蒸汽爆破处理对剑麻纤维组分分离的影响

采用高温、高压水蒸汽瞬间爆破处理剑麻纤维。通过处理前后剑麻纤维的水溶物、碱溶物、木质素含量、纤维素含量的比较,分析研究了蒸汽爆破处理条件对剑麻纤维组分分离效果的影响。试验结果表明:爆破前预处理、处理温度(压力)、维压时间是影响组分分离的重要因素:随着处理强度的增大,纤维中木质素含量降低,纤维素含量增大;爆破前的不同试剂预浸泡处理中,质量分数为17.5％的NaOH和质量分数为0.1％的H2SO4预浸泡处理效果较优,水和质量分数为1％的NaOH浸泡处理效果较差。      

物理改性处理对菠萝皮渣膳食纤维物化特性的影响

以菠萝皮渣为原料制备膳食纤维,考察超微粉碎、蒸汽爆破和挤压膨化3种物理改性方式对菠萝皮渣膳食纤维的基本成分、理化性质、形貌结构及生物活性物质溶出量的影响。结果表明:3种物理改性方式均能提高样品阳离子交换能力,增加多酚、黄酮物质的溶出量。其中蒸汽爆破处理能显著提高可溶性膳食纤维含量,在持水持油性方面表现良好。形貌结构分析结果显示,改性后的膳食纤维结构均发生不同程度的变化,但其主要成分及化学结构未受影响。综上所述,蒸汽爆破处理有助于改善菠萝皮渣膳食纤维的品质。     

新鲜椰衣纤维表面半纤维素含量的测定及去除

新鲜椰衣纤维表面粘附有一定量结构疏松的椰糠,椰糠的主要成分为半纤维素和木聚糖类,既不利于椰衣纤维的改性,也不利于用做固定化酶的载体材料,必须将其除去。采用稀硫酸加热水解,使新鲜椰衣纤维表面粘附的半纤维素转化为可溶的木糖和低聚木糖,以木糖为标准,3,5-二硝基水杨酸(DNS)为显色剂,采用分光光度法间接测定新鲜椰衣纤维中半纤维的含量,以考察椰衣纤维表面半纤维去除的效果。结果表明,当硫酸溶液浓度1.3 mol/L、水解温度102℃、水解时间2 h,固液比为1∶50时,半纤维素的去除效果最佳,新鲜椰衣纤维表面粘附的半纤维素量为14.58%,通过红外光谱和扫描电镜等可观察椰衣纤维表面的变化,重现性试验及标准回收试验证明该方法效果良好。      

不同椰衣栽培介质对西瓜苗生长及生理特性的影响

研究不同的椰衣栽培介质对西瓜发芽的影响等，对于开展椰衣栽培介质基质化的应用具有重要意义。采用海南3市(县)5镇的11种椰糠为基础及配置2种(MIX1、MIX2)复合基质为测试材料，对椰衣介质13个处理的浸出液分别进行西瓜种子发芽实验、西瓜苗生长实验及相关生理测评等。结果表明：复合基质处理能保证西瓜苗生长，pH、EC值的大小是筛选优良椰衣复合基质的关键。椰衣介质MIX1处理是适宜西瓜生长发育的复合基质。     

椰园/牧草间作:主间作物之间相互的影响

进行了椰园间作牧草生态系统的研究。通过不同类型椰园间作不同品种牧草的适应性试验,观测了不同主间作物栽培方式中椰园根系分布、土壤养分与温度、主间作物生长及产量等方面的变化。结果表明:(1)在种植密度为10m×6m的椰园(相对光照强度约在50%以上)中,禾本科和豆科牧草均能正常生长;在8m×6m的椰园(相对光照强度约在30%左右)中,多数牧草品种能正常生长;在6m×6m的椰园(相对光照强度不足30%)中,只有少数禾本科牧草能基本正常生长。(2)禾本科牧草与椰树组成的系统稳定性比豆科牧草的好。(3)间作物一般应距幼树1m、成龄树2m以外的地方种植。(4)合理压青培肥与科学防治金龟子害虫,有利于加强主间作物生态系统的稳定性。      

