The Preparation And Properties Investigation Of Acidic Ion Exchange Fiber By Radiation-induced Grafting Of Styrene Onto PTFE

A novel strongly acidic ion exchange fiber has been prepared by radiation-induced grafting of styrene onto PTFE fiber using simultaneous irradiation technique followed by a sulfonation reaction .And a novel weakly acidic ion exchange fiber also has been prepared by radiation-induced grafting of acrylic acid onto PTFE fiber using simultaneous irradiation technique .Grafting was carried out at irradiation dose of 30KGy and dose rates of 0.375kGy/h at room temperature. The degrees of grafting of PTFE-graft-polystyrene fiers and PTFE-graft-acrylic acid fiers are 20—121% and 20-115%.The structure of sulfonated polytetrafluoroethylene (PTFE-graft-PSSA) fibers are confirmed by the IR spectrum. Styrene and sulfonic group have been onto the PTFE matrix. The effect of the monomer concentration on the degree of grafting is investigated .That is the degree of grafting increase linearly with monomer concentration .The diameters of polystyrene grafted(PTFE-graft-PS) fibers and PTFE-graft-PSSA fibers increase linearly with the degree of grafting .The break strength of PTFE-graft-PS fibers decrease with the increase of degree of grafting .When the degree of grafting is low, the break strength of PTFE-graft-PS fibers is higher than the original fiber' s .The crosslinking reagent can enhance the fibers' mechanical properties. The break strength of PTFE-graft-PSSA fibers decrease quickly and is 50 % of the grafted fiber' s. The ion exchange capacity and water uptake of strongly acidic ion exchange fiber are 1.5 3. 8mmol/g and 20—32%. The TGA results show that the grafted fibers and sulfonated fibers remain stable until 345℃ , 267℃ under N2 atmosphere and E are 270 KJ/mol , 194.98 KJ/mol. The grafted fibers and sulfonated fibers remain stable until 249 ℃ , 255 ℃ under O₂ atmosphere and E are 100KJ/mol , 191.50 KJ/mol . So, the thermal stability of strongly acdic ion exchange fiber is better.The structure of acrylic acid grafted(PTFE-graft-AAC) fibers fibers are confirmed by the IR spectrum. Acrylic acid have been onto the PTFE matrix. The effect of the monomer concentration on the degree of grafting is investigated. That is the degree ofgrafting increase linearly with monomer concentration . The break strength of PTFE-graft-AAC fibers decrease with the degree of grafting' increase . Ion exchange capacity and dissociation constant of weakly acdic ion exchange fibers are 2.4⁵.6mmol/g and 8.The TGA results show that the PTFE-graft-AAC fibers remain stable until 348°C under N2 atmosphere and remain stable until 312 °C under 02 atmosphere .