Effect of Planting Density and Fertilizer Application on Fiber Yield of Ramie (Boehmeria nivea)

As the most important cultural practices for ramie （Boehmeria nivea） production, the single effects of plant density and nitrogen （N）, phosphorus （P）, potassium （K） fertilization on yield are well documented. To achieve the high yield and quality of ramie fiber, it is principal to quantify the fertilizer dosage for ramie sustainable production. A central composite design （CCD） was adopted with three replications, for a two-year field experiment （2008-2009） in the Yangtze River Valley of China. The aim was to evaluate both the individual and combined effects of plant density and N, P, and K fertilization on yield and fiber quality. The effects of the four factors on yield and quality of ramie cultivar Huazhu 4 were tested. Then mathematical models of the relationship among the four factors affecting ramie production and quality were established and analyzed to optimize the four factors, and used to establish optimum cultivation methods for the elite cultivar suitable to this area of the Yangtze River Valley. Supplements of N （X2）, P 0（3） and K 0（4）, and the density （X0 with N （X2） interaction significantly influenced strength in tests of mature ramie. The influence on fiber yield in the two year tests by the four factors ranked as follows： X3〉X4〉X~〉X2. We established the optimization technique attaining yield of 2 600 kg ha-~ in the tests as following： density of 28 350-31 650 plants ha-1, and supplements of N, P and K of 363-387, 98.58-105.48 and 280.20- 319.8 kg ha-1, respectively. It was concluded that nitrogen mostly improved plant growth and fiber yield while potassium had discernible effects on fiber quality.

Mechanical and Thermal Properties of Apocynum and Ramie Fiber Mat Reinforced Polylactic Acid Composites

With the increasing awareness of environmental protection and rational utilization of resources,natural fiber reinforced composites have shown broad development prospects.Apocynum fiber,known as the“king of wild fiber”,not only has moisture absorption,air permeability,and good mechanical properties but also has many health-related advantages such as antibacterial properties.In this study,four types of needle-punched Apocynum fiber and ramie fiber mat reinforced polylactic acid(PLA)composites were fabricated.Mechanical and thermal properties of the composites were tested and analyzed.The results showed that compared with those of the ramie fiber finish needle-punched mat reinforced composites,the tensile strength and the tensile modulus of Apocynum fiber finish needle-punched mat reinforced composites had increased by 15.3%and 60.1%,respectively.In comparison,the bending strength and the bending modulus were decreased by 21.8%and 7.6%,respectively.Moreover,compared with the Apocynum fiber finish needled-punched mat reinforced composites and the ramie fiber finish needle-punched mat reinforced composites,the Apocynum 50/ramie 50 finish needle-punched mat reinforced composites had the best tensile and bending properties.The after-fracture morphology was detected by a scanning electron microscope(SEM).The thermal properties of the composites were also characterized.It was found that the thermal properties of the four types of composites showed very similar behaviors.

Preparation and Properties of Unmodified Ramie Fiber Reinforced Polypropylene Composites

Ramie fiber （RF） was used to reinforce the polypropylene （PP）. The composites were prepared with a melting hybrid technology. Tests had been performed on PP and composites with different RF contents （10 wt%, 20 wt%, and 30 wt%）. By using SEM, DSC, TGA, electronic universal testing machine, HDT-VICAT tester and coefficient of linear expansion tester, the effects of the RF loading were assessed on the basis of morphologies, mechanical and thermal properties as well as vicat softening temperature and CTE of the resulting composites. The results show that the thermal degradation temperature of the PP/RF composites becomes lower with higher fiber content. The crystallization rate of the PP matrix is accelerated by the unmodified RF. Because of the inferior interfacial bonding strength between RF and PP, the tensile strength of composites decreases by the presence of RF. And the RF used is relatively long compared with the diameter, the impact strength of the composites is improved by the unmodified RF. The vicat softening temperature of composites can be increased by about 5℃ in the presence of RF compared with PP. The CTE is reduced significantly in the presence of RF. Generally speaking, impact strength, crystallization rate, vicat softening temperature and CTE of PP/RF composites could be improved in the presence of RF. The tensile strength is decreased and thermal degradation temperature of composites becomes lower, but these should not affect most subsequent normal uses of the composites. As the unmodified RF is used directly, no hazardous waste is produced during the fabrication process, combined with the low price, so, a facile and economic preparation pathway is given by using unmodified natural fiber to reinforce polymer and composites with good performance obtained.

