Reactive Compatibilization of Poly(lactic acid) and Polycarbonate Blends Through Catalytic Transesterification Reactions

Abstract

The combination of poly(lactic acid) (PLA) with polycarbonate (PC) which presents high inherent thermal stability and mechanical properties is an attractive strategy to overcome PLA brittleness and poor thermal resistance. To improve affinity between the two materials and their dispersion into the blend, an organophilic montmorillonite (MMT) has been added and reactive compatibilization through catalyzed transesterification has been investigated. The properties were studied using differential scanning calorimetry (DSC), thermogravimetry (TG), dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). The study of the thermal properties revealed the immiscibility of the uncatalyzed blend but noticeable changes were detected on the PLA crystallization and melting behaviors after the addition of the catalyst. The SEM observations showed that MMT and the catalyst contribute in the improvement of the dispersion. The TG results revealed that MMT increases the thermal stability of the blend and showed new stages of decomposition due to the different structures resulting from the interchange reactions.

Compatibilization of Poly (lactic acid)/Polycarbonate Blends using Triacetin-mediated Interchange Reactions

“…The increase in the tensile properties is majorly due to the improved interface of the PLA/PC blends in the presence of TA-2022 compatibilizers. According to Melia et al [18], the addition of TA-2022 caused a transesterification reaction in the blends, which improved the mechanical properties by increasing compatibility.…”

“…Additionally, the size of PC droplets was measured to depict smaller dimensions in the range of 2-10 um. This dispersion may be due to the transesterification mechanism, thereby stabilizing the PC droplets from coalescing [18].…”

“…The usage of appropriate compatibilizer like triacetin is essential along with the catalyst to improve toughness by enhancing adhesion at the interface of PLA/PC blend [3]. The interfacial strength acts as a significant role in the performances of the polymer blends, and the enhanced strength can be stabilized for the stress transmission, which is found by the degree of interfacial polymer chains entanglement [17][18][19][20].…”