纤维素酶和半纤维素酶改性对漂白针叶木浆性能的影响

分别采用复合纤维素酶、内切纤维素酶和木聚糖酶3种酶对漂白针叶木纤维进行改性处理,比较不同的酶对漂白针叶木浆性能的影响。结果表明:复合纤维素酶对漂白针叶木浆性能影响较大,随着酶用量的增加,浆料滤水性先增加后下降,纤维保水值(WRV)和Zeta电位绝对值先降低后增加,纤维表面亲水性降低,纤维长度急剧下降,手抄片抗张指数先增加后急剧下降;在酶用量5.0 U/g时,纤维平均长度较对照样降低了48.64%,抗张指数较对照样下降了23.23%;内切纤维素酶和木聚糖酶对漂白针叶木浆的影响都比较小,改性处理后WRV和Zeta电位绝对值逐渐降低,但纤维表面亲水性增加,手抄片抗张指数也有所增加。对于造纸工业而言,内切纤维素酶的改性效果较好,当其用量为5.0 U/g时,纤维表面亲水性增加,有利于对纤维进行打浆处理,同时手抄片抗张指数增加到22.04 N·m/g,较改性处理前增加了20.77%。     

马尾松松根木片制浆造纸性能试验研究通过鉴定

福建林学院承担的福建省科技攻关项目:“松根综合利用”(八)马尾松松根木片制浆造纸性能试验研究,已于1988年5月24～25日在福建省南平市通过省级鉴定. 工艺流程:马尾松松根木片→削片→筛选→硫酸盐蒸煮→洗浆→打浆→筛浆→手抄纸页.在试验范围内硫酸盐蒸煮最佳工艺条件为:用碱量22%(以Na_2O计),硫化度     

稻草氧碱浆疏解特性的研究

对稻草经氧碱蒸煮后进行疏解,研究疏解对稻草氧碱浆滤水性能的影响,并分析纤维质量、浆中灰分及硅含量的变化。结果表明:去除杂细胞后浆料的打浆度能降低近10°SR,疏解对浆料滤水性能的下降作用明显,同时疏解对纤维细胞的变形作用影响了浆料的打浆度,而杂细胞的存在与否对疏解浆料的打浆度影响不明显。与除杂浆料相比,未除杂浆料在疏解过程中细小纤维组分增加3.7个百分点,未除杂浆的扭结指数、卷曲指数、纤维宽度以及所含灰分中的硅含量随疏解而下降。     

胡萝卜饮料

1.原料的选择、清洗:选用肉质嫩脆、味甜、纤维少的新鲜胡萝卜,放进萝筐中用高压自来水冲洗,直到洗净为止。 2.将沥干的胡萝卜投入盛有100℃沸水的不锈钢锅中热烫5分钟,捞出沥干后放进切片打浆枫叶进行切片打浆,打浆时加入85℃～90℃的热水(原     

纤维性质对成纸性能的影响

对纤维的三个基本性质－长度、强度和粗度对纸性的影响进行了综述，着重讨论了对强度性质的影响。     

稻草氧碱浆打浆特性的研究

为研究稻草氧碱浆的打浆特性,采用PFI磨考察了不同打浆度对稻草氧碱浆滤水性能、纤维形态的影响,并分析其纸张强度性能的变化。结果表明:纸浆打浆度与保水值在打浆初期快速上升,在打浆后期上升趋缓,但是打浆度在打浆初期能快速上升至55~60°SR,而保水值快速上升阶段仅到45°SR左右;同时杂细胞的存在对滤水性能不利。打浆度35~75°SR过程中,纤维长度的变化不大,未除杂浆纤维长度下降最多约为7.3%,除杂浆纤维长度下降最多约为4.0%,而打浆对纤维表面的细纤维化作用明显。未除杂浆纸张耐破指数和抗张指数在打浆度65°SR时达到最佳,杂细胞的存在会对纸张的抗张强度提高形成一定的阻碍,除杂浆纸张耐破指数和抗张指数在65°SR以上的高打浆度下仍然保持上升的趋势,因而更倾向于在高打浆度、高结合强度要求的纸种当中获得应用。     