Improvement of Mechanical,Dynamic-Mechanical and Thermal Properties for Noil Ramie Fiber Reinforced Polyethylene Composites

Noil discarded fibers from fiber production for textile industry have short length and are always considered less valuable.Here,noil ramie fibers/HDPE composite is prepared using twin-screw extruder and the dynamic mechanical and thermal properties are studied.The influence of ramie fiber and maleic anhydride-grafted polyolefin(MA-g-PO)on mechanical,dynamic mechanical and thermal properties is investigated.It is observed that the tensile,flexural and impact properties of the composites treated with MA-g-PO are all improved in comparison to the untreated composites.Dynamic mechanical properties of the composite with MA-g-PO show an increase in the storage modulus with a higherαrelaxation peak,together with the micromorphology analysis,indicating an improved interfacial bonding between fiber and matrix by the MA-g-PO addition.Furthermore,the change in TGA thermograms of composite caused by MA-g-PO exhibits that the addition of MA-g-PO is also helpful to increase the thermal stability of noil ramie fiber/HDPE composites.

Comparison of Structures and Properties between Wool and Ramie Fibers Treated by Atmospheric Pressure Ar and Ar/O_2 Plasma

The technique of atmospheric pressure plasma is of value in textile industry.In this paper,argon(Ar)and argon/oxygen(Ar/O2)atmospheric pressure plasma were used to treat wool and ramie fibers.The structures and properties of treated fibers were investigated by means of SEM,XPS,single fiber tensile tester and so on.The results proved that the effects of plasma treatments depended on structural characteristics of fibers to a great extent,besides conditions of plasma treatment.By atmospheric pressure plasma treatment,wool fiber had significant changes in morphology structure,surface chemical component,mechanic properties and dyeability,while ramie fiber just showed a little change.In additional,Ar/O2 plasma showed more effective action than argon.And at the beginning of treatment,plasma brought about remarkable effects,which did not increase with prolonging of treat time.

Optical and Mechanical Properties of Ramie Fiber/Epoxy Resin Transparent Composites

The residual resources of ramie fiber-based textile products were used as raw materials.Ramie fiber felt(RF)was modified by NaClO_(2) aqueous solution and then impregnated with water-based epoxy resin(WER).RF/WER transparent composite materials were prepared by lamination hot pressing process.The composite materials’color difference,transmittance,haze,density,water absorption,and mechanical properties were determined to assess the effects of NaClO_(2) treatment and the number of ramie fiber layers on the properties of the prepared composites.The results showed significantly improved optical and mechanical properties of the RF/WER transparent composites after NaClO_(2) treatment.With the increase of ramie fiber layers,the composites’whiteness,transmittance,and water absorption decreased while the haze increased.For material with three layers,the optical transmittance in the visible light region was 82%,and the haze was 96%,indicating the material has both high transmittance and high haze characteristics.The tensile strength increases with the increase of the number of layers,and the tensile strength of the composite with six layers is 243 MPa.This study broadens the scope of application of ramie fiber as a new option for home decoration materials.

Report on Screening Test of Dazhou Superior Ramie Germplasm Resources

[Objectives]To promote the development of the ramie industry in Dazhou City of Sichuan Province and provide a material basis for the breeding of new ramie varieties.[Methods]The Institute of Bast Fiber Crops of Dazhou Academy of Agricultural Sciences performed a screening test of excellent ramie germplasm resources from 2017 to 2019 to compare the growth,resistance,raw fiber yield and fiber fineness of the experimental materials.[Results]All the experimental materials showed strong growth potential,drought resistance and disease resistance.There were 8 kinds of resources with a fiber fineness greater than 2000 m/g,of which 3 kinds of resource materials had a fiber fineness greater than 2300 m/g;12 kinds of resources has the raw fiber yield exceeding the control and 10 kinds of resources had the raw fiber yield≥2000 kg/ha;3 kinds of resources met the requirements of the high-yield and high-quality indicators(fiber fineness exceeding 2000 m/g and raw fiber yield≥2000 kg/ha),they were BD0718,BD1614 and BYL2.[Conclusions]These high-quality ramie resources can provide a rich resource base for the breeding of new ramie varieties.

