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Ramie cellulose fibers are common natural fibers with high strength and outstanding biodegradability. However, there are interconnected gummy components covering raw ramie, which need to be removed to extract separated fibers. Here, an effective and environmentally friendly extraction approach using deep eutectic solvent (DES) was developed. The whole degumming technique can be completed in a one-step boiling process at 160°C for 2.5 h. This new method exhibited the capability to remove most non-cellulosic contents without sacrificing the physical properties or chemical structures of cellulose in comparison with the traditional alkaline method. Besides, the DES can be reutilized many times while still maintaining sufficient degumming efficiency. Some by-products in the degumming solution, such as lignin and polysaccharides, can be successfully separated, beneficially realizing recycling economy and sustainable development. The DES degumming method provides an alternative and practical method for ramie fiber extraction. [ABSTRACT FROM AUTHOR]

Ramie fiber is known as the "king of natural fibers," and the key to its wide application is efficient and green manufacturing. Microbial degumming has gradually become a hot area of research due to its environmental protection and mild operating conditions. However, some gummy materials remain after microbial degumming. Xylan is the main component of residual gums; its acetylated branched chains create the space barrier that makes the removal of hemicellulose difficult during ramie degumming. An acetyl xylan esterase (AXE) was obtained from Bacillus pumilus and characterized to solve this problem. Its optimum temperature and pH were 35°C and 8.0, respectively, and it had good temperature and pH stability. These properties were consistent with the conditions of ramie degumming and they laid a foundation for the application of AXE in ramie degumming. Besides, an engineered strain with a high activity of AXE was constructed successfully on the basis of the wild-type degumming strain Pectobacterium carotovorum HG-49 and used for ramie degumming. The removal rate of hemicellulose and total gums by the engineered strain increased by 4.89% and 2.53%, respectively, compared with that of the wild-type strain. Moreover, the role of this AXE in ramie degumming was further proven by X-ray diffraction and scanning electron microscopy. This study showed that AXE played an important role in the removal of hemicellulose in the degumming process of ramie fibers, thus providing a promising degumming strategy for ramie and other bast fiber plants. [ABSTRACT FROM AUTHOR]

To explore high-quality microbial resources with the capability of ramie degumming, we collected soil samples from rotten ramie and straw heaps. After enrichment culture by ramie raw materials, bacterial strains with the potential ramie-degumming function were screened using a pectin-hydrolysis plate. Dominant bacteria were identified by combining colonial morphological characteristics with the molecular biology method, and their ramie-degumming effects were verified through comprehensive biological degumming indices. Results demonstrated that Bacillus aryabhattai, Bacillus thuringiensis, Lysinibacillus fusiformis, and Acidovorax temperans were successfully obtained. The highest pectinase activity, 98.2 U/mg, was found by A. temperans. B. thuringiensis showed the best ramie-degumming effect. The residual gum content, single-fiber linear density, and bundle-breaking strength of the degummed ramie fiber treated with B. thuringiensis were 8.32%, 6.80 dtex, and 7.84 cN/dtex, respectively. The residual gum content of the ramie fiber treated with B. thuringiensis met the textile requirement (<10%), and the values of all other indicators were also satisfactory. Therefore, B. thuringiensis was an excellent strain for ramie degumming, indicating potential industrial applications. [ABSTRACT FROM AUTHOR]

A novel versatile glycoside hydrolase Cel5M was identified from Pectobacterium carotovorum and used in ramie degumming. The full-length Cel5M (GenBank: MH544226) containing the catalytic domain Cel5MD and its carbohydrate-binding module (CBM3) were expressed in E. coli. Both Cel5M and Cel5MD showed a broad substrate spectrum cleaving konjac glucomannan (KGM), carboxymethylcellulose (CMC) and oat spelt xylan. The optimal temperature of Cel5MD was 55oC with CMC and KGM, whereas the optimum temperature of Cel5M was 65oC with KGM and 60oC with CMC. The improved thermal activity with KGM was probably reflected also in the much lower K m with KGM than with CMC, indicating stronger binding of the full-length enzyme with KGM. Both enzymes were highly stable over a broad pH range from pH 5.0 to 9.0 with KGM. The use of the Cel5M enzyme together with the wild-type P. carotovorum HG-49 strain showed significant improvement when compared to using the mere strain HG-49 for application in ramie degumming. Moreover, the whole P. carotovorum Cel5M gene was over-expressed in P. carotovorum HG-49 itself to improve the ramie-degumming capacity. Altogether, this study indicates that in situ production of processing enzymes could be utilized in the textile industry. [ABSTRACT FROM AUTHOR]

