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.     

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.     

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.     

The Hybrid Effect of Jute/Kenaf/E-Glass Woven Fabric Epoxy Composites for Medium Load Applications: Impact,Inter-Laminar Strength,and Failure Surface Characterization

This research has been carried out to find better hybrid natural/glass fiber-reinforced composites for engineering applications. This research work studied the impact and inter-laminar strength of E-glass with jute/kenaf woven fabric epoxy composites with the aim of evaluating the hybridization effects on different laminate stacking sequences made with jute, kenaf, and E-glass fabrics by the vacuum bagging method. All the laminates were prepared in 300 × 300 mm² with a total of five plies maintained at 3 mm thickness, by varying the number and position of jute, kenaf, glass layers so as to obtain nine different stacking sequences. Among them, one group of all pure jute, pure kenaf, and pure E-glass laminates were also fabricated for comparison purpose. The specimen preparation and testing were carried out as per ASTM standards. From the results, it is shown that the properties of jute/kenaf fabrics-reinforced epoxy composites can be enhanced by hybridization with the addition of glass fabrics. The hybridization of jute/kenaf fabrics with E-glass fabrics provides a method to improve the mechanical impact and inter-laminar strength over pure natural fiber-reinforced composites. The hybrid laminate having E-glass and kenaf fiber plies as skin layers and jute fiber plies as core layers showed better properties compared to other laminates.     

罗布麻微波-超声波脱胶工艺的研究

文章针对罗布麻胶质含量高,脱胶比较困难的特点,介绍了-种新型的脱胶方法,即利用微波预处理、低频超声波和高频超声波相结合的方法对罗布麻进行脱胶处理.分析了罗布麻脱胶前后胶质的变化和精干麻的品质指标.实验表明,该脱胶方法能明显改善罗布麻纤维的品质,充分分离麻纤维束,并且是一种环境友好的脱胶方法.通过有无微波预处理的实验表明,微波预处理能够提高罗布麻超声波脱胶效果.     

罗布麻的生物酶脱胶与精梳

对罗布麻开发中的生物酶脱胶工艺及罗布麻精梳工艺进行了分析。指出开松的原则是“低速度、慢开松、小密度”;分离的关键是离心力的大小,必须考虑终末速度和腾空速度;梳理成形则应采用完全罗拉式梳理,对麻纤维损伤小。     

Calcium Alginate Foams Prepared by a Microfluidic T-Junction System: Stability and Food Applications

Highly porous alginate foams were prepared via a novel route in which highly viscous alginate solutions were bubbled using a microfluidic T-junction device. The relationship between bubble size and bubbling conditions such as air pressure and solution flow rate was studied, and the ability of the T-junction setup to generate monodisperse microbubbles (mean diameter, ～154 μm) and produce porous foams was systematically investigated. The foams were characterised by optical and scanning electron microscopy. Foams of varying lengths (12–45 mm) were successfully prepared using this technique, with an average density of ～235 kg/m³. The pore diameter within the foams was determined by microscopy to be in the range of 600 nm–200 μm with a mean diameter of ～31 μm. It was concluded that porosity in the foam (>90%) can be varied depending on the initial bubble size. Thus, a possible production method of stable highly porous solid foams for exploitation in food and bioprocess technologies is presented by which products can be made to different sizes.     

An analysis of anterior scleral shape and its role in the design and fitting of scleral contact lenses

Purpose

The purpose of this study was to evaluate the shape of the anterior sclera by measuring the sagittal height and corneoscleral transition angles in the four cardinal and four oblique segments of the eye.

Flax retting by degumming composite enzyme produced by Bacillus licheniformis HDYM-04 and effect on fiber properties

Flax enzymatic retting with composite enzyme produced by microbes with inexpensive substrates is widely researched due to less contamination and lower cost. Bacillus licheniformis HDYM-04, isolated from a liquid sample of flax retting pool, efficiently produced degumming enzymes after 48 h of fermentation with inexpensive konjaku flour, consisted of 587.5 U/mL pectinase, 365.2 U/mL mannanase, and 140.1 U/mL xylanase. Almost half the maximum activity of three above-mentioned degumming enzymes was maintained at pH 4.0–6.0 which demonstrated its stability in pH condition of flax retting. After 120 h of retting with this composite enzyme, scanning electronic microscopy showed more significant reduction in gummy components on the fiber surface than those of water retting. The fiber strength was 182.4 ± 9.3 N, 14.3% higher than water-retted samples. The long fiber rate and fiber yield also verified higher fiber productivity. The results permitted this degumming composite enzyme an applicable potential in flax retting.     

