Fabrication Of Durable Flame Retardant Polyacrylonitrile Fabric Based On Ultraviolet Light Grafting

Fire has seriously threatened the safty of people’s lives and property,and textiles are the most imflammable materials to cause fire easily.PAN fibers and their textiles are widely used in the fields of clothing,decoration and other applications due to their excellent properties.However,the LOI of PAN fiber is only 17-18.5%,indicating that they are easily to bum and cause fire.Therefore,it is of great significance to prepare flame retardant polyacrylonitrile fiber with low cost and high efficiency.In the first part of this study,the one-step UV-induced grafting technology was used to prepare PAN-g-GMA fabric,and the active epoxy group was introduced onto PAN fabric.The effects of photoinitiaor concentration,monomer concentration,temperature,irradiation time and irradiation distance on GMA contents were discussed.The results showed that the grafting rate increased with the increase of monomer concentration,the increase of temperature,the increase of irradiation time and the decrease of irradiation distance.GMA content shows a rule of increase rapidly and then falls down with the increase of BP concentration.The optimum process of grafting was obtained.The PAN fabric and PAN-g-GMA fabric were characterized by FTIR,XPS,XRD,SEM and TG.In addition,the values of LOI were also tested.Compared with the PAN fabric,the characteristic absorption peak of epoxy group appeared in the FTIR spectrum of PAN-g-GMA fabric.The ratio of O/C increased significantly,and the surface of fibers became rough,which indicated that GMA had been successfully grafted onto the fabric.After grafting,The XRD pattern of PAN-g-GMA fabric is the same as that of the PAN fabric,there is no additional diffraction peak appears,and the intensity of the diffraction peak changes,suggesting that the crystal structure was not destroied by grafting.The initial decomposition temperature of the PAN-g-GMA fabric is lower than that of PAN fabric,the residual weight decreased from 38%to 25%,and the value of LOI decreased.All of these resulted from the instability of GMA chain.In the second part of the study,the PAN-g-GMA fabric(with a GMA mass fraction of 47 wt%)was chemically modified by ethylenediamine and phosphoric acid.The FR-PAN fabric was obtained by introducing the flame retardant elements nitrogen and phosphorus.FTIR,XPS,XRD,SEM,TG and CC were used to analyze and characterize the products obtained in different stages of chemical modification,and the residue of FR-PAN fabric was researched by SEM.Compared with PAN-g-GMA fabric,the FTIR spectrum of PAN-g-GMA/ED fabric showed that the characteristic peaks of epoxy groups disappeared and the characteristic absorption peaks of hydroxyl and amine groups appeared.The content of nitrogen increased,and the coarse particles on the surface became smooth and small,indicating that the epoxy group reacted with ethylenediamine.There was no significant change in XRD pattern,which illustrated that the crystal structure was not destroyed by the amination.The residue weight of PAN-g-GMA/ED fabric was reduced to 23%,and the flame retardancy was not improved.Compared with PAN-g-GMA/ED fabric,the stretching vibration peak of O-P-O appeared in the FTIR spectrum of FR-PAN fabric.The characteristic absorption peak of P2p appeared on the XPS spectrum,and the surface morphology of fiber changed,which indicated that phosphorylation occurred.The diffraction peak in the XRD pattern is weakened,indicating that the phosphorylation treatment reduced the crystallinity of the fabric.In addition,the residue weight of FR-PAN fabric was 25%and was a little higher than that of the PAN-g-GMA/ED fabric.Cone calorimeter test results showed that the heat release rate(HRR),the total heat release(THR),the smoke production rate(SPR)and the total smoke production(TSP)of FR-PAN fabric largely decreased.The LOI value was also increased,and the flame-retardant effect was still remained after 50 times washing,which indicated that the prepared FR-PAN fabric had durable flame retardancy.In addition,SEM was used to analysis the residual char of FR-PAN fabric.In this paper,a durable flame retardant polyacrylonitrile fabric was prepared through introducing nitrogen and phosphorous into the fabric surface by the combination of UV grafted technology and chemical modification,which develops a novel flame retardant method for PAN fibers or fabrics,and will be of great significance for the promotion of the differentiation of polyacrylonitrile fibers.