Effects of nanoclay and short nylon fiber on morphology and mechanical properties of nanocomposites based on NR/SBR

Natural rubber and styrene butadiene rubber (NR/SBR) reinforced with both short nylon fibers and nanoclay (Cloisite 15A) nanocomposites were prepared in an internal and a two roll-mill mixer by a three-step mixing process. The effects of fiber loading and different loading of nanoclay (1, 3 and 5 wt. %) were studied on the microstructure and mechanical properties of the nanocomposites. The adhesion between the fiber and the matrix was improved by the addition of a dry bonding system consisting of resorcinol, hexamethylene tetramine and hydrated silica (HRH). This silicate clay layers was used in place of hydrated silica in a HRH bonding system for SBR/NR-short nylon fiber composite. Nanoclay was also used as a reinforcing filler in the matrix-short fiber hybrid composite. The cure and scorch times of the composites decreased while cure rate increased when the short fiber and nanoclay were added. The mechanical properties of the composites showed improvement in both longitudinal and transverse directions with increasing short fiber and nanoclay content. The structure of the nanocomposites was characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM). X-ray diffraction results of nanocomposites indicated that the interlayer distance of silicate layers increased. The mechanical properties of nanocomposites (tensile, hardness and tear strength) are examined and the outcome of these results is discussed in this paper.     

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.     

Preparation,composition, structure and properties of the <Emphasis Type="Italic">Kosteletzkya virginica</Emphasis> bast fiber

In this paper, the bast of the Kosteletzkya virginica are degummed and separated into fine fibers, the chemical composition, morphology, microstructure and mechanical properties of the Kosteletzkya virginica bast fibers are characterized by means of SEM, ART-FTIR, DSC-TGA, XRD and Instron tensile tester. The results show that the surface of the Kosteletzkya virginica bast fibers is smooth, and there are many visible grooves along the vertical section. Typical cellulose I in the Kosteletzkya virginica bast fibers is confirmed by FTIR and XRD analysis. The crystallinity of the Kosteletzkya virginica bast fibers is higher than that of the cotton fibers and lower than that of the castor-oil plant bast fibers. The beginning and maximum decomposition temperature of the Kosteletzkya virginica bast fibers are 252 and 347 °C respectively, which indicate that the Kosteletzkya virginica bast fibers have an appropriate thermal stability. The Kosteletzkya virginica bast fibers have a better mechanical properties and excellent hygroscopicity. All the results show that the Kosteletzkya virginica bast fiber is one of an ideal candidate for the new textile material.     

Pulp and paper from kenaf bast fibers

Samples of kenaf (Hibiscus cannabinus) grown in Malaysia were examined to determine the kraft pulp and papermaking properties of their bast (or bark) fibers. Using kraft pulping process showed that bast fibers were relatively easy to cook resulting good pulp yields in the range of 45–51%. The bast pulp produced sheets with great density, tear index and dry zero-span breaking length. Kenaf bast fiber is considered promising for production of high-grade printing, writing and specialty papers.     

Internal structure and pigment granules in colored alpaca fibers

Alpaca fibers have some distinct properties such as softness and warmth, which have not been fully understood in combination with the fiber internal structures. In the present investigation, the internal structures of alpaca fibers have been closely examined under the scanning electron microscope (SEM), especially in the longitudinal direction. The results showed that numerous pigment granules reside loosely inside pockets in brown and dark-brown alpaca fibers. These pigment granules were mainly distributed inside the cortical cells, the medullation regions as well as underneath the cuticles. Their size in the brown alpaca fibers was smaller and more uniformly round than in the dark-brown fibers. These granules in colored alpaca fibers loosen the bundle of cortical cells, providing many crannies in the fibers which may contribute to the superior flexibility, warmth and softness of the fibers. Moreover, there are no heavy metal elements found in the granules. The mordant hydrogen peroxide bleaching employed could eliminate the pigment granules and create many nano-volumes for further dyeing of fibers into more attractive colors.     

加拿大麻类研究概况

由于气候、历史和主要作物的竞争等原因,加拿大目前种植的麻类作物仅限于亚麻和大麻,作者介绍了加拿大麻类作物育种、种植、利用、科研方面的概况,并指出随着消费者对环保的日益重视和麻产品日益增长的需求,加拿大的麻类研究迎来了一个转折时期,加拿大麻类产业将会得到更大的发展.     

