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Polymers

Description: Polymers; Chemistry GATE IIT Polymerization Industries
Number of Questions: 20
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Tags: Polymers; Chemistry GATE IIT Polymerization Industries
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Which of the following additives are used as flame retardants for polymers?

  1. Trisethylhexy trimellitate
  2. Phthalocyanine
  3. Alumina trihydrate
  4. Octabromobiphenyl oxide
  1. Only 1 and 2

  2. Only 1 and 4

  3. Only 2 and 3

  4. Only 2 and 4

  5. Only 3 and 4


Correct Option: E
Explanation:

It is correct. Alumina trihydrate and octabromobiphenyl oxide are used as flame retardants for polymers.

Toluene behaves as a plasticiser for polystyrene. What is the Transition temperature (Tg) of a polystyrene sample containing 30 vol% toluene?

  1. 100° C

    • 100° C
    • 50° C
  2. 55° C

    • 55° C

Correct Option: D
Explanation:

Since, toluene is completely compatible with polystyrene. Tg = V1Tg1 + V2Tg2 where, Tg1, Tg2 = Glass transition temperature of polystyrene and toluene respectively. V1, V2 = Volume fraction of polystyrene and toluene respectively. Tg1 = 100° C Assuming Tg2 = Melting point of toluene = -50° C Tg = 0.70 (100) + 0.30 (-50) = 70 - 15 = 55° C

Arrange the following polymers in increasing order of their glass transition temperature (Tg) -

  1. Polypropylene
  2. Polystyrene
  3. Poly(α-methylstyrene)
  4. Poly(o-methylstyrene)
  5. Poly(m-methylstyrene)
  1. 1 < 2 < 3 < 4 < 5

  2. 1 < 3 < 2 < 5 < 4

  3. 1 < 5 < 2 < 4 < 3

  4. 2 < 1 < 4 < 5 < 3

  5. 2 < 5 < 1 < 4 < 3


Correct Option: C
Explanation:

Bulky side groups that are stiff and close to the backbone cause steric hindrance, decrease chain mobility and hence,  raise glass transition temperature (Tg).Polypropylene (Tg = –10 °C) < Poly(m-methylstyrene) (Tg = 72 °C) < Polystyrene (Tg = 100 °C) < Poly(o-methylstyrene) (Tg = 119 °C) < Poly(α-methylstyrene) (Tg = 192 °C). Hence, the correct answer is 1 < 5 < 2 < 4 < 3.

Which of the following polymers is/are formed by anionic ring opening polymerisation of caprolactum?

  1. Polyoxymethylene
  2. Poly(tetramethylene oxide)
  3. Polycaprolactam
  1. Only 1

  2. Only 2

  3. Only 3

  4. Only 1 and 2

  5. Only 2 and 3


Correct Option: C
Explanation:

Polycaprolactam is formed by hydrolytic and anionic ring opening polymerisation of caprolactam.

Calculate the Tg of butadiene–styrene copolymer containing 20 vol% styrene.

    • 44° C
  1. 44° C

    • 80° C
  2. 80° C

  3. 100° C


Correct Option: A
Explanation:

Butadiene and styrene form a completely compatible random copolymer. Therefore, the following relation is applicable: Tg = V1Tg1 + V2Tg2. Assume 1= polybutadiene 2 = polystyrene Tg1 = -80° C; Tg2 = 100° C Tg = 0.80 (-80) + 0.20 (100) = - 64 + 20 = - 44° C

Match the List-A (polymers) with List-B (their glass transition temperatures) -

List-A
List-B
P. Polycarbonate 1. - 125° C
Q. Polysulfone 2. 100° C
R. Polydimethylsiloxane 3. 147° C
S. Polystyrene 4. 185° C
  1. P - 1, Q - 2, R - 3, S - 4

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

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

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

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


Correct Option: C
Explanation:

Yes, it is correct. Polycarbonate has a glass transition temperature of about 147° C. Polysulphone describes a family of thermoplastic polymers. Its glass transition temperature is 185° C. Polydimethylsiloxane (PDMS) is a crystalline polymer with a glass transition temperature near -125° C. Polystyrene has a glass transition temperature of about 100° C.

Match the entries in Column-I (polymer additive) with those in Column-II (used as) -

Group-I
Group-II
P. 2-hydroxybenzophenone 1. UV stabiliser
Q. 2-mercaptobenzothiazole 2. Accelerator
R. Quinophthalone 3. Colourant
S. Dibromoneopentyl glycol 4. Flame retardant
  1. P - 1, Q - 2, R - 3, S - 4

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

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

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

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


Correct Option: A
Explanation:

All are correctly matched. 2-hydroxybenzophenone is used as UV stabiliser for polymers. 2-mercaptobenzothiazole is used as accelerator in vulcanisation. Quinophthalone (greenish yellow) is used as colourant in vinyls and polyolefins. Dibromoneopentyl glycol (DBNPG) is a brominated flame retardant commonly used as additives during the manufacture of plastic polymers.

