納米纖維素改性聚偏氟乙烯膜材料性能研究
發(fā)布時間：2018-09-11 12:47
【摘要】：本論文以纖維素漿粕為原料,制備了納米纖維素(CNF)、硅烷偶聯(lián)劑KH-540改性納米纖維素(K-CNF),并將CNF、K-CNF對聚偏氟乙烯(PVDF)進行共混改性,采用浸沒-沉淀相轉化法制備出CNF/PVDF膜材料和K-CNF/PVDF.膜材料,以提高PVDF膜的滲透性能、親水性能、抗污染性能和力學性能。對CNF、K-CNF以及共混膜材料的各方面性能進行了表征。使用CNF/PVDF膜材料和K-CNF/PVDF膜材料分別超濾處理牛奶蛋白料液,探究了兩種膜材料處理牛奶蛋白料液的最優(yōu)工藝條件,考察了膜清洗方法的清洗效果。分別從熱力學和動力學角度對CNF/PVDF膜材料和K-CNF/PVDF膜材料的成膜機理做出探討,使用旋轉流變儀系統(tǒng)研究了CNF/PVDF和K-CNF/PVDF鑄膜液的流變學性質。CNF呈棒狀纖維結構,直徑為20nm-50nm,長度為200-550 nm,結晶度較纖維素漿粕有所提高。將CNF與PVDF共混制備CNF/PVDF膜材料,得出CNF/PVDF膜材料的最優(yōu)制備條件,即：PVDF濃度為16 wt%,CNF濃度為0.5 wt%,溶劑為N,N-二甲基乙酰胺(DMAc),致孔劑PVP K30質量分數(shù)為3 wt%,凝膠浴為去離子水。對比純PVDF膜,最優(yōu)制備條件下制備的CNF/PVDF共混膜的滲透性能提高了72.0%,抗張強度和斷裂伸長率分別提高了18.2%和36.4%,接觸角從81.4。降低至66.9。膜材料的衰減系數(shù)從44.59%降到31.65%。使用硅烷偶聯(lián)劑KH-540改性CNF制備出K-CNF。AFM表征表明K-CNF維持了CNF的形貌,長度為200-500 nm,直徑為30-40 nm,FTIR與XPS表征共同證明KH-540與CNF發(fā)生了偶聯(lián)反應。XPS結果顯示K-CNF表面羥基的數(shù)量少于CNF。當K-CNF質量分數(shù)為0.5 wt%時,K-CNF/PVDF共混膜各方面性能達到最佳,與純PVDF膜相比,K-CNF/PVDF共混膜的滲透、親水及抗污染性能均有顯著提升,抗張強度提高了36.77%,斷裂伸長率提高了61.18%。相比于CNF/PVDF膜,K-CNF/PVDF膜的力學性能得到進一步改善。熱力學研究表明CNF和K-CNF的引入分別使PVDF/DMAc/H2O體系的濁點線向PVDF-DMAc軸靠近,體系變得熱力學不穩(wěn)定,減弱了溶液體系對水的容納能力,促進了相分離。動力學研究表明CNF和K-CNF的引入分別提高了PVDF鑄膜液的凝膠速率,加快了凝膠成膜的進程。CNF/PVDF鑄膜液與K-CNF/PVDF鑄膜液的非牛頓指數(shù)均小于1,故均為假塑性流體。分別升高CNF、K-CNF和PVDF的濃度,PVDF鑄膜液的非牛頓指數(shù)降低,恒剪切粘度、零剪切粘度、粘流活化能和模量均升高。CNF/PVDF膜材料和K-CNF/PVDF膜材料處理牛奶蛋白料液的最佳操作條件均為：0.1MPa的操作壓力,1g/L的牛奶蛋白料液濃度,料液的pH值：11,料液溫度：40℃�？疾炝四で逑捶椒▽NF/PVD F膜材料和K-CNF/PVDF膜材料的清洗效果。對于兩種膜材料,氫氧化鈉溶液清洗+水力反沖洗法的清洗效果最好。
[Abstract]:In this paper, nano-cellulose (CNF), silane coupling agent KH-540 modified nano-cellulose (K-CNF) was prepared by using cellulose pulp as raw material, and CNF,K-CNF was blended to modify polyvinylidene fluoride (PVDF). CNF/PVDF membrane material and K-CNF / PVDF were prepared by immersion-precipitation phase inversion method. Membrane materials to improve the permeability, hydrophilicity, pollution resistance and mechanical properties of PVDF membranes. The properties of CNF,K-CNF and blend film were characterized. CNF/PVDF membrane material and K-CNF/PVDF membrane material were used to ultrafiltration the milk protein material respectively. The optimum processing conditions of two kinds of membrane materials to treat milk protein material were investigated and the cleaning effect of the membrane cleaning method was investigated. The film forming mechanism of CNF/PVDF and K-CNF/PVDF membrane materials was studied from the viewpoint of thermodynamics and kinetics, and the rheological properties of CNF/PVDF and K-CNF/PVDF casting solution were studied by rotating rheometer. The crystallinity of 20nm-50nm in diameter and 200-550 nm, in length was higher than that of cellulose pulp. CNF/PVDF membrane materials were prepared by blending CNF with PVDF. The optimum preparation conditions of CNF/PVDF membrane materials were obtained, that is, the concentration of CNF/PVDF was 16 wt%,CNF, 0.5 wt%, solvent was NN- dimethyl acetamide (DMAc), pore-inducing agent PVP K30, and the mass fraction of PVP K30 was 3 wt%, gel bath as deionized water. Compared with pure PVDF membrane, the permeability, tensile strength and elongation at break of CNF/PVDF blend membrane were increased by 72.0%, 18.2% and 36.4%, respectively, and the contact angle was increased from 81.4% to 81.4%. Down to 66.9. The attenuation coefficient of the membrane material decreased from 44.59% to 31.65%. The K-CNF.AFM characterization of CNF modified by silane coupling agent KH-540 showed that K-CNF maintained the morphology of CNF. The length of 200-500 nm, was 30-40 nm,FTIR and XPS. The results of KH-540 coupling reaction with CNF showed that the number of hydroxyl groups on K-CNF surface was less than that of CNF.. When the mass fraction of K-CNF is 0.5 wt%, the properties of K-CNF / PVDF blend membrane are the best. Compared with pure PVDF membrane, the permeation, hydrophilicity and pollution resistance of K-CNF / PVDF blend membrane are improved significantly, the tensile strength is increased by 36.77 and the elongation at break is increased by 61.18. Compared with CNF/PVDF membrane, the mechanical properties of K-CNF / PVDF membrane were further improved. Thermodynamic studies show that the introduction of CNF and K-CNF makes the cloud point line of PVDF/DMAc/H2O system close to the PVDF-DMAc axis, and the system becomes thermodynamically unstable, which weakens the water holding capacity of the solution system and promotes the phase separation. Kinetic studies show that the introduction of CNF and K-CNF increases the gelation rate of PVDF casting solution, and accelerates