Mechanical Properties Of Fibers Research Articles

Uniaxial carbon nanotube fiber reinforced dielectric elastomer actuator with self-sensing

Compared to the isotropic dielectric elastomer (DE), uniaxial fiber reinforced DEs have larger deformation capabilities in specific directions, showing great application prospects. However, there are still significant challenges in achieving self-sensing without introducing additional sensing components. Inspired by the control method of biological muscles, in this article, we used carbon nanotube (CNT) fibers as reinforcing fibers that resistance changes are highly sensitive to tensile strain and exhibit a linear relationship within a small strain range. Based on the developed uniaxial reinforced strain behavior model of DEs, a shear lag model was adopted to introduce an interface transition layer between the DEs and CNT fiber to consider the strain difference caused by the difference in elastic modulus. The relationship between CNT fiber strain and DE strain was established, and the influence of CNT fiber mechanical properties on self-sensing performance was explored. The verification results under 0.05 Hz, 20 kV/mm signals show that the model has 4 % error, providing new ideas for the self-sensing function of uniaxial fiber reinforced DEs.

Experimental investigation on mechanical properties of fiber recycled concrete filled-square steel tube columns under pure flexural based on acoustic emission technique

Currently, global countries are actively focusing on carbon emission reduction. Utilizing recycled aggregate concrete (RAC) is expected to realize global carbon neutrality objectives. However, due to its inherent mechanical limitations, its application in structural contexts is restricted. This study aimed to enhance the mechanical attributes of RAC and expand its utility beyond low-strength applications. By employing recycled aggregates, steel fibers, and ordinary Portland cement, a novel eco-friendly composite filler was developed for steel- tube filling. A comprehensive study on 16 concrete mix ratios and 23 steel-tube recycled concrete columns was conducted. The parameters included the recycled aggregate volume, steel fiber content, and steel pipe thickness. The results revealed that reasonable mix design enabled RAC to exhibit flexural performance similar to that of conventional steel-tube concrete. Moreover, while increasing the recycled aggregate content deteriorated the overall mechanical properties, incorporating steel fibers extended the elastic stage and enhanced the flexural characteristics. Optimal results were achieved with 1.2 % steel fiber addition and 75 % recycled aggregate. The comparison between the derived equation and the experimental data demonstrated a high level of agreement, confirming the accuracy of the equation. Furthermore, acoustic emission technology was employed in this experiment to monitor the failure progression of steel tube recycled concrete columns subjected to a pure bending load. The findings revealed a triphasic failure process: elastic, elastic-plastic, and strengthening stages. The analysis demonstrated a consistent correlation between acoustic emission parameters and waveform characteristics with the failure process of the specimen. Empirical evidence demonstrated the efficacy of acoustic emission technology in effectively monitoring the damage severity and failure chronology in recycled concrete steel pipe columns during bending.

Biomimetic Spider Silk by Crosslinking and Functionalization with Multiarm Polyethylene Glycol

AbstractSpider silk is renowned for its exceptional mechanical properties, surpassing those of other natural and many synthetic fibers. Yet, replicating its remarkable properties through synthetic production remains a challenge. The variability in the mechanical properties of synthetic spider silks lacking protective coatings, exacerbated by factors such as spinning conditions and humidity levels, poses an additional challenge, impacting their application potential. Bioconjugation offers a versatile synthetic method to modify protein structures, enhancing their pharmacokinetics, solubility, stability, and immune response. In particular, polyethylene glycol (PEG)‐ylation has emerged as a successful strategy with numerous marketed PEG–protein conjugates. This study introduces synthetic spider silk—multiarm PEG bioconjugates, facilitating spidroin crosslinking, and chemical functionalization while retaining a biomimetic spinning approach. Two different examples demonstrate the potential of this approach to improve the fiber's tensile strength and extensibility, respectively, both leading to an increased toughness modulus. Furthermore, the approach could allow the tuning of fiber mechanical properties without developing a new mini‐spidroin construct and fiber coating with lipids attached to multiarm PEG, potentially mitigating the impact of environmental conditions on synthetic spider silk fibers.

