Chemical Recycling of Poly (L-lactic acid) Compounds Contained with Aluminum Hydroxide Type Flame Retardant using with a Twin Screw Extruder

Abstract

For the chemical recycling of poly (L-lactic acid) (PLLA) component in fire-resistant polymer alloys used for electric/electronic equipments, effects of Al(OH)₃ added as a flame retardant on the thermal depolymerization of PLLA component were evaluated. As a result of examining the conversion from the PLLA/PP/Al(OH)₃ [14/56/30(wt/wt/wt)] compounds to lactide monomer, L, L-lactide purity of 90% was achieved under the recovery ratio of about 90%. Furthermore, the combination of Al(OH)₃ and MgO accelerated PLLA depolymerization as synergetic catalyst to generate L, L-lactide. This study used with a practical twin screw extruder is the first achievement as an efficient chemical recycling system to obtain lactide monomer recovery from PLLA compounds.