“闪爆”处理大麻纤维的研究

采用“闪爆”新技术处理大麻纤维,分析了闪爆处理前后大麻纤维脱胶、化学组成和理化性能的变化。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,大麻纤维的的红外光谱也发生了变化,纤维的上染性能明显改善。     

大麻纤维“闪爆”处理脱胶方法初探

采用闪爆处理的方法对大麻进行脱胶处理研究,分析了闪爆方法的作用机理,研究了不同闪爆条件对原麻处理的作用效果。结果表明,闪爆能够对原麻中的纤维束产生劈裂作用,去除纤维表面的杂质,并改善纤维表面的微孔隙结构。原麻经闪爆处理后,纤维素含量可由52.94%增加到84.37%,而木质素则由7.15%减少到3.91%;脱胶效果也明显改善,脱胶后残胶率可由14.75%下降到2.41%,脱胶时间也大大缩短;闪爆处理后纤维的上染速率明显加快;而纤维的密度和聚合度由于热压和冲击波的作用有所下降。     

双氧水预浸/蒸汽闪爆红麻纤维脱胶工艺及性能

为提高红麻纤维分散度,用双氧水(H_2O_2)预浸与蒸汽闪爆联合脱胶,通过单因素实验确定最优H_2O_2预浸/蒸汽闪爆工艺,对纤维微观形态、成分及结晶度进行了分析.结果表明,最佳脱胶条件为H_2O_2浓度0.6 mol/L,预浸时间1 h,闪爆压力1.2 MPa,闪爆保压时间60 s.该条件下脱胶后的纤维细度可达180公支,断裂强度为5.2 c N/dtex,均比用蒸馏水预浸/蒸汽闪爆工艺增加1倍.H_2O_2预浸/蒸汽闪爆可有效去除半纤维素、木质素等非纤维素物质,纤维表面光滑洁净,纤维素未被破坏,且结晶度增加.     

新型再生纤维素纤维的生产工艺、结构及性能

简述了从NaOH水溶液中通过湿纺技术制得的新型纤维素纤维的原料的处理工艺、纤维结构和性能。通过蒸汽闪爆蒸煮,从木浆可制得碱可溶纤维素,在4℃下可溶于9.1wt%的NaOH水溶液中。通过湿法纺丝技术,从该溶液中可制得具有良好性能的新型纤维素及其织物,性能测试结果表明,这一新型纤维具有良好的柔软性、耐磨性、抗起皱性和尺寸稳定性,是传统粘胶纤维的最佳替代品,其性能／价格比甚至优于NMMO溶剂纺纤维。     

欧洲大麻纤维的组成结构及脱胶研究

大麻纤维的品质既取决于原麻品质,又与其脱胶工艺息息相关。原麻纤维会因产地不同而带来化学成分含量等的不同,因而将欧洲大麻与其他产地,包括黑龙江、六安及东营的大麻纤维的化学成分、形态和聚集态结构进行了对比,并采用超声波-微波工艺对欧洲大麻进行了后续的脱胶研究。结果表明:原麻品质方面,欧洲大麻的纤维素含量较高,与东营大麻的纤维素含量相差无几,木质素含量最低;脱胶工艺方面,经超声波预处理后的欧洲大麻纤维的微波最佳脱胶工艺为碱液浓度为10 g/L、微波时间为50 min,最终大麻纤维的胶质去除率和残胶率分别为77.45%和7.50%。     

分次闪爆对棉秆皮纤维结构和性能的影响

为了提升棉秆皮的分离效果,提出了一种简便、有效的分次闪爆的棉秆皮分离方式。研究了延长保压时间闪爆和分次闪爆的纤维表面形貌差异以及分次闪爆次数对棉秆皮纤维结构、性能和分离效果的影响。结果表明,分次闪爆法提高了高温高压水蒸气喷射对棉秆皮纤维分离的作用,减少了高温对纤维的损伤。分次闪爆最佳次数为3次,所得纤维得率为32.45%,长度47.7 mm,细度50.4 dtex,长径比726.9,纤维素含量68.5%,断裂强度2.2 cN/dtex;纤维分离效果好,可用于复合材料。     

