Preparation and Properties of Recyclable Vitrified Epoxy Resin Based on Transesterification
Liu Hechen1,2, Sun Zhanglin1, Liu Yunpeng1,2, Ge Qi1, Wu Xuan1
1. Hebei Key Laboratory of Green and Efficient New Electrical Materials and Equipment North China Electric Power University Baoding 071003 China; 2. State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing 102206 China
Abstract：In recent years, epoxy resin composites have been widely applied in insulation equipment and module packaging, due to their exceptional performance including good heat resistance properties, excellent mechanical properties, and great insulating properties. At present, incineration and landfills are often used, wasting resources and causing serious pollution to the environment. With the world's energy shortage and environmental degradation, the development of new recyclable resin-based composites has gradually become the focus of research on environmentally friendly electrical equipment. In order to develop recyclable resin materials for the power industry, the synthesis and properties of ester-exchange-based glassy epoxy resins are investigated in this paper to explore the possibility of applying glassy epoxy resins in the power equipment manufacturing industry and their recycling properties. Firstly, the selection experiments were carried out to investigate the potential application and recovery performance of the glassy epoxy resins in the power equipment manufacturing industry, including zinc acetylacetonate, zinc acetate, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and stannous isooctanoate. The experiments showed that the catalytic effect of zinc acetylacetonate was better than that of zinc acetylacetonate at the same molar addition level, while zinc acetate was less compatible with the resin and some zinc acetate crystals remained in the resin after curing; TBD was similar to zinc acetylacetonate but the preparation process of TBD was more complicated and costly, while stannous isooctanoate was less effective and the resin was not completely cured. Therefore, zinc acetylacetonate was used as the transesterification catalyst for this experiment. The effects of the catalyst and curing agent ratios on the structural, thermal, mechanical and electrical properties of the resin were systematically investigated, with emphasis on its applicability in the power industry. The resin system exhibits good mechanical and electrical properties. After the introduction of zinc acetylacetonate, the electrical insulation properties were slightly reduced compared to the conventional epoxy resin due to the effect of zinc ions, but all electrical performance indicators met the relevant standards in the power industry. Finally, the degradation and recovery properties were explored using physical hot-pressure recovery and thermal dissolution of alcohol solvents. The recovered Vitrimer resin was crushed and recovered by physical hot pressing at 180℃ and 10 MPa, and the mechanical strength of the recovered resin was about 76% and the electrical insulation strength was 90%.The chemical degradation recovery rate increased with the increase of zinc acetylacetonate catalyst in the resin system, and the dissolved alcohol solvent and resin mixed solution could be separated by reduced pressure distillation. The recovered resin oligomers can be recycled as part of a new resin replacement in a new curing system, and the separated alcohol solvent can be reused as a degradation solution to achieve closed-loop recycling and thus avoid wastage of reagents. The Vitrimer resin system has excellent electrical insulation properties and can be recycled at the same time, offering the possibility of recycling resin-based electrical equipment and recycling high-value materials such as internal copper windings and carbon fibres, and is expected to provide a new direction of choice for environmentally friendly electrical equipment materials.
刘贺晨, 孙章林, 刘云鹏, 葛琦, 吴璇. 基于酯交换的可回收类玻璃化环氧树脂制备与性能研究[J]. 电工技术学报, 2023, 38(15): 4019-4029.
Liu Hechen, Sun Zhanglin, Liu Yunpeng, Ge Qi, Wu Xuan. Preparation and Properties of Recyclable Vitrified Epoxy Resin Based on Transesterification. Transactions of China Electrotechnical Society, 2023, 38(15): 4019-4029.
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