Problem II $1(30$pts$)$

a$)$ What are the differences between the kinetic chain length, $v_n$ and the number$-$average degree of polymerization, $x_n?$

b$)$ The differences between Stepwise and chainwise $($living & usual$)$ polymerization are shown in figure #$1.$

Explain the reasons for such differences in the polymer concentration and D$,$ profiles?

Problem #$2(35$pts$)$

$25gm.$ of Benzoyl peroxide, $,$ was used as an initiator for a free$-$radical polymerization to react vinyl acetate, VA monomer, to form high molecular weight polyiny acetate PVA at $60C.$ The polymerization reaction started with $5kg$ of VA in a five$-$liter batch reactor. What is the VA concentration at $20$min from the start of the reaction?

Problem $1(35$ pts$)$

in a copolymer reaction for a system of methyl methacoylate "MMA" $(1)$ and vinyl chloride $"$VC$"$

$(2)$ at $60C$ the reactivity ratios were $r_1=8$ and $r_2=2$

a$-$ If the MMA monomer feed composition was $33\%,$ then, calculate the initial copolymer compositions?

b$-$ It is required to produce copolymer of this system that consists of $75\%$ MMA monomer as initial concentration, calculate how much monomer feed composition we should start with?