Evaluation of the fineness of degummed bast fibers

Fiber fineness characteristics are important for yarn production and quality. In this paper, degummed bast fibers such as hemp, flax and ramie have been examined with the Optical Fiber Diameter Analyzer (OFDA100 and OFDA2000) systems for fiber fineness, in comparison with the conventional image analysis and the Wira airflow tester. The correlation between the results from these measurements was analysed. The results indicate that there is a significant linear co-relation between the fiber fineness measurement results obtained from those different systems. In addition, the mean fiber width and its coefficient of variation obtained from the OFDA100 system are smaller than those obtained from the OFDA2000 system, due to the difference in sample preparation methods. The OFDA2000 system can also measure the fiber fineness profile along the bast fiber plants, which can be useful for plant breeding.     

Biorefining of perennial grasses: Development of visible and near infrared tools for assessing fineness of extracted fibre

The biorefining of grass offers an opportunity to integrate primary production agriculture with the extraction of fibre. The study was aimed at developing protocols for processing ryegrass to determine fibre content and to generate visible and near infrared reflectance (Vis-NIR) calibrations for estimating fibre fineness with the aid of a new reference airflow method. The method for determining fineness of processed fibres has been adapted from flax fibre protocols. A Vis-NIR calibration using partial least squares (PLS) regression method was employed to generate models with a calibration set consisting of 85 samples obtained from fresh and ensiled grasses. The PLS model was successfully validated with 21 independent samples with a prediction error of 1.26 dtex. An optimised PLS model (r² = 0.86) consisting of 106 samples has been developed. The quality assurance protocols could be used for assessing fibre content and quality of silage, hay and fresh grass.     

A method of estimating the single flax fibre fineness using data from the LaserScan system

This paper establishes a new method for estimating the single flax fibre diameter using the LaserScan instrument. The method is based on the mathematical modelling of the experimental fibre and fibre bundle width distribution and enables the flax fibre sample composition to be analysed in terms of proportions of single fibre and fibre bundles. The method can also be applied for the analysis of flax fibre fineness distribution produced by the Optical Fibre Diameter Analyser (OFDA) instrument. This method can be used as a tool for classification of flax accessions according to the estimated single fibre diameter, for evaluation of the efficiency of chemical and biochemical treatments aimed at the modification of flax fibre, and for evaluation of the suitability of flax fibre for spinning and manufacture of composites. The method was applied for the characterisation of 83 accessions from the Linum core collection produced by CGN at Wageningen, The Netherlands. The mean and standard deviation of single fibre diameter and proportion of single fibre and fibre bundles in the sample was estimated. Experimental results were in good agreement with theoretically expected relationships between the estimated mean diameter of single fibre and characteristics of fibre width distribution such as the mode and the overall average.     

Porosity and nonwoven fabric vertical wicking rate

Fabric porosity is the result of fabric constructional parameters combination and used technology of nonwoven production. The effects of fabric porosity structure, as well as the content of hydrophilic viscose and hydrophobic polyester fibres in the web mixture, on the vertical wicking rate by nonwoven fabrics have been explored in this research. Fibrous webs with a different content of viscose and polyester fibres, with the web volume mass range of 0.019-0.035 g/cm³ were utilized during this study. The samples were produced using a dry-laid method of web forming and two methods of web bonding, e.g. needle punching and calendar bonding. Results show that higher volume porosity gives higher vertical wicking rate by all groups of tested samples regarding the content of used hydrophilic/hydrophobic fibres and that fluid flow is faster in samples with larger pores. The higher content of viscose fibres improve the vertical wicking rate, but better rising height can be achieved at samples made from 100 % of coarser polyester fibres. A prediction model of vertical wicking rate of viscose/ polyester nonwovens was developed on the basis of the fundamental constructional parameters of nonwoven fabrics (fibre fineness, type of raw material, and web density) and a non-deterministic modelling method, e.g. genetic algorithms, which can serve as a useful tool for fabric engineers by developing a nonwoven fabric in order to fit desired wicking rate.     

