Modelling of reversible poly(ethylene terephthalate) reactors

✍ Scribed by A. Kumar; S. K. Gupta; B. Gupta; D. Kunzru

• Publisher: John Wiley and Sons
• Year: 1982
• Tongue: English
• Weight: 850 KB
• Volume: 27
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1982.070271131

✦ Synopsis

The second stage of batch poly(ethy1ene terephthalate) (PET) reactor with bis(2-hydroxyethyl) terephthalate (BHET) as the feed has been simulated. In this stage, the overall polymerization is not diffusion limited and is known to be a complex reaction. In this work it has been assumed to consist of polycondensation, reaction with monofunction4 compounds (cetyl alcohol), redistribution, and cyclization reactions The forward and reverse. steps of each of these have been modelled in t e r n of the rate constants involving functional group and the reacted bonds. The equations for the calculation of the molecuiar weight distribution (MWD) in batch reactom have been written and solved numerically. The MWD reported in this work is assumed to include the monofunctional products only, and, for the case where ethylene glycol is not removed from the reaction mass, it was found to be unaffected by the choice of the redistribution rate constant (kr). Since the removal of ethylene glycol is not maas transfer controlled, its concentration in the reaction mass is assumed be given by the vapor-liquid equilibrium existing at the pressure applied on the reactor. In this work, the level of ethylene glycol concentration. y , (I (G]/(PJ& has been taken as a parameter, and, on application of vacuum, the MWD resdta were found to vary with k, with the sensitivity increasing with yr. It was then shown that the importance of the redistribution reaction is enhanced when the cyclization reaction also OCCUR. The effect of vacuum on the performance of the reactor has been studied by varying ye For y, less than 0.01, the change in the MWD of the polymer becomes very small. The effects of polymerization temperature and initial concentration of monofunctional compounds on MWD were found to be small.