Characterization and properties of epoxidised natural rubber (ENR-50) / Ethylene Vinyl Acetate (EVA) blends
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Date
2007
Authors
Mohamad, Zurina
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Abstract
The effect of blend ratio, dynamic vulcanization, electron beam irradiation and the combination of irradiation and crosslinking agent on the properties of epoxidised natural rubber/ ethylene vinyl acetate (ENR-50/EVA) blends were investigated. The dynamic vulcanization were prepared using sulphur and dicumyl peroxide (DCP) as crosslink agent, while trimethylolpropane triacrylate (TMPTA), tripropyleneglycol diacrylate (TPGDA) and N,N-m pehylenebismaleimide (HVA-2) were crosslinking agents chosed to combined with irradiation. Blends were prepared by melt mixing in an internal mixer, Haake Rheomix Polydrive R600/610 at temperature and rotor speed of 120ÂșC and 50 rpm respectively. Blend systems were covering various compositions viz. 0/100, 20/80, 40/60, 50/50, 60/40, 80/20 and 100/0 of ENR-50/EVA. Results showed that the tensile properties and thermal stability increased with the increases in EVA content due to it superior properties than ENR-50. Results on dynamic mechanical properties revealed that the blend was compatible at all blend ratios. Meanwhile, dynamic vulcanization has increased tensile strength, thermal properties and gel content. These findings follow the theory stated that the formation of crosslinking increases the molecular entanglement in the rubber phase. Formation of finer vulcanized rubber particles due to the presence of crosslinks improved stability of the morphology and subsequently increased the blend properties. However, in the case of DCP, apart from the crosslinking formation in rubber phase, the chain scission has also developed on ethylene vinyl acetate (EVA). The introduction of electron beam irradiation on ENR-50/EVA (50/50) blends at different dosage viz. 20,40,60 and 100 kGy has enhance the irradiation-induced crosslinking. Irradiation-induced crosslinking increased with increase in irradiation dose and lead to the improvement in tensile properties, thermal properties and compatibility of the blend. The incorporation of crosslinking agents such as TMPTA, TPGDA and HVA-2 has further enhanced the irradiation-induced crosslinking and lead to the improvement of tensile strength, thermal and dynamic mechanical properties. TMPTA was found to be the most effective in promoting irradiation-induced crosslinking of ENR-50/EVA blends.
Description
PhD
Keywords
Chemical science , Epoxidised natural rubber , Ethylene Vinyl Acetate