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The SLS additive manufacturing industry enables the development of products for diverse applications with distinct properties due to its excellent surface finish and ability to create varied part geometries, but it consumes high-performance materials with high acquisition costs. An extensive quarrying of stone leads to the accumulation of mineral residues, posing environmental hazards by contaminating soil and water when disposed of in landfills. The primary objective of the study was to incorporate mineral waste into the SLS technique and investigate the influence of its addition, along with a silane-based chemical treatment, on the mechanical performance of polymer-mineral composites (PA12-slate). Additionally, the feasibility of producing a highly loaded printed prototype, employing 50 wt% of mineral waste, was examined. Samples of PA12, PA12 blended with 50 wt% slate waste, and slate waste treated with silane underwent fabrication via selective laser sintering (SLS) and subsequent mechanical characterization, including tensile, flexural, and compressive tests. Additionally, the samples underwent accelerated aging using a QUV weathering tester, followed by mechanical characterization. The geometric accuracy, stability, and processing feasibility of these formulations were evaluated through SLS-printed composite prototypes utilizing PA12_50Sla_Si. It was found that the addition of 50% of slate to the PA12 presented mechanical properties decreasing compared to the printed PA12 only. However, an increase was verified when using silane-induced mineral bonding. The incorporation of mineral agents and silane enhanced the resistance of PA12 to aging. However, after aging, both tensile and flexural strength decreased across all printed samples. Nonetheless, this study showcased the feasibility of producing complex PA12-slate waste specimens containing up to 50 wt% of mineral waste using the SLS printing technique. Therefore, SLS presents itself as a viable means of adding value to this mineral waste. [ABSTRACT FROM AUTHOR]

In fabric-cement composites, the limited impregnation of cementitious matrix products due to thick and twisted yarns leads to premature failure due to poor bonding strength. In addition, cellulosic textile reinforcements have many challenges about durability, appearance of voids at mortar-fiber interface, and rise of microcracks. Textile performances were evaluated in different conditions: coated with micro-silica powder, pretreated, and without any treatment. This study also assessed how textile weave structure and yarn geometry configuration affect the interactions of two different jute textiles (Close Weave Jute Fabric – CJF and Open Weave Jute Fabric - OJT) when used as reinforcement in mortar matrix. Textile characterization and composite analysis (by four-point bending tests, SEM/EDS, and physical tests) were conducted to assess the different textile reinforcements, the mechanical behavior of produced composites, and visual and chemical compounds analysis of the interfacial transition zone between textile and mortar matrix after silica coating. Micro silica powder coating was deemed necessary to address limited impregnation and to avoid telescope pull-off. Weave structure determined the difference between jute fabrics to reinforce mortar matrix, being only OJF (larger interstices in the weave structure) with micro silica coating allowed a better matrix interaction and stood out from the other textiles and achieved the best specific energy of all samples, (4.28 ± 0.91) kJ.m-2. Calcium and silicon inside the yarn interstices and textile-matrix interface indicate the formation of strong bonds by calcium-silicate-hydrate products. The silica coating treatment enhanced formation of strong bonds, which demonstrated future promise for natural fiber application. [ABSTRACT FROM AUTHOR]

Electroluminescence (EL) is an innovative technology in the lighting area. EL devices' main structure consists of a phosphor layer sandwiched between two electrodes. In this work, several alternating-current EL devices were developed by applying a set of sequential layers with combinations of in-house prepared inks and a commercially available ink as the phosphor layer. A flexible polyester textile substrate was functionalized with the inks by spray coating, after knife coating an interfacial layer directly on the surface. A thorough study was carried out on the phosphor layer composition to optimize the EL device performance, more precisely, illuminance intensity and illuminance homogeneity. The developed phosphor layer was composed of zinc sulfide doped with copper (between 30.0 and 38.1 wt%) and diluted by using a diluent at different concentrations (from 28.0 to 35.5 wt%). The best peak illuminance intensity of 61 lux was obtained when the phosphor ink presented a 35.4% ZnS:Cu ratio and was diluted with 33.0% diluent. This study aimed to determine the best formulation of the phosphor layer, which can be highly useful for further developments of EL devices, taking into account different applications in the market. [ABSTRACT FROM AUTHOR]

Cellulose has been intensively investigated for biomedical applications, because of its excellent properties, like biodegradability, biocompatibility, abundant availability of renewable resources and cost-effectiveness. Among all sources of cellulose, marine macroalgae or seaweeds, are acquiring tremendous attention, due to their high availability around the world. Moreover, the atypical proliferation of some exotic macroalgae species represents a serious problem to the ecosystems, since their accumulation threatens native oceanic species and resources worldwide. Several studies already reported the successfully extraction of cellulose and its derivatives from brown, green and red macroalgae. The extracted cellulose properties vary according to the type of algae, their maturity and the used extraction methods. This review will cover the main methods used to extract cellulose from algae, focusing on more sustainable ones, as well as its further processing into the various cellulose derivatives. Electrospun nanofibers have revealed great potential for biomedical applications, such as delivery of therapeutic agents, tissue engineering, wound dressings and enzyme immobilization. Pure cellulose presents some drawbacks, such as limited solubility in organic solvents and its inability to fuse due to inter and intra-molecular hydrogen bonding. To overcome these limitations, cellulose derivatives, which includes microcrystalline cellulose, cellulose nanocrystals, cellulose nanofibers, cellulose acetate and carboxymethyl cellulose, have been extensively studied to generate electrospun fibers. Therefore, this review aims to explore the marine seaweeds as a promising source of cellulose and its derivatives, the extraction methodologies of these compounds, as well as to demonstrate the potential of nanofibers developed by electrospinning with algae-based cellulose for biomedical applications. [ABSTRACT FROM AUTHOR]

