Fiber Diameter Distribution Research Articles

Oxidative and glycolytic skeletal muscles deploy protective mechanisms to avoid atrophy under pathophysiological iron overload.

BackgroundIron excess has been proposed as an essential factor in skeletal muscle wasting. Studies have reported correlations between muscle iron accumulation and atrophy, either through ageing or by using experimental models of secondary iron overload. However, iron treatments performed in most of these studies induced an extra‐pathophysiological iron overload, more representative of intoxication or poisoning. The main objective of this study was to determine the impact of iron excess closer to pathophysiological conditions on structural and metabolic adaptations (i) in differentiated myotubes and (ii) in skeletal muscle exhibiting oxidative (i.e. the soleus) or glycolytic (i.e. the gastrocnemius) metabolic phenotypes.MethodsThe impact of iron excess was assessed in both in vitro and in vivo models. Murine differentiated myotubes were exposed to ferric ammonium citrate (FAC) (i.e. 10 and 50 μM) for the in vitro component. The in vivo model was achieved by a single iron dextran subcutaneous injection (1 g/kg) in mice. Four months after the injection, soleus and gastrocnemius muscles were harvested for analysis.Results In vitro, iron exposure caused dose‐dependent increases of iron storage protein ferritin (P < 0.01) and dose‐dependent decreases of mRNA TfR1 levels (P < 0.001), which support cellular adaptations to iron excess. Extra‐physiological iron treatment (50 μM FAC) promoted myotube atrophy (P = 0.018), whereas myotube size remained unchanged under pathophysiological treatment (10 μM FAC). FAC treatments, whatever the doses tested, did not affect the expression of proteolytic markers (i.e. NF‐κB, MurF1, and ubiquitinated proteins). In vivo, basal iron content and mRNA TfR1 levels were significantly higher in the soleus compared with the gastrocnemius (+130% and +127%; P < 0.001, respectively), supporting higher iron needs in oxidative skeletal muscle. Iron supplementation induced muscle iron accumulation in the soleus and gastrocnemius muscles (+79%, P < 0.001 and +34%, P = 0.002, respectively), but ferritin protein expression only increased in the gastrocnemius (+36%, P = 0.06). Despite iron accumulation, muscle weight, fibre diameter, and myosin heavy chain distribution remained unchanged in either skeletal muscle.ConclusionsTogether, these data support that under pathophysiological conditions, skeletal muscle can protect itself from the related deleterious effects of excess iron.

Electrospun poly(e‐caprolactone)/propolis fiber morphology: A process optimisation study

AbstractThis study focuses on combining the synthetic polymer poly(Ɛ‐caprolactone) with the natural antibacterial propolis, and uses response surface methodology based on a three‐level, four‐variable Box–Behnken design, to model the dependence of fiber diameter distribution on process parameters. The effect of the concentration of the antibacterial substance, the flow rate, the voltage, and the collector distance were analyzed. The linear coefficients of the antibacterial content and flow rate, and the quadratic coefficients of the voltage, distance and flow rate as well as the interaction effect between voltage and distance were found to be statistically significant. Parameters capable of forming small diameter fibers were targeted for higher surface area to material volume ratios. The parameters predicted to produce a minimum average fiber diameter of 0.506 μm were then validated in a confirmatory experiment giving a 0.505 μm average. The model maps the impact of electrospinning parameters on the fabrication and morphology of PCL/propolis scaffolds, which have potential woundcare applications.

Structure and rheological studies of phosphorylated cellulose nanofibrils suspensions

