Average Fiber Length Research Articles

Production of fines from refined kraft pulp by fractionation with micro-perforated screens

Abstract The objective in this work was to obtain a fine fraction of kraft pulp, with as high concentration as possible, in a pilot-scale fractionation with micro-perforated screen baskets. The influence of screen basket surface, hole size, feed concentration, pulp type and refining segment design was investigated. The results showed that a smooth screen basket surface improved the fractionation efficiency of the unrefined pulp compared to a profiled screen basket, despite a larger hole size. A significantly higher fine fraction concentration was obtained when using refined hardwood pulp compared to when using softwood pulp, which was explained with its lower average fibre length and narrower and thus more flexible fibre fragments. The pilot trials also showed that the screening process could be operated at feed concentrations similar to those directly after a refiner, 30–40 g/l. This was demonstrated in a process layout with partial recirculation where a refiner and a micro-perforated screen basket were operated in series in pilot scale.

Extraction and Characterization of Natural Fiber from Furcraea Foetida Leaves as an Alternative Material for Textile Applications

ABSTRACT This paper reported the process of extraction and characterization of the properties of natural fiber from the leaves of the Furcraea foetida plant. The water retting method was used to extract the fiber. The fiber properties obtained were used to analyze the ability of fiber to be spun into yarn for textile application. A bundle of Furcraea foetida fibers consist of many individual fibers. The longitudinal view of the fiber cells show up as long cylindrical tubes and the cross-section of fibers were an irregular, polygonal shape. The tensile strength of the Furcraea foetida fibers was 3 g/denier. The elongation at break of the Furcraea foetida fibers was 8.61%. The fineness of the Furcraea foetida fibers was 8.3 tex. The average fiber length was 70.8 cm. The Furcraea foetida fibers were hygroscopic fibers with 8.48% moisture regain. The coefficient of friction of the Furcraea Foetida fibers was 0.053. The properties of the fiber showed that the Furcraea foetida fiber has potential to be spun into yarn. Natural fibers from the leaves of the Furcraea foetida plant could be used as an alternative material for textile application.

Design of a vane mixer with controlled extensional/shear strength ratio and its application for carbon fiber/polyamide 6 composites

AbstractIn this work, a novel melt mixing method and its corresponding mixing device are developed. The extensional/shear strength ratio of the device can be controlled by adjusting its eccentricity. The structure and working principle of the device are introduced in detail. Carbon fiber (CF)/polyamide 6 (PA6) composites are prepared via this novel mixing device. The influences of eccentricity and mixing time on the morphology, CF length, thermal, mechanical, and electrical properties of CF/PA6 composites are studied. Scanning electron microscopy results show that CFs uniformly disperse in the matrix and interfacial adhesion between CFs and PA6 is improved. It is observed that CF length and its distributions can be optimized by changing eccentricity. The maximum average fiber length is about 351 μm. Differential scanning calorimetry results exhibit that the Xc increases 6.5% when eccentricity is 2 mm. Mechanical test results show tensile strength and modulus increase first and then decrease with the increasing eccentricities or mixing time. Electrical property measurement shows an obvious increase when eccentricity is 2 mm due to good fiber dispersion and long fiber retention length. The experimental results indicate that the novel mixing method and its corresponding apparatus provide an environment‐friendly and effective way to prepare polymer‐based composites.

Otoklavsız Gazbeton Kâgir Blok Elemanlarının Üretiminde Endüstriyel Atık Liflerin Kullanımı Üzerine Teknik Bir Analiz

