聚酰胺酸盐法制备纳米SiO2/PI复合薄膜

1)哈尔滨理工大学材料科学与工程学院,哈尔滨 150040; 2)哈尔滨理工大学工程电介质及其应用教育部重点实验室,哈尔滨 150080

复合薄膜; 聚酰氨酸盐; 氧化硅; 聚酰亚胺; 纳米分散; 热分解; 电击穿场强; 绝缘性

Nano-SiO2/PI composite films prepared via poly(amic acid)salts process
Yan Liwen1, Weng Ling1, Li Hongxia1, Xia Qianshan1, Cui Weiwei1, and Liu Lizhu1, 2

Yan Liwen1, Weng Ling1, Li Hongxia1, Xia Qianshan1, Cui Weiwei1, and Liu Lizhu1, 21)School of Materials Science and Engineering, Harbin University of Science and Technology, Harbin 150040, P.R.China2)Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, Harbin University of Science and Technology, Harbin 150080, P.R.China

composite film; poly(amic acid)salts; silica; polyimide; nanoscale dispersion; thermal decomposition; breakdown field strength; insulativity

DOI: 10.3724/SP.J.1249.2014.01077

备注

以均苯四甲酸二酐和4, 4'-二胺基二苯醚为聚合单体,制备聚酰胺酸,利用有机碱三乙胺与聚酰胺酸中—COOH的中和反应,制备具有水溶性的聚酰亚胺前驱体——聚酰胺酸盐; 将正硅酸乙酯的水溶液加入聚酰胺中,利用正硅酸乙酯的水解使得水解产物SiO2以纳米尺寸均匀分散在聚酰胺中,经热亚胺化处理制备出SiO2质量分数不同的SiO2/PI复合薄膜.采用扫描电子显微镜对复合薄膜的断面微观结构进行分析,实验结果表明,SiO2在PI基体内分散均匀.当SiO2质量分数为20%时,仍未出现团聚现象.复合薄膜的力学性能、热性能及电性能测试结果显示,由于SiO2的生成,复合薄膜的力学性能稍有下降; 薄膜的热分解温度随着SiO2质量分数的增大逐渐升高; 复合薄膜的电击穿场强由纯PI薄膜的160.0 kV/mm提高到229.8 kV/mm(SiO2质量分数16%),随着SiO2质量分数的增大,复合薄膜的体积电阻率和表面电阻率均呈先增后减趋势; 引入SiO2显著提高了复合薄膜的绝缘性,拓展了其在电气绝缘领域的应用.

A water-soluble polyimide precursor called polyamide acid salt(PAAs)was synthesized via the neutralization reaction of triethylamine(TEA)and polyamide acid(PAA). PAA was generated from the monomer pyromellitic dianhydride(PMDA)and 4,4'-oxydianline(ODA)beforehand. A series of silica/polyimide(SiO2/PI)composite films with different silica mass fraction were prepared from tetraethyl orthosilicate(TEOS)and PAAs. The uniform dispersion of SiO2 in PI matrix benefited from the direct hydrolysis of TEOS in PAAs. The microscopic morphology of composite films was characterized by scanning electron microscope(SEM). The dispersion of SiO2 in PI matrix was homogeneous even though the SiO2 mass fraction reaches 20%, which shows the excellent compatibility between SiO2 and PI in the composite films prepared by Poly(amic acid)salts. The mechanical, thermal performance and electrical properties of the SiO2/PI composite films were studied. The results show that both the tensile strength and the elongation at break decrease slightly with increasing SiO2 mass fraction. The thermal decomposition temperature of the composite films increases gradually with the increase of the mass fraction of SiO2. The breakdown field strength of the SiO2/PI composite film, 16% mass fraction of SiO2 addition, is 229.8 kV/mm while the pure PI film is 160.0 kV/mm. The volume resistivity of the composite films, as well as the surface resistivity, increases firstly and then decreases synchronously with the increase of the mass fraction of SiO2. The insulativity of the composite films is significantly improved by the introduction of SiO2, which facilitates the application of the PI composite films in the field of electrical insulation.

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