This set of Composite Materials Multiple Choice Questions & Answers (MCQs) focuses on “Polymer Matrix”.
1. Which of the following is not a polymer matrix?
a) Epoxy
b) Urethane
c) Polyester
d) Aluminum
View Answer
Explanation: Aluminum is a metal which is well known for its low weight applications with specific weight of 2.7 g/cm3 and its tensile strength ranges from 90-690 MPa. Epoxy, Urethane and Polyester are some of the polymer matrix.
2. Which of the following is a drawback of polymer matrix composites?
a) High elastic properties
b) High operating temperature
c) High coefficients of thermal expansion
d) Low moisture expansion
View Answer
Explanation: Polymer matrix composites has a high coefficients of thermal expansion, which states for a minimum increase in temperature the composite expands rapidly. High elastic properties, High operating temperature and Low moisture expansion are some of the desired properties of polymer matrix composites.
3. S.I unit of Coefficient of thermal expansion is _______
a) KN/Kg°C
b) MPa
c) μm/m/°C
d) μin./in./°F
View Answer
Explanation: μm/m/°C is the S.I unit of Coefficient of thermal expansion where as μin./in./°F is also a unit of Coefficient of thermal expansion but in United States Customary System (USCS). MPa is the S.I unit of pressure.
4. Which of the following materials has the highest coefficient of thermal expansion?
a) Graphite/ epoxy composite
b) Glass/ epoxy composite
c) Steel
d) Aluminum
View Answer
Explanation: Aluminum has the highest coefficient of thermal expansion of 12.8 μm/m/°C. Graphite/ epoxy composite, Glass/ epoxy composite and steel have coefficient of thermal expansion of 0.01111, 4.778 and 6.5 μm/m/°C respectively.
5. Which of the following Glass fiber is used for electrical applications?
a) S-Glass
b) E-CR Glass
c) E-Glass
d) C-Glass
View Answer
Explanation: The “E” in E-glass stands for electrical because it was designed for electrical applications. The “S” in S-glass stands for higher content of silica. “E-CR” stands for electrical and corrosion resistance and used in those field. C-glass (“C” stands for corrosion) used in chemical environments, such as storage tanks.
6. _________% of silicon oxide is present in E-Glass.
a) 15
b) 17
c) 54
d) 40
View Answer
Explanation: 54% of silicon oxide, 15% of Aluminum oxide and 17% of Calcium oxide is present in E-Glass. S-glass has the highest content of silica with 64%.
7. Ultimate tensile strength of E-Glass fiber is greater than S-Glass fiber.
a) True
b) False
View Answer
Explanation: E-Glass and S-Glass are the classification of Glass fiber. E-Glass has the ultimate tensile strength of 3447 MPa whereas S-Glass has 4585 MPa.
8. Fracture toughness of Epoxy is greater than Aluminum alloys.
a) True
b) False
View Answer
Explanation: Fracture toughness of Epoxy is 3 MPa(m1/2) and aluminum alloy is of 35 MPa(m1/2).
Fracture toughness is the maximum load withstand by the material with a crack without any deformation.
9. 1 Å is equal to _______
a) 10-12m
b) 10-10m
c) 10-9m
d) 1012m
View Answer
Explanation: An angstrom (Å) is a unit of length and 1 Å = 10-10m. 1 picometer is equal to 10-12m, 1 nanometer is equal to 10-9m and 1 terahertz is equal to 1012m.
10. Which one of the following is not a precursor in the manufacturing of graphite fibers?
a) Rayon
b) Polyacrylonitrile
c) Pitch
d) Carbon
View Answer
Explanation: Carbon fibers have 93 to 95% carbon content but graphite has more than 99% carbon content. Graphite fibers are generally manufactured from three precursor materials: rayon, polyacrylonitrile (PAN), and pitch.
11. Ultimate tensile strength of PAN (Polyacrylonitrile) is _______
a) 3055 MPa
b) 3447 MPa
c) 1500 MPa
d) 2988 MPa
View Answer
Explanation: PAN is one of the precursors used for the manufacturing of graphite fibers. Ultimate tensile strength of a material is the maximum load withstand before the breakdown or fracture under tensile load condition.
12. ________% of maximum shrinkage can be seen during the curing of polyesters.
a) 10
b) 08
c) 05
d) 5.5
View Answer
Explanation: Polyesters are the polymers formed by the polymerization of esters. Curing is a process where polymer is converted from liquid state to solid state by cooling it. During curing process there is some percentage of reduction in dimensions of polymer, so called shrinkage of polymers.
13. ___________ are a ready-made tape composed of fibers in a polymer matrix.
a) Prepregs
b) Elastomers
c) PVC
d) PLA
View Answer
Explanation: Prepregs are available in standard widths from 3 to 50 in. Poly vinyl chloride (PVC) and Poly lactic acid (PLA) are some of the polymers. Elastomers are polymers with both elasticity and viscosity property.
14. During the curing of thermosetting resins, partial cross linkage can be seen in which of the following stages?
a) Stage A
b) Stage B
c) Stage C
d) Stage D
View Answer
Explanation: Thermosetting resins have three curing stages: A, B, and C. Stage A is called completely uncured stage with linear linkage of monomers. Partial cross linkage can be seen in Stage B and complete cross linkage in Stage C.
15. Which of the following matrix is a biodegradable polymer?
a) Carbon
b) PLA
c) Aluminum
d) Urethane
View Answer
Explanation: Poly lactic acid (PLA) is one of the biodegradable polymers with melting temperature of 180°C. Carbon, aluminum and urethane are some of the non-biodegradable materials.
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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