Numerous elements, such as the composition and characteristics of carbon nanomaterials, the composition and characteristics of the matrix material, moisture levels, temperature, and loading circumstances, influence the piezoresistive behavior of self-sensing cementitious composites. While some past research has explored the impact of some of these factors on the performance of self-sensing cementitious composites, additional investigations need to be conducted to delve into how loading conditions affect the sensitivity of self-sensing cement-stabilized composites. Therefore, this study explores the influences of various loading conditions (i.e., location of loading regarding the location of recording electrodes, and loading level) on the electromechanical performance of self-sensing cement-stabilized sand. To this end, firstly, the evaluation of the percolation threshold based on 10% cement-stabilized sand specimens containing various multiwall carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) was performed. Then, 10% cement-stabilized sand containing 4% MWCNTs/GNPs was tested under various cyclic compressive stresses. The results suggested that the distance between the loading area and the electrode location used for recording the electrical resistance significantly impacted the sensitivity of cement-stabilized sand. Optimal sensitivity was achieved when the electrodes were positioned directly beneath the loading area. Moreover, the study showed that the stress sensitivity of self-sensing cement-stabilized sand increased proportionally with the stress level. An examination through scanning electron microscopy (SEM) demonstrated that the loading condition influences the bridging characteristics of carbon nanomaterials in cement-stabilized sand, leading to diverse electromechanical behaviors emerging based on the loading condition. This study underscores the importance of considering specific parameters when designing self-sensing cement-stabilized sand for application in practical field use. [ABSTRACT FROM AUTHOR]

Water security and industrial wastewater treatment are significant global concerns. One of the main issues with environmental contamination has been the discharge of dye wastewater from the textile and dye industries, contributing to an ever-growing problem with water pollution, poisoning water supplies, and harming the ecosystem. The traditional approach to wastewater treatment has been found to be inefficient, and biosorption techniques and mechanisms have been proven to be a successful replacement for conventional methods. Recent developments have led to the recognition of fibrous materials as an environmentally friendly option with broad application in several industries, including wastewater treatment. This review explores the potential of fibrous materials produced by the electrospinning technique as adsorbents for wastewater treatment, while at the same time, for the removal of adsorbates such as oil, dyes, heavy metals, and other substances, as reported in the literature. Textile wastewater filtering structures, produced by electrospinning, are summarized and the use of synthetic and natural polymers for this purpose is discussed. The limitations of electrospun textile wastewater filtering structures are also mentioned. Electrospun nanofibrous membranes appear to be a very promising route to filter textile wastewater and therefore contribute to water reuse and to reducing the contamination of water courses. [ABSTRACT FROM AUTHOR]

Premature failure and degradation of layers are the main problems for transportation infrastructure. Addressing these issues necessitates implementing structural health monitoring (SHM) for pavement construction layers. To this end, this research investigated the stress/strain and damage detection capabilities of a self-sensing cementitious composite developed for potential utilization in the construction of an intelligent subgrade layer. The prepared self-sensing cementitious composite consisted of 10% cement and hybrid conductive fillers, including multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) in sand. Initial findings reveal that the electrical resistivity of the composite is significantly affected by the concentration of MWCNTs/GNPs, with a minimum concentration of more than 0.5% needed to achieve a responsive cementitious composite. Moreover, the piezoresistive analysis indicates that an increase in the concentration of MWCNTs/GNPs and stress levels leads to an improvement in the stress/strain-sensing performance. When the self-sensing cementitious composite is subjected to equivalent stress levels, variations in the fractional changes in resistivity (FCR) exhibit an increasing trend with decreasing resilient modulus, stemming from a decrease in stiffness due to the increased concentration of MWCNTs/GNPs. Additionally, the electrochemical impedance spectroscopy (EIS) analysis demonstrates a contraction for the Nyquist plots under compressive ramp loading prior to failure, followed by the expansion of these curves post-failure. Scanning electron microscopy (SEM) images visually showcase the bridging effects of MWCNTs and the filling effects of GNPs within the composite structure. [ABSTRACT FROM AUTHOR]

