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Hierarchical crystalline structures and dynamic mechanical properties of injection‐molded bars of HDPE: attributes of temperature field
Author(s) -
Wang Long,
Yang MingBo,
Zhang QuanPing,
Zhang RuiYan,
Wu JingJing,
Feng JianMing
Publication year - 2013
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/pat.3114
Subject(s) - materials science , differential scanning calorimetry , composite material , high density polyethylene , molding (decorative) , scanning electron microscope , temperature gradient , dynamic mechanical analysis , bar (unit) , optical microscope , cooling curve , polyethylene , polymer , thermodynamics , physics , quantum mechanics , meteorology , metallurgy
The relationship among the processing parameters, crystalline morphologies and mechanical properties of injected‐molded bar becomes much complicated primarily due to the existence of temperature gradient coupled with the shear gradient along the sample thickness. The effect of thermal gradient field on the microstructural evolution, hierarchical structures and dynamic mechanical properties of high‐density polyethylene parts molded via gas‐assisted injection molding (GAIM) were investigated using scanning electron microscope, differential scanning calorimetry, dynamic mechanical analysis and two‐dimensional wide‐angle X‐ray diffraction. The three‐dimensional temperature profiles during the cooling stage under different melt temperatures of GAIM process were obtained by using a transient heat transfer model of the enthalpy transformation approach, and the phase‐change plateaus were clearly observed in the cooling curves. It was found that a variety of melt temperatures could induce considerable variations of the hierarchical structures, orientation behavior and dynamic mechanical properties of the injection‐molded bars. With reduced melt temperature, GAIM samples with higher molecular orientation and improved dynamic mechanical properties were obtained. Copyright © 2013 John Wiley & Sons, Ltd.