Preparation And Properties Of BN-Al₂O₃ Modified Epoxy Resin Composites

Epoxy resin(EP)is a thermosetting resin with excellent performance,which is widely applied to the field of electronic packaging and printed circuit tubing.The heat dissipation performance of epoxy resins has been proposed with higher requirements because of the development of electronic components towards miniaturization,integration and high frequency.The modified epoxy resin hybrided with inorganic nanomaterials has been a hot research topic.Boron nitride(BN)has several excellent properties,such as high thermal conductivity,low coefficient of thermal expansion,high electrical insulation,good dimensional stability and chemical stability.The mechanical,thermal and dielectric properties of EP composites can be enhanced by the introduction of modified BN(m BN),which is attributed to the improved compatibility between m BN and EP matrix.As a result,BN/EP composites have received wide attention.In this paper,modified BN(m BN)was prepared by surface modification of BN with sodium hydroxide solution and 3-aminopropyltriethoxysilane,following which the EP composites reinforced with m BN were synthesized.The effects of m BN and loading amounts on the properties of BN/EP composites were investigated.As reaction of polar functional groups grafted onto the surface of m BN with the EP matrix enhanced the interfacial interaction,the mechanical properties and dielectric strength of m BN/EP composites were greatly improved with 5 wt%m BN.The impact and bending strengths are 134 MPa and 19.2 k J·m^-2,which are 67.5%and 284%higher than those of pure EP,respectively.The dielectric strength is 19.8 k V/mm,which is131%higher than that of pure EP.Furthermore,the thermal conductivity and thermal stability of m BN/EP composites are also significantly enhanced.The 5 wt%m BN/EP composites show a thermal conductivity of 0.247 W/(m·K),which is 31%higher than that of pure EP.The m BN-m Al₂O₃/EP composites were prepared to further improve the properties of m BN/EP composites.After that,the morphology of m BN-m Al₂O₃hybrids and m BN-m Al₂O₃/EP composites,the mechanical,thermal and dielectric properties of m BN-m Al₂O₃/EP composites were characterized.The results show that m Al₂O₃ is successfully attached to the m BN surface,and the introduction of m BN-m Al₂O₃ hybrids enhanced the interaction between the interface of m BN-m Al₂O₃ hybrids and EP matrix,improves the mechanical and dielectric properties of EP composites.The impact and bending strengths of the 5wt%m BN-3 wt%m Al₂O₃/EP composites are 142.67 MPa and 22.94 k J·m^-2,which are6.5%and 19.5%higher than those of 5 wt%m BN/EP composites,respectively.The dielectric strength is 22.87 k V/mm,which is 15.5%higher than that of the 5wt%m BN/EP composite.The dielectric loss of m BN-m Al₂O₃/EP composites does not change obviously.Although the dielectric constant is slightly higher than that of pure EP,it still meets the requirements of the electronic packaging field.The thermal conductivity of the 5 wt%m BN-3 wt%m Al₂O₃/EP composites is0.346 W/(m·K),which is 40.1%higher than that of 5 wt%m BN/EP composites,as the thermal conductivity of BN and Al₂O₃ is significantly higher than that of EP,and that the thermal network between m BN-Al₂O₃ and EP is formed in the EP matrix.The thermal stability of the m BN-m Al₂O₃/EP composites is better than that of the m BN/EP composites,as m Al₂O₃ prevents the decomposition of unstable functional groups on the m BN surface,which led to the further improvement of the thermal stability of EP composites.