The presence of non-autoclaved aerated concrete masonry block elements in recent years is among the product derivatives that have become increasingly important and widespread in the development of lightweight construction materials. It can be seen that it is increasingly preferred especially in non-load bearing building units due to its low unit weights, porous structure and ease of application and technical advantages such as insulation properties. Non-autoclaved aerated concrete masonry block elements can be made with the use of many different materials, especially the use of fiber additives of different lengths and origins as matrix reinforcement materials gains a special importance in terms of recovery of industrial wastes.In this paper, preliminary findings of an ongoing experimental research and development study on the reinforcement effect in matrix structure of 3 different fiber types that can be considered in the industrial waste fiber category are technically discussed. This research study focuses on the production of non- autoclaved pre-cured, expanded masonry block elements using fiber additives. Two of these fiber types are fiber materials obtained from the recycling of denim fabric by opening denim fiber. In this study, these fibers are coded as Fiber 1 and Fiber 2. The fiber type, coded as fiber 1, has a cotton/synthetic ratio of 90/10. Its maximum fiber length is 3 mm. In the fiber type coded as fiber 2, it has a ratio of 70/30 cotton/ synthetic. In addition, the maximum fiber length of this fiber material is 2 mm. The fiber, coded as Fiber 3, is a medium-sized, 100% natural, highly pure cellulose white fiber with an average fiber length of~200µm, obtained from recycling industrial paper waste.

Evaluation of Wool Quality Parameters of Polish Sheep Breeds

ABSTRACT The aim of the study was exploration of the properties of wool derived from sheep reared in Poland. Twenty-nine breeds of sheep diverse from the type of farming, e.g. for meat, dual-purpose breeds for wool-milk, and versatile wool are bred in Poland, but only few of them have uniform wool. Because there is a lack of data determining quality and quantity of Polish wool, the wool-based textile industry in Poland uses mainly imported raw material. Wool quality has an impact on processing efficiency and determines possibility of its further use. In order to assess the wool quality from the local sheep breeds (Polish Merino, Olkuska, Żelaźnieńska, Polish Lowland Sheep), fiber parameters were evaluated: average fiber diameter, length, curvature, and comfort factor. The wool was subjected to microscopic analysis and color examination. Results of the study showed that wool from the above-mentioned sheep breeds varies greatly in terms of quality. The obtained data helps fill the information gap on Polish wool.

A Comparative Study of Pellet-Based Extrusion Deposition of Short, Long, and Continuous Carbon Fiber-Reinforced Polymer Composites for Large-Scale Additive Manufacturing

Abstract Pellet-based extrusion deposition of carbon fiber-reinforced composites at high material deposition rates has recently gained much attention due to its applications in large-scale additive manufacturing. The mechanical and physical properties of large-volume components largely depend on their reinforcing fiber length. However, very few studies have been done thus far to have a direct comparison of additively fabricated composites reinforced with different carbon fiber lengths. In this study, a new additive manufacturing (AM) approach to fabricate long fiber-reinforced polymer (LFRP) was first proposed. A pellet-based extrusion deposition method was implemented, which directly used thermoplastic pellets and continuous fiber tows as feedstock materials. Discontinuous long carbon fibers, with an average fiber length of 20.1 mm, were successfully incorporated into printed LFRP samples. The printed LFRP samples were compared with short fiber-reinforced polymer (SFRP) and continuous fiber-reinforced polymer (CFRP) counterparts through mechanical tests and microstructural analyses. The carbon fiber dispersion, distribution of carbon fiber length and orientation, and fiber wetting were studied. As expected, a steady increase in flexural strength was observed with increasing fiber length. The carbon fibers were highly oriented along the printing direction. A more uniformly distributed discontinuous fiber reinforcement was found within printed SFRP and LFRP samples. Due to decreased fiber impregnation time and lowered impregnation rate, the printed CFRP samples showed a lower degree of impregnation and worse fiber wetting conditions. The feasibility of the proposed AM methods was further demonstrated by fabricating large-volume components with complex geometries.

Papermaking as Potential Use of Fibers from Mexican Opuntia ficus-indica Waste

The papermaking potential of Opuntia ficus-indica (OFI) waste fibers was studied in this research. Alpha cellulose, lignin, hollocellulose, ethanol/benzene extractives and ash content were determined as 53.7±0.1%, 2.4±0.3%, 61.6±5.7%, 7.1±0.3% and 26.4±0.1%, respectively. The average fiber length, width, lumen and cell wall thickenss were found to be 1.1±0.3 mm, 18.8±6.1µm, 12.1±5.4 µm, 4.3±1.0 µm. Soda pulping was conducted using 20 and 28% sodium hydroxide, cooking temperatures of 160 and 175 °C, cooking times of 60 and 120 min, and liquor- to fiber ratio of 9:1. Soda pulping with 28% sodium hydroxide, 175 °C and 120 min showed a lower Kappa number of 29.60±1.7 and a total yield of 32.2±1.6 %. In general, tensile strength index (36.0±5.0 Nm/g), stretch (1.7±0.3%), breaking length (3.7±0.5 km), burst index (3.2±0.4 KPa.m2/g), tear index (7.3±0.0 mN.m2/g), folding endurance (166 times) and porosity (> 120 s) of OFI pulp were comparable with wood and non-wood pulps.