Environmental factors, such as pressure and temperature, are known to contribute to the formation of ulcers that seriously affect bedridden individuals. Researchers have proposed several technologies to achieve the long-term monitoring of those parameters, usually relying on sensing mats, which poses difficulties in correlating the measurements with specific parts of the body. In this work, we aim to develop microsensors to be integrated into patient clothing. They should be highly flexible, thin with a small footprint, and can be achieved by taking advantage of the microfabrication on polyimide (PI) thin-film substrates (total device thicknesses below 30 µm). Both resistive and capacitance transduction mechanisms were explored, targeting operation ranges of 1 to 40 kPa and 24 to 42 °C. The sensors were integrated into textiles using silicone elastomers and electrical connections based on conductive silver yarn. The experimental characterization showed a nominal capacitance of 21 pF, a sensitivity of −8.44 fF/kPa for the pressure sensors, and a 0.0021 Ω/Ω°C sensitivity of the temperature sensor (with resistance of 29 kΩ at 22 °C). The proposed approach can potentially be implemented not only in wearable devices but also in many other applications for health monitoring or human–machine interfaces. [ABSTRACT FROM AUTHOR]

Auxetic laminates are part of a fascinating branch of materials denominated as auxetics, which display a NPR (Negative Poisson's Ratio), an uncommon property in the engineering world. Auxeticity is at the root of enhancements in shear and indentation resistance, fracture toughness and energy absorption, making the design of NPR a desirable feat in structural engineering. In composite laminates made of conventional, i.e. positive Poissons ratio, materials, auxeticity is a result of the combination between particular angular configurations and anisotropic materials. Such laminates can be used in a wide array of engineering applications, especially those which require high energy absorption capacity, including aerospace, personal defense and sports industries. This review focuses on particular property enhancements reported in the scientific world brought about by the design and application of IP (In-plane) and TTT (Through-the-thickness) NPR fibre-reinforced polymer laminates under QSI (Quasi-static indentation), LVI (Low-velocity impact) and fatigue solicitations. Furthermore, some insight is given on some possible future paths for further investigation of this topic. [ABSTRACT FROM AUTHOR]

The development of advanced facemasks stands out as a paramount priority in enhancing healthcare preparedness. In this work, different polypropylene non-woven fabrics (NWF) were characterised regarding their structural, physicochemical and comfort-related properties. The selected NWF for the intermediate layer was functionalised with zinc oxide nanoparticles (ZnO NPs) 0.3 and 1.2wt% using three different methods: electrospinning, dip-pad-dry and exhaustion. After the confirmation of ZnO NP content and distribution within the textile fibres by morphological and chemical analysis, the samples were evaluated regarding their antimicrobial properties. The functionalised fabrics obtained via dip-pad-dry unveiled the most promising data, with 0.017 ± 0.013wt% ZnO NPs being mostly located at the fibre's surface and capable of total eradication of Staphylococcus aureus and Escherichia coli colonies within the tested 24 h (ISO 22196 standard), as well as significantly contributing (**** p < 0.0001) to the growth inhibition of the bacteriophage MS2, a surrogate of the SARS-CoV-2 virus (ISO 18184 standard). A three-layered structure was assembled and thermoformed to obtain facemasks combining the previously chosen NWF, and its resulting antimicrobial capacity, filtration efficiency and breathability (NP EN ISO 149) were assessed. The developed three-layered and multiscaled fibrous structures with antimicrobial capacities hold immense potential as active individual protection facemasks. [ABSTRACT FROM AUTHOR]

This paper investigates the fragment performance of several composite panels for attaching to the inside walls of a building structure. These panels were developed using different types of fiber woven fabrics (W0, W90) combined with distinct layers orientations (angle-ply effect) of L0/0 and L0/15. Aramid, E-glass, and S-glass fiber fabrics impregnated with thermosetting epoxy resin, and a prepreg of Ultra High Molecular Weight Polyethylene (HB24) were employed. The panels are subjected to ballistic impact using different fragments under impact velocities in the range of 120 to 420 m/s. In order to measure the energy absorbed by the ballistic panels, the impact velocity and the residual velocity of the fragment were measured with laser chronographs placed before and after the laminated test specimens. The paper demonstrates quantitatively that the angle-ply laminates produced using L0/15 woven fabric orientation presented a higher impact energy absorption, promoting higher reductions on the fragment residual velocity compared to the L0/0 orientations. The laminates produced using UHMWPE fibers (HB24) presented better ballistic properties compared to the other fibers. Furthermore, it was noted that the energy dissipation rate is linearly correlated with the impact velocity and is independent of the fragment geometry. [ABSTRACT FROM AUTHOR]

Civil infrastructure monitoring with the aim of early damage detection and acquiring the data required for urban management not only prevents sudden infrastructure collapse and increases service life and sustainability but also facilitates the management of smart cities including smart transportation sectors. In this context, smart geosynthetics can act as vital arteries for extracting and transmitting information about the states of the strain, stress, damage, deformation, and temperature of the systems into which they are incorporated in addition to their traditional infrastructural roles. This paper reviews the wide range of technologies, manufacturing techniques and processes, materials, and methods that have been used to date to develop smart geosynthetics to provide rational arguments on the current trends and utilise the operational trends as a guide for predicting what can be focused on in future researches. The various multifunctional geosynthetic applications and future challenges, as well as operational solutions, are also discussed and propounded to pave the way for developing applicable smart geosynthetics. This critical review will provide insight into the development of new smart geosynthetics with the contribution to civil engineering and construction industries. [ABSTRACT FROM AUTHOR]

