Synthesis and characterization of thermally stable semicrystalline polyimide based on 3,4′-oxydianiline and 3,3′,4,4′-biphenyltetracarboxylic dianhydride

The synthesis and characterization of a thermally stable semicrystalline polyimide based on 3,4'-oxydianiline (3,4'-ODA) and 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), end capped with phthalic anhydride, were carried out. The glass transition temperature and the melting temperature of this polyimide (abbreviated as 3,4'-ODA polyimide) were detected at 251 and 402 degreesC, respectively, by differential scanning colorimeter (DSC) measurement. The degree of crystallinity and heat of fusion for the annealed film of this polyimide, estimated by X-ray diffraction (XRD) and DSC measurements, were 28% and 32 J/g, respectively. The crystallization times of this polyimide under isothermal DSC measurement conditions were second order at below 300 degreesC. This result showed the 3,4'-ODA polyimide to be a polymer having first crystallization kinetics. The thermal stability of the 3,4'-ODA polyimide was compared with that of a known semicrystalline polyimide based on 1,3-bis(4-aminophenoxy)benzene and BPDA (abbreviated as TPER polyimide). The 3,4'-ODA polyimide displayed excellent thermal stability, as evidenced by thermogravimetric analysis especially in air atmosphere and melt viscosity study during storage time. (C) 2000 Elsevier Science Ltd. All rights reserved.