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The main objective of this paper is to investigate the impact splitting tensile property and microstructure characteristics of steel fiber recycled aggregate concrete (SFRAC) based on the split Hopkinson pressure bar (SHPB) and scanning electron microscope (SEM). The effects of fiber content, strain rate, and recycled aggregate replacement ratio on the mechanical parameters (static and dynamic splitting tensile strength, peak strain and ultimate strain, peak toughness and ultimate toughness) were analyzed. Then the microstructure characteristics of SFRAC at different interfaces were observed via SEM, and energy spectrum analysis of the interface transition zone (ITZ) was carried out. The results show that SFRAC is a strain-rate sensitive material whose mechanical properties are affected by the strain rate and improved with its increase. It is also found that steel fibers play a role in improving dynamic splitting tensile strength and toughness, and the optimal fiber content is about 1.0%. However, increasing the recycled aggregate replacement ratio will weaken the good effect of steel fibers on the mechanical properties. Furthermore, it can be seen by means of SEM that the fracture area of steel fiber is mostly pulled out. Also, there are more cracks and pores in the cement paste of recycled aggregate concrete (RAC) compared with normal concrete (NC), and the hydration products in the ITZ are significantly decreased. With the incorporation of steel fibers, the calcium content of the ITZ can be reduced. [ABSTRACT FROM AUTHOR]

Nanoparticles are one of the effective methodologies implemented in concrete technology. The main objective of this research is to study the influence of nano alumina with different percentage variations ranging from 1% to 3% along with the incorporation of PVA fibers. From the mechanical properties test, the optimum dosage was determined to further study the durability behavior. This research work also investigates the hybridization of two nanoparticles such as nano silica (NS) and nano alumina (NA). The results show that the increasing quantity of NA reduces the compressive strength of the mortar due to agglomeration (cluster of particles), which results in a greater molecular attraction force. From the test results, it is concluded that the optimum dosage has been attained with an addition of 2% NA with 0.3% PVA. The compression strength test results at 14 days and 28 days reveal that the addition of NA tends the mineral admixture to react at early ages in the hydration process, which produces a new chemical compound to fill the pores. The rapid chloride penetration (RCPT) test results at 28 days significantly improved with the incorporation of nanoparticles due to their effective size and chemical reaction towards the other compounds. The test results from the hybridization of nanoparticles showed that the compressive strength was significantly enhanced compared to that of the control mortar and mortar with NA. They are effective up to certain limits beyond that addition, and the workability was reduced. Amongst all mixtures, the maximum compression strength has been attained for the mix with the addition of NA 0.5% and NS 2.5% comparatively. The microstructural properties of mortar were also studied through scanning electron microscope (SEM) analysis. The results showed that the incorporation of nanoparticles in the mortar matrix turns homogeneous with fewer pores and greater amount of hydration compounds; thereby, pore refinement has improved the hydration compounds remarkably. [ABSTRACT FROM AUTHOR]

In this paper, the heat treatment of alumina fiber was studied. The infiltration agent on the fiber surface was removed after heat treatment at 450 °C for 6 h. TG-DSC, scanning electron microscope, x-ray diffraction, Fourier infrared spectrometer, energy dispersive spectrometer, and patterning were used to analyze the thermal weight loss, fiber surface morphology, crystal structure, and composition of alumina fibers. The results show that the aluminum oxide fiber has excellent temperature resistance and does not undergo crystal phase transformation during thermal weight loss. After heat treatment, the fiber surface infiltration agent ablates and dissolves from the fiber surface, and the internal crystal structure of the fiber remains stable. The tensile testing machine was utilized to test the breaking strength of alumina fiber. The fiber still maintained high strength after heat treatment, and the retention rate of breaking strength was greater than 74%. ZC-90G high insulation resistance measuring instrument and WDY-Ⅱ automatic voltage tester were utilized to analyze the insulation resistivity and breakdown strength of alumina fiber before and after heat treatment. The results show that heat treatment can effectively improve the insulation performance and breakdown strength of alumina fiber. [ABSTRACT FROM AUTHOR]

The ionic liquid 1‐ethyl‐3‐methyl‐imidazolium acetate (EMIMOAc) is used to develop a wet‐spinning process for the manufacturing of chitosan multifilament yarns on a semi‐industrial pilot scale. Commercial chitosans of different qualities, properties, and deacetylation degree ≤85% are used to prepare of spinning dopes with solids content of 6.0–8.5 wt.% using EMIMOAc as a solvent. The viscometric properties are characterized by rheological tests. The manufacturing of the pure chitosan multifilament yarns of different fineness and filament count from the prepared spinning dopes is performed on a pilot wet‐spinning plant. The obtained yarn properties are evaluated by optical (scanning electron microscope, light microscope), structural (infrared spectroscopy, X‐ray diffraction), and textile‐physical characterization. Chitosan multifilament yarns with high performance, tenacities of ~20–26 cN tex−1 and textile processability in weaving, knitting and braiding processes are manufactured in this work. [ABSTRACT FROM AUTHOR]

In this paper, we conduct a comprehensive investigation into PVA fiber modified with SiO2 to improve the mechanical properties of oil-well cements. Specifically, SiO2 was coated onto the surface of polyvinyl alcohol fiber (PVAF) as its silicon source via a sol-gel process by using tetraethyl orthosilicate (TEOS), while hydrochloric acid and ammonia were respectively used as the catalyst in the sol (hydrolysis) and the gel (condensation) processes. The PVAF microstructure was then characterized with the scanning electron microscope (SEM), while the effects of the modified PVAF on both mechanical and rheological properties of oil-well cements were examined. Due to the fact that SiO2 can be uniformly coated onto the PVAF surface, such modified PVAF can slightly improve the rheology of the cement slurry, while the raw PVAF exhibits poor dispersion at a high dosage. Compared with those of cement stone without PVAF after curing for 28 days at 60 °C, the flexural strength, compressive strength, and elastic modulus of the cement stone incorporated with the modified PVAFs were enhanced by 37.7%, 66.1%, and 50.0%, respectively. The SEM test (EDX) test, XRD test, and thermogravimetric test prove that the SiO2 coating on the PVAF surface can promote the hydration of cement clinker and can react with Ca(OH)2 to generate CSH gel. The SiO2 grafted onto the surface of PVAFs can improve the bond strength at the fiber/cement matrix interface, thus improving the mechanical properties of cement stone. [ABSTRACT FROM AUTHOR]

The lack of concrete tensile stress endurance led to the invention of engineered cementitious composite. However, the absence of gravel from the mixture in addition to the high binder content may lead to high shrinkage strain. Therefore, a radical solution to this problem is worth to be anticipated. The importance of this research lies in investigating the long-term drying shrinkage strain of the engineered cementitious composite since there is a lack of information regarding this behavior. Mixes of 30 and 60 MPa strengths were produced with polyvinyl alcohol fibers PVA-ECC and polypropylene fibers PP-ECC. The drying shrinkage strain of PVA-ECC mixes has been compared to PP-ECC mixes for both short term (0–28 days) and long term (0–360 days). Results indicated that all PVA-ECC mixes exhibited lower drying shrinkage strains than PP-ECC mixes. The ultimate drying shrinkage strain was recorded to be 1200 microstrain at 28 days. The increment in drying shrinkage strain after 28 days was 5.6% in PVA-ECC mixes when compared to that in PP-ECC mixes which was 6.77%. For high strength levels, the drying shrinkage strain at the age of 360 days declared a reduction of 3.5% for PVA-ECC compared to PP-ECC mixes. Also, it was lower for mixes with 60 MPa (6.3%) than for mixes with 30 MPa (7.6%). Therefore, despite the higher cement content for mixes with 60 MPa strength, the higher fiber volume fraction and the higher PVA solution percentage restricted the drying shrinkage strain increment. The research also addresses some mechanical tests of engineered cementitious composite concrete such as compressive strength, flexural strength, and strain capacity that may provide a strong relation to the drying shrinkage behavior of the different mixes. The scanning electron microscope images were involved in this research to declare the impact of fiber types on the microstructure of the ECC mixes. [ABSTRACT FROM AUTHOR]

