1. What approx proportion of third diene monomer is added to produce EPDM rubber?
a) 9-10%
b) 4-5%
c) 19-20%
d) 12-15%
Explanation:EPDM ruuber is a terpolymer formed by the copolymerization of a non-conjugated diene as a third monomer in small proportions, upto 5%, along with ethylene and propylene.
2. Which of the following does not resemble to EPDM rubbers?
a) high density
b) moderate tear strength
c) good heat stability
d) good storage stability
Explanation: EPDM rubbers have low density around 0.85 gram per cubic centimeters.
3. Which of the following is used as curing agent for acrylate rubbers?
a) sulphur
b) zinc oxide and stearic acid
c) aliphatic amines and polyamines
d) metal peroxides
Explanation: Acrylate rubbers are readily cured using aliphatic linear amined and polyamines.
4. What is the monomer composition of polymer named Vamac?
a) methyl acrylate, ethylene, curing site monomer
b) propylene, ethylene, ethyl acrylate
c) ethyl acrylate, ethylene
d) ethyl acrylate, ethylene, cure site monomer
Explanation:A terpolymer of methyl acrylate, ethylene and a cure site monomer is known as Vamac in the trade.
5. Which monomer pairs copolymerize to give nitroso rubber?
a) trifluoronitrosomethane and tetrafluoroethylene
b) tetrafluoronitrosomethane and trifluoroethylene
c) trifluoronitrosomethane and trifluoroethylene
d) tetrafluoronitrosomethane and tetrafluoroethylene
Explanation: Nitroso Rubber is an alternating copolymer of trifluoronitrosomethane and tetrafluoroethylene of high molecular weight
6. A rubber polymer sample A is reacted with chromic acid solution and yields acetic acid solution. Compound A also gives positive Weber test. Which of the following is possibly A?
a) 1,4-polyisoprenes
b) butyl rubber
c) nitrile butadiene rubber
d) all of the mentioned
Explanation: 1,4-polyisoprenes yield acetic acid with chromic acid solution which is identified by its odour. It also gives positive weber test.
7. Which of the following does not give positive weber test of rubbers?
a) natural rubber
b) butyl rubber
c) polyisoprene rubber
d) styrene butadiene rubber
Explanation: In weber test, acetone-extracted polymer is dissolved in carbon tetrachloride with little bromine solution and then heated to remove excess bromine. The residue is then warmed in little phenol. The solution turns violet or purple due to presence of poluisoprenes, and so his test is positive for NR, IR and butyl rubber.
8. Polysulphide rubbers when treated with trichloroacetic acid imparted colour X, which turned to colour Ysolution on boiling and then colour Z precipitate on dilution. Which set of colours represent X, Y, Z, respectively?
a) pink, red-brown, grey
b) pink, ruby-red, rose-pink
c) pink, red-brown, yellow
d) pink, ruby-red, yellow
Explanation:Polusulphide rubbers give pink colour on treatment with trichloroacetic acid which turns ruby-red solution on boiling, giving rose-pink precipitate on dilution
9. Which of the following rubbers when treated with trichloroacetic acid give pink-mauve melt and on dilution give grey-mauve precipitate?
a) isomerized rubber
b) acetone-extracted NR
c) gutta percha
d) all of the mentioned
Explanation:Acetone-extracted NR, isomerizaed rubber and gutta percha when warmed with trichloroacetic acid give pink-mauve melt and on dilution with water result in grey-mauve precipitate.
10.Which of the following rubber do not respond to trichloroacetic acid?
a) isomerized rubber
b) chlorinated rubber
c) polysulphide rubber
d) butyl rubber
Explanation: Chlorinated rubber does not produce any effect when treated with trichloroacetic acid.