Engineering titanium carbide ultra-thin nanosheets for enhanced fire safety of intumescent flame retardant polylactic acid

As a biodegradable polymeric material, the polylactic acid (PLA) has broad applications resulting from its various advantages and unique characteristics. Nevertheless, the application of PLA in various fields is greatly limited by its high flammability. Our recent effort focuses on the manipulation of benzyldimethylhexadecylammonium chloride (HDBAC) modified titanium carbide (Ti3C2Tx) ultra-thin nanosheets which are then used to improve the fire safety of PLA composites filled with silicon microencapsulated ammonium polyphosphate (SiAPP). The flame retardant evaluation showed that when 2.0 wt% HDBAC modified Ti3C2Tx (HDBAC-Ti3C2Tx) and 13.0 wt% SiAPP were added, the LOI value was increased to 33.3%, and the UL-94 V-0 level was obtained, besides the peak heat release rate, total heat release, peak smoke production rate and total smoke release decreased by 49.8%, 31.9%, 60.3% and 52.7%, respectively. The barrier and catalytic effects of the modified Ti3C2Tx nanosheets together with the subsequently formed TiO2 and phosphorus-containing species forming intact expanded carbon layers and interrupting the combustion route are responsible for remarkably improving flame retardancy and suppressing toxic gases of PLA. This work provides a new approach for greatly reducing the fire hazard of PLA.