Aiming the development of high toughness polymeric materials, poly(butadiene-co-acrylonitrile) rubbers (NBRs) with acrylonitrile (AN) contents varying from 32.9 to 45.7% were incorporated to poly(styrene-co-acrylonitrile) (SAN) by monoscrew extrusion followed by injection molding. Addition of NBR resulted in significant improvements in the impact strength and the elongation at break, that were strongly influenced by the blend composition, the AN contents and the NBR melt viscosities, but the tensile strength was slightly decreased. The best impact strength results (157.1 ± 3.7J/m) were obtained with a 70/30 (%w/w) SAN/NBR blend using NBR with 33.1% of AN and Mooney viscosity of 51 ML 1+4 (100°C), being ca. 700% higher than the values for pure SAN (22.4 ± 1.1J/m). Scanning electron micrographs (SEM) from fracture surfaces revealed homogeneously dispersed spherical elastomeric domains, and the appearance of yielding and/or crazing processes for all blends. The size of NBR domains decreased as the AN content increased, while the number of NBR domains decreased as the melt viscosity increased.
Blends; SAN; NBR; tenacification; mechanical properties
