The properties of flax fiber reinforced wood flour/high density polyethylene composites

Flax fiber(FF) was used to reinforce wood flour/high density polyethylene composites(WF/PE).WF/PE particles were uniformly mixed with FF via high-speed mixing and then extruded with a single screw extruder to prepare FF reinforced WF/PE composites(FF/WF/PE).Mechanical testing,dynamic mechanical analysis,scanning electron microscopy(SEM),creep measurement and Torque rheology were used to characterize the resulting composites.The results indicate that the mechanical performance of the composites could be remarkably improved by adding a limited amount of FF.The flexural strength and modulus increased by 14.6 and 51.4%,respectively(FF content of 9 wt%),while the unnotched impact strength could be increased by 26.5%(FF content of12 wt%).The creep resistance and toughness of thecomposite was markedly improved without changing the plastic content of the composite material.

Functional flax fiber with UV-induced switchable wettability for multipurpose oil-water separation

The large number of oily wastewater discharges and oil spills are bringing about severe threats to environment and human health.Corresponding to this challenge,a functional PAA-ZnO-HDTMS flax fiber with UV-induced switchable wettability was developed for efficient oil-water separation in this study.The developed flax fiber was obtained through PAA grafted polymerization and then ZnO-HDTMS nanocomposite immobilization.The as-prepared PAA-ZnO-HDTMS flax fiber was hydrophobic initially and could be switched to hydrophilic through UV irradiation.Its hydrophobicity could be easily recovered through being stored in dark environment for several days.To optimize the performance of the PAA-ZnO-HDTMS flax fiber,the effects of ZnO and HDTMS concentrations on its switchable wettability were investigated.The optimized PAA-ZnO-HDTMS flax fiber had a large water contact angle(∼130°)in air and an extremely small oil contact angle(∼0°)underwater initially.After UV treatment,the water contact angle was decreased to 30°,while the underwater oil contact angle was increased to more than 150°.Based on this UV-induced switchable wettability,the developed PAA-ZnO-HDTMS flax fiber was applied to remove oil from immiscible oil-water mixtures and oil-in-water emulsion with great reusability for multiple cycles.Thus,the developed flax fiber could be further fabricated into oil barrier or oil sorbent for oil-water separation,which could be an environmentally-friendly alternative in oil spill response and oily wastewater treatment.

Effect of Stacking Sequences on the Mechanical and Damping Properties of Flax Glass Fiber Hybrid

The aim of this study is to show the interest of the mechanical and dynamical properties of glass-flax hybrid composites.Therefore,various staking sequences of glass-flax hybrid composites were manufactured and tested in free vibrations.The damping coefficients were identified by fitting the experimental responses of free-free bending vibrations.The obtained results show that the staking sequences and the position of flax fiber layers in the hybrid composites changed the properties,so a classification of different stacking sequences was established.In fact,the hybrid laminate made of two glass external layers placed on both sides of four flax layers is very interesting in term of its mechanical and damping properties.Indeed,it showed better specific bending modulus and loss factor than glass composites with proportions of 31 and 39%,respectively.A study of a structure of this composite has been made to validate the obtained results.

Potassium Influence NRA、HPA and PODA on Leaves of Fiber Flax

The effecf of potassium fertilizer on Nitrate Reductase Activity (NRA), Hydrogen Peroxide Activity (HPA),Peroxidase Activity (PODA) in the fiber flax was studied on campus of NEAU in 1995 and 1996. The result showed that the changing of NRA,HPA and PODA was same in the period from the quick growth to blossom period in the different treamets. NAR and HPA was the highest in the quick growth period then cut down gradually,and PODA was just right contrary. The other side,it was obviously different to NRA, HPA and PODA in the different Potassium levels. NRA and HPA presented the highest enzyme activity in the trea- ment of K2O 22.5kg·ha-1 PODA in creased gradually with the increase of Potassium. PODA was the high- est in the treament of K2O 67.5kg·ha-1. But all of the Potassium treatments was higher than CK whatever NRA,HPA and PODA. Potassium may enhanced the primary stem yield and fiber percentage and lead to fiber yield rising.

