data System (ADS)

Kawazoe, Masayuki

A novel mechanism of selective adsorption of rubber molecules onto carbon black surface in a binary immiscible rubber blend solution has been proposed in this dissertation. The phenomenon leads to uneven distribution of carbon black to the specific polymer in the blend and the obtained electrically conductive composite showed drastic reduction of percolation threshold concentration (PTC). The mechanism and the feature of conductive network formation have much potential concerning both fundamental understanding and industrial application to improve conductive polymer composites. In chapter I, carbon black filled conductive polymer composites are briefly reviewed. Then, in chapter II, a mechanism of rubber molecular confinement into carbon black aggregate structure is introduced to explain the selective adsorption of a specific rubber onto carbon black surface in an immiscible rubber solution blend (styrene butadiene rubber (SBR) and acrylonitrile butadiene rubber (NBR) with toluene or chloroform). Next, in chapters III and IV, polymers with various radius of gyration (Rg) and carbon blacks with various aggregate structure are examined to verify the selective adsorption mechanism. Finally, in chapter V, the novel mechanism was applied to create unique meso-/micro-unit conductive network in carbon black dispersed SBR/NBR composites.

Rubber friction: role of the flash temperature

NASA Astrophysics Data System (ADS)

Persson, B. N. J.

2006-08-01

When a rubber block is sliding on a hard rough substrate, the substrate asperities will exert time-dependent deformations of the rubber surface resulting in viscoelastic energy dissipation in the rubber, which gives a contribution to the sliding friction. Most surfaces of solids have roughness on many different length scales, and when calculating the friction force it is necessary to include the viscoelastic deformations on all length scales. The energy dissipation will result in local heating of the rubber. Since the viscoelastic properties of rubber-like materials are extremely strongly temperature dependent, it is necessary to include the local temperature increase in the analysis. At very low sliding velocity the temperature increase is negligible because of heat diffusion, but already for velocities of order 10-2 m s-1 the local heating may be very important. Here I study the influence of the local heating on the rubber friction, and I show that in a typical case the temperature increase results in a decrease in rubber friction with increasing sliding velocity for v>0.01 m s-1. This may result in stick-slip instabilities, and is of crucial importance in many practical applications, e.g. for tyre-road friction and in particular for ABS braking systems.

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.

Mechanical properties and durability of crumb rubber concrete

NASA Astrophysics Data System (ADS)

Chylík, Roman; Trtík, Tomáš; Fládr, Josef; Bílý, Petr

2017-09-01

This paper is focused on concrete with admixture of rubber powder, generally called crumb rubber concrete (CRC). The inspiration was found in Arizona, where one of the first CRCs has been created. However, Arizona has completely different climates than Central Europe. Could we use the crumb rubber concrete on construction applications in the Central European climate too? The paper evaluates the influence of the rubber powder on material characteristics and durability of CRC. CRCs with various contents of fine and coarse crumb powder were compared. The tested parameters were slump, air content, permeability, resistance of concrete to water with deicing chemicals, compressive and splitting tensile strength. The tests showed that workability, compressive strength and permeability decreased as the amount of rubber increased, but the air content increased as the rubber content increased. Photos of air voids in cement matrix from electron microscope were captured. The results of laboratory tests showed that admixture of rubber powder in concrete could have a positive impact on durability of concrete and concurrently contribute to sustainable development. Considering the lower compressive strength, CRC is recommended for use in applications where the high strength of concrete is not required.

The optimum content of rubber ash in concrete: flexural strength

NASA Astrophysics Data System (ADS)

Senin, M. S.; Shahidan, S.; Shamsuddin, S. M.; Ariffin, S. F. A.; Othman, N. H.; Rahman, R.; Khalid, F. S.; Nazri, F. M.

2017-11-01

Discarded scrap tyres have become one of the major environmental problems nowadays. Several studies have been carried out to reuse waste tires as an additive or sand replacement in concrete with appropriate percentages of tire rubber, called as rubberized concrete to solve this problem. The main objectives of this study are to investigate the flexural strength performance of concrete when adding the rubber ash and also to analyse the optimum content of rubber ash in concrete prisms. The performance total of 30 number of concrete prisms in size of 100mm x 100mm x 500 mm were investigated, by partially replacement of rubber ash with percentage of 0%, 3%, 5%, 7% and 9% from the volume of the sand. The flexural strength is increased when percentage of rubber ash is added 3% from control concrete prism, RA 0 for both concrete prism age, 7 days and 28 days with value 1.21% and 0.976% respectively. However, for RA 5, RA 7 and RA 9, the flexural strength was decreased compared to the control for both age, 7 days and 28 days. In conclusion, 3% is the optimum content of rubber ash in concrete prism for both concrete age

Optical and Thermal Stability of Oligofluorene/Rubber Luminescent Blend.

