韧皮结构对罗布麻生物脱胶的影响

针对目前生物脱胶仍存在的效率低、质量不稳定等问题,以罗布麻为研究对象,从成分组成与结构分布等角度分析了罗布麻韧皮组织对生物作用的的抗性屏障。结果表明：罗布麻韧皮组织胶质组分为45%~55%,是麻纤维中胶质含量最高的;且罗布麻韧皮组织胶质层较厚,纤维束排列整齐有序,直接接触脱胶介质的表层组织中,外为角质层,内层为木质素层,结构致密,疏水性高,可及度低;罗布麻韧皮组织对大肠杆菌和金黄色葡萄球菌的抑菌率分别为22%和14%;罗布麻韧皮组织中的高含量胶质、特殊超微结构以及抑菌物质的存在,构成罗布麻韧皮组织在生物脱胶过程中所需要破除的多层次抗性屏障。     

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.     

Extraction and Characterization of Lignocellulosic Fibers from Girardinia Bullosa (Steudel) Wedd. (Ethiopian Kusha Plant)

ABSTRACT

Currently, eco-friendly products have been given great attention as the world is being polluted severely by non-biodegradable products and by-products. Different textile products have their own share in affecting the environment. This research is focused on exploring alternative bast fiber products to support the supply chain and to assess the possibility of using this fiber as a substitute to already available bast fibers. Kusha fiber was extracted and optimized from Ethiopian kusha plant stem – Girardinia bullosa (Steudel) wedd. – using caustic soda solution by varying the concentration, temperature, and time using design expert 6.0.10, quadratic model software. Tensile property, chemical composition, X-ray diffractometer (XRD), Fourier-transform-infrared spectroscopy (FTIR), fiber morphology, and thermogravimetric analysis (TGA) of the fiber were determined. Fiber characterization showed its tensile strength, and the cellulose content was equivalent to or even better than other bast fibers. Morphology of the fiber was similar to that of typical cotton with visible lumen and a slightly flat surface. Therefore, this new extracted fiber has a great potential to be used for different applications such as fiber-reinforced composites, textile furnishing, apparel, and nanocellulose extraction.     

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.     

A novel ionic liquid degumming process for Apocynum venetum

A novel degumming process for Apocynum venetum was presented using ionic liquid (IL)–water mixture in the paper. Optimum performance for the degumming of Apocynum venetum fiber was obtained in 80% (m/m) 1-butyl-3-methylimidazolium acetate ([BMIM][Ac]) at a temperature of 130 °C for 6 h, and the solution was maintained at the liquor ratio 1:20. The Apocynum venetum fibers before and after degumming were characterized by Scanning electron micrographs, Fourier transform infrared spectroscopy, and X-ray diffraction. The result showed that the Apocynum venetum fibers degummed with IL were longer than traditional chemical method, and the breaking strength of fiber with IL degumming process was significantly improved in comparison with traditional chemical method. Therefore, the IL–water degumming for Apocynum venetum fibers could dissolve the gum of fibers, and improve the spinnability of Apocynum venetum distinctly.     

Survey and Recent Report on Enzymatic Processing of Bast Fibers

SUMMARY

In reference to previous presentations during meetings of Working Group 2 (WG2): “Bioprocessing of Bast Fibres,” acting within the COST Action 847 Project “Textile Quality and Biotechnology,” a further update of current world knowledge on biological processing of fiber plants and textiles was prepared. This survey covers the research on utilization of particular groups of enzymes in these processes. Main areas of enzyme application in bast fiber textile industry, according to literature from 2001-2004 are: degumming of bast fibers and scouring in textile industry (before and after bleaching).

The report also covers the results of studies on enzymatic processing of fiber plants carried out at the INF, in which the work is continued on application of enzymes in: degumming of flax straw, modifying of the short technical flax fibers, linen and hemp fabrics modification, and bonding of lignocellulosic composites.     

Degumming of ramie bast fibers by Ca2+-activated composite enzyme

In recent years, special attention has been paid to the application of biotechnology in the textile industry. In this study, composite enzyme (contained pectatelyase/hemicellulase/laccase) was employed to degum the ramie bast successfully. Interestingly, the activities of enzymes were enhanced by promotion of Ca²⁺ activated remarkably. The test of degummed ramie fiber performance demonstrated that fiber fineness, breaking strength, whiteness, and residual gum of fibers have greatly improved. Further, the structure and morphous of the fibers before and after degumming was examined and analyzed. The results showed that the gum, hemicellulose, and lignin were removed effectively and treated fibers had the typical cellulose I structure suitable for direct textile and other applications. These outcomes suggested that Ca²⁺-activated composite enzyme could degum the gum of ramie bast effectively, which provided a method to improve the quality of ramie fibers and a theoretical basis for flax degumming technique on an environmentally-friendly basis.     

Extraction of Unconventional Bast Fibers from Kydia calycina Plant and their Characterisation

The Kydia calycina fibers were screened out from various plant sources through the water retting method and then the time duration for extraction of fibers was optimized. After optimization, the extracted Kydia calycina fibers were compared with cotton, flax, and jute fibers on the basis of physical and mechanical properties. The morphology of extracted fibers was also studied through SEM. The results showed that the Kydia calycina plant produces better quality bast fibers with respect to plants like jute and flax.     

