This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Thermoplastic Polymers – 1”.
1. The thermoplastic is ____________
a) Cross-linked
b) Insoluble
c) Amorphous
d) Held by a covalent bond
View Answer
Explanation: Thermoplastics are linear or branched, soluble in suitable solvents, amorphous or semi-crystalline and held together by weak vander waal’s force or hydrogen bonds.
2. Which of the following is not an example of thermoplastic?
a) Nylon
b) Polyester
c) PVC
d) Vulcanised rubber
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Explanation: The examples of thermoplastic are nylon, polyester, PVC,PE, PP, PVA etc.
3. Polythene is prepared by the process of __________________ polymerisation of ethylene.
a) Addition
b) Condensation
c) Living
d) Free-radical
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Explanation: Polythene is prepared by the process of addition polymerisation of ethylene. Polythene is of low strength, hardness and rigidity, but has a high ductility and impact strength as well as low friction.
4. LDPE is prepared by polymerising ethylene at a pressure of ____________
a) 100-200 atmospheres
b) 1000-5000 atmospheres
c) 10-100 atmospheres
d) 2-10 atmospheres
View Answer
Explanation: None.
5. The crystallinity of LDPE is ____________
a) 10%
b) 30%
c) 55%
d) 80-90%
View Answer
Explanation: The crystallinity of LDPE is low (55%). LDPE is defined by a density range of 0.910–0.940 g/cm3.
6. Select the incorrect statement from the following option.
a) LDPE is chemically inert and has excellent chemical resistance
b) LDPE is tough and flexible
c) LDPE is used for making films in general packaging, carrier bags etc
d) LDPE has high rigidity and is suitable for load bearing applications
View Answer
Explanation: LDPE has low rigidity and is not suitable for load bearing applications. All other options are correct.
7. LDPE is suitable for the manufacture of pipes for distribution of gas.
a) True
b) False
View Answer
Explanation: LDPE is not suitable for the manufacture of pipes for distribution of gas because it is permeable to gas molecules. LDPE is widely used for manufacturing various containers, dispensing bottles, wash bottles etc.
8. The ethylene is polymerised under in the presence of ____________
a) Zeigler Natta catalyst
b) Supported metal oxide catalyst
c) Lewis acids catalyst
d) Friedel crafts catalyst
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Explanation: The ethylene is polymerised under 6-7 atmospheric pressure at 60-700C in the presence of Zeigler Natta catalyst.
9. The softening temperature of HDPE is ____________
a) 200C
b) 850C
c) 1350C
d) 1500C
View Answer
Explanation: The softening temperature of HDPE is 1350C. HDPE is known for its large strength-to-density ratio.The density of HDPE can range from 0.93 to 0.97 g/cm3 or 970 kg/m3.
10. Select the incorrect statement from the following option.
a) HDPE has excellent electrical insulation properties
b) HDPE is free from odour and toxicity
c) HDPE can be used for domestic water and gas piping
d) HDPE possess lower tensile strength compared to LDPE
View Answer
Explanation: HDPE possess greater tensile strength compared to LDPE. All the other options are correct.
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