Synthesis and characterization of polyamic acid and polyimide

The co-polycondensation type polyamic acid (PAA) was synthesized using 4,4′- diaminodiphenylmethane (MDA) as diamine monomer,3,3′,4,4′-benzoph-enonetetracarboxylic dianhydride (BDTA) and pyromellitic acid dianhydride (PMDA) as dianhydride monomers under conventional heating solution polycondensation.Then PAA came into being polyimide (PI) by an imidization at low-temperature.It was characterized by inherent viscosity ([η]),fourier transform infrared (FT-IR),thermogravimetric curve (TG) analyses and X-ray diffraction (XRD).The FT-IR results were shown that,there were PI's characteristic peaks around 1 777 cm~1 and 1 723 cm~(-1). Thermogravimetric curve indicated that,PI's 10% thermal decomposition temperature under N_2 was 568℃.XRD spectrum demonstrates that obtained polyimide has low-order aggregation structure with a d-spacing of 0.506 9 nm.