Study On Grafting Modification Of Superfine Fiber Synthetic Leather Base By Collagen With Different Cross Linkers

Superfine fiber synthetic leather has become a research hotspot recently due to its wide raw materials source and excellent mechanical strength.However,the superfine fiber synthetic leather base(SFSLB)has less active groups,which makes it impossible to absorb and transfer water vapor between fibers and the outside environment,thus causing the poor sanitary performance of SFSLB.In this study,collagen was used as modifier,which was extracted from leather waste and contained lots of active groups.Through chemical cross-linking method,collagen was grafted onto the SFSLB by different cross linkers to improve the sanitary property of SFSLB,which can reduce environmental pollution and realize reasonable utilization of leather waste.The SFSLB was modified by using collagen as modifier and oxazolidine(a kind of aldehyde compounds)as cross linker,respectively.The water vapor permeability,hygroscopicity and grafting rate of collagen were used as indexes.The optimimum modification condition was obtained by single factor experiment and orthogonal experiment.The results were as follows:collagen dosage was 13%(basing on the weight of dry base),oxazolidine dosage was 7%,the modification temperature was 40?,crosslinking reaction time was 95min,the reaction time of collagen was 105min.The water vapor permeability,moisture absorption and mechanical strength of the modified base were characterized.Results revealed that the water vapor permeability,moisture absorption,tensile strength,tear strength of midified base increased by 31.80%,29.92%,9.04%,33.02%,respectively compared with pristine base.The modified base was also characterized by FT-IR,SEM,contact angle,and so on.The results showed that the characteristic peaks of carboxyl groups on the base appeared after being modified by collagen.Besides,the fiber dispersion increased,and the contact angle became smaller.The SFSLB was modified by using collagen as modifier and urea formaldehyde resin(UF,a kind of hydroxymethyl cross linker)as cross linker.The optimimum modification conditions was obtained by single factor experiment and orthogonal experiment.The results were as follows:collagen dosage was 9%,UF dosage was 9%,the reaction temperature was 47?,the crosslinking reaction time was 135min,the reaction time of collagen was 180min,and pH was 4.The water vapor permeability,moisture absorption and mechanical strength of the modified base were characterized.Results revealed that the water vapor permeability,moisture absorption,tensile strength,tear strength of midified base increased by 52.99%,33.80%,29.82%,70.51%,respectively compared with pristine base.The modified base was characterized by FT-IR,XPS and XRD.The results showed that characteristic peaks of carboxyl groups on the base appeared after the modification by collagen,what's more,the contents of C,N,and O increased,the crystallinity decreased by collagen treatment.The SFSLB was modified by using collagen as modifier and epoxy resin was as cross linker.The optimimum modification conditions were obtained by single factor experiment and orthogonal experiment.The results were as follows:collagen dosage was 13%,the amount of epoxy resin was 11%,reaction temperature was 3 8?,crosslinking reaction time was 150min,the reaction time of collagen was 105min.The water vapor permeability,moisture absorption and mechanical strength of the modified base were characterized.The results suggested that the water vapor permeability,the moisture absorption,tensile strength,and tear strength of midified base increased by 43.00%,31.86%,8.99%,13.45%,respectively compared with pristine base.The modified base was characterized by FT-IR,SEM,AFM,and so on.the results showed that the modified base appeared carboxyl groups and a small amount of epoxy groups,fiber became looser,and the surface roughness increased firstly and then decreased.These changes confirmed that the modification of the base achieved remarkable results.DSC and TG were used to investigate the thermal stability of the modified bases.It was showed that the thermal stability of the base was significantly improved,and the base crosslinked by epoxy resin had the best performance among them.The formaldehyde content of modified bases was investigated.The results indicated that the formaldehyde content of the base crosslinked by oxazolidine,UF and epoxy resin were llmg/kg and 3.06mg/kg,Omg/kg,respectively.The grafting percent,water vapor permeability and hygroscopicity of three modified bases were also compared.The above results revealed that epoxy resin had the best modification effect.