Screening and identification of Acinetobacter junii for Apocynum vernetum L. fiber enzymatic retting

There are many kinds of ketones with antisepsis functions in the Apocynum vernetum L. fiber (ALF), but its enzymatic retting is difficult. In order to select the appropriate ALF enzymatic retting strain, wastewater from ALF retting was analyzed to screen a strain with high pectinase activity. Of the analyzed strains, the maximum pectinase activity measured was of the #2 strain: 103.2 IU/ml at a zymogenic time of 12 hrs at 37°C. The retting experiments verified that this strain was well suited for ALF; the residual gum rate of ALF was 15.26% and its fiber physicochemical properties were similar to those fibers which were chemically retted. The strain was determined to be a new retting strain, Acinetobacter junii, according to a 16S rDNA sequence analysis in combination with morphology, and biophysical and biochemical tests using fermentation, catalase, methyl red and gelatin liquefaction. As a new pectinase‐producing strain, Acinetobacter junii could be utilized in industrial enzymatic retting productions after further process optimization and can replace the conventional chemical retting process due to its improved fiber quality and reduced environmental pollution.     

麻纤维的改性及其增强复合材料的研究现状

对常见的几种麻纤维与高性能化学纤维的性能进行简单对比,详述了麻纤维表面改性的研究现状。介绍了国内外麻纤维复合材料的应用情况,指出麻纤维增强复合材料具有广泛的应用前景。     

脱胶方法对棉秆皮纤维成分及结构的影响

对原棉秆皮不同部位进行化学成分分析,利用常温水沤、常压脱胶及高压脱胶对棉秆皮进行处理,对脱胶后棉秆皮进行化学成分分析．实验结果表明：高压脱胶后棉秆皮纤维中的半纤维素和木质素含量下降最为明显,纤维素含量提高．对不同方法处理后的棉秆皮纤维的长度、线密度进行测量,用SEM、FT-IR、XRD对处理后的棉秆皮纤维表面形态结构、聚集态结构进行了表征,同时对脱胶后的棉秆皮纤维进行强伸性能等测试并得出断裂曲线．     

罗布麻抑菌物质及其作用机制的研究进展

为阐明罗布麻抑菌功能的物质基础,促进罗布麻纤维在医疗保健用纺织品领域的开发和应用,综述了罗布麻韧皮和精干麻纤维中存在的主要抑菌物质,包括:黄酮类化合物、鞣质、甾体及其苷类、香豆素类化合物、酚酸类和苯甲醛类化合物、脂肪酸以及挥发油。分析了各类抑菌物质的化学成分和抑菌活性,并着重从抑制核酸合成、破坏细胞膜、抑制能量代谢、影响脂肪酸合成、抑制运动性、阻断电子传递链、抑制酶活性、减弱营养物质的吸收以及通过过氧化和自氧化形成具有毒性的降解产物等方面介绍了抑菌作用机制。最后针对精干麻纤维抑菌物质的来源问题,指出韧皮中功能性成分在脱胶过程中的演化行为应成为未来研究的一个重要方向。     

Study on the Application of Kenaf Core as a Composite Reinforcement: Injection Molding of Kenaf Core/Poly(l-lactide) Compounds

Injection molding was performed using poly(l-lactide) (PLLA) as a matrix and by varying the reinforcements, i.e., dry-distilled kenaf core (D-core) or untreated kenaf bast fibers, and the physical properties for these composites were subsequently compared. The dry-distillation was able to reduce the moisture content of D-core by a maximum of 4.2% as compared with untreated control core. As a result, the hydrophobicity was increased, which contributed to favorable Charpy impact strength and tensile properties of the D-core/PLLA composite relative to the kenaf bast fiber/PLLA composite. Moreover, the puffing phenomenon, which arises when heating with a microwave oven due to the vaporization of water dispersed within the interfacial regions and associated softening of the PLLA matrix by the heated vapor, was completely suppressed for the D-core/PLLA composite, whereas a large puffing ratio was observed for the kenaf bast fiber/PLLA composite. Reducing the moisture content also effectively suppressed the occurrence of transesterification reactions, leading to a decrease in the molecular weight of PLLA. However, the apparent nucleation effect of the D-core remains slightly inferior to that for the hydrophilic bast fibers due to its stronger affinity for PLLA molecules.     

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.     

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.     

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...     

韧皮纤维生物脱胶制浆的研究及发展

简单介绍了果胶的结构、化学组成及生物脱胶机理,详细总结了韧皮纤维酶法和发酵浸渍法脱胶制浆的研究、应用和发展情况,并对影响发酵浸渍法制浆原料和脱胶菌株的特性,特别是脱胶过程中主要外界因子进行了综述.     

Characterization of Untreated and Alkaline-Treated Salago Fibers (Genus Wikstroemia Spp.)

Salago fiber (genus wikstroemia spp.) is a bast natural fiber native of the Philippines. This fiber is found all over this country and has various applications, e.g. as handmade paper, currency paper, or bank notes. In this study, untreated and 5 wt% NaOH-treated Salago fibers was characterized chemically, physically, thermally, and morphologically for the first time. It was found that the treatment increases density and improves the mechanical properties of the fiber. Fourier transform infrared spectroscopy analysis revealed stretching O–H and C–H alkane groups at 3330 cm^?1 and 2918 cm^?1 respectively and confirmed lignin reduction for the treated fiber. Thermogravimetric analysis showed that treated fibers possessed greater thermal stability. Scanning electron micrographs used to measure fiber diameters showed the rugged surfaces of untreated fibers and the glossier but more distorted surfaces of the treated ones.     

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。