Preparation And Properties Of Filled Thermal Conductive PP-based Composites

Polypropylene composite of thermal conductivity is a new functional polymer composite, with a wide application prospect in the field of heat conduction and heat radiation. This paper takes improving the thermal properties of polypropylene (PP), which means improving the thermal conductivity of composite materials as the purpose, and uses the percolation theory and double percolation theory of conducting high polymer composites for reference, to analyze the application of percolation theory and double percolation theory in thermal behavior of thermal conductive polymer composites. By using two kinds of PP composites with different types, of which one is Styrene-Ethylene-Butadiene-Styrene block copolymer (SEBS), better compatible with PP, and the other is polyamide 6 (PA6), a composite system composed of PP/SEBS and PP/PA6, poor pcompatibility with PP, the paper researches the influence of selective distribution of conductive carbon black and conductive filler in the complex system on electrical conductivity and thermal conductivity.The first chapter of this thesis counted experimental materials, experimental apparatus and test standards used in this paper, and described in detail the experimental scheme, the preparation of samples and the test methods. It also designed L34 orthogonal experiment of the PP/SEBS composite system.The second chapter of the thesis designing L9(34) orthogonal experiment of the PP/SEBS composite system, to explore the effects of PP/SEBS ratio, oil content, feeding mode and the content of carbon black on the conductivity, so as to get the optimal scheme and verify it. Firstly filled with conductive carbon black (CB) to analyze the conductive behavior and thermal behavior of PP/SEBS/CB composites and to further verify the optimal scheme of orthogonal experiment; and then with thermal insulation fillers of ZnO and Al2O3 in PP/SEBS composite system to research and analyze the thermal behavior and mechanical property of composite materials; remixing thermal conductive fillers on the basis of this to study the performance of composite materials. The results show that: the conductive behavior of PP/SEBS/CB composites is a typical percolation phenomenon, the volume resistivity of the composites declines substantially when the amount of CB reaches the critical value, and SEBS is effective in reducing the percolation threshold of CB dosage in composite percolation mutation. The thermal effect of thermal insulation composite material of PP is that:ZnO filling is better than Al2O3; the system of PP/SEBS is better than that of the pure PP matrix; and in PP/SEBS composites system, study finds optimal thermal conductivity and mechanical properties of single ZnO filling in different filler compound effects.The third chapter of this thesis taking PP/PA6 as matrix, firstly filled conductive CB for the analysis of conductive behavior and thermal behavior of PP/PA6/CB composites, and the effect of macromolecular compatilizer on electrical properties and thermal conductivity of composite materials; and then filled ZnO in PP/PA6 composites to research and analyze the thermal behavior of composite materials and the effect of macromolecular compatilizer on the electrical conductivity and thermal conductivity of composite materials; remixing conductive fillers on the basis of this to study the performance of composite materials. The results show that:the conductive behavior of PP/PA6/CB composites is a typical percolation phenomenon; PA6 is effective in reducing percolation threshold of CB dosage in the composite percolation mutation, but the effect is not as good as that of PP/SEBS composite system; macromolecular compatilizer of Maleic Anhydride Grafted PP (PP-g-MAH) added is not conducive to the conductive properties of the composite, but it stabilized the conductive channel; PP/PA6/ZnO composite thermal conductivity is better than that of PP/SEBS/ZnO composite materials; Study on synergistic effects of thermal conductivity of different fillers found optimal coefficient in single ZnO filler. SEBS-g-MAH instead of PP-g-MAH can improve the impact properties of composite materials, but the thermal conductivity will decrease. The use of 10 wt% silicon aluminum composite nanotube (PNT) instead of the equivalent ZnO will further enhance the impact strength and VEKA softening temperature of the composites.