ITECH 25Oct2021

The most prevalent type of chain reactions is free radicalar polymerization

• True

• False

Free radicals are formed from

• the homolytic cleavage of waek bonds

• only the homolytic cleavage of covalent bonds

• the homolytic cleavage of covalent bonds as well as numerous radiation-associated methods

• only radiation-associated methods

A free radical is

• a chemical specie that has two electrons (usually very reactive)

• a chemical specie that has one free unpaired electron (usually very reactive)

• a non reactive specie

• an intermediate specie, atomic or molecular that has two electrons

In chain polymerization processes, the active center is retained at the middle of a growing polymer chain and monomers are added to this center in rapid succession.

• True

• False

The rate of addition of monomers to the active center relative to the overall conversion of the monomer to polymer is quite slow

• True

• False

In radicalar polymerization, high-molecular-weight polymers are generated even while most of the monomers remain intact

• True

• False

Polymers formed at the initial stage of the reaction are little affected by the extent of reaction and are of comparable molecular weight with those formed later in the reaction

• True

• False

The acquisition of the active site by the monomer is known as

• the initiation step

• the propagation step

• the termination step

• chain transfer effect

The destruction of the growth activity of the chain will lead to the

• polymer and it is called step growth polymerization

• polymer and it is called propagation step in chain growth polymerization

• polymer and it is called initiation step in chain growth polymerization

• polymer and it is called termination step in chain growth polymerization

In the study of Kinetics of Radicalar Polymerization, we assume that

• there is just head-to-head propagation sub-steps, all with the same speed.

• there is just head-to-tail propagation sub-steps, but all with different speed.

• there is just head-to-tail propagation sub-steps, all with the same speed.

• there is just tail-to-head propagation sub-steps, all with the same speed.