Preparation And Properties Of Boron Nitride/Epoxy Resin Composites And ?-ray Radiation Effect On Their Properties

Epoxy resin composites have been widely used in aerospace and electronics fields.However,there are some performance shortcomings of traditional epoxy resin,such as poor thermal conductivity and poor radiation resistance.With excellent thermal conductivity and high efficiency to transfer heat,boron nitride(h-BN)has broad application prospects in the nuclear science field.Thus,it is of great significance to incorporate boron nitride into the epoxy resin matrix to explore the performance effect of boron nitride on the epoxy matrix,and to study its y-ray radiation effect.In this work,boron nitride/epoxy resin composites were selected as research objects.We carried out research work from three aspects,namely the preparation and characterization of silixane modified boron nitride nanosheet(SiO-BNNS),the preparation and performance study of silixane modified boron nitride nanosheet/epoxy(SiO-BNNS/EP)composites,and the effects of y-ray on the properties of boron nitride/epoxy(h-BN/EP)composites.The main achievements are listed as follows:1.We investigated the effect of dry mechanical ball milling method on the exfoliation and surface mofication of h-BN.The results showed that,dry mechanical ball milling under nitrogen atmosphere could exfoliate h-BN,to obtain the BNNS with a thickness as low as 4 nm.At the same time,hydroxyl groups could be introduced onto the surface of h-BN and continue to react with the silane coupling agent APTES to achieve the preparation of SiO-BNNS.The TGA curves showed that its weight loss rate could reach 14.2%at 800?.2.With SiO-BNNS and h-BN as fillers,SiO-BNNS/EP and h-BN/EP composites were prepared by thermal curing molding,and the effects of filler type and content on the properties of epoxy resin matrix were investigated.The results showed that compared with the raw h-BN,SiO-BNNS nanoparticles showed better dispersibility in the epoxy resin matrix and the agglomeration phenomenon was weakened,which leaded to better improvement effect on the mechanical property and thermal conductivity of the epoxy resin matrix.A small amount of filler could enhance the mechanical properties of the epoxy resin matrix,while too much filler would lead a decrease of the mechanical strength.At the content of 0.052 wt%SiO-BNNS,the tensile strength could be as high as 88.2 MPa,increasing by about 4.6%comparing to pure EP.The thermal conductivity increased with the SiO-BNNS content.At the content of 9.41 wt%SiO-BNNS,the thermal conductivity could reach up to 0.216 W/(m·K),which was 75.6%higher than that of pure EP.3.The effects of 60Co ?-ray irradiation on the structure and properties of h-BN powder and h-BN/EP composites were investigated.The results showed that h-BN powder had good structure and thermal stability under y-ray radiation when the absorbed dose was up to 380 kGy.However,the glass transition temperature and the initial thermal decomposition temperature of h-BN/EP composites were significantly lower than those of pure EP matrix after irradiated by y-ray.The effect of y-ray radiation on the mechanical properties of h-BN/EP composites depended on both the h-BN content and the absorbed dose.For the composite with a low h-BN content(<0.52 wt%),the tensile strength decreased remarkably even after the composite was irradiated by ?-ray at a lower absorbed dose(?180 kGy).Instead,as for the composite with a higher h-BN content(?0.52 wt%),the tensile strength increased significantly after the?-ray radiation at a same absorbed dose(?180 kGy).When the absorbed dose was up to 1000 kGy,the tensile strengths of the irradiated pure EP and all irradiated h-BN/EP composites had a same level.