Effects of MgO on the fibre spinnability, mechanical properties and acid resistance of simulated Martian soil

The ultimate goal of Mars exploration is to construct a Mars base. In particular, it is necessary to prepare fibres by using Martian soil as a raw material. High-strength "Martian glass fibres" can be used to reinforce composite materials to meet the requirements of high-strength functional materials in base construction. Owing to the wide variation in MgO content in Martian soil, in this study, the effects of MgO on the structure, strength and acid resistance of "Martian glass and glass fibres" were investigated. The preparation conditions and mechanical properties of simulated Martian soil fibre (SMSF) were studied via DSC, XRD, Raman, NMR, FT-IR and high-temperature rotational viscometry. The corrosion behaviour of MgO-SMSF in H2SO4 solution was subsequently studied via SEM/EDS. The results showed that MgO reduces the spinnability window and prevents the fibres from stretching continuously, and a threshold appears to exist at 10.89 % MgO. The viscosity of the melt decreased significantly, and the crystallization trend increased with MgO above the threshold. The fibre tensile strength showed a nonlinear relationship with a 22.85 % increase in the fibre tensile strength at 9.24 % MgO. SEM/EDS revealed that the surface of the SMSF formed a gel layer, and the mass retention of the MgO-SMSF in the H2SO4 solution reached 90.17 %. The corrosion of SMSF under acidic conditions was controlled by ion diffusion, with Mg+ and Ca+ diffusing to the fibre surface, resulting in nonuniform corrosion. Raman-based statistical structureproperty modelling further explains the impact of MgO-induced structural changes on the tensile strength and elastic modulus, with good agreement between the model predictions and measured values.

In-situ WAXS and SAXS microstructural investigation of Poly(vinylidene fluoride)- Fe3O4 coaxial-electrospun nanocomposites under thermal and mechanical loading: Nanoparticles size effects on fibers molecular orientation, mechanical properties and crystalline polymorphs

In this study, 15 % w/w polyvinylidene fluoride (PVDF)–Fe3O4 nanoparticle (NP) nanocomposite scaffolds were prepared using coaxial electrospinning with a high-speed conductive rotating collector to obtain aligned fibers. The effects of varying the Fe3O4 NP size (6, 9, and 14 nm in diameter) on the fiber morphology, mechanical response, and piezoelectric phase content were investigated. In situ X-ray diffraction measurements during heating-cooling and tensile tests were carried out using synchrotron radiation to study the charge in the β-phase content and polymer chain orientation under different conditions. At zero strain, the presence of smaller NPs seems to impede the β-phase crystallization in PVDF. However, heating-cooling cycles revealed that the NPs acted as nucleation agents, promoting a higher β-phase content after cooling compared to pure PVDF. The mechanical response showed that nanocomposites with smaller NPs exhibited higher stiffness. While the initial degree of polymer chain orientation was higher in the nanocomposites, the presence of NPs hindered the α-to-β phase transformation and chain alignment under tensile deformation compared to pure PVDF. This study highlights the complex interplay among NP size, β-phase formation, mechanical properties, and chain orientation in PVDF-Fe3O4 nanocomposites, providing insights into tailoring their piezoelectric performance for various applications.

Ultimate resistance and fatigue performance predictions of woven-based fiber reinforced polymers using a computational homogenization method

PurposeIn order to achieve the desired macroscopic mechanical properties of woven fiber reinforced polymer (FRP) materials, it is necessary to conduct a detailed analysis of their microscopic load-bearing capacity.Design/methodology/approachUtilizing the representative volume element (RVE) model, this study delves into how the material composition influences mechanical parameters and failure processes.FindingsTo study the ultimate strength of the materials, this study considers the damage situation in various parts and analyzes the stress-strain curves under uniaxial and multiaxial loading conditions. Furthermore, the study investigates the degradation of macroscopic mechanical properties of fiber and resin layers due to fatigue induced performance degradation. Additionally, the research explores the impact of fatigue damage on key material properties such as the elastic modulus, shear modulus and Poisson's ratio.Originality/valueBy studying the load-bearing mechanisms at different scales, a direct correlation is established between the macroscopic mechanical behavior of the material and the microstructure of woven FRP materials. This comprehensive analysis ultimately elucidates the material's mechanical response under conditions of fatigue damage.

