Biomass-based UV Light Grafting Of PAN Fabric And Its Flame Retardant Properties

Polyacrylonitrile(PAN)fiber is an important synthetic fibers,which plays a more important role in the textile industry,due to the good softness,resilience,fluffy warmth and other excellent properties,and has the good reputation of"artificial wool".Unfortunately,the limiting oxygen index(LOI)of PAN fiber is only 17%,which is one of the most flammable synthetic fibers.Therefore,the development of flame-retardant PAN fibers or fabrics becomes particularly important and attracts extensive attention of the academia and the industry.The aim of this paper is to introduce the biomass which is easy to be char-formed into the surface of PAN fabric based on the UV-induced grafting technology,and then the introduced biomass was phosphorylated to construct the intumescent coating on the surface of PAN fabric,so as to realize the high-efficiency flame retardant of PAN fabric.In the first part of this study,glycidyl methacrylate(GMA)was firstly grafted onto the surface of PAN fabric by UV-induced photo grafting polymerization to obtain the PAN-g-GMA fabric.Then,PAN-g-GMA was chemically grafted with chitosan(CS)to obtain the CS grafted PAN-g-GMA fabric(PAN-g-GMA/CS).Finally,the flame-retardant PAN fabric(FR-PAN)was prepared by phosphorylation of PAN-g-GMA/CS.The structure and elemental analysis of the flame-retardant PAN fabric were characterized by Fourier transform infrared spectroscopy(FTIR),scanning electron microscope(SEM)and X-ray photoelectron spectroscopy(XPS).The thermal degradation properties and combustion characteristics of the fabrics were accessed by thermogravimetric analysis(TGA),differential scanning calorimetry(DSC)and cone calorimeter(CC).The results showed that the onset thermal decomposition temperature of FR-PAN fabric is lower than that of the control sample due to the preferential degradation of the grafting groups.The combustion test indicated that the combustion rate of the FR-PAN fabric is significantly reduced,indicating an excellent flame-retardant property.The second part of this study was based on PAN-g-GMA fabric obtained from the first part.PAN-g-GMA/Arg fabric was obtained by the reaction of PAN-g-GMA fabric and L-arginine.Finally,PAN-g-GMA/Arg was phosphorylated with phosphorus acid catalyzed by urea to obtain flame-retardant PAN fabric(FR-PAN).The structure and elemental analysis of the samples were characterized by FTIR,SEM and XPS.The thermal stability properties and the flame retardant properties of the FR-PAN fabric were accessed by TGA,DSC and CC.The char residue of FR-PAN fabric is more than51 wt%at 800 ~oC,which indicates good char-forming performance and combustion performance.The flame retardant durability and mechanical properties of FR-PAN fabric were studied by LOI and universal strength machine.The results showed that the LOI of FR-PAN fabric was 34.7%,and it still reached 27%after 40 times of washing,which showed that FR-PAN fabric has durable flame retardancy.The breaking strength of FR-PAN fabric decreased by 12.9%compared with PAN fabric,but the elongation at break increased by 115.2%.