Copolymerization and Polymerization Techniques - Polymer Chemistry - Engineering Sciences Previous Year Questions

For free radical copolymerization of monomers M₁ and M₂, if the reactivity ratios r₁ and r₂ are both found to be zero, then the resulting copolymer is

Determine the mole fraction of vinyl chloride in a copolymer of vinyl chloride (CH₂CHCl) and vinyl acetate (CH₂CH-OCOCH₃) having molecular weight of 10520 g/mol and degree of polymerization of 160.

Match the following for free-radical copolymerization of two monomers with reactivity ratios, r₁ and r₂.

Reactivity Ratios	Copolymer Nature
P. r1 = r2 = 0	1. Random copolymer
Q. r1 = r2 = 1	2. Alternate copolymer
R. r1 > 1, r2 > 1	3. Block copolymer
S. 0 < r1r2 < 1	4. Random-Block copolymer

The monomers, A and B with reactivity ratios r_A and r_B, form alternate copolymers when,

The copolymer(s) among high density polyethylene (HDPE), low density polyethylene (LDPE) and linear low density polyethylene (LLDPE) is/are

An alternating copolymer has number-averaged molecular weight of 10⁵ g mol⁻¹ and degree of polymerization of 2210. If one of the repeat units is ethylene, the other one is
(Given: atomic weight of H = 1, C = 12, F = 19 and Cl = 35.5)

The propagation step of a free radical copolymerization is represented by the following possible reaction steps:
P1: M1* + M1 → M1*, rate constant = k11
P2: M1* + M2 → M2*, rate constant = k12
P3: M2* + M1 → M1*, rate constant = k21
P4: M2* + M2 → M2*, rate constant = k22
where, M1 and M2 are two monomers and M1* and M2* are the active radicals of M1 and M2, respectively. kij (i,j = 1, 2) represents the rate constant of each step as shown above.
If the reactivity ratios of M1 and M2 are expressed as: r1 = k11/k12 and r2 = k22/k21, respectively, and feed mole ratio, F is expressed as F = [M1]/[M2] (where, [M1] and [M2] are the concentrations of M1 and M2, respectively), the probability of the reaction P2 is ______.

In a set of copolymerization reactions, the following monomer reactivity ratios r1 and r2 were found for different cases.

Case	r1	r2
I	0.1	10
II	0.003	0.02
III	3.4	5.6
IV	51	0.01

Which option(s) correctly identify/identifies the type of copolymerization corresponding to each Case?