Toughening and brittle‐tough transition in blends of an amorphous polyamide with a modified styrene/ethylene‐butylene/styrene triblock copolymer

Abstract

Abstract Amorphous polyamide (aPA)/maleated styrene/ethylene‐butylene/styrene triblock copolymer (mSEBS) blends with a mSEBS content up to 25% were obtained in the melt state with the aim of toughening the notch sensitive pseudoductile matrix, and of studying the parameters that influence the morphology that leads to the brittle/tough transition. The increase in the T g of the rubbery phase, which depended on the maleinized copolymer content, indicated the presence of reacted copolymers. These copolymers should decrease the interfacial tension, thus allowing the presence of a fine dispersed particle size. The impressive (27‐fold) toughness increase observed, which is among the largest observed in toughened blends, took place at 15% mSEBS content. The critical interparticle distance (τ c ) of the blends was smaller than that of polyamide 6 (PA6)/mSEBS blends tested at the same conditions. Having ruled out the possible influence of other parameters, the lower τ c of the aPA/mSEBS blends of this study is attributed to their higher interfacial adhesion that was inferred by the calculation of the solubility parameters and by the measured interfacial toughness. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers