Grafting maleic anhydride onto polycaprolactone: influence of processing

Maleic anhydride grafted poly(ε-caprolactone) (PCL-g-MA) was prepared by grafting MA on PCL using an internal mixer and by reactive extrusion using dycumil peroxide (DCP) as an initiator. Experimental design 2³ was used with the purpose of evaluating the most efficient reaction condition at higher reliability for grafting. PCL degradation was assessed by intrinsic viscosity and size exclusion chromatography (SEC), percentage of reacted maleic anhydride (%g-MA) was measured by titration. Results of PCL-g-MA were also characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric analyzes (TGA). In general, data presented differences in the applied processes, maleic anhydride concentration (C_MA) was more significant for higher grafting content during reactions taking place in the internal mixer whereas for the reactive extrusion the grafting level is dependent on the dicumyl peroxide concentration and reaction temperature ratio (C_DCP/TEMP) at higher temperatures. Comparing the employed processes, regardless the synthesis temperature, reactive extrusion was more efficient with higher grafting content, with maximum gains of 80% related to the same internal mixer formulation. Summing up PCL functionalization was effective and the use of PCL-g-MA as a compatibilizer is promising. (paper)