The Manufacture of Structured Flax/Hemp Fiber Thermoplastic Composites and Its Flexural Properties

Flax and hemp fibers were used as reinforcing materials to commingle with polypropylene(PP)fiber to realize the mixture of two materials at the stage of yarn.Meanwhile,PP filaments were introduced to produce a core-spun yarn with flax/PP as core and PP filament as outer sheath.The commingled yarns were woven into 2D fabric which was used as the prefabricated material.The composite laminates were prepared by hot press technology.The effects of manufacture technology,yarn structure,and fiber weight fraction on flexural properties of composites were investigated.

亚麻纤维水泥基复合材料研究现状及发展展望

亚麻纤维具有断裂强度高、伸长变形小、弯曲性好、扭转刚度大等特点,因此亚麻纤维水泥基复合材料是一种应用前景广阔的土木工程材料。从亚麻纤维物理化学性质、亚麻纤维对水泥基复合材料性能的影响、亚麻纤维水泥基复合材料性能改善方法3个方面系统阐述了亚麻纤维水泥基复合材料的研究现状与存在问题。提出未来发展趋势:加强用亚麻纤维替代聚丙烯纤维制备水泥基复合材料;揭示潮湿情况下亚麻纤维水泥基复合材料性能演变规律;在三轴应力、潮湿条件耦合作用下构建亚麻纤维水泥基复合材料力学损伤模型;从增加亚麻纤维本体强度、改善亚麻纤维和水泥基材料界面黏结性角度来提高亚麻水泥基复合材料的应用性能。

Balanced Fertilization Improves Fiber Yield and Quality of Winter Flax (<i>Linum usitatissimum</i>L.)

Winter fiber flax has been planted in a large area in Yunnan Province, the southwestern part of China, and other areas of the world, but little is known about the influence of fertilization on the fiber yield and quality. For that, a two-factor experiment in random block designed was carried out by specifying nitrogen (N), phosphorus (P) and potassium (K) as factor A, boron (B), manganese (Mn), copper (Cu), zinc (Zn) and molybdenum (Mo) as factor B each in four levels and their complete combinations. With the increase of N, P and K fertilizers, the yields of long-fiber and total-fiber obviously increased resulting from the increased straw yield, although the portion of retted-stem in straw, contents of longfiber and total-fiber decreased. The fiber tensile strength and flexibility increased as well. The micronutrients application increased the yields of straw, long-fiber and total-fiber, but gave no influence to fiber content and the fiber qualities. Combinations of the macronutrients and micronutrients gave obvious influences to the yields of straw and fiber, contents of long-fiber and total-fiber, fiber fineness and tensile strength, but little influence to the fiber flexibility. The fertilizers formula A2B2, i.e. N-P2O5-K2O 172.8, 28.8 172.8 kg/hm2, Zn-Cu-B-M-Mo 2363, 1654, 236, 2363,165 g/hm2, was the best, yielding most in the straw, long-fiber and total-fiber, with synchronous improvement of the three quality indices.

染整工艺对麻纤维抗菌性能的影响

从麻纤维自身形态结构、化学组成出发,分析了影响麻纤维自身抗菌性的因素。概述了染整加工工艺中脱胶、染料种类和染料助剂对麻纤维抗菌性能的影响,总结了麻织物的物理抗菌整理和化学抗菌整理方式。认为:在麻纤维自身具备抗菌性的基础上,采用添加天然抗菌剂、物理抗菌整理、植物染料染色等方法,可有效降低麻纤维生产加工过程中抗菌成分的流失,进一步提高麻织物的抗菌性能。

纤维表面改性对PLA/Flax复合材料性能的影响

目的研究纤维表面改性对复合材料结晶、热稳定性、动态力学性能、尺寸稳定性、吸水率等的影响。方法采用碱、碱+马来酸酐、碱+KH550这3种处理方法对纤维表面进行改性,通过熔融挤出与聚乳酸(PLA)混合制备聚乳酸/亚麻纤维(PLA/Flax)复合材料。结果亚麻纤维经表面改性后使PLA更容易发生冷结晶,结晶结构更加致密、完善,PLA/Flax尺寸稳定性优于PLA。纤维的加入提高了PLA的吸水率,但热稳定性能有所降低。纤维表面改性降低了PLA/Flax的储能模量。结论碱+KH550处理纤维与PLA共混所得复合材料的结晶性、尺寸稳定性最佳,为高性能PLA/Flax复合材料的制备提供了一定的实验及理论依据。

