April 15, 2000

Diagnostic Quiz in Polymer Processing Basics

Perspective Meter:

1. A Newtonian liquid is subject to drag flow between parallel plates. The upper plate moves with velocity V while the lower plate is stationary. illustrate: a) the velocity profile and b) the shear rate profile in the flow as functions of the coordinate y normal to the direction of flow.

2. Write the continuity equation. What basic principle does this equation represent?

3. In a stress relaxation experiment, a cylinder of material is instantaneously stretched from length Lo to length Lf and held at Lf. Sketch qualitatively the tensile stress as a function of time which is required to maintain this deformation for a) an elastic solid; b) a viscoelastic solid; and c) a Newtonian liquid.

4. Give one specific example of a chain-growth polymerization reaction.

5. Sketch the tensile modulus as a function of temperature for a typical non-crystallizable thermoplastic polymer. Identify particular regions of interest on the curve.

6. Velocities u and v in a flow in the x-y plane are governed by the following pair of partial differential equations:
From the flow symmetry it is known that v is a function of x only. The boundary conditions are as follows:
What are the velocities v(x) and u(x,y)?
7. A long, narrow slab of hot amorphous polymer of width W at temperature Ti is quenched into a large water bath at Twater at time=0. Sketch how you would expect the temperature distribution within the slab to vary as a function of time and distance x from the centerline of the slab.

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