The performance of cementitious composites reinforced with fibres or/and bars depends on the bond strength between inclusion and cementitious matrix. The nature of formation of fibre‐matrix bond is crucial for enhancing the reliability and utilisation of reinforced composites. The research provides a review on the recently published result about the changes in the microstructure of cement matrix surrounding steel fibres with different surface roughness, using a scanning electron microscope (SEM) coupled with k‐means clustering algorithm for image segmentation. The debonding pattern of the fibre‐matrix bond after the tensile loading cycles was discussed by observing the amount of adhered cement paste to the pulled out fibre surface with SEM. Therefore, analysis of SEM images enabled to explain the connection between the micro‐scale properties of cement paste and fibre after application of cyclic loading. [ABSTRACT FROM AUTHOR]

Controlled development of novel materials fosters innovation in the electrical sector. The hybrid materials based on magnetic nanocellulose are intriguing since they have many uses in electronics, catalysis, medicine, and ecology. The study investigated the structure and morphology of hybrid nanomaterials made from nanocellulose and cobalt ferrite. The nanocellulose was prepared by TEMPO-oxidation and the cobalt ferrite was prepared by sol-gel auto-combustion method. Using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) techniques, it was determined how nanocellulose loading affected the crystal structure of the synthesized composite. To ascertain the variation in the component concentrations, scanning electron microscope (SEM) and energy-dispersive X-ray analysis (EDAX) are used. Composite with a higher concentration of nanocellulose fibers (NCF) show lesser particle size, and this may account for the smaller size of nanocellulose fibers, and attachment of nanocellulose nanofibers over the surface of porous cobalt ferrite (CF) found in SEM images. [ABSTRACT FROM AUTHOR]

In this paper, a safe, non-toxic, and low-cost method was adopted to modify ultra-high molecular weight polyethylene (UHMWPE) fibers. gallic acid (GA) and polyethyleneimine (PEI) were co-deposited on the surface of UHMWPE fibers by Michael addition and Schiff base reaction in an alkaline solution with pH 8.5. The structure and properties were analyzed and characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric Analyzer (TG), etc. The morphology of the UHMWPE fibers and the degree of firmness of the surface coatings were observed by Scanning Electron Microscope (SEM), and the effects of different mass ratios of GA-PEI on the UHMWPE fibers were investigated. The results showed that the surface active functional groups of the modified UHMWPE fibers increased, and the bending properties and interfacial shear strength of the composites with epoxy resin were significantly improved, with the bending strength and interfacial shear strength increased by 33.1% and 45.9%, respectively. [ABSTRACT FROM AUTHOR]

Recently, significant progress has been made in the preparation and properties of fiber-reinforced shells for investment casting; however, the research on the enhancement mechanism of fiber is inadequate. Herein, the composite shell is prepared using the airflow placement fiber process, and the conventional method, preimmersion silica sol and preimmersion slurry methods are adopted to obtain different interfaces between the matrix and fibers. Combined with the directional tensile test and fracture morphology of the shell observed via scanning electron microscope and stereomicroscope, the fiber-reinforced mechanism of the shell is analyzed in detail. It is found that the shell with polypropylene fibers is strengthened by the fiber pull-out, debonding, debonding-deformation and bridging-deformation, even with the different interface bonding between the matrix and fibers. However, the main failure modes of fibers are different under different interface conditions. The fibers in the preimmersion slurry shell mainly fail in the form of debonding-deformation and bridging-deformation, which makes the green strength of composite shells increase significantly. [ABSTRACT FROM AUTHOR]

As a countermeasure to the problem of brittleness of seawater sea sand concrete (SSC), volumetric admixture of glass fiber (GF) and polyvinyl alcohol (PVA) fiber was used as variable, the corresponding specimens were prepared, and the cube compressive strength, splitting tensile strength, axial compressive strength, and elastic modulus were tested. The microstructure of fiber reinforced seawater sea sand concrete was analyzed by scanning electron microscope (SEM) scanning and energy dispersive spectroscopy (EDS) dot scanning, and a model was established based on the grey system theory. The research results show that the fiber can effectively reduce the formation of cracks, leading to a ductile failure of the specimen. In general, the mechanical properties of mixed fiber were improved better than that of single fiber, and the hybrid ratio 2:1 brings a improvement of 24. 2% and 38. 8% for the compressive strength and splitting tensile strength, respectively. The hybrid ratio of 1:1 increases the axial compressive strength and elastic modulus by 34. 5% and 15. 5%. It was observed by SEM and EDS that fiber incorporation could densify the matrix, while the main disadvantage of SSC was that the salt crystallization generated by corrosive ions and swelling substances weakened the bond between aggregate and mortar, resulting in defects of interfacial transition zone (ITZ) . The established NSGM(1, 3) model has a high accuracy, the accuracy reaches class II and conforms to the long-term prediction, which provides a favorable basis for the study of the strength evolution of fiber reinforced seawater sea sand concrete. [ABSTRACT FROM AUTHOR]

The pollution caused by microplastics (MPs) is a growing concern on a global scale, especially considering the significant proportion of time that individuals spend indoors. The contamination in question has the potential to directly impact the human population through exposure to indoor dust and air. This research undertook a comprehensive analysis of the indoor deposition of MPs in university classrooms, employing various investigative tools. The present study aimed to comprehensively analyze the physical and chemical properties of MPs found in university classrooms. Analyzing samples under a stereomicroscope, the predominant MPs were identified as fibers of varied colors, mainly attributed to clothing. Sizes of these MPs varied significantly across different classrooms, with a general average size range of 120–2222 µm. The observed morphological changes in MPs, including cracks and grooves, hint at potential degradation into nanosized plastics over time. This observation raises concerns about increased concentrations of nanoplastics in indoor environments. Using µRaman analysis, eleven types of MPs were identified, potentially originating from clothing, shoes, and stationery. The majority of MPs were polyamide 6, polypropylene, and polyamide 12. The scanning electron microscope and energy-dispersive X-ray spectroscopy (SEM–EDX) technique unveiled the elemental composition of the MPs, with carbon, fluorine, and oxygen being dominant. The findings align with past studies but highlight the need to understand MPs' structural components and any possible contaminants. Compared to existing literature, this study adopts a comprehensive methodological approach combining optical microscopy, µRaman, and SEM–EDX, enriching the knowledge on indoor MP deposition and aiding future research directions. Highlights: Fiber was the dominant type of MP identified. The primary source of fibers is believed to be the clothing worn by students and teachers. The dominant colors were black, transparent, blue, and red. The average range size of MPs is 120–2222 µm. The majority of MPs were identified as polyamide 6, polypropylene, and polyamide 12. Common elements across samples were carbon, fluorine, silicon, and oxygen. [ABSTRACT FROM AUTHOR]