Alginate scaffold with high porosity has great potential in the field of tissue engineering due to its biocompatibility and degradability. However, the poor mechanical performance of pure alginate scaffold has limited its use in many applications. Cellulose nanofibers (CNFs) have attracted attention as reinforcing agents to fabricate composite scaffolds with alginate. In this paper, CNF obtained from raw ramie fibers was incorporated with sodium alginate to make a composite scaffold by the freeze-drying method. CNF contents of 0.025, 0.05, 0.1, 0.2, 0.4, 0.8, and 1.6% were selected to study the effect of CNF on scaffold characterization. The composite scaffold exhibited fewer pores but more compact structure than the pure alginate scaffold. Fourier transform infrared spectroscopy was used to study the changes in the functional groups between the ramie fiber and its CNF, pure alginate scaffold, and the composite scaffold. X-ray diffraction indicated that the crystallinity of scaffold increased with addition of CNF. The mechanical performance of scaffold was successfully improved by adding CNF, but the porosity and swelling ratio were decreased. Hence, by combining CNF with alginate, the porous structure, mechanical properties, and swelling behaviors could be tailored, which could expand its use in the field of tissue engineering. [ABSTRACT FROM AUTHOR]

Pectinase plays a crucial role in ramie bio-degumming. A pectate lyase gene (pel 4J4) from the high-efficiency degumming bacteria Dickeya dadantii DCE-01 of bast fibers was cloned and connected to pET28a, and then the recombinant plasmid was successfully transformed into Escherichia coli BL21(DE3). The pectate lyase (Pel4J4) induced was purified by ultrafiltration and Sephadex G-100 gel chromatography. The enzymatic properties of Pel4J4 were studied in detail. pel 4J4 (GenBank accession number: KC900167) had a sequence length of 1179 bp, encoding 392 amino acids. The extracellular pectate lyase activity of pET28a- pel -BL was up to 204.4 IU/mL. The optimal temperature and pH of the purified Pel4J4 were 55℃ and 8.5, respectively. The stable temperature and pH of Pel4J4 activity were 45℃ and 8.5–10.0, respectively. The catalytic activity is Ca2+ dependent and promoted by 1 mmol/L Zn2+, Fe3+, Ca2+, and NH4+, but seriously inhibited by Cu2+ and Pb2+. The optimal substrate is citrus pectin with more than 85% esterification. The heat-resistant alkaline Pel4J4 could strongly degrade natural ramie pectin, indicating a promising application prospect in ramie bio-degumming. [ABSTRACT FROM AUTHOR]

Xylanase plays an important role in the hydrolysis of hemicellulose and has gained much attention in the field of biological degumming. The research for xylanases with cellulase-free and high activity for biological degumming has intensified in recent years. In the present research, heterologous expression of a novel endo-β-1,4-xylanase (GH30) from Dickeya dadantii DCE-01 in Escherichia coli BL21 (DE3) was reported. Biochemical characterization of the enzyme and a potential application in ramie biological degumming was discussed. The results showed that the xylanase gene consists of 1251 nucleotides, belonging to glycoside hydrolase family 30 (GH30). The optimal activity of the xylanase was observed at 50℃ and a pH value of 6.4. The Km and Vmax values for beechwood xylan were 14.25 mg/mL and 296.6 μmol/mg, respectively. The catalytic activity was enhanced by addition of 1 mM Cu2+, Ca2+, Mg2+, and K+. The recombinant enzyme was specific for xylan substrates. The enzyme exhibited hydrolytic activity toward ramie hemicellulose. The recombinant xylanase could be effectively applied to ramie degumming. [ABSTRACT FROM AUTHOR]

