Synthesis and properties of alpha-omega-diaminoalkane based polyimides

Twenty semicryst. polyimides based on well-known arom. dianhydrides and aliph. a,w-diamines have been synthesized and characterized. Poly(BTDA-DAB) synthesized in a two-step process from 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and 1,4-diaminobutane (DAB) exhibits a rather exclusive balance between thermal/mech. properties and processability. In the series of a,w-diamines and BTDA, the glass transition temp. (Tg) increases linearly with the decrease in CH2 units, while the melting temp. (Tm) shows the well-known odd-even effect. For the as-synthesized poly(BTDA-DAB), Tg and Tm are 175 and 277 Deg, resp. After melt processing, a sharp decrease in crystallinity is obsd. with X-ray and DSC; however, annealing of injection-molded test bars results in a higher crystallinity. The semicryst. poly(BTDA-DAB) exhibits interesting mech. properties, e.g. a G' modulus of 1.7 kN.mm-2 and an Izod impact of 3.4 kJ.m-2. [on SciFinder (R)