Fibre length and loading impact on the properties of glass fibre reinforced polypropylene random composites

Polypropylene composites have emerged as alternative materials for a wide range of applications requiring advanced mechanical and thermal properties including automotive and structural engineering. The choice of suitable polypropylene reinforcing agent enables higher flexibility, lightweight, mechanical strength and low production cost. This paper reports on the fabrication of short glass fibre reinforced random polypropylene by melt mixing. The mechanical and thermal properties of the random polypropylene/E-glass fibre composites exhibited a strong dependence on the fibre size varying from 1 mm to 0.3 mm and the various fibre contents, namely 10, 15, 20 and 30 wt%. Activation energy analysis suggested hindering of crystallization due to the presence of the fibres. However, a maximum yield strength of 29.4 MPa was measured for the 10 wt% fibre reinforced composites with an average fibre length of 1 mm. Furthermore, use of shorter fibres (average length of 0.3 mm) and a filler loading of 10 wt% resulted in a maximum elongation at break of 654%. Enhanced stiffness was also observed for fibre content up to 15%. These results suggest that the use of short glass fibres will allow the development of cost-effective and robust polypropylene composites adequate for a wide range of modern applications.

Data-Driven Multiobjective Predictive Optimal Control of Refining Process With Non-Gaussian Stochastic Distribution Dynamics

The fiber length and the Canadian standard freeness (CSF) are two key indices in measuring pulp quality of the refining process with non-Gaussian stochastic distribution dynamics. Among them, it is defective to use the conventional 1-D average fiber length (AFL) as a pulp quality index because the AFL is insufficient to describe the 2-D probability density function (pdf) shaping of fiber length distribution (FLD) with non-Gaussian types. In this article, a data-driven multiobjective predictive optimal control method is proposed to control the 2-D pdf shaping of FLD and the 1-D CSF, simultaneously. First, a radial basis function neural network (RBF-NN) based stochastic distribution model is developed to approximate the 2-D pdf shaping of FLD, and the parameters of RBF basis functions are updated by an iterative learning rule. Then, taking the developed pulp quality models, including the 2-D pdf model of FLD and the model of 1-D CSF as two predictors, a multiobjective predictive controller is designed by solving the nonlinear programming problems with constraints. Then, the stability of the resulted closed-loop system is also analyzed. Ultimately, the industrial experiments demonstrate the effectiveness of the proposed method.

Improvement in mechanical properties of recycled polypropylene composite by controlling the length distribution of glass fibers

AbstractA change in the length distribution of glass fiber was induced by mixing long glass fiber 30%‐ reinforced polypropylene composites with recycled composites of short glass fiber 30%‐reinforced polypropylene, and the improvement in mechanical properties was investigated. Changes in mechanical properties were confirmed as a function of the number of recycles and mixing ratio of the composites, and the average fiber length and length distribution of the glass fibers were analyzed using a three‐dimensional measuring machine. The tensile strength, flexural strength, flexural modulus, and impact strength of the blend of a once‐recycled composite of short glass fiber‐reinforced polypropylene and once‐recycled composite of long glass fiber‐reinforced polypropylene in a ratio of 40:60 were 99%, 102%, 100%, and 100% those of a virgin composite of short glass fiber‐reinforced polypropylene, respectively. In addition, the average length of the glass fiber of this blend was 0.305 mm, which was similar to that of the virgin composite of short glass fiber‐reinforced polypropylene (0.313 mm); furthermore, the distribution ratio of long fibers of length 1 mm or more was 5%. The length distribution of the glass fibers was significantly altered by the combination of the recycled composites and the long glass fiber‐reinforced composite; accordingly, the deteriorated mechanical properties of the recycled composites could be significantly recovered.

