Engineering Sciences
GATE XE Chemistry of high polymers PYQs
Build your understanding with focused practice from past exam papers.
Questions 31–40 of 66. Imported answers require independent review unless marked reviewed.
Question 131
Open questionXE-FNAT2 marksNeeds review
The enthalpy of fusion for a polymer is found to decrease from 135.6 J g
to 120 J g
after five years of use. If the enthalpy of fusion of the same polymer with 100% crystallinity is 290 J g
, then the loss in crystallinity after five years is ______ % (rounded off to one decimal place).Log in to check the answer
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Linear low density polyethylene (LLDPE) is a copolymer of ethylene and a small fraction of ________.
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Polymer crystals show a range of melting points in contrast to single melting point of crystals of small molecules, because ________.
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When the rate of cooling is increased during the solidification process, the glass transition temperature of a polymer ________.
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There are two different PTFE polymer specimens of the following density (
) and % crystallinity. For PTFE- specimen-1,
is 2.144 g/cm³ and % crystallinity is 50. For PTFE- specimen-2,
is 2.215 g/cm³ and % crystallinity is 75. Assuming the polymer is pure and defect free, the density (rounded off to 3 decimal places) of 100% amorphous PTFE specimen will be ______ g/cm³.Log in to check the answer
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A particular free radical polymerization process yields a polymer with a number average degree of polymerization,
= 100. The monomer concentration is doubled and the initiator concentration is increased by four times. Assuming that all rate coefficients and other parameters remain unchanged, the value of
(rounded off to the nearest integer) is ______.Log in to check the answer
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A polymer is synthesized from 2 moles of terephthalic acid (molecular weight of the repeat unit, (-OCC₆H₄CO-), is 132 g/mol), 1 mol of ethylene glycol (molecular weight of the repeat unit, (-OCH₂CH₂O-), is 60 g/mol), and 1 mol of butylene glycol (molecular weight of the repeat unit, (-O(CH₂)₄O-), is 88 g/mol). The reaction is terminated at 99% conversion of the acid. The number averaged molecular weight,
(rounded off to the nearest integer) is ______ g/mol.Log in to check the answer
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The solvent in which chain transfer is maximum in a radical polymerization is
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The monomer that can NOT be polymerized by anionic polymerization is
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Open questionXE-FMCQ2 marksNeeds review
Match the polymers in Column A with their corresponding polymerization methods in Column B.
Column A | Column B |
|---|---|
P — Bisphenol A polycarbonate | 1 — Cationic |
Q — Polyethylene | 2 — Step-growth |
R — Poly(styrene-b-butadiene) | 3 — Coordination |
S — Butyl rubber | 4 — Anionic |
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