Lignin content and briquette quality of different fibre hemp plant types and energy sunflower

Fibre hemp and energy sunflower are potential energy crops for production of solid biomass as renewable energy. The current study estimated (i) the lignin content of fibre hemp and energy sunflower plants grown on different nitrogen treatments and (ii) the quality of the briquettes made from different plant types of fibre hemp (i.e. monoecious and dioecious), energy sunflower and the combination of fibre hemp and energy sunflower. The monoecious and dioecious fibre hemp cultivars (Chameleon, Finola and Santhica-27, USO-31, respectively) and the energy sunflower cultivar Wielkopolski were grown in the experimental field in 2008-2010 on Stagnic Luvisol soil. The plants were grown on N treatments of N0, mineral nitrogen (100 kg N ha⁻¹), cattle slurry (100 kg N ha⁻¹), sewage sludge (100 kg N ha⁻¹) and vetch (100 kg N ha⁻¹). Calorific values (16.6-17.4 MJ kg⁻¹) of briquettes pressed from different materials did not differ significantly and had relatively low sulphur (<0.05%) and chlorine content (0.03-0.37%). Briquettes with higher compactness were made from the sunflower and the dioecious hemp. Dioecious hemp had significantly higher lignin content. The dioecious hemp needs lower GDD values for maturating, its stems lignin content was higher than of monoecious hemp by harvest time and therefore this plant type is more suitable for briquetting in Nordic climatic conditions. Comparison of the different N treatments indicated that application of sewage sludge decreased the emergence and density of the fibre hemp plants and the lignin content per kg of DM.     

Influence of the growth stage of industrial hemp on chemical and physical properties of the fibres

Fibre damages by the decortication process have to be avoided to achieve high quality of hemp fibres (Cannabis sativa L.) for industrial use. In addition, a well-defined separation of the single fibres by the subsequent degumming process is required. The objective of the present study is to determine the growth stage at which bark and shives can be separated from unretted industrial hemp (variety ‘Kompolti’) with as little fibre damage as possible. Furthermore, the chemical composition of the bark and the molecular weight of fibre cellulose have been analysed to estimate the fibre quality that can be achieved after a degumming process. For this, the fibres have been extracted by a standardised chemical degumming process. The investigations were carried out at nine growth stages of the plants reaching from vegetative stages to senescence. Considering only the mechanical decortication of green dry stems without degumming of the bark, the results reveal that a harvest time at the beginning of seed maturity leads to easier decortication without any effect on the tensile strength of the bast. For decortication of fresh stems including a subsequent degumming process, a harvest after the flowering of the male plants results in fibre losses during decortication and to fibres of reduced fineness.     

Diffusion of oxygen through lenticels in potato tuber

Summary Diffusion into the potato tuber of oxygen for respiration takes place only through lenticels, and not through the rest of the periderm. The number of lenticels which were capable of injection with methylene blue solution was observed to be about 100 per tuber. Rates of oxygen diffusion per lenticel varied from 0.024 to 0.296 cm³ h⁻¹ atm⁻¹ with a mean of 0.1105±0.013 cm³ h⁻¹ atm⁻¹.     

Microorganism repair after UV-disinfection of secondary-level effluent for agricultural irrigation

A pilot study of microorganism repair after UV disinfection was performed for agricultural reuse of secondary-level effluent in paddy rice fields in Korea. Effluent from the bio-filter of a 16-unit apartment was used in a flow-through type UV-disinfection system. The average concentration of suspended solids (SS) and biochemical oxygen demand (BOD) were 3.4 and 5.9 mg L⁻¹, respectively. The mean total coliform level was in the range of 1.5 × 10⁴ MPN 100 mL⁻¹. Photoreactivation and dark repair were apparent at a low UV dose (6 mW s cm⁻²). In low-dose UV disinfection, microorganisms increased within 12 h by approximately 5 and 1% due to photoreactivation and dark repair, respectively. This increase was not significant at a high UV dose (16 mW s cm⁻²). The repaired microorganisms were further inactivated, rather than reactivated, by solar irradiation, and numbers decreased to non-detectible levels after 4 h of exposure to solar irradiation. Based on UV disinfection and repair studies, a UV dose of 30 mW s cm⁻² is recommended as sufficient to produce reclaimed water virtually free of pathogens and may be adequate for disinfection of secondary effluent for agricultural irrigation in paddy rice culture.     

