The document discusses key concepts in polymer structure-property relationships including: 1. Classifying polymers based on source, structure, and stereoregularity, and distinguishing between copolymers and polymer blends. 2. Differentiating polymerization reactions based on stoichiometry and mechanism, and comparing step and chain polymerization. 3. Explaining mechanical properties of polymers like stress, modulus of elasticity, and toughness, and classifying non-Newtonian fluids. 4. Discussing polymer transitions temperatures including glass transition temperature, and using differential scanning calorimetry to analyze transitions.

1. 2009 – 10
B.Tech. (VII semester) Examination
(Open Elective – II)
POLYMER STRUCTURE PROPERTY RELATIONSHIP
(PK – 428-D)
Credits: 04
Maximum Marks: 60
Duration: Three Hours
1(a) Classify the polymers on the basis of (a). Source, (b). Structure, (c). Stereo 05
regularity.
Or
(a’) What is the difference between copolymers and polymer blends? Explain 05
types of copolymers with suitable examples.
(b) Differentiate the polymerization reaction on the basis of (a). Stoichiometry 05
and (b). Mechanism. Give suitable examples.
(c) What is the difference between step and chain polymerization? Compare the 05
growth of molecular weight with % conversion in step and chain
polymerization.
2(a). What do you mean by mechanical properties of polymers? Explain the 05
following terms with their units in MKS system.
(a). True stress, (b). Modulus of Elasticity, (c). Tensile strength at break,
(d). Toughness
Or
(a’). Why polymers are known as viscoelastic materials? Explain the Thermo- 05
mechanical curve for polymeric materials.
(b). Classify the non-Newtonian fluids with example. What the difference is 05
between shear strain and shear strain rate? Give the shear rate range for
various polymer processing methods.
(c). What do you mean by Rheological Models? Explain the difference between 05
Power Law Model and Truncated Power Law Model in light of shear rate
range in viscometeric plot.
Or
(c’). Explain the phenomenon of Stress relaxation and Creep in viscoelastic 05
materials.
3(a). Explain the response of a Hookean Solid, Newtonian Fluid and a 05
Viscoelastic polymer to sinusoidal load with the help of stress – strain plot.
Differentiate between storage modulus and loss modulus.
Or

2. (a’). What do you mean by transition temperatures in polymers? Other than glass 05
transition temperature explain any other transition temperature. Briefly
explain the factors affecting glass transition temperature.
(b). Explain the construction and working of Differential Scanning Calorimeter 05
(DSC). Explain how you will relate the DSC curve with glass transition
temperature, crystallization, melting and degradation of polymer.
(c). What do you mean by solubility parameter of a polymer, what is its unit? 05
What are the conditions of two or more polymer forming a miscible or
immiscible blend?
4(a). What do you mean by polarization? Explain the types of polarization in a 05
dielectric (polymer). Explain the type of polarization a non polar polymer will
undergo and why?
Or
(a’). Explain the various electrical properties required from a polymer insulation 05
containing a high voltage – high frequency electrical wire.
(b). Give the expression for electrical field acting on an atom/ molecule. Explain 05
the phenomenon of and how electrical relaxation time it depends upon the
radius of molecule and viscosity of system according to Debye?
(c). What will happen to a dielectric (polymer) subjected to a varying electrical 05
field? Differentiate between dielectric dissipation factor (tanδ) and
dielectric loss factor (ε’’).
Or
(c’) Explain the dependency of dielectric constant (ε) on internal viscosity of 05
polymer, temperature, frequency and presence of dipole in polymer
structure.