亚麻植物纤维与树脂动态润湿及其表面浸润粗糙水平分析

分析了作为复合材料增强体使用的天然亚麻植物纤维的动态润湿过程,观测了植物纤维及其预浸渍纤维纱线表面形貌,探讨植物纤维与不同液体体系(去离子水,环氧树脂)的润湿特征,并与使用广泛的玻璃纤维动态润湿过程进行比较。基于Wilhelmy法,通过在极低速率下建立纤维与树脂动态润湿系统及浸润力学模型,结合流场函数和表面轮廓中线平均算术偏差粗糙度理论方法,运用方差分析技术提出了定量判断增强体纤维表面固有粗糙水平的新方法。分析探讨了亚麻植物纤维和玻璃纤维与浸润液体的粘附功。结果表明:作为复合材料增强体,亚麻植物纤维表面粗糙因子更大,亚麻植物纤维动态润湿过程润湿力、粘附功较小,同等条件下,相比玻璃纤维具有较差的润湿性能。

超临界CO_(2)协同复合酶对胡麻纤维脱胶技术研究

为实现胡麻纤维的高效提取,采用超临界CO_(2)技术与生物酶浸渍技术相结合对废弃胡麻秸秆进行脱胶处理。通过响应面设计对超临界CO_(2)处理时间、处理温度、处理压力进行优化。以纤维残胶率、质量损失率、断裂强力、纤维直径和细度为检测指标,利用正交试验研究超临界CO_(2)辅助酶脱胶工艺参数和脱胶效果的关系,并与传统化学脱胶、复合酶脱胶、单纯超临界CO_(2)脱胶工艺进行比较。结果表明:超临界CO_(2)处理压力为18 MPa、处理温度为64℃、CO_(2)流量为20 g/min、复合酶用量为8%(owf)(木聚糖酶∶β甘露聚糖酶∶果胶酶质量比为4.4∶2.3∶1.3),处理时间40 min超临界CO_(2)辅助酶脱胶最佳工艺。对比其他工艺,发现经超临界CO_(2)体系处理的胡麻纤维残胶率较小(14.45%),对纤维素的损伤小,较大程度保留了纤维强力(47.56 cN),基本满足纺纱要求。

Production of Pectinolytic Enzymes by Two Bacillus spp. Strains and Their Application in Flax Degumming

This study demonstrated that Bacillus licheniformis HDYM-03 and Bacillus megaterium HDYM-09, isolated from a liquid sample of fl ax retting pool, were able to produce pectinolytic enzymes using polysaccharides as substrates. Bacillus megaterium HDYM-09 produced pectin lyase that exhibited the highest activity of 2116.71 ± 11.55 U/mL. Bacillus licheniformis HDYM-03 produced pectate lyase that exhibited the highest activity of 611.21 ± 14.54 U/mL. Based on these fi ndings, we constructed four retting systems to degrade the pectin substance. The results showed that the content of galacturonic acid in the mixed system was 529.21 μg/mL, the content of reducing sugar was 98.14 mg/mL, and the weight loss ratio of cells reached 19.49%, which were signifi cantly higher than those in other systems. The mixed system has more advantages, and the utilization rate of degumming was higher, which further ensured that the degumming can be carried out effi ciently and quickly. The mixed system exhibits feasible applications in the fi ber and textile industry.