Cellulose nanofibrils (CNFs) are normally handled in the form of aqueous suspensions. Therefore, their rheology and intrinsic flow features in an aqueous state also fascinated the researchers. However, understanding the structure-rheology relationship remains a profound challenge to design CNFs with desirable properties. For that purpose, jute fibers were used as source material (Corchorus olitorius) to produce CNFs, and pretreatment using phosphorylation was applied to facilitate the fibrillation during ultra-sonication. This study aims to investigate the relationship between the microstructure and their rheology for CNF aqueous suspensions as influenced by the temperature and concentration of CNF. The surface chemistry, fiber diameter distribution, crystalline structure, thermal stability, and rheological properties of the obtained CNFs were characterized and compared. The grafting of phosphorous moieties on the surface of the fibers was confirmed by the FTIR, XPS analyses, elemental analyses, and zeta potential. Despite influencing crystallinity, phosphorylation enhanced the diameter of nanofibers. The results demonstrated that phosphorylation did not alter the main chemical structure of cellulose. The crystallographic form of the obtained CNFs remained cellulose I. The resulting fibers have nanometric dimensions (<100 nm) with high absolute zeta potential values (>30 mV). A substantial improvement in flame retardancy has also been noted for CNF due to the presence of phosphate groups. Both steady-state and dynamic rheological measurements were improved significantly upon increasing concentration from 0.5 to 2.5 wt%. All the CNF suspensions demonstrated typical shear-thinning behavior and gel-like viscoelastic character even at low concertation (0.5 wt%) due to the construction of a wire-like matrix structure. The frequency and temperature alteration, however, do not affect the viscoelastic gel-like properties of the CNF suspensions.

Boron‐containing nonwoven polymeric nanofiber mats as neutron shields in compact nuclear fusion reactors

Composite materials that contain thermally and chemically stable boron compounds are attractive candidates for applications that require high neutron absorption due to the large neutron absorption cross-section of boron. Electrospun polymer nanofibers have a unique volume-to-surface area, incorporating carbon and hydrogen atoms in their molecular structure that could moderate and thermalize incident neutrons. Nonwoven nanofibers could in turn reduce neutron scattering and increase neutron absorption by providing large surfaces and better atom economy in the shield materials. The expected high absorption will result from improved neutron interaction with high neutron absorbance hydrogen, carbon, and boron atoms in the nanofibers through increased specific surface area and atom economy. In this work, elemental boron-doped PVA polymeric nanofibers are produced for the first time to date for the application of neutron shielding. With the increasing demand for nuclear power generation and radiation therapies in medicine, the need for producing lightweight and flexible materials that could replace the traditional heavy metal/metal carbide-based shields is vital. Similarly, the need for flexible materials that could shield neutrons is also becoming critical for aerospace applications. The effect of boron content on the quality of fibers and neutron shielding capacity is evaluated by using an Am-Be neutron source. Characterization studies of produced nanofibers were carried out by SEM, TGA, FT-IR, and XPS analyses. Results have shown that PVA-based nanofibers doped with wt% 0.1 to 0.5 boron, having fiber diameter distribution between 60 and 330 nm range, could absorb up to 6% of neutron flux.

Mixture Aerosols Filtration on Filters with Wide Fibre Diameter Distribution - Comparison with Theoretical and Empirical Models

A methodology for calculating aerosol filtration efficiency using non-woven filters with polydispersity distribution of fibre diameters was formulated. In order to verify the results of the calculations experimentally, filters made of polypropylene non-woven fabric were used to filter solid (soot) and liquid (oil) aerosols and their mixtures with different concentrations. In order to increase the accuracy of the calculations, the division of the diameter distribution into several (1–100) ranges of values was considered. The influence of the number of these intervals for theoretical and empirical equations available in the literature was investigated. This effect was found to be significant, and replacing one diameter value representing all the fibres in the filter with twenty diameter ranges, each representing only a fraction of the total fibres, is sufficient to minimize the error due to the underrepresentation of the actual fibre distribution in the filter. Calculation of the mean particle size after the filter was performed using a set of theoretical and empirical equations. The calculations take into account the change in packing density, flow velocity and fibre diameter over time as a result of filling the filter with particles deposited on it. The obtained results were compared with the measurement results. It has been found that such changes in the monofilament performance model are insufficient to properly describe the effects inside the filter.

