The role of matrix molecular weight in rubber toughened nylon 6 blends .3. Ductile-brittle transition temperature

Izod impact strength was measured as a function of temperature for blends of nylon 6 with maleated and non-maleated styrene-hydrogenated butadiene-styrene triblock copolymers, SEBS, and ethylene/propylene random copolymers, EPR, to determine the effects of polyamide molecular weight, rubber type, and rubber particle size on the ductile-brittle transition temperature. In general, the ductile-brittle transition temperature decreases as the molecular weight of the nylon 6 matrix increases when compared at either constant maleic anhydride content of the rubber or at constant rubber particle size. Blends based on SEBS type elastomers with a standard styrene content never attain ductile-brittle transition temperatures below -20 degrees C; whereas, blends generated with EPR type rubbers or a block copolymer of low styrene content can reach values as low as -50 degrees C. This difference in ductile-brittle transition temperature is related to the low temperature mechanical properties of the rubber phase. Copyright (C) 1996 Elsevier Science Ltd.