Structure and Melt Rheology of Long-Chain Branching Polypropylene/Clay Nanocomposites
Structure and Melt Rheology of Long-Chain Branching Polypropylene/Clay Nanocomposites
复制标题
长链支化聚丙烯/粘土纳米复合材料的结构和熔体流变学
DOI：
10.1002/app.32800
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发表时间：
2011-01-15
影响因子：
3
通讯作者：
Huang, Han-Xiong
中科院分区：
文献类型：
--
作者：
Su, Feng-Hua;Yan, Jia-Hua;Huang, Han-Xiong
采用双螺杆挤出机熔融共混法制备了长链支化聚丙烯（LCB-PP）/粘土纳米复合材料。这些纳米复合材料的微观结构和熔体流变性进行了研究，采用X射线衍射，透射电子显微镜，振荡剪切流变学，熔体拉伸试验。结果表明，在马来酸酐接枝PP的存在下，粘土层被聚合物分子链插层，并在LCB-PP基体中剥离良好。流变特性，如在低频下较高的储能模量和固体样的tan-omega曲线的平台，表明一个紧凑和稳定的填料网络结构形成时，粘土负载在4 phr（份每百份）或更高。熔体拉伸下的纳米复合材料的响应揭示了一个初始的熔体强度和拉伸粘度随着粘土浓度增加到6 phr的下降。后来，熔体强度和拉伸粘度表现出轻微的增加，进一步增加粘土浓度。这些结果可能是由于LCBPP基质的分子量降低以及LCB-PP分子链插入粘土层中引起的。随着挤出温度的降低，纳米复合材料的熔体强度和拉伸粘度也增加，这是由于在较低的挤出温度下的流动诱导结晶。(C)2010 Wiley Periodicals，Inc. J Appl Polym Sci 119：1230-1238，2011
Long-chain branching polypropylene (LCB-PP)/clay nanocomposites were prepared by melt blending in a twin-screw extruder. The microstructure and melt rheology of these nanocomposites were investigated using x-ray diffraction, transmission electron microscopy, oscillatory shear rheology, and melt elongation testing. The results show that, the clay layers are intercalated by polymer molecular chains and exfoliate well in LCB-PP matrix in the presence of maleic anhydride grafted PP. Rheological characteristics, such as higher storage modulus at low-frequency and solid-like plateau in tan-omega curve, indicate that a compact and stable filler network structure is formed when clay is loaded at 4 phr ( parts per hundred parts of) or higher. The response of the nanocomposite under melt extension reveals an initial decrease in the melt strength and elongational viscosity with increasing clay concentration up to 6 phr. Later, the melt strength and elongational viscosity show slight increases with further increasing clay concentration. These results might be caused by a reduction in the molecular weight of the LCBPP matrix and by the intercalation of LCB-PP molecular chains into the clay layers. Increases in the melt strength and elongational viscosity for the nanocomposites with decreasing extrusion temperature are also observed, which is due to flow-induced crystallization under lower extrusion temperature. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 1230-1238, 2011