Assessment of the papermaking potential of processed Miscanthus × giganteus stalks using alkaline pre-treatment and hydrodynamic cavitation for delignification

One way of satisfying increased market demand and simultaneously achieving a reduced environmental load in the industrial paper production is the use of fibrous agricultural residues. The aims of this study were i) to investigate the effect of alkaline – hydrodynamic cavitation (HC) pre-treatments on the delignification of Miscanthus × giganteus stalks (MGS) and ii) establishing the suitability of MGS as feedstock and their exploitation in pulp and paper manufacturing. It was demonstrated that the proposed treatment is an efficient delignification method for the non-wood fiber sources, such as miscanthus. A significant outcome of this work was the observation that HC treatment preserved the fibres lengths and surface quality of raw MGS, but at the same time increased the amount of kinked and curled fibers present in cavitated miscanthus fibers. The average miscanthus fiber length was found to be relatively short at 0.45 (±0.28) mm, while the slenderness ratio, the flexibility coefficient and Runkel ratio values were calculated to be 28.13, 38.16 and 1.62, respectively. The estimated physical properties of MGS pulp hand-sheets were 24.88 (±3.09) N m g−1 as the tensile index, 0.92 (±0.06) kPa m2 g−1 as the burst index and 4.0 (±0.37) mN m2 g−1 as the tear index. Overall the current work demonstrated effective use of hydrodynamic cavitation for improving the processing in pulp and paper manufacturing.

Fiber shortening during injection molding of glass fiber-reinforced phenolic molding compounds: fiber length measurement method development and validation

ABSTRACT Thermoset molding compounds based on glass fiber-reinforced phenolic resins are an attractive material for thermo-mechanically demanding applications. Usually, the average fiber length in commercially available molding compounds is significantly shorter than the critical fiber length. In order to investigate the potential for increasing the fiber length in the molded part, molding trials using a conventional short fiber and an experimental long fiber-reinforced compound are carried out and the fiber shortening during the process is analyzed. An improvement to the fiber length measurement is described, consisting of a repeatable and accurate down-sampling and fiber dispersion method. The nondestructive measurement of the fiber length distribution by means of X-ray computed tomography is evaluated regarding its suitability for molding compounds with a high glass fiber content. By using the introduced fiber length measurement method, a fiber shortening during the injection molding process from 370µm initial weighted average fiber length to 300µm is detected for conventional phenolic molding compounds. In contrast, the experimental long fiber phenolic compound is shortened from 11,800µm to 970µm. Analytical calculations indicate that the asymptotic fiber length, until which the fluid forces during processing are sufficiently high for breaking the fibers, is between the two measurements. This leads to the conclusion that the commercially available, state-of-the-art short fiber molding compounds leave a strong potential for improving the fiber length in the molded part unused.

Effect of matrix heterogeneity on cell mechanosensing.

Cells sense mechanical signals within the extracellular matrix, the most familiar being stiffness, but matrix stiffness cannot be simply described by a single value. Randomness in matrix structure causes stiffness at the scale of a cell to vary by more than an order of magnitude. Additionally, the extracellular matrix contains ducts, blood vessels, and, in cancer or fibrosis, regions with abnormally high stiffness. These different features could alter the stiffness sensed by a cell, but it is unclear whether the change in stiffness is large enough to overcome the noise caused by heterogeneity due to the random fibrous structure. Here we used a combination of experiments and modeling to determine the extent to which matrix heterogeneity disrupts the potential for cell sensing of a locally stiff feature in the matrix. Results showed that, at the scale of a single cell, spatial heterogeneity in local stiffness was larger than the increase in stiffness due to a stiff feature. The heterogeneity was reduced only for large length scales compared to the fiber length. Experiments verified this conclusion, showing spheroids of cells, which were large compared to the average fiber length, spreading preferentially toward stiff inclusions. Hence, the propagation of mechanical cues through the matrix depends on length scale, with single cells being able to sense only the stiffness of the nearby fibers and multicellular structures, such as tumors, also sensing the stiffness of distant matrix features.

