Preparation And Properties Of A New Flame Retardant Polyacrylonitrile Fabric Containing Phosphorus And Nitrogen Elements

With excellent properties such as softness,warmth,resilience,and resistance to mildew,polyacrylonitrile(PAN)fibers were widely used in the decoration and textile industries.However,the extreme oxygen index(LOI)value of PAN fiber was only 17.5%,which has a high fire hazard.The PAN fiber and its fabric need to be treated with flame retardant.Firstly,the thesis analyzes and evaluates the combustion characteristics of PAN fabrics.Then,PAN fabrics were treated with the physical coating method and the chemical grafting method for flame retardancy,respectively.The optimum process parameters were obtained,and the corresponding flame retardant mechanism was analyzed.The main research contents are as follows.1.Pure PAN fabric was used as raw material to study its thermal stability,combustion characteristics,smoke production characteristics and pyrolysis behavior,and its fire hazard was evaluated and analyzed.Studies have shown that increasing the thermal radiation intensity(25k W/m² to 50 k W/m²),its ignition time was shortened from 10 s to 4 s,the thermal release rate peak increased by 55.8%and the smoke production rate peak increased by 107.4%.2.Ammonium dihydrogen phosphate hybrid silica sols were prepared from ethyl orthosilicate(TEOS),water,anhydrous ethanol,and ammonium dihydrogen phosphate(NH₄H₂PO₄).P-N-Si PAN fabrics were finished by impregnation,drying,and roasting.The study showed that P-N-Si PAN fabric surface was successfully attached with phosphorus-nitride silicon coating.The high-temperature thermal stability of P-N-Si PAN fabric was significantly improved,the flame retardant grade was upgraded to V-0,the LOI value was increased from17.5%to 24.6%,and the total heat release and total smoke production were reduced by 42.5%and 30.9%,respectively.This was mainly because the P-N-Si PAN fabric in the combustion process generated by phosphorus-containing radicals to inhibit the combustion chain reaction;Si-containing compounds generated by thermal decomposition of Si O₂,P-containing compounds generated by the heat of polyphosphoric acid-like substances catalyzed the formation of dense carbon layer structure together to play a solid-phase flame retardant effect.Compared to PAN,P-N-Si PAN fabrics showed a 125%increase in Fire Performance Index(FPI)and it showed a 44%decrease in Fire Growth Index(FGI).3.FRPAN fabrics were obtained using hydroxylamine hydrochloride(HA)and phytic acid(PA)treatment.Research shows that FRPAN fabric molecular chain was successfully introduced with flame retardant P and N elements.FRPAN fabric thermal stability in the high temperature region was significantly improved,the flame retardant grade was upgraded to V-0,and the LOI value was increased from 17.5%to 33.6%,and the total heat release and total smoke production decreased by 39.4%and 69.1%,respectively.This is mainly due to FRPAN fabric pyrolysis generated by NH₃ and other flame-retardant gas dilution and phosphorus-containing radicals to capture H·and OH·radicals to inhibit combustion reactions;the catalytic carbon formation of polyphosphoric acid-like substances produced in the solid phase formed a stable and dense carbon layer structure,which played a role in flame retardancy.Compared with PAN,FRPAN fabric showed a 113%increase in FPI and it showed a 60%decrease in FGI.