【作者】 高晓艳；

【导师】 潘志娟；

【作者基本信息】 苏州大学 ， 纺织材料与纺织品设计， 2009， 硕士

【摘要】 本课题分别以尼龙6/甲酸溶液和聚-L-乳酸/丙酮/三氯甲烷溶液作为纺丝液,利用自行设计加工的静电纺丝装置进行静电纺丝,并使静电纺纤维沉积在非织造过滤材料的表面,制备了PA6纳米纤维/基布、PLLA微米纤维/基布和PA6/PLLA/基布复合材料。主要研究了复合材料的孔隙结构、透气性和过滤性能,并且对过滤材料的过滤过程进行了初步的计算机模拟。静电纺丝工艺参数的探索:研究了纺丝液浓度、电压、喷丝头和接收屏之间距离(C-SD)、流量、喷丝头内径对纤维形貌结构的影响。确定了PA6静电纺丝的工艺条件:纺丝液浓度22wt%,电压15kv,C-SD距离15cm,喷丝头内径0.45mm,流量0.06ml/h。PLLA的静电纺丝工艺条件:电压20kV,C-SD距离25cm,喷丝头内径0.85mm,流量3ml/h。静电纺纤维/非织造布复合过滤材料的孔隙结构:用计算机图像处理的方法计算分析了复合材料的孔隙结构,研究结果表明:复合材料中的孔隙数量随着静电纺丝时间的增加呈指数增加,PLLA微米纤维复合材料中的孔隙数量比PA6纳米纤维复合材料和PA6纳米纤维/PLLA微米纤维多层复合材料中的少,PA6纳米纤维/PLLA微米纤维多层复合材料中的孔隙数量最多。复合材料中的平均孔隙面积随着静电纺丝时间的增加而下降,其中PA6纳米纤维复合材料和PLLA微米纤维复合材料的孔隙面积呈指数规律下降,PA6/PLLA多层复合材料的孔隙面积呈反“S”规律下降。随着静电纺丝时间的延长,复合材料中的孔隙形状越来越接近圆。复合材料的孔隙率都随着静电纺丝时间的增加而下降。其中,PLLA微米纤维复合材料的孔隙率下降最快;纳米纤维/微米纤维/基布多层复合材料的孔隙率下降速度比纯纳米纤维/基布复合材料快。静电纺纤维/非织造布复合过滤材料的透气性和过滤性:分别研究了以三种非织造布过滤材料为基布的复合材料的透气性和以WZ-CP-3为基布的复合材料的过滤效率,并考察了复合材料的质量因子Q的变化情况。结果表明:以三种非织造布为基布的纳米单层、微米单层和纳米/微米多层复合材料的透气率随着静电纺丝时间的增加而呈指数规律下降。以WZ-CP-3为基布的纳米单层、微米单层和纳米/微米多层复合材料的过滤效率随着静电纺丝时间的增加而增加,静电纺丝时间相同时,过滤效率依次是PA6/PLLA/WZ-CP-3 > PLLA /WZ-CP-3 > PA6/WZ-CP-3。复合过滤材料的质量因子Q随着静电纺丝时间的增加而下降,在3种复合材料中,当过滤效率相接近时,PA6纳米纤维/PLLA微米纤维多层复合材料的Q值最大,即过滤性能是3种复合材料中最好的。非织造布对气体的过滤过程的模拟:在GAMBIT中建立了非织造纤维网的二维和三维模型,并在Fluent中模拟了过滤过程。结果表明:纯气体射流通过二维纤维网时,压力层状增加,并且随着纤维含量的增加,压力逐渐变大。纯气体从进入到流出纤维网的过程中,流速先快速增加,然后剧烈变化,最后下降,并且随着纤维含量的增加,流速增加。随着纤维含量的增加,在纤维网入口处的颗粒物含量有明显增加,纤维网中颗粒的运动情况减弱。在三维模拟中,可以明显看到,流体遇到纤维后形成绕流,使速度和压力发生变化,以及颗粒被捕集出口处浓度下降。更多还原

【Abstract】 Nylon6 solution in formic acid and PLLA solution in both acetone and trichloromethane was electrospun into nonwoven mat with the homemade electrospinning instrument. A common nonwoven fibrous filter was used as a collecting substrate in the electrospinning, so that the electrospun fiber layer and the substrate composed of a composite mat. The porous structure and properties of the composite mat were researched firstly. Then the simple filtration process was simulated with the CFD.Investigation on the technique of the electrospinning process: Solution concentration (BC), Voltage (V), tip-to-collector distance(C-SD), solution flow rate (FR), and inner diameter of spinneret (ID) of the electrospinning process were investigated. Initial optimized spinning parameters for PA6 were: BC 22wt%, V 15kv, C-SD 15cm, FR 0.06m/h and ID 0.045mm; for PLLA were: V 20, C-SD 25cm, FR 3ml/h and ID 0.85mm.Porous structure of the composite mat: PA6/nonwoven, PLLA/nonwoven and PA6/PLLA/nonwoven composite mats were prepared. Porous structure of the composite mats was obtain and analyzed by the computer, the results showed: with the increasing of the electrospinning time, the number of pores in a composite mat increased on the exponential function. The number of pores is the least in PLLA micro-fiber composite filter and the largest in PA6 nano-fiber composite filter. The average pore area in the composite filters decreased with the increasing of the electrospinning time, average pore area in both PA6 nano-fiber and PLLA micro-fiber composite filters decreased on the exponential function, while decreased on the opposite“S”in PA6/PLLA composite filters. With the increasing of the electrospinning time, HCF and the porosity decreased. The porosity of PLLA micro-fiber composite filter decreased the fastest, and PA6 nano-fiber composite filter decreased the slowest.Air permeability and filtration efficiency of the composite mat: with the increasing of the electrospinning time, the air permeability of the composite mats decreased on the exponential function. The filtration efficiency of PA6/WZ-CP-3, PLLA/WZ-CP-3 and PA6/PLLA/WZ-CP-3 was test, and the quality factor (Q) was calculated. Filtration efficiency increased with the electrospinning time increasing, with the same electrospinning time, the filtration efficiency was PA6/PLLA/WZ-CP-3 > PLLA /WZ-CP-3 > PA6/WZ-CP-3.The Q of the PA6/PLLA/WZ-CP-3 is the largest while the filtration efficiency were nearly equal, which means the filtration performance of the PA6/PLLA/WZ-CP-3 is the best.Filtration process simulation: Two-dimensional (2D) and Three-dimensional (3D) models of the nonwoven mat were built in GAMBIT, and the filtration process was simulated in Fluent. With the increasing of the fibers in the nonwoven mat, the pressure and velocity of the fluid increased. While the pure gas flow through the 2D nonwoven mat, the pressure showed lamellar distribution, the velocity changed greatly. While the gas with particles flow through the 2D nonwoven mat, low pressure center appeared, and the velocity changed greatly before and after reach the nonwoven mat. With the increasing of the fibers in the nonwoven mat, the concentration of the particles at the inlet increased, the moving condition of the particles in the nonwoven mat decreased. In the 3D simulation, the pressure and velocity changed when the fluid reach the fibers, and the concentration of particles decreased at the outlet after particles be trapped.更多还原