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Rheological properties of polypropylene/high‐density polyethylene blend melts. I. Capillary flow properties
Author(s) -
Fujiyama Mitsuyoshi,
Kawasaki Youtoku
Publication year - 1991
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.1991.070420219
Subject(s) - high density polyethylene , materials science , melt flow index , composite material , polypropylene , rheology , polymer blend , polyethylene , capillary action , die swell , viscosity , tacticity , plastics extrusion , polymer , polymerization , copolymer
Three kinds of isotactic polypropylenes (PP) with different melt flow indexes (MFIs) were melt‐blended with three kinds of high‐density polyethylenes (HDPE) with different MFI using a screw extruder, and the morphologies and capillary flow properties such as flow curve, entrance effect, Barus effect, and melt fracture were studied. When HDPE contents were 70 wt % or above and PP particles formed the disperse phase, the size of the particles decreased with decreasing viscosity of PP. When HDPE contents were 30 wt % or below and HDPE particles formed the disperse phase, the size of the particles was minimum when the viscosities of PP and HDPE were similar. The die swell ratios of the blends were higher than those of the components. On the other hand, the entrance correction coefficients of the blends were intermediate between those of the components. There was no correlation between the die swell ratio and the entrance corretion coefficient. Therefore, it is not always appropriate to regard the entrance correction coefficient as a measure of melt elasticity in the case of inhomogeneous polymer systems such as PP/HDPE blend.