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ABSTRACT:The velocity of vulcameter torque change during the vulcanization of natural rubber consists of two increasing and decreasing stages. The vulcanization process in the stage of velocity increasing is not a simple reaction, and can be expressed in an equation␣ , which is different from the famous equation of] deduced by Coran, the value of K 1 1/␣ in the former can be used as a rate constant to calculate the value of activation energy (E 1 ) according to the Arrhenius equation. The vulcanization process in the stage of velocity decreasing consists of two firstorder reactions, and can be expressed in a kinetic equation of ln(M H Ϫ M t ) ϭ lnB Ϫ K(t Ϫ t dis ). The time (t p ) at which the torque change reaches to the maximum velocity (V m ) is corresponding to the time (t dis ) suggested by Coran.

ABSTRACT:The effects of pH value of reaction system, reaction time, and reaction temperature on the chlorination reaction in the preparation of chlorinated natural rubber (CNR) from natural rubber latex were discussed. It has been found from the thermal analysis that the thermal degradation of CNR in nitrogen is a one-step reaction, and 30% carbonide with a stable structure remained at 360 to 700°C; whereas the thermo-oxidative degradation of CNR in air is a multistep reaction, and the thermal degradation ratio reaches to 100% at 560°C.

Carbon black incorporated natural rubber/epoxidized natural rubber composites with enhanced microwave absorption capacity have been designed by a novel approach of compatibility-tuned nanoparticles distribution in co-continuous rubber blends.

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