不同年龄构树皮的纤维、化学特性与制浆性能研究

对金沙江干热河谷不同年龄构树皮的化学、纤维特性与制浆性能进行研究.结果表明,构皮纤维长、木素含量低,纤维素含量高,纤维形态好,易于成浆.随着年龄的增大,低龄构皮化学组分稍有增大,但至6-7 a,灰分和木素含量增大,纤维素和硝酸-乙醇纤维素含量明显下降,不利于成浆;1%Na0H抽提物一直呈缓慢上升趋势,第6-7年达到最高;构皮纤维长度、长宽比及长纤维比例都随年龄的增长而增加,3-5 a增至最大,第6年后呈快速下降趋势.2-4年生构皮手抄片有较高的结合强度和耐折度,5-7 a后趋于稳定.因此,优质构皮纤维原料最佳收获期为2-5 a,综合经济效益考虑,纤维原料人工林培育最佳周期为2-3 a.     

酶处理对混合杨木P-RC APMP浆打浆性能的影响

探讨了纤维素酶、木聚糖酶处理对混合杨木温和预处理和盘磨化学处理的碱性过氧化氢机械浆(P-RC APMP)的打浆性能和打浆能耗的影响。结果表明:与未经过酶处理浆相比,纤维素酶和木聚糖酶处理可明显改善纸浆的打浆性能和降低打浆能耗,纸浆打浆度提高1.0～6.5°SR,或在相同打浆度下打浆能耗降低10%～25%。纤维素酶处理浆裂断长提高18%,撕裂指数提高14%,耐破指数提高16%,耐折度提高100%。木聚糖酶处理纸浆白度提高1.7度(ISO),纸浆物理强度略有上升。纤维素酶在改善纸浆打浆性能、降低打浆能耗和提高物理强度方面好于木聚糖酶,木聚糖酶在改善纸浆光学性能方面优于纤维素酶。酶处理可以使纸浆纤维结构变得疏松柔软,从而增强纤维间的交织能力。     

六种阔叶木CTMP制浆性能的初步研究

对拟赤杨等６种阔叶木进行纤维形态和化学组成的测定、ＣＴＭＰ制浆、打浆强度分析及漂白工艺的研究，结果表明拟赤杨等几种阔叶木具有较好的制浆适应性。     

两种商品木浆的纸浆性能研究

选取市场上具有代表性的两种商品针、阔叶木浆进行PFI打浆处理,研究在不同打浆度下浆料纤维质量、动态滤水性能、Zeta电位、微观结构等方面的变化,并对不同比例配抄条件下的成纸性能进行考察,结果表明:针、阔叶浆的打浆度与打浆转数之间的关系均符合线性分布:y=17.7503+0.0015x,R^2=0.9914(针叶浆);y=8.8986+0.00275x,R^2=0.9734(阔叶浆);经PFI打浆后,两种木浆纤维长度、宽度变化较小,细小组分含量变化明显;随着打浆度的升高,两者的滤水性能下降,Zeta电位先上升然后基本保持不变;初始打浆度下,随着针叶浆比例的减少、阔叶浆比例的增加,成纸的抗张强度先下降再增大,厚度逐渐下降至不变,定量逐渐增加,柔软度逐渐下降;随着打浆度的升高,成纸的抗张强度增大,厚度、定量逐渐下降,针叶浆成纸柔软度逐渐下降,阔叶浆成纸柔软度先升高再逐渐降低。     

Effects of site on fibre, kraft pulp and handsheet properties of Eucalyptus globulus

? Eight-year old trees from two Eucalyptus globulus Labill. clones planted across three different sites in Tasmania, Australia, were sampled for wood and kraft pulp/handsheet properties.