基于漆酶/TEMPO体系的亚麻脱胶探究

为推进亚麻纤维的绿色化生产,将漆酶介体系统应用于亚麻机落的脱胶,并引入EDTA增强系统的脱胶效果。文章通过对漆酶/TEMPO脱胶系统中温度、pH值、浴比、时间、漆酶质量浓度、TEMPO质量浓度进行探究,确定了在温度55℃、pH值4.0、浴比1︰20、脱胶时间4 h、漆酶质量浓度1.5 U/mL,TEMPO质量浓度为0.2 g/L的条件下,漆酶/TEMPO体系对木质素的去除效果最好。并在此条件下,辅助添加20 mmol/L的EDTA,脱胶后亚麻表面非纤维素物质明显减少,可观察到单根纤维状态,木质素去除率可达56.74%,且纤维无明显损伤,强力基本保留。

Adhesion of Silica Particles on Thin Polymer Films Model of Flax Cell Wall

The present work is focused on better understanding of the interfacial interactions of SBA-15 mesoporous silica particles with flax fibers. In order to overcome the inherent complexity of flax fiber surface composition we have prepared model polysaccharide surfaces representing the main component of the flax fibers, e.g. cellulose, polygalacturonic acid (PGUA), and xyloglucan (XG) with thicknesses of about 200 nm, 100 nm, and 110 nm, respectively. The ξ-potential measurements of both silica and polysaccharides were performed in aqueous solutions as a function of pH and ionic strength. ξ-potential, AFM and SEM results supported the important role of electrostatic interactions in the silica adsorption on polysaccharide surfaces, since silica adsorption increased remarkably with ionic strength. The adsorption density of the SBA-15 onto the various polysaccharides was Cellulose > PGUA > XG, and the maximum was observed at pH = 4. Urea used as hydrogen bonds breaker reduced significantly the adsorption of SBA-15 on the polysaccharide surfaces, which highlighted the significant contribution of hydrogen bonding in the adsorption process. It was observed that most adsorbed SBA-15 particles were resistant to ultrasonic washing, which revealed their strong irreversible adsorption. Finally, direct adsorption experiments on both raw and treated real flax fibers yielded results consistent with those of model surfaces showing the important role of the surface fibers treatments on the improvement of the interfacial adhesion of the silica particles with flax fibers. The remarkable affinity of the SBA-15 particles with treated flax fibers is encouraging to design superinsulators composites with tuneable mechanical performances.

亚麻短纤维增强硅橡胶复合材料的力学性能

为了提升亚麻短纤维增强硅橡胶复合材料的力学性能,以亚麻短纤维作增强体,硅橡胶为基体,制备了亚麻短纤维/硅橡胶复合材料。研究了亚麻短纤维的长度和用量对复合材料拉伸弹性模量的影响。结果表明,不同长度和用量的亚麻短纤维对硅橡胶基复合材料的补强作用不同;当亚麻短纤维的体积分数为1.26%、长度为2.5 mm时,复合材料的拉伸弹性模量最高,断裂应变最低。工业生产中,可以通过控制亚麻短纤维的长度和含量对硅橡胶基体进行补强达到不同的效果。

生物柴油给油工艺对棉型亚麻纤维性能的影响

为改善亚麻纤维的可纺性,研究了生物柴油对棉型亚麻纤维给油的最佳工艺。采用喷洒方式对棉型亚麻纤维进行给油处理,利用纤维摩擦系数仪测试纤维动、静摩擦因数,对油剂用量、养生温度、养生时间等因素进行单因素试验。使用SPSS软件研究各因素对纤维动、静摩擦因数的显著性影响,再利用Design-Expert试验设计软件进行响应面设计,得到了生物柴油对棉型亚麻纤维给油的最佳工艺。结果表明,油剂用量以及养生温度对纤维动、静摩擦因数具有显著性影响;最佳给油工艺:油剂用量为2.05%、养生时间24 h、养生温度41.7℃,该工艺下纤维平滑性最好,纤维与纤维间、纤维与金属间动摩擦因数分别为0.245、0.203;纺纱试验表明生物柴油给油工艺相较于矿物油给油工艺纺制的亚麻纯纺纱,断裂强度以及伸长率分别提升了4.3%、4.41%,条干CV值降低了6.07%,同时千米细节、千米粗节以及千米麻粒均有所降低。