The bond strength between basalt fibers and asphalt binders is an important parameter that can be used to evaluate the influence of basalt fibers on the mechanical properties of asphalt binders and asphalt mixtures. To date, however, there remains a lack of methods that can be used to assess the bond strength between basalt fibers and asphalt binders. This study employed a fiber-asphalt pull-out tester (POT). Significant upward, peak, and downward stages were observed from the relationship curves between the pull-out force (POF) and displacement, corresponding to the holding stage and reaching the maximum POF stage and the sliding or failure stage between fibers and asphalt binders. Maximum POF is recommended to calculate the bond strength between basalt fibers and asphalt binders. The types of asphalt binders suitable for basalt fibers and the appropriate fiber embedding depths for different types of asphalt binders guiding the selection of fiber length are recommended based on the influence of fiber embedding depth and asphalt binders on the fiber–asphalt bond strength. In addition, surface energy was used to calculate the bond strength as well. Surface energy was determined from contact angle measurements using the sessile drop method. Furthermore, a scanning electron microscope (SEM) was employed to examine the bond mechanism between asphalt binders and basalt fibers. These experiments showed how basalt fibers serve to reinforce asphalt mixtures by bonding with asphalt binders. [ABSTRACT FROM AUTHOR]

In this study, 50% iron ore tailings (IOTs) were used to prepare the cemented mortar at low economic costs and with great environmental benefits. Basalt fiber (BF) and polyacrylonitrile fiber (PANF) were added to the tailing mortar to improve the comprehensive performance of tailing mortars, including BF (0~0.5%), PANF (0~0.05%) and the combination of them. The results show that the addition of BF and PANF can significantly improve the ultrasonic velocity, uniaxial compressive strength (UCS), split-tensile strength (STS), flexural strength (FS) and toughness of the tailing mortar. A novel finding is that the enhancement of hybrid fibers is much better than single fiber, and the best hybrid fiber combination is B0.25P0.05 (0.25 wt% BF and 0.05 wt% PANF), because this combination not only causes the most considerable increase in strength but also possesses great cost-effectiveness. Compared to the B0P0 group without fibers, the maximum increments of B0.25P0.05 in UCS, STS and FS are 45.74%, 52.33% and 15.65%, respectively. It is evidenced that the improvement in STS is the largest because the fibers have good cracking resistance and bridging effect in the tailing mortar. The scanning electron microscope (SEM) further confirms that too many hybrid fibers will agglomerate and produce more voids, which is harmful to the development of the internal structure. Beyond B0.25P0.05, the hydration products are also reduced due to the decrease in nucleation sites, observed by combining X-ray diffraction (XRD) tests. Therefore, it is suggested that the hybrid fibers containing 0.25% BF and 0.05% PANF should be used in this tailing mortar. [ABSTRACT FROM AUTHOR]

The tensile behavior of a flexible epoxy resin reinforced with knitted reinforcements from various fiber materials was comprehensively studied in the wale and course direction. By measuring dry yarns, temperature‐treated yarns, dry knitted fabrics and flexible composites, the effect of the fiber material and the knitted fabric on the tensile properties was analyzed. The interlock knit structure strongly affected the deformation behavior of the flexible composites which differed significantly from the dry knitted fabrics. The deformation behavior of the flexible composites was monitored using digital image correlation which revealed the formation of cracks and high local strain differences in the course direction for all fiber materials. This was linked to fiber‐matrix debonding by scanning electron microscope observations. In the wale direction, the deformation of the knitted structure under tensile load led to plastic deformation of the matrix material. Overall, with yarns from recycled thermoplastic fibers, a higher maximum stress and strain at break was achieved compared to bio‐based fibers. However, irreversible damage occurred for all fiber materials at similar strain values. Highlights: Tensile tests on yarns, knitted fabrics and flexible composites.Investigation of the effect of fiber material on mechanical properties.High local strain differences in composites due to knitted structure.Fiber‐matrix debonding in course direction.Plastic deformation of the matrix material in the wale direction. [ABSTRACT FROM AUTHOR]

Fiber-reinforced emulsified asphalt (FEA) is widely used in asphalt pavement structures as a stress-absorption layer. This study aimed at developing a multifunctional fiber-reinforced emulsified asphalt (MFEA) by empowering the FEA with the self-sensing ability. To achieve this purpose, carbon nanotubes (CNTs) were grafted onto the basalt fibers in the FEA. An optical microscope and scanning electron microscope (SEM) were respectively used to investigate the distribution of CNTs onto the fibers and the microstructure of CNT/fiber composite (CFC). The fabrication process of CFC was optimized based on the distribution homogeneity of the CNTs. The self-sensing ability of the MFEA was then evaluated in the laboratory using an electrochemical workstation. Based on the experimental and analytical results, 1.5 mg/mL was recommended as the optimal dosage of the suspension of CNTs for grafting CNTs onto the fiber. The electrical resistance of the developed MFEA was found to be isotropic and sensitive to the demulsification state, EA/CFC mass ratio, temperature, loading speed, and deformation magnitude, which confirms the potential of using developed MFEA as a self-sensing layer to monitor its response to environmental and traffic variation. Besides, the direct tension and pull-out tests indicate the positive influence of grafting CNTs onto basalt fibers on the mechanical performance of FEA. [ABSTRACT FROM AUTHOR]

Large-diameter polyvinyl alcohol (PVA) fiber has a broad application prospect in the field of reinforcing geomorphic building materials owing to its large diameter and excellent mechanical properties. In this work, PVA2499 polymer was used as the raw material, DMSO/H2O as the hybrid solvent, and the staged heating approach was adopted to obtain high solid content of spinning solutions, and then a series of large-diameter medium-strength PVA fibers with different solid contents of spinning solutions (SCS) were prepared by dry-wet spinning, and the Fourier transform infrared spectroscopy (FTIR), scan electron microscope (SEM), differential scanning calorimetry (DSC), thermal analysis (TGA), X-ray diffractometer (XRD) and electronic universal testing machine were performed to explore the effect of the SCS on the structure and performance of PVA fiber. The results displayed that with the increase of the SCS, the -OH stretching vibration absorption peak of PVA fiber moved from 3276 cm−1 to 3262 cm−1; The tensile strength, initial modulus, the crystallization and orientation of PVA fibers all increased first and then decreased. Especially, when the SCS was 23.5wt%, the diameter of the PVA fiber was 110.6 ± 6.0 μm (124.8 ± 6.2 dtex), the tensile strength was 7.0 ± 0.3 cN/dtex, the initial modulus was 106.2 ± 10.3 cN/dtex, the crystallization and the orientation were 49.6% and 96.8%, respectively. [ABSTRACT FROM AUTHOR]

This report presents the preparation and characterization of a new composite containing Prussian blue analogues nanoparticles and poly(N-vinyl-2-pyrrolidone) (PVP). Nanoparticles of nickel hexacyanoferrate (NiHCFe) and nickel hexacyanochromate (NiHCCr) were synthesized by the citrate-assisted co-precipitation method. Basic characterization revealed uniform cubic particles with an average size of 238 nm (NiHCFe) and 80 nm (NiHCCr). In the next step, these nanocubes were incorporated into composite fibres using electrospinning technique. The resulting fibres exhibited distinctive colours, and scanning electron microscope imaging showed differences in fibre morphology between NiHCFe/PVP and NiHCCr/PVP composites. The obtained results indicate the successful synthesis and characterization of Prussian blue analogue nanoparticles, as well as their integration into composite fibres, opening up possibilities for diverse applications. [ABSTRACT FROM AUTHOR]

In this study, basalt fibers (BFs) and nano-silica (NS) were innovatively combined to reinforce recycled aggregate concrete (RAC) to prepare recycled aggregate concrete (named NBRAC) with better mechanical and microstructural properties as an alternative to ordinary concrete. Different NBRAC specimens were prepared by adjusting the contents of NS and BF; the damage mechanism and mechanical properties of NBRAC were investigated; and the compressive, split tensile, and flexural strengths of NBRAC were evaluated. The microstructure of NBRAC was analyzed by scanning electron microscopy observation. The results showed that the densification of NBRAC was improved under the condition of 50% RA substitution rate and that its compressive, split tensile, and flexural strengths were increased by 6.8%, 16.3%, and 32.7%, respectively, compared with that of natural concrete, which proved that the method was feasible for the preparation of high-performance RAC. Scanning electron microscope image analysis confirmed the improvement effects of NS and BF on RAC, and combined with the experimental data, a composite explanation for the improvement effects of NS and BF on RAC was proposed for the first time. [ABSTRACT FROM AUTHOR]

