Injection Molding of Liquid-Crystalline Polymer

概要

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A liquid-crystalline copolyester consisting of 1, 4-oxybenzoate and ethylene terephthalate groups was subjected to the injection molding using a rectangular mold 120×70×1mm with a slot gate of 0.5mm gap. The structures of injection-molded products were studied in detail by the X-ray diffraction method and the techniques of polarizing microscope. The molecules in the outer layers contiguous to both surfaces of injection-molded rectangular plate were highly oriented in the direction of injection and strongly birefringent, whilst the interior layer remained principally unoriented. The generation of characteristic binary structure with sharp boundaries was interpreted in terms of CAE data and the rheological behavior of the melt of liquid-crystalline polymer. The products of usual polymer made up of flexible molecules, on the contrary, gave isotropic products. The measurements of relaxation time afforded a key to an understanding of the difference between the behavior of liquid-crystalline polymer and that of usual polymer. The structural anisotropy of the products of liquid-crystalline polymer resulted in the anisotropy of mechanical properties. The structure produced by processing proved to be a determining factor for the mechanical propertties of products in preference to the material of which the product was composed.
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