The formation of polyethylene terephthalate by ester interchange. III. The kinetics of the redistribution reaction
The formation of polyethylene terephthalate by ester interchange. III. The kinetics of the redistribution reaction
- Die Makromolekulare Chemie: MacroMolecular Chemistry and Physics, 38(1), p.138-146, 1960 .
The so-called redistribution reaction between end-groups and chain bonds cannot be studied by the usual functional group analysis. A novel method for direct kinetic investigation of this reaction is presented and applied to a known low-polymeric polyethylene terephthalate free from monomer. During condensation polymerization the production of monomer is determined quantitatively through fractional vacuum sublimation. The contribution of reversible polycondensation to the monomer production is derived from the results of a previous kinetic study of the reversible polycondensation starting from the same precondensate. From the difference with the experimentally established monomer production, evaluation of the redistribution rate constant kr is possible. From the values of kr at 223 and 254°C. and activation energy of ?? 31 kcal./mole is calculated. At these temperatures kr is of the same order of magnitude as the rate constants of reversible polycondensation yet. At the normal manufacturing temperature of 280°C. redistribution proceeds considerably faster than polycondensation, thus rendering a rather quick restoration of a normal molecular size distribution if not present initially
The so-called redistribution reaction between end-groups and chain bonds cannot be studied by the usual functional group analysis. A novel method for direct kinetic investigation of this reaction is presented and applied to a known low-polymeric polyethylene terephthalate free from monomer. During condensation polymerization the production of monomer is determined quantitatively through fractional vacuum sublimation. The contribution of reversible polycondensation to the monomer production is derived from the results of a previous kinetic study of the reversible polycondensation starting from the same precondensate. From the difference with the experimentally established monomer production, evaluation of the redistribution rate constant kr is possible. From the values of kr at 223 and 254°C. and activation energy of ?? 31 kcal./mole is calculated. At these temperatures kr is of the same order of magnitude as the rate constants of reversible polycondensation yet. At the normal manufacturing temperature of 280°C. redistribution proceeds considerably faster than polycondensation, thus rendering a rather quick restoration of a normal molecular size distribution if not present initially