The research progress of epoxy resin reinforced by different types of fillers, including carbon nanomaterials, ceramics, metals, and natural fillers in recent years was reviewed. The reinforcement effects of types, dispersion, and surface modification of fillers on the mechanical properties of epoxy resin were summarized in detail. And the research and development direction of reinforced modification of epoxy resin were also prospected.

In the study of damage mechanisms of composite materials, acoustic emission (AE), as a nondestructive testing technique, has gained excellent application results due to its high accuracy, real-time performance, insensitivity to geometry, and wide application prospects. In this paper, the analytical methods and application status of acoustic emission technology on damage mechanism of composite materials were summarized, the advantages and disadvantages of acoustic emission technology in the study of damage mechanism of composite materials were comprehensively elaborated, and the key technologies that need to be solved urgently were also explored, and the prospects of its application in the field of composite materials were envisioned.

Epoxy resin (EP) has been widely applied in electrical insulating materials, but with a low thermal conductivity, it cannot meet the requirement of heat dissipation in modern electrical equipment with high-power density. In this paper, silver acetate (AgAc) and 2-ethyl-4-methylimidazole (2E4MI) complex was deposited on boron nitride (BN) surface to prepare imidazole-silver modified BN hybrid materials (Ag(2E4MI)₂Ac@BN), then Ag(2E4MI)₂Ac@BN was filled in EP to prepare Ag(2E4MI)₂Ac@BN/EP composites,and its thermal conductivity was studied. The results show that when the volume fraction of filler is 20%, the thermal conductivity of Ag(2E4MI)₂Ac@BN/EP composites is 1.72 W/(m·K), which is 79.2% higher than that of BN/EP composites (0.96 W/(m·K)). The results of Monte Carlo simulation show that in the EP matrix, the thermal contact resistance (R_c) of Ag(2E4MI)₂Ac@BN is 2.7×10⁶ K/W, which is lower than the that of BN (R_c=5.5×10⁶ K/W). In comparison with BN/EP composites, Ag(2E4MI)₂Ac@BN/EP composites exhibit higher tensile strength and dielectric loss tangent (tanδ), lower dielectric strength and volume resistivity, while maintain good electrical insulating properties.

In order to develop a safe and eco-friendly accelerator, the differences between zinc neodecanoate and zinc naphthenate were studied from the three aspects of volatility characteristic, Zn²⁺ ion content, and the promoting curing characteristics of epoxy anhydride resin. Using high purity bisphenol A epoxy and methyl hexahydrophthalic anhydride as resin matrix, zinc neodecanoate and zinc naphthenate accelerators was added to the resin matrix,respectively. And then resin cured samples were prepared through the same process, and the glass transition temperature (T_g) and thermogravimetric curves of the samples were tested. The results show that due to the characteristic of single molecular structure, high Zn²⁺ content, and very low volatile organic compounds (VOCs), zinc neodecanoate is environmentally friendly. Comparing to zinc naphthenate, zinc neodecanoate requires a higher temperature to ensure complete curing of the epoxy anhydride resin. But under the same existing process conditions, the T_g of cured sample accelerated by zinc neodecanoate can reach 152℃, which is 11℃ higher than that of zinc naphthenate (141℃), indicating that the cured product accelerated by zinc neodecanoate has better thermomechanical properties.

The surface of basalt fibers was modified by nano alumina, and then modified basalt fiber/epoxy resin composite (BFRP) was prepared by lamination method, and the effect of nano-Al₂O₃ content on the insulation and mechanical properties of the modified composite was experimentally analyzed. The results show that when the mass fraction of nano-Al₂O₃ is 1.0%, the interface modification effect of BFRP is the best. Compared with untreated composites, the dielectric loss factor of 1.0K-BFRP reduces by 38.13%, the surface flashover voltage increases by 42.96%, and the breakdown voltage increases by 33.96%, demonstrating more superior insulation performance; the tensile strength, flexural strength, and interlaminar shear strength increases by 26.46%, 48.19%, and 66.06%, respectively, and the glass transition temperature increases by 4.49℃.

