Jute woven fabric modified by phosphorus-containing organosilicon compound reinforced flame retardant polylactic acid composites with enhanced flame retardant and mechanical properties

Balancing the flame retardant properties and mechanical performance is important for flame retardant composites. In this research, the polylactic acid (PLA)/fiber composite is prepared by treating jute woven fabric with phosphorus-containing organosilicon compound (PCOC) and adding intumescent flame retardant (IFR) to PLA using a film-stacking procedure, which is named flame retardant PLA (FRPLA)/PC-F. The flame retardancy and mechanical properties of PLA/fiber composites were studied and analyzed. Mechanical/flame retardant index (M/F index) was developed to compare the comprehensive properties of the composites. The limited oxygen index (LOI) test results show the LOI value of FRPLA/PC-F reaches 34.1%, 14.1% higher than untreated PLA/fiber composite (PLA/F). In the cone calorimeter test, the pk-heat release rate (HRR) value of FRLA/PC-F decreases from 549 to 388 kW/m(2) compared with PLA/F. In addition, the char yield of FRPLA/PC-F increases from 1.9% (PLA/F) to 18.6%. The scanning electron microscope images of the char yield for FRPLA/PC-F obtained from cone calorimetry test shows a continuous network structure with the fibrous skeleton completely wrapping by the dense and uniform char layer, which plays a barrier effect that inhibits the release of volatile substance and the transfer of heat. Meanwhile, FRPLA/PC-F exhibits 28% and 19% improvement in tensile strength and impact strength compared with PLA/F due to the boost of interfacial adhesion between fiber and PLA. The M/F index of FRPLA/PC-F is 1.15, which is the highest among all the composites, proving the best comprehensive properties and practical applicability. The results in this manuscript above make a great development, which is attractive in the design of PLA/fiber composites with great comprehensive performance.