the gelation process. The non-Newtonian exponents of both CNF / PVDF and K-CNF/PVDF casting solutions are less than 1, so they are pseudoplastic fluids. By increasing the concentration of CNF,K-CNF and PVDF respectively, the non-Newtonian index of PVDF casting solution is decreased, and the constant shear viscosity and zero shear viscosity are obtained. Viscosity flow activation energy and modulus were increased. The optimal operating conditions for milk protein solution treated with CNF / PVDF membrane material and K-CNF/PVDF membrane material were: 1 g / L operating pressure of 1 g / L, 1 g / L of milk protein concentration, pH value of feed solution: 11, feed temperature: 40 鈩，
本文編號：2236730
[Abstract]:In this paper, nano-cellulose (CNF), silane coupling agent KH-540 modified nano-cellulose (K-CNF) was prepared by using cellulose pulp as raw material, and CNF,K-CNF was blended to modify polyvinylidene fluoride (PVDF). CNF/PVDF membrane material and K-CNF / PVDF were prepared by immersion-precipitation phase inversion method. Membrane materials to improve the permeability, hydrophilicity, pollution resistance and mechanical properties of PVDF membranes. The properties of CNF,K-CNF and blend film were characterized. CNF/PVDF membrane material and K-CNF/PVDF membrane material were used to ultrafiltration the milk protein material respectively. The optimum processing conditions of two kinds of membrane materials to treat milk protein material were investigated and the cleaning effect of the membrane cleaning method was investigated. The film forming mechanism of CNF/PVDF and K-CNF/PVDF membrane materials was studied from the viewpoint of thermodynamics and kinetics, and the rheological properties of CNF/PVDF and K-CNF/PVDF casting solution were studied by rotating rheometer. The crystallinity of 20nm-50nm in diameter and 200-550 nm, in length was higher than that of cellulose pulp. CNF/PVDF membrane materials were prepared by blending CNF with PVDF. The optimum preparation conditions of CNF/PVDF membrane materials were obtained, that is, the concentration of CNF/PVDF was 16 wt%,CNF, 0.5 wt%, solvent was NN- dimethyl acetamide (DMAc), pore-inducing agent PVP K30, and the mass fraction of PVP K30 was 3 wt%, gel bath as deionized water. Compared with pure PVDF membrane, the permeability, tensile strength and elongation at break of CNF/PVDF blend membrane were increased by 72.0%, 18.2% and 36.4%, respectively, and the contact angle was increased from 81.4% to 81.4%. Down to 66.9. The attenuation coefficient of the membrane material decreased from 44.59% to 31.65%. The K-CNF.AFM characterization of CNF modified by silane coupling agent KH-540 showed that K-CNF maintained the morphology of CNF. The length of 200-500 nm, was 30-40 nm,FTIR and XPS. The results of KH-540 coupling reaction with CNF showed that the number of hydroxyl groups on K-CNF surface was less than that of CNF.. When the mass fraction of K-CNF is 0.5 wt%, the properties of K-CNF / PVDF blend membrane are the best. Compared with pure PVDF membrane, the permeation, hydrophilicity and pollution resistance of K-CNF / PVDF blend membrane are improved significantly, the tensile strength is increased by 36.77 and the elongation at break is increased by 61.18. Compared with CNF/PVDF membrane, the mechanical properties of K-CNF / PVDF membrane were further improved. Thermodynamic studies show that the introduction of CNF and K-CNF makes the cloud point line of PVDF/DMAc/H2O system close to the PVDF-DMAc axis, and the system becomes thermodynamically unstable, which weakens the water holding capacity of the solution system and promotes the phase separation. Kinetic studies show that the introduction of CNF and K-CNF increases the gelation rate of PVDF casting solution, and accelerates the gelation process. The non-Newtonian exponents of both CNF / PVDF and K-CNF/PVDF casting solutions are less than 1, so they are pseudoplastic fluids. By increasing the concentration of CNF,K-CNF and PVDF respectively, the non-Newtonian index of PVDF casting solution is decreased, and the constant shear viscosity and zero shear viscosity are obtained. Viscosity flow activation energy and modulus were increased. The optimal operating conditions for milk protein solution treated with CNF / PVDF membrane material and K-CNF/PVDF membrane material were: 1 g / L operating pressure of 1 g / L, 1 g / L of milk protein concentration, pH value of feed solution: 11, feed temperature: 40 鈩，
本文編號：2236730
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