第五节植物纤维形态对纸张性能影响

,Chapter 1 The Composition and Structure of Wood,36,Tianjin University of Science & Technology,第五节 植物纤维形态对纸张性能的影响,(,一,),常见原料的细胞组成比较,针叶材：管胞、木射线管胞和木射线薄壁细胞；,阔叶材：木纤维、管胞、导管、薄壁细胞及木射线薄壁细胞；,禾本科：纤维细胞、杂细胞,(,表皮细胞、石细胞,),。,多数杂细胞由于腔大、壁薄、长度短，制浆时会吸收大量蒸煮药液；,洗浆时会堵塞,洗浆机洗鼓,的网孔，降低洗涤能力；成纸强度低；,表皮细胞在碱法制浆中会增加废液的硅含量，在酸法制浆中则成片状存在、增加,纸病,。,原料的杂细胞含量越高，其制浆造纸价值就越低。,制浆造纸价值：,棉花及麻类,针叶材原料,阔叶材原料,禾本科原料。,杂细胞对制浆造纸的影响,(,二,),纤维形态及其与纸张性质的关系,纤维形态,包括纤维的,长度、宽度、壁厚、腔径,等基本形态指标外，还包括,长宽比、壁腔比以及纤维的粗度,等。,n,i,L,i,数量平均长度,=,n,i,n,i,L,i,2,质量平均长度,n,i,L,i,n,i,L,i,3,二重质均纤维长,=,n,i,L,i,2,n,i :,某级分中纤维数目；,L,i,：,某级分中纤维平均长。,1,纤维的长度（书,38,页）,2,纤维形态的频率分布,n,分布频率 ,X 100(%),n,将纤维按不同长度（或宽度）的大小分级，计算每一级分纤维根数占纤维总数量的百分比例，可得数量分布频率或质量分布频率。,(,二,),纤维形态及其与纸张性质的关系,纤维长度,1,长宽比,= -,纤维宽度,长宽比大的纤维，成纸时单位面积中纤维之间相互交织的次数多，纤维分布细密，成纸强度高，,特别是,撕裂度、裂断长、耐折度,等强度指标,。（书,39,页表,1-19,）,一般认为长宽比小于,45,的原料，应用价值很低。,2,壁腔比,2 X,细胞单壁厚度,壁腔比,=,细胞腔直径,Cell wall thickness,Width,2 X,细胞单壁厚度,刚性系数,=,X100,纤维直径,细胞腔直径,柔性系数,=,X100,纤维直径,纤维的壁腔比不同，则它们的柔软程度不同。壁腔比小（即纤维的柔软性好）的纤维，成纸时纤维间的接触面积较大，故结合力强，成纸的强度高；反之，壁腔比大的纤维则较僵硬，成纸时纤维间的接触面积较小，结合力小，成纸的强度差。,壁腔比,1,为劣等原料。,图：理想的纤维结构,厚壁纤维,A,与薄壁纤维比较。,制浆造纸工程大全,P19,Paper on Close Examination,3,纤维的粗度,(Coarseness),每,100m,长度的绝干纤维的质量,(mg),，用,decigrex(dg),表示。,W=30,CWT=5,W=40,CWT=5,W=30,CWT=10,W=40,CWT=10,Increasing Coarseness mg/m,Relative amount of material in fibre,纤维粗度大于,30dg,的纸浆，造纸的纸页较粗糙，平滑度低；小于,10dg,者，纸页细腻，平滑度好，但是裂断长、耐破度、撕裂度及耐折度下降。,4.,纤维的卷曲因子（,Form factor,或,Curl Index,）,D,L,Form factor = D/L,Curl Index = L/D - 1,6.,扭结指数（,Kink index,）,Measurement of angles,Reported according to Kibblewhites kink index formula,Principle of mechanical refining. Wood chips are fed into the refining zone where they are disintegrated between two grooved discs of which at least one is revolving,.,纤维的扭结是指由于纤维细胞壁受损而产生的突然而生硬的转折。,扭结指数可用单位长度上扭结平均个数（个,/mm,）或单根纤维上扭结平均个数（个,/,单根纤维）表示。,定义：,1,）造纸原料中长度等于或小于,0.2mm,的纤维,2,）造纸原料中通过纤维筛分仪的,200,目筛（,0.074mm,）的纤维,来源：,1,）,初级细小纤维：,木材中原有的小颗粒，如切断的纤维、导管分子、纹孔、射线细胞和薄壁组织细胞（量少）；,2,）,二次细小纤维：,浆料在生产和后续的抄造过程中通过机械处理产生的纤维壁碎片（量多）。,6.,细小纤维（,fines),影响,1,）纸机的运行过程，比如留着、滤水、白水回收系统、助剂效用、干燥速度等；,2,）纸张的性能，比如纸张结构、物理强度性能、光学性能、印刷性能等。,(,三,),纤维形态测定,1,纤维的长、宽度测定,台式投影仪进行；,Kajaani FS,（,100/200/300,）型纤维质量自动测量仪；,纤维质量分析仪（,FQA,）,Fibermaster,/Fibertester,Kajaani 100,纤维分析仪工作原理图,Kajaani 300,Optics Module,Sample out,Capillary,Sample in,Fibre detector,Detector light source (Laser),Polarizers,Measurement (CCD-camera),Measurement light source LED,Optics body,Sample loop,样品回路,漏斗,毛细管,排出,Detection loop,检测回路,激光,1,st,偏振器,毛细管,2,nd,偏振器,纤维检测器,Measurement loop,测量回路,发光二极管,毛细管,CCD,照相机,Measurement,测量,Fibermaster,Fibertester,Fiber Quality Analysis,OpTest Equipment Inc.,Hawkesbury, ON Canada,Values Measured By The Laboratory FQA,Fiber Length,Fiber Width,Fiber Curl,Fiber Kink,% Fines,Coarseness,HWD/SWD Ratio,Shives,(,四,),纤维粗度和细胞壁厚对纸张性能的影响,Wet Fiber Flexibility,Paavilainen, L., Importance of coarseness and fiber length in papermaking. Tappi International Process and Product Quality Conference, 10/1988. pp. 99 - 109.,Apparent Sheet Density,Paavilainen, L., Importance of coarseness and fiber length in papermaking. Tappi International Process and Product Quality Conference, 10/1988. pp. 99 - 109.,Tensile strength,Paavilainen, L., Importance of crossdimensional fiber properties and coarseness for the characterization of softwood sulphate pulp. Paperi ja Puu vol. 75, 5 (1993), pp. 343 - 351.,Wet Fiber Flexibility,Paavilainen, L., Wet fiber flexibility and collapsibility of softwood pulp fibres. Paperi ja Puu 75(1993)9-10, pp. 689 - 702.,Surma-Slusarska, B., Surewitz, W., The effect of chemical composition and anatomical structure of wood on the yield and properties of kraft pulps.,Cellulose Chemistry Technology, 15, 1981, pp. 77 - 97.,Apparent Sheet Density,Paavilainen, L., Influence of morphological properties of wood fibres on sulphate pulp fiber and paper properties. Proceedings of International Paper Physics Conference held in Kona, Hawaii, 9/1991, p. 383 - 395.,Tensile strength,