title: Triple shape memory effects of cross-linked polyethylene/polypropylene blends with cocontinuous architecture.
abstract: 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.
authors.affiliation: Department of Polymer Science and Engineering, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhao
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Wang
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zhao
authors.forename: Zhenwen
authors.initials: Z
authors.lastname: Wang
authors.forename: Zhi-Min
authors.initials: ZM
authors.lastname: Dang
authors.forename: Lan
authors.initials: L
authors.lastname: Ma
authors.forename: Guo-Hua
authors.initials: GH
authors.lastname: Hu
authors.forename: Fenghua
authors.initials: F
authors.lastname: Chen
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry; D006358:Hot Temperature; D008422:Materials Testing; D011090:Polyenes / Q000737:chemistry*; D011126:Polypropylenes / Q000737:chemistry*; D013997:Time Factors
chemical_list: D003432:Cross-Linking Reagents; D011090:Polyenes; D011126:Polypropylenes; C035051:PL 732