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Extrusion of broad‐molecular‐weight‐distribution polyethylenes
Author(s) -
Krishnaswamy Rajendra K.,
Rohlfing David C.,
Sukhadia Ashish M.,
Slusarz Kevin R.
Publication year - 2004
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.20254
Subject(s) - extrusion , materials science , rheology , polyethylene , shear thinning , polymer , molar mass distribution , shear rate , composite material , polymer science
Abstract The extrusion (single‐screw) characteristics of four high‐molecular‐weight, broad‐molecular‐weight‐distribution (MWD) polyethylene resins are discussed with an emphasis on the output rate. Despite the high molecular weights of the subject polyethylenes, their broad MWD ( M w / M n range: 10 to 50) does not limit the pressure and torque developed during extrusion. However, the specific output of the four polymers was quite varied. First, the dynamics of the solids conveying section were examined with the highest‐molecular‐weight polyethylene exhibiting lower solids‐conveying rate than the other three. Further, a simple and quick method to evaluate the relative solids‐conveying efficiencies for various polyethylenes is presented. Finally, the dependence of the specific output on the melt rheology of the polymers is also addressed; specifically, the shear‐thinning extent of the melt in the metering section was found to influence output rate. The unique and counterintuitive temperature‐dependence of the shear‐thinning character for one of the four polymers will also be addressed in relation to its extrusion characteristics. Polym. Eng. Sci. 44:2266–2273, 2004. © 2004 Society of Plastics Engineers.