GATE XE topic:polymer-rheology PYQs & Answers — Page 2

Questions 11–20 of 27. Imported answers require independent review unless marked reviewed.

Match the polymer processing operation with respect to its typical range of shear rate.

Processing Operation	Shear rate (s⁻¹)
P. Compression Moulding	1. 1000 - 10000
Q. Extrusion	2. 100 - 1000
R. Calendering	3. 1 - 10
S. Injection Moulding	4. 10 - 100

Your answerChoose one option.

P-3, Q-4, R-2, S-1

P-1, Q-3, R-2, S-4

P-2, Q-4, R-3, S-1

P-3, Q-2, R-1, S-4

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Shear stress (

) and shear viscosity (

) are plotted as functions of the shear rate,

, for idealized “solid-like with yielding (1)” and “liquid-like (2)” materials.

Diagram for Engineering Sciences question 12

Associate the shear stress and viscosity plots with the appropriate material responses.

Your answerChoose one option.

P-2, Q-1, R-2, S-1

P-1, Q-2, R-1, S-2

P-1, Q-2, R-2, S-1

P-2, Q-1, R-1, S-2

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The plateau modulus of polystyrene has a value of 0.2 × 10⁶ Pa at 150 °C. Given, the density of polystyrene is 1.05 g/cm³, the universal gas constant,

= 8.3 J K⁻¹ mol⁻¹, and the monomer molecular weight is 104 g/mol. The molecular weight between entanglements (rounded off to the nearest integer) of polystyrene chains is ______ g/mol.

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At 215 °C, the viscosity of a polystyrene of molecular weight 250 × 10³ g/mol is 8.0 × 10³ Pa s. The critical molecular weight of polystyrene,

= 35 × 10³ g/mol. For a similar polystyrene of molecular weight 500 × 10³ g/mol, the viscosity (rounded off to nearest integer) will be ______ × 10³ Pa s.

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The behavior of a polymer is described by a Maxwell model consisting of a spring element of modulus 10¹⁰ Pa in series with a dashpot of viscosity 10¹² Pa s. In the solid, 50 s after the sudden application of a fixed strain of 1%, the stress (rounded off to 2 decimal places) will be ______ × 10⁷ Pa.

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The change in stress of a polymer as a function of time at a fixed strain is known as

Your answerChoose one option.

Fatigue

Creep

Stress relaxation

Fracture toughness

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Plot of shear stress against shear rate for various types of fluids is given below. The appropriate assignment for P, Q, R and S is

Diagram for Engineering Sciences question 14

Your answerChoose one option.

P-Dilatant, Q-Bingham plastic, R-Pseudoplastic, S-Newtonian

P-Bingham plastic, Q-Pseudoplastic, R-Dilatant, S-Newtonian

P-Pseudoplastic, Q-Bingham plastic, R-Newtonian, S-Dilatant

P-Newtonian, Q-Dilatant, R-Pseudoplastic, S-Bingham plastic

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A polymer solution flows through a cylindrical tube with a diameter of 4 mm at a volumetric flow rate of 10⁻⁹ m³ s⁻¹. Under laminar flow condition and assuming the polymer solution to be a Newtonian fluid with viscosity 10² N s m⁻², the value of pressure drop per unit length of the tube in N m⁻³ is ______ (round off to nearest integer). [Consider the value of π as 3.14]

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A linear amorphous polymer has a T_g of +10 °C. At 28 °C, it has a melt viscosity of 4 × 10⁸ poise. The viscosity of the polymer at its T_g is ______ × 10¹³ poise (round off to one decimal place).

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A 3 mm thick layer of softened poly(methyl methacrylate) at 190 °C is sandwiched between two flat parallel plates. A shear stress of 100 kPa is applied to the softened polymer. Assuming the softened polymer as a Newtonian fluid with an apparent viscosity of 3.9 × 10⁴ Pa s, the relative sliding velocity between the two plates is ____ mm s⁻¹ (round off to one decimal place).

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GATE XE topic:polymer-rheology PYQs

Question 11

Question 12

Question 13

Question 16

Question 18

Question 9

Question 14

Question 19

Question 16

Question 19