Objective: Age‐related changes in the fiber structure around adipocytes were investigated via scanning electron microscopy (SEM) of excised skin tissues. In addition, the viscoelasticity of the subcutaneous fat layer was evaluated via elastography, and the association between the fiber structure and the viscoelastic properties was assessed. Methods: Skin tissues excised from the facial cheek area were used. Then, SEM images of these tissues were obtained. The thickness and quantity of the fibers around adipocytes were assessed using a 5‐point scale. The score was used to grade 18 tissue samples. Moreover, the viscoelasticity of the subcutaneous fat layer in the same samples was evaluated via ultrasound elastography. Results: Based on the SEM image score, an association was observed between the fiber status score and age, thereby indicating a tendency toward age‐related fibrosis. Fiber structures with high scores, which indicate fibrosis, had a significantly lower viscoelasticity based on ultrasound elastography. Conclusion: The thickness and quantity of fibrous structures around adipocytes in the subcutaneous fat layer increase with age, and these changes can be associated with decreased viscoelasticity in the subcutaneous fat layer. [ABSTRACT FROM AUTHOR]

Identification of archaeological and historical textile fibres is important because it gives insight into resource management in former times. The arrival of new tools such as table-top scanning electron microscopes, have led to an increased interest in the topic. Unfortunately, there have been cases where a lack of documentation regarding instrument settings and selection criteria has led to questionable conclusions being drawn. Optical and scanning electron microscopy are powerful techniques, but they must be used correctly and with proper knowledge of their limitations. Furthermore, ancient fibre material is often difficult to examine due to issues such as sample degradation, mineralization and the scarcity of material, which means that conclusions based on a statistical analysis of a large number of fibres are essentially not possible. In a cultural heritage context, it is therefore essential to distinguish between characteristic features, by which we mean features that are often, but not always present in a particular species and distinguishing features, which are always present in a particular species and can therefore be used for identification even if only a small amount of sample material can be examined. We argue that the community will have to accept that, quite often, a secure identification is not possible and that absolute statements such as: "This textile is made of flax" will often have to be replaced by relative statements such as "The material is likely to be flax". In this paper, we address these issues as follows: first, we present a fibre identification diagram which can be used, with some limitations, to distinguish between flax, hemp, nettle, jute, hops, and cotton using optical and electron microscopy. We then move on to highlight some of the typical pitfalls of using optical and electron microscopy for fibre identification. Finally, we present measurement documentation tables for optical and electron microscopy images, which we suggest should always be included in publications. Material scarcity means that the amount of material used for investigations should be kept at an absolute minimum. It is thus crucial that results are published with proper documentation so that measurements do not need to be repeated (more material is used) in future studies. It is our hope that the measurement documentation tables will be adapted by the community and used in future publications in the field. The paper finishes with a demonstration example, presenting a fibre analysis of Viking Age textile fragments from the 10th Century with documentation tables. [ABSTRACT FROM AUTHOR]

In this study, a silicone resin solution was used as a supplementary binding agent, and two different techniques were employed to add varying amounts and layers of Al 2 O 3 fibers within the shell to improve the performance of investment casting shells. The Al 2 O 3 fiber-toughened shells were characterized using a combination of three-point bending and high-temperature self-loading deformation experiments. Additionally, the fracture morphology of samples and the fiber failure mode were demonstrated through SEM (Scanning Electron Microscope). Results showed that the added Al 2 O 3 fibers greatly improved the bending strength and the high-temperature self-loading deformation of the ceramic shells. After spraying the silicone resin solution, the green and sintered strengths of the shells reached 8.02 MPa and 9.60 MPa, respectively, when Al 2 O 3 fibers were added to the 3–6 layers of the shell. The high-temperature self-loading deformation reached a minimum of 0.44% when Al 2 O 3 fibers were added at 0.4 wt%. SEM analysis indicated that the incorporation of Al 2 O 3 fibers in the backing sand resulted in a disordered and non-directional distribution pattern, which could lead to the splitting of the ceramic matrix. In contrast, Al 2 O 3 fibers within each shell layer could uniformly disperse the external load and increase the fracture resistance of the substrate. Furthermore, the pyrolysis of the silicone resin led to the deposition of free carbon in the matrix pores, resulting in the spontaneous formation of SiC nanowires. These nanowires were observed to attach to the Al 2 O 3 fibers, which ultimately impeded the propagation of matrix cracks. [Display omitted] • The Al 2 O 3 fibers were incorporated into the ceramic shell using two different methods. • The SiC nanowires were formed within the matrix as an auxiliary reinforcing phase after the pyrolysis of the silicone resin. • The baked strength and self-loading deformation rate of the modified shell was increased by 5.42 MPa and 0.16, respectively. • The failure modes of Al 2 O 3 fibers in the ceramic matrix were self-fracture, pull-out, and debonding. [ABSTRACT FROM AUTHOR]

Simulated shallow seawater corrosion tests were conducted to explore the corrosion resistance of alumina fiberre-inforced aluminum matrix composites. The micromorphology, elemental composition, phase structure, and microhardness of ZL301 aluminum alloy-based and pure aluminum-based composites reinforced with different contents of copper-coated alumina fibers were studied using scanning electron microscope (SEM), energy-dispersive spectroscope (EDS), X-ray diffractometer (XRD), and Vickers hardness meter, respectively. The surface morphology and corrosion products of the ZL301 aluminum alloy-based composite containing 5% of copper-coated alumina fibers after being immersed in 5% NaCl solution for different time were characterized. The results showed that the corrosion resistance of pure aluminum surpassed that of ZL301 aluminum alloy. The addition of copper-coated alumina fibers weakened the corrosion resistance of the aluminum-based materials, and the corrosion resistance of the composites were gradually decreased with the increasing of fiber content. The corrosion process of copper-coated alumina fiber-reinforced ZL301 aluminum alloy matrix composite can be divided into three stages: a) adsorption of corrosive ions; b) formation of localized corrosion pits leading to the destruction of the surface oxide film; and c) corrosion of the matrix. [ABSTRACT FROM AUTHOR]

Constructing on soft clay entails engineering challenges, such as significant volumetric changes; hence, stabilizing such problematic soil is essential. Since using lime in stabilizing soil is not recommended in some regions (e.g., Manitoba, Canada) due to some environmental concerns, there is a pressing need to explore suitable alternatives. This study investigates the efficiency of stabilizing soft clay using nano-modified cementitious binders (cement, slag, and nano-silica), reinforced with a new class of fibers (basalt fiber pellets). The mechanical and durability properties of the mixtures have been tested in terms of California bearing ratio, unconsolidated–undrained triaxial stresses, and freezing–thawing resistance. Thermogravimetry and scanning electron microscope analyses were performed to interpret the bulk trends. The results showed significant improvement for soft clay specimens stabilized with the nano-modified cementitious binders and reinforced with the pellets. This demonstrates the potential of the proposed reinforced binders for field applications involving the stabilization of soft soils. [ABSTRACT FROM AUTHOR]