蔗渣闪爆处理及其黄原酸化物的制备和应用

采用热蒸汽适度闪爆及稀碱洗涤等预处理技术对蔗渣进行纯化和活化,利用处理后的蔗渣纤维素合成纤维素基黄原酸酯,对其在水处理中的应用进行了研究。研究优化了闪爆处理的工艺条件,并采用IR、SEM和化学分析技术对闪爆前后蔗渣纤维的形态、结构、a-纤维素的含量进行了分析,对处理前后的蔗渣纤维的碱化和黄原酸化合成条件进行了优化。结果表明,闪爆预处理技术是一种便宜、迅速、无污染的技术,蔗渣纤维素基黄原酸酯对含金属离子的污水有良好的处理效果。     

棉纤维蒸汽闪爆改性及其化学反应性能

研究采用高压热蒸汽闪爆技术,对棉纤维进行物理改性,并对闪爆前后棉纤维形态、溶解度、聚合度分析表征。通过改性前后棉纤维合成羧甲基纤维素研究发现,闪爆改性后其反应性能有大的提高。     

剑麻纤维蒸汽爆破处理研究

采用蒸汽爆破处理技术处理剑麻纤维,分析阐述了蒸汽爆破处理过程及原理。通过化学分析方法及扫描电镜、红外光谱、X—射线衍射等现代分析手段分析蒸汽爆破处理前后剑麻纤维化学组分和形态结构的变化。结果表明,蒸汽爆破处理技术能够实现剑麻纤维各组分的有效分离,减少杂质成分,提高纤维素含量;同时,蒸汽爆破处理能改善剑麻纤维的形态结构,提高化学试剂的可及度,改善化学反应性能。     

织物处理工艺对苎麻纤维增强复合材料力学性能的影响

选取了几种不同处理工艺制作的苎麻织物,分别对比其化学组成、单丝拉伸性能,以及对比苎麻纤维增强复合材料的力学性能,最终找到最佳的增强材料用苎麻纤维织物的处理方法。结果表明:苎麻纤维被处理的越细,对纤维的力学性能损伤就越大;省去去毛以及漂白工艺,可以使复合材料力学性能有一定程度的提高;生物酶脱胶处理工艺对环境影响更小,而且与化学脱胶相比,纤维的力学性能和复合材料的力学性能基本持平。     

Effect of steam explosion on degumming efficiency and physicochemical characteristics of banana fiber

A steam explosion degumming method coupled with the 16 (4⁴) orthogonal array design was used to investigate the efficient retting of fibers. Four parameters were examined to determine the residual gum and lignin content of retted fibers, and the optimum extraction conditions were determined to be the following: banana fiber moisture content of 10%, 1.2% NaOH, steam pressure of 1.75 MPa, and residence time of 90 s. Under optimized conditions, the experimental yield of residual gum (5.47 ± 0.22%) and lignin (3.78 ± 0.12%) agreed closely with the predicted yield. The chemical composition of the fibers was analyzed, and the retted fibers exhibited an increase in the cellulose content and a decrease in the lignin and hemicellulose contents. This result was further confirmed by XRD and Fourier transform infrared spectroscopy. The scanning electron microscopy analysis of the treated fibers showed a change in their surface morphology compared with that of the raw fibers. Their thermal characterization showed an enhanced thermal stability of the retted fibers compared to the raw fibers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40598.     

The Degradation of Lignin,Cellulose, and Hemicellulose in Kenaf Bast Under Different Pressures Using Steam Explosion Treatment

The study of the main chemical composition degradation, especially cellulose degradation at high temperatures and within high moisture environments, provides important information that can guide biomass processing using steam explosion (STEX) and other similar treatments. In this paper, kenaf bast was treated using STEX at pressures of 0.5, 1.0, and 1.5 MPa. The chemical composition change and the infrared spectra were investigated. The crystalline index and degree of polymerization of kenaf cellulose were also quantified. It was found that pectin and hemicellulose could be easily degraded with the STEX treatment, while lignin only exhibited slight decomposition; cellulose degraded at 1.5 MPa STEX treatment on the kenaf. Research also indicates that cellulose with a low molecular weight can be removed with a low-pressure STEX treatment. By coupling STEX with chemical degumming process, the high-quality kenaf fiber with 7.12% residue gum content and 134.5 Nm fineness can be obtained.     

