Preparation Of Bagasse Cellulose-based Foams And Enhanced By Microfibrillated Cellulose

Bagasse cellulose-based foam is a new environmentally friendly,non-toxic and degradable low-density porous material.It has a wide application prospect in the field of building insulation.However,the cellulose-based foam has the problems of poor strength,susceptible to metamorphosis,difficult to synthesize three-dimensional structure.In this paper,the self-made cellulose microfibril(MFC)was used as a Pickering foam stabilizer to bind to the surface of the A/W interface to prevent the coalescence,collapse and stabilization of the foam system.In addition,agar was chosen as the second liquid to retain bubbles,according to the "gel trapping technique",spreading of the particles on an air-water surface and subsequent gelling of the water phase,and the second liquid addition creates a network of particles within the bulk fluid because of the pendular bridges formed between particles..The main studies and results are as follows:The foam-forming method was used to prepare the cellulose-based foam porous material.The study found that the foam molding method is environmentally friendly,simple,low energy consumption,and can be successfully used in the preparation of cellulose-based foam porous materials.In this paper,the mechanism of fiber morphology and the effect of surfactants on the stability of wet foam were analyzed.It was found that the wide fiber length distribution favored the foaming performance of the foam liquid.The larger the polydispersity of the fiber,the smaller the bubble diameter of the wet foam.Based on the single factor experiment,the formation process of wet foam was designed by using the response surface method.The foam forming process was optimized and the influence of the pulp concentration,stirring rate and stirring time on the foamability and foam stability were evaluated.The optimal mixing conditions were as follows:the pulp concentration was about 1.5%,the stirring rate was 2000 rpm,and the stirring time was 15 min.At this time,the maximum volume of foam was 337 mL,and the maximum air content was 75%.In this study,microfibrillated cellulose were prepared through pre-mechanical beating process combined with enzymatic hydrolysis,then the high concentration beater was used.Bleached bagasse pulp with high content of hemicellulose was raw materials.xylanase was used to hydrolyze hemicellulose.The obtained product CXC-MFC was gelatinous,with an average fiber diameter of 140 nm,a diameter range of 30 to 240 nm,an average length of 2.66?m,and a length dimension of 0.7 to 6.5 ?m.Through analysis of FTIR,IC,XRD,it can be seen that CXC-MFC fiber composition and crystal structure did not change.The effects of pre-beating combined with xylanase pretreatment on the morphology of fiber and its mechanism were studied.Found that:1)pre-beating can significantly reduce the length and width of the fiber,from 1.70 mm,23.24 ?m were reduced to 1.17 mm and 16.57 ?m,respectively,and fine fiber content increased from 30%to 68%.The enzyme contact points of fiber were increased,which could effectively improved the effect of the enzyme.2)Xylanase hydrolysis preparation of MFC has high yield and low energy consumption.Xylanase only hydrolyzes hemicellulose,and the treatment may loosed cellulose,reduced beating time and energy consumption.This article describes the preparation of novel aqueous spongy foams that are composed of three-dimensionally distributed wood-fiber networks stabilized with nanofibrillate cellulose(NFC)and/or MFC.The free standing aqueous spongy foams were prepared with the entrapment of NFC and/or MFC-stabilized air-in-water(A/W)capillary foams using "gel trapping technique".The stability of spongy foams could be controlled by manipulating the volume fraction of NFC and/or MFC and a secondary liquid immiscible with the continuous phase of the NFC and/or MFC suspension.Possible morphology and mechanical distribution of NFC and/or MFC within spongy foams were verified with optical microscope,SEM,and functional load-bearing method.Owing to three-dimensionally dispersed wood-fiber structure,ultra-lightweight(0.01-0.06 g/cm3),high porosity(>90%),and microporous(10-80 ?m),the NFC and/or MFC reinforced spongy foams,improved compressional strength-vertical direction obviously,from 0.0 to more than 2.0 psi.The interaction between cellulose fibers in the presence of cationic polyacrylamide(CPAM)was analyzed by rheology as a function of polyelectrolyte concentration and charge density.The charge density of the CPAM was the most significant factor in how yield stress responded to CPAM concentration.These data are used to determine the contribution of different surface forces to the overall interaction,and develop an overarching mechanism for how the addition of CPAM changes interactions between cellulose fibers.The mode of yielding of the pulp suspensions is also discussed,to develop an understanding of the relationship between colloidal forces and the rheology of fiber suspensions.This study shows that CPAM strongly influences the rheological properties of a cellulose fiber suspension in water.Yield stress was found to peak at around 50%above the value for a pure cellulose suspension,while high gel point decreased to less than a quarter of the gel point for cellulose alone.