GATE 2016 Paper with Answer Keys for Polymer Science & Engineering (XE–F)

F : Polymer Science and Engineering

Q. 1 – Q. 9 carry one mark each.

Q.1 The polymer with minimum number of branches is

(A) HDPE

(B) VLDPE

(C) LDPE

(D) LLDPE

Ans: (A) HDPE

Q.2 Nitrile rubber is a copolymer of

(A) isoprene and acrylonitrile

(B) butadiene and acrylonitrile

(C) cyclopentadiene and acrylonitrile

(D) isobutylene and acrylonitrile

Ans: (B) butadiene and acrylonitrile

Q.3 The functionality of 1,4-divinylbenzene in reactions involving addition across carbon-carbon double bond is

(A) 1

(B) 2

(C) 3

(D) 4

Ans: (D) 4

Q.4 The comonomer common to Nylon 66 and Nylon 46 is

(A) hexamethylene diamine

(B) butylene diamine

(C) adipic acid

(D) octane dicarboxylic acid

Ans: (C) adipic acid

Q.5 Polyethylene and polypropylene form an immiscible blend mainly due to

(A) entropy factor

(B) enthalpy factor

(C) crystallinity

(D) solubility

Ans: (A) entropy factor

Q.6 Rubber modulus is

(A) ratio of stress to strain

(B) same as Young’s modulus

(C) stress at specified strain

(D) stress at break

Ans: (C) stress at specified strain

Q.7 The solubility parameter is determined by using

(A) Bragg’s equation

(B) Fox equation

(C) Hildebrand equation

(D) Carother’s equation

Ans: (C) Hildebrand equation

Q.8 ‘Roller die’ consists of a combination of

(A) a two-roll calender with internal mixer feeding

(B) a two-roll calender with open mill feeding

(C) a three-roll vertical calender with two-roll mixer feeding

(D) a two-roll calender with extruder feeding

Ans: (D) a two-roll calender with extruder feeding

Q.9 Resole is an example of

(A) thermoplastic polymer

(B) thermosetting polymer

(C) natural polymer

(D) thermoplastic elastomer

Ans: (B) thermosetting polymer

Q. 10 – Q. 22 carry two marks each.

Q.10 Match the processing technique to the appropriate product listed below:

Processing Technique	Product
P. Blow molding	1. Bucket
Q. Co-extrusion	2. Blister packaging
R. Injection molding	3. Bottles
S. Thermoforming	4. Multilayered sheets

(A) P-3; Q-4; R-2; S-1

(B) P-3; Q-1; R-4; S-2

(C) P-3; Q-4; R-1; S-2

(D) P-3; Q-2; R-1; S-4

Ans: (C) P-3; Q-4; R-1; S-2

Q.11 For a high molecular weight polymer sample with a viscosity of 6 x 10¹¹ Poise and a stressrelaxation modulus of 3 x 10⁶ dyne cm^-2 at a given temperature, the relaxation time will be _____hours.

Ans: 55.0 : 56.0

Q.12 Match the following polymer additives to their function:

Additive	Function
P. Azocarbonamide	1. Chemical plasticizer
Q. Antimony trioxide	2. Accelerator
R. Pentachlorothiophenol	3. Flame retardant
S. Mercaptobenzothiazole	4. Blowing agent

(A) P-4; Q-1; R-3; S-2

(B) P-4; Q-2; R-1; S-3

(C) P-4; Q-3; R-2; S-1

(D) P-4; Q-3; R-1; S-2

Ans: (D) P-4; Q-3; R-1; S-2

Q.13 Tensile force of 165 N is applied to a piece of vulcanized rubber of dimension 4 mm x 4 mm x 30mm. If the sample is elongated by 50% of its original length under the same applied force, the true stress will be _ MPa.

Ans: 15.42 : 15.52

Q.14 The order of glass transition temperature for the given polymers is [NR=natural rubber; PP=polypropylene; PE=polyethylene; PMMA=poly(methyl methacrylate)]

(A) NR < PE < PP < PMMA

(B) PE < NR < PP < PMMA

(C) PE < PP < NR < PMMA

(D) NR < PP < PE < PMMA

Ans: (B) PE < NR < PP < PMMA

Q.15 Dynamic mechanical analysis of polystyrene (T_g = 100 ºC) measured at a frequency of 1 Hz shows the damping peak at 110 ºC. If the measurement is made at 10⁴ Hz, then the peak temperature (ºC) will be

(A) 123.2

(B) 133.2

(C) 143.2

(D) 153.2

Ans: (B) 133.2

Q.16 Match the product to the most suitable plastic listed below:

Product	Plastic
P. Baby feeding bottle	1. Polypropylene
Q. Tiffin box	2. Poly(ethylene terephthalate)
R. Water bottle	3. Poly(vinyl chloride)
S. Blood bag	4. Polycarbonate

(A) P-1; Q-4; R-2; S-3

(B) P-4; Q-1; R-2; S-3

(C) P-1; Q-3; R-2; S-4

(D) P-4; Q-3; R-2; S-1

Ans: (B) P-4; Q-1; R-2; S-3

Q.17 The number average molecular weight for the polymerization of adipic acid and ethylene glycol (feed ratio 1:1) at 99 percent conversion is __ g mol^-1.

Ans: 8590 : 8610

Q.18 A composite material contains 30 % by volume of uniaxially aligned glass fibres in a matrix of alkyd resin. The tensile moduli of the glass fibre and alkyd resin are 76 GPa and 3 GPa, respectively. If a tensile stress of 100 MPa is applied parallel to the fibres, the percentage
longitudinal strain is _ .

Ans: 0.35 : 0.45

Q.19 Match the elastomers listed below to the appropriate curing agent:

Elastomer	Curing Agent
P. Silicone rubber	1. Zinc oxide + ethylene thiourea
Q. Natural rubber	2. Diamine
R. Chloroprene rubber	3. Sulfur
S. Acrylate elastomer	4. Dicumyl peroxide

(A) P-4; Q-3; R-1; S-2

(B) P-3; Q-4; R-1; S-2

(C) P-4; Q-1; R-3; S-2

(D) P-2; Q-3; R-4; S-1

Ans: (A) P-4; Q-3; R-1; S-2

Q.20 The weight of graphite fiber (density = 1800 kg m^-3) that should be added to 1.00 kg of vinyl ester resin (density = 1250 kg m^-3) to produce a composite with a density of 1600 kg m^-3 is _ kg.

Ans: 2.3 : 2.7

Q.21 If the values of K and a in the Mark-Houwink equation are 1.5 x 10^-4 dL g^-1 and 0.60, respectively, the viscosity average molecular weight of a polymer having an intrinsic viscosity of 0.05 dL g^-1 is _ kg mol^-1.

Ans: 15.5 : 16.5

Q.22 A rectangular polymer bar of length 40 mm fits exactly into a steel mold cavity and the entire assembly was heated from 20 to 100 ºC. The linear thermal expansion coefficients of the polymer and steel are 80 x 10^-6 ºC^-1 and 11 x 10^-6 ºC^-1, respectively. The strain encountered by the polymer sample along the length will be _ %.

Ans: 5.4 : 5.6

END OF THE QUESTION PAPER