Effect of CNT Oxidation on the Processing and Properties of Superacid-Spun CNT Fibers.

Spinning fibers from carbon nanotube (CNT)/superacid dispersions has emerged as a promising strategy for industrial-scale production of high-performance CNT fibers (CNTFs). The oxygen content and types of functional groups on CNT surfaces significantly influence dispersion, assembly processes, and fiber properties. In this study, Tuball-SWCNTs were purified and oxidized at varying levels. The dispersion behavior of CNTs with different oxidation levels in chlorosulfonic acid was systematically observed, and the mechanical properties of fibers spun from these dispersions were compared. By adjusting the dispersion concentration, highly oriented CNTFs were produced with a specific strength of 1.03 N/tex, a tensile strength of 1.59 GPa, and an electrical conductivity of 3.58 MS/m. Further investigations indicated that oxygen-containing functional groups decrease the coagulation rate, increasing the maximum draw ratio during spinning and improving CNT alignment in the fibers. Molecular dynamics simulations demonstrated that these functional groups (-OH, -COOH) enhance load transfer between CNTs through hydrogen bonding. This specific strength is the highest achieved using Tuball-SWCNTs for superacid-spun fibers, surpassing previous works due to the oxidation-controlled coagulation rate, enhanced fiber orientation, and improved load transfer via hydrogen bonding. This study provides insights for designing and optimizing high-performance CNTFs.

Preparation and characterization of high load‐bearing needled composite preform based on novel ordered short fiber network needling method

AbstractNeedled preform and its composite using felt and base cloth stacked needled have small fiber volume fraction and relatively weak mechanical properties, which are difficult to meet the service requirements of structural and functional integrated components of high‐speed aircraft. Responding to this issue, this paper proposed a new method for preparing high load‐bearing needled composite preform based on ordered short fiber network needling. The high load‐bearing needled preforms were prepared by designing different structural parameters of ordered short fiber network and forming process parameters, and then preform structure was characterized and mechanical properties were tested. The results showed that using ordered short fiber network as carrier of the short fibers, the formed needled fiber bundles were longer and denser, volume content of needled fiber bundles and mechanical properties of needled preform were greatly improved, and needled fiber bundles volume content of ordered short fiber network reinforced needled preform was 1.5 times and 46.3 times that of half‐cut cloth and felt respectively. Compared with traditional felt needled preform and half‐cut cloth needled preform, the interlaminar peeling strength of the ordered short fiber network reinforced needled preform increased by up to 246.4% and 49.2%, respectively. The tensile strength of ordered short fiber network reinforced needled preform was 12.9% higher than that of half‐cut cloth in X‐axis direction. In addition, the effects of ordered short fiber network structure, short fiber length, areal density and needling density on the needled preform structure and properties were also revealed.Highlights High load‐bearing needled composite preform was prepared based on novel ordered short fiber network needling method. The needled fiber bundles formed by using ordered short fiber network were longer and denser, and their volume content was 46.3 times that of felt needled preform. The interlaminar peeling strength of the ordered short fiber network reinforced needled preform increased by up to 246.4%. The tensile strength of ordered short fiber network reinforced needled preform was 12.9% greater than half‐cut cloth in the X‐axis direction.

Extracting and characterizing novel cellulose fibers from Chamaerops humilis rachis for textiles' sustainable and cleaner production as reinforcement for potential applications

