This set of Composite Materials Multiple Choice Questions & Answers (MCQs) focuses on “Thermoset Matrix”.
1. Epoxide groups are made up of _____ atom and ______ atoms.
a) 2 oxygen, 3 carbon
b) 2 oxygen, 2 carbon
c) 1 oxygen, 1 carbon
d) 1 oxygen, 2 carbon
View Answer
Explanation: Starting materials for epoxy matrix are low-molecular weight organic liquid resins containing a number of epoxide groups, which are three-member rings of one oxygen atom and two carbon atoms.
2. Which of the following is an example of step polymerization?
a) Polycarbonate
b) Polyethylene
c) Polyvinylchloride
d) Polyisopropene
View Answer
Explanation: In step polymerization, two reacting monomers are brought together to form a new molecule of the desired compound. Polycarbonate is an example of step polymerization and Polyethylene, Polyvinylchloride and Polyisopropene are some of the examples of additional polymerization.
3. Which of the following curing agent is used in the polymerization (curing) reaction to transform the liquid resin (diglycidyl ether of bisphenol A) to the solid state of epoxy polymer?
a) Diethylene triamine (DETA)
b) Diethylene biamine (DEBA)
c) Diamino diphenyl sulfone (DDS)
d) Diethyl ether
View Answer
Explanation: One of the curing agents is diethylene triamine (DETA). Hydrogen atoms in the amine (NH2) groups of a DETA molecule react with the epoxide groups of DGEB A molecules. As the reaction continues, DGEBA molecules form cross-links with each other and a three-dimensional network structure is slowly formed. The resulting material is a solid epoxy polymer.
4. Curing time in a polymerization reaction is also called as ________
a) Lifespan
b) Pot life
c) Cold life
d) False life
View Answer
Explanation: Time required to cure a resin from liquid state to solid state is called curing time which is also called as Pot time. Curing time and temperature to complete the polymerization reaction depend on the type and amount of curing agent.
5. Which one of the following epoxy resins is used as a starting material in aerospace industry?
a) Diglycidyl ether of bisphenol A (DGEBA)
b) Tetra-glycidal diamino diphenyl methane (TGDDM)
c) Diethylene triamine (DETA)
d) Diamino diphenyl sulfone (DDS)
View Answer
Explanation: Tetra-glycidal diamino diphenyl methane (TGDDM) is the starting material used in aerospace industry. It is cured with diamino diphenyl sulfone (DDS) with or without an accelerator. Diethylene triamine (DETA) is a curing agent used with Diglycidyl ether of bisphenol A (DGEBA) epoxy resin.
6. Which of the following curing agent is used in the polymerization of Tetra-glycidal diamino diphenyl methane (TGDDM)?
a) Diamino diphenyl sulfone (DDS)
b) Diethylene triamine (DETA)
c) Diglycidyl ether of bisphenol A (DGEBA)
d) Diethyl ether
View Answer
Explanation: Diamino diphenyl sulfone (DDS) is used as a curing agent in polymerization of TGDDM. The TGDDM–DDS system is used due to its relatively high glass transition temperature (240 8 C–260 8 C, compared with 1808C–1908 C for DGEBA systems).
7. Polyester matrix has the highest percentage of volume shrinkage within thermoset matrix.
a) True
b) False
View Answer
Explanation: Epoxy, Polyester and Vinyl ester are some of the thermoset matrix. Epoxy matrix has 1-5%, polyester matrix has 5-12% and Vinyl ester matrix has 5-10% of volume shrinkage.
8. On the application of heat, thermoset polymers cannot be reshaped into new structures.
a) True
b) False
View Answer
Explanation: Thermoset polymers have cross-linked or network structures with covalent bonds with all molecules. They do not soften, but decompose on heating and they do not reshape into any structure.
9. ______________ is used as a blending agent with epoxy resin to increase its glass transition temperature, modulus and tensile strength of epoxy resin.
a) Diamino diphenyl sulfone (DDS)
b) Diglycidyl ether of bisphenol A (DGEBA)
c) Polyether sulfone
d) Diethylene triamine (DETA)
View Answer
Explanation: Polyether sulfone is used as a blending agent. During polymerization the epoxy material gets toughen and thus decreases the glass transition temperature, modulus and tensile strength. Diethylene triamine (DETA) and Diamino diphenyl sulfone (DDS) are used as the curing agents. Diglycidyl ether of bisphenol A (DGEBA) is used as a starting material of epoxy.
10. The starting material for a thermoset polyester matrix is ______________
a) Saturated polyester resin
b) Unsaturated polyester resin
c) Saturated ester resin
d) Unsaturated vinyl resin
View Answer
Explanation: Unsaturated polyester resin contains a number of C=C double bonds. It is prepared by the reaction of maleic anhydride and ethylene glycol or propylene glycol.
11. The starting material for a thermoset polyvinyl matrix is ____________
a) unsaturated epoxy resin
b) Saturated vinyl ester resin
c) Unsaturated vinyl ester resin
d) Saturated polyester resin
View Answer
Explanation: Unsaturated vinyl ester resin produced by the reaction of an unsaturated carboxylic acid, such as methacrylic or acrylic acid and an epoxy.
12. Which of the following is used to reduce the viscosity of the resin?
a) Maleic anhydride
b) Styrene
c) Ethylene glycol
d) Glycerol
View Answer
Explanation: Styrene is a diluent with low viscosity, high solvency and low cost. Its drawbacks are flammability and potential health hazard due to excessive emissions.
13. The composite materials resulting from the suspension of nonmetallic particles in metal matrix is called as _________
a) Linear composites
b) Particulate composites
c) Cermet
d) Nonlinear composites
View Answer
Explanation: Nonmetallic particles in metal matrix results in composites called cermet. They are commonly classified into carbide-based and oxide-based composite materials.
14. Property of a material to withstand high temperature is called as ________
a) Corrosion resistance 0
b) Refractoriness
c) Acoustical insulation
d) Wear resistance
View Answer
Explanation: Refractoriness is a term used to signify the property of a material which can withstand high temperature. Titanium is a good example of refractoriness.
15. S.I unit of current density is _________
a) Kg/m2
b) m3/Kg
c) A/m
d) A/m2
View Answer
Explanation: S.I unit of current density is A/m2. Kg/m2, m3/Kg and A/m are the S.I units of surface density, specific volume and magnetic field strength respectively.
Sanfoundry Global Education & Learning Series – Composite Materials.
To practice all areas of Composite Materials, here is complete set of 1000+ Multiple Choice Questions and Answers.
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