Tackifying polyesters by solid-state polycondensation

Solid-state polycondensation(SSP),for preparing particular high molecular weight polyesters(PET,PTT,and PBT),are carried out by heatiing the low molecular weight prepolymers in the form of chips in a stream of gas or under vacuum at a temperature above the polymer glass transition but below the melting point.On the basis of studies on the mechanism of SSP of polyesters,the continuous and batch SSP processes are applied industrially.