When an equilibrium step-growth polymerization is 99% complete, what fraction of the reaction mixture is still monomer (a) on mole basis and (b) on weight basis ?

(a) Compute the repeat unit molecular weight of polybutene unit chemical formula =( C8H16) (b) Compute the number-average molecular weight for a polybutene for which the degree of polymerization is 24,000.

Monomers/initators used in free radical polymerization i) What monomer can be used with benzoyl peroxide and under what conditions? ii) What monomer can be used with di-tert-butyl peroxide and under what conditions? iii) What monomer can be used with hydrogen peroxide and under what condition?

d) Early in the polymerization at lower conversion of the MVK monomer, the polymer chains formed are primarily linear. However, close to the end of the reaction, as most of the monomer is consumed, branched polymers may start to appear. Propose a possible rationale for the formation of branched polymer structures (hint: consider the types of termination reactions that may compete with polymerization when only little monomer is still present). 로 3 3 linear vs. branched

1. What is Tacticity, show syndiotactic, isotactic and atactic polymer. Which is easiest to crystallize and why.

Some polymeric materials are opaque and some are clear and tranparent. Explain why.

Identify which of the following pairs of monomers could be used in condensation polymerization. Select one: H K. H H O-H H-C-C HO CH ₂ CH K OH HHHH | | | | H-C- H -C-C-0-H | | | | HHHH H J H HO- H -OH H 44 H X C H H

Draw a log E – temperature plot for a linear, amorphous polymer.(a) Indicate the position and name the five regions of viscoelastic behavior.(b) How is the curve changed if the polymer is semicrystalline?(c) How is it changed if the polymer is cross-linked?(d) How is the curve changed if the molecular weight is increased significantly?(e) How is it changed if the experiment is run at higher frequency—that is, if  measurements are made after 10 Hz rather than 1 Hz