做大云南麻类产业打造云南绿色纺织

麻类纤维的绿色环保生态功能日益受到重视，麻类产品的市场需求不断扩大。为麻类产业的发展带来广阔前景。本文就发展云南麻类产业、打造云南绿色纺织的必要性、必然性和可行性进行论述，分析了在云南发展麻类产业的战略意义。     

Self-layering behavior of PET fiber deposition in melt-electrospinning process

Melt-electrospinning is an efficient and environmental-friendly technique for producing nano/micro fibers. In this work, the self-layering behavior of poly(ethylene terephthalate)(PET) fiber deposition during melt-electrospinning was investigated based on the electric field simulation analysis by ANSYS and high voltage insulation theory of capacitor for melt-electrospinning configuration. The simulation results demonstrated that during melt-electrospinning process, the electric field strength on the center and lateral surface of the collector changed alternately when some electrically charged jet deposited, making jet depositing location moved around between center and lateral surface, resulted in the formation of the binding fibers separating the inner and outer layers in the deposited PET fiber web. The PET fiber web electrospun in 90 minutes could be laminated freely into thirteen layers. The geometric dimensions of these layers were measured and their morphologies were observed by scanning electron microscopy (SEM). These laminated layers were concentric with almost linearly increasing radius from the inner to the outer. Inner layers featured themselves with appearance of thick center and thin edge, while for outer layers, they presented the appearance of thin center and thick edge. The fibers in the web were quite uniformly and had diameters of about 2 μm.     

Photoluminescence electrospun membranes of poly(aryl ether)s with hydrophobicity

Photoluminescence electrospun fibers were prepared from poly(aryl ether)s solutions. The porosity and wrinkle fibers could be observed by scanning electron microscopy (SEM). The effect of solution properties on fiber surface morphologies was studied. Meanwhile, the rough fiber surfaces could make the electrospun membranes possess water repellency. The contact angles of electrospun membranes for water were around 140°. The emission spectra of these membranes indicated that the fibers exhibited multi-color including sapphire blue, olive green and rose red. It could provide a proposal for improving flexible optoelectronic devices based on electrospun membranes of conjugated polymers.     

菠萝叶纤维抗菌机理的初步研究

采用相关标准,对菠萝叶纤维的抗菌性进行测试,从菠萝叶纤维形态结构、化学组成上研究菠萝叶纤维的抗菌作用和机制.结果表明,菠萝叶纤维表面有纵向裂缝和孔洞,比表面积大,易于吸附氧气.破坏了厌氧菌的生存环境;菠萝叶纤维中的酚类物质可能存在于木质素中,可阻碍细菌等微生物代谢作用和生理活动,破坏菌体的结构,最终导致菌体的生长繁殖被抑制.     

对我国麻类生产质量安全的探讨

我国是世界上庥类生产、贸易大国。目前我国庥类生产加工中存在的主要问题：质量监控检测体系不健全，原料市场较乱，良种区域化程度低，初加工技术落后，庥纺织加工水平低。所以加强麻类质量监督检测体系建设，提高类庥检测手段，规范市场行为，加强优质育种，实行良种区域化，采用先进的加工技术，加强横向联合等是提高我国麻类生产质量水平和市场竞争力的主要对策。     

麻类纤维细度数据分析测试软件的开发

本文根据优化出的麻类纤维细度与直径的相关回归模型，设计制作了通用型麻类纤维细度及细度分布的数据分析测试软件(Uitra—0FDA)，将该软件装入0FDAl00纤维直径分析仪，使0FDAl00纤维直径分析仪用于麻类纤维细度及细度分布的自动测定。U1tra—0FDA通用软件亦可应用于其它类似纤维直径分析仪。     

强化自主创新能力，促进麻业科技发展

本文分析了麻业发展中的原料生产与初加工方面存在着的优异种质缺乏、收获技术和原料脱胶技术落后等三大关键问题，提出我国麻业必须提高科技自主创新能力，加强条件设施建设，重视人才团队的培育，针对麻业发展中原料生产和脱胶技术问题进行联合攻关。以满足市场需求为科技创新目标，推动麻业向高效、环保方向发展。     

Study on polyacrylonitrile fibers modified by blending with polyethylene glycol

A series of water absorbent porous modified polyacrylonitrile (PAN) fibers were prepared using the blends of PAN and various molecular weight of polyethylene glycol (PEG) by wet-spinning process and water bath post-treatment. The chemical structure and morphologies of the modified PAN fibers were studied. The water transportation, water retention, moisture absorption and mechanical properties of the fibers were discussed. Results show that there is no residual PEG in modified PAN fibers after drawing process in hot water bath and post-treatment. With the increase in PEG molecular weight, the fiber surface grooves become deeper, the inner pore size increases, while the mechanical properties decrease. The water absorbing and transferring capabilities of the modified PAN fibers can be improved in varying degrees due to the different pore structures left by series molecular weight of PEG removing.     

Effect of boric acid on oxidative stabilization of polyacrylonitrile fibers

The coating modification of polyacrylonitrile (PAN) fibers with boric acid to enhance the controllability of thermally oxidative stabilization process. The stabilization process, cross-section morphologies of oxidized and carbonized products were investigated by means of optical microscopy, SEM, XPS and in-situ thermal shrinkage indicator. The results indicated that the coating with boric acid on fiber surface was effective to avoid skin-core heterogeneity on the cross section and, in the stabilization process, that boric acid as a crosslinking agent to tie together the adjacent oxidative molecular chains was confirmed. It was suggested that the crosslinked structures should play an essential role in controlling the formation of uniform oxidized structures, which is favorable for tensile properties of carbon fibers.     