The high applicability of Bacterial Cellulose (BC) is often challenging due to its high production costs, which ultimately prevents its widespread use. Therefore, the present study aimed to investigate BC production using alternative feedstock to replace high-cost synthetic carbon and nitrogen sources and to evaluate the physical and structural properties of the produced BC membranes. BC was produced through a microbial consortium from kombucha, and the formulated alternative media sustained promising BC production, especially the association of apple wastes (at 10% (W/V)) with tea mixture, with a yield similar to BC produced on Hestrin–Schramm (HS) control media. Moreover, the BC samples produced in this alternative media also exhibited comparable properties to BC from HS media, with similar water-holding capacity and retention ability, thermal stability, mechanical behavior, and a crystallinity index of 87.61% and 88.08%, respectively. Thus, our findings substantiated that expensive substrates, such as glucose, peptone, and yeast extract, could be successfully replaced by apple wastes, black and green tea, for BC production while maintaining its remarkable physical and structural properties. Furthermore, besides the low-cost advantage, the bioconversion of apple waste also reduces the environmental burden caused by its disposal in landfills. [ABSTRACT FROM AUTHOR]

Pressure injuries (PIs) are a major public health problem and can be used as quality-of-care indicators. An incipient development in the field of medical devices takes the form of Smart Health Textiles, which can possess innovative properties such as thermoregulation, sensing, and antibacterial control. This protocol aims to describe the process for the development of a new type of smart clothing for individuals with reduced mobility and/or who are bedridden in order to prevent PIs. This paper's main purpose is to present the eight phases of the project, each consisting of tasks in specific phases: (i) product and process requirements and specifications; (ii and iii) study of the fibrous structure technology, textiles, and design; (iv and v) investigation of the sensor technology with respect to pressure, temperature, humidity, and bioactive properties; (vi and vii) production layout and adaptations in the manufacturing process; (viii) clinical trial. This project will introduce a new structural system and design for smart clothing to prevent PIs. New materials and architectures will be studied that provide better pressure relief, thermo-physiological control of the cutaneous microclimate, and personalisation of care. [ABSTRACT FROM AUTHOR]

Chemical protective clothing (CPC) has become mandatory when performing various tasks to ensure user protection and prevent chemicals from contacting the skin and causing severe injuries. In addition to protection, there is a need to develop a simple mechanism that can be attached to CPC and be capable of detecting and alerting the user to the presence of harmful chemical agents. In this study, a double-sensor strategy was investigated, using six different pH indicators stamped on cotton and polyester knits to detect acidic and alkaline substances, both liquid and gaseous. Functionalized knits underwent microscopic characterization, air permeability and contact angle evaluation. All samples exhibited hydrophobic behavior (contact angle > 90°) and air permeability values above 2400 L/min/cm2/bar, with the best condition demonstrating a contact angle of 123° and an air permeability of 2412.5 L/min/cm2/bar when the sensor methyl orange and bromocresol purple (MO:BP) was stamped on polyester. The performed tests proved the functionality of the sensors and showed a visible response of all knits when contacting with different chemicals (acids and bases). Polyester functionalized with MO:BP showed the greatest potential, due to its preeminent color change. Herein, the fiber coating process was optimized, enabling the industrial application of the sensors via a stamping method, an alternative to other time- and resource-consuming techniques. [ABSTRACT FROM AUTHOR]

Cancer remains one of the most challenging health problems worldwide, and localized therapeutic approaches based on micro/nanofibers have shown potential for its treatment. Micro/nanofibers offer several advantages as a drug delivery system, such as high surface area, tunable pore size, and sustained release properties, which can improve drug efficacy and reduce side effects. In addition, functionalization of these fibers with nanoparticles can enhance their targeting and therapeutic capabilities. Localized delivery of drugs and/or other therapeutic agents via micro/nanofibers can also help to overcome the limitations of systemic administration, such as poor bioavailability and off-target effects. Several studies have shown promising results in preclinical models of cancer, including inhibition of tumor growth and improved survival rates. However, more research is needed to overcome technical and regulatory challenges to bring these approaches to clinical use. Localized therapeutic approaches based on micro/nanofibers hold great promise for the future of cancer treatment, providing a targeted, effective, and minimally invasive alternative to traditional treatments. The main focus of this review is to explore the current treatments utilizing micro/nanofibers, as well as localized drug delivery systems that rely on fibrous structures to deliver and release drugs for the treatment of cancer in a specific area. [ABSTRACT FROM AUTHOR]

Fibrous materials are often used in the manufacturing of fire protection devices such as fire curtains. Their optimization and improved performance is still a topic of interest. The present work aims to develop and test a new combination of fibers arranged in various 2D and 3D patterns with coatings. For this purpose, basalt fibers were added into a glass fiber fabric, and wires of a shape memory material (SMM) were inserted into the fabric to create air pockets induced by temperature. In fire curtains, the base structure is a 2D basket pattern, and all combinations were tested with and without a waterborne polyurethane (WPU) coating with inorganic materials. Three different tests were selected to characterize the thermal behavior: fire resistance, ignitability, and smoke production. Fiberglass proved to be the best material to provide thermal resistance in fire curtains, with the outer surface temperature of the fabric below 650 °C at the end of the tests. The SMM wires provided good protection during the initial stages of the test, but a combination of excessive deformation and reduced strength of the fabric resulted in a sudden failure of the structure. Basalt fibers contribute to a reduction of smoke production. It was observed an improvement of up to 10% in the thermal capacity between 1MIX2 (glass fibers fabric with coating, MIX2) and the best commercial curtain evaluated, Commercial3 (glass and steel fibers fabric with coating). [ABSTRACT FROM AUTHOR]

