等离子体改性玻璃纤维增强的环氧树脂电气性能研究

发布时间：2018-07-28 21:40

【摘要】：玻璃纤维增强环氧树脂复合材料作为一种良好的绝缘材料,被广泛用于绝缘套管等电力设备中。由于玻璃纤维表面的活性问题导致其不能与环氧树脂基体之间形成良好的结合,容易使绝缘材料在生产和应用的过程中产生缺陷进而加速电力设备绝缘老化。等离子体表面改性是目前发展较快的新技术,它可以在短时间内高效率地处理材料,使玻璃纤维更易于和环氧树脂等有机胶黏剂结合。本文采用低温等离子体对玻璃纤维表面进行改性,研究了改性后的玻璃纤维对玻璃纤维/环氧树脂复合材料的电气和力学性能的影响。首先,采用介质阻挡放电在空气中大气压下产生的低温等离子体对无碱玻璃纤维进行改性实验,分别处理0s、180s、360s、540s,考察经不同时间改性后玻璃纤维表面形貌及化学组成成分的变化,并分析玻璃纤维的改性效果与等离子体处理时间之间的关系。实验结果表明,在空气中经不同时间等离子体处理后玻璃纤维表面出现不同程度的刻蚀痕迹,并且成功引入了 O-C=O等新的含氧极性官能团,这二者相互作用可以很好地提升玻璃纤维与环氧树脂的界面结合强度。但等离子体的处理效果并不是随时间的增加而增强的,基于本文的实验结果,在空气中大气压下对玻璃纤维进行等离子体处理的最佳方案为:电源频率11kHz,工作电压20kV,放电功率70W,处理时间180s。其次,采用不同含量等离子体改性后的玻璃纤维掺杂环氧树脂,制备成玻璃纤维/环氧树脂复合材料,并测试复合材料的局部放电起始电压、交流短时击穿电压、拉伸、弯曲强度,结合复合材料的断面形貌对比分析等离子体改性效果对复合材料的电气及力学性能的影响。实验发现采用经低温等离子体改性后的玻璃纤维制备的环氧树脂复合材料,电气和力学性能均有所提升。从复合材料的断面形貌来看,等离子体改性使玻璃纤维在环氧树脂中分散的更加均匀,并且玻璃纤维因拔出而留下的孔洞较少,与环氧树脂结合的更加紧密。改性后的玻璃纤维含量为20wt%时,复合材料的局部放电起始电压及交流短时击穿电压达到最高为23.2kV和33.5kV,提高了 6.9%和3.4%,拉伸、弯曲强度在改性后玻璃纤维为25wt%时达到最高,分别为61.325MPa和170MPa,提高了 29.1%和22.4%。综上所述,低温等离子体的化学刻蚀作用引起的玻璃纤维表面形貌的变化,以及表层极性基团的引入,是玻璃纤维表面活化处理中的主导过程,是提升复合材料的电气和力学性能的关键。当改性后玻璃纤维的含量达到20wt%～25wt%时,玻璃纤维/环氧树脂复合材料的电气和力学性能均达到最优。
[Abstract]:As a good insulating material, glass fiber reinforced epoxy composites are widely used in electrical equipment such as insulating sleeving. Due to the problem of glass fiber surface activity, it can not form a good combination with epoxy resin matrix, which can easily lead to defects in the process of production and application of insulating materials, and accelerate the insulation aging of power equipment. Plasma surface modification is a new technology, which can be used to treat materials efficiently in a short time and make glass fiber easier to bind to organic adhesive such as epoxy resin. The surface of glass fiber was modified by low temperature plasma. The effect of modified glass fiber on the electrical and mechanical properties of glass fiber / epoxy resin composite was studied. Firstly, the alkali free glass fiber was modified by low temperature plasma produced by dielectric barrier discharge (DBD) at atmospheric pressure. The surface morphology and chemical composition of glass fiber after different time modification were investigated. The relationship between the effect of glass fiber modification and plasma treatment time was analyzed. The experimental results show that the surface of glass fiber is etched in different degree after different time plasma treatment in air, and new oxygen-containing polar functional groups, such as O-C=O, have been successfully introduced. The interfacial bonding strength of glass fiber and epoxy resin can be improved by the interaction of the two. However, the effect of plasma treatment is not enhanced with the increase of time, based on the experimental results in this paper. The optimal scheme for plasma treatment of glass fiber at atmospheric pressure is as follows: power frequency 11kHz, working voltage 20kV, discharge power 70W, treatment time 180s. Secondly, glass fiber / epoxy resin composites were prepared by using different contents of plasma-modified glass fiber doped epoxy resin. The initial voltage of partial discharge, AC short-time breakdown voltage and tensile strength of the composites were measured. The effect of plasma modification on the electrical and mechanical properties of composites was analyzed by means of bending strength and cross-section morphology. It was found that the electrical and mechanical properties of epoxy resin composites modified by low temperature plasma were improved. According to the cross-section morphology of the composite, plasma modification makes the glass fiber disperse more evenly in epoxy resin, and the glass fiber has fewer holes left by pull-out, and the bond between glass fiber and epoxy resin is more compact. When the content of the modified glass fiber is 20 wt%, the initial voltage of partial discharge and the short time breakdown voltage of the composite reach the maximum of 23.2kV and 33.5 kV, which increase by 6.9% and 3.4%. The tensile and flexural strength of the modified glass fiber reaches the highest when the modified glass fiber is 25 wt%. 61.325MPa and 170 MPA were increased by 29. 1% and 22. 4%, respectively. To sum up, the changes of glass fiber surface morphology caused by chemical etching of low temperature plasma and the introduction of polar groups in the surface layer are the leading processes in the surface activation treatment of glass fiber. It is the key to improve the electrical and mechanical properties of composites. When the content of the modified glass fiber reaches 20wt% and 25wt%, the electrical and mechanical properties of the glass fiber / epoxy resin composite are optimized.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM215.1

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