New cellulose (CL) fibers are derived from Chamaerops humilis (Ch) rachis. They play an essential role in various industries to produce environmentally friendly products as an alternative to enhancing and strengthening lightweight composites, such as dashboards automotive. Distinctive properties of Ch fibers (ChFs) were determined by extracting fibers from dwarf palm plant branches using anaerobic analysis. This search comprehensively studies morphological, physical, mechanical, and thermal characteristics and water absorption testing. The fiber diameter was 241.23 ± 34.77 μm, while the obtained linear density and density were 13.71 ± 0.57 Tex and 0.801 ± 0.05 g/cm3, respectively. The moisture content was 8.5 %, and the moisture regain was 9.29 %. Scanning electron microscopy images showed the fibers and smooth and rough surfaces. The thermogravimetric analysis demonstrated the maximum degradation of 352 °C, thermal stability of 243 °C, and the kinetic activation energy reached (79.78 kJ/mol). X-ray diffraction proves the availability of CL, with a crystallinity index = 68.38 % and crystal size = 2.92 nm. Fourier transform infrared succeeded in detecting functional groups and chemical compounds of fibers. The fibers exhibited a tensile stress of 110.85 ± 77.08 MPa, an elongation at a break rate of 2.29 ± 1.27 %, and Young's modulus of 6.05 ± 3.9 GPa. The maximum likelihood method (2P-Weibull distribution) was employed to examine the distribution of mechanical properties of fibers. According to the results above, new ChFs are an excellent reinforcement for elaborating fiber-reinforced biocomposites.

Surface-engineered in-situ fibrillated thermoplastic polyurethane as toughening reinforcement for geopolymer-based mortar

Geopolymer composites often exhibit severe brittle failure when subjected to tensile and flexural loads, mainly owing to their inherently ceramic-like structure. Therefore, this study aims to overcome the previously mentioned weaknesses by introducing 2 wt% of surface-modified, in-situ fibrillated Co-PP (copolymer of polyethylene (PE) and polypropylene (PP))/thermoplastic polyurethane (TPU) blend to produce fiber-reinforced geopolymer mortars. The fiber-in-fiber Co-PP/TPU was first fabricated using spunbond, then functionalized using a mild, two-step, one-pot chemical surface modification process. A comprehensive and detailed study of the fibers' chemical structure, morphology, and mechanical properties has been conducted. As well as their impact on the geopolymer mortars' mechanical performances. Moreover, incorporating the modified fibers dramatically increased the flexural toughness and strength at failure of the composite, reaching up to 1600 % and 280 % compared to the control sample, respectively. Furthermore, the flexural modulus was improved by 2 folds. Additionally, the split tensile and compressive strength were improved by 84 % and 17 %, respectively. These findings and the SEM images of the fractured samples indicate the presence of several toughening mechanisms, associated with an improved matrix-fiber interface and an enhanced growth of geopolymer products around the fiber's surface.

Plastic deformation of the microfibrils in wet polyacrylonitrile fibers induced by the stretching field

AbstractThe plastic deformation of the microfibrils governs the formation and development of orientation, crystallization, and structural defects in polyacrylonitrile (PAN) fibers due to the flow‐fiber coupling effect during stretching process. In this study, we investigated the morphological changes of microfibrils in PAN fibers during wet‐fiber stretching using ultrathin section technology and electron microscopy observation. Their plastic deformation mechanism was also revealed. An interconnected network was formed and separated by the pore/voids during coagulation process. Stretching forces facilitated the plastic deformation of microfibrils, resulted in their elongation and orientation. Moreover, the inter‐fibril distance reduced and pore/void shape and dimensions were changed. The distinct response of microfibril elements under stretching force resulted in skin‐core structures within the fiber. Tensile strength increased from 27 to 382 MPa, while elongation at break decreased from 225% to 28%. Aligned microfibrils exhibited high tensile strength, whereas unoriented microfibrillar networks showed relatively high elongation properties. Additionally, we proposed a relationship between microfibril morphology changes and fiber mechanical properties.

Analyzing fiber and vascular bundle characteristics, and micro-mechanical properties of Oligostachyum sulcatum

The structure of vascular bundles and the mechanical properties of fibers are crucial factors determining the utilization of bamboo. This study investigated the structure of vascular bundles and evaluated the morphological and micromechanical properties of the fibers in Oligostachyum sulcatum. The results showed that the fiber length and width of O. sulcatum meet the requirements of raw materials for the papermaking process. However, the fiber content in O. sulcatum is relatively low, which may increase the cost of papermaking. The vascular bundle growth exhibited non-uniformity, especially at the top part, with no discernible pattern in bundle area changes. The nanoindentation testing demonstrated that the bamboo’s indentation modulus of elasticity (IMOE) and hardness values were comparable to those of moso bamboo (Phyllostachys edulis), suggesting its potential as a substitute in engineering applications.

