纳米碳酸钙和纳米蒙脱土对LLDPE结晶行为的影响

Effect of nano-calcium carbonate and nano-montmorillonite on crystallization behavior of LLDPE

通过熔融共混法制备线性低密度聚乙烯(LLDPE)/纳米碳酸钙(nano-CaCO3)和LLDPE/纳米蒙脱土(nano-MMT)复合材料。采用小角激光散射(SALS)、差示扫描量热(DSC)、X射线衍射(XRD)和扫描电镜(SEM)研究了LLDPE的结晶诱导时间、结晶速率和晶体尺寸。结果表明,随着nano-CaCO3和nano-MMT的加入,LLDPE的结晶诱导时间和半结晶时间缩短,且LLDPE/nano-CaCO3复合材料的诱导时间和半结晶时间较LLDPE/nano-MMT复合材料的短。nano-CaCO3和nano-MMT使得LLDPE的微晶尺寸变小,但晶胞参数变化不大。利用Kissinger方法计算结晶活化能发现,LLDPE/nano-CaCO3复合材料的结晶活化能最低。通过SEM分析发现,nano-CaCO3在LLDPE中的分散比nano-MMT更均匀。

The linear low density polyethylene （LLDPE）/nano-calcium carbonate （nano-CaCO3） and LLDPE/nano-montmorillonite （nano-MMT） composites were prepared by the melting mixing method. The crystallization behavior, including the crystallization induction time, crystallization rate, spherulite size and crystal structure of LLDPE composites were investigated using the small angle light scattering （SALS）, differential scanning calorimetry （DSC）, X-ray diffraction （XRD） and scan- ning electron microscope （SEM）. The results indicated that with the addition of the nano-MMT and nano-CaCO3 ,the crystallization induction time and half crystallization time of LLDPE were greatly shortened, and the crystallization induction time and half crystallization time of LLDPE/nano-CaCO3 composite were shorter than those of LLDPE/nano-MMT composite. The microcrystal size of LLDPE was also decreased with the increase of nano-CaCO3 and nano-MMT content,however there was little change in cell parameters. Using Kissinger method to calculate the activation energy of crystallization, LLDPE/nano-CaCO3 composite had the lowest activation energy. The SEM analysis showed that the dispersion of nano-CaCO3 in the LLDPE was more uniform than that of nano-MMT.