This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Fibers – I”.
1. The tensile strength of the fiber is
a) Very Low
Explanation: The tensile strength of the fiber is high and depends upon the strength of chemical bonds of the polymer chains.
2. Which of the following type of bonding maintains the alignment of chains of the polyester?
a) Vander Waal’s force
b) Dipole-dipole attraction
c) Hydrogen bonding
d) Covalent bonding
Explanation: Dipole-dipole attraction are induced due to the dipole formed by alignment of negative and positive charges and hence this type of bonding maintains the alignment of chains of the polyester.
3. Nylon-66, PET and PAN all have Tg around
a) 100 0C
b) 200 0C
c) 300 0C
d) 500 0C
Explanation: Nylon-66, PET and PAN all have Tg around 100 0C. The glass-transition temperature Tg of a material characterizes the range of temperatures over which this glass transition occurs. It is always lower than the melting temperature, of the crystalline state of the material, if one exists.
4. Hydrogen bonding is responsible for maintaining the alignment of
a) Stereoregular chains of isotactic polypropylene
Explanation: Hydrogen bonding is responsible for maintaining the alignment of polyamides and polyurethanes. Polyamides are polymer of a type made by the linkage of an amino group of one molecule and a carboxylic acid group of another.
5. Nylon-6 can be prepared by ring opening polymerisation of
a) Amino caproic acid
c) Adipic acid
d) Terephthalic acid
Explanation: Nylon-6 can be prepared by ring opening polymerisation of caprolactum. Caprolactum has 6 carbons and hence, Nylon-6.
6. Which of the following is the third step for the synthesis of nylon-6?
a) Conversion of cyclohexane into cyclohexanone
b) Ring opening polymerisation of caprolactum
c) Conversion of cyclohexanone-oxime into caprolactum
d) Conversion of cyclohexanone into cyclohexanone-oxime
Explanation: Conversion of cyclohexane into cyclohexanone is the initial step. Then the second step is the conversion of cyclohexanone into cyclohexanone-oxime and then the conversion of cyclohexanone-oxime into caprolactum is the third step for the synthesis of nylon-6. Ring opening polymerisation of caprolactum is the last step.
7. The cyclohexanone is converted into cyclohexanone-oxime by
a) Treatment with hydroxylamine
d) Backmann rearrangement
Explanation: The cyclohexanone is converted into cyclohexanone-oxime by treatment with hydroxylamine because hydroxylamine act as catalyst for this reaction. This is the second step for the synthesis of Nylon-6.
8. Nylon-6,6 is made by the condensation polymerisation of hexamethylene diamine and adipic acid in the molar ratio of
a) 2 : 3
b) 1 : 2
c) 3 : 5
d) 1 : 1
Explanation: Nylon-6, 6 is made by the condensation polymerisation of hexamethylene diamine and adipic acid in the molar ratio of 1 : 1. Equivalent amounts of hexamethylene diamine and adipic acid are combined with water in a reactor.
9. The nylon-6, 6 have high crystallinity which imparts
a) Low strength
b) Low meting point
c) Toughness and elasticity
d) Retention to poor mechanical properties
Explanation: The nylon-6, 6 have high crystallinity which imparts high strength, high melting point, elasticity, toughness and retention to good mechanical properties.
10. Nylons are polar polymers and have good hydrocarbon resistance.
Explanation: Nylons are polar polymers and have good hydrocarbon resistance. Nylon resins are widely used in the automobile industry especially in the engine compartment.
Sanfoundry Global Education & Learning Series – Engineering Chemistry.
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