Department of Polymer Science and Engineering, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, PR China.
ACS Appl Mater Interfaces. 2013 Jun 26;5(12):5550-6. doi: 10.1021/am400769j. Epub 2013 Jun 7.
In this paper, the triple shape memory effects (SMEs) observed in chemically cross-linked polyethylene (PE)/polypropylene (PP) blends with cocontinuous architecture are systematically investigated. The cocontinuous window of typical immiscible PE/PP blends is the volume fraction of PE (v(PE)) of ca. 30-70 vol %. This architecture can be stabilized by chemical cross-linking. Different initiators, 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane (DHBP), dicumylperoxide (DCP) coupled with divinylbenzene (DVB) (DCP-DVB), and their mixture (DHBP/DCP-DVB), are used for the cross-linking. According to the differential scanning calorimetry (DSC) measurements and gel fraction calculations, DHBP produces the best cross-linking and DCP-DVB the worst, and the mixture, DHBP/DCP-DVB, is in between. The chemical cross-linking causes lower melting temperature (Tm) and smaller melting enthalpy (ΔHm). The prepared triple shape memory polymers (SMPs) by cocontinuous immiscible PE/PP blends with v(PE) of 50 vol % show pronounced triple SMEs in the dynamic mechanical thermal analysis (DMTA) and visual observation. This new strategy of chemically cross-linked immiscible blends with cocontinuous architecture can be used to design and prepare new SMPs with triple SMEs.
本文系统研究了具有共连续结构的化学交联聚乙烯（PE）/聚丙烯（PP）共混物中观察到的三重形状记忆效应（SMEs）。典型的不相容 PE/PP 共混物的共连续窗口是 PE 的体积分数（v(PE)）约为 30-70 体积%。这种结构可以通过化学交联来稳定。不同的引发剂，2,5-二甲基-2,5-双（叔丁基过氧）己烷（DHBP）、过氧化二异丙苯（DCP）与二乙烯基苯（DVB）（DCP-DVB）偶联，以及它们的混合物（DHBP/DCP-DVB），用于交联。根据差示扫描量热法（DSC）测量和凝胶分数计算，DHBP 产生的交联效果最好，DCP-DVB 最差，混合物 DHBP/DCP-DVB 则介于两者之间。化学交联导致较低的熔融温度（Tm）和较小的熔融焓（ΔHm）。通过具有 50 体积%PE 的共连续不相容 PE/PP 共混物制备的三重形状记忆聚合物（SMPs）在动态力学热分析（DMTA）和目视观察中表现出明显的三重 SMEs。这种具有共连续结构的化学交联不相容共混物的新策略可用于设计和制备具有三重 SMEs 的新型 SMPs。
