Polyamic acid solution was prepared by the reaction of pyromellitic dianhydride and various aromatic diamines in a highly polar solvent, such as N-methyl-2- pyrrolidone or N,N -dimethylacetamide. And polyimide film was obtained by the thermal imidization of casted polyamic acid film in the electric furnace. Effect of thermal imidization conditions i.e, environment, temperature, time and thickness of film on the degree of imidization were investigated. With these studies, the degree of imidization in nitrogen flow or vacuum was found to be higher than that in air. The thinner film showed lower rate of imidization initially but the similar degree of imidization after the degree of imidization was leveled off. The higher temperature gave the higher degree of imidization but the stepwise heating imidization was considered to be better for smooth film formation. The degree of imidization was not affected by the extent of vacuum during thermal imidization. The thermal stability of obtained polyimide film was compared to that of commerical Kapton-H film.

Pyromellitic dianhydride와 몇가지 diamine을 N-methyl-2-pyrrolidone 또는 N,N-dimethylacetamide 용매에서 반응시켜 polyamic acid용액을 합성한 다음 필름으로 casting하여 이를 전기로에서 열이드화시켜 폴리이미드를 제조하였다. 이때 열이미드화의 조건 즉 환경, 온도, 시간, 그리고 필름의 두께 등이 이미드화도에 미치는 영향을 조사하였다. 그 결과 이미드화도는 공기중에서 보다 질소기류나 진공하에서 크게 나타났으며 필름의 두께가 얇을수록 이미드화 속도는 느리지만 평형에 도달한 후의 이미드화도는 비슷한 값을 나타내었다. 또 일정한 온도에서 일정시간이 지나면 더 이상 이미드화가 일어나지 않게 되며 온도가 증가할수록 이미드화가 더 많이 되었다. 그리고 단계적으로 온도를 증가시킴으로써 매끈한 필름을 만들 수 있었으며 진공도는 이미드화도에 큰 영향을 주지 않았다. 제조된 폴리이미드 필름은 상품화된 Kapton-H 필름과 비슷한 열안정성을 가진다는것을 확인하였다.

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