Degree of Cure, Microstructures, and Properties of Carbon/Epoxy Composites Processed via Frontal Polymerization.

The frontal polymerization (FP) of carbon/epoxy (C/Ep) composites is investigated, considering FP as a viable route for the additive manufacturing (AM) of thermoset composites. Neat epoxy (Ep) resin-, short carbon fiber (SCF)-, and continuous carbon fiber (CCF)-reinforced composites are considered in this study. The evolution of the exothermic reaction temperature, polymerization frontal velocity, degree of cure, microstructures, effects of fiber concentration, fracture surface, and thermal and mechanical properties are investigated. The results show that exothermic reaction temperatures range between 110 °C and 153 °C, while the initial excitation temperatures range from 150 °C to 270 °C. It is observed that a higher fiber content increases cure time and decreases average frontal velocity, particularly in low SCF concentrations. This occurs because resin content, which predominantly drives the exothermic reaction, decreases with increased fiber content. The FP velocities of neat Ep resin- and SCF-reinforced composites are seen to be 0.58 and 0.50 mm/s, respectively. The maximum FP velocity (0.64 mm/s) is observed in CCF/Ep composites. The degree of cure (αc) is observed to be in the range of 70% to 85% in FP-processed composites. Such a range of αc is significantly low in comparison to traditional composites processed through a long cure cycle. The glass transition temperature (Tg) of neat epoxy resin is seen to be approximately 154 °C, and it reduces slightly to a lower value (149 °C) for SCF-reinforced composites. The microstructures show significantly high void contents (12%) and large internal cracks. These internal cracks are initiated due to high thermal residual stress developed during curing for non-uniform temperature distribution. The tensile properties of FP-cured samples are seen to be inferior in comparison to autoclave-processed neat epoxy. This occurs mostly due to the presence of large void contents, internal cracks, and a poor degree of cure. Finally, a highly efficient and controlled FP method is desirable to achieve a defect-free microstructure with improved mechanical and thermal properties.

Investigating long term storage stability and drug release behavior of polypeptide based fibrous scaffold for tissue engineering application

Electrospun poly (γ-benzyl-l-glutamate) (PBG) scaffold felt with aligned fibers shows promising nerve regeneration and neurite growth capability due to the nerve stimulating moiety of glutamate in the PBG material. The nerve regeneration capability can be further enhanced by incorporating 4 wt% minocycline hydrochloride (MH) in the scaffold (PBGMH4). They are useful in the nerve tissue engineering to repair and regeneration damaged nerves in central nerve system or peripheral nerve system. Here we investigate the ambient storage capability of PBG and PBGMH4 by monitoring the changes over time of fiber dimension, mechanical properties of both scaffolds and amount of drug release of PBGMH4. It is interesting to observe the diameter of fibers and mechanical strength of scaffolds increases but the amount of drug release decrease with time. By carefully examining the top view of the scaffolds using scanning electron microscopy (SEM), the fiber diameter of PBG increased by 58 % over the 12 months storage period, which is larger than the 32 % increase observed for PBGMH4. Furthermore, after storage for 12 months, the difference in fiber diameter between the top and bottom sides of PBG scaffold is 25.9 %, whereas for PBGMH4 is only 6.3 %. These results demonstrate that the PBGMH4 scaffold exhibits superior storage stability compared to that of PBG. Because the fibers of the scaffolds are aligned without any crosslinkage, the scaffolds are porous structure of felts. The porosity of PBGMH4 scaffold is decreased from 90 % to 72 % which can be accountable for the decrease of drug release from initial 42 % to a stabilized 26 % after 9 months of storage. The results indicate the specific surface area of the scaffolds play an important role in governing drug release kinetics. This study thoroughly investigates the storage stability of PBG and PBGMH4 electrospun fibrous scaffolds. The observed correlations between fiber diameter, mechanical properties, and drug release behavior hold implications for the design of advanced bioscaffolds. The long shelf life of optimal PBGMH4 scaffold shows potential application for the nerve regeneration and controlled drug delivery systems.