In order to obtain polypropylene based cable insulating materials with excellent dielectric properties, polypropylene based composites adding with nano MgO modified by silane coupling agent KH570 was prepared by melt blending method. The effect of nano MgO addition on the microstructure, dielectric properties, and mechanical properties of of the composites was studied. The results show that nano MgO promotes the transformation of polypropylene from α crystallographic orientation β, the interface of polypropylene and nano MgO is well bonded after the nano MgO is modified by KH570. The addition of nano MgO can inhibit charge injection, when the mass fraction of MgO is 1%, the composite has the smallest space charge density, which is 0.6 C/m², while excessive addition of MgO can lead to local charge accumulation in the composites. When the mass fraction of nano MgO is 1%, the composite shows the highest tensile strength (24.6 MPa), while the breaking elongation decreases with the addition of MgO. The direct current breakdown strength of pure polypropylene based material is the lowest. At 100℃, the direct current breakdown strength of polypropylene based composite materials with a MgO mass fraction of 1% is the highest (302 kV/mm), which is only 28.77% lower than that at 20℃.

A high phosphorus content epoxy resin (DPOEP) was synthesized by using 2,5-dihydroxybenzyl(diphenyl)phosphine oxide (DPOHQ) and epichlorohydrin (ECH) as reactants, and then the structure of DPOEP was characterized by Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The curing reaction characteristics of DPOEP with the curing agent of active ester resin DFE617 was studied, and the effects of DPOEP content and phosphorus-containing epoxy resin structure on the flame-retardant performance, dielectric properties, and thermal stability of dicyclopentadiene (DCPD) epoxy resin curing system were investigated. The results show that the curing process of DPOEP/DFE617 system follows a first-order reaction. DPOEP can promote the carbonization of condensed phase in the DCPD epoxy resin/DFE617 system, and the limiting oxygen index of cured resin reaches 36.6%-38%, achieving V-0 rating in the UL94 test. The dielectric loss factor of the epoxy resin curing system decreases with the increase of DPOEP content. At a lower content of DPOEP, the epoxy resin cured material is halogen-free and flame retardant while maintaining good thermal properties.

In order to solve the problem of blank cracking in the pressing process of special-shaped nozzle, we designed a near-clean forming special-shaped nozzle pressing mold independently, and optimized the structure of the mold gradually. At the same time, the process parameters such as pressing pressure, pressing speed, and holding time were optimized based on the existing pressing process. The results show that, through the gradual optimization of the structure of the special-shaped pressing mold, the cracking problems of the arc transition area and the bottom of the V-shaped pad of the nozzle were solved. Through the optimization of the pressing process, the density consistency of each position of the nozzle blank is improved, the mechanical and electrical properties of the arc transition area have little difference with those of the two ends, and the raw material loss of the nozzle pressed by this process is reduced by about 30%.

In order to investigate the ageing characteristics of the FRP/RPUF interface of composite insulation cross-arm under the effect of water intrusion, FRP/RPUF interface specimens were prepared, and water intrusion and destruction process in the FRP/RPUF interface was accelerated by hygrothermal ageing method. According to the test results of water absorption, shear strength, and leakage current, the ageing characteristics of the FRP/RPUF interface under water intrusion were obtained by combining with SEM, FTIR, and TGA. The results show that water intrusion can cause moisture plasticisation of the interface, reduce the shear strength and increase the leakage current, while that destructive effects decrease with the dissipation of water; hydrolytic reaction of FRP/RPUF interface material undergoes under the effect of water, leading to the generation of local defects and the increase of impurity ions, which further destroys the mechanical and electrical properties of the interface.

At present, there is a lack of effective liquid repair materials for ablation defects in the buffer layer of high-voltage cables, resulting in the inability to timely and effectively eliminate the hidden dangers of ablation defects in high-voltage cable lines. In this paper, acrylic based buffer layer ablation defect liquid repair materials were prepared and repair experiments were conducted on actual ablation defects in cable buffer layer. The repair effect of carbon black content in repair solution on the electrical properties of the buffer layer was studied. The results show that when the mass fraction of carbon black in the repair solution coating is 20%, the volume resistivity of the repaired buffer layer decreases to the level of new buffer layer and basiclly remains unchange with temperature. Based on the characterization of micro morphology, it is analyzed that the repair solution forms a carbon black coating on the fiber surface of the buffer layer, covering the original uneven coating and non-conductive particles. At the same time, the continuous water blocking powder layer formed by ablation on the inner side of the non-woven fabric is repacked by the carbon black coating, rebuilding the electrical connection of the buffer layer, thus effectively repairs the erosion defects of the buffer layer.