离子聚合物改性木粉/HDPE复合材料流变特性

Rheological properties of wood flour/HDPE composites modified by ionomer

为了提高木塑复合材料(WPC)的加工流动性能,利用离子聚合物改性WPC,通过HAAKE Minilab微量混合流变仪研究了离子聚合物改性木粉/高密度聚乙烯(HDPE)的毛细管流变特征。结果表明:添加与未添加离子聚合物的木粉/HDPE均为非牛顿流体中的假塑性流体,均呈现出"剪切变稀"的效应;随着钠离子聚合物含量的增加,改性木粉/HDPE的剪切应力和表观黏度均随着剪切速率的增大呈现降低的趋势,表明钠离子聚合物的加入可以显著改善聚合物熔体的流动特性;添加4wt%的钠离子聚合物和4wt%的锌离子聚合物的木粉/HDPE剪切应力和表观黏度均要低于添加4wt%的偶联剂马来酸酐接枝聚乙烯(MAH-g-PE)的WPC的值,表明与MAHg-PE相比,离子聚合物更能够改善WPC的流动性能,减小熔体流动时HDPE与木粉之间的摩擦阻力;SEM分析表明,添加离子聚合物后HDPE塑料对木粉有很好的包覆效果,没有明显的界面缝隙,且在WPC断面上存在大量的毛刺纤维。

In order to improve the processing flow performance of wood plastic composites(WPC),the capillary rheological properties of the wood flour/high density polyethylene(HDPE)composites modified by ionomer were studied by using a HAAKE Minilab rheometer.Results show that the wood flour/HDPE melts are all pesudoplastic fluid with or without ionomer,which all show the shear thinning effects.Both the shear stress and apparent viscosity of wood flour/HDPE modified by ionomer show the decline trends with the increasing of sodium ionomer and shear rate,which indicates the addition of sodium ionomer could improve the flowability of HDPE melts obviously.The shear stress and apparent viscosity of wood flour/HDPE adding 4wt%sodium ionomer and 4wt%zinc ionomer are both lower than those of the wood flour/HDPE composites adding 4wt%coupling agent maleic anhydride grafted polyethylene(MAH-g-PE),which demonstrates ionomer could improve the flowability of WPC melt much more compared with MAH-g-PE,and decrease the frictional resistance between HDPE and wood flour as melt flows.SEM analysis shows that HDPE polymer has a good coated effect on wood flour after being added ionomer without clear gap between wood flour and HDPE matrix.In addition,there exists a large number of fibrils on the fracture surface of WPC.