Condensation and Co-polymerization

Question 1

What are the other names for Auto acceleration

Answer 1

Gel effect
Tromsdorffourish effect

Question 2

What is Auto acceleration

Answer 2

Auto acceleration is a type of polymerization reaction that occurs when there is an increase in the viscosity of a growing polymer chain in such a way that it lead to a decrease in termination rate while propagation rate remains constant. This leads to a runaway reaction.

Question 3

What is a chain transfer reaction?

Answer 3

A chain transfer reaction occurs when additional processes happens alongside the polymerization reaction leading to the loss of free radicals and reduction of degree of polymerization.

Question 4

Condensation polymerization occurs in what medium?

Answer 4

Acidic medium.

Question 5

What are the sources of an acidic medium for condensation polymerization

Answer 5

1. Introduction of an external acidic medium.
2. One of the reactants plays a double role as a monomer and proton donor.

Question 6

What is co-polymerization

Answer 6

Co-polymerization describes polymers that are created with two or more repeating units as its monomer.

Question 7

Types of co polymer

Answer 7

Block aaaaaabbbbbbb
Graft a:b a:b a:b a:b a:b
Alternating abababababab
Random aababababbababbbababa

Question 8

What is reactivity ratio?

Answer 8

Reactivity ratio is a constant that describes the rate at which a monomer radical to adds its own monomer repeating unit or another monomer repeating unit to the growing copolymer.

Question 9

Formula for Ra

Answer 9

Ra = Rate at which radical A adds monomer A/ rate at which radical B add monomer A

Question 10

Describe the relationship between reactivity ratios and the copolymer formed

Answer 10

1. If R1R2 = 0, homopolymerization is not possible and they’ll form an alternating copolymer. However, a similar phenomenon is observed within the range of 0<R1R2<1. Within this range R1R2 = 0 is a perfect alternating copolymer and R1R2 = 1 is a perfectly random co-polymer.
2. If R1»»»»1 and R2««««1 then monomer 1 will be almost exclusively added until it is exhausted forming a block co-polymer.
3. If R1=R2=Infinity, co-polymerization is not possible.

Question 11

What are the methods of determining the molecular weight of a copolymer?

Answer 11

1. Number average: sum (MiNi/ni)
2. Weight average: Number average*Mi
3. Viscosity average