Study On Polymerization Of Binary Polyamide

In this paper, a new polyamide-imide precursor, polyamic acid(PAA) was synthesized by a acyl chloride method with trimellitic anhydride chloride(TMAc) and m-Phenylenediamine(m-PDA)as monomers, N-methyl-2-pyrrolidone(NMP) as the solvent, and triethylamine as a acid-catcher for polymerization. Then, PAI was obtained by a direct high-temperature imidization of PAA.In polymerization, we optimized the influence factors such as the percent content of acid-catcher, solid content, polymerization time, the molar ratio of monomers, polymerization temperature, and stirring speed and then further optimized the interaction of these influence factors by uniform experimental design method. The optimized synthetic process parameters for PAA with higher molecular weight are following:Polymerization temperature is 0~5℃; solid content is 27.84%; polymerization time is 161.5 min; the percent content of acid-catcher is 0.3149%; the molar ratio of monomers is 1:0.9691.In imidization process of PAA, a direct high-temperature imidization was adopted. The imidization degree was measured by 1H-NMR and FT-IR. The thermal properties were investigated by DSC and TGA. We also studied the change trend of PAI intrinsic viscosity with imidization time and temperature and the relationship between PAI intrinsic viscosity and its performances. The research results indicated: The viscosities of the as-synthesized PAI are 0.24-0.84 d L/g; the glass transition temperatures of the as-synthesized PAI are 305.2~330.5 ℃; 5% weight loss temperature(Td5%) of the as-synthesized PAI is higher than 450℃ in N2 atmosphere. Compared to the reference Torlon-PAI, the as-synthesized PAI has a higher glass transition temperature, so its thermal stability is improved.