Preparation And Study Of Soft PVC With Thermal Conductivity And Flame Retardancy

The soft PVC(polyvinyl chloride) has been widely used in the fields of wire, cable, artificial leather, electronic appliance and so on because of its good mechanical properties, insulation properties, processing properties, and low cost, etc. However, the application of soft PVC has been limited by its poor thermal conductivity, and the deficiency of flame retardant property decreased due to the addition of plasticizer. The aim of this paper is to improve the thermal conductivity and flame retardant property of soft PVC through means that silica powder with surface organic modify used as thermal conductive filler and magnesium hydroxide or aluminum hydroxide used as flame retardant. The soft PVC with thermal conductivity, flame retardancy and comprehensive performance was prepared by melt blending, and the comprehensive performance of soft PVC were discussed with the help of various tests. The main research contents are as follows:1. A novel silane coupling agent KH-X synthesized with(?-aminopropyl) triethoxy –silane and epichlorohydrin was used to modify the surface of silica powder to improve the dispersion and the compatibility between silica powder and soft PVC resin. The results showed that the oil absorption was reduced effectively and the dispersion of silica powder was uniformed by the use of KH-X.2. The thermal diffusivity and thermal conductivity of the prepared soft PVC melt blended with the modified silica powder were both improved. When the silica powder was less than 20%vol, the thermal conductivity increased slowly; while it was more than 20%vol, the growth rate of thermal conductivity improved significantly. When soft PVC was prepared with silica powder at 40%vol, thermal diffusion diffusivity was 0.44 mm2/s, thermal conductivity reached 0.63 W/(m·K), volume resistivity was 2.1×1012 ?·m, tensile strength was 10.8 MPa, the elongation at break was 109%, shore hardness was 95 A, thermal stability compared with soft PVC without silica powder did not have obvious change.3. Magnesium hydroxide or aluminum hydroxide was added respectively to prepared soft PVC with thermal conductivity and flame retardancy on the basis of silica powder/soft PVC composite as flame retardant. The results showed that the flame retardancy and smoke-suppressant property of soft PVC were both enhanced when the amount of additives was between 25 to 30 phr. To the flame retardancy and smoke-suppressant property of soft PVC, magnesium hydroxide was better than aluminum hydroxide, which is the same in thermal conductivity.4. When soft PVC was prepared with silica powder at 33%vol and magnesium hydroxide at 7%vol, the vertical flame test rating FV-0, the limiting oxygen index was 31.3%, the smoke density was 51, thermal diffusion diffusivity was 0.48 mm2/s, thermal conductivity reached 0.78 W/(m·K), volume resistivity was 8.9×1011 ?·m, tensile strength was 11.5 MPa, elongation at break was 135%, shore hardness was 94 A, the soft PVC still kept a good comprehensive performance.