Multiwalled carbon nanotubes and sepiolite nanoclays as flame retardants for polylactide and its natural fibre reinforced composites

This work aims to develop a fully bio-based polylactic acid (PLA) composite with improved flame retardancy, utilising the unique properties of sepiolite nanoclay (Sep) and multiwalled nanotubes (MWNT). The pyrolysis combustion flow calorimeter (PCFC) also known as the microcalorimeter was used to screen the various PLA nanocomposites with respect to their potential flammability performance. The heat release capacity (HRC) which is an indicator of a materials fire hazard, reduced by 58% for the PLA ternary system based on sepiolite and MWNTs. Thermal gravimetric analysis (TGA) showed significant improvements to the residual char towards the later stages of the thermal ramp. The PLA ternary nanocomposite showed a 45% reduction in peak heat release (PHRR) when tested in the cone calorimeter. A further noteworthy observation was the 25% reduction in PHRR upon the introduction of hemp fibre into the PLA nanocomposite system.