In situ polymerized poly(propylene)/graphene nanoplatelets nanocomposites: Dielectric and microwave properties
In situ polymerized poly(propylene)/graphene nanoplatelets nanocomposites: Dielectric and microwave properties
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DOI：
10.1016/j.polymer.2012.09.018
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发表时间：
2012-10
期刊：
影响因子：
4.6
通讯作者：
V. G. Shevchenko;S. V. Polschikov;P. M. Nedorezova;A. N. Klyamkina;A. Shchegolikhin;A. M. Aladyshev;
中科院分区：
文献类型：
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作者：
V. G. Shevchenko;S. V. Polschikov;P. M. Nedorezova;A. N. Klyamkina;A. Shchegolikhin;A. M. Aladyshev;
采用茂金属催化体系，在丙烯液相中原位聚合制备了等规聚丙烯/石墨烯纳米片复合材料。通过石墨的化学氧化和随后的还原制备石墨烯纳米片。GNP在甲苯中的悬浮液的初步超声处理导致颗粒在液体聚合介质和聚合物基质中的更好分散。GNP颗粒由3-5个石墨烯层组成并且具有40的纵横比。在具有原始GNP颗粒的复合材料中，它们的纵横比为110，而超声处理将纵横比降低至40-50。显然，超声处理提供了更均匀分布的GNP颗粒，其在纳米复合材料中很大程度上是个体化的。填料颗粒及其聚集体的纵横比的这种变化导致具有原始和超声处理的GNP的复合材料的不同性质。具有原始GNP的复合材料的渗滤阈值为0.25体积%。在具有超声处理的GNP的复合材料中，逾渗阈值为2-3体积%。这是由于超声波处理后填料颗粒聚集体的尺寸减小以及颗粒在聚合物基体中更均匀的分布。
Composite materials of isotactic polypropylene and graphene nanoplatelets were synthesized by in situ polymerization in liquid propylene with the use of metallocene catalyst system. Graphene nanoplatelets were prepared by chemical oxidation of graphite and subsequent reduction. Preliminary ultrasonic treatment of GNP suspensions in toluene results in better dispersion of particles, both in liquid polymerization medium and in polymer matrix. GNP particles consist of 3–5 graphene layers and have aspect ratio 40. In composites with pristine GNP particles their aspect ratio is 110, whereas ultrasonic processing reduces aspect ratio to 40–50. Ultrasonic processing provides, apparently, a more uniform distribution of GNP particles, which in nanocomposite are largely individualized. This change of aspect ratio of filler particles and their aggregates results in different properties of composites with pristine and sonicated GNP. Percolation threshold for composites with pristine GNP is 0.25 vol.%. In composites with sonicated GNP percolation threshold is 2–3 vol.%. This is due to reduction in the size of filler particles aggregates and much more uniform distribution of particles in polymer matrix after ultrasonic treatment.