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Crystallization of polypropylene near the surface in injection‐molded plaques: A comparison of morphology and a numerical analysis
Author(s) -
Kobayashi Yutaka,
Otsuki Yasuhiko,
Kanno Hiroaki,
Sasakawa Tomoyoshi,
Hanamoto Yasuhiro,
Kanai Toshitaka
Publication year - 2011
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.21864
Subject(s) - materials science , crystallization , crystallinity , polypropylene , morphology (biology) , crystal (programming language) , composite material , nucleation , viscoelasticity , volumetric flow rate , deformation (meteorology) , tacticity , diffraction , flow (mathematics) , chemical engineering , optics , polymerization , polymer , thermodynamics , mechanics , physics , biology , computer science , engineering , genetics , programming language
Skin morphology formation on injection‐molded isotactic polypropylene (PP) was investigated using micro‐beam synchrotron wide‐angle X‐ray diffraction and numerical simulation. The 1–20 μm depth range was characterized with an X‐ray beam of 0.273 μm χ 0.389 μm in size. From an evaluation of doping nucleating agents (NA) in PP, the NAs did not work at a depth of 1 μm. α‐specified NA affected crystallization within a 5‐μm depth. β‐specified PP showed α‐form crystallinity at the 5–20 μm depth. The mesomorphic crystal near the surface showed extremely high orientation. From viscoelastic flow simulation, PP molecules near the surface were oriented in the flow direction by extensional flow in the flow front, but freezing occurred faster than flow‐induced crystallization. It was estimated that the delay of crystallization occurred during the transient temperature. The deformation rate did not cause a difference in crystal morphology near the surface, but the cooling rate did. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers.