Ethylene distillation-condensation polymerization

A polymerization such as this is called a melt condensation because the reaction is run neat, meaning no solvents are used. Thus there is no need to purify the polymer at the end, and all leftover monomers are either converted to polymer or distilled from the reacton Reactions like this are sometimes called green because of their relatively low demands on the environment. The yield is 100% and there are no side reaction products that need to be removed. Because no solvents are used, none escape into the air or the sewen The product does not have to be isolated from a solution, a process that would require energy. The methanol and excess ethylene glycol that are distilled from the... 

Polymerization of PET is different from the polyolefins described previously. It is formed by a condensation reaction between two monomers dimethyl terephthalate (DMT) and ethylene glycol (EG). The polymerization process involves a two-step process ester interchange (Eq. [2.3]) and polymerization (Eq. [2.4]). Weak basic catalysts, usually metal salts, are used to accelerate polymerization and control the molecular weight and stoichiometry of the polymer. The first step is carried out at temperatures from 150 to 200°C and the methanol is continuously distilled off. The reaction is a solution polymerization. The temperature in the second step is increased to 260—290°C, at which melt polymerization occurs (Odian, 1981). 

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