聚西胺酸低溫亞西胺化之研究

Abstract

本論文主要利用PMDA/ODA系統的聚西胺酸進行低溫亞西胺化之研究. 以 p-hydroxybenzoic acid(p-HBA)為PAA亞西胺化的催化劑時,其亞西胺化的 速率在攝氏110,120時亞西胺化的速率與p-HBA濃度平方呈線性關係,但攝 氏130,140時則亞西胺化速率與p-HBA濃度三次方有直線的關係 對於加入 p-HBA的PAA黏度,在攝氏25度度會隨著p-HBA濃度增加,在攝氏100時,會隨 著p-HBA濃度增加而下降.關於加入p-HBA的聚亞西胺的機械特性會變得柔 軟,楊氏模數隨著p-HBA濃度增加而下降.關於熱裂解溫度亦有相同的趨勢. 加入p-HBA的聚亞西胺表面會隨著其濃度的增加而變為粗糙. 在使用親水 試劑2,2-dimethoxypropane,ethyl orthoformate,ethyl orthoacetate 的初步動力學研究中,這三種親水試劑皆能促進亞西胺化,其適合的反應溫 度在攝氏70~90度間,若使用高於攝氏100度時,PAA黏度會下降,聚西胺酸的 成膜性差,機械特性差. A series of polyimides were prepared from polyamic acid(PAA), which is Synthesized by pyromellitic dianhydride and 4,4'-oxydianiline monomer,with a catalyst of p-hydroxybenzoic acid (p-HBA) and a variety of hydrophilic reagents, such as 2,2-dimethoxypropane,ethyl orthoformate and ethyl orthoacetate. The properties of the obtained polyimides and the kinetics of imidization reaction from PAA will be studied. The initial rate of imidizatio醯酸低溫亞西胺化之研究. concentration of p-HBA as the imidization at 110C or 120C,whereas the initial rate of imidization is proportional to cubic of the concentration of p- HBA at 130C or 140C It can be seen that the viscosity of PAA increases with increasing the concentration of p-HBA at 25C,but it decreases with increasing the coneentration of p-HBA at 100C from rheology test.Generally speaking,the modulus of the obtained polyimide, using p-HBA as a catalyst,decreaseswith increasing p-HBA/PAA molar ratio until the molar ratio is 0.75. Similarly, the tendency of relationship between the thermal degradation temperature andthe p-HBA/PAA molar ratio is the same as that of the modulus with the molar ratio .However the difference of the thermal stability is insignificant for these polyimides. The surface of the polyimides are also analyzed by atomic force microscopytechnique.It can be observed that the mean roughness of the surface of polyimide films increases with increasing the concentration of p-HBA. It also found that the viscosity of PAA solution, whivh contains a certain of hydrophilic reagent, is decreased as the temperature of imidization is higher than 100C. Therefore, it is not possible to obtain even polyimide films if the temperature is above 100C. However,a good film of polyimide can be obtained as the temperature of imidization is controlled at range of 70~90C.