Compatibilization of nylon 6/ABS blends using glycidyl methacrylate methyl methacrylate copolymers

Blends of nylon 6 with acrylonitrile/butadiene/styrene (ABS) materials and with its styrene/acrylonitrile copolymer (SAN) matrix were prepared using a series of glycidyl methacryIate/methyl methacrylate (GMA/MMA) copolymers as compatibilizing agents. These copolymers are miscible with SAN and the epoxide unit in GMA is capable of reacting with the polyamide end groups. This copolymer thus has the potential to form graft copolymers at the polyamide/SAN interface during melt processing. This study focuses on the effects of functionality and concentration of the compatibilizer on the rheological, morphological, and mechanical properties of these blends. In general, incorporation of this compatibilizer does not significantly improve the impact properties of nylon 6/ABS blends. In these blends, nylon 6 was always the continuous phase; TEM photomicrographs indicate that incorporation of the compatibilizer results in two distinct populations of ABS domains: large agglomerates, and small dispersed particles. The agglomerates become larger with increasing GMA content in the compatibilizer and result in a non-uniform distribution of rubber particles within the nylon 6 matrix. Torque rheometry was employed to identify the reaction mechanisms that may be responsible for the development of such morphologies. These experiments demonstrate that the cause of the poor ABS dispersion is the difunctionality of the nylon 6 end groups with respect to the epoxide group of GMA, which leads to crosslinking-type reactions. (C) 1998 Elsevier Science Ltd. All rights reserved.