Properties Of Single Fibers Research Articles

SEM Characterization and Tensile Properties of Alkali Treated Single Coir Fiber with Drying Procedure Variation

This study has aimed to analyze the effect of alkali treatment and drying method on the surface morphology and tensile properties of single coir fibers. The treatments of the coir fibers have been configured on the concentration of alkali solution, the soaking period, and the drying method. Furthermore, they have been soaked in 2 wt% and 6 wt% sodium hydroxide solution at room temperature for 1- and 2-hours soaking periods. The drying procedures adopted have been air, oven, and sun-drying. Observations with a scanning electron microscope (SEM) show that the coir surface is coarser, especially on fibers treated with 6 wt% sodium hydroxide solution. The properties such as tensile strength and strain, as well as tensile modulus of the different samples have been measured. The results have showed that the treated coir fiber with the 2 wt% concentration alkali solution has lower tensile strength than the untreated one. The treated coir with 6 wt% sodium hydroxides has the most considerable tensile strength. The effect of the soaking period on the tensile properties has been influenced by the drying method. Therefore, the appropriate combination of the soaking period and the drying method increase single coir fibers tensile properties. Slow drying (air-drying) has generated better tensile properties than the fast method (oven and sun-drying).

Effects of moisture and cellulose fibril angle on the tensile properties of native single Norway spruce wood fibres

Isolated single wood fibres with cellulose fibril angles from 10 to 43° were tested in microtensile tests under controlled temperature and relative humidity of 5, 50, 75, 90% and in the wet state. This systematic study provides experimental stiffness and strength data, calculated on cell wall cross sections. It has been shown that stiffness reduction with increasing moisture content is more pronounced in fibres with large cellulose fibril angles. Interestingly, stiffness reduction in fibres with low cellulose fibril angles has been observed for the fully hydrated state only. The experimental dataset was fed into a model to determine moisture dependent stiffness of the hemicellulose-lignin-matrix and the stresses acting on the fibrils and the matrix.

Dynamic Mechanical Properties of Several High-Performance Single Fibers.

High-performance fiber-reinforced composites (FRCs) are widely used in bulletproof structures, in which the mechanical properties of the single fibers play a crucial role in ballistic resistance. In this paper, the quasi-static and dynamic mechanical properties of three commonly used fibers, single aramid III, polyimide (PI), and poly-p-phenylenebenzobisoxazole (PBO) fibers are measured by a small-scale tensile testing machine and mini-split Hopkinson tension bar (mini-SHTB), respectively. The results show that the PBO fiber is superior to the other two fibers in terms of strength and elongation. Both the PBO and aramid III fibers exhibit an obvious strain-rate strengthening effect, while the tensile strength of the PI fiber increases initially, then decreases with the increase in strain rate. In addition, the PBO and aramid III fibers show ductile-to-brittle transition with increasing strain rate, and the PI fiber possesses plasticity in the employed strain rate range. Under a high strain rate, a noticeable radial splitting and fibrillation is observed for the PBO fiber, which can explain the strain-rate strengthening effect. Moreover, the large dispersion of the strength at the same strain rate is observed for all the single fibers, and it increases with increasing strain rate, which can be ascribed to the defects in the fibers. Considering the effect of strain rate, only the PBO fiber follows the Weibull distribution, suggesting that the hypothesis of Weibull distribution for single fibers needs to be revisited.

Single carbon and glass fibre properties characterised using large data sets obtained through automated single fibre tensile testing

Large data sets of fibre mechanical properties were acquired using automated single fibre tensile testing equipment to improve the reliability of the measurements on T700S, 34-700, T300, HS40 and HYBON 2026 fibres. Although with the same nominal strength and stiffness, the T700S and 34-700 showed different Weibull modulus. A high number (over ~ 200) of the tests is necessary for accurate determination of the fibre strength Weibull parameters; samplings of ~ 50 tests can lead to a Weibull modulus deviation of ±1. Carbon fibre stiffening rate was shown to depend on the fibre type, contrary to previous reported observations. The stiffness of E-glass fibre, however, decreased with the applied strain. The non-linearity of the fibre stress-strain diagrams implies that the necessary compliance calibration should be done iteratively.

Importance of axial stretch on the determination of Young’s modulus of electrospun poly(ε-caprolactone) nanofibres by atomic force microscopy

With increasing interest in the use of polymeric nanofibres for biomedical applications such as composite materials and tissue scaffolding, accurate determination of their mechanical properties is essential. Fibre orientation and the stiffness of individual fibres determine the overall elastic modulus of nanofibrous materials. However, accurate measurements of the elastic properties of single fibres are challenging at the nanoscale, and distinguishing between results arising from competing models can be difficult. We report here on investigations of the Young’s modulus of single poly(ε-caprolactone) (PCL) electrospun nanofibres by measuring the deflection of fibres due to a loading force applied by an atomic force microscope (AFM). Although such testing is often performed with the tacit assumption that bending resistance alone is responsible for the fibre response, we found that consistent results could only be obtained if the overall fibre stretch is taken into account. The Young’s modulus we measured for electrospun PCL fibres with diameters ranging from 100 to 400 nm was 0.48 ± 0.03 GPa, which is similar to the modulus of bulk PCL, with no apparent dependence on diameter. Our findings highlight the importance of the assumptions used in the analysis of bending data, as discounting the effects of axial stretch and pre-existing tension typically lead to an overestimate of the Young’s modulus.

Predicting muscle tissue response from calibrated component models and histology-based finite element models

Skeletal muscle is an anisotropic soft biological tissue composed of muscle fibres embedded in a structurally complex, hierarchically organised extracellular matrix. In a recent work (Kuravi et al., 2021) we have developed 3D finite element models from series of histological sections. Moreover, based on decellularisation of fresh tissue samples, a novel set of experimental data on the direction dependent mechanical properties of collagenous ECM was established (Kohn et al., 2021). Together with existing information on the material properties of single muscle fibres, the combination of these techniques allows computing predictions of the composite tissue response. To this end, an inverse finite element procedure is proposed in the present work to calibrate a constitutive model of the extracellular matrix, and supplementary biaxial tensile tests on fresh and decellularised tissues are performed for model validation. The results of this rigorously predictive and thus unforgiving strategy suggest that the prediction of the tissue response from the individual characteristics of muscle cells and decellularised tissue is only possible within clear limits. While orders of magnitude are well matched, and the qualitative behaviour in a wide range of load cases is largely captured, the existing deviations point at potentially missing components of the model and highlight the incomplete experimental information in bottom-up multiscale approaches to model skeletal muscle tissue.

Direct measurement of the direction-dependent mechanical behaviour of skeletal muscle extracellular matrix

This paper reports the first comprehensive data set on the anisotropic mechanical properties of isolated endo- and perimysial extracellular matrix of skeletal muscle, and presents the corresponding protocols for preparing and testing the samples. In particular, decellularisation of porcine skeletal muscle is achieved with caustic soda solution, and mechanical parameters are defined based on compressive and tensile testing in order to identify the optimal treatment time such that muscle fibres are dissolved whereas the extracellular matrix remains largely intact and mechanically functional. At around 18 h, a time window was found and confirmed by histology, in which axial tensile experiments were performed to characterise the direction-dependent mechanical response of the extracellular matrix samples, and the effect of lateral pre-compression was studied. The typical, large variability in the experimental stress response could be largely reduced by varying a single scalar factor, which was attributed to the variation of the fraction of extracellular matrix within the tissue. While experimental results on the mechanical properties of intact muscle tissue and single muscle fibres are increasingly available in literature, there is a lack of information on the properties of the collagenous components of skeletal muscle. The present work aims at closing this gap and thus contributes to an improved understanding of the mechanics of skeletal muscle tissue and provides a missing piece of information for the development of corresponding constitutive and computational models.

Diagnosis of Muscle Diseases at the Molecular Level With a Passive Constitutive Theory for a Single Muscle Fiber

Titins are mainly responsible for passive mechanical properties of single muscle fibers, which, however, can be compromised by the change in molecular structures of titins occurring in some muscle-related diseases. Based on molecular structures of titins within a sarcomere unit, we have developed a constitutive theory for the passive elasticity of single muscle fibers. The theory prediction is in agreement with experiment. With the utilization of the theory, we demonstrate that abnormal structural parameters of titins from patients with chronic obstructive pulmonary disease or muscle atrophy caused by long-term disuse can be extracted. We then suggest that this constitutive theory may facilitate the molecular diagnosis of muscle diseases exhibiting abnormality in the passive elasticity.

Mechanical Properties of Single Muscle Fibers: Understanding Poor Muscle Quality in Older Adults with Diabetes.

BackgroundWhile aging causes muscle weakness, type 2 diabetes mellitus (T2DM) is also considered a high-risk factor for the induction of skeletal muscle weakness. Previous studies have reported increased collagen content in insulin-resistant skeletal muscles. Here, we studied the mechanical properties of aged skeletal muscle in patients with T2DM to investigate whether aged skeletal muscles with T2DM induce higher passive tension due to the abundance of extracellular matrix (ECM) inside or outside of the muscle fibers. MethodsSamples from the gluteus maximus muscles of older adults with diabetes (T2DM) and non-diabetic (non-DM) older adults who underwent elective orthopedic surgery were collected. Permeabilized single muscle fibers from these samples were used to identify their mechanical properties. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to quantify titin and fiber type distributions in these samples. ResultsWe confirmed a significant predominance of type I fiber ratio in both T2DM and non-DM aged muscles. While the average cross-sectional area and maximal active tension of the single fibers were smaller in the T2DM group than those in the non-DM group, the difference was not statistically significant. T2DM subjects showed significantly greater passive tension and lower titin-/ECM-based passive tension ratios than those in non-DM subjects, which indicated that more ECM but less titin contributed to the total passive tension. ConclusionBased on our findings, we concluded that T2DM may cause increased passive stiffness of single skeletal muscle fibers in older adults because of an excessive accumulation of ECM in and around single muscle fibers due to increased insulin resistance.

Humidity Controlled Mechanical Properties of Electrospun Polyvinylidene Fluoride (PVDF) Fibers

Processing parameters in electrospinning allow us to control the properties of fibers on a molecular level and are able to tailor them for specific applications. In this study, we investigate how relative humidity (RH) affects the mechanical properties of electrospun polyvinylidene fluoride (PVDF). The mechanical properties of single fibers were carried out using a specialized tensile stage. The results from tensile tests were additionally correlated with high-resolution imaging showing the behavior of individual fibers under tensile stress. The mechanical characteristic is strongly dependent on the crystallinity, chain orientation, and fiber diameter of electrospun PVDF fibers. Our results show the importance of controlling RH during electrospinning as the mechanical properties are significantly affected. At low RH = 30% PVDF fibers are 400% stiffer than their counterparts prepared at high RH = 60%. Moreover, the vast differences in the strain at failure were observed, namely 310% compared to 75% for 60% and 30% RH, respectively. Our results prove that humidity is a crucial parameter in electrospinning able to control the mechanical properties of polymer fibers.

