The Study On The Thermal Conductivity Of Silicon Rubber Based On Nanodiamond Composite Filler

With the development of the integrated,lighter and thinner electronic products,the thermal conductivity of materials is particularly critical.Moreover,a lot of materials in the field(such as electrical and electronic,aerospace and other products)require not only good thermal performance,but also the insulation properties.Silicone rubber can be filled with heat conducting filler to achieve excellent conductivity.Combined with its electrical insulation it becomes excellent thermal conductivity material.However,the single filler has certain limitations in improving the thermal conductivity,therefore,the composite filler is used to optimize thermal performance.The thesis first use nanodiamond/boron nitride(ND/BN)and nanodiamond/alumina(ND/Al2O3)as composite packing to hydroxyl terminated silicone rubber(SR),recpectively.And four ethyl orthosilicate(TEOS)was used as crosslinking agent.We have prepared a series of materials and study their high thermal conductivity and excellent mechanical properties.(1)The thermal conductivity of samples made from 6 wt%ND and 70 wt%BN was 0.82 W/m K,which was increased by 70.83%than that of single 70 wt%BN and 382.35%than the blank base.The mechanical properties of samples made from 1.5 wt%ND and 30 wt%BN were optimized.The results showed that its maximum elongation at break is 246.56%,the tensile strength is 4.36 MPa and the fracture work is 537.50 J/m2.(2)The thermal conductivity of samples made from 6 wt%ND and 80 wt%Al2O3 was 1.25 W/m K,which was increased by 11.6%than that of single 80 wt%Al2O3 and 635.29%than the blank base.So this sample exhibited good thermal conductivity.Besides,its tensile strength is up to 13.30 Mpa,proved to be excellent mechanical properties.The effects of compound packing ratio and different preparation methods on the properties of silicone rubber were investigated.The thermal conductivity,thermal stability and mechanical properties of silicone rubber were analyzed.The results showed that the composites were modified following with finely dispersed,and then a certain amount of hydroxyl silicone oil was added.Thus the samples with higher comprehensive properties were made.The samples with ND/BN and ND/Al2O3 had good thermal stability,and the mechanical properties of the samples were better than those of the existing products from the market.Through the composite filling of ND/BN and ND/Al2O3,the thermal conductivity of silicone rubber was improved obviously.Besides,the mechanical properties were improved,and good thermal stability was achieved.So ND has a broad development prospects in the thermal material.It can be used not only in silicone rubber,but also in other polymers and composite thermal filler.