Functionalization of poly(butylene adipate-co-terephthalate) with itaconic anhydride through graft copolymerization

Poly(butylene adipate-co-terephthalate) (PBAT) was functionalised with itaconic anhydride (IA) via melt grafting in a batch mixer, initiated by dicumyl peroxide (DCP). It was found that the ratio of IA to DCP is critical to avoid undesired side reactions, such as crosslinking and chain scission. PBAT and other polyesters with low aliphatic hydrocarbon content are relatively unreactive toward radical graft modification, providing relatively low degree of grafting. Using 2 wt% IA and 1.2 wt% DCP gave the highest degree of grafting (1%), with little indication of crosslinking or chain scission. The complex reaction mechanism of grafting presents a clear competition between grafting, homopolymerization, crosslinking, and chain scission. Using non-isothermal kinetic modeling, it was shown that the reaction is not first order, and that models making this assumption leads to incorrect results. Using the Vyazovkin model-free method, the effective rate constant was predicted over a typical melt processing temperature range. Low reagent concentration resulted in the lowest effective rate constant, and it was shown that the activation energy changes with conversion and is also affected by reagent concentration.

Automated summary

In this study, poly(butylene adipate-co-terephthalate) (PBAT) was functionalised with itaconic anhydride (IA) via melt grafting. The ratio of IA to dicumyl peroxide (DCP) was found to be crucial for the reaction outcome, and low reagent concentration and conversion resulted in the lowest effective rate constant.