Problem#$2$

Hydrolytic degradation under physiological conditions of polyester of $3-$hydroxybutyrate $(3$HB$)$

$($i$.$e$.$ when y$=0)$ and their random copolymers with $3-$hydroxyvalerate $(3$HV$)$ of different

percentage are measured. The structure of the polymers is shown. The degradation product of

the polyesters is predominantly $3-$hydroxybutyric acid. The wide angle X$-$ray diffraction pattern

and polymer degradation data are presented below.

A$.$ Explain the characteristic physicochemical properties of these polymers with respect to their

molecular structure

B$.$ Based on the degradation data, are these polymers exhibiting bulk or surface erosion. Use the

data to calculate the degradation rate constant $($density of all polymers are similar: $1\mathrm{.}22$ gm$/$cm$3).$

From the data, and calculations, explain whether the degradation is auto catalyzed, or non$-$auto

catalyzed.

C$.$ Based on physicochemical properties of these polymers explain the degradation

characteristics $($i$.$e$.$ both kinetics and physical character of the degradation$).$