BRIGHTNESS STABILIZING EFFECT OF UV-ABSORBERS AND RADICAL TRAPPER ON POPLAR APMP PULPS

高得率纸浆残余木质素中对紫外光和近紫外光高度敏感的特定化学结构,结合大气中的氧分子,通过形成游离基中间体而产生发色物质,导致高得率纸浆的光返色(返黄)。紫外吸收类化合物、游离基捕获剂或抗氧剂等处理纸张制止纸张返色的研究已有报道。本文研究了杨木APMP纸浆手抄片添加紫外吸收类化合物(Tinuvin 1130及其前驱物)、游离基捕获剂(氮氧游离基化合物)和抗氧剂(PEG 300)等的工艺条件和方法,对比研究了不同溶剂介质下(有机型和水溶液),添加剂对杨木APMP原浆和还原处理白度稳定性效果。结果表明,Tinuvin 1130与脂肪醇混合物处理还原后,纸浆抗光诱导返色效果尤为显著,该技术方法十分接近工业应用条件,具有潜在的工业应用价值。     

木质素化学改性抑制杨木碱性过氧化氢机械浆返色的研究

中试系统制备了杨木碱性过氧化氢机械浆。分别在水相 /有机溶剂相 /气相等条件下 ,使用乙酐处理杨木化机浆 (原浆及硼氢化钠还原后纸浆 ) ,分别抄造成 60g/m2 纸片 ,测定了不同时间紫外线照射后试样白度。运用返色值 (PCno .)和白度稳定效果 (BSE)等指标评价处理后浆料的光学稳定性。研究结果表明 ,有机溶剂相和气相乙酰化后的纸浆 ,光学稳定性的提高程度取决于乙酐用量和反应时间即乙酰化程度。通过乙酰化 ,可以获取光学完全稳定的杨木化机浆。紫外漫射反射光谱表明 ,杨木APMP机械浆光诱导返色的主要原因是纸浆木质素中羰基和酚羟基团吸收紫外光后变化形成发色结构所致。还原配合纸浆乙酰化处理 ,可能成为防止高得率纸浆返色的工业应用方法     

学原处理改善杨木过氧化氢机械浆白度稳定性研究

分别采用硼氢化钠、亚硫酸氢钠及其混合物处理杨木APMP漂白机械浆，优化了处理条件，研究了不同化学药品对纸浆不处理后改善白度稳定性效果。结果表明：硼氢化钠处理杨木漂白化机浆不但能够显著改善其白度的稳定性而且对纸浆具有漂白作用。加入亚硫酸钠混合处理纸浆可大幅度减少 氢化钠用量，并能取得类似的改善纸浆白度稳定性效果。杨木碱性过氧化氢机械浆光诱导返色有其固有特点，傅立叶红外光谱显示，纸浆木质素中的羰基和酚羟基结构基团是引起纸浆光诱导返色的主要原因。     

化学还原处理改善杨木过氧化氢机械浆白度稳定性研究

分别采用硼氢化钠、亚硫酸氢钠及其混合物处理杨木APMP漂白机械浆，优化了处理条件，研究了不同化学药品对纸浆还原处理后改善白度稳定性效果。结果表明硼氢化钠处理杨木漂白化机浆不但能够显著改善其白度稳定性而且对纸浆具有漂白作用。加入亚硫酸氢钠混合处理纸浆可大幅度减少硼氢化钠用量，并能取得类似的改善纸浆白度稳定性效果。杨木碱性氧化氢漂白机械浆光诱导返色有其固有特点，傅立叶红外光谱显示，纸浆木质素中的羰基和酚羟基结构基团是引起纸浆光诱导返色的主要原因。     

木聚糖酶处理改善速生杨化学机械浆性能的研究

用木聚糖酶处理速生杨化学机械浆(APMP),通过分析检测处理后纸浆的打浆度和成纸物理性能,探讨了木聚糖酶处理对速生杨高得率浆抄造性能的影响.实验结果表明,与未经过木聚糖酶处理APMP浆相比,酶处理后纸浆的打浆度降低10°SR以上,返黄(PC)值下降0.28,抗张指数和耐破指数稍有降低,而撕裂指数提高0.34mN*m2/g,不透明度提高1.1%,松厚度提高0.08cm3/g,戊聚糖含量降低1.64%,酸溶木质素含量稍有降低,纤维素含量和Klason木质素含量相对提高.木聚糖酶处理速生杨高得率纸浆,主要降解纸浆中的木聚糖,对纤维素大分子影响较小.     

