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:
When a thermoplastic shape is extruded and drawn into a quenching medium and the drawing speed increases continuously, the cross-sectional extrudate area decreases. At a critical take-up speed, a cyclic gauge pulsation begins, becoming more pronounced with increasing drawing speed until the extrudate eventually breaks at the air-coolant in terface. This phenomenon, “draw resonance,” originates in the air gap and is independent of any melt fracture phenomena. Correlations show increasing pulsation severity with increases in speed ratio, air gap, viscosity-average molecular weight, and decreasing melt temperatures. Draw resonance occurs with polypropylene and various types of polyethylene and polystyrene. Ribbon-type and round-hole dies give equivalent results. A semi-quantitative theory is advanced is explain these phenomena in terms of thermodynamic relationships and basic molecular properties.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pen.760060109
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