Genomic variation,environmental adaptation,and feralization in ramie,an ancient fiber crop

Feralization is an important evolutionary process,but the mechanisms behind it remain poorly understood.Here,we use the ancient fiber crop ramie(Boehmeria nivea(L.)Gaudich.)as a model to investigate genomic changes associated with both domestication and feralization.We first produced a chromosome-scale de novo genome assembly of feral ramie and investigated structural variations between feral and domesticated ramie genomes.Next,we gathered 915 accessions from 23 countries,comprising cultivars,major landraces,feral populations,and the wild progenitor.Based on whole-genome resequencing of these accessions,we constructed the most comprehensive ramie genomic variation map to date.Phylogenetic,demographic,and admixture signal detection analyses indicated that feral ramie is of exoferal or exo-endo origin,i.e.,descended from hybridization between domesticated ramie and the wild progenitor or ancient landraces.Feral ramie has higher genetic diversity than wild or domesticated ramie,and genomic regions affected by natural selection during feralization differ from those under selection during domestication.Ecological analyses showed that feral and domesticated ramie have similar ecological niches that differ substantially from the niche of the wild progenitor,and three environmental variables are associated with habitat-specific adaptation in feral ramie.These findings advance our understanding of feralization,providing a scientific basis for the excavation of new crop germplasm resources and offering novel insights into the evolution of feralization in nature.

苎麻剥制机械研究现状与发展趋势

苎麻是中国特色纤维作物,对其茎秆进行剥制是获取苎麻纤维材料的必要环节,开展苎麻剥制机械研究对该产业发展具有重要意义。文章在综述苎麻茎秆力学性能研究现状的基础上,分析了国外早期剥麻机存在的剥麻质量与效率不高的问题,介绍了我国现有剥麻机械的技术优势与问题,总结了麻类作物剥麻机械仿真模拟及智能机具的研发现状。研究认为,苎麻剥制机具研究还处于发展阶段,自动化、智能化、数据化是其未来研究发展方向。

苎麻新型酶-化学联合脱胶工艺研究

苎麻生物酶脱胶具有节能环保、作用条件温和等优势,但单独生物酶处理得到的精干麻存在残胶率偏高,针对这一不足,从强化螯合剂预处理和碱氧后处理角度出发,以残胶率、蓝光白度、束纤维强度、柔软度和润湿性等为评价指标考察苎麻酶法脱胶效果提升。结果表明:在优化螯合剂预处理(螯合剂5 g/L,90℃保温1 h,浴比1∶15)和碱氧后处理(氢氧化钠4 g/L,TF-122H稳定剂3 g/L,硅酸钠2 g/L,双氰胺1 g/L,30%过氧化氢2 mL/L,98℃保温2 h,浴比1∶15)条件下,苎麻纤维残胶率可以降至4.29%,白度达到63.20%,束纤维强度达到3.55 cN/dtex。与传统化学脱胶工艺相比,新工艺制得的精干麻蓝光白度相近,而束纤维强度、柔软度和润湿性都明显高于传统工艺,残胶率略高。

Flame-retardant Wrapped Ramie Fibers towards Suppressing “Candlewick Effect” of Polypropylene/Ramie Fiber Composites

In this work, a flame-retardant polypropylene（PP）/ramie fiber（RF） composite was prepared. The ramie fibers were wrapped chemically by a phosphorus- and nitrogen-containing flame retardant（FR） produced via in situ condensation reaction so as to suppress their candlewick effect. Fourier transform infrared spectroscopy（FTIR）, X-ray photoelectron spectroscopy（XPS） and scanning electron microscopy（SEM） demonstrated that the ramie fibers wrapped chemically by FR（FR-RF） were obtained successfully. Thermogravimatric test showed that the PP/FR-RF composite had more residue and better thermal stability at high temperatures than the PP/RF composite. Cone calorimeter（CC） results indicated that the peak of heat release rate（PHRR） and total heat release（THR） correspondingly decreased by 23.4% and 12.5% compared with the values of neat PP/RF. The PP/FR-RF composite created a continuous and compact char layer after the combustion. Combining FTIR analysis of char residue after CC test with heat conduction coefficient results, it could be concluded that the charring of FR on RF greatly weakened the candlewick effect of RF, and more char residue in the RF domain facilitated the formation of more continuous and compact char layer in the whole combustion zone, consequently protected PP composites during combustion, resulting in the better flame retardancy of PP/FR-RF composite than that of PP/RF composite.

