高导热定形聚乙烯/石蜡/膨胀石墨相变复合材料的研究

摘要

以高密度聚乙烯(HDPE)作为包覆材料，石蜡作为相变材料，膨胀石墨或鳞片石墨作为导热增强剂，通过熔融共混和热压制备了不同石蜡用量的定形相变储能材料。通过实验分析了所制定形复合储能材料的相变温度、相变潜热、热导率等性能。石蜡经过高密度聚乙烯包覆之后，相变焓值下降30％左右(石蜡含量65％(质量分数))。膨胀石墨和鳞片石墨的加入均能提高复合材料的热导率。膨胀石墨含量为10％(质量分数)时，样品的热导率与无导热增强剂样品相比较提高率为594％，而相同质量分数的鳞片石墨热导率提高率仅为83％。由此可见膨胀石墨对复合材料热导率的贡献远远大于同等质量分数下鳞片石墨的贡献。%Form-stable phase change composites were prepared by melt blending and hot-compaction of paraffin, expanded graphite (EG)or flake graphite (FG)and high density polyethylene (HDPE).In the composites,par-affin served as a latent heat storage material,EG or FG as a heat transfer promoting agent and HDPE as a ma-trix.Phase transition temperatures,latent heat values and thermal conductivity values of the composites were measured.In order to prevent the leakage of melting paraffin in the composites,the minimum weight percent for HDPE was 35%.The latent heat of the composites increased with increasing mass ratio of the paraffin in the composites.EG and FG could improve thermal conductivity of the composites significantly.When the addition of EG was in the ratio of 10wt%,thermal conductivity of the PCM was up to 2.50 W/(m·K),more than 6 times of that without any additives,which was much better than that by addition of FG.