Thermal degradation studies of poly(trimethylene carbonate) blends with either polylactide or polycaprolactone

The thermal stability and degradation kinetics of poly(trimethylene carbonate) (PTMC) blends with different ratios of polylactide (PLA) and alternatively polycaprolactone (PCL) were investigated by thermogravimetric analysis under a nitrogen atmosphere. These studies were extended to the single components (i.e. PCL and PLA). In all cases, the derivative thermogravimetric curves indicated a complex decomposition process with at least two degradation steps. The kinetic parameters of the main step, including activation energy, reaction model and pre-exponential factor, were evaluated by the Kissinger, isoconversional (Friedman and KAS) and Coats–Redfern methods. Data of the main decomposition process were obtained by mathematical deconvolution of experimental DTG curves acquired at heating rates ranging from 2 to 40 °C/min.It was demonstrated that degradation of blends did not correspond to a mere superposition of the characteristic decomposition processes of the two involved polymers. Furthermore, PCL and PLA influenced the decomposition of the less thermally stable PTMC component in a different way. Thus, PLA modified the degradation of PTMC, and specifically led to thermal stabilization and a new decomposition process characterized by a higher activation energy. On the other hand, PCL favored the degradation of PTMC by enhancing a typical minor decomposition process that occurred in the single component at a lower temperature.The main decomposition step of PTMC, PLA, PCL and the studied blends always followed an Avrami model but with significant differences in their exponents (i.e. from 2 to 7).

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Non-isothermal degradation kinetics of polylactide and polycaprolactone. ► Degradation behavior of copolymers of trimethylene carbonate and lactide. ► Degradation mechanism of blends of poly(trimethylene carbonate) and polylactide. ► Degradation behavior of blends of poly(trimethylene carbonate) and polycaprolactone.