Green composites. II. Environment-friendly, biodegradable composites using ramie fibers and soy protein concentrate (SPC) resin

Fully biodegradable and environment-friendly green composite specimens were made using ramie fibers and soy protein concentrate (SPC) resin. SPC was used as continuous phase resin in green composites. The SPC resin was plasticized with glycerin. Precuring and curing processes for the resin were optimized to obtain required mechanical properties. Unidirectional green composites were prepared by combining 65 % (on weight basis) ramie fibers and SPC resin. The tensile strength and Young’s modulus of these composites were significantly higher compared to those of pure SPC resin. Tensile and flexural properties of the composite in the longitudinal direction were moderate and found to be significantly higher than those of three common wood varieties. In the transverse direction, however, their properties were comparable with those of wood specimens. Scanning electron microscope (SEM) micrographs of the tensile fracture surfaces of the green composite indicated good interfacial bonding between ramie fibers and SPC resin. Theoretical values for tensile strength and Young’s modulus, calculated using simple rule of mixture were higher than the experimentally obtained values. The main reasons for this discrepancy are loss of fiber alignment, voids and fiber compression due to resin shrinking during curing.     

Optimization for enzyme-retting of flax with pectate lyase

Flax (Linum usitatissimum L.) is an important commercial crop that supplies both linseed and bast fibers for multiple applications. Retting, which is a microbial process, separates industrially useful bast fibers from non-fiber stem tissues. While several methods (i.e., water- and dew-retting) are used to ret flax, more recently enzymes have been evaluated to replace methods used currently. Alkaline pectate lyase (PL) from the commercial product BioPrep 3000 and ethylenediaminetetraacetic acid (EDTA) from Mayoquest 200 as a calcium chelator were used in various formulations to ret flax stems. Retted stems were then mechanically cleaned through the USDA Flax Fiber Pilot Plant and passed through the Shirley Analyzer. The PL and chelator effectively retted flax from both fiber flax and linseed stems, and the use of enzyme plus chelator retted flax stems better than either component alone. Fiber yield and strength were greater than retting with a mixed-enzyme product that contained cellulases. Retting with PL and chelator was optimized based on fine-fiber yield, remaining shive content, and fiber properties. PL at levels of about 2% of the commercial product for 1 h at 55 °C followed by treatment with 18 mM EDTA for 23–24 h at 55 °C provided the best fibers based on these criteria. Yield and fiber properties determined by these tests were not improved with PL levels of 5% of the commercial product.     

麻地膜、无纺布在设施园艺生产上的应用效果初步研究

通过对麻地膜、无纺布在大棚反季节番茄覆盖栽培的增温除湿效果观察,番茄上市期、产量、产值、生产成本及效益的记载核算,麻地膜、无纺布生产有机无土草坪的成坪效果及应用前景考查和分析,认为麻地膜、无纺布可作为农用塑料薄膜和化纤园艺基布的替代材料,用于设施园艺生产。可减轻“白色污染”对农业生产环境的危害,促进园艺产业的健康、可持续发展。同时对麻地膜、无纺布市场认可、适销对路的产品研发和推广应用提出了建议。     

Electrospinning of polycaprolatone nanofibers with DMF additive: The effect of solution proprieties on jet perturbation and fiber morphologies

Electrospinning is a straightforward method to produce sub-micrometer or nanoscale fiber. Polycaprolactone (PCL), an important polymer in biomedical applications, has been electrospun in several solvent systems. N,Ndimethylformamide (DMF) is often used as an additive in the solvent system to prepare PCL nanofibers. The adding of the DMF changes the physical properties of the solution. To trace and understand the influence of these changes on the jet formation as well as the resultant fibers morphologies, a model of jet perturbation based on the Plateau-Rayleigh Instability theory was established to explicate the formation of the particles/fibers and some experiments for testing the solution properties and fibers morphologies were carried out. With the adding of DMF in dichloromethane (DCM)/DMF mixed solvents, the solution surface tensions increase while solution viscosities decrease, which triggers the change of electrospinning to electrospraying in general. However, according to the obtained results, the addition of the DMF makes it easier to induce the transformation of particles electrospraying to fibers electrospinning with smaller diameter. This is attributed to the higher dielectric constant, lower vapor pressure, and higher electric conductivity of DMF. The theoretical model and experimental results strengthen the relations of solution properties, jet moving behaviors, and the resultant fiber morphologies.     

中国农业科学院麻类研究所科学研究回顾与展望

本文较全面地回顾了中国农业科学院麻类研究所科研成就:苎麻、亚麻、黄/红麻新品种的选育与推广;麻类及同类纤维种质资源研究;麻类种植技术研究;麻类加工技术与加工机具的研究与推广;麻类生物脱胶与产品加工研究,特别是纤维质生产乙醇及环保型麻地膜的研究。本文还分析了未来该所麻业发展的走向:从麻类作物拓展到纤维植物;加工手段从农业微生物拓展到酶制剂;产品从传统的纺织原料拓展到生物能源与生物材料。