PubMed

Barbosa, Camila G; Faez, Roselena; Péres, Laura O

2016-09-01

This paper proposes to obtain homogeneous and stable blends of oligo(9,9-dioctylfluorene)-co-phenylene (OF), a conjugated oligomer with strong tendency of formation of excimers in the solid state, and nitrile rubber (NBR). This rubber protection reduces the formation of polymer excimers in the films. The fluorene oligomer was synthesized via Suzuki reaction and incorporated in the nitrile rubber. The films were formed by spin coating and casting techniques on the proportions of 1, 5, 10, 20 and 50 % (w/w) of OF in the nitrile rubber (NBR). The structural, optical and thermal properties of the films were evaluated with infrared, UV-Vis, fluorescence and thermogravimetry, respectively. The nitrile rubber proved to be essential for the preparation of homogeneous and stable films, since it was not possible to obtain films with only fluorene using the above-mentioned techniques. Furthermore, luminescent properties of OF are unchanged and the excimers formation in the solid state decrease suggesting the efficiency of nitrile rubber as the matrix for making films.

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. © 2014 The Society for Applied Microbiology.

Effect of urea deproteinization on catalytic hydrogenation of natural rubber latex

NASA Astrophysics Data System (ADS)

Cifriadi, A.; Chalid, M.; Puspitasari, S.

2017-07-01

Natural rubber is unsaturated biopolymer which has low resistance to heat, oxygen, and ozone. Chemical modification of natural rubber by catalytic hydrogenation can improve its oxidative property. In this study, the catalytic hydrogenation of natural rubber was investigated in latex phase after reduction of protein content with urea. Hydrogenation of deproteinized natural rubber latex was performed by using diimide which generated insitu from hydrazine hydrate/hydrogen peroxide and catalyst (boric acid, cupric sulfate and cupric acetate) at 70°C for 5 h. The hydrogenation system was stabilized with sodium dodecyl sulphate. The hydrogenation of deproteinized natural rubber (HDPNR) was confirmed by FTIR analysis. The result indicated that cupric sulphate was extremely active catalyst which was showed by the elimination of C=C transmittance bands at 1660 cm-1 on HDPNR spectra and highest degree of hydrogenation. Furthermore, urea deproteinization increased possibility of side reactions during catalytic hydrogenation as seen on the reduction of gel content compared to undeproteinized natural rubber.

General theory of frictional heating with application to rubber friction

NASA Astrophysics Data System (ADS)

Fortunato, G.; Ciaravola, V.; Furno, A.; Lorenz, B.; Persson, B. N. J.

2015-05-01

The energy dissipation in the contact regions between solids in sliding contact can result in high local temperatures which may strongly effect friction and wear. This is the case for rubber sliding on road surfaces at speeds above 1 mm s-1. We derive equations which describe the frictional heating for solids with arbitrary thermal properties. The theory is applied to rubber friction on road surfaces and we take into account that the frictional energy is partly produced inside the rubber due to the internal friction of rubber and in a thin (nanometer) interfacial layer at the rubber-road contact region. The heat transfer between the rubber and the road surface is described by a heat transfer coefficient which depends on the sliding speed. Numerical results are presented and compared to experimental data. We find that frictional heating results in a kinetic friction force which depends on the orientation of the sliding block, thus violating one of the two basic Leonardo da Vinci ‘laws’ of friction.

Compressive Strength and Modulus of Elasticity of Concrete with Cubed Waste Tire Rubbers as Coarse Aggregates

NASA Astrophysics Data System (ADS)

Haryanto, Y.; Hermanto, N. I. S.; Pamudji, G.; Wardana, K. P.

2017-11-01

One feasible solution to overcome the issue of tire disposal waste is the use of waste tire rubber to replace aggregate in concrete. We have conducted an experimental investigation on the effect of rubber tire waste aggregate in cuboid form on the compressive strength and modulus of elasticity of concrete. The test was performed on 72 cylindrical specimens with the height of 300 mm and diameter of 150 mm. We found that the workability of concrete with waste tire rubber aggregate has increased. The concrete density with waste tire rubber aggregate was decreased, and so was the compressive strength. The decrease of compressive strength is up to 64.34%. If the content of waste tire rubber aggregate is more than 40%, then the resulting concrete cannot be categorized as structural concrete. The modulus of elasticity decreased to 59.77%. The theoretical equation developed to determine the modulus of elasticity of concrete with rubber tire waste aggregate has an accuracy of 84.27%.

General theory of frictional heating with application to rubber friction.

PubMed

Fortunato, G; Ciaravola, V; Furno, A; Lorenz, B; Persson, B N J

2015-05-08

The energy dissipation in the contact regions between solids in sliding contact can result in high local temperatures which may strongly effect friction and wear. This is the case for rubber sliding on road surfaces at speeds above 1 mm s(-1). We derive equations which describe the frictional heating for solids with arbitrary thermal properties. The theory is applied to rubber friction on road surfaces and we take into account that the frictional energy is partly produced inside the rubber due to the internal friction of rubber and in a thin (nanometer) interfacial layer at the rubber-road contact region. The heat transfer between the rubber and the road surface is described by a heat transfer coefficient which depends on the sliding speed. Numerical results are presented and compared to experimental data. We find that frictional heating results in a kinetic friction force which depends on the orientation of the sliding block, thus violating one of the two basic Leonardo da Vinci 'laws' of friction.

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.

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