相变辅助PE-LD/EG共混物制备与性能  

Properties of phase change assisted preparation of low density polyethylene/expanded graphite composites

作　　者：黄军元 尹艳平 HUANG Junyuan;YIN Yanping(Swell Marui(Guangzhou)Automobile Parts Co.,Ltd.,Guangzhou 510530,China)

机构地区：[1]四维尔丸井(广州)汽车零部件有限公司,广州510530

出　　处：《工程塑料应用》2024年第3期45-49,共5页Engineering Plastics Application

基　　金：广东省自然科学基金项目(2021A1515010487)

摘　　要：针对层状填料在聚合物基体中剥离与分散困难的问题,将水引入层状填料层间并冷冻成冰,相同质量的水从液态变为固态体积增大,使填料的层间距增大,在熔融共混过程中,高温作用下填料层间的冰迅速转变为水蒸气并产生瞬时高压,进而实现层状填料的原位剥离;由此提出一种相变辅助熔融共混制备低密度聚乙烯(PE-LD)/膨胀石墨(EG)复合材料的新工艺方法,研究新工艺对复合材料微观形貌、结晶性能和导热性能的影响。相变辅助制备的PE-LD/EG复合材料的扫描电子显微镜图像呈现出更薄的片材堆叠结构,X射线衍射线表现出更低的(002)衍射峰强度,说明相变效应可以有效地促进EG的原位剥离;动态扫描量热分析结果表明,剥离后的EG片层可以作为异相成核点促进PE-LD结晶,复合材料的结晶度从23.47%提高到28.44%;导热性能测试结果表明,PE-LD/EG复合材料的热导率随EG含量的增加而增加,且相变辅助制备的复合材料热导率大于常规熔融共混制备,最大值达0.715W/(m·K)。引入相变效应制备的PE-LD/EG复合材料中的EG剥离程度更高,分散效果更好,有助于EG片层相互搭接形成导热通路,从而提高复合材料的导热性能。Aiming at the difficulty of exfoliating and dispersing layered fillers in polymer matrix,water is introduced into the layers of the layered fillers and frozen into ice.The volume of water with the same mass increases from liquid to solid,which increases the layer spacing of the fillers.In the process of melt blending,the ice between the layers of the fillers is rapidly transformed into water vapor under the action of high temperature and instantaneous high pressure is generated,thus achieving in-situ stripping of the layered fillers.Based on this principle,a new process for preparing low density polyethylene(PE-LD)/expanded graphite(EG)composites with phase transition assisted melt blending was proposed.The effects of the new method on the micro‐morphology,crystalline properties and thermal conductivity of the composites were investigated.The scanning electron microscope images of the phase change assistant PE-LD/EG composites show thinner sheet stack structure and lower(002)diffraction peak intensity,which indicate the phase transition effect can effectively promote the in-situ exfoliation of EG.Dynamic scanning calorim‐etry results indicate that the exfoliated EG layers can be used as heterogeneous nucleation point to promote the crystallization of PE-LD,the crystallinity of the composite was increased from 23.47%to 28.44%.The thermal conductivity test results show that the thermal conductivity of PE-LD/EG composite increases with the increase of EG content,and the thermal conductivity of the phase change assisted composite is higher than that of the conventional melt blend preparation,with a maximum value of 0.715 W/(m·K).EG in PE-LD/EG composite prepared by introducing phase change assistant effect has higher stripping degree and better dispersion effect,which helps to form a thermal conductivity path between EG sheets and improve the thermal conductivity of the composites.

关 键 词：相变作用 原位剥离 膨胀石墨 低密度聚乙烯 热导率 

分 类 号：TB332[一般工业技术—材料科学与工程]