杨木高得率制浆技术的最新进展

本文介绍了杨木的纤维特性、化学成份和利用杨木生产高得率纸浆的适应性,以及杨木为原料的漂白化学热磨机械浆（ＢＣＴＭＰ）和碱性过氧化氢化学机械浆（ＡＰＭＰ）。ＡＰＭＰ是９０年代研制成功的高得率制浆新方法,其特点是纸浆得率高、白度高和强度好。该法适用于针阔叶木,特别是杨木。杨木ＡＰＭＰ可代替部分长纤维针叶木浆,配抄低定量胶印新闻纸和涂布纸等。     

小黑杨幼龄材与成熟材制浆性能的比较

以小黑杨幼龄材和成熟材为研究对象,分析比较其化学组成、纤维形态和制浆性能. 结果表明:幼龄材的苯醇抽出物、纤维素、木质素含量高于成熟材,综纤维素含量低于成熟材;幼龄材的纤维平均长度低于成熟材.分别采用硫酸盐法制浆正交试验,分析得出:保温时间、用碱量对幼龄材的纸浆得率和卡伯值的影响非常显著;用碱量和保温时间对成熟材的纸浆卡伯值影响非常显著;在相同蒸煮条件下,幼龄材比成熟材纸浆得率高,卡伯值和聚合度低.     

用紫外分光法测定鱼藤中异黄酮类的总含量

根据鱼藤中异黄酮类化合物在紫外光２１０～２４５ｎｍ及２９０～３０５ｎｍ处具有吸收峰这一特性，提出了用紫外分光法测定鱼藤中异黄酮类总含量的方法．在３００ｎｍ波长处，浓度低于６×２．６１８×１０－３／ｍｏｌ·Ｌ－１时，测定了标准系列的吸光值，结果表明吸光值与浓度近乎直线相关，相关系数为０．９９７７；标准系列吸光值准确性高；加样回收率达９９％以上；测定样品时，重现性好．     

日本落叶松纸浆材造纸性能及工艺成熟期的研究

通过日本落叶松８、１５、２０、２５年生４种年龄木材物理性能和形态，化学分析及纸浆造纸性能的研究，并与美国，加拿大进口的纸浆比较，认为该树种木材纤维素含量高，纤维长、粗浆得率高达４７．３％，而且制浆容易，成本低，纸浆造纸性能较好，是良好的造纸用材树种。分析确定，日本落叶松纸浆材工艺成熟期为１５￣２０年生。     

漆酚硼衍生物的研究(Ⅳ)──硼酸漆酚酯的聚合反应

硼酸漆酚酯具有较漆酚更易聚合的特性。根据元素分析、热分析、红外光谱、紫外光谱、核磁共振氢谱和电子自旋共振谱等的测试结果认为：硼酸漆酚酯的聚合反应发生于其不饱和侧碳链基上；该不饱和碳链基在干燥空气中进行游离基聚合；其分子中的硼原子对该游离基聚合反应具有催化作用。     

Mechanism of size retention on handsheets prepared in rosin soap size-alum systems

