云母粉改性高密度聚乙烯的汽油阻隔性

摘要

以片状云母粉为阻隔改性剂,与高密度聚乙烯(PE-HD)熔融共混,以改善其对汽油的阻隔性,考察云母粉形貌、含量等因素对PE-HD/云母粉复合材料阻隔性、熔体流动性以及力学性能的影响.结果表明,云母粉可显著提高复合材料对汽油的阻隔性,但熔体流动速率(MFR)与断裂伸长率降幅明显,高径厚比的云母粉对复合材料的汽油阻隔性提升更为显著,但径厚比过大不利于阻隔性的进一步提升,并会导致材料MFR和断裂伸长率进一步下降;当云母粉含量开始增加时,复合材料的汽油阻隔性明显提升,拉伸强度与缺口冲击强度上升,而MFR和断裂伸长率下降,当裂纹发展方向垂直于云母片面积方向时,缺口冲击强度提高更为显著;随着云母粉含量继续增加,复合材料的汽油阻隔性趋于稳定,拉伸强度与缺口冲击强度却明显下降.当径厚比为180的云母粉质量分数为30%时,复合材料具有最佳的综合性能,其汽油浸泡后的拉伸强度保持率显著高于纯PE-HD.%Mica powder with the micro morphology of sheet was adopted as barrier modifier and blended with high density polyethylene (PE-HD) through melting extrusion for improving the gasoline barrier properties of PE-HD. The effects of morphol-ogy and content of the mica powder on the barrier properties,melt fluidity and mechanical properties of the PE-HD/mica powder composites were studied. The results show that the mica powder can improve the gasoline barrier properties of the composites sig-nificantly,but the melt flow rate (MFR) and elongation at break decrease obviously,the gasoline barrier properties are improved more significantly when the diameter-thickness ratio of the mica powder is higher,but if the diameter-thickness ratio is too high,the barrier properties can not be improved further,MFR and elongation at break also decrease further. When content of the mica powder begins to rise,the gasoline barrier properties of the composites are improved remarkably,the tensile and notched impact strength are increased,MFR and elongation at break are decreased,when the direction of crack growth is perpendicular to the area direction of mica sheet,the notched impact strength is improved more obviously. When content of the mica powder continue to rise,the gasoline barrier properties tend to be stable,the tensile and notched impact strength are decreased obviously. When the mass fraction of mica powder with 180 of diameter-thickness ratio is 30%,the composite has best comprehensive properties and the tensile strength reten-tion rate after gasoline soaking is more higher than that of pure PE-HD.