Structure and properties of silk fibroin modified cotton

In this research, a novel cotton fiber with a silk fibroin (SF) coating was prepared by the oxidation of a cotton thread with sodium periodate and subsequent treatment in a solution of silk fibroin. The structures of both the oxidized cotton samples and the SF modified cotton samples were investigated by Fourier transform infrared (FT-IR) in combination with X-ray photoelectron spectroscopy (XPS) analysis. Other performances such as surface morphology and breaking strength were also studied. The results indicated that the weight of the oxidized cotton samples increased during SF treatment, while that of the un-oxidized cotton (pure cotton) samples reduced after SF treatment. Compared with the pure cotton samples, the oxidized cotton clearly showed a characteristic absorption band at 1730 cm⁻¹ due to the stretching vibration of the C=O double bond of the aldehyde group. After being treated with the SF solution, the oxidized cotton fiber showed a weakened characteristic absorption band at 1730 cm⁻¹ and a new absorption band at round 1540 cm⁻¹, suggesting the formation of C-N bond between aldehyde groups in the oxidized cotton and primary amines in the silk fibroin. The results were also confirmed by XPS analysis. Compared with the oxidized cotton samples, the SF treated cottons had relatively smooth surfaces, similar breaking strength, and the improved wrinkle recovery angles. The results in this research suggest that cotton based materials with protein coating can be achieved without using any other crosslinking agents by the method introduced.     

Comparison of composites made from fungal defibrated hemp with composites of traditional hemp yarn

Aligned epoxy-matrix composites were made from hemp fibres defibrated with the fungi Phlebia radiata Cel 26 and Ceriporiopsis subvermispora previously used for biopulping of wood. The fibres produced by cultivation of P. radiata Cel 26 were more cellulose rich (78%, w/w) than water-retted hemp due to more degradation of pectin and lignin. The defibrated hemp fibres had higher fibre stiffness (88–94 GPa) than the hemp yarn (60 GPa), which the fibre twisting in hemp yarn might explain. Even though mild processing was applied, the obtained fibre strength (643 MPa) was similar to the strength of traditionally produced hemp yarn (677 MPa). The fibre strength and stiffness properties are derived from composite data using the rule of mixtures model. The fibre tensile strength increased linearly with cellulose content to 850 MPa for pure cellulose. The fibre stiffness increased also versus the cellulose content and cellulose crystallinity and reached a value of 125 GPa for pure crystalline cellulose.     

The influence of thermal stabilization stage on the molecular structure of polyacrylonitrile fibers prior to the carbonization stage

Structural transformation from a linear chain structure to crosslinked chain structure, occuring during the thermal stabilization stage of carbon fiber manufacture, was followed through the use of infrared spectroscopy, differential scanning calorimetry (DSC), elemental analysis and gel-fraction measurements. The results obtained from the analysis of IR spectroscopy showed the gradual and continuous loss of intensity of the nitrile (C≡N) vibration at 2242 cm⁻¹ closely associated with the cyclization reactions whereas the intensity loss of the methylene (CH₂) groups vibration around 2920–2939 cm⁻¹ has been attributed to the loss of hydrogen atoms as part of the dehydrogenation reactions. The dehydrogenation index, evaluated using the absorbance ratio of A₁₄₅₂/A₁₃₆₈, also indicated the gradual loss of hydrogens in agreement with decreasing hydrogen content with progressing stabilization process. IR spectroscopy also showed the emergence of new absorption bands attributed to the formation of crosslinked ladder-like structure in the 1590–1600 cm⁻¹ region. The amount of newly formed crosslinked structure was characterized using DSC conversion index, IR conversion index and gel-fraction measurements. The results are compared and discussed in detail.     

Analysis of green hemp fibre reinforced composites using bag retting and white rot fungal treatments

The main objective of this project was to investigate two low cost treatment methods, namely bag retting and treatment with white rot fungi, which could be applied to hemp fibre with low environmental impact to improve its interfacial bonding with polypropylene. Wet chemical analysis, FTIR, scanning electron microscopy (SEM), X-ray diffraction (XRD), zeta potential and single fibre tensile testing were used to characterise the effect of treatment on hemp fibres. It was found that all the treatments increased the tensile strength of composites. White rot fungi Schizophyllum commune (S.com) treated fibre composites had the highest tensile strength of 45 MPa, an increase of 28% compared to composites using untreated fibre.     

Poly(vinylidene fluoride)/poly(ethylene-co-vinyl acetate) (20/80) blend. I. Miscibility and crystallization behavior

The miscibility and crystallization behavior of the blends of poly(vinylidene fluoride) (PVDF) and ethylene/vinyl acetate(20/80) copolymer (EVAc80) have been studied using a differential scanning calorimeter and a polarizing microscope equipped with a heating stage. From the melting point depression, the values of interaction energy densityB were calculated to be −1.3004 (cal/cm³) and the Flory-Huggins interaction parameterχ ₁₂ was found to be −0.0818 at 445.6 K. With increasing concentration of EVAc80, the radial growth rate of spherulite was reduced drastically. The FT-IR analysis of samples quenched from the melt to various temperatures showed increasing content ofβ-phase with increasing amount of blended EVA80 along with lower quenching temperature.     

Synthesis and electropolymerization of 9-tosyl-9<Emphasis Type="Italic">H</Emphasis>-carbazole,electrochemical impedance spectroscopic study and circuit modelling

This work reports on the newly synthesized 9-tosyl-9H-carbazole (TsCz) monomer. Capacitive properties of the electrochemically grown homopolymer, poly(TsCz) film on carbon fibre microelectrode (CFME), are characterised by cyclic voltammetry (CV), Fourier transform infrared reflectance-attenuated total reflection spectroscopy (FTIR-ATR), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Different monomer concentrations (1, 3 and 10 mM) were used for electrodeposition in 0.1 M sodium perchlorate (NaClO₄)/acetonitrile (ACN) solution. The capacitive behaviour of modified CFMEs was defined via Nyquist, Bode-magnitude and Bode-phase plots. An equivalent electrical circuit R(CR)(QR)(CR) for different concentrations of poly(TsCz)/CFME was proposed and experimental data were simulated to obtain the numerical values of the circuit components. The Nyquist plot for poly(TsCz) shows the highest specific capacitance (50.0 mF cm⁻²) at frequency of 0.01 Hz in the initial monomer concentration of 10 mM.     

OFDA细度仪及其在苎麻测试上的应用

本文主要介绍USTER公司生产的OFDA光学纤维直径分析仪的测试原理和方法,及其在苎麻纤维支数测试上的应用,列出了用OFDA仪器测定法与传统的中段称重法对苎麻纤维支数的实测结果,同时对两种测试方法的测定数据进行了稳定性分析及误差分析,用数据分析说明用OFDA仪器测定法测定苎麻纤维支数的优越性和可行性。     

Influence of agronomic factors on yield and quality of hemp (Cannabis sativa L.) fibre and implication for an innovative production system

Research and development of an innovative production system for hemp (Cannabis sativa L.) fibre for textile use requires the integration of multidisciplinary knowledge from cultivation technique to realization of end products. Research was carried out to study the effect of the agronomic factors cultivation year (2003–2004), genotype (Futura 75 and Tiborszallasi), plant population (120, 240 and 360 plants m⁻²) and harvesting time (beginning and full flowering) on fibre yield and quality in the whole hemp stem, and in the basal and apical stem portions separately. The study of separate stem portions was done to determine the effect on fibre quality of an innovative harvesting and processing system in which hemp stems are cut in two portions of approximately 1 m at harvest to enable processing on modern flax scutching lines.     

Effect of Cultivar, Year Grown, and Cropping System on the Content of Tocopherols and Tocotrienols in Grains of Hulled and Hulless Barley

In a three-year period (2000–2002) total tocols (tocopherols and tocotrienols), content of vitamin E and its isomers (α-, β+γ-, δ-tocopherols and tocotrienols) were assessed in grain of 13 barley genotypes. The highest content of tocols (60.3–67.6 mg kg⁻¹) and content of vitamin E (Vitamin E equivalent—18.0–20.1 mg kg⁻¹) were determined in the waxy varieties Wanubet, Wabet, and Washonubet. Standard varieties, i.e. of a malting type (Krona and Kompakt), had statistically significantly lower content of tocols (49.9 and 53.6 mg kg⁻¹) and vitamin E (15.7–16.1 mg kg⁻¹) compared to the waxy varieties. The hulless waxy variety Washonubet had statistically significantly higher total content of tocols (67.6 mg kg⁻¹) and α- tocotrienols isomer (42.1 mg kg⁻¹) versus all other genotypes in the set. Chemical treatment and fertilization statistically significantly increased the content of tocols (by 4.7 mg kg⁻¹), vitamin E (by 1.9 mg kg⁻¹), isomer α-tocopherol (by 0.9 mg kg⁻¹) and isomer α- tocotrienols (by 3.3 mg kg⁻¹). The average values of α-tocopherols and α-tocotrienols in the set were 6.7 mg kg⁻¹ and 29.7 mg kg⁻¹, respectively. Some of the reciprocal lines created by us from the malting and waxy varieties are suitable for food use for high contents of all tocopherols and α-tocotrienols.     

