Study of biodegradable poly(butylene succinate-co-adipate) (PBSA) maleation: Analysis of grafting, thermal, and rheological behaviour

Abstract

Herein, the effects of varied concentrations of an organic peroxide and maleic anhydride (MA) on the grafting percentage as well as the amount of gel content, rheological, and thermal properties of MA-grafted-poly(butylene succinate-co-adipate) (PBSA) were analyzed. The grafting was performed by melt extrusion processing. The MA grafting onto the PBSA polymer chains was successfully confirmed through Fourier transform infrared spectroscopy, and the MA-grafting percentage was quantified by the back titration. Increasing MA and initiator content increased the peak intensity (at 1780 cm−1) associated with grafted saturated anhydride MA moieties on the PBSA backbone. Higher concentrations of initiator and MA directly influenced the grafting percentage, reaching to the maximum grafting degree of 2.48%. A greater amount of initiator produced more radicals on the polymer chain, promoting crosslinking reactions, resulting in a higher gel content and complex viscosity. This increased gel content and, thus, higher complex viscosity. Additionally, the increase in gel content affected the thermal stability of the MA-grafted-PBSA where the maximum decomposition temperature was increased by ⁓7°C, as a result of the improved crosslinking effect. Higher MA grafting percentage reduced the chain regularity of maleic anhydride grafted PBSA (MA-g-PBSA); therefore, the percentage crystallinity decreased. Gaining insight into the impact of MA and initiator concentrations on MA-grafted-PBSA can aid in developing composites or blends with enhanced miscibility and performance.