Which of the following is/are examples of vinyl resin?

  1. BPA
  2. EPN
  3. PVA
  1. Only 1

  2. Only 2

  3. Only 3

  4. Only 1 and 2

  5. All of these


Correct Option: C
Explanation:

Poly vinyl alcohol (PVA) is a vinyl resin.

Match the entries in Group-I (commercial name of polymers) with that in Group-II (their chemical name) -

Group-I
Group-II
A. Nylon 6, 10 1. Poly(m-phenyleneisophthalamide)
B. Nomex 2. Poly(p-phenyleneterephthalamide)
C. Kevlar 3. Poly(hexamethylene sebacamide)
  1. A - 2, B - 1, C - 3

  2. A - 2, B - 3, C - 1

  3. A - 1, B - 2, C - 3

  4. A - 3, B - 1, C - 2

  5. A - 3, B - 2, C - 1


Correct Option: D
Explanation:

Yes, it is correct. Nylon 6,10 is commercial name of poly(hexamethylene sebacamide). Nomex is commercial name of poly(m-phenyleneisophthalamide). Kevlar is commercial name of poly(p-phenyleneterephthalamide).

Arrange the following polymers in increasing order of their glass transition temperature (Tg)?

  1. Poly(acrylic acid)
  2. Poly(zinc acrylate)
  3. Polymethylacrylate
  1. 1 < 2 < 3

  2. 1 < 3 < 2

  3. 2 < 3 <1

  4. 2 < 1 < 3

  5. 3 < 2 < 1


Correct Option: D
Explanation:

The presence of strong intermolecular bonds in a polymer chain, i.e., a high value of cohesive energy density, will significantly increase Tg. Intermolecular forces increases on going from the intermolecular forces in poly(methyl acrylate), an ester, through the strong hydrogen bonds in poly(acrylic acid) to primary ionic bonds in poly(zinc acrylate). Hence, Tg also increases in the order- polymethylacrylate (Tg = 3 °C) < poly(acrylic acid) (Tg = 106 °C) < poly(zinc acrylate) (Tg >400 °C).

Arrange the following polymers in increasing order of their glass transition temperature (Tg)?

  1. Polypropylene
  2. Poly(vinyl chloride)
  3. Polyacrylonitrile
  1. 1 < 2 < 3

  2. 1 < 3 < 2

  3. 2 < 3 <1

  4. 2 < 1 < 3

  5. 3 < 2 < 1


Correct Option: A
Explanation:

The presence of strong intermolecular bonds in a polymer chain, i.e., a high value of cohesive energy density, will significantly increase Tg. The steric effects of the pendant groups in given compounds (with side chains CH3, –Cl, and –CN) are similar, but the polarity increases. Consequently, Tg is increased in the order polypropylene ( Tg = –10 °C) < poly(vinyl chloride) (Tg = 87 °C) < polyacrylonitrile (Tg = 103 °C).

Which of the following sets represents synthetic polymers only?

  1. Pectin, Neoprene and Rayon

  2. Chitin, Neoprene and Orlon

  3. Nylon, Orlon and Rayon

  4. Nylon, Orlon and Teflon

  5. Starch, Rayon and Orlon


Correct Option: D
Explanation:

Yes. Nylon, Orlon and Teflon are all synthetic polymers.

Which of the following statements is/are true?

  1. Polycaprolactam has higher Tm than polycaprolactone.
  2. Polyethylene oxide has a higher crystalline melting temperature than polyethylene.
  3. Poly(1,4-cis-butadiene) has higher Tg than Poly(1,4-trans-butadiene).
  1. Only 1

  2. Only 2

  3. Only 3

  4. Only 1 and 2

  5. Only 2 and 3


Correct Option: A
Explanation:

The densities of the interunit linkages in polycaprolactone (ester units) and polycaprolactam (amide units) are the same. However, the amide units are more polar than the ester units. Consequently, polycaprolactam (226° C) has a much higher Tm than polycaprolactone (61° C).

Which of the following statements are incorrect?

P. Nylon 2–nylon 6 copolymer is non-biodegradable. Q. Glyptal is the addition polymer of ethylene glycol and phthalic acid. R. Urea formaldehyde resin is used in the making of unbreakable cups and laminated sheets. S. Bakelite is the condensation polymer of phenol and formaldehyde.