Histomorphometric study of the soleus muscle under conditions of modeling of spinal cord contusion injury: experimental morphological study

Objective. To conduct a morphometric analysis of the soleus muscle of rats after moderate spinal cord contusion injury.Material and Methods. Experiments were performed on female Wistar rats aged 8–12 months, weighing 270–320 g. Animals of the experimental group (n = 25) underwent laminectomy at the T9 level under general anesthesia and modeling of spinal contusion injury of moderate severity. Intact rats constituted the control group (n = 10). Euthanasia was performed on the 5th, 15th, 30th, 60th, 90th, and 180th days of the experiment. Paraffin sections were stained with hematoxylin-eosin and Masson, the diameters of muscle fibers were determined by computer morphometry, and histograms of their distribution were obtained.Results. In the soleus muscle, the signs of reversible reparative processes prevailed in response to neurotrophic damage. It was evidenced by a local increase in the diversity of myocyte diameters and the loss of polygonality of their profiles, focal destruction of muscle fibers, activation of the connective tissue component, disorganization of some intramuscular nerve conductors, and vascular fibrosis of perimysium. Nevertheless, the histostructure of an intact muscle prevailed in the course of the experiment, which was confirmed by the data of morphometric analysis. All histograms of the distribution of the muscle fiber diameters are unimodal with a mode in the range of 30–41 μm. On the 180th day, the maximum myocyte diameters in the histogram of the left limb muscle belonged to the range of 21–30 μm, which was typical for histograms in the intact group.Conclusion. The nature of the plastic reorganization of the soleus muscle when neurotrophic control is impaired indicates compensatory regeneration of muscle tissue by the type of restitution, which opens up the possibility of predicting the rehabilitation period. It is advisable to take this into account when developing medical and social programs and therapeutic measures, where the most important role is played by superficial neuromuscular and functional electrical stimulation.

Effect of magnetic lens on the electrospinning whipping instability, fiber diameter and its distribution

Electrospinning is an efficient and straightforward method for producing thin fibers from various materials. Although such thin fibers have diverse potential applications, the remaining problems with electrospinning are the whipping instability (also known as bending instability) of electrically charged liquid jets of polymer nanofibers and uneven fiber diameter distribution. In this study, we report a novel magnetic lens electrospinning system and discuss the principle of reducing the fiber diameter and width of the whipping circle in this electrospinning process. The effects of three types of electrospinning devices, needle-to-plate, needle-exciting coil-to-plate, and needle-magnetic lens-to-plate types, were studied through numerical simulation to analyze the electrospinning fiber collection state. For the 12 wt% polyacrylonitrile solution, when the applied voltage was 14–20 kV, the feed rate was 0.4–0.7 ml/h, and the current applied to the excitation coil or magnetic lens was 1 A, the experimental results demonstrated that, compared with needle-to-plate-type and needle-exciting coil-to-plate-type electrospinning, needle-magnetic lens-to-plate-type electrospinning produced smaller whipping circles with thinner and more uniform fibers.

Preparation and properties of enhanced lightweight nanofibrous membrane‐based desiccant

AbstractIn this article, the high‐efficiency hygroscopic nanofibrous membrane was prepared by the electrostatic spinning method, and its great moisture absorption performance came from the deployed polyacrylonitrile (PAN) and hydrophilic polyvinylpyrrolidone (PVP). Different strategies were used to improve the moisture absorption property of nanofibrous membrane under the action of inorganic salts. On the one hand, PAN and PVP with different mass ratios were used to optimize the structure of composite nanofibrous membrane. On the other hand, the addition of inorganic salts could improve the moisture absorption rate and capacity of the composite nanofibrous membrane. The experiment found that when the ratio of PAN and PVP was 11:4, the fiber diameter distribution was uniform, and the moisture absorption rate reached the maximum. The addition of electrolyte greatly improved the moisture absorption performance of the nanofibrous membrane, and the moisture absorption rate was as high as 121.93%. Furthermore, EDX mapping exhibited the uniform state of the electrolyte in the fiber membrane. The composite nanofibrous membrane moisture absorption materials introduced here displayed the advantages of light weight, high efficiency, and recyclability, which provided an efficient and simple method for the preparation of moisture absorption materials in the future.

