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马尾松TMP纤维LMS改性及其表面化学和形貌表征的研究-彭新文-2009

2013年06月17日 11:52 彭新文 点击:[]

 

 作者姓名  彭新文
 中文论文题名  马尾松TMP纤维LMS改性及其表面化学和形貌表征的研究
 外文论文题名  STUDY ON THE LMS MODIFICATION OF MASSON PINE TMP AND CHARACTERIZATION OF SURFACE CHEMISTRY AND MORPHOLOGY
 论文提交日期  2009-06-18
 学位年度  2009
 中文论文关键词  马尾松TMP,LMS,生物改性,表面化学,表面形貌
 外文论文关键词  Masson Pine TMP, LMS, bio-modification, surface chemistry, surface morphology

 

中文论文文摘


    机械浆和化学机械浆因为具有得率高、挺度和松厚度好、光学性能优异等特点,近年来在造纸工业用纤维中所占的比例逐年上升。然而,由于机械浆和化学机械浆纤维表面的木素含量较高,其表面被胞间层和软化的木素覆盖着,这种表面性能决定了其纤维间结合力小,强度无法与化学浆相比,因而生产高级纸张时无法完全取代化学浆,这在一定程度上阻碍了机械法和化学机械法制浆工艺的发展。
    本课题利用一种对环境友好、能耗低、对纤维损伤小的生物酶技术对TMP纤维表面进行改性处理,去除覆盖在纤维表面的部分木素和抽提物成分,从而改善纤维的强度性能。通过对比研究优化出了最佳漆酶/介体体系(LMS)改性工艺。并利用SEM、AFM、XPS等现代仪器分析技术对漆酶/介体体系(LMS)改性机理作了较为系统深入的研究。
    研究了漆酶NS51003/介体体系(LMS)改性对未漂马尾松TMP性能的影响,优化了酶改性温度、pH值、酶用量、介体用量、酶改性时间对纸浆强度性能、白度及松厚度的影响。结果表明,LMS处理后纸浆可漂性提高,白度提高3.80%ISO;纸页抗张强度、撕裂强度、耐破强度均得到明显的改善,但同时松厚度也有一定程度的下降。漆酶与ABTS组成的LMS对未漂马尾松TMP改性的适宜条件为:漆酶用量5LAMU/g,温度50℃,介体用量0.05%,pH值5.0,处理时间90min,通氧气。
    研究了漆酶NS51003/介体体系(LMS)改性对未漂马尾松TMP H2O2漂白性能的影响,探讨了不同H2O2用量及漂白时间对纸浆光学性能、强度及松厚度的影响。结果表明,LMS处理后的纸浆比原浆的可漂性提高,白度增值最高可达4.04%ISO;纸页不透明度,吸收系数及松厚度均有一定幅度的下降;光散射系数几乎不受影响;纸页物理强度上升,返黄值有所降低。
    LMS改性能够使未漂马尾松TMP纤维的胞间层甚至初生壁产生剥蚀,在磨浆过程中更易暴露出更多富含碳水化合物的层结构,纤维更容易吸水润涨,纤维结构更加疏松,纤维更加柔软,更容易分丝帚化,同时在打浆过程中纤维的切断作用也减少。LMS改性能较大幅度的提高浆料的成纸强度,其抗张指数、撕裂指数分别提高37.30%和47.33%,但松厚度下降20.33%。
    AFM的图像表明 TMP原浆纤维的表面被一层致密的,且外形和尺寸不一的颗粒状木素和抽出物覆盖着,纤维的表面并没有看到明显的特定取向的细小纤维束,纤维表面起伏较大,比较粗糙;经过LMS处理后,纤维表面颗粒状木素变小变少,在纤维的表面能够明显看到细纤维的取向,取向角大约为45°,纤维表面相对平整,粗糙度变小。
    利用XPS对LMS改性前后TMP纤维表面氧碳比(O/C)的分析结果表明,LMS改性后TMP纤维表面的氧碳比(O/C)上升了6.35%;对TMP纤维表面C1s峰的研究表明,经LMS改性后的纤维表面C1峰下降了12.5%。说明LMS改性后TMP纤维表面木素和抽提物减少,暴露出了更多的亲水性基团,碳水化合物的含量提高。

 

外文论文文摘


    High yield pulps, such as mechanical and chemi thermo mechanical pulp has been increasingly used in paper industry for many paper products by virtue of their high bulk and stiffness, superior optical properties and good printability. However, comparing which chemical pulp, mechanical and chemimechanical pulps have lower capacity of inter fiber bonding because their fiber surface are usually encased by rigid middle lamella and melted lignin which leads to high lignin content on the fiber surface. Such a strength property of mechanical and chemimechanical pulps is limited to replace kraft pulp for making fine paper, and these disadvantages have become drawbacks for the mechanical pulping process.
    In this study, a new fiber modification technique: LMS, which is environmentally friendly, consumes less energy and causes damage to the fiber, was used to treat TMP fibers by using remove a minor fraction of lignin and extractives on the fiber surface The purpose of LMS treatment is to improve paper strength properties. Scanning electron microscope, Atomic Force Microscopy, X-ray Photoelectron Spectroscopy were used to investigate the mechanism of fiber LMS modification.
    The masson pine unbleached TMP was treated with laccase together with a mediator and thereafter bleached with hydrogen peroxide (H2O2). The effects of such factors as enzyme treatment temperature, pH value, enzyme dosage, and mediator dosage and enzyme treatment time on the pulp whiteness, bulk and strength were analyzed in this paper. At the optimum conditions, the TMP brightness increased 3.11%ISO compared to the sample pulp; the tensile index and the tear index also increase visibly, the bulk decreased. The modification conditions were optimumed: 5LAMU/g laccase dosage, temperature 50℃, ABTS 0.05%dosage, pH 5.0, modification time 90min.
    The masson pine unbleached TMP was treated with laccase together with a mediator and thereafter bleached with hydrogen peroxide (H2O2). The influence of such factors as the dosage of H2O2 and the bleaching time on the pulp whiteness, bulk and strength were analyzed in this paper. At the optimum conditions, the TMP brightness increased 4.04%ISO compared to the sample pulp; the opacity, the light absorption coefficient and bulk decreased; the light scattering retained stabilization. The tensile index, the tear index and the PC increased visibly.
     The change of fiber characteristics during the refining in the TMP with laccase treatment process by scanning electron microscope (SEM) was investigated in this paper. The results showed that the energy consumption of secondary refining of TMP treated by the laccase treatment was lower than the untreated pulp,the middle lamella even the primary wall were corroded ,The auto-adhesion between fibers occurred,the the tensile index increased 37.30% visibly, the tear index increased 47.33%, the bulk decreased 20.33% and the CA decreased.
    The AFM analysis showed that the fiber wall of TMP fiber surface was covered with lignin and extractive which had different shapes and dimension, the surface was coarse. After LMS modification, the lignin and extractive decreased markedly, and their shape and dimension were also decreased. So the surface of fiber became less roughness.
    The results of XPS analysis showed that the LMS modified TMP fibers had a higher O/C ratios and lower C1 percentage than that of the control pulp fibers, and the C1s peak shifted to high binding energy direction. This implies that LMS modified fiber had less lignin and extractives, and more hydrophilic groups and carbohydrate of the fiber surface, which helpful to form hydrogen bond.
    

 

 

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