Experimental research on free settling properties of different types of single fiber particle in air

During the industrial production, various fiber particles can be generated and disperse into the air during production process. They can make adverse effects on various aspects such as the air quality when settling slowly in air. Thus, the free settling property should be researched to avoid those adverse influence. In the present work, settling properties of single fibers (cotton, jute, and glass) in air were investigated experimentally under different morphological parameters and moisture absorption rates. The orientation of each fiber at the start of the experiment was horizontal. The results show that there are obvious differences among these three types of fibers due to significant differences on gravitational force, and the settling velocities are in the order, jute > glass > cotton. The monotonous change of the settling velocity for all types of fiber under length condition indicated that the settling velocity of cotton fiber doesn't always increases with length due to the factor of orientation distribution, and neither the increment nor the decrement of the settling velocity is obvious, indicating the settling velocity doesn't vary significantly with length that is at the range of 5 mm–20 mm. In addition, the settling property of present study was also compared with that of existing research under the approximate ReL(Reynolds number based on fiber length). When the moisture absorption rate increases from 4.7% to 13.1%, the increase in mass leads to a slight increase in the settling velocities of both cotton and jute fibers.

Quantitative multi-scale characterization of single basalt fibres: Insights into strength loss mechanisms after thermal conditioning

This article presents an experimental investigation to quantify the effects of high temperature exposure (400–600 °C) on the mechanical properties of single basalt fibres. To this purpose, a combination of single edge notch tension and nanoindentation micro-pillar splitting methods was used to provide an assessment of the fracture toughness of as-received and thermally treated basalt fibres. Similar values were obtained by the two different methods, and interestingly both highlighted an increase in KIc after heat treatment, up to 22% after exposure at 600 °C for 1h (1.59±0.06MPam). The increase in KIc suggests that microstructural changes occur in the fibres, as confirmed by high-speed nanoindentation mapping. Local radial heterogeneity in the fibre structure and elastic modulus and, possibly, the loss of defect orientation originally induced during the fibre drawing process are envisaged to control the decay of basalt fibres tensile strength during high temperature exposure, mimicking a thermal recycling process for composites.

Nanoscale piezoelectric effect of biodegradable PLA-based composite fibers by piezoresponse force microscopy

The piezoelectricity of the biocompatible and biodegradable polymer polylactic acid (PLA) was investigated as a potential magnetoelectric (ME) nanocomposite for biomedical applications. A key focus was to quantify the piezoelectric properties of single PLA fibers while tuning their polymer degradability through the addition of faster degrading polymer, poly (DL-lactide-co-glycolide) (PLGA), which is not a piezoelectric polymer. Piezoresponse Force Microscopy (PFM) showed that electrospun PLA fibers gave a piezoelectric response of 186 ± 28 pm. For comparison both PLA/PLGA (75/25) and PLA/PLGA (50/50) fibers gave significantly lower piezoelectric responses of 89 ± 12 pm and 50 ± 9.1 pm, respectively. For the highest content PLGA fibers, PLA/PLGA (25/75), only very few fibers exhibited a low response of 28 pm while most showed no response. Overall, an increasing PLGA content caused a decrease in the piezoelectric response, thus an expected trade-off existed between the biodegradability (i.e. PLA to PLGA content ratio) versus piezoelectricity. The findings were considered significant due to the existence of piezoelectricity in a tuneable biodegradable material that has potential to impart piezoelectric induced effects on biointeractions with the surrounding biological environment or drug interactions with the polymer to control the rate of drug release. In such applications, there is an opportunity to magnetically control the piezoelectricity and henceforth PLA/CoFe2O4 ME nanocomposite fibers with 5% and 10% of CoFe2O4 nanoparticles were also investigated. Both 5% and 10% PLA/CoFe2O4 nanocomposites gave lower piezoelectric responses compared to the PLA presumably due to the disturbance of polymer chains and dipole moments by the magnetic nanoparticles, in addition to effects from the possible inhomogeneous distribution of CoFe2O4 nanoparticles.

The Protective Role of Bark and Bark Fibers of the Giant Sequoia (Sequoiadendron giganteum) during High-Energy Impacts.