Micromechanical Compatibility between Cells and Scaffolds Directs the Phenotypic Transition of Stem Cells

This study experimentally substantiates that the micromechanical compatibility between cell and substrate is essential for cells to achieve energetically favorable mechanotransduction that directs phenotypic transitions. The argument for this compatibility is based on a thermodynamic model that suggests that the response of cells to their substrate mechanical environment is a consequence of the interchange between forms of energy governing the cell-substrate interaction. Experimental validation for the model has been carried out by investigating the osteogenic differentiation of dental follicle stem cells (DFSCs) seeded on electrospun fibrous scaffolds. Electrospinning of blends containing polycaprolactone (PCL) and silk fibroin (SF) with varying composition of cellulose nanocrystals (CNCs) resulted in three-dimensional (3D) fibrous scaffolds with bimodal distribution of fiber diameter, which provides both macroscopically stiff and microscopically compliant scaffolds for cells without affecting the surface chemical functionality of scaffolds. Atomic force microscopy (AFM) with a colloidal probe and single-cell force spectroscopy were used to characterize cell stiffness and scaffold stiffness on the cellular level, as well as cell-scaffold adhesive interaction (chemical functionality). This study has successfully varied scaffold mechanical properties without affecting their surface chemistry. In vitro tests indicate that the micromechanical compatibility between cells and scaffolds has been significantly correlated with mechanosensitive gene expression markers and osteogenic differentiation markers of DFSCs. The agreement between experimental observations and the thermodynamic model affirms that the cellular response to the mechanical environment, though biological in nature, follows the laws of the energy interchange to achieve its self-regulating behavior. More importantly, this study provides systematic evidence, through extensive and rigorous experimental studies, for the first time that rationalizes that micromechanical compatibility is indeed important to the efficacy of regenerative medicine.

Fabrication of melt-spun fibers from irradiation modified biocompatible PLA/PCL blends

The effect of electron induced reactive processing (EIReP) on the properties of biodegradable polylactide/masticated polycaprolactone (PLA/PCL) blends was firstly investigated without introducing any chemical additives. Subsequently, the melt spinnability of EIReP modified PLA/PCL blends was explored by a piston spinning. Different PCL concentrations (0, 5 and 10 wt%), applied dose (0, 12.5 and 25 kGy) and take up speeds (500 and 2000 m min−1) were evaluated in order to investigate their influences on the fiber morphology, thermal and mechanical properties. SEM investigation indicated that the non-irradiated PLA/PCL fibers demonstrated less uniform diameter. However, the EIReP modification leads to a homogenous fiber diameter distribution hence uniform as-spun fibers can be produced. The crystallinity of PLA phase increased concomitantly with increased PCL contents for all fibers, whereas it slightly reduced by increasing dose. In addition, the crystallinity degree of neat PLA raised from 6.19 to 36.05% by increasing take up speed from 500 to 2000 m min−1. Interestingly, the irradiated PLA/PCL blend fibers with 5 and 10 wt% PCL demonstrated an increased fracture strain of 48.7 and 34.4%, respectively, compared with their non-irradiated fibers. It can be due to the enhanced chain entanglements and interfacial bonding between two phases. However, the irradiated fibers demonstrated similar initial modulus and reduced tenacity compared with the non-irradiated fibers.

Filtering efficiency model that includes the statistical randomness of non-woven fiber layers in facemasks.

Facemasks have become important tools to fight virus spread during the recent COVID-19 pandemic, but their effectiveness is still under debate. We present a computational model to predict the filtering efficiency of an N95-facemask, consisting of three non-woven fiber layers with different particle capturing mechanisms. Parameters such as fiber layer thickness, diameter distribution, and packing density are used to construct two-dimensional cross-sectional geometries. An essential and novel element is that the polydisperse fibers are positioned randomly within a simulation domain, and that the simulation is repeated with different random configurations. This strategy is thought to give a more realistic view of practical facemasks compared to existing analytical models that mostly assume homogeneous fiber beds of monodisperse fibers. The incompressible Navier-Stokes and continuity equations are used to solve the velocity field for various droplet-laden air inflow velocities. Droplet diameters are ranging from 10nm to 1.0µm, which covers the size range from the SARS-CoV-2 virus to the large virus-laden airborne droplets. Air inflow velocities varying between 0.1m·s-1 to 10m·s-1 are considered, which are typically encountered during expiratory events like breathing, talking, and coughing. The presented model elucidates the different capturing efficiencies (i.e., mechanical and electrostatic filtering) of droplets as a function of their diameter and air inflow velocity. Simulation results are compared to analytical models and particularly compare well with experimental results from literature. Our numerical approach will be helpful in finding new directions for anti-viral facemask optimization.