Influence of Different Retting on Hemp Stem and Fiber Characteristics Under the East of France Climate Conditions

ABSTRACT Historically, for fiber extraction, the stems were immersed in water. However, this method proved far too polluting, leading to its substitution by the dew-retting method in the field. Different retting processes and durations can produce significant differences in hemp stems and fiber characteristics. Both dew- and water-retting methods were carried out on the Santhica 27 cultivar in Eastern France in 2020. An analysis of the stem chemical composition and characteristics has been performed to observe the stem degradation during retting for both methods. Secondly, the analyses of the fiber chemical composition, color, morphological and mechanical properties have been performed to evaluate the impact of retting on the fiber quality. The effect of the retting on the stem and the fiber is observed after 1 week for water-retting and after 4 weeks for dew-retting. For dew-retting, the percentages of fine fiber and cellulose in the fiber bundle increase after 1 week, while the stem chemical composition decreases. Unlike in the dew-retting, the percentage of fine fiber and cellulose in the fiber bundle increases after 4 weeks, while the potassium percentage in the stem, fiber brightness, and fiber tenacity and strain decrease. Finally, after 8 weeks, the fiber properties were found to be similar for both methods.

Experimental Analysis of Mechanical Properties of Fiber Reinforced Cenosphere Lightweight Concrete with Higher Temperature Effect

The aim of this research is to explore the impact of polypropylene fibers and glass fibers on the mechanical characteristics of lightweight concrete when subjected to elevated temperatures. Different fiber ratios ranging from 0.25% & 0.50% by volume of concrete were tested to evaluate their impact on various concrete mixtures. Cenosphere is lightweight material as used with cement as bonding material. Pumice aggregate, which is known for its lightweight properties, was utilized as the coarse aggregate. The study aimed to explore various characteristics of lightweight concrete such as slump value, unit weight, and compressive, tensile, and flexural strength. The concrete samples were subjected to different temperatures ranging from 200°C to 400°C for two hours. The findings revealed that the addition of glass fibers improved the tensile strength of the concrete and enhanced the compressive and flexural strength of the lightweight concrete. However, the incorporation of polypropylene fibers resulted in more cracks and pore formation in the concrete. Additionally, the compressive and flexural strength of the concrete decreased with an increase in temperature up to 400°C.

Improving the mechanical performance of railway concrete sleepers using recycled materials: An experimental and numerical study

This paper explores the use of three waste materials available in vast quantities, including waste tires, glass bottles and bamboo furniture, in the manufacture of railway sleepers. Mechanical properties of recycled concrete have been studied to establish an optimal mix suitable for concrete railway sleeper manufacturing. Thus, 5%, 10%, 15% and 20% recycled rubber sands (RRS) by volume of fine aggregate are used instead of 30# and 60# mesh sizes of fine aggregate. Moreover, 20%, 40%, 60%, 80% and 100% of aggregate volume are replaced by recycled glass aggregate (RGA) particles. Furthermore, different percentages of recycled bamboo fibers (RBF) have been used as 1%, 2% and 3% by volume of concrete. According to the optimal concrete mixtures of RRS, RGA and RBF, twelve concrete railway sleepers are manufactured and tested for middle and rail seat bending strengths. Results show that ref. sleeper has almost 16% and 24% lower strengths than RGA sleeper in middle and rail seat, respectively, while ref. sleeper have higher strengths by 16% and 13%, and 18% and 7% than RRS sleeper (M60-R5) and RBF sleeper (B2) in middle and rail seat, respectively. The FEM results show that the ([Formula: see text]) of the RGA sleeper is the minimum ratio by 1.11 and 1.13 for rail seat and middle of sleeper, respectively, which is the best performance. In RBF sleeper FEM model, Bamboo fiber can only bear 5% and 8% of total stress in middle and rail seat, respectively, due to low mechanical properties of fibers.

