Study On The Preparation Of Nanofibrillated Cellulose By High-pressure Fluidization And The Properties Of Disperse Organic Dyes

Nanofibrillated cellulose(NFC)has the characteristics of high strength,high crystallinity,reproducibility,good biocompatibility and biodegradability.So it has a broad application prospect in material reinforcement,drug carriers and particle dispersion.The application research of NFC in the field of particle dispersion is not comprehensive enough.Therefore,this paper mainly studies the structure and performance characteristics of different NFC,and explores the effect of different NFC on the dispersion performance of organic dyes.In this thesis,the influences of different homogenization pressure and homogenization cycles on the structures and properties of NFC products were studied,and the bleached wood pulp fibers were pretreated by biological enzymolysis-mechanical fine grinding.The results showed that with the increase of the homogenization pressure and homogenization cycles,the surface morphology of the NFC was changed obviously,the fiber length and particle size of fiber was decreased continuously,and there was a phenomenon of fiber agglomeration.Scanning electron microscopy showed that the wood pulp fiber was completely cut under the condition of homogeneous 20 times at a pressure of 25,000 psi.It was found that the fiber had reached the nanometer diameter and the diameter was about 67 nm.In addition,the stability of NFC dispersion was improved gradually,the crystallinity was increased first and then decreased.In order to introduce a hydrophobic structure into the prepared nano-microfibrillated cellulose,the dispersion and stabilizing ability of NFC to hydrophobic substances was enhanced.In this thesis,unbleached coniferous wood pulp was used as raw material to prepare lignin-containing nanofibrillated cellulose(LNFC)by biological enzymolysis-mechanical fine grinding combined with high-pressure homogenization.The effect of homogenization pressure,homogenization cycles and lignin-containing on the properties of LNFC was analyzed.The results showed that the surface morphology changed process of LNFC was similar to the surface morphology changed process of NFC,but the surface morphology change process of LNFC had a certain lag.The possible reason is that the presence of lignin can delay the process of fiber microfibrinization in the low-pressure process,which ultimately can promote the process of fiber microfibrinization in the process of high pressure homogenization.With the increase of homogenization pressure and homogenization cycles,the agglomeration of LNFC is not obvious and the homogeneity is high.The average fiber particle size of LNFC fiber was increased first and then decreased.In addition,the dispersion stability of LNFC maintained an upward trend,and the dispersion stability of microfibrinolytic cellulose containing lignin was better than that of microfibrinolytic cellulose prepared under the same conditions.Finally,the effect of different nanofibrillated cellulose on the dispersibility of organic dyes was studied.With the increase of homogenization pressure and homogenization cycles,the dispersion stability of NFC and LNFC was improved,and the dispersion stability of organic disperse orange 30 dyes by NFC and LNFC was improved.In the organic disperse orange 30 dyes,NFC and LNFC were added respectively.With the continuous increase of the added amount of NFC and LNFC,the dispersion stability of the organic dispersing orange 30 dyes was increased first and then decreased.When the added amount of NFC and LNFC was 20%,the dispersion stability was the best.In addition,the effects of different characteristics of nanofibrillated cellulose on the dispersion stability of organic disperse orange 30 were ranked as follows: Lignin-containing Nanofibrillated cellulose(LNFC)>Nanofibrillated cellulose(NFC)>Tempo oxidation NFC(TONFC)> Cellulose Nano Crystals(CNC)> Tempo oxidation NFC6(TONFC6).