Uttar Pradesh Technical University (UPTU) 2006 B.Tech Chemical Engineering STRUCTURE, PROPERTY & CHARACTERIZATION OF POLYMERS - Question Paper

Time : three Hours [Total Marks : 100
Note: Attempt all ques..

1 Attempt any 2 ques. Marks[10x2]

(a) Highlight a few physical and thermal properties of PVC and HDPE with special reference to their structure.

(b) Why do we consider avg. molecular weight for polymers? provide various kinds of avg. molecular weight for polymers.

(c) Write short notes on any 2 of the subsequent with the help of example(s).
(1) Intermolecular forces
(2) Chemical Stability
(3) Chain - extending bond.

2 Attempt any 4 of the subsequent : Marks[5x4]

(a) explain the method of end - group analysis for determining number avg. molecular weight. A sample (3.0 gm) of carboxyl-terminated polybutadiene (CTPB) needed titration with 20 ml 0.1N-KOH solution to reach a phenolphthalein end point. compute number - avg. molecular weight of the polymer sample.

(b) What do you understand by solution viscosity? provide various kinds of viscosity terms used for solution viscosity. Also, provide the significance of the subsequent relation:
ri= ri=l + 2.5<|>, where the terms are
of their usual meanings.

(c) Write down the merits and demerits of measuring the molecular weights based on colligative properties.

(d) How does the crystallinity affect mechanical properties of polymers? explain this.

(e) explain linear, branched and crosslinked polymers in terms of their basic properties.

3 Attempt any 2 of the subsequent : Marks[10x2]

(a) define the Zimm's method for the determination of molecular weight of polymers with the help of Light - scattering phenomenon.

(b) define Gel Permeation Chromatographic (GPC) technique for the determination of molecular weights and molecular weight distribution curve for polymers.

(c) What is solubility parameter? explain various methods for determining solubility parameter.

4 Attempt any 2 of the subsequent : Marks[10x2]

(a) define the melting behaviour of polymers. How can it be correlated with the structure of polymers? discuss with examples.

(b) What do you understand by glass-transition temperature (Tg) of polymers? discuss its significance at molecular level. Also describe, with examples, the different structural factors which affect the Tg.

(c) Discuss, in detail, the experimental procedure for the determination of Tg and Tm by differential scanning calorimetry (DSC).

5 Attempt any 2 of the subsequent : Marks[10x2]

(a) What do you understand by copolymerization technique? elaborate the different properties affected due to change in the structure of comonomer of the copolymer? explain with the help of suitable example.

(b) explain the principle of Scanning Electron Microscopic (SEM) analysis. provide the instrumental details and procedure for analyzing polymer samples by SEM.

(c) elaborate the different requirements for the polymers to be crystalline? define the Fringed Micelle and Folded - chain crystallites models for the polymers.


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