Chemistry short questions: Polymers (set-2)

Q.1 What are co-polymers?

Ans. A polymer having two or more than two divergent monomers that binds with each other in a random sequence as a building block of long chain macro molecule.

Q. 2 What is glass transition temperature?

Ans. The temperature at which a polymer starts possessing glassy state and becomes rigid, stiff and brittle is known as glass transition temperature.

Q. 3 What is critical chain length?

Ans. Critical chain length is the minimum length needed for the entanglement of chain of the polymer.

Q. 4 What is an atactic polymer?

Ans. When the arrangement of pedant groups at both sides of a polymer chain is random then the polymer is known as atactic polymer.

Q. 5 What is threshold molecular weight?

Ans. It is the minimum weight molecule weight of a polymer needed to attain the characteristic properties of polymers like toughness, rigidness and brittleness.

 Q. 6 What is polymer fractionation?

Ans. In this process polymer sample is separated into fractions to get homogeneous mixtures.

Q. 7 Why molecular weight of a polymer is taken as average molecular weight?

Ans. A polymer is a combination of heterogeneous and polydisperse units having divergent molecular weights. Thus, average molecular weight of its constituent units is taken.

Q. 8 What is calendering?

Ans. The process of manufacturing polymeric sheets with the help of counter rotating rolls of a machine is called calendering.

Q. 9 What is relaxation time in polymerization?

Ans. The time needed to stress a polymer under constant high strain to drain 1/e or 0.37 of original stress. It is a time dependent decrease in stress providing constant levels of strain.

Q. 10 What is plasticizer?

Ans. It is an additive material which is added as a lubricant to reduce the inter-molecular forces among polymer chains. Addition of plasticizers decreases the brittleness on one hand and increases the flow rate on the other hand.