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Calcium stearate–stearic acid as lubricants for rigid poly(vinyl chloride) (PVC). Capillary rheometer measurements and extrusion properties
Author(s) -
Fredriksen Odd
Publication year - 1969
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.1969.070130108
Subject(s) - calcium stearate , stearic acid , extrusion , stearate , rheometer , materials science , shear rate , lubricant , chemical engineering , composite material , viscosity , rheology , calcium , magnesium stearate , polymer chemistry , chemistry , chromatography , organic chemistry , metallurgy , raw material , dosage form , engineering
Capillary rheometer measurements show that stearic acid can be characterized as a normal lubricant. If the content of stearic acid is increased in rigid PVC formulations, the melt viscosity will decrease. This leads to a corresponding increase of shear rate and volumetric flow rate. The influence of calcium stearate is opposite to the normal characteristic of a lubricant. Increasing amounts of calcium stearate lead to an increased melt viscosity and a decreased shear rate and volumetric flow rate. In the extrusion of rigid PVC, the apparent “lubricating” effect of calcium stearate is probably due to the increased friction with resulting heat evolution and higher mass temperature, leading to a decreased viscosity of the plastic melt. This is in agreement with the results of the extrusion experiments. Both mass temperature and power consumption decrease when stearic acid is added and increase when calcium stearate is added to the formulation.