Polymers are the backbone of drug delivery. Electrospinning has greatly enriched the strategies that have been explored for developing novel drug delivery systems using polymers during the past two decades. In this study, four different kinds of polymers, i.e., the water-soluble polymer poly (vinyl alcohol) (PVA), the insoluble polymer poly(ε-caprolactone) (PCL), the insoluble polymer Eudragit RL100 (ERL100) and the pH-sensitive polymer Eudragit S100 (ES100) were successfully converted into types of tri-layer tri-polymer core–shell fibers through bi-fluid coaxial electrospinning. During the coaxial process, the model drug metronidazole (MTD) was loaded into the shell working fluid, which was an emulsion. The micro-formation mechanism of the tri-layer core–shell fibers from the coaxial emulsion electrospinning was proposed. Scanning electron microscope and transmission electron microscope evaluations verified the linear morphology of the resultant fibers and their obvious tri-layer multiple-chamber structures. X-ray diffraction and Fourier transform infrared spectroscopy measurements demonstrated that the drug MTD presented in the fibers in an amorphous state and was compatible with the three polymeric matrices. In vitro dissolution tests verified that the three kinds of polymer could act in a synergistic manner for a prolonged sustained-release profile of MTD in the gut. The drug controlled-release mechanisms were suggested in detail. The protocols reported here pioneer a new route for creating a tri-layer core–shell structure from both aqueous and organic solvents, and a new strategy for developing advanced drug delivery systems with sophisticated drug controlled-release profiles. [ABSTRACT FROM AUTHOR]

Alkali-activated slag (AAS) presents a promising alternative to ordinary Portland cement due to its cost effectiveness, environmental friendliness, and satisfactory durability characteristics. In this paper, cow dung waste was recycled as a renewable natural cellulose fiber, modified with alkali, and then added to AAS mortar. The physico-chemical characteristics of raw and modified cow dung fibers were determined through Fourier transform infrared (FTIR), X-ray diffraction (XRD), and Scanning electron microscope (SEM). Investigations were conducted on the dispersion of cow dung fibers in the AAS matrix, as well as the flowability, strength, and autogenous shrinkage of AAS mortar with varying cow dung fiber contents. The results indicated that modified fiber has higher crystallinity and surface roughness. The ultrasonic method showed superior effectiveness compared to pre-mixing and after-mixing methods. Compared with raw cow dung fibers, modified fibers led to an increase of 11.3% and 36.3% of the 28 d flexural strength and compressive strength of the AAS mortar, respectively. The modified cow dung fibers had a more significant inhibition on autogenous shrinkage, and the addition of 2 wt% cow dung fibers reduced the 7 d autogenous shrinkage of the AAS paste by 52.8% due to the "internal curing effect." This study provides an alternative value-added recycling option for cow dung fibers as a potential environmentally friendly and sustainable reinforcing raw material for cementitious materials, which can be used to develop low autogenous shrinkage green composites. [ABSTRACT FROM AUTHOR]

The main aim of this work is to comparatively reveal the effect of fibre type, length and content on compressive strength and microstructure of structural geopolymer concrete (GPC) produced under constant mixture and curing parameters in order to address the significant gap in present literature. Firstly, GPCs with different NaOH concentrations (i.e., 6, 9, 12 and 15 M) and activator solution/binder (a/b) ratios (i.e., 0.45 and 0.55) were produced in ambient curing condition, and optimum production parameters were determined based on the preliminary evaluations. Then, glass and polypropylene fibres in 6‐mm length (GS6 and PP6) and polyamide and polypropylene fibres in 12‐mm length (PY12 and PP12) were included in GPCs at ratio of 0.4%, 0.8% and 1.2% (by volume). Compressive strength, apparent porosity, bulk density, ultrasonic pulse velocity (UPV), X‐ray diffraction (XRD) and scanning electron microscope (SEM) analysis of GPC samples were carried out comparatively. The inclusion of GS6 fibre enhanced the compressive strength thanks to fibre surface being covered by geopolymer gel and the strong adhesion between GS fibre and geopolymer matrix. SEM images of fibre reinforced GPC (FRGPC) also confirmed the experimental findings, which were attributed to improvement in compressive strength. Regardless of the fibre type, the maximum compressive value strength was obtained from GPC specimens with 0.4% fibre and then decreased. Higher fibre inclusions led to poor compaction, workability issues and inhomogeneous fibre dispersions. A very good relation (R2 = 0.98) was acquired between UPV and compressive strength values of GPC/FRGPC samples. [ABSTRACT FROM AUTHOR]

Abundant research on geopolymer concrete in the last two decades has provided worldwide acceptability in conventional structural applications. The high-impact applications of geopolymers are mostly limited because they are quasi-brittle in nature and show moderate crack resistance; hence, they require suitable reinforcing materials such as fibers. This paper reports a study to assess the strength and durability properties of fly ash-based geopolymer concrete (FA-GPC) prepared with novel C-glass fibers. The binder mix was comprised of Fly Ash (FA), Lime (L), Silica Fume (SF) and was activated by sodium hydroxide (12 M) and sodium silicate solution, followed by curing under ambient conditions. Glass fibers were utilized in varying proportions (0.125, 0.25, 0.375, 0.5, 0.625, and 0.75%), by weight of the binder mix. It was found that the incorporation of 0.5% glass fiber significantly increased the compressive strength, split tensile strength, and flexural strength properties. From the durability perspective, the samples exhibited good resistance against seawater, MgSO4 solution, and H2SO4 when compared with the control mix. Further, the Scanning Electron Microscope (SEM) analysis was employed to explore the nature of the geopolymer–fiber matrix. It was revealed that excellent interfacial bonding existed between fiber and the geopolymer matrix. The results indicate that addition of C-glass fibers significantly improves the overall mechanical performance of FA-GPC. The research presented here establishes the advantages of using C-glass fibers-based geopolymer concrete, thus encouraging its broader utilization. [ABSTRACT FROM AUTHOR]

This article presents a self‐developed continuous fiber 3D printing device that incorporates a tilted printing axis. By positioning the print nozzle axis at an obtuse angle to the printing plane, the device effectively prevents the common issue of fiber damage during the 90° extrusion of continuous fibers. This improvement is substantiated through tensile strength experiments. Additionally, the pretreatment stage includes the twisting of continuous fibers to enhance friction along their length. This twisting process enables better retention of the matrix during impregnation, thereby improving impregnation performance. The cross‐section of the printed sample is observed by scanning electron microscope, and the microscopic effects of different process parameters on the continuous fiber structure are analyzed. Consequently, a link from process parameters to the mechanical properties of continuous fiber 3D printed specimens is established. This link serves as a foundation for predicting and optimizing the properties of continuous fiber‐reinforced materials. [ABSTRACT FROM AUTHOR]

The post-treatment of recycling the fine photocatalyst nanoparticles restricts their application. In this study, a new photocatalytic material was synthesized by immobilizing the N-doped TiO2 and graphene oxide (GO) composite on polypropylene (PP) (N–TiO2/GO/PP) fibre sheet, and characterized based on X-ray diffraction spectroscopy (XRD), Raman spectroscopy and Scanning Electron Microscope (SEM). The photocatalytic activity was evaluated using roxithromycin (ROX) as a typical antibiotic pollutant. XRD, Raman spectra and SEM images proved that N–TiO2/GO/PP fibre sheet was successfully synthesized. The photocatalytic degradation of 10 mg L−1 ROX can reach up to 90% and the degradation rate constant was 0.2299 h−1 in surface water with the application amount of TiO2/GO/PP fibre sheet of 24.6 cm × 2.7 cm and reaction time of 9 h under the irradiation of simulated sunlight. The application amount of TiO2/GO/PP fibre sheet, initial concentration of ROX and water matrix significantly affect the degradation of ROX. A low concentration of natural organic matter (NOM) slightly promoted the degradation of ROX, while a high concentration of NOM significantly inhibited the degradation of ROX. Alkaline condition (pH 8–9) is favourable for the photocatalytic degradation of ROX by TiO2/GO/PP fibre sheet. The photocatalytic reactivity of the TiO2/GO/PP fibre sheet showed no significant decrease after three runs. Two primary degradation products of ROX were identified and they showed lower ecotoxicity than ROX. The results demonstrate that the new synthesized TiO2/GO/PP fibre sheet shows promising application prospects in the treatment of antibiotics in wastewater and surface waters. [ABSTRACT FROM AUTHOR]

