The effect of die materials and pressure-dependent slip on the extrusion of linear low-density polyethylene
| Autor: | Timothy J. Person, Morton M. Denn |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
business.product_category
Mechanical Engineering Slip (materials science) Plasticity Polyethylene Condensed Matter Physics Brass Linear low-density polyethylene chemistry.chemical_compound chemistry Mechanics of Materials visual_art visual_art.visual_art_medium Die (manufacturing) General Materials Science Extrusion Slip ratio Composite material business |
| Zdroj: | Journal of Rheology. 41:249-265 |
| ISSN: | 1520-8516 0148-6055 |
| Popis: | The flow of linear low-density polyethylene through stainless-steel slit dies occurred at shear rates approximately 12% higher than in identical α-brass dies at the same wall shear stresses, indicating near-wall slip. The flow curves were independent of gap spacing. We show through the slip theory of Hill and co-workers [J. Rheol. 34, 891–918 (1990)] that a measurable gap dependence of the flow curve is not a necessary consequence of wall slip; the flow curves for both stainless steel and α-brass dies can be fit with the same rheological parameters, with a difference in the work of adhesion accounting for the differences in the flow curves. X-ray photoelectron spectroscopy revealed differences in the chemistry of brass surfaces with different pretreating, corresponding to small differences in flow curves. Fluorocarbon-coated die surfaces showed no more slip than stainless steel, while the flow curve with gold-coated surfaces followed stainless steel at intermediate stress and brass at high stress. |
| Databáze: | OpenAIRE |
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