【作者】 郭延柱；

【导师】 秦梦华；

【作者基本信息】 山东轻工业学院 ， 制浆造纸工程， 2010， 硕士

【摘要】 纤维和细小纤维悬浮于水中时,由于半纤维素、氧化纤维素和氧化木素上某些功能基的离子化,导致纤维带有负电荷。这些功能基包括羧基、磺酸基、酚羟基、醇羟基等。纤维电荷是制浆造纸过程中的一个重要参数。它不仅可以影响各种阳离子助剂如助留助滤剂、施胶剂、增强剂等的留着,而且对于纤维的吸水润胀、柔顺性、纤维间的结合及磨浆性能等至关重要。纤维电荷可来源于制浆造纸所使用的植物纤维原料本身,也可来源于制浆造纸各工段,如氧脱木素、H₂O₂漂白等。论文系统研究了碱性H₂O₂处理对杨木P-RC APMP和CTMP纤维电荷特性的影响,对未处理浆及碱性H₂O₂处理浆的纤维表面形态和性能进行了分析,并研究了碱性H₂O₂处理过程中磨木木素的结构变化。碱性H₂O₂处理可以明显增加杨木P-RC APMP纤维的羧基和表面电荷含量,且随着NaOH和H₂O₂用量的增加、处理温度的提高以及处理时间的延长,浆料中的羧基含量、表面电荷以及可溶解电荷均呈增加的趋势。纤维电荷的增加有利于纤维吸水润胀能力的提高以及磨浆性能的改善。ESCA分析结果表明,P-RC APMP经碱性H₂O₂处理后,氧碳比提高,表面抽出物含量明显降低,同时表面木素含量也有所降低。利用凝胶渗透色谱（GPC）、³¹P-NMR和二维核磁共振波谱对碱性H₂O₂处理后杨木P-RC APMP的木素结构进行了分析。³¹P-NMR分析表明,碱性H₂O₂处理后,杨木P-RC APMP残余木素中的脂肪羟基和羧基含量增加,而总酚羟基及各酚羟基含量降低,说明木素受到了一定程度的氧化。GPC结果表明,碱性H₂O₂处理后,浆料残余木素的数均分子量、重均分子量及多分散性均略微增加。残余木素的二维核磁共振波谱分析表明,碱性H₂O₂处理后,木素的愈创木基结构被氧化而紫丁香基结构保持稳定。木素侧链α碳上的羰基和双键发生了氧化,导致α-羧基增加,这可能是木素中羧基含量增加的原因。木素中的β-β和β-5结构保持稳定,而具有Cα-OR和Cα=O的β-O-4结构易被氧化降解。杨木CTMP碱性H₂O₂漂白过程中,NaOH用量、H₂O₂用量、漂白温度及漂白时间均对纤维的羧基含量、表面电荷含量及浆中的溶解电荷有较大影响。而H₂O₂用量、处理温度及处理时间对浆料Zeta电位的影响不如NaOH强烈。碱性H₂O₂漂白可以提高成纸的物理强度,降低纸张的光散射系数。与未漂浆相比,碱性H₂O₂漂白浆纤维的长度、宽度变化不明显,而纤维的扭结指数和卷曲指数明显下降,同时纤维的保水值明显增加,说明纤维的吸水润胀能力得到改善。ESCA分析发现,碱性H₂O₂漂白导致杨木CTMP纤维表面抽出物和表面木素含量明显降低。³¹P-NMR分析表明,碱性H₂O₂漂白过程中,杨木CTMP的木素结构的变化规律与P-RC APMP相似,即木素中的脂肪羟基和羧基含量增加,总酚羟基含量降低。GPC分析结果表明,碱性H₂O₂漂白后杨木CTMP残余木素的数均分子量、重均分子量及多分散性均有所降低,说明木素受到了一定程度的降解。残余木素的二维核磁共振波谱分析表明,碱性H₂O₂处理后杨木CTMP中木素的愈创木基结构被氧化而紫丁香基结构保持稳定;木素侧链α碳上的羰基和双键发生氧化反应,导致α-羧基增加;木素的β-β和β-5结构保持稳定,而具有Cα-OR和Cα=O的β-O-4结构易被氧化降解。更多还原