TWO-STEP CROSSLINKING OF PVP/GEL NANOFIBERS

In this study, it was achieved that crosslinking of PVP/GEL nanofibers with two-steps. Crosslinking is a process highly important for water-soluble polymers in terms of application areas and mechanical properties. Firstly, crosslinking of PVP polymers experimental studies were carried out via heat treatment at different temperatures and times. Then, GEL polymers were crosslinked with GTA vapour at different times. Morphological analysis was carried out via SEM images and chemical characteristics were determined via FT-IR analysis. Moreover, after the crosslinking process, SD and WL values were calculated. All results showed that before crosslinking of SEM images, nanofibers were smooth, fine and without beads. The average fiber diameter is 196 nm and the fiber diameter distribution is quite uniform. After crosslinking of SEM images, it is expected that all nanowebs will turn from fibrous surfaces to membranous. Generally, SD and WL values decrease with crosslinking time increase. According to all of the SEM images, SD and WL values, optimum conditions were determined for PVP as 4 hours at 180oC and for GEL as 24 hours. Lastly, the presence of PVP and GEL polymers in the nanofiber structure was verified chemically with FT-IR analysis.

Fiber statistics of nonwoven materials by SEM images - influence of number of images

Abstract Electrospun nonwovens are widely applied in biomedicine and various other fields. For control of the manufacturing process and quality assurance Scanning electron microscopy (SEM) imaging is one standard practice. In this study, statistical datasets of 60 SEM images of three nonwoven samples were evaluated using Gaussian fit to obtain numerical results of their fiber diameter distributions. The question of how much effort is required for acceptable imaging and processing is being discussed. As determined here, for reliable statistics, a minimum surface area of the nonwoven has to be evaluated. The fiber diameter should be in a range of approximately 2 - 3% of the edge length of the square equivalent of the evaluated image area, using sufficiently magnified SEM images, in which the fiber diameter is imaged over at least 30 pixels.

Supercritical Carbon Dioxide Isolation of Cellulose Nanofibre and Enhancement Properties in Biopolymer Composites.

The physical properties, such as the fibre dimension and crystallinity, of cellulose nanofibre (CNF) are significant to its functional reinforcement ability in composites. This study used supercritical carbon dioxide as a fibre bundle defibrillation pretreatment for the isolation of CNF from bamboo, in order to enhance its physical properties. The isolated CNF was characterised through zeta potential, TEM, XRD, and FT-IR analysis. Commercial CNF was used as a reference to evaluate the effectiveness of the method. The physical, mechanical, thermal, and wettability properties of the bamboo and commercial CNF-reinforced PLA/chitin were also analysed. The TEM and FT-IR results showed the successful isolation of CNF from bamboo using this method, with good colloidal stability shown by the zeta potential results. The properties of the isolated bamboo CNF were similar to the commercial type. However, the fibre diameter distribution and the crystallinity index significantly differed between the bamboo and the commercial CNF. The bamboo CNF had a smaller fibre size and a higher crystallinity index than the commercial CNF. The results from the CNF-reinforced biocomposite showed that the physical, mechanical, thermal, and wettability properties were significantly different due to the variations in their fibre sizes and crystallinity indices. The properties of bamboo CNF biocomposites were significantly better than those of commercial CNF biocomposites. This indicates that the physical properties (fibre size and crystallinity) of an isolated CNF significantly affect its reinforcement ability in biocomposites. The physical properties of isolated CNFs are partly dependent on their source and production method, among other factors. These composites can be used for various industrial applications, including packaging.

