ISSN:
0032-3888
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Attempts to operate plastic processing equipment at higher production rates is often accompanied by erratic flow behavior of the polymer melts. In order to study this problem, a constant-rate, capillary rheometer was used to study the melt flow over a wide range of shear rates. These data demonstrate that many high-density polyethylenes exhibit a discontinuous shear-stress shear-rate curve; that is, under certain conditions the observed load oscillates “between two values differing by about 15%”. This region of unstable melt flow is not necessarily allied with melt fracture although it is dependent on molecular weight and melt temperature. Unstable melt flow occurs at lower shear rates with a decrease in the melt index (increase in molecular weight) or melt temperature.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pen.760030106