蒸汽爆破预处理降解香蕉茎秆纤维素组分的研究

分析测试香蕉茎秆总固体含量(TS)和挥发性固体含量(VS)及香蕉茎秆固体剩余物中纤维素、半纤维素、木质素含量;采用蒸汽爆破法对香蕉茎秆进行预处理,探讨不同压力及维压时间下对香蕉茎秆中半纤维素、纤维素、木质素组分的降解程度,分析蒸汽爆破预处理优缺点。试验结果表明,经过蒸汽爆破预处理后,香蕉茎秆的组分被不同程度破坏,当压力为3.5 MPa,维压时间为4 min时,香蕉茎秆中半纤维素含量由预处理前13.33%降至4.36%,降解率高达67.29%,纤维素含量由48.33%降至39.15%,降解率为18.99%,木质素含量由14.62%降至6.52%,降解率为55.40%,总体含量由76.28%降至50.03%,降解率为34.41%。说明蒸汽爆破技术对香蕉茎秆固体剩余物的预处理效果比较显著,有一定的优越性。     

椰园/牧草间作:牧草的适应性研究

进行了15种热带牧草在椰园间作的适应性试验,调查了它们的产量情况和生产参数并作统计分析。结果表明:在幼龄椰园内,间作豆科牧草和禾本科牧草,均可获得较高的经济产量;在光照强度大于30％的成龄椰园内,可间作多数禾本科牧草,并能获得一定的经济产量,但不宜间作豆科牧草;在光照强度低于30％的成龄椰园内,不宜于绝大多数牧草问作。间作于幼龄椰园的牧草产值可达1.0~3.0万元/hm2;间作于成龄椰园的禾本科牧草产值可达0.5～2.0万元/hm2。      

不同碱煮处理对棉秆皮纤维结构形态的影响

借助于JSM-5800电子扫描显微镜对棉秆皮纤维的外观形态结构、不同碱煮处理下的形态结构进行观察分析。棉秆皮纤维素纤维属工艺纤维,纤维表面不光滑,存在着沟槽。在碱处理过程中,单根工艺纤维的分裂出现不同时性,在一根工艺纤维上存在分叉现象。在高温长时间的碱处理中,棉秆皮纤维发生脆性断裂,但是纤维外观结构形态不变化。     

1984—85年硬质纤维的回顾与展望

展 望 1984年世界剑麻产量有所回升,1985年继续增产。1984年初巴西因长期干旱导致剑麻产量下降的局面已告结束,但东非的恶劣天气仍然继续存在。1984年菲律宾的蕉麻由于遭到连续的台风损害,致使1985年产量减少。尽管椰子收成较差,但椰衣纤维和椰衣纱条的生产,估计没有多大变化。 1984年干草收成好,与此同时,1983/1984年度消费国剑麻储备减少,生产国的剑麻纤维和剑麻制品的出口量也许不会下降。蕉麻的需要量明显增加,而出口量不足,价格又很高。印度国内椰衣纱条和椰衣纤维产品的消耗量大大增加,1983年所有硬质纤维制品的生产国出口利润总额达到3.03亿美元,1984年有可能进一步增加,但这种情况1985年也许不会再出现。     

胶乳手套的防粘技术发展现状

目前胶乳手套的防粘技术有4种:⑴用粉末或液体处理表面;⑵表面的化学处理;⑶用聚合物在手套表面涂覆;⑷用助剂进行改性。以上4种防粘技术能较好地改善手套的穿戴性能;手套表面的化学处理及用配料进行改性,为手套表面接枝改性创造了条件。      

Flexural characteristics of coir fiber reinforced cementitious composites

This study has examined the flexural properties of natural and chemically modified coir fiber reinforced cementitious composites (CFRCC). Coir fibers of two different average lengths were used, and the longer coir fibers were also treated with a 1 % NaOH solution for comparison. The fibers were combined with cementitious materials and chemical agents (dispersant, defoamer or wetting agent) to form CFRCC. The flexural properties of the composites, including elastic stress, flexural strength, toughness and toughness index, were measured. The effects of fiber treatments, addition of chemical agents and accelerated ageing of composites on the composites’ flexural properties were examined. The results showed that the CFRCC samples were 5–12 % lighter than the conventional mortar, and that the addition of coir fibers improved the flexural strength of the CFRCC materials. Toughness and toughness index, which were associated with the work of fracture, were increased more than ten times. For the alkalized long coir fiber composites, a higher immediate and long-term toughness index was achieved. SEM microstructure images revealed improved physicochemical bonding in the treated CFRCC.     

