红麻纤维及其造纸基本特征（下）

红麻纤维及其造纸基本特征（下）邝仕均王菊华薛崇昀王锐林茹（中国制浆造纸工业研究所，北京，１０００２０）４红麻纤维的超微结构为进一步研究纤维形态对成纸物理性能的影响，笔者对红麻纤维的超微结构进行了研究。４１红麻木质部纤维超微结构图４红麻木质部纤维横切...     

The Influences of Fibre Parameters on the Tensile and Flexural Response of Lightweight Thermoplastic Kenaf Fibre Reinforced Metal Composites

ABSTRACT

The increasing demand for high performance and lightweight materials has stimulated the development of alternative materials, namely fiber metal laminates (FMLs). FML is a sandwich structure which is formed by bonding the metallic layers with composite as core constituent using an adhesive agent. In this study, the mechanical behavior of FMLs with the core constituents of environmental friendly kenaf bast fiber reinforced polypropylene composites bonded with aluminum skin layers was investigated. The effects of fiber compositions (50, 60, and 70 wt.%), fiber lengths (30, 60, 90 mm), and alkali treatment on the mechanical responses of FML were investigated. The overall results revealed that the increase of fiber composition and fiber length reduces the mechanical strength of FML owing to the agglomeration of natural fibers when the fiber length exceeds the critical limit. However, the chemical treated kenaf bast fiber reinforced FML showed a significant enhancement of the mechanical properties in comparison to the non-treated fiber reinforced FML owing to the improved fiber-matrix adhesion level.     

Experimental particleboards from Kenaf plantations grown in Greece

Hibiscus cannabinus L.) plantation grown in N.Greece during the period June–October 1996 provided the raw material for experimental particleboards. After harvesting, the kenaf stems were storaged under shelter for a week, the core of each stem was separated from bark and both were dried at about 20% and 10% moisture content, respectively, and chipped by a hammermill. Kenaf core, bast fibers and industrial wood chips were mixed in various proportions in order to produce three-layer E2 grade UF bonded particleboards. Kenaf core chips were characterized by a lower slenderness ratio than wood chips of the middle layer. Bulk density of both core chips and fibers was lower than that of wood chips. Substitution of wood chips with kenaf core chips in the middle layer up to 75% slightly affects static bending and internal bond of the boards, but reduces screw holding strength and increases water absorption and thickness swelling; a 100% substitution deteriorates all properties except static bending. In boards with surface layers from kenaf bast fibers or from fibers:wood chips (50:50), static bending and surface roughness are improved, while the other properties tested are deteriorated. Substitution of kenaf core chips in the middle layer with fibers in proportion 50% negatively affects the board properties except static bending. It can be concluded that core chips and bast fibers from kenaf stems may substitute industrial wood chips in the middle and surface layers of the boards, respectively, up to 50%.

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Versuchsspanplatten aus griechischen Kenaf Plantagen