The mechanism of rosin size retention in rosin soap size-alum systems was studied on the basis of sizing behavior and the rosin size and aluminum contents of handsheets prepared under normal and particular conditions. Rosin size, aluminum, and calcium contents of handsheets prepared with various stirring times of pulp suspensions after pH adjustment suggested that rosin size components adsorbed on pulp fibers predominantly have the structure of free rosin acid rather than rosin aluminum or calcium salt. When a carboxyl group-blocked pulp was used, the rosin size content clearly decreased. This result shows that pulp carboxyl groups play a significant role in rosin size retention. Electrostatic interactions between dissociated carboxyl groups of pulps and anionic rosin size components through cationic aluminum compounds must be present in pulp suspensions. On the other hand, nonionic interactions in pulp suspensions, which occur particularly around pH 6.2–6.5, may also contribute to rosin size retention and appearance of sizing features. When the carboxyl group blocked pulp was used, some rosin size components were retained in the handsheets in largely coagulated form, resulting in no or quite low sizing levels, when the handsheets were dried at 20°C.This research was presented in part at the 64th pulp and paper research conference of Japan TAPPI, Tokyo, June 1997     

Light source dependence of the photodegradation of wood

The aim of this study was to determine whether artificial ultraviolet (UV) light sources are able to imitate properly the photodegradation of wood caused by sunlight. In this study, wood specimens were irradiated with a xenon lamp and a mercury lamp. The xenon light simulated sunlight only in the case of long-term irradiation. The photoinduced yellowing of wood was faster and greater in the case of short-term exposure to xenon light than that caused by sunlight. The number of UV light-generated carbonyl groups absorbing infrared light around 1700 cm⁻¹ showed good correlation with photoinduced yellowing. On the other hand, mercury light did not simulate sunlight. However, the mercury lamp, as a strong UV light emitter, can be applied to determine the valid limits of the Kubelka–Munk (K-M) equation. Our results show that the K-M equation cannot be applied to determine the absorption properties of the sample if the values of the K-M units exceed 50.     

Solid-state13C-NMR analysis of size components in handsheets prepared by fatty acid soap size-alum systems

The mechanism of paper sizing in fatty acid soap size-alum systems was studied by structural analyses of the size components in handsheets prepared with¹³C-labeled fatty acid soap size. Patterns of sizing performance and aluminum content of the handsheets were similar to those for the rosin soap size-alum sizing systems, although the patterns of calcium content were different. Solid-state¹³C-nuclear magnetic resonance analysis of the handsheets revealed that fatty acid calcium salt was the predominant size component in the handsheets prepared using tap water. This calcium salt is formed from the fatty acid soap size (fatty acid potassium salt) by ion exchange with calcium ion in pulp suspensions and retained on pulp fibers through aluminum compounds originating from alum added. On the other hand, when deionized water was used, free fatty acid was the major component in the handsheets. Fatty acid aluminum salt was present as a minor component in the handsheets prepared in both tap water and deionized water systems. Therefore, all size components (i.e., fatty acid calcium salt, free fatty acid, fatty acid aluminum salt) seem to contribute to the appearance of sizing features.This research was presented in part at the 64th Pulp and Paper Research Conference of Japan TAPPI, Tokyo, June 1997     

A methylflavan with free radical scavenging properties from Pancratium littorale

The isolation of 7,4'-dihydroxy-8-methylflavan (1) from the dichloromethane extract of Pancratium littorale stem was guided by an assay for free radical scavenging activity towards the 2,2-diphenyl-1-picryl-hydrazyl radical (DPPH). The structure of 1 was established by spectrometric methods including UV, EI mass spectrometry, 1H and 13C-NMR. The free radical scavenging properties of 1 were quantified in solution using spectrophotometry.     

