| In this paper,the acetylation modified nanocellulocellulose(A-CNF)with different degrees of substitution was prepared by hydrophobic modification of bleached sulfate conifed wood pulp(SWBK).The effects of acetic anhydride dosage,reaction temperature and reaction time on the degree of acetylation modification were discussed.A compound emulsion with good stability was prepared by substituting A-CNF for traditional surfactant.The effects of A-CNF dosage,substitution degree and initiator dosage on the properties of the compound emulsion were discussed.The pore structure and strength properties of the filter paper were significantly improved when emulsion was applied to impregnate the base paper of diesel filter paper.Firstly,using bleached sulfate coniferous wood pulp(SWBK)as raw material and acetic anhydride as acetylation reagent,the acetylation modified nanocellulose with different substitution degree was prepared by changing the dosage of acetic anhydride,reaction temperature and reaction time.The experimental results showed that the substitution degree of A-CNF increased with the increase of the amount of acetic anhydride,the extension of reaction time and the increase of reaction temperature.When the size was10 g,acetic anhydride dosage was 3.16 g,6.3 g,9.45 g,12.6 g,15.75 g,18.9 g,reaction time was 2 h,reaction temperature was 70℃,A-CNF substitution degree was 0.5,0.59,1.55,1.89,2.1,2.13,respectively.When the slurry was 10 g,the reaction temperature was30℃,40℃,50℃,60℃,70℃,80℃,the reaction time was 2 h,and the acetic anhydride dosage was 6.3 g,the substitutions of A-CNF were 0.11,0.15,0.39,0.48,0.59,0.58,respectively.When the size was 10 g,reaction time was 0.5 h,1.0 h,1.5 h,2.0 h,2.5 h,3.0h,reaction temperature was 70℃,acetic anhydride dosage was 6.3 g,A-CNF substitution degree was 0.18,0.43,0.51,0.59,0.58,0.6,respectively.Overall consideration,the acetylation effect of cellulose was the best under the conditions of 10 g slurry,12.6 g acetic anhydride,2 h reaction time and 70℃ reaction temperature.Secondly,A-CNF was applied to the polymerization of composite emulsion.By measuring the particle size,Zeta potential,solid content,conversion rate,gel rate,calcium stability and centrifugal stability of the emulsion,the influence of A-CNF dosage,substitution degree and initiator dosage on the performance of the emulsion was analyzed.The experimental results showed that with the increase of the amount of A-CNF,the degree of substitution and the amount of initiator,the properties of the emulsion showed A rising trend.When the amount of A-CNF is 1.1%,the performance of the emulsion reaches the best,and then increasing the amount of A-CNF will have adverse effects on the stability of the emulsion.The results of calcium ion stability and centrifugal stability of the emulsion showed that when the initiator dosage reached 0.45 g,the emulsion stability reached the best,and then with the increase of initiator dosage,the emulsion stability showed a decreasing trend.Considering the emulsion stability and preparation cost,the optimal emulsion performance was achieved when the amount of A-CNF was 1.1%,the degree of substitution was 1.89 and the amount of initiator was 0.45 g.Finally,the influence of compound emulsion on the properties of diesel filter paper base paper was studied.The experimental results showed that the pore structure and strength properties of filter paper were improved with the increase of A-CNF content in the emulsion,the increase of A-CNF substitution degree in the emulsion and the increase of emulsion content in the impregnation solution.The maximum aperture of filter paper decreased from 39.42 μm to 32.67 μm,the average aperture decreased from 13.42 μm to9.94 μm,and the rupture resistance increased from 232.47 k Pa to 356.35 k Pa when the additive amount of A-CNF in the emulsion reached 1.1%.Its transverse tensile strength and longitudinal tensile strength were increased from 3.2 k N/m to 4.39 k N/m and 1.39 k N/m to1.95 k N/m,respectively.The tightness was also improved,while the permeability of filter paper was reduced.When the substitution degree of A-CNF in the emulsion increases and the emulsion content in the impregnation solution increases,the performance of diesel filter paper base paper will also be affected.Considering the influence of emulsion on the pore diameter,strength performance,permeability and tightness of diesel filter paper,when the amount of A-CNF in the emulsion is 1.1%,the degree of substitution is 1.89,and the amount of emulsion in the impregnation solution is 3%,it has the best improvement effect on the comprehensive performance of filter paper. |
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