Shape Collapse of Thick-walled Polylactic Acid Mouldings with Metal Hydroxide Flame Retardants in Industrial Compost

Abstract

An effect of metal hydroxide-based flame retardants on shape collapse of thick-walled mouldings in an industrial composting environment was evaluated for polylactic acid (PLA) composites. PLA composites with 30 wt% aluminium hydroxide (Al(OH)₃) and magnesium hydroxide (Mg(OH)₂), selected as flame retardants, were prepared and PLA and PLA composite specimens (t = 4 mm) were produced by injection moulding. These specimens were buried in an industrial compost environment for 60 days and evaluated for changes in the shape and mass of the specimens. The shape collapse of the PLA composites with 30wt% Al(OH)₃ was less than comparable to neat PLA, which split to the cm scale and lost 14% of its mass in 60 days. PLA composites with 30wt% Mg(OH)₂ added fined and reduced in mass by 55% in 7 days and by 84% in 60 days. Therefore, the addition of Mg(OH)₂ in PLA composites accelerated the shape collapse of thick-walled moulds in industrial compost.