Pulp and Paper Characteristics of Five Lesser-known Species in Kalimantan: Effects of Re-beating

Five lesser-known species from natural forests in Central Kalimantan, viz., cempaka (Michelia champaca Linn), mentawa (Artocarpus rigidus Blume), menjalin (Xanthophyllum excelsum Miq.), kempili (Lithocarpus elegans (Blume) Hatus. Ex Soepadmo), and sempori (Dillenia sp.) were evaluated in the laboratory for their specific gravity, fiber morphology, pulping and papermaking properties. In addition, their properties after three-phase beating were also evaluated from a recycled paper point of view. The specific gravity and fiber length range were 0.58~0.68 and 1239~2479 μm, respectively. The highest value in specific gravity was observed in menjalin wood, while the longest fiber was observed in sempori. Kraft pulping with 14% active alkali (as Na2O), 23% sulfidity, 2 h at the maximum temperature showed that the highest screened yield was determined in cempaka wood (44.29%) with a kappa number of 17.6. The freeness ranges of unbeaten pulp were 675~780m mL CSF. The freeness ranges of 1st, 2nd, and 3rd beating were 539~630 mL, 235~275 mL, and 220~230 mL CSF, respectively. The 1st beating exhibited the best mechanical properties. Among the species, cempaka, kempili, and mentawa showed comparatively high tensile (57~60 Nm/g) and burst index (2.6~3.4 KPa m2/g), whereas the highest value for tear index (5.02 mNm2/g) was observed in sempori. A considerable decrease in fiber length, slenderness ratio, and mechanical properties of the paper was observed with an increased beating number. These findings suggest that cutting the fibers or decreasing the slenderness ratio was the main factor causing the strength to decrease.

Machine learning assisted mechanical properties prediction of fine denier polyester fiber

In recent years, more and more attention has been attracted by fine denier polyester fibers in electronic information industry due to their unique structural and excellent mechanical properties. As known, the mechanical properties of fine denier polyester fibers have a close relationship with their melt-spinning process parameters, thus, it is worth further exploring the influence of process parameters on fiber mechanical properties (namely breaking strength, elongation at break and CV of breaking strength). This study aims to develop a novel prediction model based on the artificial neural network (ANN) to predict the key mechanical properties of fine denier polyester fibers. For this purpose, firstly, different specifications of fine denier polyester fibers with different mechanical properties are produced by adjusting the key melt-spinning parameters, namely spinning temperature, take-roll speed and metering pump speed. Then the experimental data is collected, analyzed and augmented with effect to be used for modeling. Next, a novel prediction model based on ANN is developed by importing the two-streams structure and two attention matrices to improve the feature abstraction for mechanical properties prediction. Lastly, different predictive performance indicators, namely root mean square error (RMSE), mean absolute percent error (MAPE) and the coefficient of determination (R2) are imported to evaluate the proposed model. For the total of three mechanical properties, the predicted results of the proposed model in terms of RMSE, MAPE and R2 are respectively 0.3499, 0.0906 and 2.9516.

Remnant polarization and structural arrangement in P(VDF-TrFE) electrospun fiber meshes affect osteogenic differentiation of human mesenchymal stromal cells

Many tissues and cells are influenced by mechano-electric stimulation, thus the application of piezoelectric materials has recently received considerable attention in tissue engineering. This report investigated electrospun fiber meshes based on poly(vinylidenefluoride-co-trifluoroethylene) [P(VDF-TrFE)] as instructive biomaterials for osteogenic differentiation of human mesenchymal stromal cells (hMSCs). The influence played by methyl ethyl ketone (MEK), used as a solvent in place of dimethylformamide (DMF)/acetone mixture, and the effect of rotating velocity of the electrospinning collector on fiber morphology, mechanical and piezoelectric properties were studied. The solvent had noticeable effects on morphology and piezoelectric properties of electrospun fibers, with MEK outperforming DMF/acetone. By increasing the collector velocity up to 4000 rpm, the fiber diameter reduced and the mutual alignment of the fibers increased, corresponding to enhanced mechanical properties and piezo-active β-phase content. However, as a consequence of the diverse mechanical properties of random and aligned fibrous architectures, which ultimately affected the piezoelectric properties, randomly-oriented fibers exhibited higher remnant piezoelectric properties (Vout and d31 piezoelectric coefficient) than aligned ones. On these scaffolds, hMSCs showed an excellent capability of early osteogenic differentiation, leading to high calcium production. Fiber surface topology, fiber mesh morphology and remnant piezoelectric properties played a determinant role on hMSC osteogenic commitment.