This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Polymer Blends”.
1. The physical mixture of two or more polymers that are not linked by covalent bonds is called ____________
a) Polymerisation
b) Dendrimer
c) Polyblend
d) Multiblend
View Answer
Explanation: The physical mixture of two or more polymers that are not linked by covalent bonds is called polyblend or polymer blend. They are blended together to create a new material with different physical properties.
2. Polymers are dissolved in common solvent to give ____________
a) Mechanical blends
b) Solution-cast blends
c) Latex blends
d) Chemical blends
View Answer
Explanation: Polymers are dissolved in common solvent to give solution-cast blends. If the blend is made of two polymers, two glass transition temperatures will be observed.
3. For amorphous and semi-crystalline polymers, mixing leads to the formation of ____________
a) Mechanical blends
b) Solution-cast blends
c) Latex blends
d) Chemical blends
View Answer
Explanation: For amorphous and semi-crystalline polymers, mixing leads to the formation of mechanical blends. The macroscopically uniform properties are usually caused by sufficiently strong interactions between the component polymers.
4. The immiscible blends exhibit ____________
a) Excellent mechanical properties
b) Poor mechanical properties
c) Poor chemical properties
d) Intermediate chemical properties
View Answer
Explanation: The immiscible blends exhibit poor mechanical properties. This is by far the most populous group. If the blend is made of two polymers, two glass transition temperatures will be observed.
5. Cross-linked polymers are swollen with a different monomer, which results in ____________
a) Mechanical blends
b) Solution-cast blends
c) Latex blends
d) Chemical blends
View Answer
Explanation: Cross-linked polymers is swollen with a different monomer, which results in chemical blends. They have different chemical properties.
6. Select the incorrect option from the following option.
a) Immiscible blends are usually opaque
b) Immiscible blends exhibit a single glass transition temperature (Tg) intermediate between those of individual components
c) Miscible blends are usually clear
d) Immiscible blends exhibit separate Tg’s characteristics of each component
View Answer
Explanation: Miscible blends exhibit a single glass transition temperature (Tg) intermediate between those of individual components. All the other options are correct.
7. (PPO + PS) polyblend is commercially available engineering plastic Noryl (General Electric).
a) True
b) False
View Answer
Explanation: (PPO + PS) polyblend is commercially available engineering plastic Noryl (General Electric). The use of the term polymer alloy for a polymer blend is discouraged, as the former term includes multi-phase co-polymers but excludes incompatible polymer blends.
8. Fine dispersions of polymers in water are mixed and coagulated to give ____________
a) Mechanical blends
b) Solution-cast blends
c) Latex blends
d) Chemical blends
View Answer
Explanation: Fine dispersions of polymers in water are mixed and coagulated to give latex blends. The use of the term polymer alloy for a polymer blend is discouraged, as the former term includes multi-phase co-polymers but excludes incompatible polymer blends.
9. The blend is said to be synergistic for the mechanical property if the term (I) in the empirical formula is?
a) Zero
b) Positive
c) Negative
d) Imaginary
View Answer
Explanation: The blend is said to be synergistic for the mechanical property if the term (I) in the empirical formula is positive. For amorphous and semi-crystalline polymers, mixing leads to the formation of mechanical blends.
10. The blend is said to be additive for the mechanical property if the term (I) in the empirical formula is ____________
a) Imaginary
b) Positive
c) Negative
d) Zero
View Answer
Explanation: The blend is said to be additive for the mechanical property if the term (I) in the empirical formula is zero. For amorphous and semi-crystalline polymers, mixing leads to the formation of mechanical blends.
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