Synthesis and Characterization of Low Tg Thermally Stable Polyimide
Polyimide adhesives requre relatively low Tg and high thermal stability. For these purposes, we used three-steps procedure to synthesize dianhydride BPEA which has four benzene ring and three ether-linkage. While diamine m-BABB which has amino group and two carbonyl group located in meta-position were synthesized by two-steps procedure. More ether-linkage was used to lower Tg and increase flexibility of polymer chain, while carbonyl group was used to increase thermal stability and charge-transfer ability. We hope that these functional group can increase adhesion adility of polyimides. These two monomer were characterized carefully. Thermal properties, surface energy, and mechanical properties of polyimides were measured. We used BPEA to react with different diamines to synethesize a series of polyimides, inherent viscosity of polyamic acid were ranging from 0.54 to 0.6, which can be easily casting and thermally curing as thin film. Their Tg indeed became lower with more ether-linkage. Meta-position diamine had much lower Tg than para-position one. Critical surface energy basically changed with their Tg. The5%-weight-loss were ranging from to 550℃. We used diamine m-BABB and m-BAPS to copolymerize with dianhydride BTDA Their Tg, critical surace energies were lower with more percentage of m-BABB, While 5%-weight-loss and mechanical properties remain the same level. It seems not to be influences by the presence of m-BABB.
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