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Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by π-π Stacking Interactions
Published on: October 10, 2016
Oriented Gamma Phase in Isotactic Polypropylene Homopolymer
Tim B van Erp1, Luigi Balzano2, Gerrit W M Peters1
1Department of Mechanical Engineering, Materials Technology Institute, Eindhoven University of Technology, P.O.Box 513, 5600 MB, Eindhoven, The Netherlands.
Abstract:
The presence of γ-phase in isotactic polypropylene is well-known but, up until now, could only be induced by specific processing conditions or material modifications. Typically, for Ziegler-Natta (ZN) iPPs pressures of 2000 bar are required, otherwise, metallocene (M) iPPs and copolymerization using olefin-type counits should be used. Here we show that crystallization under the unique combination of moderate pressure (p ≥ 900 bar) and strong shear flow oriented specimens with high contents of γ-phase are created in ZN-iPPs. The oriented morphology is qualified as a shish-kebab structure that templates densely branched γ-lamellae on parent α-lamellae as well as directly to the shish backbone.
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