This set of Composite Materials Multiple Choice Questions & Answers (MCQs) focuses on “Reinforcing Phase”.
1. The melting point of aluminum oxide (Al2O3) fiber is ____
a) 2045 °C
b) 1045 °C
c) 1145 °C
d) 2245 °C
View Answer
Explanation: Melting point of a material is a point at which it converts from solid state to liquid state. Aluminum oxide (Al2O3) fiber is an example of ceramic fiber which has a melting point 2045 °C and also good strength retention property up to about 1370 °C.
2. The shimmering appearance of silk is due to the presence of ________
a) Triangular prism in silk fiber
b) Dispersion prism in silk fiber
c) Deflection Prism in silk fiber
d) Offset prism in silk fiber
View Answer
Explanation: The triangular prism-like structure of the silk Fiber allows the silk to refract the incoming light at different angles and thus produce different colors. Dispersion prism, Deflection Prism and Offset prism are some of the types of prism in optics.
3. ______ is one of the strongest natural fibers.
a) Kenaf
b) Wool
c) Silk
d) Jute
View Answer
Explanation: Silk is one of the strongest natural fiber but it loses its strength up to 20% under wet conditions and has a good moisture regain property of 11%. Kenaf, Wool and Jute are some of the natural fibers.
4. Which of following is not a drawback of silk fiber?
a) Poor elasticity property
b) Moisture regain property
c) Attacked by the insects
d) Strength decreased due to sunlight
View Answer
Explanation: Silk fiber has a moisture regain property of 11%. It has poor elastic property for which it remains stretched for a small amount of elongation. Moreover, they are attacked by insects if found in dirty conditions and its strength weakens on exposure to too much sunlight.
5. Garments for firefighters, soldiers and other occupations where they are exposed to the likelihood of fire are made up of _________
a) Hemp
b) Sisal
c) Wool
d) Silk
View Answer
Explanation: Wool fiber has a lower rate of flame spread, lower rate of heat release, releases less toxic gases and acts as an insulating and self-extinguishing material. Hemp, Sisal and Silk are some of the natural fibers.
6. Which one of the following is called The Golden Fiber?
a) Wool
b) Silk
c) Jute
d) Cotton
View Answer
Explanation: Jute fiber is a 100% bio-degradable and recyclable natural fiber with golden silky shine property. It has high tensile strength, low extensibility, and ensures better breathability of fabrics.
7. Jute fibers are composed primarily of the plant materials cellulose and lignin.
a) True
b) False
View Answer
Explanation: Jute fibers are natural fibers composed of cellulose and lignin. Cellulose is an insoluble substance present in the cell walls of natural fibers and lignin is an organic substance which helps in binding the cells fibers and vessels.
8. To which of the following families does Hibiscus cannabinus belongs to?
a) Asteraceae
b) Poaceae
c) Urticaceae
d) Malvaceae
View Answer
Explanation: Malvaceae is the family of Hibiscus cannabinus and the fiber obtained from it is called kenaf. Asteraceae is the largest flowering plant family (sunflower). Poaceae is the family of bamboo which comes under the grass family and Urticaceae is a nettle family of Ramie.
9. The process in which the leaves are crushed and beaten by a rotating wheel set with blunt knives, so that only fibers are extracted is called as __________
a) Afforestation
b) Deforestation
c) Decortication
d) Ginning
View Answer
Explanation: Decortication is a process of removing the outer layer of a material in which the fibers are present beneath them. Afforestation is generally a process of planting more plants, Deforestation is a process of cutting down the trees and Ginning is the process of removing the seed from the cotton.
10. Heat resistance of Glass Wool is _____
a) 130-160 °C
b) 230-260 °C
c) 1200-1600 °C
d) 180-280 °C
View Answer
Explanation: Glass wool is a mineral fiber with the heat resistance of 230-260 °C used as an insulate piping and for soundproofing. Heat resistance is the property of a material to resist the flow of heat due to the temperature difference.
11. Which of the following Mineral Wool has the highest temperature resistant property?
a) Glass Wool
b) Ceramic Wool
c) Rock Wool
d) Stone Wool
View Answer
Explanation: Ceramic Wool has the highest temperature resistant property of 1200 °C, Glass Wool has 230-260 °C and Rock Wool also called as Stone Wool has 700-850 °C. Silicon carbide (SiC) and aluminum oxide (Al2O3) fibers are examples of ceramic fiber.
10. Property of a material to withstand high temperature is called as________
a) Corrosion resistance
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.
13. The protein fiber of silk is composed mainly of ________
a) Keratin
b) Fibroin and Sericin
c) Mohair
d) Royal-Wool
View Answer
Explanation: Silk emitted from silkworm consists of Fibroin and Sericin, Fibroin forms a structural center of silk which is made up of amino acids, and Sericin being the sticky material around structural center.
14. Composites made up of natural fibers and natural resin are called Green composites.
a) True
b) False
View Answer
Explanation: Green composites also called as bio-composites are composites in which both reinforcing agents and matrix agents are natural and bio-degradable.
15. Which of the following whiskers have the highest tensile stiffness (E)?
a) Copper
b) Silicon carbide
c) Nickel
d) Carbon
View Answer
Explanation: Carbon has the highest tensile stiffness of 980 GN/m2. Whereas copper, silicon carbide and nickel have 124 GN/m2, 840 GN/m2and 215 GN/m2 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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