Studies on the Synthesis and Propeties of Polyimides; III. Effects of solvents on PMDA-Polyimides

Abstract

Pyromellitic dianhydride (PMDA)??? 4,4''-diaminodiphenylether (ODA) ?????? benzidine (BZI)??? N-methyl-2-pyrrolidone (NMP) ?????? N,N-dimethylacetamide (DMAc)??? ?????? ?????????????????? ?????? ???????????? ?????? polyamic acid (PAA)???????????? ????????? ?????????????????? ?????? ?????????????????? ???????????????????????? ???????????? ???????????? ????????? ??????, ????????? ??????, ???????????? ?????? ?????? ?????? ?????????????????? ????????? ???????????????. ??? ?????? DMAc????????? ???????????? ?????? ????????? NMP????????? ????????? ???????????? ?????????????????? ?????? ??????????????? ?????? ????????? ??????????????? ????????????????????? ?????? ????????? ???????????????. ??? diamine??? ????????? ??????????????? ?????? ????????? ?????????. ???????????? ???????????? NMP??? ???????????? ??????????????? ?????????????????? ?????????????????? ????????? ?????? ?????????????????? DMAc??? ?????? ?????? ???????????? ????????? ????????? ??? ??? ?????????. ???????????? ?????????, ????????? ??? ???????????? ???????????? ?????? ????????? ??????????????? ?????????????????? ?????? ???????????? ????????? ?????? ?????????????????? ?????????????????? ????????? ???????????? ?????????????????? ?????????????????? ???????????? ??? ?????????. ??? PAA ????????? 10%??? ????????? ?????? ??????????????????????????? ???????????? ????????? ?????? ????????? ????????? ????????? ?????? ?????? ???????????? PAA ????????? ???????????? ???????????? ??? ??? ?????????. Polyamic acid(PAA) solution was prepared by the condensation polymerization of pyromellitic dianhydride (PMDA) and 4,4''-diaminodiphenylether (ODA) or benzidine (BZI) in a highly polar solvent such as N-methy1-2-pyrrolidone (NMP) or N,N-dimethyl acetamide (DMAc). The polyimide (PI) film was then obtained by the thermal imidization oa casted PAA film. For thermal imidization of PAA film obtained from PMDA and ODA, the effects of solvent i.e, the contents of solvent, the sorts of solvent and of cosolvents on the degree of imidization were investigated. It was found that the degree of imidization of which PAA film polymerized in DMAC was higher than that in NMP for the both conditions of under atmosphere and nitrogen flow. For the PAA film obtained from PMDA and BZI, the similar result was obtained. The degree of imidization was not much affected by the contents of NMP or DMAc in PAA film, however it was slightly changed by the addition of cosolvent such as methanol, ethanol or toluene. The addition of cosolvent such as ethanol or tetrahydrofuran was found to be used as a stabilizer of PAA solution from the observation of viscosity change with storage time.clos