通过过氧化二异丙苯(DCP)引发三官能单体三羟甲基丙烷三丙烯酸酯(TMPTA)对高密度聚乙烯(HDPE)进行熔融接枝改性,同时利用大分子自由基间的偶合反应制备出长支链聚乙烯(LCBPE).转矩曲线和傅里叶变换红外光谱测试表明TMPTA成功接枝到HDPE,解释了熔融支化法制备LCBPE的机理.利用多种流变分析方法,如储能模量、损耗角、Cole-Cole图等方法有效区分了LCBPE和HDPE.采用差示扫描量热和X射线衍射分析技术,研究了引发剂用量对LCBPE结晶性能的影响,结果表明,长支链LCB结构的引入使HDPE的熔点、结晶度和起始结晶温度提高,晶体结构和晶型未发生变化,晶粒尺寸增大.利用热台偏光显微镜对HDPE和LCBPE晶体形态进行分析,发现LCBPE相比HDPE晶核增多,晶体生长速度降低.
Long chain branching polyethylene (LCBPE) was prepared by melt grafting reaction in the presence of dicumyl peroxide (DCP) and trimethylolpropane triacrylate (TMPTA) by mixer.The transient torque curves and Fourier transformed infrared spectroscopy (FT-IR) results indicate that TMPTA is grafted onto HDPE backbone.The mechanism of melt grafting prepared LCBPE was explained.Various rheological plots including storage modulus,loss angle,Cole-Cole plot were used to distinguish LCBPE from HDPE.Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were used to study the influence of initiator content on crystallization property of LCBPE.It is found that LCBPE has higher melting point,degree of crystallinity,crystallization onset temperature and grain size than HDPE.The crystal texture and crystal form of LCBPE have no change compared with HDPE.Furthermore,the crystal morphology of HDPE and LCBPE was observed through polarized optical microscopy (POM).
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