Combination effects of a bio-based fire retardant and functionalized graphene oxide on a fire retardant and mechanical properties of polylactide

The intrinsic brittleness and flammability of polylactide (PLA) hamper its further application in the industrial and civil fields. Aiming at this point, a bio-derived core-shell flame retardant (CSFR) was applied to improve the flame retardancy of PLA under the condition of maintaining the environmentally friendly profile of this bio-based polymer in this work. However, the enhancing effect of the CSFR on the mechanical properties of PLA was quite limited, and even a deteriorating effect was found on its rigidity. Therefore, functionalized graphene oxide (GO) was utilized through the masterbatch method, which improved not only the flame retardancy but also the mechanical properties such as modulus and impact toughness. The data showed that the combined effect of the CSFR and GO could facilitate to fabricate the flame retardant PLA with better thermal and mechanical properties. PLA/GO-3/4%CSFR got the highest notched impact strength (11.29 kJ/m2), better Young's modulus (4.1 GPa), and improved elongation at break (7.5%). Through the analysis of condensed and gas phase products, it was found that the CSFR and GO performed their function by the condensed-phase flame retardant mechanism.