Document Type

Thesis

Date of Award

1-31-1967

Degree Name

Master of Science in Chemical Engineering - (M.S.)

Department

Chemical Engineering

First Advisor

Saul I. Kreps

Second Advisor

C. L. Mantell

Third Advisor

William H. Snyder

Abstract

A procedure was developed to convert shear stress at various melt temperatures into a computed shear stress at a constant temperature in an isothermal system.

The isothermal shear stress was first analyzed at an equilibrium condition before time induced stress reduction for

1) the temperature dependency of shear stress

2) non-newtonian flow behavior

3) a relationship between the independent variables of shear rate, filler concentration and temperature, and shear stress.

A statistical analysis was performed on the data to find an empirical relationship between shear stress and the independent variables, at any time, under stress, for unfilled and filled high density polyethylene.

Calculation of the flow behavior index indicated 1) as the polymer concentration is decreased in the polymer-filler melt, the behavior is increasingly non-ideal. 2) the flow behavior index of a filler-polymer melt decreases with increase in temperature, whereas the flow behavior index forvirgin polyethylene increases with temperature.

Second order equations relating all variables to shear stress explains 84 to 97% of the variability of shear stress and the contribution: of each variable to shear stress.

Time does not significantly change the effect of temperature, the largest contributor to reduction in shear stress.

A procedure has been developed, to predict the shear stress of more than one molecular weight high density virgin polyethylene.

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