Hibiscus cannabinus L.) in N. Griechenland. Nach der Ernte wurden die Kenafstengel für eine Woche unter Dach gelagert, dann wurde das Holzgewebe im Stengelinneren von der Rindenschicht getrennt, anschliessend auf ca. 20% bzw. 10% Feuchtigkeit getrocknet und beides in einer Hammermühle zerkleinert. Die Herstellung dreischichtiger harnstoffharzverleimter (E₂ Typ) Spanplatten erfolgte unter Verwendung verschiedener Beimischungen aus Kenafholzsp?nen, Kenaffasern und Industrieholzsp?nen. Kenafholzsp?ne und Kenaffasern zeichnen sich durch eine niedrigere Streudichte als Industrieholzsp?ne aus; darüberhinaus weisen Kenafholzsp?ne einen niedrigeren Schlankheitsgrad auf im Vergleich zu den Mittelschichtsp?nen der Industrie. Der Ersatz von Industrieholzsp?nen durch Kenafholzsp?ne in der Plattenmittelschicht bis zu einem Anteil von 75% beeinflusst unwesentlich die Biege-, und Querzugfestigkeit der Platten, hat aber eine negative Auswirkung auf das Schraubenhalteverm?gen, die Dickenquellung und die Wasseraufnahme; ein Zusatz von 100% Kenafholzsp?nen zur Mittelschicht bewirkt eine Verschlechterung aller Spanplatteneigenschaften mit Ausnahme der Biegefestigkeit. Spanplatten, deren Deckschichten aus reinen Kenaffasern oder aus einer Beimischung von Kenaffasern und Industrieholzsp?nen in einem Verh?ltnis von 50:50 bestehen, weisen h?here Qualit?t bezüglich Biegefestigkeit und Oberfl?chenrauhigkeit auf, aber niedrigere hinsichtlich der übrigen Eigenschaften. Der Ersatz von Kenafholzsp?nen durch Kenaffasern in der Plattenmittelschicht hat, abgesehen von der Biegefestigkeit, einen negativen Einfluss auf alle Platteneigenschaften. In ihrer Gesamtheit führte die Untersuchung zu dem Resultat, dass der Zusatz von Kenafholzsp?nen und Kenaffasern in der Mittelschicht bzw. der Deckschicht von Spanplatten bis zu einem Anteil von 50% m?glich ist.

     

Removal of Heavy Metal Ions from Aqueous Solutions Using Lignocellulosic Fibers

Abstract

Spruce, coconut coir, sugarcane bagasse, kenaf bast, kenaf core, and cotton were tested for their ability to remove copper, nickel and zinc ions from aqueous solutions as a function of their lignin content. The fibers were analyzed for sugar and lignin content and extracted with di-ethyl ether, ethyl alcohol, hot water, or 1% sodium hydroxide.

The order of lignin content in un-extracted fibers is coconut coir > spruce > kenaf core > bagasse > kenaf bast > cotton. The fiber with the highest level of heavy metal removal was kenaf bast that had a very low level of lignin, showing that removal of heavy metals does not correlate with lignin content. Cotton, with about 1% lignin, was very low in metal ion sorption while all of the fibers containing lignin did remove heavy metal ions showing that lignin does play a role in metal ion sorption. Extraction with the various solvents removed different cell wall components and did change heavy metal sorption that indicates that cell wall chemistry and architecture may also be important factors in the sorption of heavy metals from aqueous solutions using lignocellulosic fibers.     

Diversity and Characteristics of Kenaf Bast Degumming Microbial Resources

Kenaf is one of the most important natural fiber crops. Traditional degumming with water retting causes serious environmental pollution and reduces the quality of fiber products. The development of kenaf industry is hindered by high production cost. Microbial degumming is suitable for kenaf bast degumming because of its high efficiency, energy conservation, low pollution, and high quality, among others. Through enrichment and screening from water sample, soil sample, and humus sample, we concentrated and identified 92 bacterial strains that could degrade kenaf bast colloid. The strains belonged to 11 genera and 16 species. Five of these strains did not produce cellulase and the weight loss rate of the kenaf bast fiber raw material was more than 20%. These strains belonged to Bacillus subtilis, Paenibacillus polymyxa, Clostridium acetobutylicum, Bacillus alcalophilus, and Erwinia chrysanthemi and were assigned with serial numbers from K1–K5, respectively. This study is the first to report the function of Bacillus pumilus, B. alcalophilus, Clostridium tertium, Brevibacillus brevis, Pectobacterium carotovora, E. chrysanthemi, and Tyromyces subcaesius in kenaf bast degumming. Pectinase and mannanase were the key enzymes in the degumming of kenaf bast.     

