Chemistry

Polymers and Plastics

1,228 Questions

Polymers and plastics questions explore the properties, synthesis, and applications of various synthetic and natural polymers. Key topics include biodegradable plastics, vulcanization, and polymer nanocomposites. These concepts are frequently tested in science and engineering competitive exams.

Biodegradable plasticsPolymer nanocompositesVulcanization of rubberPolymer molecular weightAsphalt binders

Polymers and Plastics Questions

Multiple choice

Which of the following statements is/are false?

a. A polymer is a very big molecule formed by the combination of a large number of small molecules. b. Clothes made of synthetic fibers have a very smooth texture. c. Handle of a toothbrush should be made of thermoplastic and its bristles of thermosetting plastic.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This is the correct option as this statement is false. Handle of a toothbrush should be made of thermosetting plastic and its bristles of thermoplastic.

Multiple choice

Which of the following statements is/are false?

a. Thermoplastics are used for making those articles that may get too hot during use and are hard and rigid. b. In thermoplastics, the long polymer chains are not cross-linked with one another. c. Plastics are chemically unreactive and do not react with air and water.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is the correct option as this statement is false. Thermosetting plastics are used for making those articles that may get too hot during use and are hard and rigid.

Multiple choice

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

  4. 55° C
    • 55° C
Reveal answer Fill a bubble to check yourself
D Correct answer
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

Multiple choice

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
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

Multiple choice

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
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

Multiple choice

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
Reveal answer Fill a bubble to check yourself
D Correct answer
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).

Multiple choice

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
Reveal answer Fill a bubble to check yourself
D Correct answer
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).

Multiple choice

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
Reveal answer Fill a bubble to check yourself
A Correct answer
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).