Influence of the Protein Content on Fiber Morphology and Heat Treatment of Electrospun Potato Protein–Maltodextrin Fibers

The production of ultrafine fibers of proteins and polysaccharides by needleless electrospinning can be performed prior to a thermal treatment to form glycoconjugates via the first stage of the Maillard reaction. The aim was to produce potato protein–maltodextrin conjugates with a varying protein content of 0.05, 0.1, 0.15, and 0.2 g/mL by needleless electrospinning and subsequent thermal treatment (0, 6, 12, 24, and 48 h at 65 °C and 75% relative humidity). The concentrations of the maltodextrins, with a dextrose equivalent of 2 and 21, were kept constant at 0.8 and 0.1 g/mL. The highest fiber production rate was achieved with a protein content of 0.1 g/mL (5.8 ± 0.4 g/h). With increasing protein content, the production rate decreased to 2.8 ± 0.5 g/h. The fibers obtained from the spinning solution containing 0.2 g/mL protein showed the largest average diameter (4.0 ± 1.5 µm) and the broadest fiber diameter distribution. The protein content of the fibers was close to that of the corresponding spinning solution. The browning index after 48 h of heating increased for all samples (9.7–14.7) compared to the unheated samples (1.1–3.3). The results indicate that the protein content has an impact on the yield, the fiber diameter, and the morphology of the fibers.

A rotary spinneret for high output of electrospun fibers with bimodal distribution

Needleless electrospinning technology is an effective method for preparing large-scale nanofibers. In the present work, we developed a multi-hole curved surface rotary spinneret to fabricate sub-micro fibrous membrane with bimodal distribution structure. First, a finite element method was adopted to investigate electric potential and electric field strength of the spinneret; the formation of coarser and finer jets has been explained from the perspective of electric field. Then, the effects of solution concentration, applied voltage and spinneret rotation speed on the bimodal distribution fibers yield were optimized via quadratic general rotary unitized design (QGRUD). Lastly, the fiber diameter distribution and the mechanical properties of sub-micro fibrous membranes were characterized. The results suggested that the bimodal distribution sub-micro fibrous membranes exhibited excellent breaking strength and tensile modulus. This novel multi-hole curved surface rotary spinneret is promising for the high-output fabrication of sub-micro fibers with bimodal distribution.

Deep Learning Based Uncertainty Analysis in Computational Micromechanics of Composite Materials

Design of new materials is quite a difficult task owing to various time and length scales and affiliated uncertainties. The major challenge is to include all these in a conventional model. Hyperparameter models in machine learning can be used to overcome these issues. In this paper, an artificial neural network (ANN) model is developed to estimate the effective elastic parameters of unidirectional fiber reinforced composites using representative volume elements (RVE) considering uncertainty in the fiber diameter. The diameter probability distribution is constructed from the acquired gray images by employing image processing operations. The generalized Polynomial Chaos (gPC) expansion is then used to represent the distribution as a random input parameter for finite element analysis, from where the effective parameters are realized. Similarly, the outputs of the FE model, i.e., elastic parameters, are approximated by gPC expansions having unknown deterministic coefficients and random orthogonal Hermite polynomials. A set of collocation points are generated from roots of the random polynomials; from there, the unknown coefficients are estimated. The realization samples are utilized to train an ANN algorithm based on supervised deep learning. The developed ANN model is later tested and validated for a new sample set of data. It is shown that the ANN model with few hidden layers and neurons has a high accuracy for estimation of the elastic parameters directly from the information on the distribution of fiber diameters.

