| 초록 |
Glass transition temperature of the crosslinked polyimide is very high and thermogravimetric analysis also shows excellent thermal stability. In this study, we examined crosslinking behavior of polyimide containing acetylene moiety. Polyimides containing pendent acetylene group, 3,5-diamino-4-phenylethynyl-benzophenone (DAPEBP) and 3,5-diaminoethynylbenzene (DAEB) were prepared with pyromellitic dianhydride (PMDA) and the equimolar diamines which controlled the ratio of acetylene moiety and 4,4’-oxydianiline (ODA) in dimethylacetamide (DMAc). In DSC thermogram of polyimde the exothermal onset temperature appeared between 300 and 370℃, and the amount of exotherm were 1.1 ~ 10.5 cal/g according to the amount of acetylene moiety. At the same acetylene content, after higher heat treatment, the amount of exotherm was smaller. Its exotherm was slightly observed as heat treated at 400℃. In viscoelastic analysis, modulus drop was observed around 350℃ and disappeared at treated 400℃. Glass transition temperature (Tg) was increased as crosslinking density was increased. As higher crosslinking density, tensile modulus was more increased and elongation was more decreased. Tensile strength was remained constantly. |
