Study On Grafting Modification Of Cellulose And Properties

Cellulose is the most abundant natural polymer resources in the world, is the renewable resources of organic, it has a unique reaction activity and molecular characteristics, such as biodegradable, avirulent and harmless, safety, biocompatibility and hydrophilic. Cellulose grafting modification has become the research focus.Superabsorbent materials not only retain its own advantages, but also has a very excellent water absorption and retention performance, is a kind of new functional materials which has the performance of high machinability.In this paper, cellulose was used as raw materials, by means of the activated and solution treatment of cellulose to obtain the uniform solution. Using NaOH/urea/thiourea aqueous solution and1-butyl-3-methylinidazolium chloride ionic liquid as the reaction medium, cellulose/Acryl amide (AM)/butyl methacrylate (BMA) graft copolymer was synthesized through radical polymerization with K2S2O8as initiator, AM and BMA as monomers and N,N’-methylene bisacrylamide (MBA) as cross linker in homogenous solution. The effects of the graft copolymerization conditions, namely temperature, reaction period, and dosages of K2S2O8, AM, BMA and MBA on the grafting effect were investigated. Structure of the graft copolymer was characterized by means of FTIR, XRD, TGA/DTA and SEM etc.The properties of water absorption and retention was also discussed.The results showed that:After alkali treatment, Crystal structure changes of cellulose changed very obviously, crystalliniry and crystal size also decreased. NaOH/urea/thiourea aqueous solution is adopted as the solvent of cellulose, the best dissolving conditions were7%NaOH,6%thiourea,8%urea. The results also showed that under the optimum copolymerization conditions, m(cellulose):m(AM):m(BMA):m(K2S2O8):m(MBA)=1:4:2:0.05:0.006,65℃,2h, the grafting ratio could be up to87%, the grafting efficiency could be36%and the max water adsorption ratio of the cellulose/AM/BMA graft copolymer could reach583g/g. Using1-butyl-3-methylinidazolium chloride ionic liquid as the reaction medium, by orthogonal experiments, the results also showed the optimum conditions, m(cellulose):m(AM):m(BMA):m(K2S2O8):m(MBA)=1:2.5:2.5:0.06:0.005,65℃2h, the grafting ratio could be up to89%, the grafting efficiency could be38%and the max water adsorption ratio reached590g/g. The principle of dynamics for cellulose/AM/BMA graft copolymer was discussed in this paper, with calculate the activation energy under conventional synthetic method is29.931(KJ·mol-1), and the influence of monomers centreation, initiation agent and temperature on reaction speed.