Physical Properties of Polyurethane Modified with Poly(m-Phenylene Isophthalamide)

Abstract

A segment of block copolymers with poly(m-phenylene isophthalamide) (PmIA) length was prepared. The block copolymers were prepared using various molecular weights of polytetramethylene glycols (PTMG) as the soft segment, and 4,4′-diphenylmethane diisocyanate (MDI), 1,4-butane diol (BD), and aromatic diamineterminated PmIA as the hard segment. The block copolymers exhibited soft-segment crystallization when a PTMG greater than 2000M, was used. The glass transition temperature, Tgs , of these block copolymers progressively shift to lower temperatures (below 0°C) as the chain length of the soft segment was increased and the glass transition temperature. Tgh , of these block copolymers shift to higher temperatures (up 0°C) as the chain length of hard segment was increased. The stress-strain and stress-relaxation behaviors of block copolymers were studied. The determined values of Young's modulus, E, the Mooney-Rivlin elastic parameters C 1 and C 2, relaxation moduli, E(10 sec) and E(100 sec), as well as relaxation speed, Vr , and relaxation time T1, T2, and T3 were used to estimate the effect of the length of PmIA molecules segments on the mechanical behavior of block copolymers. It was found that block copolymers still displayed good elastic properties (especially using the molecular weight 2900 of PTMG which exhibited a more elastic behavior).