Preparation And Properties Investigations Of Polyimide Hybrid Films And Reactive Endcapped Imide Oligomers

With the rapid development of electrical, electronic, aerospace, microelectronics industry, the needs of high temperature resistance polymer materials are becoming increasingly urgent. The polyimide materials have excellect high and low temperature resistance properties, electrical properties, mechanical properties, radiation resistance and thermal stability. Many research papers have been pulished in recent years about organic-inorganic hybrid membrane, especially in PI/inorganic hybrid film. Most of them prepared hybrid film via sol-gel, rather than in-situ polymerization.According to above researches, a series of PI/TiO2 hybrid films based on 4,4'-oxydianiline (ODA) and 3,4,3',4'-biphenyltetracarboxylic dianhydride(BPDA) were prepared via in-situ polymerization by incorporation with varied content of nano-sized TiO2, which was surface modified by silane coupling agent (mecaptopropyltriethoxylsilane). The thermal stability, the coefficient of thermal expansion (CTE) and mechanical properties of the PI/TiO2 hybrid films was investigated. The microstructure was characterized by SEM, WAXD. The contact angle, dielectric property and ferroelectric property of hybrid films were also investigated. Research results showed that the introduction of nano-TiO2 lead to the reduced thermal decomposition temperature. But the average T5% of hybrid films are still higher than 520℃, meanwhile, dimensional stability of hybrid films exhibits an increase, as represented by decreased CTE. The surface modified nano-TiO2 particles were homogenously dispersed in the polyimide hybrid film with TiO2 content between lwt.% and 5wt.%. The PI/TiO2 hybrid films possess the higher dielectric constant (approximately 3.50) than the pure PI film (2.91). It was also showed that the Pmax and contact angle of hybrid films increase with increasing TiO2 doping content until 15 wt.% and 10 wt.%, respectively, to reach the maximum, and then decrease with further increasing TiO2 content.Compared to other materials,the polyimide materials have excellect high and low temperature resistance properties, electrical properties, mechanical properties, radiation resistance and thermal stability, But the processability of PI is not so good. The reactive endcapped imide oligomer not only have excellent temperature resisitance,but also is proved effective to increase processability of PI.This research employs the abundant forestry resources in Jiang Xi province, and introduces the alicyeic structure of camplor, rosin to the imide oligomer as end-capping agent. Thereby, a series of reactive alicyclic endcapped imide oligomers were prepared, Which slowed certain thermal and improved processing characteristic, Meanwhile, The application of corresponding natural forestry chemicals could be expanded and their added-value be realized by way of such structural transformation and utilization.