Biological hazards can be defined as substances that endanger the life of any living organism, most notably humans, and are often referred to as biohazards. Along with the use of personal protective equipment (PPE), early detection of contact is essential for the correct management and resolution of a biological threat, as well as lower mortality rates of those exposed. Herein, Prussian blue (PB) was evaluated as a functional compound applied on polyester knits to act as an on-site sensor for bacteria detection. In order to study the best compound concentration for the intended application, polymeric solutions of 0.5, 1 and 2 g/L were developed. The three conditions tested displayed high abrasion resistance (>2000 cycles). The bacterial sensing capacity of the coated knits was assessed in liquid and solid medium, with the functionalised substrates exhibiting the capability of detecting both Gram-positive and Gram-negative bacteria and changing colours from blue to white. Evaluation of water repellence and chemical penetration resistance and repellence was also performed in polyester functionalised with PB 0.5 and 1 g/L. Both knits showed a hydrophobic behaviour and a capacity to resist to penetration of chemicals and level 3 repellence effect for both acid and base chemicals. [ABSTRACT FROM AUTHOR]

In this study, needleless electrospinning technology was used to obtain flexirubin (F)‐loaded polyvinyl alcohol (PVA)_kefiran (KF)/polycaprolactone (PCL) electrospun nanofibers. The SEM images of PVA_KF_ F and PCL_F nanofibers displayed beadless morphology with average diameters of 211.90 ± 96.08 and 1610.71 ± 996.68 nm, respectively. FTIR‐ATR analysis revealed increased intensity at specific wavelengths, after pigment incorporation. The high porosity exhibited by each layer and the mechanical properties of the double‐layered nanofibrous material remained unaffected after flexirubin‐type pigment incorporation. In addition, PVA_KF_F/PCL_F nanofibers showed antioxidant activity of 41.03 ± 0.29%, evaluated by the scavenging of the ABTS radical as well as the ability to reduce enzymatic browning of apple slices. Thus, we believe that the fabricated PVA_KF_F/PCL_F double‐layered material can be considered for application in active food packaging systems. [ABSTRACT FROM AUTHOR]

Due to the increase in the global terrorist threat, there has been a growing demand for materials that can more efficiently protect civil, industrial, and military structures against explosions. In this sense, two new commercial polyureas (A and B), that present high potential to be used as a protective coating on building facades against explosions, were compared in this work, through several tests. Chemical characterization with the Scanning Electron Microscope (SEM) of the surface of the polyureas revealed that the commercial polyurea A has a heterogeneous surface while the other polyurea has a more uniform and homogeneous surface, resulting in a more compact structure. The shock-wave attenuation ability of polyurea is believed to be controlled primarily by the hard domains. The TGA tests revealed that polyurea B has more hard segments than polyurea A in its composition. The mechanical tests performed showed that polyurea B has significantly better tensile properties-almost 3000% of maximum deformation capacity compared with approximately 115% of polyurea A. Thus, it was concluded that polyurea B has more potential to be used as a coating in building blast protection due to its exceptional elongation characteristics, a critical parameter to absorb the high frequency and intensity of blasts. [ABSTRACT FROM AUTHOR]

The development of materials with hydrophobic properties has been widely explored in areas such as textiles, healthcare, sports, and personal protective equipment. Hydrophobic properties that arise from nanoparticles (nPs) directly promote other valuable properties, including self-cleaning capabilities, decreased bacterial growth, and increased comfort. In this study, biodegradable poly(ε-caprolactone) (PCL) nanofibers were functionalized by the incorporation of titanium dioxide (TiO2) nPs to develop water-repellent materials. The membranes were produced through electrospinning, and variables such as the polymer concentration, nP concentration, and needle diameter were optimized to achieve PCL/TiO2 composite fibers with water-repellent capabilities. The nanofibers were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, and the water contact angle (WCA). In general, it was observed that the nanofibers presented higher roughness values when TiO2 nPs were present and that this result promoted higher WCA values. The highest WCA value (156°) was obtained for the nanofiber mat produced with 20% weight-to-volume (w/v) PCL and 0.6% (w/v) TiO2. [ABSTRACT FROM AUTHOR]

