Non-isothermal depolymerisation kinetics of poly(ethylene oxide)

Abstract

The depolymerization of low molecular weight poly(ethylene oxide) (PEO) under mild conditions was studied using a linear temperature ramped non-isothermal technique and the results compared with those obtained from a conventional isothermal technique. The analysis of the non-isothermal kinetic (NIK) data was performed using an original computer program incorporating an algorithm that systematically minimizes the sum of the squares of the residuals between the experimental data and the calculated theoretical kinetic profile in order to extract the kinetic parameters. The results revealed that the depolymerization of PEO proceeds in accordance with the Ekenstam model and follows the Arrhenius equation over the temperature range of ca. 40 to 130C. The NIK analysis resulted in a two-dimensional convergence to produce a unique solution set for the kinetic parameters of E a = 89.4 kJ mol -1 and A = 9.6  10 6 h -1 . These data are consistent with the results obtained from the isothermal experiments. It is proposed that NIK analysis is a quick and reliable means of obtaining kinetic parameters relevant to lifetime predictions in polymers whose degradation behaviour can be considered to be close to ideal.

Synthesis of graft copolymers based on hyaluronan and poly(3-hydroxyalkanoates)

“…As can be seen from Figure S1, P(3HB) hydrolysis in acetic acid solution results in exponential decay of molecular weight with the time. Depolymerisation/degradation processes have been modelled as random scission of macromolecular chains for different types of polymers (Cran, Gray, Scheirs, & Bigger, 2011;Martens et al, 2011;Staggs, 2002). Kinetic data for P(3HB) hydrolysis are reported in Figure S1.…”