Study On Halogen-free Flame-retardant Modification And Performance Of Polyacrylonitrile Fabric Surface

Polyacrylonitrile（PAN）fiber is one of the most important synthetic fibers.It has a soft and fluffy feel,excellent heat preservation,light resistance and weather resistance.It is widely used in clothing,industry and other fields.However,PAN fibers are extremely flammable,and their limiting oxygen index（LOI）value is only about 17%.In addition,toxic gases,such as CO,HCN and acetonitrile are generated during the combustion process of PAN fibers.Meanwhile,traditional flame-retardant PAN fiber is usually spun from a copolymer of vinyl chloride or vinylidene chloride and acrylonitrile which contain a lot of halogens.As a result,the traditional flame-retardant PAN fibers or fabric always generate large amounts of toxic fume during the combustion,which causes air pollution and threatens people’s life and health.Therefore,the development of halogen-free flame-retardant PAN products is of great significance and has broad development prospects.In the first part of this paper,in order to improve the flame retardancy of PAN fabrics,a combination of UV-induced grafting polymerization and sol-gel technology was proposed.Firstly,glycidyl methacrylate（GMA）was grafted onto the surface of PAN fabric by UV-induced grafting polymerization,and then the grafted fabric（PAN-g-GMA）was ammoniated with hydrazine to prepare Am-PAN-g-GMA.Finally,the Am-PAN-g-GMA was treated with organic-inorganic hybrid silica sol to prepare FR-PAN.Fourier transform infrared（FTIR）,X-ray photoelectron spectroscopy（XPS）,Raman spectroscopy（Raman）,thermogravimetry analysis（TGA）,differential scanning calorimetry（DSC）,thermogravimetry infrared（TG-IR）and cone calorimetry（CC）were used to characterize the structure and the properties of different samples.The results showed that the FR-PAN had a char residue of 31.38 wt%at 800^oC under the air atmosphere,and its heat release rate（HRR）and smoke production rate（SPR）are significantly reduced.The fabric shows excellent flame retardancy.In the second part of this paper,UV-induced grafting polymerization and layer by layer self-assembly were used to improve the flame retardancy of PAN fabric.Firstly,acrylic acid（AA）was grafted onto the surface of PAN fabric by UV-induced grafting polymerization technology,imparting the PAN fabric a negative charge property.Then,PAN-g-AA fabric was treated with self-assembly systems containing 10 wt%vitamin B₁ derivative-thiamine pyrophosphate solution and 0.5 wt%sodium alginate solution as cationic and negative system respectively to fabricate FR-PAN fabric.X-ray diffraction（XRD）,FTIR,XPS and Raman were used to characterize the structure and element composition of the fabric before and after treatment.The thermal properties of the original fabric and the treated fabrics were analyzed by TGA,DSC and micro calorimetry（MCC）.The results showed that the FR-PAN had a char residue of 19.4 wt%at 800 ^oC under the air atmosphere,and its heat release capacity（HRC）,HRR and peak heat release rate（PHRR）are significantly reduced,and the fabric shows good flame retardant performance.