Cure characteristics, thermal and mechanical properties of natural rubber/synthetic rubber blends with and without compatibilizer

Supat Moolsin

Authors

Supat Moolsin Department of Chemistry, Faculty of Science, Rangsit University, Patumthani, 12000, Thailand

Keywords:

rubber blend, natural rubber, synthetic rubber, compatibilizer, epoxidized natural rubber, Ultrablend-6000

Abstract

In this study, the effects of compatibilizer loading on the cure characteristics, thermal and mechanical properties of natural rubber (NR)/synthetic rubber (SR) blends have been investigated. NR was molten and mixed with six synthetic rubbers (butadiene rubber, chloroprene rubber, ethylene-propylene diene rubber, isoprene rubber, nitrile rubber and styrene butadiene rubber) with varied NR/SR weight ratios (100/0, 75/25, 50/50, 25/75 and 0/100) and compatibilizer loadings (0-5 parts per hundred of rubber, phr) on a two roll mill at 70°C. The results obtained from differential scanning calorimetry revealed that most of the NR/SR blends both with and without compatibilizer exhibited two glass transition temperatures, indicating that the inclusion of compatibilizers (ENR-25, ENR-50 and Ultrablend-6000) did not improve the compatibility between NR and SRs. However, they could reduce the cure time by 20-50%, as compared to the neat rubber blends, suggesting the reduction in the production energy. Tensile strength of some 50/50 rubber blends with a specific amount and type of compatibilizer improved significantly. Natural rubber/butadiene rubber with 5 phr of ENR-25, natural rubber/chloroprene rubber with 5 phr of ENR-50 and natural rubber/isoprene rubber with 5 phr of Ultrablend-6000 were great examples in terms of improving the mechanical properties.

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