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首页> 外文期刊>Journal of Applied Polymer Science >Characterization of Metallocene Ethylene-1-Octene Copolymers with High Comonomer Content Cross-linked by Dicumyl Peroxide or b-Radiation
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Characterization of Metallocene Ethylene-1-Octene Copolymers with High Comonomer Content Cross-linked by Dicumyl Peroxide or b-Radiation

机译：过氧化二枯基或b-辐射交联的高共聚单体含量的茂金属乙烯-1-辛烯共聚物的表征

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摘要

Two metallocene ethylene-1-octene copolymers differing in comonomer content were cross-linked either by dicumyl peroxide (DCP) or b-radiation with doses ranging from 0.5 to 4% DCP and 25 to 200 kGy, respectively. The effect of cross-linking on the crystalline morphology was analyzed by differential scanning calorimetry (DSC). Slight alterations in the crystalline structure were found, which were more severe in the case of peroxi modification. Through infrared spectroscopy (FTIR analysis), oxidation during the cross-linking process was detected on the DCP cross-linked samples, while b-irradiated samples do not exhibited significant degrees of oxidation. The state of cure was studied following the changes in the rheological properties in small-amplitude oscillatory shear mode, and the evolution of the molecular weight and molecular weight distribution through size exclusion chromatography. Irradiation doses below 200 kGy increased the molecular weight and branching of both copolymers but were not sufficient to reach gelation. All the peroxide modified samples resulted in a post-gel condition. Optimal mechanical properties were obtained with concentration of about 1% DCP. At higher doses, scission reactions diminish the tensile strength and the elongation at break. When polymers with equivalent amounts of gel fraction obtained by the two modification procedures studied in this work are compared, higher tensile strength and elongation at break are obtained with irradiation.
机译：两种共聚单体含量不同的茂金属乙烯-1-辛烯共聚物分别通过过氧化二枯基（DCP）或b射线辐照交联，剂量分别为0.5％至4％DCP和25至200 kGy。通过差示扫描量热法（DSC）分析了交联对晶体形态的影响。发现晶体结构有轻微改变，在过氧化物修饰的情况下更严重。通过红外光谱（FTIR分析），在DCP交联样品上检测到交联过程中的氧化，而b射线辐照的样品未显示出明显的氧化度。通过小幅度振荡剪切模式下的流变性质变化以及通过尺寸排阻色谱法改变分子量和分子量分布，研究了固化状态。低于200 kGy的辐照剂量会增加两种共聚物的分子量和支化度，但不足以达到凝胶化。所有过氧化物改性的样品均导致后凝胶状态。浓度约为1％DCP时可获得最佳的机械性能。在较高剂量下，断裂反应会降低拉伸强度和断裂伸长率。当比较通过这项工作中研究的两种改性程序获得的具有等量凝胶分数的聚合物时，通过辐照可以获得更高的拉伸强度和断裂伸长率。

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