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Studies of some peculiar effects of temperature on molten high‐density polyethylene properties
Author(s) -
Tanaka Koichi,
Takakura Makoto,
Koshino Yuji
Publication year - 1974
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1974.070180413
Subject(s) - high density polyethylene , materials science , viscosity , polyethylene , extrusion , shear rate , thermodynamics , melting temperature , composite material , melt flow index , polymer , copolymer , physics
Many HDPE samples show peculiar behavior of melt viscosity at low shear rate and melt strength at constant extrusion rate in a temperature region of about 200° to 250°C. It was found that the degree of the peculiarity of the behavior was affected by temperature, residence time at a temperature, the temperature rise rate, and the kind and quantities of additives. It was concluded that the peculiar effects were due to the crosslinking that a chemical reaction produced. An attempt was made to express the different behaviors of temperature dependence of melt viscosity among many HDPE samples by some simplified equations. It is suggested that both the peculiar changes with temperature of the melt viscosity and those of the melt strength may be produced by the same mechanism. The similarity of the phenomena between HDPE samples exposed to high temperatures and those crosslinked by γ‐rays was found. Finally, a possibility is discussed of predicting the processability of the resin and properties of final products before the processing operation.