Effect of temperature and durations of heating on coir fibers

Biocomposites derived from polymeric resin and lignocellulosic fibers may be processed at temperatures ranging from 100 °C to 230 °C for durations of up to 30 min. These processing parameters normally lead to the degradation of the fiber's mechanical properties such as Young's modulus (E), ultimate tensile strength (UTS) and percentage elongation at break (%EB). In this study, the effect of processing temperature and duration of heating on the mechanical properties of coir fibers were examined by heating the fibers in an oven at 150 °C and 200 °C for 10, 20 and 30 min to simulate processing conditions. Degradation of mechanical properties was evaluated based on the tensile properties. It was observed that the UTS and %EB of heat treated fibers decreased by 1.17-44.00% and 15.28-81.93%, respectively, compared to untreated fibers. However, the stiffness or E of the fibers increased by 6.3-25.0%. Infra red spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were used to elucidate further the influence of chemical, thermal and microstructural degradation on the resulting tensile properties of the fibers. The main chemical changes observed at 2922, 2851, 1733, 1651, 1460, 1421 and1370 cm⁻¹ absorption bands were attributed to oxidation, dehydration and depolymerization as well as volatization of the fiber components. These phenomena were also attributed to in the TGA, and in addition the TGA showed increased thermal stability of the heat treated coir fibers with reference to the untreated counterparts which was most probably due to increased recrystallization and cross linking. The microstructural features including microcracks, micropores, collapsed microfibrils and sort of cooled molten liquid observed on the surface of heat treated coir fibers from the scanning electron microscope (SEM) could not directly be linked to the effect of temperature and durations of heating although such features may have largely account for the lower tensile properties of heat treated coir fibers with reference to untreated ones.     

Preparation and characterization of micro- and nano-fibrils from jute

In order to prepare micro- and nano-fibrils from jute, the binder has to be cleaned off. A new technique including chemical (room temperature alkaline, acid steam, and 80 °C alkaline) and physical (high pressure steam) treatments of natural fibers was developed. The effects of chemical and physical treatments on the morphological development of jute fibers from micro- to nano-scale were observed by using scanning electron microscopy (SEM). This novel natural fibers treatment technology has two advantages compared with others. One is the long strands of natural fibers keep their length by special acid steam treatment, but the traditional acid solution treatment makes the length of natural fibers short. Another one is the high pressure steam treatment that made jute fibers nano-fibrils. The thermal property of untreated and treated fibers was determined by using thermogravimetric analysis (TGA) which indicated that the thermal stability of the jute fibers was enhanced after treatments. The lignin acted as binder was mainly removed by analyzing solid residues using fourier transform infrared spectrometer (FTIR).     

Effect of ionizing and non-ionizing preirradiations on physico-mechanical properties of coir fiber grafting with methylacrylate

Coir fibers were modified with methyl acrylate (MA) mixed with methanol (MeOH) under thermal curing method at different temperatures (40?C80 °C) for different curing times (20?C60 min). A series of solutions of different concentrations of MA in methanol along with 2 % benzoyl peroxide, were prepared. Monomer concentration, curing temperature, and curing time were optimized with the extent of grafting of monomer and mechanical properties of cured fiber and found to be 30 % MA, 60 °C and 40 min curing time registered as better performance (Grafting (Gr) = 5.7 %, tensile strength (TS) = 72 %, elongation at break (Eb) = 88 %) than those of untreated fiber. For further improvement of the properties, untreated coir fibers were pretreated with gamma and UV radiations at different doses and then pretreated fibers were soaked in the optimized monomer and cured under optimum conditions. Coir fiber pretreated with UV radiation and grafted with optimized monomer showed the best properties such as Gr (7.12 %), TS (132 %), and Eb (153 %) over raw fiber. Water uptake and simulated weathering test of untreated and treated coir fibers were studied.     

