'Polyethylene terephthalate $($PET$)$ is a plastic resin and is the most common type of polyester

used commercially. It is also one of the most recycled plastics in the market. Soon after its

commercial production in $1953$ by DuPont, PET became the most widely produced synthetic

fiber in the world. Later in the $1970$s$,$ the development of stretch$-$molding procedures facilitated

the bulk production of PET into durable crystal$-$clear beverage bottles $-$ an application that soon

became second in importance only to fiber production. PET technology has advanced to such a

level today that its presence is felt in almost every application.$\text{'}$ Dasan, K$.$ P$.(2015).$ PET

Nanocomposites: Preparation and Characterization. In Poly $($Ethylene Terephthalate$)$ Based

Blends, Composites and Nanocomposites $($pp$.99-111).$

The molecular structure is given below:

Experimental chain dimentions for PET at $275C$ are given by $\frac{(\text{:}{h}^2\text{:}{)}_o}{M}$~~$0\mathrm{.}90{}^{2}mo\frac{l}{g}.$

Estimate the radius of gyration, $C_{},$ the statistical segment lenght, and the persistance lenght

for this commercially important polymer. Also find the force needed to extend the single chain

PET of $M=100,000$ three times its equilibrium end$-$to$-$end distance. Based on these numbers, is

PET a flexible polymer? What would you expect based on the molecular structure?