Anionic Polymerization And Properties Of Graft Copolymers Consisting Of Alternating Styrene/Maleimide Copolymer Main Chains And Polyamide 6 Grafts

Polyamide 6 (PA6), usually known as nylon 6, is a versatile material that combines excellent mechanical properties and good resistence to chemicals and solvents, and it owns the largest quality among the five common engineering plastics. But PA6 has a low Tg (about 320K), a low heat distortion temperature and high moisture absorption, which limit its application in many fields. Thus it can be modified by physical or chemical route. When using the later way, one can choose blocking or grafting method to prepare functional polymers, such as antistatic PA6, flame retardant PA6 or impact resistance PA6.It is well known that the polymers containing N-substituted maleimides and their derivatives can be classified as polyimides, important high performance engineering plastics, being a class of rigid polymers because of the imide rings in the backbone. They are known to be resistant to high temperature (Tg≥500K) and solvents, with high dimensional stability.This paper focused on the synthesis of a new type of graft PA6, which contained alternating styrene/maleimide copolymer main chains and PA6 grafts, by anionic polymerization. The main chains were copolymerized with different ratio of styrene, N-phenyl maleimide and N - (4 - hydroxyphenyl) maleimide. Then styrene/maleimide copolymers with acylated caprolactam (ACL) pendants were then used to act as macroactivators for the polymerization of moltenε-caprolactam (CL), at the existence of sodium caprolactam. Because of the low activating energy for the initial nucleophilic attack of caprolactam anion on the N-acylated caprolactam, the polymerization took place in a few minutes. For comparison, pure PA6 were also prepared, using microactivator of tolylene diisocyanate.The macroactivators were characterized with 1H-NMR. And the thermal property, dimensional stability, crystallinity, and solvent resistant ability of the graft PA6 were studied, using DSC, TGA, XRD, water absorption measurement, and solubility experiment. Compared with pure PA6, graft PA6 studied in this paper displays better thermal behaviors, better dimensional stability and better solvent resistance, and the existence of styrene/maleimide copolymers does not change the crystallinity structure of the PA6 matrix.