聚酰亚胺/二氧化硅纳米尺度复合材料的研究

STUDY ON POLYIMIDE/SILICA NANOCOMPOSITE FILMS

通过正硅酸乙酯（ＴＥＯＳ）在聚酰胺酸（ＰＡＡ）的Ｎ，Ｎ’二甲基乙酰胺（ＤＭＡｃ），溶液中进行溶胶凝胶反应，制备出不同二氧化硅含量的聚酰亚胺／二氧化硅（ＰＩ／ＳｉＯ２）复合薄膜材料．二氧化硅含量低于１０ｗｔ％的样品是透明浅黄色薄膜；二氧化硅含量高于１０ｗｔ％的样品是不透明棕黄色薄膜．利用红外光谱、扫描电镜、热失重分析、动态力学分析、热膨胀系数测试和应力应变测试等方法研究了此类材料的结构与性能．结果表明，ＰＩ／ＳｉＯ２纳米复合材料具有较聚酰亚胺更高的热稳定性和更高的模量；线膨胀系数显著降低；拉伸强度和断裂伸长随二氧化硅含量而变化。

In order to improve the thermal stability and mechanical behavior of polyimide, a series of polyimide/silica composite films with different silica content up to 45 wt% were successfully prepared by sol gel reaction of tetraethoxysiliane in the presence of polyamic acid, a precursor of polyimide. The films with silica content less than 10 wt% were yellow and transparent, whereas the films with silica content higher than 10 wt% were yellow and opaque. The structure and physical properties were studied by FT IR, TGA, DMA, TEC, stress strain analysis and SEM. The results indicated that these polyimide/silica composite materials were nanocomposite materials. The density, decomposition temperature and modulus increased with increasing silica content,and the linear thermal expansion coefficient of the silica in the composite films decreased, whereas tensile strength and elongation at break have maxium with the change of silicate content.