Fibroin, derived from cocoon, is a natural polymer used widely and increasingly in various fields. In recent years, the development of fluorescent fibroin has gained attention in the field of tissue engineering, because of its biocompatibility, oxygen and water vapor permeability, biodegradability, and ability to be tested non-invasively. In this work, silk fibroin and fluorescent silk fibroin fibers were fabricated via electrospinning, a simple process through which continuous submicron fibers can be produced. Degummed silk was extracted by dissolving in a calcium chloride solution. The fibroin powder was dissolved in formic acid to form 10, 12, and 14 wt.% solutions. Fluorescent fibroin solutions were achieved with the addition of fluoresceine sodium (FS) as a fluorescent dye. The fluorescent solutions were prepared at 10 wt.% fibroin with varying FS concentration at 0.1, 0.3, and 0.5 wt.%, and at 0.5 wt.% FS with varying fibroin concentration at 10, 12, and 14 wt.%. The fibroin solutions were fabricated into fibers via electrospinning using an applied voltage of 20 kV. The surface morphology of silk fibroin fibers and fluorescent fibroin fibers, observed by scanning electron microscope (SEM), showed long continuous fibers. The average fiber diameter, in sub-micron range, was found to increase with fibroin concentration. The fluorescence intensity observed by fluorescence spectrophotometer was found to increase with decreasing fluorescent dye concentration. The functional groups and chemical structure of silk fibroin fibers analyzed by infrared spectroscopy (IR) were not affected by the addition of the fluorescent dye. [ABSTRACT FROM AUTHOR]

In order to broaden the application area of seaweed fiber, a dynamic double network structure of inorganic nanoparticles (VSNP) was designed. VSNP was used as the physical crosslinker, ammonium persulfate (APS) as the initiator, acrylic acid (AA) as the monomer, polyethylene glycol (PEG) as the phase change functional modification, and calcium chloride (CaCl2) was used as the coagulation bath. By utilizing free radical polymerization and wet spinning techniques, a strong and tough phase change seaweed fiber with a dynamic double network structure (PEG/CA/PAA-VSNP) was successfully prepared. The structure and properties of PEG/CA/PAA-VSNP fibers were characterized using a FTIR spectrometer, an electronic single fiber strength meter, a differential scanning calorimeter (DSC), a scanning electron microscope (SEM), an X-ray diffractometer (XRD), a contact angle tester and a thermogravimetric analyzer (TG). It was found that the mechanical and phase change properties of PEG/CA/PAA-VSNP fibers were significantly higher than those of calcium alginate (CA) fibers: when the contents of PAA and VSNP were 15 wt%, and 7 wt%, respectively, and the mass ratio of SA to PEG was 1 : 4, the breaking strength and breaking elongation of the modified fiber reached 3.47 cN per dtex and 13.97%, which were 72.64% and 69.34% higher than those of the CA fibers, respectively. The enthalpy of melting and enthalpy of crystallization were 36.22 J g−1 and 35.19 J g−1, respectively. Compared with the CA fibers, the hydrophilicity and heat resistance of PEG/CA/PAA-VSNP fibers have also been improved. Therefore, this study is expected to achieve the application of seaweed fibers in more fields. [ABSTRACT FROM AUTHOR]

Cotton (Gossypium species) was used as textile fibre already in the early Indus culture, and since then it has been cultivated in Tropical and Subtropical regions around the whole planet. The species G. hirsutum is nowadays the dominant cotton crop with more than 90% of the world market, while G. barbadense, G. herbaceum and G. arboreum combined, the other cultivated species of Gossypium genus total a minor part of world's cotton production. Even in places where cotton was not cultivated, it could be an important trade item and income source for local textile centres, with the imported raw cotton lint being spun, woven and for some part exported from such sites around the globe. This all occurred far away from Finland, until changes brought by the development of long-distance trade and the Industrial Revolution. Based on archaeological finds, cotton as a textile material reached Finland relatively late, in the early Middle Ages. The article focuses on the problematic nature of identifying these cotton finds: whereas modern cotton fibres are easy to identify, the archaeological finds can at first sight be confused with bast or un-degummed silk fibres. This issue will be approached through reviewing recent Finnish cotton finds in heritage textiles. Additionally, the article examines whether the four cultivated cotton species could be differentiated using both classical and newly developed fibre identification methods, such as optical microscopy methods, a Scanning Electron Microscope (SEM), Fourier-transform infrared spectroscopy (FTIR) or Wide-Angle X-ray Scattering (WAXS). [ABSTRACT FROM AUTHOR]

Natural fibers derived from cellulose and ligno-celluloses materials have many advantages, such as being renewable, low density, inexhaustible, and cheap rather than synthetic fibers. Researchers and scientists are searching for a new fiber source that can be processed environmentally sustainable. The aim is to produce an organic and Eco-friendly product. The present investigation aims to extract and characterize ligno-cellulosic fiber from the seedpod of Wrightia tinctoria (WT) and Cebia pentandra (CP) plants. The extraction of WT fibers (WTFs) and CP fibers (CPFs) was carried out using the hand-stripping method. The structural and functional Characterization of WTFs and CPFs were determined using Scanning Electron Microscope (SEM), Fourier Transform Infrared (FT-IR) spectroscopy, Chemical analysis, X-ray diffraction studies (XRD), and the thermal behavior of fibers determined by using Thermo Gravimetric Analysis (TGA). The results indicated that WTFs composed of 75% cellulose, 14% lignin, and 0.55% wax content were, as the CPFs were composed of 38% cellulose, 15% lignin, and wax content of 2.34%. The SEM micrograph confirms that both fibers were hollow structures with thin cell walls and luminous because of the wax content presence on the surface of the fiber. The crystallinity percentage of WTFs and CPFs was calculated from XRD studies and is valued at 62% and 52%. Thermo gravimetric analysis revealed that WTFs and CPFs were thermally stable up to 460°C and 350°C. The above characterization results confirm that WTFs and CPFs have a wide scope in textile and polymer composite applications. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the improvement of selected mechanical properties of a resin-modified glass-ionomer cement (RMGIC) with a discontinuous short E glass fiber flowable resin composites (GFRRC) to be used in load-bearing areas of permanent teeth. Methods: Experimental materials were prepared using two different weight proportions, 7 wt% (1.75% E glass fibers) and 25 wt% (6.25% E glass fibers) of a GFRRC into an RMGIC matrix. Flexural strength was evaluated in 0- and 24-hour hydration periods, and fracture toughness was assessed after 24 hours. The internal microstructure of fractured samples was evaluated using a scanning electron microscope. Results: The addition of 25% of GFRRC was more effective in strengthening RMGIC than the introduction of only 7% GFRRC. Hydration periods did not show any significant statistical difference (P > 0.05). SEM micrographs of experimental materials' fractured surfaces revealed pull-out and fractured fibers; the presence of the matrix attached to fibers indicates great fiber-matrix adhesion. Within the limitations of the study, the results revealed that reinforcing RMGIC with discontinuous short E glass fiber flowable resin composites (GFRRC) improved significantly the flexural strength and modestly enhanced fracture toughness. [ABSTRACT FROM AUTHOR]

