Extrusion, Spinning and Coating - Polymer Processing - Engineering Sciences Previous Year Questions

1

2008 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2008

The capacity of an extruder can be maximized by a combination of

A

higher barrel diameter; higher screw diameter; higher helix angle; higher rpm

B

higher barrel diameter; higher screw diameter; higher helix angle; lower rpm

C

higher barrel diameter; higher screw diameter; lower helix angle; higher rpm

D

higher barrel diameter; lower screw diameter; higher helix angle; higher rpm

Open complete paper

2

2009 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2009

The power consumed by the plasticizing screw is

A

5 kW

B

1 kW

C

2.5 kW

D

10 kW

Open complete paper

3

2011 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2011

Assume a flat plate model in the melt zone of a single-screw extruder \(\partial P/\partial z = \eta \partial^2 v_z/\partial y^2\), \(v_z = 0\) at \(y = 0\) and \(v_z = V_{bz}\) at \(y = H\). For fully developed flow in the z direction \(v_z\) is found to be

A

\(v_z = V_{bz} (y/H) - [y (H-y) \partial P/\partial z]/(2\eta)\)

B

\(v_z = (y/H) + [y (H-y) \partial P/\partial z]/(2\eta)\)

C

\(v_z = (y^2/H) + [y (H-y) \partial P/\partial z]/(2\eta)\)

D

\(v_z = (y^2/H) - [y (H-y) \partial P/\partial z]/(2\eta)\)

Open complete paper

4

2011 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2011

In the absence of a die in a single screw extruder \(\Delta P = 0\) and Q is equal to

A

0.31 cm³/sec

B

3.11 cm³/sec

C

311 cm³/sec

D

31.1 cm³/sec

Open complete paper

5

2013 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2013

In the extruder barrel, the compression is achieved by back pressure created by the die and by

A

increasing pitch and decreasing diameter of the screw

B

using the tapered barrel with constant pitch

C

increase in the clearance between barrel surface and screw

D

opening of the die

Open complete paper

6

2013 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2013

An extruder is supplied with 40 kW of power. The mass flow rate of a polymer through the extruder is 240 kg h^-1 and the specific heat capacity of the polymer is 4 kJ kg^-1 K^-1. The maximum possible temperature rise in the polymer is

A

150 K

B

100 K

C

600 K

D

Zero

Open complete paper

7

2014 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2014

A continuous annular product is produced by

A

compression molding

B

extrusion

C

blow molding

D

injection molding

Open complete paper

8

2014 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2014

The shear rates involved in calendering ($\dot{\gamma}_{cal}$), compression molding ($\dot{\gamma}_{comp}$), extrusion ($\dot{\gamma}_{ext}$), and injection molding ($\dot{\gamma}_{inj}$) processes follow the order

A

$\dot{\gamma}_{inj} < \dot{\gamma}_{cal} < \dot{\gamma}_{ext} < \dot{\gamma}_{comp}$

B

$\dot{\gamma}_{comp} < \dot{\gamma}_{ext} < \dot{\gamma}_{cal} < \dot{\gamma}_{inj}$

C

$\dot{\gamma}_{comp} < \dot{\gamma}_{inj} < \dot{\gamma}_{ext} < \dot{\gamma}_{cal}$

D

$\dot{\gamma}_{comp} < \dot{\gamma}_{cal} < \dot{\gamma}_{ext} < \dot{\gamma}_{inj}$

Open complete paper

9

2015 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2015

The diameter of a die of an extruder producing extrudate of diameter 2.4 mm with a die-swell ratio of 2 is ______ mm.

Check answer

Open complete paper

10

2017 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2017

Which processing technique is best suited for manufacturing decorative PVC floor tiles?

A

Blow molding

B

Filament winding

C

Rotational molding

D

Calendering

Open complete paper

11

2019 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2019

A single screw extruder is to be used to manufacture a nylon rod of 0.5 cm diameter at a production rate of 2.5 cm s⁻¹. The density of solid nylon and nylon melt are 1.140 g cm⁻³ and 0.790 g cm⁻³, respectively. The melt flow rate through the die is ______ cm³ s⁻¹ (round off to two decimal places).

Check answer

Open complete paper

12

2021 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2021

A single screw extruder is operating at a rotational speed of 2 revolutions per second for the extrusion of a Newtonian polymer under open-discharge conditions (in absence of a die, the pressure drop, Δp = 0). The extruder has a screw diameter, D = 5 cm, a channel depth, H = 0.4 cm, distance between flights, W = 1 cm, and a helix angle, θ = 20°. Assume the value of π = 3.14. The volumetric flow rate (rounded off to 2 decimal places) is __________ cm³/s.

Check answer

Open complete paper

13

2023 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2023

A high molecular weight polymer passes through different zones from the hopper to the die in an extruder. Among the options given, identify the correct match between the zones and their key functions.

A

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

B

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

C

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

D

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

Open complete paper

14

2023 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2023

A polymeric material of density 0.9 g/cc and melt volume of 10 cc in an extruder has a residence time of 100 s. The output of the extruder is _____ kg/h. (Rounded off to two decimal places)

Check answer

Open complete paper

15

2025 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2025

Choose the option(s) that correctly match(es) the Zones with their typical Functions in an industrial extruder.

Zones		Functions
P	Feed zone	1	The melt acquires a constant flow rate
Q	Compression zone	2	No heating takes place
R	Metering zone	3	Polymer melts due to heat transferred from the heating element
		4	The helical flight of the screw imparts constant flow of the melt
		5	Polymer melts due to shear forces imparted by the screw

A

P-2; Q-5; R-1

B

P-2; Q-3; R-4

C

P-5; Q-1; R-2

D

P-2; Q-1; R-3

Check answer

Open complete paper

16

2026 · Engineering Sciences · Polymer Processing · Extrusion, Spinning and Coating

Engineering Sciences (XE) 2026

A single-screw extruder is operated at 12 rpm under open discharge condition (i.e., without a die).
The screw has a diameter of 10 cm, a distance of 2.5 cm between the adjacent flights, a gap of 0.25 cm between the screw and the inner wall of the barrel, and a helix angle (i.e., angle between the flights and the plane perpendicular to the screw axis) of 8°.
If the flow of the molten polymer in the metering zone through the extruder is assumed isothermal, Newtonian and incompressible, the volumetric flow rate of the polymer melt is ______ cm³/min (rounded off to the nearest integer).

Check answer

Open complete paper