Surface and interface characterization of untreated and SMA Imide-treated hemp fiber/acrylic composites

The hydrophilic nature of natural fibers adversely affects adhesion to a hydrophobic matrix, and consequently it may unfavorably influence the strength of the composite. Therefore, modifying the fiber or the matrix is essential to obtain optimum composite properties. In this work, hemp fibers were modified applying a paper sizing technique using SMA Imide resin (copolymer of styrene and dimethylaminopropylamine maleimide) as a surface modifying agent. The performance of the hemp/acrylic composite was improved significantly using the treated fibers. Inverse gas chromatography (IGC) and pull-out test were employed to study the hemp fiber/matrix interface and the surface characteristics of untreated and treated hemp fibers. The IGC results demonstrated that treated fibers had slightly higher dispersive force compared with untreated fibers. Moreover, modification of fibers with SMA Imide resin slightly decreased the basic character and significantly increased the acid character of hemp fibers. From the pull-out test, the average stress to pull the SMA-treated fibers out was 71% higher than that calculated for untreated fibers. The higher interfacial strength for the treated fibers shows that the SMA treatment had a beneficial influence on the adhesion of the acrylic resin to the hemp fibers. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers     

Effect of fiber modification with a novel compatibilizer on the mechanical properties and water absorption of hemp‐fiber‐reinforced unsaturated polyester composites

Hemp‐fiber‐reinforced unsaturated polyester (UPE) composites were prepared by compression molding. The treatment of hemp fibers with N‐methylol acrylamide (NMA) and sulfuric acid as a catalyst significantly increased tensile strength, flexural modulus of rupture and flexural modulus of elasticity, and water resistance of the resulting hemp–UPE composites. Fourier transform infrared (FTIR) spectra revealed that some NMA was covalently bonded to hemp fibers. Scanning electronic microscopy graphs of the fractured hemp–UPE composites revealed that treatment of hemp fibers with NMA greatly improved the interfacial adhesion between hemp fibers and UPE. The chemical reactions between hemp fibers and NMA as well as the mechanism of improving the interfacial adhesion were proposed and discussed. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Chemical modification of hemp fibers by silane coupling agents

Natural hemp fibers were chemically modified using silane coupling agents to reduce their hydrophilic character. The existence of a chemical bond between coupling agents and hemp fibers was confirmed by ATR‐FTIR spectroscopy, ²⁹Si Nuclear Magnetic Resonance (NMR), thermogravimetric analysis (TGA), energy dispersive spectroscopy (EDS), and BET surface area measurements. It was shown that the initial concentration and the chemical structure of the organosilane coupling agent have an effect on the grafted quantity on the hemp fiber surfaces. The grafted quantity increased proportionally to the initial concentration of silane molecules. The presence of polar amino end group (NH₂) in silane structure can cause an increase in the grafted quantity, compared with results obtained in the case of silane molecules containing methacryloxy groups. This effect is attributed to the formation of hydrogen bonds between NH₂ and unreacted hydroxyl groups of hemp fibers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

EFFECT OF HARVESTING AGE ON THE CHEMICAL PROPERTIES OF HEMP PLANTS

ABSTRACT

With the increasing scarcity of available forest for harvesting, there is a potential need for alternatives to wood fibers for pulp and paper production. Hemp is considered to be a good source of long and strong fibers. In this study, the effect of the harvesting age of hemp stems on their chemical composition and the biomass produced by the plants were studied. Hemp stems were harvested at ages of 30, 60, 90, and 120 days. Standard TAPPI procedures were used for chemical analyses of the stems. There was little variation observed in the percentage of the constituents such as lignin, hemicellulose, and α-cellulose with the plant growth. However, a very significant decrease was seen in the percentages of extractives, ash, and silica with plant growth. The rate of increase of biomass was higher in the first half of the growing period, i.e., from 30 to 60 days, compared to the second half, from 60 to 90 days. On the basis of the chemical constituents and the biomass produced, it is concluded that hemp grown for the pulp and paper industry should be harvested between 60 and 90 days for optimal results.