PP/石墨微片复合材料的制备和性能

Preparation and Properties of Composites PP/Graphite Sheets

分别使用天然石墨用插层-还原法制备膨胀石墨微片(EG)、使用天然石墨用Hummer法制备氧化石墨烯(GO),再使用GO分别由热还原法制备石墨烯片(T-rGO)和化学还原法制备石墨烯片(C-rGO)。将上述三种产物作为填料与PP熔融共混制备出不同填料含量的PP/EG、PP/T-rGO和PP/C-rGO复合材料,用X-射线衍射(XRD)分析、热分析(DSC)、扫描电子显微镜(SEM)、热失重分析(TGA)、拉伸及冲击测试等手段对三种复合材料的结构和性能进行表征,研究了用不同方法制备的石墨微片对复合材料性能的影响。结果表明,当填料EG、T-rGO的含量为0.1%(质量分数,下同)时PP/EG、PP/T-rGO复合材料的拉伸强度达到32.2 MPa和33.5 MPa,分别比纯PP提高了7.2%和11.2%;冲击强度分别比纯PP提高了27.4%和19.6%。当填料C-rGO的含量为0.3%时PP/C-rGO复合材料的拉伸强度和冲击强度分别为37.3 MPa和5.8 k J/m2,较纯PP提高了23.9%和27%。填料EG、T-rGO和C-rGO的加入使PP/石墨微片复合材料的熔融温度、结晶温度和结晶度比纯PP提高,当填料C-rGO的含量为0.1%时PP/C-rGO复合材料的熔融温度比纯PP提高了10.2℃,其结晶度提高了4.2%,这是石墨微片在复合材料中的"异相成核效应"诱导PP分子链的规整性排列引起的。当分别加入含量为0.1%的三种填料时PP/EG、PP/T-rGO和PP/C-rGO复合材料的最大热分解温度分别比纯PP提高了13.5℃、9.1℃和6.9℃,表明加入少量的石墨微片就能使PP的热稳定性明显改善。少量的填料能均匀的分散在基体中,但是加入过量的填料时出现团聚。

As raw materials, expanded graphite （EG） sheets were prepared from natural graphite via intercalation-reduction method, while thermally reduced graphene sheets （T-K30） and chemical reduced grapheme sheets （C-K30） were prepared from graphene oxide （GO）, which was synthesized by Hummers method. Then composites of polypropylene （PP）/graphite sheets were prepared with graphite sheets as fillers and PP as matrix by melt-blending method to produce composites of PP/EG, PP/T-rGO and PP/C-rGO respectively with different filler contents. The structure and properties of the three prepared composites of PP/graphite sheets are characterized by means of X-ray diffractormeter （XRD） , scanning electron microscope （SEM）, thermal analysis （DSC）, thermal gravimetric analysis （TGA）, as well as tensile and impact tests. The results show that the tensile strength of composites of PP/EG and PP/T-rGO with 0.1% of EG or T-tGO, can reach 32.2 MPa and 33.5 MPa, which increased by 7.2% and 11.2%, respectively in comparison with that of the pure PP, while the impact strength of PP/EG and PP/T- rGO composites was improved by 27.4% and 19.6%. The tensile strength and impact strength of the composite PP/C-K30 with 0.3% C-K30 were 37.26 MPa and 37.26 kJ/m^2, respectively, which increased by 23.9% and 27%, in comparison with those of the pure PP. The melting temperatures, crystalline temperatures and crystalline degree of PP/graphite sheet composites were higher than those of the pure PP. In contrast to the pure PP, the melting temperature and crystalline degree of PP/C-rGO composites with 0.1% C-rGO increased 10.2℃ and 4.2%, respectively. It can be attributed to the ＂heterogeneous nucleation effect＂ of graphite sheets, which can induce the regular arrangement of PP molecular chains. The maximum decomposition temperatures of PP/EG, PP/T-rGO and PP/C-rGO composites with 0.1% of graphite sheet showed 13.5 ℃, 9.1 ℃ and 6.9 ℃ respectively higher than that of the pure PP, indicating that the thermal stability of the composites can be improved by adding a small amount of graphite sheets. The fillers have been dispersed homogeneous in the matrix, but agglomeration appeared when excessive fillers were added.