In this article, gray relational analysis (GRA) was carried out to study the influence of fiber length, fiber loading, and injection parameters on the mechanical, thermal, and morphological properties of the developed green composites. The green composite was developed by chemically modifying the pineapple leaf fiber (PLF). PLF was chemically treated with 1% Na2CO3 for a period of 6 h. The chemically modified PLF was chopped at a fiber length (L) of 2, 3, 4, 5, and 6 mm. The fiber loading (D) was also varied to 10, 20, and 30 wt% to study the effect of both fiber length and loading on the tensile and flexural properties of the PLF/PLA green composite developed through injection molding. GRA was employed to determine the optimal fiber length and fiber loading for achieving better tensile and flexural properties of PLF/PLA green composite. The injection parameters considered for producing the PLF/PLA green composite were (a) injection pressure (70, 90, and 110 bars), (b) injection speed (40, 50, and 60 mm/s), and (c) melting temperature (165, 175, and 185°C). The mechanical (tensile, flexural, compression, and shear) and thermal (TGA: thermogravimetric analysis and DTG: derivative thermogravimetric analysis) behavior of the developed PLF/PLA green composite was studied and analyzed. The morphology of the fractured specimens was also inspected using field‐emission scanning electron microscope (FESEM). [ABSTRACT FROM AUTHOR]

In the construction of an armor for ballistic protection, fibers are used in the form of a laminated composite bonded to the back of the frontal ceramic layer. The composite layer dissipates energy transmitted through the ceramic layer and controls the spall. To absorb energy locally and to spread it out fast, fibers in the composite layer must have high toughness and tensile wave speed as quantified by a primary performance index called normalizing velocity. The goal of this investigation is to increase the normalizing velocity of ultra‐high molecular weight (UHMWPE) fiber that is widely used in ballistic protection. The structure of UHMWPE is modified by hybridizing with nylon and reinforcing with carbon nanotubes. Fibers are extruded by melt‐spinning. The concentration of nylon and nanotubes is 18 and 2 wt%, respectively. After extrusion, fibers are strain‐hardened by cyclic loading to align UHMWPE molecules and nanotubes along the fiber axis. Tensile properties are determined to calculate normalizing velocity. Normalizing velocities up to 1270 m/s were obtained for the modified fiber which outperforms Spectra‐2000 and Dyneema‐SK75 by 44%–57%. Materials chemistry and structure of the fiber are investigated through differential scanning calorimetry (DSC), Raman Spectroscopy, and scanning electron microscope (SEM). It was observed that micro‐droplet formation by the nylon phase during hybridization promotes interface sliding of UHMWPE ligaments and elevates the fracture strain. Raman and SEM examination demonstrates that embedded nanotubes get aligned along the fiber axis due to strain hardening and co‐continuously deform with UHMWPE sharing the load. [ABSTRACT FROM AUTHOR]

In this study, we entirely replaced petroleum‐based bisphenol A (BPA) with unmodified kraft softwood lignin in epoxy resin formulation. Epoxidized lignin was prepared by reacting lignin with biobased epichlorohydrin (ECH) made from glycerol, and the formation of epoxide rings was confirmed by measuring the epoxy content of the epoxidized lignin using titration and Fourier‐transform infrared spectroscopy (FTIR). A fully biobased epoxy resin was then prepared by mixing the epoxidized lignin with a biobased curing agent derived from chew nutshell (from Cardolite Co.). Pre‐impregnated composite sheets were fabricated by impregnating unidirectional bamboo fibers with the developed water‐dispersion epoxy resin. The properties of the biobased composite samples were measured using a dynamic mechanical analyzer (DMA), scanning electron microscope (SEM), and a universal testing machine. The flexural strength of the lignin‐based epoxy composite was found to be 36% lower (14 MPa) compared to commercial epoxy (22 MPa). However, when bamboo fibers were added to the lignin‐based biocomposite (containing 25 wt.%), a higher flexural strength (116 MPa) was observed, representing an increase of 11% compared to the biocomposite made with EPON and bamboo fiber (104 MPa). Similarly, the addition of bamboo fibers to the lignin epoxy resulted in an increase in the flexural modulus by 1255% (from 0.42 to 5.69 GPa), while the flexural modulus of commercial epoxy was increased by only 736% (from 0.58 to 4.85 GPa). This was attributed to the higher compatibility of bamboo fiber with lignin, which is known to act as a natural glue in plants. [ABSTRACT FROM AUTHOR]

The use of engineered cementitious composite (ECC) is increasing owing to its high tensile strength and ductility; however, little attention has been paid to substitutes for its ingredients. Blast furnace slag instead of fly ash and polypropylene (PP) fibres instead of polyvinyl alcohol (PVA) fibres may be considered to be appropriate alternative substitutes. Therefore, the present study aimed to produce an ECC with a large proportion of slag and PP fibres that would achieve high strength and ductility characteristics and create controlled microcracking behaviour under tensile stresses (i.e. strain-hardening behaviour). The specimens made from ECC thus prepared were subjected to compressive, four-point bending, X-ray diffraction (XRD) and scanning electron microscope (SEM) tests. The results showed that a slag/cement ratio of 0.5 in ECC led to the highest compressive strength (55.6 MPa) and modulus of rupture (MOR) (7.0 MPa), while the corresponding energy absorption was fairly high. The results of XRD and SEM analyses indicated that applying the slag/cement ratio of 0.5 led to a homogenous cement matrix and produced the highest calcium-silicate-hydrate (C-S-H) in the ECC microstructure. Finally, to predict the load–deflection of specimens, a three-part model was proposed and verified with other available data. [ABSTRACT FROM AUTHOR]

With the aid of an electronic universal testing machine and a scanning electron microscope, uniaxial compression tests and microscopic examinations of cemented tailings backfill with mixed fibers were carried out in order to investigate the impact of mixing steel fiber (SF) and polypropylene fiber (PF) on the static mechanical properties and failure mode. The findings demonstrate that; the inclusion of hybrid fiber has a substantial impact on the failure mode of the backfill; the CTB is mostly damaged by single bevel shear, displaying an evident brittle failure;the SP-FRB is primarily damaged by relatively minor secondary cracks due to the bridging and crack-resisting action of internal fibers; and the specimen is fractured as a whole,demonstrating an obvious ductile deformation; The addition of hybrid fiber can increase the filler s uniaxial compressive strength,but there is a maximum amount that should be used. The stress-strain curves of both CTB and SP-FRB contain four stages: pore compaction, linear elastic deformation, plastic yield,and post-failure. The results of the microscopic tests indicate that the initial pore size and number inside the filler are significant factors in its failure. Steel fiber and polypropylene fiber can both maintain high integrity inside the filler and prevent crack expansion through adhesion with the matrix and their own fatigue fracture, respectively. [ABSTRACT FROM AUTHOR]

Global warming has led to a change in climatic conditions. Since 2006, drought has contributed to a reduction of food production and other agriculture-based products in many countries. The accumulation of greenhouse gases in the atmosphere has caused some changes in the composition of fruits and vegetables, making them less nutritious. To analyse this situation, a study was conducted on the effect of drought on the quality of fibres provided by the main fibre crops in Europe, namely flax (Linum usitatissimum). The experiment consisted of growing flax under controlled comparative conditions with designed different irrigation levels, such as 25%, 35% and 45% field soil moisture. Three varieties of flax were grown in 2019, 2020 and 2021 in the greenhouses of the Institute of Natural Fibres and Medicinal Plants in Poland. Fibre parameters, such as linear density, length and strength, were evaluated according to relevant standards. In addition, scanning electron microscope images of the cross-section and longitudinal view of the fibres were analysed. The results of the study indicated that deficiency of water during the flax growing season resulted in lowering of fibre linear density and tenacity. [ABSTRACT FROM AUTHOR]

