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°C, 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°C. 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.