Strength Improvement of the Coloring Paper for Fruit Bag by Using Non-woody Bamboo Kraft Pulp

In this study, we evaluated the effect of bamboo bleached kraft pulp (BKP) on the strength of the coloring paper used for pear paper bags. The characteristics of bamboo BKP were measured to compare them with those of softwood BKP and hardwood BKP. Handsheets from bamboo and hardwood BKPs were prepared at various mixing ratios, and their strengths were then analyzed. After that, a mill trial was performed to produce a prototype of coloring paper with bamboo BKP, and the effect of bamboo BKP on the strength of the coloring paper was finally determined. The initial freeness and fiber shape of bamboo BKP were similar to those of hardwood BKP, although the average fiber length and curl of bamboo BKP were higher than those of hardwood. As the mixing ratio of bamboo BKP increased, the strength of the handsheets increased, indicating the enhancing effect of bamboo BKP on the strength of coloring paper. As a result of the mill trial of coloring paper in the specialty paper mill, it was found that the tensile strength increased by 27.8% and burst strength by 20.0% when bamboo chemical pulp replaced 20% of the hardwood chemical pulp. Therefore, it was concluded that bamboo chemical pulp can replace and improve the strength of hardwood chemical pulp for manufacturing coloring paper.

Corneal confocal microscopy compared with quantitative sensory testing and nerve conduction for diagnosing and stratifying the severity of diabetic peripheral neuropathy

IntroductionDiabetic neuropathy can be diagnosed and assessed using a number of techniques including corneal confocal microscopy (CCM).Research design and methodsWe have undertaken quantitative sensory testing, nerve conduction studies and CCM...

Optimization and validation of diffusion MRI-based fiber tracking with neural tracer data as a reference

Diffusion-weighted magnetic resonance imaging (dMRI) allows non-invasive investigation of whole-brain connectivity, which can reveal the brain’s global network architecture and also abnormalities involved in neurological and mental disorders. However, the reliability of connection inferences from dMRI-based fiber tracking is still debated, due to low sensitivity, dominance of false positives, and inaccurate and incomplete reconstruction of long-range connections. Furthermore, parameters of tracking algorithms are typically tuned in a heuristic way, which leaves room for manipulation of an intended result. Here we propose a general data-driven framework to optimize and validate parameters of dMRI-based fiber tracking algorithms using neural tracer data as a reference. Japan’s Brain/MINDS Project provides invaluable datasets containing both dMRI and neural tracer data from the same primates. A fundamental difference when comparing dMRI-based tractography and neural tracer data is that the former cannot specify the direction of connectivity; therefore, evaluating the fitting of dMRI-based tractography becomes challenging. The framework implements multi-objective optimization based on the non-dominated sorting genetic algorithm II. Its performance is examined in two experiments using data from ten subjects for optimization and six for testing generalization. The first uses a seed-based tracking algorithm, iFOD2, and objectives for sensitivity and specificity of region-level connectivity. The second uses a global tracking algorithm and a more refined set of objectives: distance-weighted coverage, true/false positive ratio, projection coincidence, and commissural passage. In both experiments, with optimized parameters compared to default parameters, fiber tracking performance was significantly improved in coverage and fiber length. Improvements were more prominent using global tracking with refined objectives, achieving an average fiber length from 10 to 17 mm, voxel-wise coverage of axonal tracts from 0.9 to 15%, and the correlation of target areas from 40 to 68%, while minimizing false positives and impossible cross-hemisphere connections. Optimized parameters showed good generalization capability for test brain samples in both experiments, demonstrating the flexible applicability of our framework to different tracking algorithms and objectives. These results indicate the importance of data-driven adjustment of fiber tracking algorithms and support the validity of dMRI-based tractography, if appropriate adjustments are employed.

Abnormal rich club organization in end-stage renal disease patients before dialysis initiation and undergoing maintenance hemodialysis

