Synthesis and characterization of poly (Lactic Acid) plasticized palm oil phosphate ester

Abstract

This study focusing on the synthesis of epoxidized palm oil (EPO) containing flame retardant group, palm oil phosphate ester (POPE) into poly (lactic acid) (PLA) by using melt blending technique. POPE was synthesized by reacting EPO and diethyl phosphate as flame retardant catalyzed by triphenyl phosphine. The effect on variation of catalyst concentration, time and temperature on the yield of synthesized POPE were studied. Triphenyl phosphine acted as a catalyst was varied at the amount of 0.1, 0.2, 0.3 and 0.4 g while temperature ranging from 70, 80, 90 and 100 °C and 1 to 5 h for time variation. Then, PLA was mixed at various amount of POPE. The optimum formulation on POPE was determined by varying the content of POPE from 1 to 5 wt% into the PLA to produce good mechanical and flame retardant properties. Characterizations of POPE and PLA/POPE blends were conducted by using Fourier transform infrared spectroscopy. The samples of PLA/POPE were studied by using tensile test, flexural test and impact test to determine their mechanical properties. While thermogravimetric analysis and differential scanning calorimetry were performed to analyze thermal characteristics of the blends. Limiting oxygen index (LOI) test was conducted to determine the flammability properties of PLA/POPE blends. Finally, the surface of PLA/POPE samples before and after LOI test were investigated by using scanning electron microscopy for morphological study. The optimal reaction for POPE was achieved at 0.2 g catalyst, 80 °C temperature for the reaction time of 4 h. In general, the addition of POPE into PLA reduced the mechanical properties such as stiffness and tensile strength. On the other hand, it increased an elongation at break. Moreover it was observed that the thermal stability of PLA/POPE blend increased by incorporating POPE. Besides that, the incorporation of POPE into PLA improved the flammability properties of the PLA/POPE blend with LOI value of 30. The morphological studies revealed that the maximum amount of POPE which could be well dispersed was at 1 wt% of POPE. Based on the results obtained, the optimum loading in terms of mechanical and flammability properties for POPE incorporating with PLA was at 1 wt%.