环保包装专用苎麻品种筛选

根据轻型环保包装材料的苎麻[Boehmeria nivea(L.)Gaudich.]品种要求,2021—2022年对现有国内审定的8个苎麻品种进行农艺性状调查、纤维支数测定、抗性鉴定等研究,筛选出具有中等抗性以上、纤维支数2000公支以上、纤维产量3750 kg/hm^(2)以上的品种苎麻。对抗性、产量、纤维支数综合分析,根据分析结果从8个品种中筛选出中苎1号、赣苎6号、华苎6号3个适宜环保包装专用的苎麻品种。

苎麻落麻纤维增强聚合物复合材料研究

研究了苎麻落麻纤维的基本性能,及其增强酚醛树脂、环氧树脂、不饱和聚酯树脂复合材料的制备工艺和力学性能,并与黄麻纤维布复合材料和玻璃布复合材料性能进行了比较。同时,初步探讨了麻纤维复合材料的应用。

横向喂入式苎麻剥麻机的设计与试验

为解决苎麻纤维剥制劳动强度大、工效低等问题,该文研制了一种大型苎麻剥麻机。采用横向喂入、连续分段加工剥麻原理,设计出样机并进行了剥麻试验和麻样质量检测。试验结果表明,该机剥麻工效为131kg/h,鲜茎出麻率4.15%,达到样机设计指标要求。剥麻样品检测结果表明,苎麻含杂麻1.09%,苎麻含胶率23.28%,苎麻束纤维断裂强度为4.59CN/dtex,均满足国家标准要求。研究结果可为大型苎麻剥制机械的设计提供参考。

苎麻生长期对纤维结构及品质的影响

在不同生长期收割苎麻,然后分别对其纤维结构及品质进行了研究。结果发现,适当地提前收割,苎麻纤维结晶度、取向度减小,木质化程度降低,可改善苎麻织物的刺痒感、柔软性,而且在以后的生产过程中纤维不易脆裂,提高了纤维的导湿、传热等服用性能,并且苎麻纤维的细度大大提高。不仅提高了苎麻原麻的品质,能开发针织产品,而且保持了天然纤维产品的原有特色。

高性能天然纤维复合材料及其制品研究与开发现状

本文分析了麻类纤维和竹纤维的性能 ,指出麻和竹等高性能天然纤维具有复合材料的性能特点 ,可作为复合材料的增强剂 ;综述了国内外高性能天然纤维复合材料及其制品开发应用研究的现状 ,指出了开发研究这类复合材料及其制品的意义 ;最后 ,分析了其市场潜力 ,指出这类复合材料及其制品具有很好的发展前景。

苎麻纤维改性研究进展

综述了苎麻纤维的改性原理以及苎麻纤维碱法、液氨、乙酰化、烷基化、磺化、氰乙基化、离子液体、阳离子、纳米粒子等改性工艺的最新进展,探讨了超临界流体苎麻纤维的改性。

固化温度对苎麻纤维增强复合材料性能的影响

研究了固化温度对苎麻纤维增强复合材料力学性能的影响,同时对比研究了平纹苎麻织物、单向苎麻纤维和单向玻璃纤维增强复合材料的力学性能。结果表明:环氧树脂3233分别在120℃,140℃和180℃固化2h后,其拉伸性能和弯曲性能没有明显的变化;而基于环氧树脂3233的苎麻纤维增强复合材料在120℃和140℃固化2h后力学性能相当,但是在180℃固化2h后,强度明显减小,模量变化不大;单向苎麻纤维增强复合材料的力学性能要远远大于平纹苎麻织物增强复合材料的力学性能,如单向苎麻复合材料uRamie-3233-120的压缩强度和压缩模量分别为154.0 MPa和35.6 GPa,而苎麻织物增强复合材料fRamie-3233-120分别为95.0 MPa和9.2 GPa;玻璃纤维增强复合材料的强度也会高明显高于苎麻纤维增强复合材料的强度。

苎麻织物刺痒感研究

对苎麻织物的刺痒感产生的一般原因和理论 ,改善刺痒感的处理方法和刺痒感的评价方法做了详细的介绍 ,并对各种处理及评价方法进行了对比分析。提出了对麻类织物刺痒感成因和消除机理研究的必要性。

苎麻纤维增强复合材料的研究现状

综述了国内外苎麻纤维复合材料的发展历史和研究现状,包括苎麻纤维复合材料的成分和加工工艺、力学行为的表征和特点、各种影响苎麻纤维复合材料力学性能的因素,并讨论了提高苎麻纤维复合材料性能的途径和方法。