High-resolution microscopy assisted mechanical modeling of ultrafine electrospun network

This paper demonstrates a novel hi-resolution microscopy-assisted computational approach to mechanical modeling of ultrafine electrospun networks (ESN). Morphological data extracted from X-ray microtomography (μCT) of ESN made of poly(lactic-co-glycolic acid) (PLGA), supplemented by data acquired from the nanoscale flexural test of a single fiber, was used to create a volumetric finite element (FE) model of the investigated ESN. The results of the carried-out FE simulation have been successfully validated against the results of the quasi-static tensile test. The accuracy and the reliability of the μCT-based ESN geometry have been proved by the comparison with the scanning electron microscopy (SEM) data and by the numerical analysis of fluid flow across the rendered ESN structure. The designed methodology enables the analysis of potential factors affecting the mechanical properties of electrospun structures made of aliphatic polyesters, like the depth of fiber fusion, the ESN geometric inaccuracies, and the fiber diameter distribution. Moreover, in the study, the novel experimental setup enabling for single fiber AFM flexural test was proposed, assuming deposition of fibers directly on polystyrene (PS) substrate containing crater-like wells. Additionally, the presented study contains the numerical analysis of the effect of the substrate stiffness on the results of the three-point bending test of a single fiber.

ДОСЛІДЖЕННЯ ВПЛИВУ ПРОЦЕСУ ЧЕСАННЯ НА ГЕОМЕТРИЧНІ ХАРАКТЕРИСТИКИ КОНОПЛЯНОГО ВОЛОКНА

The article analyzes the possibility of processing imported hemp raw materials to obtain household textiles using domestic technologies for processing best fibers. The choice of the carding process is justified as a mechanical effect on the geometric characteristics of hemp. A preliminary visual analysis of samples of hemp fibers, which is imported by a domestic enterprise in order to obtain yarn using a carded spinning system, has been carried out. As a result of the analysis of morphometric characteristics, it was found that the resulting fiber is hemp cottonin. The length and thickness of cottonin vary considerably. Such dimensional characteristics do not allow using it for the manufacture of household yarn. To further break down the complex hemp fibers and reduce their length, a carding process is applied. The study of the effect of the carding process was carried out while implementing five carding cycles on a laboratory fiber mixer, which is an imitation of the carding process on carding equipment in a production environment. After each carding cycle, a card canvas is formed, in which the fibers are evenly mixed and oriented in the longitudinal direction. Sizing of hemp fibers occurs after each carding cycle. According to the dimensional characteristics, staple and modal diagrams of the length distribution and diagrams of the diameter distribution of hemp fibers were constructed. It was found that as a result of the carding process, the average length and thickness of hemp fibers decreased significantly while maintaining the normalized breaking load. But at the same time, the proportion of long fibers remains and a rather high linear density of the fibers remains, which does not allow them to be processed into yarn using a carded spinning system. It is recommended that you continue with the mechanical processing process or use carded hemp fiber to make yarn using the machine’s wool spinning system.

Fabrication of a Simultaneous Highly Transparent and Highly Hydrophobic Fibrous Films

This paper discusses the fabrication and characterization of electrospun nanofiber scaffolds made of polystyrene (PS). The scaffolds were characterized in terms of their basis material molecular weight, fiber diameter distribution, contact angles, contact angle hysteresis, and transmittance. We propose an aligned electrospun fiber scaffold using an alignment tool (alignment jig) for the fabrication of highly hydrophobic (θW &gt; 125°) and highly transparent (T &gt; 80.0%) films. We fabricated the alignment jig to align the electrospun fibers parallel to each other. The correlation between the water contact angles and surface roughness of the aligned electrospun fibers was investigated. We found that the water contact angle increased as the surface roughness was increased. Therefore, the hydrophobic properties of the aligned electrospun fibers were enhanced by increasing the surface roughness. With the change in the electrospinning mode to produce aligned fibers rather than randomly distributed fibers, the transmittance of the aligned electrospun fibers increased. The increase in the porous area, leading to better light transmittance in comparison to randomly distributed light scattering through the aligned electrospun fibers increased with the fibers. Through the above investigation of electrospinning parameters, we obtained the simultaneous transparent (&gt;80%) and hydrophobic (θW &gt; 140°) electrospun fiber scaffold. The aligned electrospun fibers of PS had a maximum transmittance of 91.8% at the electrospinning time of 10 s. The water contact angle (WCA) of the aligned electrospun fibers increased from 77° to 141° as the deposition time increased from 10 s to 40 s. The aligned fibers deposited at 40 s showed highly hydrophobic characteristics (θW &gt; 140°).