Steam explosion pretreatment reproduction and alkaline delignification reactions performed on a pilot scale with sugarcane bagasse for bioethanol production

This work was focused on the steam explosion pretreatment reproduction and alkaline delignification reactions on a pilot scale for the ethanol production, through different varieties of natural sugarcane bagasse, pretreated bagasse and delignified pretreated bagasse (cellulosic pulp). The possible chemical composition differences of the various types of bagasse, as well as the chemical composition variations of the materials in the 20 processes of pretreatment and delignification on the pilot scale were verified. The analytical results of the 20 samples of most diverse varieties and origins of natural sugarcane bagasse considering planting soils, planting periods and weather; show no significant chemical differences. It is evident that only with the chemical composition it is not possible to verify the differences between the varieties of sugarcane bagasses. The research results may offer some evidences of these varieties, but it is not a reliable parameter. The pilot process of steam explosion pretreatment and the alkaline delignification process of pretreated material showed through analytical results a good capacity of reproduction, as the standard differences were below 2.7. The average allowed in the pretreatment and alkaline delignification processes were 66.1 ± 0.8 and 51.5 ± 2.6 respectively, ensuring an excellent reproduction capacity of the processes obtained through chemical characterizations.     

基于离散元法的椰糠颗粒建模及仿真参数标定

为确定椰糠在离散元模拟过程中合理的仿真参数,本文基于离散元法Hertz-Mindlin（no slip）接触模型在仿真软件EDEM 2018中建立椰糠颗粒模型并生成颗粒工厂,通过测量比对物理试验和仿真试验椰糠堆积角的方法对其仿真参数进行标定。首先通过物理试验测得椰糠堆积角、堆积密度等本征参数,利用EDEM 2018内嵌GEMM数据库以及相关文献,综合分析得到椰糠待标定因素的高低水平;然后进行Plackett-Burman试验设计筛选出对椰糠堆积角影响显著的因素依次为：椰糠-椰糠静摩擦系数、椰糠-椰糠滚动摩擦系数和椰糠剪切模量;再进行Box-Behnken试验设计建立堆积角与3个显著性影响因素的回归模型,运用Design expert软件优化功能,以堆积角物理试验45.69°为目标,对回归方程寻优求解,得到显著性影响因素最佳组合：椰糠剪切模量为1.44 MPa,椰糠-椰糠静摩擦系数为1.11,椰糠-椰糠滚动摩擦系数为0.15;最后通过试验验证表明此组合参数可用于椰糠物料的离散元仿真,能为椰糠输送、混合等机械装备的设计研发提供理论参考。     

“闪爆”处理对大麻脱胶及纤维性能的影响

采用“闪爆”新技术来处理大麻纤维，分析了闪爆处理前后大麻纤维脱胶、化学组分和理化性能的变化：结果表明，“闪爆”后的大麻纤维经水洗处理后，纤维素的比率显著增加，木质素等非纤维素成分明显降低，而且脱胶效果理想，大麻纤维的红外光谱闪爆处理以后在1510cm-1处吸收峰和在1736cm-1处吸收峰趋于消失，纤维的上染性能明显改善.     

Macro-micro structure,antibacterial activity,and physico-mechanical properties of the mulberry bast fibers

In this paper, the mulberry fibers were successfully obtained by a new pretreatment named alkali-assisted microwave plus biological enzymatic technique (AMBET). The morphology, microstructure, physico-mechanical and antibacterial properties of the mulberry bast fibers were investigated by means of scanning electron microscope (SEM), Fourier Transform-Infrared (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), instron tensile tester and antibacterial testing. The results showed that impurities of the bast fibers could be removed by AMBET treatment. AMBET treated mulberry fiber was even, smooth and fine, and typical cellulose I in the mulberry fibers was confirmed by FTIR and XRD analysis. The crystallinity of the AMBET treated fibers was higher than that of the raw mulberry and chemical treated mulberry fibers. Thermal analysis indicated that the mulberry fibers had a good thermal stability. Moreover, the AMBET treated mulberry fibers showed excellent antimicrobial activities against S.aureus. The physical properties of the mulberry fibers indicated the AMBET treated mulberry fibers were ideal candidates for new textile materials.