原位法PI/TiO_2复合材料的制备及性能研究

Study on preparation and properties of in-situ PI/TiO_2 composites

以均苯四甲酸二酐(PMDA)、4,4’二氨基二苯醚(ODA)为原料,采用二步法合成了聚酰亚胺,即先制备聚酰胺酸前躯体,再由聚酰胺酸亚胺化制得聚酰亚胺,并对聚酰亚胺的制备工艺进行了研究。再以钛酸正丁酯为原料,采用水解法制备了TiO_2。然后采用共混法和原位法两种方法制备出聚酰亚胺/TiO_2复合膜。对制备出的TiO_2进行了红外光谱,扫描电镜和粒度分析等测试。红外光谱表明该TiO_2在500~800 cm^(-1)处有特征峰。扫描电镜对该TiO_2的表面形貌进行了观察。粒度分析表明该TiO_2的平均粒径为0.9μm。对制备出的聚酰亚胺以及聚酰亚胺/TiO_2复合膜进行了红外光谱、扫描电镜、电击穿、体积电阻率和表面电阻率和力学性能等一系列的测试。红外光谱分析表明聚酰亚胺亚胺化完全;扫描电镜分析表明,制备的杂化薄膜中,TiO_2粒子均匀地分散在PI基体中,粒子尺寸在100~200 nm之间,有一小部分无机粒子出现团聚现象;电击穿测试表明,随着TiO_2含量的增加,PI膜的抗电击穿性能变好;由PC40B型数字绝缘电阻测试仪测试分析表明,TiO_2掺杂后体积电阻率和表面电阻率均增大,材料的绝缘性能变好;力学拉伸测试结果说明TiO_2掺杂后材料的最大应力和断裂伸长率都变大,抗拉伸性能变好。

In this paper, polyimide was synthesized by two-step with the raw materials of pyromellitic dianhydride （PMDA） and 4,4＇-diamino diphenyl （ODA）. Firstly, the polyamic acid precursor was synthesized, then polyimide was obtained by the imidization of polyamic acid, and the preparation of technology of polyimide were studied. TiO2 was prepared by the hydrolysis with the raw materials of n-butyl titanate. Finally, PAA/TiO2 composites were prepared by situ method and directly blend method. The infrared spectroscopy, scanning electron microscopy and particle size analysis were used to test the TiO2 particles. Infrared spectrum showed that it had TiO2 characteristic peaks in range of 500~800 cm-~. SEM observed the surface morphology of the TiO2. Particle size analysis showed that the average particle size of TiO2 was 0.9 tim. IR spectroscopy, scanning electron microscopy, electrical breakdown were used to test the polyimide and polyimide/ TiO2 composite films, which were prepared formerly. Volume resistivity, surface resistivity and mechanical properties were also tested. It showed that the imidization of the composite film had been completed from IR testing results. It was found TiO2 particles were evenly distributed in the polyimide matrix by scanning electron microscopy testing, the range of particle size was 100-200 nm, a small part of the inorganic particles appeared the agglomeration; It showed that the electrical breakdown properties of the PI film became better, with the increase of TiO2 content from electrical breakdown testing results. The test results of PC40B digital insulation resistance tester showed that volume resistivity and surface resistance rate increased after the TiO2 was adulterated, the insulation became better. The results of mechanical tensile test showed that, when the TiO2 was adulterated, the maximum stress and elongation at break of PI became larger and tensile properties became better.