EFFECT OF MORPHOLOGY ON THE BRITTLE-DUCTILE TRANSITION OF POLYMER BLENDS - 6 - INFLUENCE OF RUBBER PARTICLE SPATIAL-DISTRIBUTION ON THE TOUGHENING AND STIFFENING EFFICIENCY OF POLY(VINYL CHLORIDE) NITRILE RUBBER BLENDS

The influence of rubber particle spatial distribution on the toughenin g and stiffening efficiency of poly(vinyl chloride) (PVC)/nitrile rubb er (NBR) blends is quantitatively studied. Blends with the pseudonetwo rk morphology or the morphology of well-dispersed rubber particles are used to elucidate the influence. The spatial distribution and matrix ligament thickness considerably affect the impact strengths of PVC/NBR blends. On the other hand, the tensile modulus of the blends is a fun ction of rubber content but not of particle spatial distribution. Quan titative analysis shows that the modulus for the blend with the pseudo network morphology is much higher than that for the blend with the mor phology of well-dispersed rubber particles for the same values of rubb er particle size, size distribution and high impact strength. The depe ndence of toughening and stiffening efficiency on the spatial distribu tion is stronger than on the matrix ligament thickness. The pseudonetw ork morphology is thus demonstrated to be very efficient in generating PVC/NBR blends simultaneously with high toughness and high stiffness. (C) 1998 Elsevier Science Ltd. All rights reserved.