| Lately, the carbon series materials used as filler in the polymer to prepare the thermal conductive composite has caused great concern to the general public. But the problem of low thermal conductivity, the improvement of the thermal properties and mechanical properties should be solved to adapt to the currently urgent demand for high-performance thermal conductive materials in most electrical industries. Accordingly, a tentatively innovation using multi-walled carbon nanotubes(MWNTs) filled polypropylene resin(PP) was put forward to prepare the high-performance thermal conductive composite based on taking thermal conductivity as the main index to optimize the matching. Then a further development was obtained by adding other materials, combined with the existing processing equipment and advanced testing instruments to prepare and test the thermal properties and mechanical properties of the composites. Finally, a comparative method was taken to explore the best ratio of formula. The basic work are as follows:1. At first, the PP/MWNTs composites with different ratios of MWNTs and PP was prepared by a novel non-twin screw extruder. Then, the test sample was preparation to examine the related performance indicators. By compared with the thermal performance(thermal conductivity, thermal weight loss and Thermo-gravimetric rate, melt flow rate) and mechanical properties(tensile strength, and impact strength) of the composites, and combined with the section microstructure to analyze the impact of different ratios of MWNTs and PP on the composite materials. The highest thermal conductivity of the composite obtained from the formation design was 0.573 W/(m· K), which increased by 123% compared with pure PP.2. Take the above-mentioned proportion as the basic formula, the PP/KPEG/MWNTs thermal conductive composites were prepared, which took KPEG(before the expansion graphite) and MWNTs mixture as fillers and keep the total amount unchanged, to study the various performance of different ratio composite materials. By this way, the thermal conductivity of the composite can be up to 1.101 W/(m· K), which increased 92% compared with the PP/MWNTs composite. Then the PP/EG/MWNTs composite was prepared by used of EG/MWNTs mixture as fillers, which EG(after the expansion graphite) was obtained by KPEG expended from the muffle furnace where the temperature is 800 ℃or 900℃. By compared the various properties of the two kinds composite, the higher thermal conductivity is 1.51 W/(m· K), which increased by 37% compared with the PP/KPEG/MWNTs. And the reason of the improvement was analyzed by the section microstructure of the composites.3. Amylose and-cyclodextrin were used respectively as synergistic agent to enhance the properties of the PP/KPEG/MWNTs composite, and the thermal properties and mechanical properties of the composites were analyzed to compare the impact of two kinds of synergists on the original composite materials. According to the experiment, though KPEG didn’t take heat expansion, but after the two kinds of polysaccharide filler adding into the materials, the thermal conductivity of the composites still could reach 1.387 W/(m· K) and 1.420 W/(m· K), which increased by 26% and 29% respectively compared with PP/KPEG/MWNTs. Moreover, the improvement of the thermal conductivity was amplified by combined with the cross-section microstructure of PP/KPEG/MWNTs composites.In brief, this paper on the basis of fully considering the MWNTs and PP materials properties, combined with different formula design and process method, a novel thermal conductive composite was prepared and the thermal conductivity improved significantly, which the maximum value could be 1.51W/(m· K) and increased by 487.5% compared with pure PP. The results of the study, to some extent, break through the limitation of thermal conductivity for most of the traditional thermal conductive composites. There is an important practical significance to apply this study in the required fields.
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