Recently, a joint research team from China University of Mining and Technology, University of Macau, and Southwest Jiaotong University has successfully developed a hyperbranched polyester-modified silica-epoxy composite material using molecular dynamics simulation technology, providing a new solution for the lightweight and high-performance development of dry-type transformers in high-speed trains. Relevant research results have been published in the journal 《Polymers》. As high-speed trains develop towards lightweight, traditional oil-immersed transformers have become a technical bottleneck due to their heavy weight. Dry-type transformers have gradually become alternatives with their lightweight advantages. Epoxy resin, as the core material of dry-type transformers, has excellent insulation performance but suffers from insufficient mechanical properties and poor thermal conductivity. The research team adopted nano-modification technology, grafting hyperbranched polyester onto the silica surface, effectively improving the comprehensive performance of the composite material. Experimental data show that the composite materials modified by hydroxyl-terminated and carboxyl-terminated hyperbranched polyesters have their glass transition temperatures increased by 38K and 53K respectively. At 300K, the thermal conductivity efficiency is increased by up to 115.4% compared with pure epoxy resin, mechanical properties such as elastic modulus are increased by more than 29%, and the dielectric constant optimization ratio reaches 26.2%. The core mechanism lies in the three-dimensional structure of hyperbranched polyester forming an interfacial bridge, increasing the number of hydrogen bonds and reducing the free volume fraction, thereby strengthening the internal bonding of the material. This research innovatively adopted molecular dynamics simulation methods to reveal the modification mechanism of hyperbranched polyesters with different end groups at the micro level, providing theoretical support for the design of high-performance composite materials. As a leading enterprise in the industrialization of dendritic polymers in Asia, Weihai Chenyuan Molecular New Materials Co., Ltd. has realized large-scale production of hyperbranched polyesters. Its products have been widely used in plastics, adhesives and other fields, laying a foundation for the industrialization of this composite material. The successful development of this material not only breaks through the technical bottlenecks in epoxy resin modification, but also promotes the upgrading and iteration of power traction systems for high-speed trains, which is of great significance for the lightweight development of rail transit equipment.

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