Study On Modification And Performance Of Epoxy Resin/Boron Nitride Thermal Insulation Materials

Epoxy resin is widely used in the field of high-voltage insulation due to its good processability,insulation performance,corrosion resistance and good adhesion.However,with the continuous improvement of the voltage level,the shortcomings of low thermal conductivity and insufficient toughness of epoxy resin are gradually exposed.How to improve the thermal conductivity and toughness of the resin on the basis of ensuring the insulation performance of the epoxy resin so that it can meet the different requirements of different high-voltage electrical equipment for the insulation material and expand its application range is the current research focus in the field of insulation materials.Filled epoxy resin composites can improve the performance of epoxy resin and the process is simple,which has attracted more and more attention.Boron nitride(BN)is an ideal filler with good electrical insulation and thermal stability,low dielectric constant and high thermal conductivity.Based on the functional design of boron nitride/epoxy composite,the effects of BN addition,surface modification and toughening modification on the properties of the composite were studied.Due to its smooth surface,few active groups and poor compatibility with epoxy resin,In this paper,the surface of BN was first covered with a layer of polydopamine by oxidation self-polymerization of dopamine,and then the silane coupling agent KH-560 was used to graft the coated BN..Three kinds of fillers were obtained,and BN/EP,DBN/EP,k-DBN/EP composites were successfully prepared.The changes of properties of the composites were systematically explored.The study found that surface modification can improve the properties of composites.With the addition of BN,the thermal conductivity of the composites gradually increased.When the BN content was 30wt%,When the BN content is 30wt%,the thermal conductivity of the modified k-DBN/EP composite is 0.892 W/m·K,which is 25.3%higher than that of the unmodified BN/EP composite,compared to Pure epoxy resin,which has been improved by 355%.The thermal stability of the composite material improves with the increase of the BN content.At the same time,the composite material has more excellent dielectric properties.The breakdown strength also improves to a certain extent when the BN content is 20wt%but the mechanical properties of the composite material decrease obviously,the surface modification does not improve the mechanical properties significantly.Aiming at the shortcomings of the decline in the mechanical properties of composite materials,this article conducts research on toughening of composite materials.The carboxyl-terminated nitrile rubber(CTBN)was used to toughen the composite,by blending with resin and boron nitride,the CTBN toughened composite was successfully prepared.The properties of composites after CTBN addition were explored.Studies show that CTBN can form sea-island structures to toughen the composites.When the content of CTBN is 10-15wt%,the composites show the best balance of properties,and the toughness is increased by 30%,and has a higher glass transition temperature and thermal stability,and the breakdown strength of the composite material has improved.