  1. Only P and Q

  2. Only P and R

  3. Only P and S

  4. Only Q and R

  5. Only Q and S


Correct Option: A
Explanation:

Nylon 2–nylon 6 is an alternating polyamide copolymer of glycine and amino caproic acid and is biodegradable. Glyptal is the condensation polymer of ethylene glycol and phthalic acid.

Which of the following polymers is/are obtained by chain growth polymerisation?

  1. Dacron,
  2. LDPE,
  3. Nylon, 6-6,
  4. PAN,
  5. Teflon
  1. Only 1 and 3

  2. Only 1, 3 and 5

  3. Only 2, 4 and 5

  4. Only 3 and 5

  5. Only 3, 4 and 5


Correct Option: C
Explanation:

Chain growth polymerisation - In this type of polymerisation, the molecules of the same monomer or different monomers add together on a large scale to form a polymer. The monomers used are unsaturated compounds, e.g. alkenes, alkadienes and their derivatives. Examples are- LDPE, HDPE, Teflon, PAN, etc.

Match the entries in Column-I (polymer additive) with those in Column-II (used as) -

Group-I Group-II
P. Tetrabromophthalic anhydride 1. Flame retardant
Q. Isoindoline 2. UV stabiliser
R. 2-hydroxybenzotriazole 3. Colorant
S. Dioctylphthalate 4. Plasticiser
  1. P - 1, Q - 2, R - 3, S - 4

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

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

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

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


Correct Option: B
Explanation:

Yes, it is correct. Tetrabromophthalic anhydride is a reactive flame retardant incorporated into unsaturated resins. Isoindoline is used as colorant in PVC and polypropylene and some engineering plastics. 2-hydroxybenzotriazole is used as UV stabiliser for polymers. Dioctylphthalate is used as PVC Plasticiser.

Which of the following compounds are used as PVC plasticiser?

P. Tricresyl phosphate Q. Diphenylguanidine R. Zinc butyl xanthate S. Dipropyleneglycol benzoate

  1. Only P and Q

  2. Only P and R

  3. Only P and S

  4. Only Q and R

  5. Only Q and S


Correct Option: C
Explanation:

Both are correct. Tricresyl phosphate and dipropyleneglycol benzoate are used as PVC plasticisers.

Which of the following statements are false regarding Styrene–Butadiene Rubber (SBR)?

P. SBR is produced by the free-radical polymerization of styrene and butadiene. Q. Cold SBR is better suited to adhesive formulation than hot SBR. R. Tire treads made from emulsion SBR are superior to those from solution SBR. S. The ozone resistance of SBR is superior to that of natural rubber.

Select the correct answer using codes given below:

  1. P and Q

  2. P and R

  3. P and S

  4. Q and R

  5. Q and S


Correct Option: D
Explanation:

Hot SBR is better suited to adhesive formulation than cold SBR. Hot SBR has a lower molecular weight and a broader molecular weight distribution than cold SBR. The lower molecular weight fraction provides quick stick, while the higher molecular weight fraction provides shear strength. On the other hand, narrow molecular weight distribution and higher trans structure of cold SBR make it less adaptable to adhesives.

Tire treads made from solution SBR are superior to those from emulsion SBR. Solution SBR has a higher molecular weight, narrower molecular weight distribution, and higher cis -1,4-polybutadiene content than emulsion SBR. These qualities reduce tread wear and enhance crack resistance of the tire.

Which of the following statements is/are incorrect?

  1. Styrene–butadiene block copolymer belongs to the A-B-A type thermosetting polymer.
  2. Cellulose ethers are more sensitive to hydrolysis than cellulose.
  3. Tetramethylthioureadisulfide is used as accelerator in vulcanisation of rubber.
  1. Only 1

  2. 2 only

  3. Only 3

  4. Only 1 and 2

  5. Only 2 and 3


Correct Option: D
Explanation:

Styrene–butadiene block copolymer belongs to the A-B-A type thermoplastic elastomer. The formation of cellulose ethers, unlike that of cellulose esters, is not reversible. Cellulose ethers are therefore less sensitive to hydrolysis than cellulose esters.

Match the entries in Group-I (Polymer) with those in Group-II (Poisson Ratio) -

Group-I
Group-II
P. Polypropylene 1. 0.37
Q. Polycarbonate 2. 0.45
R. Polytetrafluoroethylene 3. 0.32
  1. P - 1, Q - 2, R - 3

  2. P - 2, Q - 3, R - 1

  3. P - 2, Q - 1, R - 3

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

  5. P - 3, Q - 2, R - 1


Correct Option: D
Explanation:

Yes, it is the correct answer. Poisson ratio of polypropylene is 0.32. Poisson ratio of polycarbonate is 0.37. Poisson ratio of polytetrafluoroethylene is 0.45.

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