Jordan D’AMARIO, Wanwarang LIMSUKON, Anibal BHER, Rafael AURAS
The biodegradation performance of non-pretreated and pretreated commercial polyesters was evaluated under simulated composting conditions to understand how abiotic pretreatment accelerates biotic degradation. Polylactic acid (PLA) and polycaprolactone (PCL) were subjected to hydrolysis pretreatment and assessed under simulated composting conditions for 120 days. In addition to tracking CO2 evolution, polymer-intrinsic factors such as chain scission, measured by reductions in intrinsic viscosity molecular weight (𝑀𝜂), and changes in crystallinity (Xc) were also evaluated for both non-pretreated and pretreated samples during the biodegradation process. Hydrolysis pretreatment resulted in a reduction of initial 𝑀𝜂 and an increase of initial Xc for all polymer samples. The initial decrease in 𝑀𝜂 was particularly marked for PLA, which showed about 30% decrease, while PCL exhibited a reduction of just around 7%. Regarding initial Xc, the most significant increase was also seen in PLA, which jumped from approximately 0% to c. 30%. Hydrolysis of semi-crystalline polymers primarily affects the amorphous region, where elevated temperatures allow water to break polymer chains easily. However, for PLA, the disruption of the crystalline structure leads to a less stable type of crystal, probably due to an increase in the rigid amorphous region that enhances the overall biodegradation process. The effect of pretreatment on the biotic phase showed minimal differences for PCL but a noticeable overall increase in biodegradation for the pretreated PLA.