罗布麻生物脱胶工艺模型探讨

1.College of Textile;Donghua University;Shanghai 201620;China;2.Laboratory of New Fiber Materials and Moden Textile;the Growing Base for State Laboratory;Qingdao University;Qingdao;Shandong 266071;China;3.College of Textiles and Fashion;Qingdao University;Qingdao;Shandong 266071;China;4.Shenzhen Import and Export Inspection and Quarantine Bureau;Shenzhen;Guangdong 518045;China     

罗布麻微生物脱胶的菌种筛选与工艺优化

为提高罗布麻微生物脱胶效率,采用透明圈法、DNS比色法以及16S rRNA分子鉴定等方法从新疆乌鲁木齐南山野生麻生长区土壤中筛选优势脱胶菌株,并设计正交试验将所筛优势菌株用于优化新疆罗布麻微生物脱胶工艺参数。试验结果表明:所筛7株菌具有较高果胶酶活、木聚糖酶活,低纤维素酶活,适用于罗布麻微生物脱胶的实际应用;7菌种主要为芽孢杆菌属,此外还有肠杆菌属、克雷伯菌属和泛菌属;在脱胶液pH值为7,浴比为1∶40,摇床转速为90 r/min的最优脱胶工艺参数下,最佳脱胶方式为7菌系复合脱胶,脱胶时残胶率可降至30.45%,脱胶效果改善,同时菌株之间形成稳定的脱胶菌群,脱胶时菌种之间的协同作用、拮抗作用会影响菌群的脱胶能力。     

The response of polymer optical fiber (POF) to bending and axial tension for the application of a POF sensor for automotive seat occupancy sensing

The automotive industry is a promising area for innovations in the field of polymer optical fiber (POF) sensors as the industry currently uses the POF mostly for data transmissions. Since an optical fiber sensor has a high bandwidth, is small in size, is lightweight, and is immune to electromagnetic interference, it offers higher performance than that of its electrical-based counterparts such as the strain gage, elastomeric bladder, and resistive sensor systems. This enhanced performance makes an optical fiber sensor a suitable material for sensing seat occupancy for improved safety features in automobiles. The overall goal of this research is to develop a textile-based optical fiber sensor for automotive seat occupancy with high accuracy and reproducibility. In this study, the bending and tensile loading responses of POF were investigated, where two perfluorinated (PF) graded index (GI) POFs with two different core/cladding diameters, 62.5/750 and 62.5/490 μm, were used. The bending loss and the light attenuation against the applied axial stress were measured by a photon counting optical time-domain reflectometer. The critical bending diameters were analyzed: Cytop-1 (62.5/750 μm)?≥?38.10 mm, Cytop-2 (62.5/490 μm)?≥?44.45 mm. Furthermore, the elastic sensitive strain regions (x), where the stress-induced loss was recoverable, of the POFs at a 76.2 mm gage length at a strain rate of 4 mm/min were determined: Cytop-1: 3% ≤ x ≤ 3.5%, Cytop-2: 3.1% ≤ x ≤ 3.3%. The Cytop-1 was found to be less sensitive to bending and to have greater elastic sensitive strain range relative to the Cytop-2. In this study, a theoretical approach of the PF GI POF behavior to bending and axial tension was provided. The results demonstrated the feasibility of POFs as optical fiber sensors for automotive seat occupancy sensing.     

