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1 Introduction Elastomeric materials have a wide range of applications due to their inherent reversible deformation characteristics. Natural rubber is a prototype of an elastomer. Due to the high structural regularity of natural rubber, it tends to

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Abstract  

Some synergistic effects of antioxidants in natural rubber were investigated considering results obtained by differencial scanning calorimetry (DSC). Rubber formulations were obtained with mixtures of diaminic(DPPD, IPPD, HPPD) and monoaminic (ADPA, PBN) stabilizers and evaluated. The samples containing the mixture diamine/ADPA stabilizers showed synergistic effects while, for those containing diamine/PBN, no effect was observed. Additionally, the diffusion constants determined by use of vulcanized rubber disks confirmed the molar mass dependence of the stabilizer.

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Abstract  

The thermal behavior of chitosan (CS)/natural rubber latex (NRL) blends has been studied by thermogravimetry (TG) and differential scanning calorimetry (DSC). Decomposition behavior of CS changes with the addition of NRL. The effect of blend composition on the amount of residue remaining at various temperatures has been studied. Activation energies of degradation have been calculated using Horowitz-Metzger equation. From the activation energy values, it is found that among the series of the blend compositions, CS15NRL85 exhibits better thermal stability. DSC studies reveals that the CS/NRL blends are thermodynamically incompatible. This is evident from the presence of two glass transitions, corresponding to CS and NRL phases in the blend.

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Journal of Thermal Analysis and Calorimetry
Authors: S. Ľalíková, M. Pajtášová, M. Chromčíková, M. Liška, V. Šutinská, M. Olšovský, D. Ondrušová, and S. C. Mojumdar

) spectrometer Tensor 27 in the region 4000–400 cm −1 with a resolution of 4 cm −1 . Preparation of natural rubber (NR)/clay composites Natural rubber SMR-20 was used as the elastomeric matrix. Carbon black N660 was used as

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injection moulding process has been somewhat neglected and the production relied mostly upon experience [ 2 , 7 , 8 ]. Although, natural rubber (NR) is one of the most widely used rubbers to produce diversified injection-moulded rubber products, the

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investigated as a bioactive material for enhancing bone regeneration and vascular prostheses [ 10 , 17 , 18 ]. The natural rubber latex (NR) obtained from the Hevea brasiliensis trees [ 19 ] is essentially composed by poly cis-1,4-isoprene, besides

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Abstract  

Epoxidized natural rubbers (ENRs) with different extents of epoxidation (B) were prepared under various reaction conditions. The effects of the amount of H2O2 and the reaction time on B are discussed. The glass transition temperature T g, the thermal degradation temperature and the activation energy of thermal degradation of the ENRs increase with B. The results indicate that the thermal stability of the ENRs increases with B.

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In view of the lack of precise experimental data in the literature concerning the determination of a definedTg value for natural rubber (NR) and the differences when such data are given, a reference definition ofTg(Vo) is offered and a procedure for obtaining it described in detail.

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Scientometrics
Authors: Narongrit Sombatsompop, T. Markpin, E. Wimolmala, P. Ratchatahirun, N. Premkamolnetr, B. Boonradsamee, and W. Yochai

Abstract  

This article investigated contributions of natural rubber (NR) research through research articles and patents in Science Citation Index Expanded (SCI-Expanded) and SCOPUS databases and related the results with productivity-export volumes during 2002–2006. 1,771 research papers and 5,686 patents on “natural rubber” were retrieved from the databases. The results revealed that the top five countries produced the NR raw material by the order of productivity volumes were Thailand, Indonesia, Malaysia, Vietnam and China whereas those produced the synthetic rubber were the United States, China, Japan, Russia and Germany. Among the top three countries for NR production, Malaysia became a NR producer for its own use, whereas Thailand and Indonesia still had higher export volumes. Research articles and patents on natural rubber had contribution shares of about 20.9% and 47.5% of all rubber publications, respectively. The patents on natural rubber were found to increase with time while the research articles remained unchanged. Journal of Applied Polymer Science was the most preferable for publishing the research papers on rubbers. Eight countries ranked in the top countries for contributing the research articles on natural rubber were the United States, India, Malaysia, France, Germany, Thailand, Japan and China, similar country distributions being also found for research articles on synthetic styrene-butadiene rubber except for Thailand and Malaysia. No linear relationship between the productivity-export volume and research publication number was observed, but the results implied that the growth rate for commercializing the rubber was greater than that for research and development of natural rubber. Most NR research works focused on neat NR, which was contributed the most by USA while NR blend and NR composite papers were mainly published by Indian researchers.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: C. V. Chaudhari, Y. K. Bhardwaj, and S. Sabharwal

Summary  

Grafting ofmethyl methacrylate (MMA) on radiation crosslinked natural rubber (NR) film has been investigated by mutual radiation grafting. The effect of experimental parameters like radiation dose, dose-rate, additives like acids and inorganic salts, solvents, monomer concentration, cross-linking density of the natural rubber film on the grafting extent has been studied.From the kinetic studies, a kinetic equation showing almost parabolic and linear dependence of grafting on concentration and dose rate, respectively, was deduced.Preliminary thermal stability studies of grafted films indicated that grafting of MMA does not enhance the thermal stability of NR.

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