PET, a polyester, is a chemical feedstock in polymer industry. Its synthesis may follow either of two ways. The starting chemical substance for the first route is terephthalic acid (TA). In the initial step, TA is reacted with glycol to give
diglycol-terephthalate and water. This route is called the TPA-route and can be classified as a condensation and esterification reaction.
Alternatively, dimethyl-terephthalate can be used in the first step, yielding
diglycol-terephthalate (again) and methanol. This is another condensation
reaction, this time a transesterification. It is called the DMT-route. The final
step on both ways to PET is polymerizing bis(hydroxyethyl)-terephthalate by eliminating half of the original amount of glycol in a transesterification and condensation reaction. The glycol produced here is redirected into step 1 of the
TPA or DMT-route.
28.12.2007
Artificial skin has been laboratory-grown on a polymer scaffold and can be used for healing chronic wounds of patients with ulcers caused by insufficient blood flow (Ulcus cruris).
-> More