Authors:Wisdom Okechukwu Egbujuo, Placid Ikechukwu Anyanwu, and Henry Chinedu Obasi
1 Introduction Elastomeric materials have a wide range of applications due to their inherent reversible deformation characteristics. Naturalrubber is a prototype of an elastomer. Due to the high structural regularity of naturalrubber, it tends to
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.
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.
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 naturalrubber (NR)/clay composites
Naturalrubber SMR-20 was used as the elastomeric matrix. Carbon black N660 was used as
injection moulding process has been somewhat neglected and the production relied mostly upon experience [ 2 , 7 , 8 ]. Although, naturalrubber (NR) is one of the most widely used rubbers to produce diversified injection-moulded rubber products, the
Authors:R. Simoes, M. Rodriguez-Perez, J. de Saja, and C. Constantino
investigated as a bioactive material for enhancing bone regeneration and vascular prostheses [ 10 , 17 , 18 ].
The naturalrubber latex (NR) obtained from the Hevea brasiliensis trees [ 19 ] is essentially composed by poly cis-1,4-isoprene, besides
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 Tg, 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.
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.
Authors:Narongrit Sombatsompop, T. Markpin, E. Wimolmala, P. Ratchatahirun, N. Premkamolnetr, B. Boonradsamee, and W. Yochai
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
Authors:C. V. Chaudhari, Y. K. Bhardwaj, and S. Sabharwal
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.