Although the force/pressure applied onto a textile substrate through a uniaxial compression is constant and independent of the yarn direction, it should be noted that such mechanical action causes a geometric change in the substrate, which can be identified by the reduction in its lateral thickness. Therefore, the objective of this study was to investigate the influence of the fabric orientation on both knitted and woven pressure sensors, in order to generate knowledge for a better design process during textile piezoresistive sensor development. For this purpose, these distinct textile structures were doped with different concentrations of graphene nanoplatelets (GNPs), using the screen-printing technique. The chemical and physical properties of these screen-printed fabrics were analysed using Field Emission Scanning Electron Microscopy, Ground State Diffuse Reflectance and Raman Spectroscopy. Samples were subjected to tests determining linear electrical surface resistance and piezoresistive behaviour. In the results, a higher presence of conductive material was found in woven structures. For the doped samples, the electrical resistance varied between 105 Ω and 101 Ω, for the GNPs' percentage increase. The lowest resistance value was observed for the woven fabric with 15% GNPs (3.67 ± 8.17 × 101 Ω). The samples showed different electrical behaviour according to the fabric orientation. Overall, greater sensitivity in the longitudinal direction and a lower coefficient of variation CV% of the measurement was identified in the transversal direction, coursewise for knitted and weftwise for woven fabrics. The woven fabric doped with 5% GNPs assembled in the weftwise direction was shown to be the most indicated for a piezoresistive sensor, due to its most uniform response and most accurate measure of mechanical stress. [ABSTRACT FROM AUTHOR]

Core–shell nanoparticles (NPs) based on metal oxides, namely magnesium oxide (MgO) and silica (SiO2), are a fantastic alternative for natural fibers' functionalization. In this work, flax fibers were functionalized with MgO and MgO–SiO2 core–shell NPs to achieve multifunctionality. The flax fabrics were functionalized with both NPs by a simple in-situ method. Parallelly, the synthesis of the isolated NPs was performed for comparison purposes. The developed samples were characterized, confirming the successful synthesis of the core–shell NPs and their incorporation onto the fabrics. The wash durability tests confirmed the beneficial effect of the SiO2 shell on the NPs' anchorage. Ultraviolet (UV) protection capability (UV protection factor (UPF) of 50 +) and hydrophobicity (water contact angle (WCA) of 123.0°) were achieved, together with antibacterial activity and the degradation of methylene blue (MB) capability. Overall, this work presents an innovative method for the synthesis of MgO–SiO2 core–shell NPs and their incorporation onto flax fabrics. [ABSTRACT FROM AUTHOR]

Smart textiles have become a promising area of research for heating applications. Coatings with nanomaterials allow the introduction of different functionalities, enabling doped textiles to be used in sensing and heating applications. These coatings were made on a piece of woven cotton fabric through screen printing, with a different number of layers. To prepare the paste, nanomaterials such as graphene nanoplatelets (GNPs) and multiwall carbon nanotubes (CNTs) were added to a polyurethane-based polymeric resin, in various concentrations. The electrical conductivity of the obtained samples was measured and the heat-dissipating capabilities assessed. The results showed that coatings have induced electrical conductivity and heating capabilities. The highest electrical conductivity of (9.39 ± 1.28 × 10−1 S/m) and (9.02 ± 6.62 × 10−2 S/m) was observed for 12% (w/v) GNPs and 5% (w/v) (CNTs + GNPs), respectively. The sample with 5% (w/v) (CNTs + GNPs) and 12% (w/v) GNPs exhibited a Joule effect when a voltage of 12 V was applied for 5 min, and a maximum temperature of 42.7 °C and 40.4 °C were achieved, respectively. It can be concluded that higher concentrations of GNPs can be replaced by adding CNTs, still achieving nearly the same performance. These coated textiles can potentially find applications in the area of heating, sensing, and biomedical applications. [ABSTRACT FROM AUTHOR]

An extensive experimental study was conducted to investigate the co-effects of surface area and distance between electrodes as well as filler scales on the percolation threshold of piezoresistive cement-stabilised sand. In this route, the electrical resistivity of numerous specimens of different sizes and composed of different content of carbon-based conductive fillers was measured, including carbon nanotubes (CNTs), graphene nanoplatelets (GNPs), and carbon fibres (CFs) with different aspect ratios. In addition, the numerical relations between the electrical percolation threshold and matrix dimensions were expressed for different conductive fillers. Furthermore, the electrical percolation threshold of two large-scale specimens with different shapes (a 10 × 10 × 85 cm3 beam, and a 15 cm size cube) were predicted through numerical relations, and their piezoresistivity performances were investigated under compression cyclic loading (cube) and flexural cyclic loading (beam). The mechanical properties of the specimens were also evaluated. The results showed that the changes in the length, width, and thickness of the matrix surrounded between electrodes had a significant effect on the electrical percolation threshold. However, the effects of length changes on the percolation threshold were greater than the width and thickness changes. Generally, increasing the aspect ratio of the conductive fillers caused a reduction in the electrical percolation threshold of the cementitious geocomposite. The appropriate piezoresistivity response of the large-scale specimens composed of filler content equal to their percolation threshold (obtained by the numerical relation presented in this study) showed the adequacy of the results in terms of threshold dosage prediction and self-sensing geocomposite design. The results of this study addressed a crucial factor for the design of self-sensing composites and pave the way for the development of field-applicable, smart, cementitious geocomposite. [ABSTRACT FROM AUTHOR]

Low-velocity impact can cause serious damage to the person or structure that is hit. The development of barriers that can absorb the energy of the impact and, therefore, protect the other side of the impact is the ideal solution for the pointed situation. Auxetic materials and shear thickening fluids are two types of technologies that have great capabilities to absorb high levels of energy when an impact happens. Accordingly, within this study, the combination of auxetic knits with shear thickening fluids by the pad-dry-cure process was investigated. It was observed that, by applying knits with auxetic patterns produced with denser materials and combined with the shear thickening fluids, high performance in terms of absorbed energy from puncture impact is obtained. The increment rates obtained are higher than 100% when comparing the structures with and without shear thickening fluids. [ABSTRACT FROM AUTHOR]

