Preparation And Properties Of The Thermal Conductive Natural Rubber

Natural rubber has a series of excellent physical and chemical properties,and is widely used in transportation,medical and health,military and national defense fields.However,the thermal conductivity of natural rubber is generally not high,which limits its breadth and depth of application in certain fields.For example,in the field of electronic packaging,natural rubber composite materials with good thermal conductivity and mechanical properties are of great significance for solving the heat dissipation problem of precision electronic equipment.In addition,the problem of heat dissipation of tires is also an urgent problem to be solved in the field of transportation.It is particularly important for the further development of the transportation industry to improve the thermal conductivity of tires without damaging the mechanical properties.Therefore,it is very necessary to improve the thermal conductivity of natural rubber and prepare natural rubber composites with good thermal conductivity and mechanical properties.In this paper,from the three perspectives of preparation of thermally conductive particles,modification of thermally conductive particles,and structure of thermally conductive particles,thermally conductive natural rubber composite materials were prepared by filling particles in rubber.Firstly,the ultrasonic solvent-assisted stripping method was used to successfully prepare thermally conductive hexagonal boron nitride nanosheets with complete crystal structure and smooth and transparent surface.The influence of the content of hexagonal boron nitride nanosheets on the thermal conductivity of natural rubber was investigated.Secondly,the hexagonal boron nitride nanosheets were surface modified from different angles,and the effects of different particle modification methods on the thermal conductivity of natural rubber materials were explored.Finally,graphene oxide and hexagonal boron nitride nanosheets were used to prepare composite particles with a special two-dimensional network structure.The composite particles are added to natural rubber to prepare a natural rubber composite material with excellent thermal conductivity and mechanical properties.The main experimental content and research results are as follows:(1)Using ultrasonic solvent-assisted stripping method to successfully prepare hexagonal boron nitride nanosheets at room temperature,the effects of stripping solvent and stripping time on the crystal structure and surface morphology of hexagonal boron nitride nanosheets were investigated,and the best process for preparing hexagonal boron nitride nanosheets was determined.The results show that using ethanolamine as the solvent,peeling at room temperature for 12 h can produce hexagonal boron nitride nanosheets with a lateral dimension of 176 nm,a thickness of 3nm,a complete crystal structure,and a smooth and transparent surface.Compared with the unstripped bulk hexagonal boron nitride,this nanosheet can be better dispersed in natural rubber and has better compatibility with natural rubber.This nanosheet increases the thermal conductivity of natural rubber by 48.60%,the tensile strength by 26.34%,and the tear strength by 30.43%.(2)The surface modification of hexagonal boron nitride nanosheets was successfully achieved from different angles.Starting from the perspective of improving the dispersion of particles in latex,the surface modification of hexagonal boron nitride was achieved using dopamine.Starting from the perspective of improving the interaction between the filler and the matrix,the surface modification of the hexagonal boron nitride nanosheets was achieved using the silane coupling agent KH570.Then the effects of the two modified particles on the thermal conductivity and mechanical properties of natural rubber are comprehensively compared.It was finally determined that the silane coupling agent KH570 modified particles had better thermal conductivity and mechanical properties of natural rubber than dopamine modified particles.The thermal conductivity of the composite material prepared with KH570 modified particles is 0.39 W/m·K,the tensile strength is 20.14 MPa,and the tear strength is 27.54 N/mm.Compared with the composite material filled with unmodified particles,the thermal conductivity increased by 26.54%,the tensile strength increased by 31.21%,and the tear strength increased by 23.78%.(3)Hexagonal boron nitride nanosheet-graphene oxide composite particles were prepared by modifying the surface of hexagonal boron nitride nanosheets and controlling the ratio of different particles.Surface modification allows different particles to be connected by covalent bonds.Controlling the particle ratio makes the composite particles have a special twodimensional network structure.This composite particle can effectively reduce the interface thermal resistance of filler-filler and filler-matrix,form more thermally conductive networks,improve the thermal conductivity of the material,and also have a more obvious effect on the improvement of mechanical properties.The thermal conductivity of the composite material prepared by using such composite particles can reach 0.49 W/m·K,the tensile strength is 25.52 MPa,and the tear strength is 31.54 N/mm.Compared with the composite material filled with a single hexagonal boron nitride nanosheet,the thermal conductivity,tensile strength,and tear strength were increased by 53.48%,56.18%,and 41.25%,respectively.This material has excellent thermal conductivity and mechanical properties.