1、Section 5 Physical Properties and Utilization of LigninPhysical properties of ligninUtilization of ligninPhysical properties of ligninnPhysical properties of lignin are variable and complicated for many factors. nPhysical properties of lignin depend not only on the origin (kinds of plant) , but also
2、 on the methods of lignin separation（一）（一）General physical properties1、ColornProtolignin is a white material or nearly achromaticitynThe color of lignin formed when the lignin was separated and prepared. nThe different of color (high or low) is due to the different methods of separation and preparat
3、ionnThe lignin colour can be removed by chemical method and so on. nColor of ligninoResidual lignin in pulp and that in black liquor is deeply brownoResidual lignin in bleached pulp is primrose yellow(淡淡黄色黄色)2、Relative densitynThe value is different because of the different determination and prepara
4、tion methodsoMost of the lignin isolated from lignified plant is amorphous powder and its relative density is between 1.3 and 1.5 oThe relative density of Klason lignin of pine is 1.451 determined by water and it is 1.436 determined by benzene o云杉二氧六环木素用水测定的是云杉二氧六环木素用水测定的是1.330，用二氧六环，用二氧六环测定的是测定的是1.
5、391，用比重计法测定的则是，用比重计法测定的则是1.361 3、Optics propertylThe lignin has not optical activity because of the shortage of symmetrical(对称的对称的) carbon atom4、Combustion valuelRelatively high，for example：lThe combustion value of hydrochloric acid lignin of Spruce without ash is 110.0kJ/glThe combustion value of K
6、alson lignin is 109.6kJ/g 5、SolubilitylProtolignin usually does not dissolve in any solvent6、Viscosity The viscosity of lignin solution is low and it is only one-forth of synthetic polymers（二）（二）Molecular weight of lignin and the form of lignin moleculeoRelative molecular weightn木素是一种高分子化合物，原本木素的分子量
7、可高达几十万n分离木素的分子量要低得多，一般仅有几千到几万n磨木木素也只是原本木素中的低分子量部分oX-射线衍射图表明，木素的结构是无定型的，分离出的木素大都是无定型的粉末。o用电子显微镜研究木素的超分子结构状态表明，木素是：n以球状质点状态或n块状质点状态聚集存在的 制浆过程中木素大分子降解溶出的模型 Average molecular weight of MWLsample重均分子量Mw数均分子量MnMw/MnSprucePineAspenReed705066505140535041203760344033001.711.771.491.62The ratio of Mw/Mn refle
8、cts the distribution nature of lignin and it shows that the molecular weight has certain nonuniformityoBecause of the high molecular weight and the absence of hydrophilic groups; it leads to the low solubility of proto lignin in water or usual solvents, even insolubilization.nThe isolated lignin has
9、 certain solubility, but it is variable according to plant species, separation method and solventoWhether it can dissolve in certain solvent lies on the isolated lignin properties , the solubility parameters of solvents and the binding energy of hydrogen bond. oBrauns lignin and organic solvent lign
10、in can dissolve in dioxane（二氧六环）、pyridine、methanol、ethanol、acetone and diluted alkaline solution, but some water must be added. Otherwise, they are nearly insoluble. 碱木素和硫木素在二氧六环中溶解后像是胶体溶液。碱木素和硫木素在二氧六环中溶解后像是胶体溶液。碱木素可溶于稀碱水、碱性或中性的极性溶剂中。碱木素可溶于稀碱水、碱性或中性的极性溶剂中。木素磺酸盐可溶于水中，其溶液是真正的胶体溶液。木素磺酸盐可溶于水中，其溶液是真正的胶体溶
11、液。BraunsBrauns木素、酚木素和许多有机溶剂木素在二氧六木素、酚木素和许多有机溶剂木素在二氧六环中溶解后是澄清的，很像是真溶液环中溶解后是澄清的，很像是真溶液 oIn view of the poor solubility of proto lignin, some hydrophilic groups are introduced onto the macromolecular structure of lignin in order to dissolved out the lignin and separated the fiber. For example:nSulfonic
12、 acid group can bring forth the dissolved lignosulfonic acid. nAlkali can bring forth new hydrophilic phenolic hydroxyl group and make the lignin releaseThis is one of the basis for chemical pulping, too!（四）（四）Thermal property of ligninoThe thermal property refers to thermal plasticity(可塑性）oThe ther
13、mal plasticity of lignin is important for the processing and pulping of wood, especially for the mechanical pulping. o各种木素加热到一定的温度即开始软化，软化温度也即常说的玻璃转化点：o干态的木素一般在127193，随树种、分离方法和分子量大小等而异 o吸水润胀后的木素，软化点大大降低。n随着分子量增大，其软化点上升，差不多呈直线关系 Utilization of ligninoUtilization of lignin degraded productsoUtilizatio
14、n of lignin macromolecule1 Utilization of lignin degraded productsoThe lignin extracted from black liquor reacts with sodium sulfite and leads to the production of lignosulfonate with coniferyl alcohol structure. Then the coniferyl aldehyde is made from coniferyl alcohol. o二甲基硫醚和二甲基亚砜也可由降解木质素制得。o二甲基
15、亚砜是由二甲基硫醚氧化制得的，是多种塑料特别是丙烯腈的优良溶剂甲硫醇2 Utilization of lignin macromolecule碱木素主要用途之一就是对它加以改性制备木素磺酸盐水泥减水剂；木素属于天然高分子聚合物 它的表面积很大，对化学药品有较强的吸附能力，而且具有良好的粘合性 ，可以用于加工胶合芯板 ；。对工业木素进行改性合成阻垢剂既有利于解决造纸废水污染环境的问题，又可提高资源利用率。由造纸黑液木素可制备一系列功能性肥料：螯合肥料，控释肥，活化磷肥和改土肥等，应用相当广泛。木质素磺酸盐用作染料的稳定剂、除虫杀菌剂的分散剂、粘土或固体燃料水悬浮液稳定剂、循环冷凝水的缓蚀阻垢剂等
16、； The paper is sized with modified lignin and the effect is better than rosin sized. The physical strength of paper is improved and the insoluble lignin can also be used as filler increasing the sizing degree. The paper strength can be improved with the addition of modified lignin. Lignin can absorb
17、 ultraviolet radiation and so it can partly replace carbon soot（炭黑）as the filler used for apple wraps.3 Utilization in pulping and papermaking industry The new retention and drainage system composed of lignin or its derivatives and PEO（聚氧化乙烯）can increase dramatically the retention; meanwhile, the paper properties are also improved.oFor example, the combination of Kraft lignin and PEO which is mainly used for recycled pulp and mechanical pulp can increase the retention of fines and fillers; furthermore, it can also decrease the precipitation of resin on paper machine.