氧化脱胶体系对亚麻纤维理化性能的影响

尽管亚麻纤维的氧化脱胶技术因高效环保受到研究者的广泛关注,不同氧化体系脱胶制得纤维理化性能的差异尚未有系统报道。本文采用碱性过氧化氢、过碳酸钠、TEMPO体系及NHPI体系四种氧化体系进行亚麻纤维的脱胶。结果表明:四种氧化体系均能成功实现亚麻纤维的脱胶,脱胶后纤维的残余木质素含量分别为1.29%、1.74%、1.62%、1.42%,残余果胶含量分别为1.09%、1.58%、1.34%、1.67%,聚合度分别为1 268、2 315、1 086、572,束纤维强度分别为49.14、63.09、39.08、24.41 cN/tex,线密度分别为10.41、15.72、8.33、10.32 dtex。可见,NHPI体系制得的纤维强伸性能较差且残余果胶含量较高;TEMPO体系制得的纤维线密度较佳,但残余木质素含量较高且聚合度较低;过碳酸钠体系制得的纤维强伸性能最佳,但残余木质素及残余果胶含量较高;碱性过氧化氢体系制得的纤维则残余胶质含量最低。

不同加热速率下亚麻纤维的热解机理

为了研究亚麻纤维在高温下的热解机理,首先对纯亚麻纤维在非等温条件下的热解动力学行为进行了分析.完成了4种加热速率下的热重实验,研究了亚麻纤维的热解特性,采用6种无模型法和2种模型拟合法计算了亚麻纤维热解反应活化能随转化率的分布,判断了不同热解反应阶段的反应模型类别.结合动力学补偿效应分析,重建了亚麻纤维主要热解阶段的反应机理函数.通过模型独立性分析,对各重建函数的准确性进行了评估.通过质谱对亚麻纤维的热解生成物进行了归纳.结果表明,亚麻纤维热解的主要反应阶段可视为一个独立的子反应,其温度区间位于半纤维素、纤维素等主要成分的热解温度范围内.该阶段的反应机理与F类模型比较接近.重建的反应模型函数表现出较高的拟合度且具有较好的准确性.亚麻纤维的主要热解生成物包含烯烃和醛等11种有机化合物.

低温等离子体预处理对混杂纤维复合材料性能的影响

为了提高纤维与基体不饱和聚酯界面的结合强度,利用低温等离子体技术对纤维表面进行预处理,探讨了低温等离子体预处理对混杂纤维(亚麻纤维与玄武岩纤维)复合材料性能的影响.SEM分析表明,改性后的玄武岩纤维、亚麻纤维表面与基体界面之间的结合强度增大.FTIR分析表明,低温等离子体预处理产生的-C-OH、-C-O、-COOH和-COO-含氧基团提高了纤维与基体之间界面的结合强度.力学测试试验结果表明,PB/F、PB/PF和B/PF的弯曲和冲击性能明显提高,B/PF的弯曲强度比未处理的B/F提高40.5%,PB/PF、B/PF的冲击韧性比B/F提高116%.混杂纤维复合材料表现出较好的弯曲和冲击性能.

环氧树脂/CF/亚麻纤维复合材料电磁屏蔽性能

电子电气设备等产生电磁辐射污染会严重影响到人体健康,并干扰设备的正常运行,解决电磁污染的关键是使用电磁屏蔽材料。采用模压工艺制备了具有电磁屏蔽功能的环氧树脂/碳纤维(CF)/亚麻纤维复合材料。借助矢量网络分析仪、热重分析仪、万能试验机、扫描电子显微镜(SEM)等研究CF粉对复合材料的电磁屏蔽性能(EMI SE)、热稳定性和力学性能的影响。结果表明,复合材料的弯曲强度随着CF粉含量的增加而增加,并在其质量分数为30%时达到最大值,为102.5 MPa,与未加CF的材料相比较,提高了31.1%,此后进一步增加CF粉含量,复合材料的弯曲强度开始下降。SEM证实,复合材料力学性能的提高来源于CF与环氧树脂界面性能的改善。CF粉的加入提高了环氧树脂/亚麻纤维复合材料的热稳定性,热分解温度从206℃提高到268℃。同时复合材料的体积电阻率随着CF粉含量的增加而下降,从0.65Ω·cm降至0.132Ω·cm。在8.4~12.4 GHz电磁波范围内,环氧树脂/CF/亚麻纤维复合材料的EMI SE达到20 dB以上,基本满足商业要求。