Making a Supertough Flame-Retardant Polylactide Compositethrough Reactive Blending with Ethylene-Acrylic Ester-Glycidyl Methacrylate Terpolymer and Addition ofAluminum Hypophosphite

摘要

Biocompatible and biodegradable polylactide (PLA) composites with supertough mechanical property and sufficient flame retardancy were fabricated by employing a facile approach involving reactive blending of PLA and ethylene-acrylic ester-glycidyl methacrylate terpolymer (EGMA), with the addition of aluminum hypophosphite (AHP) as an effective flame retardant. In consideration of the balance between mechanical property and flame retardancy, the optimal formula was taking a PLA/EGMA 80/20 blend (supertough STPLA) as the matrix and adding 20 wt % of AHP (relative to the mass of STPLA) as the flame retardant, coded as STPLA/20AHP. The mechanical property test showed that for STPLA/20AHP the elongation at break was increased by about 22 times and the notched Izod impact strength was enhanced by approximately 11 times as compared to those for neat PLA. The flame-retardant property test showed that for STPLA/20AHP the limiting oxygen index value reached 26.6% and the UL-94 V0 rating test was passed. Thermogravimetric analysis, microscale combustion calorimetry, and cone calorimeter were further appliedto reveal the thermal stability and combustion behaviors of STPLA/xAHP, respectively, where x indicated themass content of AHP in percentage. The phase separation morphology,dispersion of AHP particles in STPLA matrix, and fracture surfacesand char residues after flame burning were examined by phase contrastoptical microscopy and scanning electron microscopy, respectively,which helped comprehend the results obtained from the mechanical propertyand flame retardancy tests. The supertough STPLA/xAHP, with sufficient flame retardancy as prepared in this work, couldhave a potential for engineering applications.