Oxidative degumming with hydrogen peroxide provides an efficient pathway and new alternative for natural fiber extraction. In this work, the oxidized cellulose introduced into ramie fibers during the oxidative degumming process was systematically characterized in terms of x-ray photoemission spectroscopy, nuclear magnetic resonance, Fourier transform infrared spectroscopy and scanning electron microscopy. The differences of chemical components, chemical shift, surface structure and surface morphology were analyzed and compared within oxidized cellulose fibers with different oxidation degrees. In addition, the relationship between oxidized cellulose contents and mechanical properties of degummed fibers were further discussed. The results show that the number of oxidized groups increases with increasing oxidation. In addition, the greater presence of oxidized cellulose contributes to a larger loss of tenacity, breaking elongation, flexibility and degree of polymerization in degummed fibers. This study could offer useful information in better understanding the reaction characteristics of oxidative degumming and better control of degummed fiber quality. The contents of oxidized cellulose in ramie fibers could be an effective indicating factor to demonstrate oxidative degumming efficiency and fiber properties. [ABSTRACT FROM AUTHOR]

Sodium hydroxide is commonly used as the main alkali source in the oxidation degumming of ramie in the current studies for natural fiber extraction. However, due to the strong alkalinity of sodium hydroxide, the oxidation reaction speed of hydrogen peroxide is difficult to control and thus results in great damage to the treated fibers. In this paper, magnesium hydroxide was selected as an effective sustained-release alkali source to improve the tensile properties of degummed fibers and reduce the chemical oxygen demand (COD) values of degumming wastewater. This novel reagent can adjust and buffer pH values in the degumming solution. The chemical components and structure properties of degummed fibers were characterized by Fourier transform infrared spectroscopy and X-ray diffraction, respectively, and the as-developed oxidation degumming solution performance was monitored by an oxidation–reduction potentiometer. The results showed that the optimal substitution rate of magnesium hydroxide was 20% during the oxidation process. Compared with the degummed fibers without magnesium hydroxide, the tenacity, work of rupture and degumming yield of treated fibers increased by 39.82%, 46.15% and 5%, respectively. Moreover, the COD values of wastewater decreased by 20% at the same time. [ABSTRACT FROM AUTHOR]

A new method of automatically identifying ramie and cotton fibers using analysis of shape, color, texture, and surface stripes is here introduced. The shape, color, texture, and stripe features of the fibers were extracted by transformation from red, green, blue images to hue saturation intensity images and then to grayscale and binary images, by segmentation of the fiber from background, by edge detection of the outline of fibers, and by stripes on the surface of the fiber. Eighteen characteristic parameters suitable for identification were selected according to their probability distribution curves. A three-layer multilayer perceptron artificial-neural-network-based prediction system is here presented as a means of distinguishing cotton fibers from ramie fibers. The system training was carried out using a back propagation algorithm. The proposed system was tested on more than 2000 cotton and more than 2000 ramie fibers. The experimental results showed that the overall tolerance for false identification of cotton or ramie fiber was under 5%. [ABSTRACT FROM AUTHOR]

In this paper, anthraquinone was used to improve the properties of ramie fiber in oxidation degumming. The chemical components, structure properties, tensile properties of degummed fiber and the character of oxidation degumming solution were tested and analyzed. With the optimal dosage of anthraquinone (2% (o.w.f.)), the content of hemicellulose, the yield of degumming process, polymerization degree and the work of rupture of the degummed fiber were improved by 17.3%, 7%, 2% and 41%, respectively. The oxidation reduction potential (ORP) value of the degumming solution was also tested, with the addition of anthraquinone, and the ORP value decreased by 250 mV, which is of benefit for the properties of fiber. [ABSTRACT FROM AUTHOR]

