POLYMER RHEOLOGY (PR) — DU B.Sc. Polymer Science Previous Year Question Papers

Attempt Five questions in all. Draw neat and labelled diagram wherever necessary. (a) Describe the phenomenon of wall slip in polymer flow. (b) How does Ellis model help in finding out the rheological behaviour of polymer and rubber melts? (c) Explain the Bagley's correction factor. How it can be used to correct the apparent shear stress to give true value of shear stress? (a) Compare low and high compression ratio screws with examples. (b) How does polymer architecture (linear vs. branched) affect rheology? (c) Compare the three types of flow (drag, pressure and leakage) in extrusion. (a) In Static Creep test for the Voigt-Kelvin Model, derive the creep behaviour and draw creep response of the model. Explain the variation of this curve with suitable mathematical relations. (b) Describe the frequency dependence of polymer viscoelastic properties (G', G", tan 8). (c) Derive the relation for dynamic modulus and dynamic viscosity for viscoelastic fluid behaviours. (3 × 5) (a) Derive the rheological relationship for Brookfield viscometer. (b) Explain the steps involved in rubber-filler mixing. (c) Describe the creep compliance function for a viscoelastic polymer. 6. Write short note on any five: (a) Stress relaxation (b) viscoelastic recovery (c) Laminar flow (d) Retardation time, 4; (e) Melt flow index (1) Bambooing defect in extrusion