Extraction and Characterization of Calotropis gigantea Bast Fibers as Novel Reinforcement for Composites Materials

The aim of this study is to scrutinize the use of Calotropis gigantea bast fibers as potential reinforcement in polymer composites. The bast fibers were extracted from the Calotropis gigantea plant bark and some of them were treated with alkali (5 wt.%) solution. The chemical composition, physico-chemical structural properties of the untreated and the alkali treated Calotropis bast fibers were studied. The results of chemical composition analysis indicated that alkali treatment removed most of the non-cellulose materials as confirmed by the FTIR analysis. The X-ray diffraction results exhibited that the crystallinity index of the alkali treated fibers increased in comparison with the untreated fibers, which agrees with the results obtained in the mechanical tests. The tensile strength and modulus of the alkali treated fibers were found to be higher whereas the elongation at break was lower than the untreated fibers. Thermal stability of alkali treated fibers was lower than that of the untreated fiber. Scanning electron micrographs showed roughening of the surface of the fiber due to the removal of the surface impurities and non-cellulosic components on alkali treatment.It can be concluded that alkali treatment is an effective method to improve the surface and mechanical properties of Calotropis bast fibers to be used in composite materials.     

红麻皮,龙须草纸浆黑液的特性

本文对红麻皮、龙须草原料的化学组成和不同制浆条件蒸煮纸浆黑液的物化性能进行了分析，红麻皮纸浆黑液含硅量低，粘度低，纸浆黑液能满足碱回收要求，而龙须草纸浆黑液含硅量与粘度均较高，需进行适当处理。     

胡麻双螺杆法皮杆分离后的制浆性能研究

本文主要研究双螺杆法分离胡麻韧皮部和木质部纤维所得纤维的制浆性能,以及加入NaOH等药品对其制浆性能的促进作用。结果发现,双螺杆法可使胡麻韧皮部和木质部纤维得以很好的分离(总得率可达40.4%),加入药品后韧皮部纤维100g/m2定量纸张的抗张和撕裂指数以及耐折度可达56.36 N.m/g、42.84 mN.m2/g和168次,比不加药品是高出了25%、30%和60%左右。与此同时,木质部纤维在经过磨浆处理后也可成浆,其50g/m2定量纸张的抗张和撕裂指数以及耐折度可达42.47N.m/g、5.30 mN.m2/g和10次,与不加药品相比提高了约100%、70%和200%。因此,综合可知,双螺杆法可将胡麻韧皮部和木质部纤维得以较好的分离,加入一定量NaOH等化学药品可提高其制浆性能,最终可针对两种纤维的性质,将二者进行合理利用,提高胡麻作为制浆造纸原料的利用效率。     

Evaluation and Impact Factors of the Mechanical Properties of Phloem Bundle Fibers Obtained from Kenaf Germplasm

The mechanical properties of kenaf phloem bundle fibers are valuable for reinforced composites or boards, more so than similar materials also used in textile or papermaking applications. 55 kenaf germplasm studied here showed an average phloem bundle fiber tensile strength of 643.6 MPa and an average elastic modulus of 23.3 GPa after chemical retting treatment. 19 of these kenaf germplasm had fiber tensile strengths >700 MPa, which can be attributed to intensive breeding programs. The fiber tensile strength and elastic modulus of kenaf germplasm had a significant positive correlation, but there was no such correlation between a fiber’s mechanical properties and its diameter or agronomic characteristics. Among 56 hybridized combination F₁ generations, the highest tensile strength was 928.3 MPa from a combination of No.30 of Xinan Wuchi × Guatemala 4. Therefore, breeding and screening are both useful for improving the mechanical properties of kenaf phloem bundle fibers. However, the effects of the used bundle fiber preparation method or cultivation year on the fiber’s mechanical properties were more pronounced than those of the type of kenaf germplasm or breeding operation used. The mechanical properties of kenaf phloem bundle fibers treated by chemical retting were superior to those treated using natural retting.     

Mechanical Characterization and Water Ageing Behavior Studies of Grewia Serrulata Bast Fiber Reinforced Thermoset Composites

Natural fiber-reinforced polyester composites were prepared using bast fibers as the reinforcement which were extracted from Grewia serrulata trees. Chemical treatments such as alkali pretreatment followed by permanganate treatment, acetylation and silane treatment were exclusively applied to modify the fiber surface. Hand lay-up technique with compression molding was adapted for the fabrication of axially oriented fiber reinforced composites. Tensile, flexural and impact strength properties of the specimens prepared were evaluated following the standard procedures. The SEM images of the fractured surfaces shows improvement in compatibility between the chemically treated fibers and the matrix. It was found that the tensile and flexural strengths of chemically treated fiber-reinforced polyester composites have significantly improved when compared to untreated fiber-reinforced polyester specimens. The properties of 1200 hrs water aged specimens were found deteriorated considerably due to diffusion of water into the composite material system. The chemical treatment of fibers prior to fabrication of composites improves the resistance to water absorption tendencies.     

