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 po lyimide based on 3,4'-oxydianiline (3,4'-ODA) and 3,3',4,4'-biphenyltetraca rboxylic dianhydride (BPDA), end capped with phthalic anhydride, were carri ed out. The glass transition temperature and the melting temperature of thi s polyimide (abbreviated as 3,4'-ODA polyimide) were detected at 251 and 40 2 degreesC, respectively, by differential scanning colorimeter (DSC) measur ement. The degree of crystallinity and heat of fusion for the annealed film of this polyimide, estimated by X-ray diffraction (XRD) and DSC measuremen ts, were 28% and 32 J/g, respectively. The crystallization times of this po lyimide under isothermal DSC measurement conditions were second order at be low 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'-O DA polyimide was compared with that of a known semicrystalline polyimide ba sed on 1,3-bis(4-aminophenoxy)benzene and BPDA (abbreviated as TPER polyimi de). The 3,4'-ODA polyimide displayed excellent thermal stability, as evide nced by thermogravimetric analysis especially in air atmosphere and melt vi scosity study during storage time. (C) 2000 Elsevier Science Ltd. All right s reserved.