The influences of (1) a high fiber content, (2) the arrangement of fibers in fiber groups, and (3) a layered hierarchical composition of the bark of the giant sequoia (Sequoiadendron giganteum) on its energy dissipation capability are analyzed and discussed regarding the relevance for an application in bioinspired components in civil engineering. The giant sequoia is native to the Sierra Nevada (USA), a region with regular rockfalls. It is thus regularly exposed to high-energy impacts, with its bark playing a major protective role, as can be seen in the wild and has been proven in laboratory experiments. The authors quantify the fundamental biomechanical properties of the bark at various length scales, taking into account its hierarchical setup ranging from the integral level (whole bark) down to single bark fibers. Microtensile tests on single fibers and fiber pairs give insights into the properties of single fibers as well as the benefits of the strong longitudinal interconnection between single fibers arranged in pairs. Going beyond the level of single fibers or fiber pairs, towards the integral level, quasistatic compression tests and dynamic impact tests are performed on samples comprising the whole bark (inner and outer bark). These tests elucidate the deformation behavior under quasistatic compression and dynamic impact relevant for the high energy dissipation and impact-damping behavior of the bark. The remarkable energy dissipation capability of the bark at the abovementioned hierarchical levels are linked to the layered and fibrous structure of the bark structurally analyzed by thin sections and SEM and µCT scans.

Software simulation for the study of the fiber optic properties and its impact on the output power

The planning fiber optic properties are one of the important fields in fiber optic communication systems. In this article a software simulation proposed to study the main properties of single mode fiber and impact on the output power. This is because fiber optics has many advantages, including a small transmission loss, so it is used for high-speed data transmission. Dispersion is the main factor limiting performance. By simulating an optical communication device model and using the system's most suitable settings that include power inputs (dB), the length of the optical cable (km) and attenuation coefficient (dB /km) which belongs to the fiber optics, different parameters were calculated in this project, including the recipient's decibel energy. From the monitors at the end of transmission link like as (OTDV, OSA, and WDM Analyzer) the overall system behaviors show good results

Tensile Properties of Single Cellulosic Bamboo Fiber (Gigantochloa Scortechinii) Using Response Surface Methodology

ABSTRACT Gigantochloa scortechinii is one of the most well-known bamboo species in Malaysia because of its advantageous physical, morphological and strength properties. This study presented the effect of alkali treatment conditions of single cellulosic bamboo strips fiber following tensile test and optimized the parameters through response surface methodology based on central composite design. Bamboo strips fiber was treated under various alkali concentrations of 2, 4, 6 and 8 wt.% and soaking times of 1, 3, 6, 12, 18 and 24 h. Results showed that the optimum tensile strength at 4 wt.% alkali concentration and 12 h soaking time was improved by 28% compared with water retting condition. The design-Expert software was used to optimize the tensile properties of single cellulosic bamboo strips fiber. The effect of two independent variables, namely, alkali concentration and soaking time, on the optimized tensile properties of a single cellulosic bamboo strips fiber was investigated. Results showed acceptable R2 and high R2 Adj correlation coefficients for tensile strength, reaching 0.6926 and 0.9575, respectively. The high R2 and R2 Adj correlation coefficients for tensile modulus reached 0.9376 and 0.8931, respectively. Overall results showed that the confirmatory experiments show that the error between predicted and actual values does not exceed 5%. thus, the model can be effectively used to predict tensile properties.

Non-linear Scaling of Passive Mechanical Properties in Fibers, Bundles, Fascicles and Whole Rabbit Muscles.

Defining variations in skeletal muscle passive mechanical properties at different size scales ranging from single muscle fibers to whole muscles is required in order to understand passive muscle function. It is also of interest from a muscle structural point-of-view to identify the source(s) of passive tension that function at each scale. Thus, we measured passive mechanical properties of single fibers, fiber bundles, fascicles, and whole muscles in three architecturally diverse muscles from New Zealand White rabbits (n = 6) subjected to linear deformation. Passive modulus was quantified at sarcomere lengths across the muscle’s anatomical range. Titin molecular mass and collagen content were also quantified at each size scale, and whole muscle architectural properties were measured. Passive modulus increased non-linearly from fiber to whole muscle for all three muscles emphasizing extracellular sources of passive tension (p < 0.001), and was different among muscles (p < 0.001), with significant muscle by size-scale interaction, indicating quantitatively different scaling for each muscle (p < 0.001). These findings provide insight into the structural basis of passive tension and suggest that the extracellular matrix (ECM) is the dominant contributor to whole muscle and fascicle passive tension. They also demonstrate that caution should be used when inferring whole muscle properties from reduced muscle size preparations such as muscle biopsies.

