Preparation Of Fire-retardant Bamboo Activated Carbon/study On Polylactic Acid Composite

With the increasing awareness of environmental protection,the "anti-plastic" trend has emerged and polymer materials are gradually moving towards biodegradable directions.Polylactic acid(PLA)is widely used in various fields of life due to its excellent comprehensive performance.However,due to the inherent flammability of PLA,there is a great risk of fire during use.Therefore,it is essential to improve the flame retardancy of PLA.In this study,bamboo charcoal was used as the raw material,and bamboo-derived activated carbon(BAC)prepared by steam activation was utilized as both a flame retardant carrier and synergist in the flame retardant system,to improve the flame retardancy of PLA.The mechanism of the flame retardant system was investigated to provide basic research for the application of BAC in the field of flame retardancy.The following research results were mainly obtained:(1)Based on the rich pore structure and oxygen-containing functional groups of BAC after steam activation,high-phosphorous phytic acid was used to modify BAC,and the phosphorus-containing flame retardant bamboo-derived activated carbon(PBAC)was prepared.The structure of PBAC was analyzed by Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM)and thermogravimetric(TG)testing.Whereafter,PLA composites with different amounts of PBAC were prepared.The addition of PBAC significantly improved the flame retardancy of the composite materials.When the content of PBAC was 12 Wt.%,the oxygen index(LOI)of the material reached 31.8 vol%.And when the content of PBAC was 18 Wt.%,the LOI value was as high as 33.6 vol%,which was much higher than the LOI value of pure PLA(20.1 vol%).Moreover,all materials with PBAC contents higher than 12 Wt.% achieved a V-0 rating,with the combustion of the materials being significantly restricted.Both the peak heat release rate(HRR)and total heat release(THR)of PLA/PBAC materials were reduced.(2)Bio-sourced phosphoric acid and urea were selected as modifiers to design and prepare phosphorus/nitrogen-doped flame retardant BAC named BACm,with the aim of further reducing the amount of flame retardant added,improving the flame retardancy of the material,and avoiding loss of mechanical properties.The analysis showed that BACm could enhance the flame retardancy of PLA and improve the stiffness of the material.Compared with only phosphorus-modified materials,the flame retardant effect of BACm was further improved.By adding 9 Wt.% BACm,the composite material can reach the V-0 rating,with an LOI value of 31.7 vol%.Cone calorimeter showed that as the flame retardant filler increased,the HRR and THR of the composite material decreased while the char residue increased significantly,and SEM revealed that the char residue gradually became more intact and dense.(3)By utilizing the high adsorption performance of BAC and the catalytic synergistic effect of metal oxides during flame retardant combustion,ZnO and CuO were loaded onto BAC by solvent evaporation to prepare bamboo-derived activated carbon@ metal oxide(BAC@MO).BAC@MO was modified with phytic acid/urea and phosphoric acid/urea to obtain PBACm@MO and BACm@MO for modifying PLA.The results showed that the addition of metal oxides improved the flame retardancy and char-forming ability of the composite materials.BACm@MO was found to be more effective than PBACm@MO,and ZnO showed better synergistic effects than CuO.