Study On The Preparation And Properties Of Epoxy Resin/Cyanate Ester Thermal Conductive And Electrical Insulating Composites

Traditional polymer matrix composites have been widely used in scientific and industrial fields because of their various excellent properties.However,filling polymer composites with different types of thermal conductive filler can effectively improve their thermal conductivity.In this paper,hexagonal boron nitride?h-BN?and acid-treated carbon nanotube?MCNTs?were used as filler.Meanwhile,cyanoate ester and epoxy resin copolymer were used as matrix material,and the composites can meet more stringent industrial requirements and more advanced industrial production.The composites were prepared by melt prepolymerization and high temperature solidification.At the same time,the heat resistance and dynamic mechanical behavior of the composites were also investigated by the mass ratio of CE/EP and the filling amount of h-BN/MCNTs composite fillers.The effects of thermal conductivity,dielectric properties and micromorphology are as follows:?1?In the curing process of catalyst CE and EP with imidazole,when the ratio of CE/EP is 5/5,EP can quickly open the ring and take place the polymerization reaction with CE.Meanwhile,activation energy of curing reaction decreased and reactions are more likely to occur.As the inorganic fillers,h-BN and MCNTs have no catalytic effect in the curing reaction.However,a certain amount of active groups attached to the surface of h-BN and polar groups such as carboxyl groups and hydroxyl groups bonded to the surface of MCNTs plays a catalytic role in the reaction.?2?When a large amount of h-BN is introduced into the system,the curing reaction of CE/EP will be hindered to some extent,and the degree of cross-linking of the polymer will be reduced,resulting in the decrease of the storage modulus and glass transition temperature?T_g?of the composite.When the content of h-BN is 40wt%and the content of MCNTs is 0.3wt%t⁰.4wt%,the storage modulus of the composite material increased significantly and the glass transition temperature?T_g?also increased.?3?The dielectric constant of CE/EP-5/5 is the highest and it is about 4.05,and the dielectric constant also does not change significantly with frequency.With the h-BN increases,the dielectric constant and dielectric loss of the composite increase.With the addition of MCNTs,a large amount of induced charges are generated inside the composite material,the dielectric constant of the composite material increases,and the dielectric loss decreases.However,the average volume resistivity of CE/EP/h-BN/MCNTs composites is less than 109?·cm^-1,which maintains excellent insulation properties.?4?When h-BN is the only thermal conductive filler in the system,the higher the content of h-BN is,the higher the thermal conductivity of the composite is.When the content of h-BN is 50wt%,the thermal conductivity is 0.689W/mK.When h-BN/MCNTs binary composite fillers were added to the system,the higher the MCNTs content is,the higher the thermal conductivity of the composites is.When the content of MCNTs is 0.5wt%,the thermal conductivity of the composite is 0.75W/mK.The data calculated by the Agari model show that MCNTs possess a better ability to form a thermally conductive path in the resin matrix compared to h-BN.?5?The thermal decomposition temperatures of CE/EP polymers are mostly above340^oC and have good thermal stability.With the increase of h-BN content,the thermal stability of the final polymer increased to a certain extent,and the char yield decreased.However,the final thermal decomposition temperature did not change much,and both were basically stable at 340°C.Moreover,with the addition of MCNTs,the decomposition temperatures of the polymer is greatly increased,and they are basically all above 375°C,and indicating better thermal stability.