? Site had a significant effect on all measured properties. Compared with the poor site (Parkham) the wood from the good site (West Ridgley) had on average 11 % lower wood density. The poor site had also greater microfibril angles, shorter fibres at lower pulp yields.

? The handsheets produced with pulp from the poor site resulted in comparatively higher bulkiness, lower burst, lower tear and tensile indices, lower zero span tensile strength, but higher opacity, higher light scattering and higher surface roughness. Significant height effects were found with all wood properties, and also with tear index, zero span tensile strength and opacity.

? Discriminant analysis showed that for 76 out of 100 handsheets the raw material source, i.e. growth site, could be predicted correctly using a set of handsheet properties with tear index and bulk index being most prominent.

? This is unique evidence that site conditions are strongly reflected in handsheet properties produced from Eucalyptus pulp.

     

Effects of pulp freezing and frozen pulp storage on fibre characteristics

Summary A requirement of long-term research on pulp fibres in that the material for study be stored for prolonged periods without deterioration and without changes in properties. In this paper effects of pulp freezing and thawing and of frozen pulp storage on fibre, wet web, and handsheet properties are discussed. A variety of radiata pine kraft pulps, a radiata pine sodium bisulphite pulp, and silver beech and hard beech (Nothofagus species) kraft pulps are examined.The expanded walls and diameters of beaten fibres were contracted by pulp freezing. This behaviour made fibres less flexible and less able to collapse during papermaking operations. The freezing treatment also caused fibre kinks and other fibre configurations which existed in a pulp before freezing to be fixed into position and made somewhat resistant to straightening when in strained wet webs. It was found that extents of fibre kink can be varied depending on the degree to which fibre configurations are forced into a pulp network before freezing. Increasing periods of frozen storage caused the intensity and distribution of bonds redeveloped by the freezing treatment to be progressively modified. Fibre walls were, however, not contracted further by increasing periods of frozen storage.The technical assistance of Miss D. Brookes is gratefully acknowledged     

Application of micromechanical models to tensile properties of wood–plastic composites

Wood–plastic composites (WPC) were produced with white birch pulp fibers of different aspect ratios (length-to-diameter), high-density polyethylene, and using two common processes: extrusion or injection molding. Three additive levels were also used: no additive, compatibility agent, and process lubricant. Fiber size was measured with an optical fiber quality analyzer. Tensile properties of WPC were measured and modeled as a function of fiber aspect ratio. Models were fitted to experimental values using the minimum sum of squared error method. A shift from the oriented fiber case (injection molding) to the randomly oriented fiber case (extrusion) was achieved using a fiber orientation factor. Fiber/matrix stress transfer increased with increasing fiber aspect ratio. Stress transfer was reduced with the use of process lubricant. Unexpectedly, the compatibility agent had the same effect. Fiber strength and stiffness contributions to the composite were lower than those of intrinsic fiber properties.     

Fiber charge characteristics of pulp suspension containing aluminum sulfate

Fiber charge characteristics of pulp suspensions containing aluminum sulfate were investigated with relation to adsorption behavior of aluminum components on the pulp fibers by streaming potential measurement using a particle charge detector, X-ray photoelectron spectroscopy, and X-ray fluorescence analysis. When aluminum sulfate was added to a pulp suspension prepared using deionized water, a streaming potential of the suspension went from negative to slightly negative according to the adsorption of aluminum components on the pulp fibers. Subsequent addition of a dilute NaOH solution to the suspension drastically cationized the fibers in the pH range of around 5 by predominant and homogeneous adsorption of cationic aluminum complexes on the fiber surfaces. However, the aluminum flocs that formed heterogeneously on the fiber surfaces at higher pH by further alkali addition made nearly no contribution to cationization of the fibers, although the abundant aluminum components were retained in the pulp sheets. Therefore, only aluminum cations adsorbed uniformly on the fiber surfaces perform well to control the charge properties of the pulp fibers at the wet end; and the preferential aluminum adsorption behavior on the fiber surfaces, by utilizing the required amounts of hydroxyl ions, probably accounts for the effective cationization of the fibers under acidic to neutral papermaking conditions.This research was presented in part at the presymposium of the International Symposium on Wood and Pulping Chemistry, Seoul, June 1999; at the International Symposium on Environmentally Friendly and Emerging Technologies for a Sustainable Pulp and Paper Industry, Taipei, April 2000; and at the 2000 annual meeting of the Society of Fiber Science and Technology, Japan, Kyoto, June 2000     