A new iodine blue staining technique to distinguish ramie fibers from cotton fibers was presented. The influencing factors on staining color, including temperature, concentration of iodide anions in I2-YI solution, ratio of the volumes of added I2-YI solution and saturated LiX solution, time, and concentrations of alkali metal cation Y+ and halide anion X–, were investigated to maximize the difference in color between stained cotton and ramie fibers. The optimum conditions were as follows: temperature: –15℃; concentration of iodide anion in colorant: 1/5; volume ratio: 1/20; colorant: I2-LiI solution; swelling reagent: saturated LiCl solution. The experimental results showed that the new staining technique can be useful for automatic identification of cotton and ramie fibers. [ABSTRACT FROM AUTHOR]

Wool, cotton and ramie thermal properties are qualitatively studied by temperature-dependent Fourier transform infrared (TD-FTIR) spectroscopy, and quantitatively investigated by thermogravimetry coupled with a differential thermal analyzer (TG-DSC). TD-FTIR results indicate that although cotton, ramie and wool exhibit significant water loss, they have no detected degradation within the temperature range from 25℃ to 210℃. These data are confirmed by TG-DSC analysis. Dynamic mechanical thermal analysis provides comparative study of cotton, ramie and wool bundles’ dynamic mechanical thermal properties. The four-fiber-bundle has a much lower storage modulus due to its larger fiber contact surface and twisting deformation; heating reduces the storage modulus significantly for cotton and ramie instead of wool fiber bundles in the temperature range from 25℃ to 100℃. Key E′-T and tan δ-T curve information reveals that ramie fiber bundles have the strongest temperature sensitivity, while wool fiber bundles express the weakest temperature sensitivity. [ABSTRACT FROM AUTHOR]

Ramie, which is one of the most important natural fibers, possesses distinctive characteristics and excellent properties. In this study, the chemical compositions of hemicelluloses in ramie fibers were thoroughly investigated. The effect of NaOH treatment on polysaccharides in hemicelluloses and the effect of polysaccharides on fiber properties were systematically explored. It was found that the components of galactoglucomannan, glucomannan, and xylan accounted for about 79.0% of total weight in ramie hemicelluloses. Galactoglucomannan was more easily soluble than glucomannan in 1% (w/w) NaOH solution. Xylan possessed the lowest solubility in the same concentration of NaOH solution compared to the other two. Furthermore, with an increase of galactoglucomannan, glucomannan, and xylan contents, the fiber linear density and unseparated fiber percentage showed an increasing trend, while the fiber tenacity exhibited a decreasing trend under the same conditions. In addition, it was demonstrated that the contents of these three components have an insignificant effect on friction coefficient, breaking elongation, modulus, and resilience of ramie fibers. This study could provide useful information in understanding the nature of hemicelluloses and polysaccharides within natural fibers, as well as theoretically guiding the degumming process of ramie fibers. [ABSTRACT FROM AUTHOR]

Oxidized cellulose can be produced from the oxidation reaction of hydrogen peroxide in the degumming process of ramie fibers. In this work, the contents of aldehyde and carboxylate groups in ramie cellulose which occurred during the degumming process were quantitatively determined by the electric conductivity titration method. The morphological changes and chemical components of oxidized cellulose were characterized using SEM, XRD, and FT-IR. Additionally, the relationship between the contents of the oxidized groups and the mechanical properties of the degummed fibers were discussed and analyzed. Results showed that the presence of aldehyde and carboxylate groups in the cellulose contributed significantly to the loss of tenacity, breaking elongation, softness, and degree of polymerization of degummed fibers. When the aldehyde content varied from 20 to 35  µmol/g and the carboxylate content varied from 140 to 180 µmol/g, respectively, raw fibers could achieve desired and reasonable degumming results. This study could offer useful information in obtaining optimal operation parameters for ramie oxidation degumming and better control of fiber quality. The degree of oxidation and content of oxidized cellulose could be used as effective indicating factors to demonstrate oxidation degumming efficiency and fiber properties. [ABSTRACT FROM AUTHOR]