In this study, lignocellulosic fibers from Agave salmiana —an important socio-economical species endemic to Mexico— were used to reinforce thermoplastic maize starch (TPS). Fibers from young raw leaves (YRL) and old roasted leaves (ORL) were obtained according to the traditional methods used by small producers. The formulations of biocomposites were obtained varying the content of both types of fiber and processed by extrusion and injection molding. Morphological, structural, mechanical, thermal, and thermomechanical properties of biocomposites were evaluated. To use the hydrophilicity of these materials as an advantage in unexplored applications, biocomposites behavior under degradative tests such as accelerated aging and salt water immersion was evaluated. The processes of heating the old leaves partially removed the lignin and hemicellulose layer from the fibers, which led to a better interaction fiber-matrix, as confirmed by FESEM, ATR-FTIR, and TGA. Biocomposites with 30 wt% of YRL fiber reported the highest values of tensile strength and Young's modulus when compared to ORL biocomposites and with TPS. Accelerated aging exposure affected mainly the thermomechanical properties of TPS and confirmed the reinforcing effect of the fibers due to the thermal and mechanical stability they provided to the matrix, especially when 20 wt% of fiber was added. This was also observed when biocomposites were immersed in salt water solution. Using Agave salmiana fiber obtained from different leaf ages by traditional methods in the production of biocomposites promotes the complete harnessing of this species and represents a possibility to small producers in Mexico to introduce circular economy in their communities. [ABSTRACT FROM AUTHOR]

Due to the prevalence of the COVID-19 pandemic, the demand for disposable facemasks has become a global issue. Unfortunately, the use of these products has negative effects on the environment, and therefore, the use of biodegradable materials is a powerful strategy to overcome this challenge. Aligned with this concept, in this work, biodegradable facemasks were developed using poly(ε-caprolactone) (PCL) polymer and cotton natural fibers. The filter layer was produced using an electrospinning technique, since electrospun membranes present remarkable characteristics for air filtration. The electrospun membranes were functionalized with different nanoparticles (NPs), including silver (Ag), titanium dioxide (TiO2) and magnesium oxide (MgO), in order to include new properties, namely antibacterial effect. The developed membranes were characterized by FESEM, EDS, ATR-FTIR, GSDR and TGA, which confirmed the successful impregnation of NPs onto PCL membranes. The antibacterial effect and filtration efficiency were assessed, with the PCL/MgO NPs membrane presenting better results, showing inhibition zone diameters of 25.3 and 13.5 mm against Gram-positive and Gram-negative bacteria, respectively, and filtration efficiency of 99.4%. Three facemask prototypes were developed, and their filtration efficiency, air permeability and thermal comfort were evaluated. Overall, this study demonstrates the potential of PCL/NPs electrospun membranes to act as an active and biodegradable filter layer in facemasks. [ABSTRACT FROM AUTHOR]

Composite wound dressings which combine the suitable properties of distinct materials into one dressing are currently being explored, in combination with different types of bioactive compounds, to enhance the healing process and avoid skin infections. In the present work, poly(vinyl alcohol) and chitosan nanofibers containing Agrimonia eupatoria L. were fabricated using a needleless electrospinning method (through Nanospider technology) and deposited on top of a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cotton textile dressing. The negatively charged carboxyl groups on the cotton fibers interacted with the positively charged amino groups of chitosan, which was previously blended with poly(vinyl alcohol) and Agrimonia eupatoria L. to produce the nanofiber layer. The properties of the produced composite materials were analyzed to determine the dressing's potential for antimicrobial wound dressing applications. [ABSTRACT FROM AUTHOR]

Pigments from natural sources, such as bacterial pigments, have gained increased attention in recent years due to their biodegradability, non-toxicity, and noncarcinogenicity. The intention to replace synthetic and oil-derived compounds is not restricted to synthetic dyes; other applications include the replacement of oilderived polymers for more environmentally friendly options, such as biopolymers. In this work, the functionalization of a bacterial cellulose (BC) biopolymer with bacterial pigments was explored using a full factorial design methodology to evaluate the best functionalization conditions to produce colored BC. From the factors and interactions evaluated, it was possible to conclude that the variable duration of the functionalization procedure could be reduced to a low level without significantly affecting the functionalization of the BC samples with bacterial pigments. Moreover, BC is a product with high industrial applicability, versatility, and sustainability. Hence, the multifunctional colored BC can be applied in the packaging, paper, and textile industries, among others. [ABSTRACT FROM AUTHOR]

