Synthesis, properties, and biodegradability of three-branched copolyamide (4/6)

摘要

Previous studies on polyamide 4, excellent properties, functionalities, and biodegradation in natural condition have been shown. In this study, three-branched (star-shaped) copolyamides constituted of polyamide 4 and polyamide 6 constitutional unit were synthesized by anionic ring-opening copolymerization of 2-pyrrolidone with epsilon-caprolactam. The thermal and mechanical properties and the biodegradability of the obtained copolyamides have been systematically investigated. The weight-average molecular weight of the copolyamides was as high as tens of thousands (M(w)10-80 x 10(3) g/mol). The composition of the copolyamides was approximately in accord with the monomer feed ratio, thereby being controllable. The thermal and mechanical properties changed readily as the composition was varied (T(m)146-266 degrees C, Delta H(m)10-70 J/g,T(d)278-369 degrees C, tensile strength 28-64 MPa, elongation at break 80-750%). The copolyamide having 2-pyrrolidone unit of 96-51 mol% exhibited biodegradability by an activated sludge. The biodegradation of the copolyamide proceeded uniformly without disproportion in constitutional unit.