罗布麻中黄酮的超临界CO2萃取及其抗菌性

为解决传统脱胶工艺罗布麻韧皮纤维中黄酮化合物的浪费问题,对罗布麻韧皮纤维采取超临界脱胶预处理的同时,利用超临界CO2 提取其黄酮有效成分,研究分析影响罗布麻中黄酮萃取的4个主要因素,然后对萃取液进行了高效液相色谱分析和抗菌实验。结果表明：助溶剂主要影响超临界流体的极性,随着助溶剂含量的增加,超临界流体极性的增加提高了黄酮萃取率,但助溶剂含量过高时,过多水分易造成萃取管路堵塞,使黄酮的萃取效率降低;在45 ℃、20 MPa时黄酮萃取率较高,升高或降低压力与温度均会影响黄酮萃取效果;随着超临界CO2流量的增加,黄酮萃取率逐渐增加,但对萃取设备要求更高;罗布麻中黄酮化合物具有良好的抗菌效果,是罗布麻纤维具有抗菌性能的原因之一。     

大麻纤维的芬顿法脱胶及其性能

为减少纺织工业中脱胶废液的强碱强酸造成环境的污染,采用芬顿法对大麻纤维进行脱胶处理。以残胶率、断裂强力、直径、白度及纤维长度为指标,探讨pH值、七水合硫酸亚铁浓度、双氧水浓度和温度对大麻纤维脱胶效果的影响;借助红外光谱仪和X射线衍射仪分析了大麻纤维的化学结构及结晶度变化,通过扫描电子显微镜观察了大麻纤维的脱胶效果。结果表明:最佳脱胶工艺条件为pH值6.0,七水合硫酸铁质量浓度10 g/L,双氧水质量浓度9 g/L,温度80 ℃,此时脱胶纤维残胶率为10.12％,断裂强力为32.453 cN,直径为29.745 μm,长度为 5.62 cm; 芬顿法可有效去除大麻纤维的胶质。     

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.     

红麻粗纱酶解效果测定及其分析

对红麻韧皮纤维经生物酶一浴法脱胶改性处理后,运用咔唑比色法测定红麻粗纱果胶和木质素的残留量,定量测定果胶的去除率。分析了酶浓度、温度、pH值和作用时间对酶解后果胶及木质素去除率的影响。实验表明,复合酶对红麻粗纱中果胶和木质素去除效果较好,所得纤维质量明显改善。     

Comparison of the performance of kenaf fiber using different reagents presoak combined with steam explosion treatment

To enhance the degumming effect of steam explosion on kenaf fiber, different chemical reagents including hydrogen peroxide (H₂O₂), sulfuric acid (H₂SO₄), and sodium hydroxide (NaOH) presoak combined with steam explosion were used and compared in this article. Distilled water coupled with steam explosion treatment and kenaf raw samples were used as control. The fiber morphology, chemical composition, crystalline structure, degree of fineness, and breaking tenacity of kenaf fibers after treatment were studied. The results showed that hydrogen peroxide (H₂O₂) performs better on removing lignin. It not only splits fibers, but also keeps the fiber’s tenacity during steam explosion treatment. Dilute sulfuric acid (H₂SO₄) performs better on hemicellulose removal, but it damages the fiber cellulose during steam explosion treatment and cause the fiber strength decrease a lot. Sodium hydroxide (NaOH) performs the best on removing hemicellulose and lignin, and splits fiber well. However, the breaking tenacity of the fiber is lower than the fiber pretreated by H₂O₂. Besides, NaOH is a pollutant to the environment. In conclusion, H₂O₂ could be considered as the most promising reagent to be used in combined presoak-steam explosion system.     

桑皮纤维的化学提取方法及性能测试

桑皮纤维是一种新型纤维素纤维,具有不同于棉和麻的一些特殊品质。文章采用二煮法对桑皮进行脱胶,制得桑皮纤维,初步探讨了酸、碱在脱胶过程中的作用,以及碱与双氧水同浴脱胶漂白原理。对纤维的形态结构和拉伸性能进行了测试。研究结果表明:桑皮纤维平均长度约23.0 mm,纤维纵向有条纹,截面多为近似椭圆形,无中腔,断裂强度优于棉、麻。     

Characterisation of the porcine eyeball as an in-vitro model for dry eye

Purpose

To characterise the anatomical parameters of the porcine eye for potentially using it as a laboratory model of dry eye.