This research contributes to the study of prickle sensation in terms of single fiber bending modulus and flexural rigidity, which are important factors for fabric-evoked prickle for garment tactile comfort. In this study, a novel technique was used to study the flexural buckling behavior of single fibers using an axial fiber-compression-bending analyzer (FICBA). The bending behavior and bending equivalent modulus of different single fibers were measured and analyzed. The bending properties of single fibers were quantified by calculating the equivalent bending modulus, and the flexural rigidity via measurement of the protruding length (l), diameter (d) of single fiber, and its critical force (Pcr), obtained from the peak point of the force–displacement curve. The experimental results indicate that ramie single fiber has the highest bending modulus, while cotton has the lowest bending modulus. However, hemp, jute, wool, flax, and cashmere fiber have bending modulus values lower than ramie but higher than cotton. On the other hand, the flexural rigidity of jute fiber is higher than that of wool followed by ramie, hemp, flax, cashmere, and cotton consecutively. Therefore, jute, wool, and ramie are stiffer than the other fibers, especially jute fiber. Thus, jute, wool, and ramie are uncomfortable single fibers because the fabric-evoked prickle, which is caused by short, coarse, and stiff fibers protruding from the fabric surface, generate sufficient force to evoke a low level of activity on a human nociceptors, but insufficient to penetrate the human skin so as to cause itchiness. [ABSTRACT FROM PUBLISHER]

In this study, a mechanical model was introduced to analyze the hair wrapping via a contact surface in the yarn formation zone. Worsted and ramie/cotton rovings were then used to produce yarns on an experimental ring frame with and without a delivery rubber roller to validate the theoretical analysis. Yarn properties, including hairiness, unevenness, and tensile properties were tested and the results indicated that the delivery roller could stop fibers from escaping from the twisting process in the spinning triangle and wrap most of them onto the stem of the yarn. In particular for worsted spinning, yarn unevenness CV, as well as tensile properties, was improved significantly due to an improved arrangement of the worsted strand when using the front delivery rubber roller. However, yarn evenness and tensile properties deteriorated for ramie/cotton yarn spun with a delivery rubber roller. This was mainly because of the high modulus of the ramie/cotton blend strand, as upstream twists were blocked and a weak spinning zone was formed to incur an unexpected drawing. [ABSTRACT FROM PUBLISHER]

Mechanical properties of woven ramie fabric under 3D loadings are fundamental to optimizing the design of woven composites that are frequently subjected to complex stress states. This work proposes a novel 3D test analysis system for evaluating woven natural-fiber fabrics under multidimensional loads. The effects of different loading directions, uniaxial (X direction), biaxial (X and Y), bursting (Z direction), and 3D loading (X, Y, and Z) on the breaking strength of the woven ramie (Boehmeria nivea) fabric were compared. Weft breaking strength was lower than that of warp under uniaxial tension. Variability in warp and weft increased in biaxial tension. Bursting strength was significantly affected by the type of loading head used, with an R20 spherical head producing the highest strength values. Warp and weft were positively correlated under biaxial tension, r = 0.58. The synergistic effect of bursting strength accounted for 12.5% of the total correlation under 3D loadings. [ABSTRACT FROM PUBLISHER]

A novel chemical degumming process for ramie fiber was developed, using sodium carbonate solution with poly(vinyl alcohol) (PVA) as an auxiliary surfactant and sodium triphosphate. Optimum performance for the degumming of ramie fiber was obtained with sodium carbonate concentration 30 g·L —1, PVA concentration 2.2 g·L— 1, sodium triphosphate concentration 6.0 g·L— 1 and temperature 90 °C. The tensile properties of the ramie fibers degummed using Na2CO3 are comparable with fibers degummed using sodium hydroxide. This new mild, rapid degumming technique for ramie fiber has a potential application in industry, and is less environmentally polluting than the traditional method. The ramie fibers before and after degumming were characterized by FT-IR, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. [ABSTRACT FROM PUBLISHER]

Based on the analysis of stripes on fiber surfaces, a new method for cotton and ramie fiber identification is introduced in this paper. The stripes of a fiber surface were extracted by segmentation, edge detection, and thinning, and then they were orthogonally projected along the curving skeleton of the fiber. In addition, six characteristic parameters for identification were obtained, and based on the method of maximum probability, equations for identification were established on the six probability distribution curves of the characteristic parameters. Finally, weight coefficients of the equations were obtained from self-adapting identification tests. The experiments showed that the overall tolerance for false identification of cotton or ramie fiber was under 7%. [ABSTRACT FROM AUTHOR]

