Preparation And Properties Of Natural Rubber/Silicone Rubber/Alumina Ternary Thermal Conductive Composites And Its Finite Element Simulation

The thermal conductivity of the polymer relates to its application in many fields.Research on thermal Silicone Rubber have been conducted extensively for decades.The thermal conductivity of Silicone Rubber is only 0.2w/m·K,and its mechanical properties are poor as well.The existing thermal Silicone Rubber need to add a large volume fraction of thermal filler into the matrix,which will further reduce its mechanical properties.The microscopic structure of the polymer has a great influence on the properties of the material,the addition of conductive fillers to incompatible polymers has been proved to form double percolation structures,effectively reducing the percolation threshold of the composite.It helps to enhance the conductivity of the polymer.Electric Conduction and thermal conductivity are similar in some conduction mechanisms.If another phase is introduced into the polymer matrix that is incompatible with silicone rubber,it’s possible to form similar double percolation structures,which leads to an improved thermal conductivity.In this paper,based on the above principle,Natural Rubber was introduced as one of the matrix,mixing with the Silicon Rubber,and the Natural Rubber/Silicone Rubber/Alumina Ternary Thermal Conductive Composites was prepared.We changed the blending sequences and mixture ratio of Natural Rubber and Silicon Rubber,then the Al2O3 presented different distribution in the blend matrix,and the morphology of the blend was observed by scanning electron microscope.The effect of filler distribution and microscopic structure of the blend on the thermal conductivity was analyzed.The study shows that the blending of natural rubber,silicon rubber and filler with different mixing sequence led to a great difference between the polymer phase structure and filler distribution,when the Natural Rubber was mixed with filler first,the thermal conductivity is 30% higher than other two blending sequences.When the ratio of the volume fraction of natural rubber and silicon rubber is 40/40,50/30,the blends obtained double-percolation structure,leading to a higher thermal conductivity.In this paper,the effects of filler content and particle size on the thermal conductivity and mechanical properties of the composites were also studied.With the increase of the content of Al2O3 in the system,the thermal conductivity was improved while the tensile strength and the elongation at break were decreased.With the increase of particle size of Al2O3,thermal conductivity and mechanical properties are both reduced.In this paper,the anti-aging agent4010 NA was used to improve the aging resistance of the composites.It was found that when the composites was aged at 100℃for 7 days,the tensile strength and elongation at break werekept more than 60%.In this paper,ANSYS software is used to model the ternary composites and the finite element analysis were carried out.The results show that the thermal conductivity calculated by the finite element model is basically the same as the experimental data.