聚酰亚胺-二氧化钛纳米复合薄膜的热稳定性

Thermal Stability of PI-TiO_2 Nanocomposite Film

目的探究纳米颗粒对聚酰亚胺薄膜热稳定性的影响规律及影响机理。方法采用原位聚合法制备TiO_2含量不同的PI-TiO_2纳米复合薄膜,通过差热热重法分析复合薄膜的热稳定性,观察复合薄膜加热后的微观形貌,探讨复合薄膜的耐热机理。结果纳米颗粒的加入提高了薄膜的热稳定性,PI-5% TiO_2复合薄膜失重10%和50%时的温度分别较纯PI膜提高了19.3℃和20.7℃。复合薄膜的DTA曲线峰顶温度均高于纯PI膜,PI-5% TiO_2复合薄膜峰顶温度为637.8℃,较纯PI膜提升了40.1℃。随着TiO_2含量的增加,复合薄膜DTA曲线反应峰峰型逐渐变窄、增高且变得尖锐,复合薄膜的导热性能有所提高。结论纳米颗粒阻碍了聚酰亚胺分子的热运动,减缓了薄膜在分解过程中产生的空洞区域的扩散。聚酰亚胺基体中的纳米颗粒在薄膜中形成骨架结构,提高了薄膜的导热性和刚性。聚酰亚胺与纳米颗粒形成有机-无机相界面,界面层的聚酰亚胺分子具有更好的热稳定性,使得薄膜的反应热焓值增加。

Objective To explore the influence of nanoparticles on thermal stability of polyimide film and the influence mechanism. Methods In-situ polymerization was adopted to prepare the PI/TiO2 nanocomposite film, and the thermal stability and microstructure of composite film were tested through DTA-TGA and SEM. The composite film microstructure was observed after heatingto explore the mechanism of heat-resistant composite film by differential thermal analysis. Results The results showed that the nano- particles increased the thermal stability of film. The temperature of 5% composite film increased by 19.3 ℃ and 20. 7℃ under weightlessness of 10% and 50% respectively, compared to the pure film. The peak temperature of film with 5% component was 637.8 ℃, increased by 40.1 ℃ compared to the pure film. Through comparing the pattern of reaction peak, it can be found that the reaction peak of pure film was wide and smooth, while that of three kinds of composite films became narrow with the increase of components with higher and sharp pattern, indicating that the PI composition was fiercer and concentrated in the composite film. Conclusion The study indicated that the nano-particles hindered the thermal motion of PI and slowed down the void spread of film in the process of decomposition. The nano-particles formed the skeleton structure in the matrix, improving the thermal conductivity and rigidity of film. PI molecules at the interface of organic-inorganic phase interface had better thermal stability.