| Greenization has become a significant research trend in the field of textile dyeing and finishing,which aims to eliminate the introduction of harmful substances and highrisk chemicals during the processes.Wrinkle-resistant finishing is a common type of functional treatment for cotton fabrics.However,formaldehyde-free wrinkle resistant chemicals and processes are still a challenge,and the research in this field has reached into a bottleneck.In this study,a novel approach was proposed to enhance the wrinkle resistance of cotton fabrics by employing oxidized sucrose as a non-formaldehyde crosslinking agent.A multifunctional aldehyde-based oxidized sucrose crosslinking agent was synthesized through the oxidation of sucrose using sodium periodate.The chemical structure,diffusion properties in fibers,and reaction characteristics with cellulose were systematically analyzed.Based on these findings,the finishing process was optimized to settle the insufficient wrinkle resistance issue as oxidized sucrose used as a crosslinking agent.The main findings were summarized as follows:(1)Aldehyde-based oxidized sucrose(OS)was prepared and its structure was analyzed by FTIR,MS,and NMR.It was found that OS existed in form of hydrates in aqueous solution and the solid state predominantly existed in intramolecular hemiacetal form(OSH).The hydrate structure of OS and the isomerization process leading to the formation of hemiacetals were confirmed by chemical calculations.(2)The diffusion behavior of OS in cotton fibers was investigated.It was found that the hydrate of OS in solution contained a significant amount of hydroxyl groups,which can form hydrogen bonds with cellulose and hinder the diffusion of OS into fibers.Traditional padding method was unable to make enough OS diffuse into the fibers,while the OS content of cotton fabrics treated with immersion pretreatment was much higher than that of fabrics treated with padding method.Molecular dynamics simulation showed that the diffusion of OS hydrates in fibers was lower than that of commonly used crosslinking agents such as BTCA,DMDHEU,glutaraldehyde,and ethylene glycol.The problem of low oxidized sucrose content in cotton fabrics was solved by immersion pretreatment.(3)The crosslinking reaction between OS and cellulose was investigated,and it was found that the hydrate structure of OS had a significant effect on the reaction.Situ infrared spectroscopy test showed that aldehyde hydrates that had not formed hemiacetals with cellulose had to undergo a dehydration process before participating in the crosslinking reaction during curing.Reaction kinetics analysis showed that the reaction between OS and cellulose was a pseudo-first-order reaction.And the activation energy was only 23.36 k J?mol-1 when aluminum chloride was used as a catalyst,which meant the reaction was relatively easily to carry out.Transition state theory calculations showed that the energy barrier for the formation of acetal from OS aldehydes and cellulose was higher than that of glutaraldehyde and ethylene glycol and required a stronger catalyst such as aluminum chloride for the crosslinking reaction.(4)Based on the analysis of the diffusion and crosslinking reaction processes,the effects of factors such as immersion pretreatment,OS concentration,catalyst,finishing liquid p H,curing temperature,and time on the wrinkle resistance of cotton fabrics were investigated and the process conditions were optimized by response surface methodology.The experimental results showed that immersion pretreatment significantly improved the wrinkle resistance of cotton fabrics.The wrinkle recovery angle of cotton fabrics by the finishing process with immersion pretreatment increased from 104.0° to 238.4°,with tensile strength retention rate of 52.12% and Hunter whiteness of 82.15.(5)The soundness of the structural analysis of OS and the hypothesis that intermolecular self-crosslinking of OS may occur after pre-impregnation treatment were validated by controlled experiment of oxidized sucralose.It was recommended to dry cotton fabrics in time after pre-impregnation to prevent self-crosslinking of OS which would stiffen the fabrics. |
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