Modelling of polyethylene terephthalate reactors-X. A comprehensive model for solid-state polycondensation process

Abstract

A new comprehensive model for solid-state polycondensation (SSP) of polyethylene terephthalate (PET) has been developed, which interprets a number of hitherto unexplained observations. Degradation and other side reactions which were neglected in the earlier models for SSP process of PET are included. The diffusivity changes due to crystallisation of PET, the true influence of nature of carrier gas and the increase in the reactive chain end group mobility due to the change in the free volume in the presence of an inert gas have been considered. The model predictions have been validated with experimental data reported in the literature. The model can be used for a quantitative prediction of the influence of a variety of parameters on the degree of polymerisation as well as side products formation. The model correctly brings out the true influence of the carrier gas which had remained unexplained so far. It also suggests additional directions for improving the SSP process.