This set of Polymer Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Types of Copolymerization”.
1. When is the copolymerization said to be an ideal copolymerization?
a) Copolymer composition F1 not equal to monomer feed composition f1
b) r1r2=1
c) r1=r2
d) r1=1
View Answer
Explanation: A copolymerization is said to be an ideal copolymerization when the chain radicals have equal preference to add one of the monomers over the other.
2. Which of the following is true if the two monomers involved in copolymerization, are equally reactive with each radical?
a) r1=r2=1
b) F1=f1
c) random arrangement of monomer units
d) all of the mentioned
View Answer
Explanation: When r1=r2=1, then under such condition, the monomers are equally reactive with chain radicals and the radicals cannot distinguish between the two monomers. Moreover, the composition of copolymer is the same as that in the feed and the monomer units are arranged in a random manner.
3. As the difference in the reactivities of the both significant monomers increases, an increasing difficulty in the production of copolymer is encountered as a result of ideal copolymerization. State true or false.
a) True
b) False
View Answer
Explanation: In case of r1>1 and r2<1 and vice versa, one of the monomer is more reactive than the other towards the propagating species resulting into the higher proportion of more reactive monomer unit in the copolymer formed. With larger differences in reactivities, the formation of copolymer becomes difficult as the more reactive monomer will undergo fast depletion from the monomer mixture.
4. Which of the following is correct regarding the alternate copolymerization?
a) r1r2=1
b) r1=r2=1
c) r1r2=0
d) r1r2>1
View Answer
Explanation: For perfect alternation in the copolymer structure the values of r1 and r2 are nearly equal to zero, as the chain growth strictly takes place by cross-propagation.
5. What is the value of copolymer composition (mole fraction), F1 for alternate copolymerization?
a) 0.5
b) 1
c) r1
d) 2
View Answer
Explanation: For alternation, r1=r2=0
And F1 = (r1f12+f1f2)/(r1f12+2f1f2+r2f22)
Substituting the values, we obtain F1= 0.
6. Which of the following combinations undergoing polymerization give polysulphones?
a) olefins and sulphur dioxide
b) cycloolefins and metal sulphate
c) olefins and sulphur trioxide
d) vinyl monomer and sulphur ring
View Answer
Explanation: Polysuplhones are obtained by the radical polymerization of monomers like olefins, cyclo-olefins, vinyl compounds in liquid sulphur dioxide.
7. Calculate the feed composition for azeotropic copolymerization of methy methacrylate and styrene at 60ᵒC.(Given that r1=0.46 and r2=0.52)
a) 0.47
b) 0.56
c) 0.235
d) 0.94
View Answer
Explanation: For azeotropic copolymerization,
(f1)c = (1-r2)/(2-r1-r2)
Substituting the values, we get (f1)c = 0.47.
8. What is the composition of copolymer formed by the copolymerization of 60% vinyl acetate and 40% vinyl chloride at 60ᵒC, given that r1=0.23 and r2=1.68?
a) 0.39
b) 0.78
c) 0.63
d) cannot be determined
View Answer
Explanation: The copolymer composition is calculated by the following equation-
F1 = (r1f12+f1f2)/(r1f12+2f1f2+r2f22)
Substituting the values, we obtain F1= 0.39.
9. What is the copolymer composition for azeotropic copolymerization of Acrylonitrile and 1,3-butadiene at 50ᵒC, given that r1=0.02 and r2=0.30?
a) 0.21
b) 0.417
c) 0.84
d) 0.62
View Answer
Explanation: For azeotropic copolymerization,
Critical feed monomer composition is given by-(f1)c=(1-r2)/(2-r1-r2)
Substituting the values, we get (f1)c=0.42
And copolymer composition is given by-
F1 = (r1f12+f1f2)/(r1f12+2f1f2+r2f22).
Thus, F1= 0.417.
10. Methacrylic acid and 2-vinyl pyridine are copolymerized together at 70ᵒC, where r1 and r2 have values 0.58 and 1.55, respectively. Which of the following component is present in more quantity in the copolymer formed in earlier stage?
a) methacrylic acid
b) 2-vinyl pyridine
c) equimolar composition
d) none of the mentioned
View Answer
Explanation: For the reaction of copolymerization, k1,1=0.58k1,2 and k2,2=1.55k2,1. In both the cases, 2-vinyl pyridine is consumed at a faster rate than methacrylate by each of the radicals. So 2-vinyl pyridine is present in more quantity in the copolymer formed at an earlier stage.
11. Which of the following polymerization proceeds without the change in the composition of feed as well as copolymer?
a) block polymerization
b) ideal polymerization
c) azeotropic polymerization
d) alternate polymerization
View Answer
Explanation: When the polymerization proceeds without a change in feed and copolymer composition, then there is an occurrence of azeotropic polymerization.
Sanfoundry Global Education & Learning Series – Polymer Engineering.
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