Study On The Preparation And Properties Of Microfi-brillated Cellulose From Soybean Residue

Soybean residue(SR),an agricultural waste,is produced during the processing of soybean products.It is very huge,low cost and renewable.At present,only a small part of SR is used to the food consumption,most of them are used for the feed or are abandoned directly,which has caused a great waste of resources and environmental pollution.The technology of MFC preparation from SR was studied by chemical pretreatment and mechanical treatment.The preparation process,structure and properties of soybean residue MFC were obtained.In order to promote the high value and resource utilization of soybean residue,the feasibility of preparing MFC by deep eutectic solvents and the application of MFC on edible packaging film were preliminarily discussed.The raw materials of MFC preparation was ebriched and the application field of SR was widened.At the same time,it provides a theoretical basis for the research of SR in nanocellulose.The pretreatment process of degreasing and deproteinized was studied.The optimal technology parameters was obtained by the single factor experiment as follow: the addition of lipase and protease is 375 U/g?1500 U/g,respectively,reaction time is 2 hours.Under the conditions,the removal rate of fat and protein is 75%?70%,respectively.The effect of acid and alkali pretreatment on the preparation of MFC was discussed.The characteristics of SR after acid pretreatment and alkali pretreatment were studied by XRD,TG-DSC thermal analyzer,specific surface area and porosity analysis.The difference of fiber surface morphology and characteristics of SR during different pretreatment stages were revealed.The results showed that the characteristic groups of the cellulose were not affected by the acid and alkali pretreatment.The non cellulose substances was effectively removed by the acid and alkali pretreatment,resulting in the decrease of amorphous content and the increase of crystallinity.Compared with alkali treatment,the specific surface area,porosity,crystallinity and thermal stability of SR increased after acid treatment.It is showed that the non-cellulose decrease,the structure becomes loose after acid treatment.It is further explained that acid treatment is more beneficial to the preparation of MFC by subsequent high-pressure homogenization.According to the response surface results,the optimal technology parameters were that the concentration of HCl is 8%,the reaction time is 80 minutes,the temperature is 75?,the yield of cellulose is 78.75%.The effect of different homogenization times on the structure and properties of MFC was further studied in this paper.The effects of homogeneous number on the microstructure and mechanical properties of MFC were analyzed by using SEM,XRD and universal testing machine.The crystallinity increases with the increase of the homogeneous times.However,when the homogeneous times is more than 15 times,their increase is getting smaller.The variation of tensile strength,modulus of elasticity and transmittance of MFC film is the same trend.With the increase of homogenization times,the average degree of polymerization and average molecular weight of MFC decrease and the rate of change also decreased after 15 times of homogenization.It is illutrate that the homogeneous efficiency began to decrease after 15 times.Therefore,considering the factors of various aspects,the 15 times is suitable for preparing MFC and the average diameter of MFC is 15 nm.The deep eutectic solvents were synthesized by choline chloride with oxalic acid,urea and glycerol respectively.In this paper,the feasibility of using deep eutectic solvents to prepare MFC with SR as raw materials is preliminarily discussed.MFC with an average diameter of 27 nm can be obtained by using the misture of choline chloride and oxalic acid pretreated SR and then homogeneous treatment 15 times.Compared with the MFC films after acid treatment,the tensile strength and modulus of elasticity of ChCl-O film is large,but the elongation at break is smallIn this paper,the MFC-WPC films were prepared by the way of physical blending.The effects of the addition of MFC on the mechanical properties,solubility and water vapor permeability of WPC films were investigated.With the increase of the amount of MFC,the tensile strength of the WPC-MFC film increases at first and then decreases,the elongation at break decreases,and the water vapor permeability decreases and then increases.With the increase of MFC content,the solubility of WPC-MFC membrane decreases and then intends to stable.