CRYSTALLINE HOMOPOLYIMIDES AND COPOLYIMIDES DERIVED FROM 3,3',4,4'-BIPHENYLTETRACARBOXYLIC DIANHYDRIDE 1,3-BIS(4-AMINOPHENOXY)BENZENE 1,12-DODECANEDIAMINE .1. MATERIALS, PREPARATION, AND CHARACTERIZATION

Crystalline homopolyimides are shown to occur by DSC from 3,3',4,4'-bi phenyltetracarboxylic dianhydride (BPDA) and either 1,3-bis(4-aminophe noxy)benzene (134APB) or 1,12-dodecanediamine (C12). Additionally, cop olyimides synthesized from these monomers are crystalline in all compo sitions studied. Each composition was found to have a singular glass t ransition temperature, which is rectilinearly dependent on the percent of 134APB/C12. A similar relationship is found for the crystallizatio n temperature but not for the apparent melting temperature. Upon heati ng, a triple-melting behavior was observed when materials were crystal lized at large degrees of supercooling. Otherwise, a conventional doub le-melting behavior was seen. The equilibrium melting temperature (T-m degrees) was estimated using the Hoffman-Weeks method. Results indica te that compositions with 134APB composition greater than or equal to 40% are dominated by the 134APB/BPDA polyimide phase, and below it by the C12/BPDA polyimide phase. The value of T-m degrees for the 134APB/ BPDA polyimide is about 410 degrees C and for the C12/BPDA polyimide i s about 243 degrees C.