Influence of addition of bulking promoter on AKD-sizing performance

Paper density, tensile index, sizing degree, and other properties of the handsheets were measured in term of addition level of bulking promoters and alkyl ketene dimer (AKD). Bulking promoters had clear bulking effects, and in subsequent addition of the AKD, the sheet density was further decreased slightly. Although the density of the handsheet decreased from 0.64 to 0.61 g/cm³ when 0.2% AKD was added with the 0.8% bulking promoter, tensile strength decreased from 20.3 to 19.8 Nm/g. The addition of AKD led to suppression of the decrease in the tensile index. The bulking promoter may also have potential to give sizing effects to the paper sheet as well as the increase in paper thickness. When 0.05% AKD was added together with 0.8% of bulking promoter, the sizing degree of the handsheet was 25.6 seconds, and it was almost the same, 27.3 seconds, as the addition of 0.1% AKD only. AKD retention in the handsheet was determined by pyrolysis-gas chromatography (Py-GC). The addition of the bulking promoter contributed to AKD retention in the handsheet regardless of the sizing degree. Wetting characteristics of the handsheet were determined by contact angle measurements. Surface free energy, γ _s , of the handsheet as calculated from the contact angle decreased as the level of AKD addition increased.     

Methods for the determination of wood properties,Kraft pulp yield and wood fibre dimensions on small wood samples.

A trial set-up with methods for sampling, treatment and analysis of small wood chips are presented in this paper, to determine important wood and fibre properties, like basic density, dry density, volume swelling of wood, Kraft pulp yield, fibre length, fibre coarseness, fibre width, lumen width and fibre wall thickness. The required time for one sample is about 1.5 man-hour, but this requires relatively larger series and trained personnel. Acceptable measurement accuracy is achieved when the volume of the wood sample is at least 1.5 ml, except that of wood volume swelling. To gain acceptable measurement accuracy for volume swelling, the wood volume should be increased to at least 3 ml, and preferably more than 5–6 ml per sample. The level of pulp yield and wood density do not show a significant effect on the measurement accuracy for fibre cross-section dimensions. Fibre coarseness, on the other hand, has a significant influence on these accuracies. A double measurement of fibre coarseness will improve the accuracy to an acceptable level. The method presented here may, together with information about trees and growth locations, form the basis for greater insight into the mechanisms involved in development of wood and fibre properties in trees, which in turn may provide better control and utilisation of wood for pulp and paper production.Abbreviations CWD cell wall density in dry wood=1500 kg/m³ - Ww dry weight of wood (kg) - Vmax green (wet) volume of wood (m³) - Vmin dry volume of wood (m³) - BD basic wood density (kg/m³) - DD dry wood density (kg/m³) - VS maximum volume swelling of wood (%) - Wp dry weight of pulp (kg) - PY pulp yield (%) - C fibre coarseness, the average weight of a unit length of fibre (g/m) - CL average chip length (mm) - CWT average cell wall thickness (m) - FW average fibre width (m) - l average native fibre length in solid wood - L chip length - lc average fibre length in wood chip (mm) - Lc length-weighted fibre length in wood chip (mm) - lw native average fibre length in wood (mm) - Lw native length-weighted fibre length in wood (mm) - LW average lumen width (m) - llw average native fibre length, length weighted, in wood - X average fibre length in chip - Xlw average fibre length, length weighted, in chip     