The effect of physiological age and planting date on the response of potatoes to applied nitrogen and on levels of residual nitrogen post-harvest

Summary Experiments were conducted on sandy and deep silty soils to assess the effect of physiological age of seed tubers and planting date on the response of potatoes to nitrogen fertiliser. Nitrogen optima commonly had large standard errors which made interpretation of the data difficult. On the sandy soil with cv. Record, early planting increased yield in two years but had no effect on mean N optimum (303 kg ha⁻¹, NOpt). Mean NOpt was less on the silty soil where the cv. Pentland Squire was grown, and was reduced from 273 kg ha⁻¹ to 241 kg ha⁻¹ when planting was delayed by 4 weeks. Physiological age had no effect on NOpt. On the sandy soil, residual soil mineral nitrogen (RSMN) increased by 0.05 kg ha⁻¹ per kg N fertiliser applied; on the silty soil the increase was four times as large. RSMN was larger following the late planted crop on the silty soil in one year.     

Chemical composition and content of antinutritional factors in Polish cultivars of peas

The seeds of 15 Polish pea varieties contained from 221 to 281 g/kg crude protein with a mean of 240.2±3.5 g/kg dry matter (DM). The weight of 1000 pea seeds, depending on cultivar, ranged from 209.4 to 280.4 g. No interactive effect between the seed mass and the crude protein content was detected. The highest significant negative correlation between weight of seeds and dietary fiber content wasr=−0.815^XX. The content of dietary fiber ranged from 161.5 to 209.9 g/kg with a mean of 187.9±3.8 g/kg. The mean gross energy of seeds was 18.1±0.28 MJ/kg. Amino acid composition of all the cultivars was similar, which was indicated by a similar index of essential amino acids (EAAI) of about 69.7±0.25. Trypsin inhibitor content in seeds was from 2.83 to 7.32 TIU/mg and the content of phytates ranged from 6.32 to 13.36 mg/g DM. The mean content of polyphenols and flavanols in analysed pea cultivars was 0.92 amd 0.46 mg/g, respectively. In the seeds of most cultivars little or no pyrimidine glucosides, i.e. vicine and convicine, were found. The overall mean oligosaccharide content was 64.3±1.8 g/kg, of which α-galactosides were 46.8±2.0 g/kg. The antinutritional factor content was not significantly correlated with protein content. No statistical relationship was found between crude protein and dietary fiber content. It was observed that pea cultivars with higher trypsin inhibitor activity contained significantly less flavanols (r=−0.607^X) and α-galactosides (r=−0.617^X). The varieties with higher seed content of dietary fiber contained the highest amount of α-galactosides (r=0.514^X).     

Bio-accumulation and distribution of heavy metals in fibre crops (flax,cotton and hemp)

Flax, hemp and cotton, grown in industrially polluted region, were included in the present research. The experimental plots were situated at different distances (0.5 and 15 km) from the source of pollution—the Non-Ferrous-Metal Works (MFMW) near Plovdiv. We investigated the level of pollution and the way heavy metals enter the fibre crops, by taking soil and plant samples. The contents of heavy metals in plant materials (roots, stems, leaves, seeds, flowers) were determined after the method of the dry mineralization. The quantitative measurements were carried out with inductively-coupled plasma (ICP).A clearly distinguished species peculiarity exists in the accumulation of heavy metals in the vegetative and reproductive organs of flax, hemp and cotton. Flax is the crop that most strongly absorbs and accumulates heavy metals from the soil, followed by hemp and cotton. The distribution of the heavy metals along the plant axis of the studied crops seems to be selective, therefore their contents in flax and hemp are decreasing in the following order: roots>stems>leaves>seeds, while in cotton: leaves>seeds>roots>stems. A strongly exhibited tendency towards decrease of the contents of heavy metals in the fibre crops is observed as the distance from the NFMW increases.Flax and hemp are cultures, suitable for growing in industrially polluted regions—they remove considerable quantities of heavy metals from the soil with their root system and can be used as potential crops for cleaning the soil from heavy metals.