阻燃剂处理红麻杆的阻燃热解动力学研究

文章以高纯度脒基脲磷酸盐为阻燃剂对红麻杆进行阻燃处理,分析了红麻杆的阻燃性能和热解行为,并计算红麻杆的活化能。结果表明:对比纯红麻杆,载药率达到15%时红麻杆达到难燃标准,热解炭化阶段起始温度降低,终止分解温度延后,热降解反应活化能降低。     

从木素物理性质比较AP及AS预处理对红麻秆芯部的作用

以红麻秆芯及经过碱性过氧化氢预处理（ＡＰ）和碱性亚硫酸钠预处理（ＡＳ）后的红麻秆芯为研究对象,分离出磨木木素,并从相对分子质量及其分布、玻璃化转移温度等方面研究了３种磨木木素的物理性质的差异。同时研究了３种料片的弹性模量同温度的关系。研究认为,在本实验条件下,ＡＳ预处理对红麻秆芯的性质有显著的作用,是制备化学机械浆较好的预处理方法;而ＡＰ预处理,对红麻秆芯的作用程度较弱。     

Influence of various retting methods on properties of kenaf fiber

Gum, as the important noncellulosic tissue present in kenaf fiber, has a close relation with downstream processing and product properties, so the predominant task in pretreatment of kenaf fiber for textile application, retting, is to remove gum including pectin, hemicellulose, lignin, and other impurities without damage to cellulose fiber. The traditional retting method is water retting; that is, the harvested kenaf bast is soaked in natural water (rivers or tanks) in which indigenous bacteria attack the gum in an anaerobic process, yielding much water pollution. Currently, much interest has been focused on various retting methods in order to seek one environmentally-friendly method. Therefore, microbe, chemical, water, and microbe–chemical rettings are performed in this experiment. Retted kenaf fibers at optimal conditions of various retting methods are then characterized and compared by light microscopy and indices consisting of residual gum content, fineness, tenacity, elongation, and softness. In addition, chemical oxygen demand (COD) is also tested. The results indicate that microbe retting induces higher residual gum content and lower elongation but better tenacity and softness and finer fiber; chemical retting gives lower tenacity and thicker fiber; water retting produces weak, poor quality fiber; and microbe–chemical retting produces moderate indices.     

非木材纤维的APMP制浆第一部分:红麻和谷草类纤维原料

目前的研究成果表明,将红麻和谷草类原料用碱性H2O预处理后进行盘磨机械法成浆,其浆料强度性能可与杨木APMP相媲美。相对来说,红麻APMP浆料易于漂白,目前主要应用于抄造印刷书写纸、薄页纸和高白度纸板,应用范围基本同于杨木APMP和商品浆BCTMP。与红麻APMP相比,谷草类APMP浆料的漂白相对较困难一些。正因如此,后者仅限于生产低白度浆料,用于抄造新闻纸和低白度纸板。     

The Dimensional Distribution of Kenaf and Apocynum Fibers

ABSTRACT

In this research, single fiber cell separation method was studied and optimized. More than 200 fiber cell dimensional sizes of kenaf and apocynum were analyzed. Furthermore, the diameter changes of kenaf fiber cell before and after different degumming treatments were also explored. Results showed that the average length and diameter of kenaf fiber are 2.16 mm and 10.56 μm, while the average length and diameter of apocynum fiber are 9.04 mm and 7.41 μm. It was also found that the average diameter of kenaf and apocynum fibers decreased with the degumming process, and the diameter distribution became more even.     