An approach to analyse the factors behind the micromechanical response of 3D-printed composites

The state-of-the-art process for additive manufacturing of continuous-fibre reinforced polymers is fused filament fabrication (FFF), which has potential for reproducing robust and complex geometries. However, at the present, the mechanical performance of the resulting parts is affected by the low adhesion between layers and the high concentration of voids. This article proposes a characterisation approach to obtain describing factors for the contribution of composite constituents to the micromechanical behaviour of 3D printed composite materials. The methodology encompasses the examination of: (i) single fibre properties, (ii) fibre distribution and content and (iii) polymer nature. In doing so, this works attempts to standardise this methodology to obtain a more systematic and quantitative approach to this topic, promoting comparative research of additive manufacturing of commercially available continuous reinforced polymers. Although inhomogeneous fibre volume fractions observed in the microstructure may lead to trigger premature failure of the materials, calorimetric properties of polymer matrices might be the underlying factors of the relatively low mechanical response of additive manufactured composites. Taking into account manufacturing constrains, different strategies to enhance the mechanical performance of printed composites are proposed in the paper.

Predicting the macroscopic response of electrospun membranes based on microstructure and single fibre properties

In the present paper, the three-dimensional structure and macroscopic mechanical response of electrospun poly(L-lactide) membranes is predicted based only on the geometry and elasto-plastic mechanical properties of single fibres supplemented by measurements of membrane weight and volume, and the resulting computational models are used to study the non-affine micro-kinematics of electrospun networks. To this end, statistical parameters describing the in-plane fibre morphology are extracted from scanning electron micrographs of the membranes, and computational network models are generated by matching the porosity of the real mats. The virtual networks are compared against computed tomography scans in terms of structure, and against uniaxial tension tests with respect to their macroscopic mechanical response. The obtained virtual network structure agrees well with the fibre disposition in real networks, and the rigorous prediction of the mechanical response of two membranes with mean diameters of 1.10μm and 0.70μm captures the experimental behaviour qualitatively. Favourable quantitative agreement, however, is obtained only after lowering the Young's moduli, yield stresses and hardening slopes determined in single fibre tests, and after reducing the density of inter-fibre bonds in the model of the membrane with thinner fibres. The simulations thus demonstrate the validity and merits of the approach to study the multi-scale mechanics of electrospun networks, but also point to potential discrepancies between the properties of electrospun fibres within a network and those produced for single fibre characterisation, and highlight the existing uncertainty on the density and quality of bonds between fibres in electrospun networks.

Transverse compressive properties of natural fibers determined using micro mechatronic systems and 2D full-field measurements

The literature focusing on the transverse mechanical properties of single fibers is very sparse compared to those related to longitudinal properties. An original characterization method is proposed herein, relying on a micro mechatronics device to implement a transverse compression test which is monitored using 2D full-field measurements. This is shown to allow for the identification of the transverse elastic properties of a single fiber. The method is used, at first, on a bio-based polymer monofilament (PA11) which is assumed to have regular and controlled dimensions and geometry. The transverse elastic modulus is identified to be equal to approximately 1500 MPa and the longitudinal modulus 2150 MPa. The proposed method is then used to investigate the transverse compressive behavior of contrasted natural fibers, such as beard hair (protein-based) and sisal fibers (polysaccharides-based) which have more complex shape and/or internal structure. This paper gives for the first time the compressive force displacement curves as well as the monitoring of the shape of the cross-section during the loading.