Effect Of End Groups On The Insulation Properties Of Hyperbranched Polyester Modified Nano-SiO₂/Epoxy Resin

With the increasing scale of the power grid,the voltage level has gradually increased.Therefore,in order to better improve the insulation performance of each power equipment,this article first uses the nano-ZnO and SiO2 modified by the coupling agent wet treatment method to fill the EP,and then based on the above,the nano-SiO2 was modified by the coupling agent and the hyperbranched polyester(HBP)with different end group types and number of end groups.Under different hyperbranched modification conditions,the modified nano-SiO2 was modified with the increase of the loading influence on the insulation performance of epoxy resin.The results show:Under the condition of wet modification of coupling agent,the increase of nano ZnO loading will increase the relative dielectric constant of epoxy resin,which can reach 4.89 at 6wt%.Nano-SiO2 makes the relative dielectric constant of the composite material increase with its filling amount,firstly reduced to 3.46 at lwt%and then increased to 3.89 at 6wt%.Nano-ZnO and SiO2 can increase the partial discharge starting voltage of epoxy resin by 61%and 49%,respectively,and the electrical dendrite initiation rates of the two are the lowest at 3wt%and 4wt%,respectively.In terms of thermal conductivity,nano-SiO2 and ZnO can increase the thermal conductivity by 30%and 26%,respectively.With the increase in the number of carboxyl end groups,the better the effect of improving the dielectric properties and thermal conductivity of EP composites.The modification effect is best when the number of end groups is 24:when the filling amount is 5wt%,the partial discharge starting voltage and thermal conductivity are increased by 30.6%and 43.7%respectively compared to pure epoxy resin;when the filling amount is 7wt%,The breakdown field strength is increased by 24.7%compared with pure epoxy resin;when the filling amount is 5wt%,the relative dielectric constant drops to the lowest value of 3.31.At the same time,the improvement effect of KH560 and C102 modification on various properties of the composite material is slightly better than that of KH550 and C102 modification.Under the same number of end groups,the aliphatic hydroxyl-terminated hyperbranched polyester H102 selected in this article is used for the composite materials.The performance improvement effect is slightly better than the aromatic hydroxyl-terminated hyperbranched polyester H302,and the modification effect of the carboxyl-terminated hyperbranched polyester is slightly better than the hydroxyl-terminated group.In summary,the type and number of end groups of hyperbranched polyester will affect its modification effect on the insulation properties of composite materials.