Retention behavior of size and aluminum components in handsheets prepared in rosin soap size-alum systems

Handsheets were prepared with rosin soap size and aluminum sulfate under various conditions, and the retention behavior of the rosin size and aluminum components in the handsheets was studied. Pyrolysis-gas chromatography and X-ray fluorescence analysis were used to determine the size and aluminum contents in the handsheets, respectively. When the addition level of rosin soap size varied from 0% to 4% and that of aluminum sulfate was fixed at 2%, the rosin size content increased with the increase in the size addition level, whereas aluminum and calcium contents were roughly constant. Under these conditions, handsheets prepared from fines-free pulp had aluminum contents less than those for the original beaten pulp, probably because the former pulp had a carboxyl content less than that of the latter pulp. Not only the conventional rosin retention mechanism but also mechanism proposed below must exist in the rosin soap size-alum systems. That is, some aluminum compounds originating from aluminum sulfate are adsorbed on pulp fibers immediately after the aluminum sulfate addition. These adsorbed aluminum compounds form cationic sites on pulp fibers, and free rosin acid components with anionic charges are then adsorbed onto the cationic sites of pulp fibers at the wet-end.This research was presented in part at the 46th annual meeting of the Japan Wood Research Society, Kumamoto, April 1996     

Effects of tension wood on kraft paper from a short-rotation hardwood (Populus “Tristis No. 1”)

The physical properties and morphology of kraft paper handsheets obtained from tension wood of intensively managed, 5-year-old trees of Populus Tristis No. 1 were compared to those produced from isolated normal wood of the same stems. Pulp yields of tension wood (TW) and normal wood (NW) were 60 and 53% respectively. Over a beating range of 0–45 minutes, strength properties of TW paper were in all cases noticeably inferior to those obtained from NW. During paper formation, the TW or gelatinous fibers resisted collapse, even upon extended refining, and produced thick, porous sheets of poorly bonded elements. It was concluded that the differential behavior of NW and TW pulps was in several respects analogous to those displayed by earlywood and latewood pulps, respectively, of softwood species as well as thin-vs. thick-walled hardwood fibers. Consequently, it appears that the inferior strength of TW paper is primarily a function of fiber morphology, and the difference in hemicellulose content between NW and TW (viz., lower pentosan content of TW) often cited in the literature as a potential major factor here probably contributes little if any significant effect on ultimate interfiber bonding and paper quality.The experimental phase of this investigation was carried out by K. W. Robinson in partial fulfillment of the requirements of The Institute of Paper Chemistry for the M.S. degree from Lawrence University, Appleton, Wisconsin.     

电子自旋共振在竹材研究中的应用：竹材自由基研究 二

本文分析和讨论了碱处理对苦竹试样自由基的影响,探讨了经水洗使碱性减弱后试样自由基浓度的变化,并对紫外光照射、温度变化导致的自由基浓度的改变作了测定。结果表明,碱处理对试样自由基浓度有明显降低作用;水洗对减弱碱性对于自由基浓度的影响有一定作用,但不显著;紫外光照射对竹材自由基有微弱作用,但对毛竹、杨木自由基有明显影响;温度对自由基浓度有较大影响,但若试样形态不同,温度与自由基浓度变化关系图也有差异。     

The pulp and paper properties of Sirex noctilio infested and fire-damagedthermomechanically pulped,South African grown Pinus patula

Pinus patula is the softwood species most extensively planted in South Africa. However, large portions of these plantings are under threat from Sirex noctilio infestation and occasional forest fires. In this exploratory investigation, the effects of tree age, Sirex noctilio infestation and fire damage to wood from Pinus patula trees on their pulp and paper properties were evaluated. Pulp was produced using the thermomechanical pulping (TMP) process. The energy consumption required to pulp the different pulpwood materials was determined. Pulps were beaten for five different time periods to investigate the development of the fibre properties in response to increasing energy input. Paper properties such as burst, tear strength and breaking length were determined on handsheets manufactured from unbeaten and beaten pulps. Box and line plots and canonical variate analysis biplots were used to statistically analyse the data. It was found that the burst strength of paper produced from healthy trees was significantly higher than that from sirex-infested or fire damaged (burnt) trees. Similarly, the tear strength of paper from healthy and burnt trees was significantly better than from sirex-infested or young trees. No significant differences in breaking length were evident between the pulpwood materials and an increase in beating time did not lead to any improvements. From this study it can be concluded that wood from dead or dying, sirex-infested and young trees produced paper with consistently lower strength properties compared to wood obtained from healthy 12-year-old trees.