Formation of Interlinked Shish-Kebabs in Injection-Molded Polyethylene under the Coexistence of Lightly Cross-Linked Chain Network and Oscillation Shear Flow
Formation of Interlinked Shish-Kebabs in Injection-Molded Polyethylene under the Coexistence of Lightly Cross-Linked Chain Network and Oscillation Shear Flow
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DOI：
10.1021/ma300974w
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发表时间：
2012-08
期刊：
影响因子：
5.5
通讯作者：
Haoqing Yang;J. Lei;Liangbin Li;Q. Fu;Zhong‐Ming Li
中科院分区：
文献类型：
--
作者：
Haoqing Yang;J. Lei;Liangbin Li;Q. Fu;Zhong‐Ming Li
已经确定的是，缠结的分子网络有助于在流场下形成shish-kebab，然而，通常由长链形成的缠结网络由于分子松弛而趋于解缠结。在短链聚乙烯中加入少量的低交联聚乙烯（LCPE），将其视为稳定的分子链网络，然后采用一种改进的注射成型技术--振荡剪切注射成型（OSIM），在保压阶段对模腔中的熔体施加连续的剪切场。通过差示扫描量热仪（DSC）、广角X射线衍射仪（WAXD）和扫描电子显微镜（SEM）对OSIM样品的分级结构进行了表征。结果表明，振荡流场促进了OSIM样品中间层中相互连接的串晶的形成，而在OSIM样品的芯层中仍有典型的球晶存在。
It has been well established that the entangled molecular network facilitates the formation of shish-kebabs under flow field, however, the entangled network, usually formed by long chains, tends to disentangle due to molecular relaxation. In the present work, a small amount of lightly cross-linked polyethylene (LCPE), which can be considered as stable molecular chain networks, was added to short-chain polyethylene and then injection-molded using a modified injection molding technology-oscillation shear injection molding (OSIM), which can exert a successive shear field on the melt in the mold cavity during packing stage. The hierarchic structure of the OSIM samples was characterized through differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and scanning electron microscopy (SEM). It was found that the oscillation flow field promoted the formation of interlinked shish-kebabs in the intermediate layer of OSIM samples, while there are still typical spherulites in the core layer of OS...