This set of Polymer Engineering Questions and Answers for Entrance exams focuses on “Additives for Plastics”.
1. Which of the following type of fillers are treated with chemicals to improve its attachment with polymers?
a) particulate fillers
b) rubbery fillers
c) mineral fillers
d) fibrous fillers
Explanation: Mineral fillers are usually treated with specific chemicals to improve wettening and attachment with polymers to fillers. Stearic acid-treated calcium carbonate or amine- or glycol-treated clays are some examples of mineral fillers.
2. Which of the following additives are used in the least amount with polymer in general?
c) cross linking agents
Explanation: Lubricants are used in the least amount among the other additives. Generally, 1-2 parts by weight of lubricants is used per 100 grams of polymer, while 30-100 and 2-5 parts by weight of plasticizers, fillers and cross-linking agents, respectively are used per 100 parts of polymer.
3. Which of the following filler is used as a reinforcing agent for the polymers?
a) wood flour
b) carbon black
Explanation: Wood flour is a fibrous filler that is a mixed with polymers to be used as a reinforcing agent.
4. Which property of polymer is enhanced by the use of mica as filler?
b) heat resistance
d) impact resistance
Explanation: The use of mica, asbestos, glass fibre, etc is used as filler to improve heat resistance of polymers.
5. Which of the following additives are available as high boiling non volatile liquids?
d) colouring matters
Explanation: Plasticizers are usually high boiling nonvolatile liquids. They are used in variety of polymers such as cellulosics, acrylics and poly(vinyl) chloride. Fillers are usually solid additives while colouring matters are generally pigments and dyes.
6. What kind of additives prevent the degradation of polymers while their processing and storage?
b) cross-linking agents
Explanation: Stabilizers like antioxidants and UV absorbers are used as additives in polymers to protect them from degradation during storage and processing applications under performing conditions.
7. Which of the following stabilizer is capable of preventing the polymer from UV degradation?
a) phenyl napthylamines
b) dilauryl thiopropionate
c) styrenated phenols
d) phenyl salicylates
Explanation: Phenyl salicylates is a UV absorber which gives protection against UV degradation to polymers while dilauryl thiopropionate, styrenated phenols and phenyl napthylamines are antioxidants that prevent degradation by oxygen attack.
8. What is the use of carbon black in polymer compounding to improve as an additive?
a) as a filler
b) as a colourant
c) as a stablizier
d) all of the mentioned
Explanation: Carbon black is used as a filler to influence the properties of final product, as a stabilizer UV absorber to avoid UV degradation and also as a colourant in polymer compounding.
9. Which of the following materials work as a polymeric flow promoters?
a) glyceryl stearates
b) calcium stearate
c) stearic acid
d) silicone fluids
Explanation: Glyceryl stearates are low molecular weight materials that impart better flow properties to the polymer mix under processing conditions without really affecting the bulk properties under service conditions.
10. Which of the following additive can act as curing agent for epoxides?
d) all of the mentioned
Explanation: Amines and polyamines are used as curing agent for epoxides, sulphur for diene rubbers and formaldehyde for novolacs and polyvinyl alcohols.
11. Which property of polymer is enhanced by adding antimony oxychloride as an additive?
a) flame retardancy
b) buildup of static electricity
Explanation: Antimony compounds like antimony oxychloride work as flame retardants to enhance flame retardancy in plastics. They decompose endothermically and form impervious fire resistant layer on the surface thus preventing access of oxygen to the inner polymer layers.
12. Which of the following compounds are used as antistatic agent?
a) sulphur compounds
b) ammonium compounds
c) chlorinated compounds
d) none of the mentioned
Explanation: Selected amines and quaternary ammonium compounds are used as antistatic agents while chlorinated paraffins are used as flame retardants in polymer compounding.
13. Which of the following is used as a chemical blowing agent in polymers?
a) trixylyl phosphate
c) antimony oxide
d) none of the mentioned
Explanation: Azonitrile is a commonly used chemical blowing agent while antimony oxide and trixylyl phosphate are used as flame retardants in polymers.
Sanfoundry Global Education & Learning Series – Polymer Engineering.
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