Crystallization of Polyethylene from Xylene Solutions under High Pressure
Linear polyethylene has been isothermally crystallized from xylene solutions of various concentrations under high pressure up to 8,000 Kg/cm2. The degree of supercooling (ΔT = 10°C) and the crystallization temperature were kept constant. The differential scanning calorimetry and the electron microscopy of the crystallized polyethylene revealed that the formation of extended chain crystals (ECC) were decreased according to the increase of the xylene concentration. The characteristic peak of the differential scanning calorimeter (D S C) for ECC disappeared at the vicinity of 70% of polyethylene in xylene solution. On the other hand the size of the crystals in the direction perpendicular to its lamellar thickness grew as extremely large as more than 100μ.
KeywordsIsothermal Crystallization Crystallization Pressure High Pressure Cylinder Linear Polyethylene Viscosity Average Molecular Weight
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