Preparation And Properties Of High Thermal Conductivity Functionalized Zeolite/XLPE Composites

Cross-linked polyethylene(XLPE)materials have excellent electrical insulation properties and physical and mechanical properties,and play an important role in high voltage DC transmission project in our country.With the rapid development of power transmission,the requirements for the dielectric and thermal conductivity of insulating materials are increasing day by day now.At present,the modification of composite materials by nano-doping can effectively improve the performance of dielectric materials,which is a research hotspot in the field of engineering dielectrics in my country.It is found through experiments that the zeolite particles composed of porous structure can better enhance the insulation performance and thermal conductivity of the polymer composite material after being added to the composite material.However,due to its high surface energy characteristics,zeolite particles are prone to agglomeration of large particle sizes in the XLPE matrix,resulting in uneven doping of the composite material and poor overall performance.The low thermal conductivity of XLPE limits the transmission voltage level and transmission distance of high-voltage DC cables using it as the main insulating material.This thesis is based on cross-linked polyethylene(XLPE)material,in order to solve the problem of its low thermal conductivity and poor dispersion in the doping process,based on ZSM-5 zeolite particles,the modified zeolite particles(TAICS-ZSM-5-HBP)were prepared by grafting hyperbranched polyaramid and silane-treated crosslinking agent(TAIC)onto its surface in two experiments.Then,the modified particles were inserted into the XLPE network structure through a thermal crosslinking reaction to prepare a modified composite material(XLPE/TAICS-ZSM-5-HBP).The intermediate product(TAICS),its successful preparation was proved by H NMR spectrum test;The modified particles grafted with hyperbranched polyaramid(ZSM-5-HBP)and TAICS-ZSM-5-HBP modified particles were tested by infrared spectroscopy,which confirmed the successful progress of the grafting reaction.This confirmed the successful preparation of TAICS-ZSM-5-HBP modified particles.Then,based on the principle of chemical cross-linking reaction,XLPE/TAICS-ZSM-5-HBP composites were prepared by melt mixing and heating tableting.The results of the gel content test found that the gel content of the XLPE/TAICS-ZSM-5-HBP composite was higher than that of the XLPE and XLPE/ZSM-5 composites,It shows that TAICS-ZSM-5-HBP particles are successfully introduced into the cross-linked three-dimensional network structure of XLPE;Scanning electron microscopy(SEM)found that TAICS-ZSM-5-HBP particles had good d ispersion in XLPE,which verified that the surface grafting modification of zeolite particles could reduce their surface energy and improve the dispersion.The thermal conductivity and dielectric properties of nanocomposites were studied by comparative experiments.The comparison results show that the dielectric properties of XLPE/TAICS-ZSM-5-HBP composites are high,The introduction of TAICS-ZSM-5-HBP particles can better inhibit the growth of XLPE electric dendrites and the injection and migration of spac e charges,which is mainly due to the good dispersion of particles in the composite material to increase the interaction interface between particles and XLPE,At the same time,the trap depth and energy level of the composite material are increased;the thermally stimulated depolarization current spectrum results show that the introduction of modified functionalized zeolite particles into XLPE increases the trap energy level of the composite material,The number of traps has been increased,thereby improving the DC dielectric properties;XLPE/7wt% TAICS-ZSM-5-HBP nanocomposites have higher thermal conductivity than XLPE at four temperatures,This is due to the high thermal conductivity of hyperbranched polyaramid.In the composite XLPE cross-network structure and TAICS-ZSM-5-HBP modified particles are used as connection intermediates.The number of heat conduction nodes of the composite material is greatly increased,the interface thermal resistance of the heat conduction path is greatly reduced,and the particles are evenly dispersed inside the composite material,The thermal conductivity of composite materials is greatly improved.The thermal conductivity and insulation properties of the modified composite material have been greatly improved due to the introduction of TAICS-ZSM-5-HBP modified zeolite particles,which is of great significance to the development of high-voltage direct current transmission cable materials.