Analysis of Glass Transition Temperatures and Mechanical Properties of Epoxy Modified Natural Rubber

摘要

The glass transition temperature T-g and mechanical properties of diglycidyl ether of bisphenol A (DGEBA) toughened with two different types of modified natural rubber with and without added clay particles were studied. Poly(etheramine) was used as the curing agent. Two modified natural rubbers, poly(methyl methacrylate) (PMMA) grafted natural rubber (MG30) and liquid epoxidised natural rubber (LENR) were studied at different amounts. The addition of modified natural rubber increased the value of T-g compared to the neat epoxy. It was found that the use of modified natural rubber lowered the hardness value of the epoxy modified system compared to neat epoxy. Generally, there was no significant difference in T-g value and mechanical properties between the epoxy-LENR and epoxy-MG30 systems. The value of Young's modulus and flexural modulus in this work were significantly different. It was observed that the higher amount of rubber content in the material gave larger size rubber particles, hence, lowering the tensile Young's modulus and flexural modulus. The adhesion of rubber with epoxy seemed to be poor when using a larger amount of rubber content. The addition of clay nanoparticles (Cloisite Na) increased the T-g and mechanical properties of the system not only relative to the natural rubber modified epoxy, but also for the neat epoxy. In these hybrid modifier systems of clay/modified natural rubber, a significant enhancement in mechanical properties relative to neat epoxy was noticeable.