Background: COVID-19 pandemic is not yet over, and it has been generating lots of plastic wastes that become a big concern. To catch the virus, for example, no matter via antigen or PCR test, swab is generally used for sampling. Unfortunately, the swab tip is commonly made of plastics, and thus it can be a potential source of microplastics. This study aims to propose and optimise several Raman imaging to identify the microplastic fibres released from different COVID-19 test swabs. Results: The results show that Raman imaging can effectively identify and visualise the microplastic fibres released from the swabs. In the meantime, on the surface of the fibres, additives such as titanium oxide particles are also captured for some brands of swabs. To increase the result certainty, scanning electron microscope (SEM) is first employed to get the morphology of the released microplastic fibres, along with Energy-dispersive X-ray spectroscopy (EDS) to confirm the presence of titanium element. Then, Raman imaging is advanced to identify and visualise the microplastics and titanium oxide particles, from different characteristic peaks in the scanning spectrum matrix. To further increase the imaging certainty, these images can be merged and cross-checked using algorithms, or the raw data from the scanning spectrum matrix can be analysed and decoded via chemometrics, such as principal component analysis (PCA). Beyond the advantages, the disadvantages of the confocal Raman imaging (affected by focal height) and algorithms (non-supervised calculation) are also discussed and intentionally corrected. In brief, the imaging analysis (particularly the combined SEM with Raman) is recommended to avoid the possible result bias that might be generated from the single spectrum analysis at a selective but random position. Conclusions: Overall, the results indicate that Raman imaging can be a useful tool to detect microplastics. The results also send us a strong warning that, if we worry about the potential microplastics contamination, we should be cautious to select the suitable COVID-19 testing kits. [ABSTRACT FROM AUTHOR]

Fabrication of highly aligned fibers by far-field electrospinning is a challenging task to accomplish. Multiple studies present advances in the alignment of electrospun fibers which involve modification of the conventional electrospinning setup with complex additions, multi-phased fabrication, and expensive components. This study presents a new collector design with an origami structure to produce highly-aligned far-field electrospun fibers. The origami collector mounts on the rotating drum and can be easily attached and removed for each round of fiber fabrication. This simple, effective, and inexpensive technique yields high-quality ultra-aligned fibers while the setup remains intact for other fabrication types. The electrospun poly(ɛ-caprolactone) (PCL) fibers were assessed by scanning electron microscope (SEM), fiber diameter distribution, water contact angle (WCA), Fast Fourier Transform analysis (FFT), surface plot profile, and pixel intensity plots. We thoroughly explored the impact of influential parameters, including polymer concentration, injection rate, collector rotation speed, distance from the collector to the tip, and needle gauge number on fibers' quality and alignment. Moreover, we employed machine learning algorithms to predict the outcomes and classify the high-quality fibers instead of low-quality productions. [ABSTRACT FROM AUTHOR]

The near stoichiometric SiC fiber has been reported to play significant roles in the application of aeroengine field. An in‐depth understanding on the degradation mechanism of the fiber during its corrosion in air and under a simulated aeroengine environment (PH2O:PO2:PAr = 14:8:78 kPa) will shine a light on the performance evaluations of the near stoichiometric SiC fiber‐based materials as well as the development of their potential applications. In this study, X‐ray diffraction, scanning electron microscope, and FIB‐TEM were utilized to analyze the mechanical properties and microstructure of the fiber. After oxidation in dry air and Ar–H2O–O2 for 1 h, respectively, the fiber strength retention rate has been found to decrease with the increased oxidation temperature. The raise in oxidation temperature also led to the increase of the thickness and the crystallization rate of the oxide scale. The most different oxidation behaviors of SiC being treated under the simulated environment than in air are the lower oxidation activation energy and the higher crystallization activation energy for cristobalite. Water vapor can promote the oxidation reaction and inhibit the crystallization of cristobalite in the oxide scale. Few significant differences have been observed otherwise in the oxidation process and oxidation chromatography crystallization mechanism of fibers being treated under different conditions. The increase of oxide layer thickness and the formation of cristobalite impair the structural integrity and compactness of the oxide scale and thus lead to the deterioration of the mechanical properties of SiC fibers. Therefore, it is proposed that oxidation resistance of SiC fiber can be improved by insulating the reaction between the oxidizing agents and the SiC fiber or by increasing the crystallization temperature of cristobalite in the oxidation process and reducing the crystallization rate. [ABSTRACT FROM AUTHOR]

The fibers of the deep-sea sponge Euplectella aspergillum exhibit exceptional mechanical properties due to their unique layered structure at a micrometer length scale. In the present study, we utilize a correlative approach comprising of in situ tensile testing inside a scanning electron microscope (SEM) and post-failure fractography to precisely understand mechanisms through which layered architecture of fibers fracture and improves damage tolerance in tensile loading condition. The real-time observation of fibers in the present study confirms for the first time that the failure starts from the surface of fibers and proceeds to the center through successive layers. The concentric layers surrounding the central core sacrifice themselves and protect the central core through various toughening mechanisms like crack deflection, crack arrest, interface debonding, and fiber pullout. Biological materials often exhibit multiscale hierarchical structures that can be incorporated into the design of next generation of engineering materials. The fibers of deep-sea sponge E. aspergillum possess core-shell like layered architecture. Our in situ study reveals astounding strategies by which this architecture delays the fracture of the fiber. The core-shell architecture of these fibers behaves like fiber-reinforced ceramic matrix composite, where the outer shells act as a matrix and the central core acts as a fiber. The outer shells take the environmental brunt and scarify themselves to protect the central core. The precise understanding of damage evolution presented here will help to design architected materials for load-bearing applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) is a piezoelectric polymer for the potential massive production of smart textiles, facing the difficulty of synergetic improving its fiber strength and softness. Strengthening of flexible PVDF fibers via drawing incurs the reduction of fiber softness. Here, inspired by the cotton fibers, this study aimed to construct a strong and soft PVDF fiber by regulating its cross-sectional shape and longitudinal convolution. Mechanism of increasing softness by longitudinal spiral twisting was conducted during the strengthening of PVDF fibers with favorable cross-sectional shapes. Then circular, flat and kidney shaped PVDF fibers were prepared to conduct drawing and twisting under different parameters. The influences of cross-sectional shapes and convolutions on PVDF fiber properties were examined using scanning electron microscope (SEM), X ray diffraction (XRD), universal stretch meter and AFM. Results indicated that all the fibers became strong but rigid with increased drawing ratios, mainly due to their corresponding attenuation to increase fiber inner crystallization and surface smoothness. In specialty, the circular fiber had a higher crystallization increase ratio (106.3%) than that of kidney (74.7%) and flat (73.1%) fibers. Surprisingly, all drawn fibers became flexible and further strengthened after tensile twisting within 400 T/m. Overall the optimum strong and flexible fibers were obtained by 400 T/m tensile twisting of the 2 times drawn flat PVDF fibers. [ABSTRACT FROM AUTHOR]

This article focuses on the mechanical property analysis of important models omitted in many scientific papers (thin-walled specimens) printed from innovative material—such as PLA + bronze composite—using fused deposition modelling technology. It discusses the printing process, the measurement of the specimen geometry, the static tensile strength tests and the microscopic examinations conducted with a scanning electron microscope. The findings of this study could be used as an input to further research into the accuracy of filament deposition and the modification of base materials with bronze powder and for the optimization of the machine design, e.g., with the use of cell structures. The experimental results indicated that the thin-walled models fabricated using FDM showed substantial differences in tensile strength, depending on the specimen's thickness and the printing orientation. It was shown that it was not possible to test thin-walled models located on the building platform along the Z axis due to the lack of sufficient adhesion between the layers. [ABSTRACT FROM AUTHOR]