BackgroundEnd-stage renal disease (ESRD) patients are at a substantially higher risk for developing cognitive impairment compared with the healthy population. Dialysis is an essential way to maintain the life of ESRD patients. Based on previous research, there isn’t an uncontested result whether cognition was improved or worsened during dialysis.MethodsTo explore the impact of dialysis treatment on cognitive performance, we recruited healthy controls (HCs), predialysis ESRD patients (predialysis group), and maintenance hemodialysis ESRD patients (HD group). All ESRD patients performed six blood biochemistry tests (hemoglobin, urea, cystatin C, Na+, K+, and parathyroid hormone). Neuropsychological tests were used to measure cognitive function. By using diffusion tensor imaging and graph-theory approaches, the topological organization of the whole-brain structural network was investigated. Generalized linear models (GLMs) were performed to investigate blood biochemistry predictors of the neuropsychological tests and the results of graph analyses in the HD group and predialysis group.ResultsNeuropsychological analysis showed the HD group exhibited better cognitive function than the predialysis group, but both were worse than HCs. Whole-brain graph analyses revealed that increased global efficiency and normalized shortest path length remained in the predialysis group and HD group than the HCs. Besides, a lower normalized clustering coefficient was found in the predialysis group relative to the HCs and HD group. For the GLM analysis, only the Cystatin C level was significantly associated with the average fiber length of rich club connections in the predialysis group.ConclusionsOur study revealed that dialysis had a limited effect on cognitive improvement.

WebNet: A biomateriomic three-dimensional spider web neural net

Spiders, silks and webs are abundant in most ecosystems, suggesting that they are a significant evolutionary success. The structures they build – in particular various forms of webs – have intrigued engineers for a long time, and elucidated inspiration for new mechanical designs of de novo materials. Here we report the development of a biomateriomic neural network based constitutive model to describe the mechanical features, such as strength and toughness, of a 3D spider web depending on salient structural features, specifically: average fiber lengths, fiber orientations, web connectivity, and web density. In particular, we focus our study on the structural and mechanical properties of a Cyrtophora citricola spider web, and report a method to derive the neural net model directly from the experimental–computational mesoscale modeling, using a novel data augmentation method. Our machine learning model captures the complex biomateriomical mechanics of spider webs. More generally, approaches such as reported here can be useful to describe the intricate relationships in other hierarchical materials, and provide a basis to develop multiscale models, and bridge experimental data with computational and theoretical modeling efforts.

Effect of Pulp Properties on the Power Consumption in Low Consistency Refining

The power consumption in the low consistency (LC) refining is an important indicator for the optimal control of the process and it is composed of the net power and the no-load power. The refining efficiency and process characterization of LC refining are directly affected by power consumption. In this paper, the effect of pulp consistency and average fiber length on the power consumption and refining efficiency were studied through the LC refining trials conducted by an experimental disc refiner. It is found that the curve of power-gap clearance can be divided into constant power section, power reduction section, and power increase section. And the no-load power and the adjustable domain of loading applied by the refining plates will increase as the increase of pulp consistency, while the increase of net power is larger than that of no-load power which makes the increasing of refining efficiency. Meanwhile, the adjustable domain of loading applied by the refining plates can be slightly improved by increasing the average fiber length, but its effect on the no-load power in the LC refining process can be neglected. The study of power consumption in LC refining is of positive significance for the proper selection of pulp properties in LC refining, in-depth exploration of refining mechanism, and energy consumption reduction in refining.

Printed Graphene Layer as a Base for Cell Electrostimulation-Preliminary Results.

Nerve regeneration through cell electrostimulation will become a key finding in regenerative medicine. The procedure will provide a wide range of applications, especially in body reconstruction, artificial organs or nerve prostheses. Other than in the case of the conventional polystyrene substrates, the application of the current flow in the cell substrate stimulates the cell growth and mobility, supports the synaptogenesis, and increases the average length of neuron nerve fibres. The indirect electrical cell stimulation requires a non-toxic, highly electrically conductive substrate material enabling a precise and effective cell electrostimulation. The process can be successfully performed with the use of the graphene nanoplatelets (GNPs)—the structures of high conductivity and biocompatible with mammalian NE-4C neural stem cells used in the study. One of the complications with the production of inks using GNPs is their agglomeration, which significantly hampers the quality of the produced coatings. Therefore, the selection of the proper amount of the surfactant is paramount to achieve a high-quality substrate. The article presents the results of the research into the material manufacturing used in the cell electrostimulation. The outcomes allow for the establishment of the proper amount of the surfactant to achieve both high conductivity and quality of the coating, which could be used not only in electronics, but also—due to its biocompatibility—fruitfully applied to the cell electrostimulation.