【Abstract】 Wood fibres and fines in an aqueous system are negatively charged due to ionization of functional groups associated with hemicellulose, oxidized cellulose and oxidized lignin.These functional groups consist of carboxylic acid groups, sulfonic acid groups, phenolic hydroxyl groups, alcoholic hydroxyl groups and so on. Fibre charge is an important parameter during pulp and papermaking process. It not only determines the consumption of cationic additives used in papermaking, such as retention aids, sizes, wet and dry strength resin etc., but also is very important for the swelling ability of wet fibres, fibre flexibility, fibre-fibre bonding, and refinability. The number of fibre charge depends on the origin of fibre, and on the chemical treatments such as pulping and bleaching applied to the fibres, including oxygen delignification, ozone bleaching, and peroxide bleaching.In this paper, the effect of alkaline peroxide treatment on the charge characteristics of aspen P-RC APMP and CTMP was firstly discussed. The conductometric and polyelectrolyte titration were used to determine the carboxyl content and surface charge content, dissolved charge of fibres respectively. Secondly, the technology of surface analysis, such as ESCA, was used to study fibre surface properties of treated and control pulps. Finally, the structural changes of residual lignin after alkaline peroxide treatment were analyzed.The results indicated that alkaline peroxide treatment could increase carboxyl content and surface charge of aspen P-RC APMP fibres. Moreover, fibre charge was increased with increasing sodium hydroxide, peroxide, elevating the reaction temperature and extending the reaction time. The increased charge groups in the pulp were beneficial to the fibre swelling ability and pulp refinability. ESCA analysis showed that O/C was higher than that of the control pulp, but surface lignin and surface extractive content decreased after alkaline peroxide treatment.Milled wood lignin was extracted from control and alkaline treated pulps of aspen P-RC APMP, and the structure of MWL was characterized by GPC, ³¹P-NMR and 2D-NMR techniques. The functional groups in MWL could be quantitatively analyzed by ³¹P-NMR technique. After alkaline peroxide treatment, the contents of both aliphatic OH and COOH groups in residual lignin were increased while total phenolic OHs were decreased to very low contents. In addition, Mn , Mw and Mw / Mn of MWL extracted from treated pulp were slightly higher than those of control pulp from the results of GPC. 2D-NMR results showed that guaiacyl unit was easier to be oxidized by peroxide than syringyl unit. Carboxylic acids were formed by oxidative attack of peroxide toward the structures ofα-carbonyl and double bond groups in lignin side chain during alkaline peroxide treatment.β-βandβ-5 type sub-structure in lignin were stable to peroxide treatment, whileβ-O-4 type sub-structure withα-carbonyl andα- ether linkage in side chain were degraded.Fibre charge characteristics and paper strength properties of aspen CTMP during alkaline peroxide treatment were also studied in this paper, and the influence of this treatment on the behavior of fibre morphology was further evaluated. The results showed that those parameters, such as sodium hydroxide, peroxide, reaction temperature and time, could affect the carboxyl content, surface charge, and dissolved charge of the pulp. But to the zeta potential, the dosage of sodium hydroxide was more important than the other parameters. The alkaline peroxide treatment improved strength properties but reduced light scattering coefficient of papers. Compared with control pulp, the length and width of treated pulp fibres changed little, but the curl and kink index declined sharply. Furthermore, water retention value was increased, which indicated that the swelling ability of treated fibres was improved. ESCA observation revealed that surface lignin content decreased sharply, while surface extractive content decreased from 7.16% to 5.04% after alkaline peroxide treatment.The structural analysis of MWL obtained from both aspen CTMP control pulp and alkaline peroxide treated pulp was also used GPC, ³¹P-NMR and 2D-NMR techniques. According to the results of ³¹P-NMR, the disciplinarian of CTMP lignin structural changes during alkaline peroxide treatment was similar to P-RC APMP. GPC analysis showed that Mn , Mw and Mw / Mn of MWL obtained from treated pulp were lower than those of the control pulp, indicating that lignin was partly oxidized and degraded. 2D-NMR results showed that guaiacyl unit was easier to be oxidized by peroxide than syringyl unit. Carboxylic acids were formed by oxidative attack of peroxide toward the structures ofα-carbonyl and double bond groups in lignin side chain during alkaline peroxide treatment.β-βandβ-5 type sub-structure in lignin were stable to peroxide bleaching, whileβ-O-4 type sub-structure withα-carbonyl andα- ether linkage in side chain were degraded.更多还原