Understanding and adding value to Eucalyptus fibre

Eucalyptus wood has become one of the most important hardwood resources for pulp mills worldwide. Furthermore, bleached Eucalyptus pulp is used extensively both in paper-making globally where it is included in such diverse products as tissue, packaging, as well as printing papers and in chemical cellulose products such as viscose, acetate and microcrystalline cellulose. This paper investigates and highlights the physical and chemical attributes of the wood and pulp fibre from Eucalyptus that contribute to its popularity in the pulp and paper-making industries and to suggest how these can be enhanced or conserved in the manufacturing process to add maximum value. The fibre properties of macerated wood samples from a range of Eucalyptus species used commercially in South Africa are compared with those of North American hardwoods such as birch, maple and aspen. In comparison to the American hardwoods, the Eucalyptus species were found to have short and thin fibres (on average, fibre length from 0.6 to 0.8 mm and fibre width between 15 and 17 μm, compared with 0.6–1.4 mm and 17–30 μm, respectively, for the American hardwoods. This particular combination of dimensions for the Eucalyptus fibre produces a low fibre coarseness, which is a highly desirable attribute for products such as coated and uncoated papers. The Eucalyptus fibre is therefore reasonably fragile and this makes it particularly vulnerable to damage during the pulp and bleaching processes. Fibre damage occurs throughout the pulp process but is most severe in the mechanical sections such as digester blowing, high shear mixers, medium- and high-consistency pumps as well as low-consistency refining. These areas are highlighted in this paper and possibilities for fibre conservation are discussed.     

Retention behavior of size and aluminum components on handsheets in rosin-ester size/alum systems

Anionic emulsion sizes consisting of rosin triglyceride esters and partly fortified rosin acids (i.e., rosin-ester sizes), have recently been used as internal sizes for alkaline papermaking. In this study, handsheets were prepared from pulp suspensions with alum and a rosin-ester size under various conditions, and sizing degree and size and aluminum contents of the handsheets were determined. Aluminum compounds originating from alum added to the pulp suspensions behave as retention aids of the rosin-ester size even in alkaline papermaking under limited conditions. Carboxyl groups in pulp are the primary retention sites of aluminum compounds in pulp suspensions. They form cationic sites on pulp fibers, and thus the anionic size emulsion particles are adsorbed on pulp fibers by electrostatic interactions. However, the cationic charges of aluminum compounds on pulp fibers decrease and finally disappear completely with the lapse of time after the alum addition by forming ionic bonds between the cationic sites and OH^– ions. Thus, pH values of the pulp suspensions and timing of the size addition strongly influence the retention values of the rosin-ester size and the resultant sizing features.This research was presented in part at the 1995 autumn meetings of the Society of Fiber Science and Technology Japan in Hamamatsu, October 1995     

Influence of deformability of kraft pulp fiber surface estimated by force curve measurements on atomic force microscope (AFM) contact mode imaging

Attempts were made to obtain high-resolution images of an unbeaten bleached softwood kraft pulp fiber surface in water by applying contact mode atomic force microscopy. However, clear topographic images could not be obtained. In order to investigate the possibility of deformation of a pulp fiber surface during scanning, force curve measurements were applied to pulp fiber surfaces. It was found that a pulp fiber in water had a more deformable surface than an air-dried pulp fiber in air. Moreover, the spring constant of it was estimated to be close to that of a cantilever applied for imaging. Therefore, the images of a pulp fiber surface in water were thought to be significantly affected by deformation, which was considered to be an important cause of the unclear images. Parts of this article was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, Japan, March 2003, the 54th Annual Meeting of the Japan Wood Research Society, Hokkaido, Japan, August 2004, the 12th International Symposium on Wood and Pulping Chemistry, Madison, USA, June 2003, and the 13th International Symposium on Wood, Fiber and Pulping Chemistry, Oakland, New Zealand, May 2005