This paper introduces a new fiber imaging system that can automatically capture a series of microscopic fiber images in the longitudinal view to form a panoramic image of long-fiber segments for reliable identifications of blended fibers. The panoramic image shows thumbnails of long fibers without missing or duplicating any segments on the sample slide. Firstly, the sample slide is scanned quickly in the X- and Y-axes to capture sequential images of fibers and to register the locations of each image. Secondly, a panoramic image is formed by stitching the sub-images together according to their positions. Thirdly, the panoramic image is analyzed to calculate the skeletons of long-fiber segments, which provide simple representations of fiber shapes and locations, and to register the locations of individual segments for the second scan of the slide. Finally, the triaxial motorized stage transports the slide to the location of each registered segment, readjusts the focus, and captures high quality images for the formal analysis. The entire capturing process is fully automated, and the panoramic view permits efficient image capturing for the reliable identification of ramie and cotton mixed fibers. [ABSTRACT FROM AUTHOR]

Noise can be reduced by sound barrier materials, and transmission loss (TL) measurements are used to determine the insulation performance of sound barriers. In this paper, TL of the non-woven composites with two surface layers and three base layers was measured and analyzed using Brüel and Kjær impedance tubes and Pulse software. The results show that non-woven composites with activated carbon fiber (ACF) nonwoven as a surface layer had significantly higher values of average TL than glass fiber-surfaced composites in both the low frequency range (100-1600 Hz) and the high frequency range (1600-6400 Hz). Regarding the sound barrier performance, base non-wovens made of cotton and ramie were better than polypropylene-based non-wovens in the whole frequency range, while at the low frequencies, especially below 600 Hz, glass fiber-surfaced non-woven was better than ACF-surfaced nonwoven. The composite with cotton non-woven as a base and ACF as a surface exhibited the highest average TL value of 8.56 dB and the lowest mass per unit area of 106 g/m². [ABSTRACT FROM AUTHOR]

Noise absorption is one method for noise reduction in engineering. The material acoustic property for noise absorption is principally based on the efficiency of material structures for damping sound wave reflections. In this paper, three non-woven composites with activated car- bon fiber (rayon precursor) non-woven as a surface layer and cotton, ramie, and polypropylene fiber non-wovens as base layers were produced. Their noise absorption coefficients were measured using the Brüel and Kjær impedance tube instrument and compared to those of three glass-fiber-surfaced non-woven composites. Statistical significance of the differences between the activated carbon fiber composites and glass-fiber-surfaced composites was tested using the method of Duncan's grouping. The study concluded that the activated carbon fiber composites exhibited an exceptional ability to absorb normal incidence sound waves, The analysis also revealed that the activated carbon fiber composite with a cotton base layer would be 4.6 times lighter in weight, 14% higher in low-frequency absorption, and 7% higher in high-frequency absorption, in comparison with the composite having a glass fiber surface layer and a polypropylene fiber base layer. [ABSTRACT FROM AUTHOR]

An analysis of ramie-acrylic blends of different blend compositions is reported using an infrared technique. Blend estimations are made from a calibration plot between the absorption of the 2235 cm[sup-1] band (C≡N) and the composition percentages of acrylic fibers. [ABSTRACT FROM AUTHOR]

Presents a study which examined the tensile strength loss of mercerized and crosslinked ramie fabric. Methods; Results and discussion; Conclusions.

The volume swelling of several textile fibers of plant origin at different moisture conditions has been studied by determin ing their true densities in a density-gradient column. Although the fibers contained different amounts of cellulose, hemi cellulose, and lignin, a simple relation between moisture regain and volume swelling was obtained in all cases. Porosity of the fibers, as estimated from their apparent and true densities, indicated that those having high cellulosic content were less porous than those with high noncellulosic contents. Respective porosities of the fibers did not change significantly with increasing swelling. [ABSTRACT FROM PUBLISHER]