Properties of compatibilized nylon 6/ABS blends: Part II. Effects of compatibilizer type and processing history

Abstract

The effects of processing history on the morphological, rheological, and mechanical behavior of blends of nylon 6 and acrylonitrile–butadiene–styrene (ABS) using an imidized acrylic (IA) polymer and a styrene/acrylonitrile/maleic anhydride (SANMA) terpolymer as compatibilizing agents have been investigated. Both compatibilizers yield blends that are super tough at room temperature; however, there are distinct differences in their effects on low temperature impact properties. For blends containing the IA polymer and a 1:1 ratio of nylon 6 to ABS, the low-temperature ductility compromises multiple extrusion steps. In general, the ductile-to-brittle transition temperature of blends containing high IA contents increase more rapidly with the number of extrusions than at lower IA contents. High IA content blends exhibited significant changes in morphology with increased number of extrusion steps; some of the ABS domains became larger, leading to a poorer dispersion of rubber particles. The ductile-to-brittle transition temperature is relatively insensitive to the number of extrusions for blends with less than 1wt.% IA content or a higher ratio of nylon 6 to ABS. The morphology and low-temperature toughness of blends containing the SANMA terpolymer were generally unaffected by the number of extrusion passes during melt processing. The differences in low temperature toughness with respect to the processing history appear to stem from differences in the reactive nature of these two types of compatibilizers. Blends containing the IA polymer developed higher melt viscosities than blends containing the SANMA polymer (particularly at higher IA contents), since the nylon 6/IA reaction appears to continue with increasing processing time, whereas the nylon 6/SANMA reaction does not. Potential causes for these fundamental differences in blend rheology are considered in terms of the reactive functionality of the IA versus SANMA compatibilizer. When issues of processability, regrind, and recycling are considered, the SANMA material is a more attractive compatibilizer than the IA polymer, particularly at higher compatibilizer contents.