红麻粉/聚丙烯复合材料性能研究

以聚丙烯(PP)为基体,选用两种红麻粉[包括红麻韧皮粉(KB)、红麻芯秆粉(KS)]分别作为填料,采用双螺杆挤出共混造粒及模压成型方法制备红麻粉/聚丙烯复合材料,测试了复合材料的力学性能并观察其微观结构,分析了KB与KS的含量对复合材料的力学性能的影响,以及采用硅烷偶联剂进行改性处理对红麻粉与聚丙烯基体之间的相容性的影响。结果表明:随着红麻粉含量的增加,复合材料的拉伸性能逐渐下降,弯曲强度则逐渐增加;当红麻粉质量分数达到20%时,KB/PP和KS/PP两种复合材料的弯曲强度都出现最大值,分别为41.33、39.29 MPa;红麻粉质量分数由5%增加到25%,复合材料的拉伸模量和弯曲模量不断增加,冲击强度则出现下降;采用硅烷偶联剂进行改性处理可以有效地改善红麻粉与聚丙烯基体之间的相容性。     

红麻木质部化机浆残余木素的特性

本文对红麻本质部化机浆磺化和Ｈ２Ｏ２漂白后的残余酶解木素的特性进行了研究，研究结果表明：磺化和漂白后木素的提取率下降，残余木素的平均分子量减小，磺化后红麻木质部酸溶木素含量增加，木素中酯键和烷基芳基醚键等连接型式有一定程度的断裂，木素自由基减少，共轭羰基、邻醌结构和酚羟基有所增加，Ｈ２Ｏ２漂白可以破坏部分邻醌结构和共轭羰基，而木素中甲氧基、酚羟基含量有所上升。     

棉秆皮纤维的草酸软化处理工艺

改进棉秆皮纤维在纺织中的应用,利用草酸对棉秆皮纤维进行软化处理。采用正交实验,并结合直观分析与方差分析方法,得到实验因素对棉秆皮纤维可挠度的影响程度以及棉秆皮纤维软化处理的最佳工艺参数;在最佳工艺参数下,棉秆皮纤维可挠度为2.55 T/(m?tex)、断裂强度为3.13cN/dtex;在显著水平α=0.01,焙烘温度对处理后棉秆皮纤维可挠度有显著影响。通过D/MAX-2400型X射线衍射分析仪对棉秆皮纤维测试与相关分析计算,得到软化处理后棉秆皮纤维的结晶度为64.9%,小于未处理棉秆皮纤维的结晶度。     

Interdependence of moisture,mechanical properties,and hydrophobic treatment of jute fibre-reinforced composite materials

Despite cheap and sustainable in nature, the use of natural fiber composites is limited due to their high moisture absorption, poor fiber–matrix interface, and lack of data on evolution of properties when subjected to environmental factor such as temperature and humidity. The aim of this research is to study the interdependence of moisture regain, hydrophobic treatment, and the mechanical properties of jute fiber-reinforced composite materials. Composite samples made from treated and untreated jute fiber-reinforced composites were exposed to humid environment and their moisture regain, mechanical properties and fiber-matrix interface was tested at given time intervals until four weeks. The composites produced with hydrophobic treated reinforcement showed lesser moisture regain and improvement in the tensile and flexural strengths compared to untreated fabric composite. A clear improvement in fiber-resin interface was observed by scanning electronic microscopy. The dynamic mechanical analysis of treated and untreated composites was conducted in a temperature range 20–140 °C. An increase in the storage modulus of treated composite materials was noted as compared to untreated ones. Furthermore, it was concluded that developed composite loss their mechanical properties linearly with immersion time. However, this aging was slow in treated fabric composites especially hybrid fluorocarbon and fluorocarbon.     

全秆红麻KP制浆用碱量的优化

通过对纤维筛分及蒸煮、漂白各项性能指标的综合分析,探讨了全秆红麻KP制浆用碱量的最优化问题。结果表明,对所研究的原料样品,用碱量18%时中长纤维含量最高、未漂浆及漂白浆的各项强度指标也最优。