MODIFICATION OF POLYURETHANE WITH WHOLLY-RIGID POLY(M-PHENYLENE ISOPHTHALAMIDE)

Flexible polyurethane (PU) was reinforced by wholly-rigid aromatic pol yamide poly (m-phenylene isophthalamide) (PmlA) (Nomex) by physical po lyblending and chemical copolymerization. Three polyurethane elastomer s were blended physically with various amounts of high molecular weigh t Nomex to form twelve PU/Nomex polyblends in order to modify their ph ysical properties. Also three multiblock copolyamides (PU-Nomex)were s ynthesised with a low molecular weight diamine-terminated Nomex prepol ymer as a hydrogen donor for chain extending. From differential scanni ng calorimetry and Rheovibron measurements it was shown that both the polyblends and multiblock copolyamides exhibited a glass transition te mperature under 0 degrees C and had a higher storage modulus, E', than those of the polyurethane. Scanning electron microscopy revealed that the polyblends and multiblock copolyamides had a dispersed phase stru cture. From the wide-angle X-ray diffraction pattern of the polyuretha ne and multiblock copolyamides it was found that the degree of stress- induced crystallization was dependent on the composition of the soft a nd hard segments and also the degree of its stretching. With regard to mechanical properties, it was found that both the tensile strength an d elongation of the multiblock copolyamides had a more significant rei nforcing effect than those of the polyblends and polyurethanes.