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Abstract:
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This thesis presents the findings of a study on incorporating vanous
thermoset resins into natural rubber for property improvement. Natural rubber
is an important elastomer with the unique attribute of being a renewable
agricultural product. The study was undertaken to investigate the extent to
which the drawbacks of natural rubber, especially its poor thermal and oil
resistance propel1ies could be nullified by blending with common thermoset
resins. A thorough and comparative understanding of the perfonnance of
different resins from this viewpoint will be beneficial for both natural IUbber
processors and consumers. In this study the thennoset resins used were epoxy
resin, phenolics, epoxidised phenolics and unsaturated polyester resin.The resins were incorporated into NR during compounding and their
effects on the properties of NR were studied after vulcanization. Properties
were studied for both gum and filled N R compounds. The important properties
studied are cure characteristics, mechanical properties, ageing propel1ies,
thermal propel1ies, crosslink density and extractability. Characterization studies
were also conducted using FTIR, TGA and DSC.Improvement in mechanical properties was noticed in many cases. The
results show that most resins lead to a reduction in the cure time of NR. The
perfonnance of epoxy resin is most noticeable in this respect. Mechanical
properties of the modified IUbber show maximum improvement in the case of
epoxidised novolacs. Most resins are seen to improve the thermal and oil
resistance propel1ies of NR. Epoxy novolacs show maximum effect in this
respect also. However the presence of tillers is found to moderate the positive
effects of the thermoset resins considerably. |