毛细管模型表征醋纤滤棒空隙结构

Void structure characterization for cellulose acetate filter rod by a capillary model

为了准确量化地表征和研究醋纤滤棒空隙结构,采用了一种毛细管模型表征方法,即将滤棒内部的空隙简化为一束均匀的毛细空管,通过测量滤棒圆周、质量、长度、成型纸厚度和毛细吸水质量5个参数,计算滤棒内部毛细管的半径和数量,分析了不同滤棒样品的空隙结构。结果表明:①方法的重复性较好,毛细管半径和数量测试的相对标准偏差小于0.5%。②常规滤棒样品(圆周24.2 mm)内部约有1600~2200个半径78~90μm的毛细管,细支滤棒样品(圆周17.0 mm)内部约有180~310个半径140~190μm的毛细管。③滤棒加工压降越大,滤棒内毛细管数量越多,半径越小。④由不同丝束加工的同规格滤棒(相同长度、圆周和压降)中毛细管数量和半径存在显著差异。

In order to quantitatively characterize and study the void structure of cellulose acetate(CA)filter rods,a capillary model was adopted and improved.The void inside a CA filter rod was regarded as a bundle of uniform empty capillary tubes.The radii and number of capillaries in the filter rod model were calculated via measuring five parameters,including rod circumference,mass,length,plug wrapper thickness and the amount of moisture absorbed by the capillary.The void structure of different CA rod samples was analyzed.The results showed that:1)The method featured good repeatability with RSDs of tested capillary radius and numbers less than 0.5%.2)There were about 1600-2200 capillaries with the radii of 78-90μm inside a conventional filter rod(circumference 24.2 mm),and there were about 180-310capillaries with radii of 140-190μm inside a slim filter rod(circumference 17.0 mm).3)The greater the pressure drop of a filter rod during processing,the higher the number of capillaries inside the rod and the smaller the capillary radius would be.4)The numbers and radii of the capillaries inside the filter rods of the same specification(with the same length,circumference and pressure drop)processed with different tows differed significantly.