This study is a systematic attempt to develop a self-sensing fiber-reinforced cemented sand (CS) with high physical, mechanical, durability, and piezoresistivity performances. In this route, different concentrations of Dyneema, glass, and polypropylene (PP) fibers were incorporated into CS containing 0.17% hybrid carbon nanotubes and graphene nanoplatelets. The specimens were fabricated using the standard Proctor compaction method and tested at the optimum water content. The mechanical, microstructural, and durability performances of the specimens were evaluated through various types of tests. Further, the piezoresistivity of the specimens was evaluated under compression cyclic loads using the four probes method. The incorporation of 1.0% glass and Dyneema fiber as the optimum percent increased the unconfined compression strength (UCS) (29% and 82%, respectively) and the maximum dry density of the CS; however, reinforcing of the specimens with PP fiber at a concentration in the range of 0.5%–1.5% generally reduced the UCS of the specimens. The pullout test results exhibited a considerable interfacial performance for the Dyneema fiber. The CS reinforced with 1.0% Dyneema and glass fiber demonstrated a lower weight loss after 12 wetting and drying cycles compared to other specimens. The maximum gauge factors were also achieved for Dyneema fiber-reinforced CS. The outcomes of this study, balanced with sustainable issues, contribute to the development of the new era of smart structures, with applications to roller-compacted-concrete dams, rammed earth, and particularly in structural layers in transportation infrastructure. [ABSTRACT FROM AUTHOR]

The objective of this study is to analyze the impact behavior on the basis of energy approach of weft knitted structures, namely a jersey composite and an auxetic composite using high performance yarns. Weft knitted fabrics were produced with the same structural and machine parameters, using 100% para-aramid and hybrid (47% para-aramid and 53% polyamide) structure. Composite fabrication was achieved through hand lay-up using epoxy resin. Negative Poisson ratio of the reinforcing auxetic fabric was transferred from the fabric to the composite developed. Results obtained by drop weight dart impact test show that the impact experiment with different impact loads confirmed the auxetic composites, regardless de material composition, have an increase in the total energy absorption compared to jersey reinforced composite, approximately 2.5 and 4 times more for para-aramid and hybrid composite, respectively. Auxetic composites developed within this work present great potential for applications in different areas, mainly where energy absorption is a key factor to be considered, such as in protection, sports among others. [ABSTRACT FROM AUTHOR]

This paper reports new hierarchical cementitious composites developed using microcrystalline cellulose (MCC), sisal fibers and cetyltrimethylammonium bromide (CTAB) as the dispersing agent. MCC was dispersed in water without and with CTAB at different concentrations using ultrasonication and the optimum CTAB concentration for achieving homogeneous and stable MCC suspensions was found to be 40%. Hierarchical composites were fabricated using MCC (0.1–1.5 wt% of cement), sisal fibers (20 mm, 0.25% and 0.50 wt% of cement), 40% CTAB and tri-butyl phosphate as the defoaming agent. Mechanical strengths of composites improved significantly at 0.1 wt% MCC, which along with 0.5% sisal fibers improved compressive and flexural strengths by ~ 24% and ~ 18%, respectively. The hybrid reinforcement exhibited a synergistic effect on the fracture behavior of composites improving the fracture energy up to 40%. Hierarchical composites also showed improved fiber-matrix bonding, lower porosity and water absorption, superior hydration, carbonation resistance and durability up to 90 ageing cycles. [ABSTRACT FROM AUTHOR]

Over the years, the development of adaptable monitoring systems to be integrated into soldiers' body gear, making them as comfortable and lightweight as possible (avoiding the use of rigid electronics), has become essential. Electrospun microfibers are a great material for this application due to their excellent properties, especially their flexibility and lightness. Their functionalization with graphene nanoplatelets (GNPs) makes them a fantastic alternative for the development of innovative conductive materials. In this work, electrospun membranes based on polycaprolactone (PCL) were impregnated with different GNPs concentrations in order to create an electrically conductive surface with piezoresistive behavior. All the samples were properly characterized, demonstrating the homogeneous distribution and the GNPs' adsorption onto the membrane's surfaces. Additionally, the electrical performance of the developed systems was studied, including the electrical conductivity, piezoresistive behavior, and Gauge Factor (GF). A maximum electrical conductivity value of 0.079 S/m was obtained for the 2%GNPs-PCL sample. The developed piezoresistive sensor showed high sensitivity to external pressures and excellent durability to repetitive pressing. The best value of GF (3.20) was obtained for the membranes with 0.5% of GNPs. Hence, this work presents the development of a flexible piezoresistive sensor, based on electrospun PCL microfibers and GNPs, utilizing simple methods. [ABSTRACT FROM AUTHOR]

The removal of agriculture residual plastic films is nowadays a big concern for all environmentalists. Several ecological alternatives were developed for more sustainable products and cleaner production. In this work, the effect of three months of exposure under accelerated weathering conditions (ultraviolet light, moisture, and heat) on the properties of two textile waste nonwovens as a sustainable alternative to plastic mulching films was investigated. Results showed that thermostability and mechanical properties of the clothing textile waste felt and cotton waste nonwoven decreased after accelerated weathering. The chemical variation of cotton waste nonwoven and textile waste felt and the degradation rate of natural and synthetic fibers due to the photolysis and hydrolysis caused by accelerated weathering conditions were studied following the Fourier transform infrared spectroscopy and the fibrous composition variation of the blended textile waste felt structure during the study. [ABSTRACT FROM AUTHOR]

Fibrous based materials with exceptional functionalities have become a target of interest for researchers worldwide. One promising strategy for the development of active fibrous structures with improved functions is their functionalization with nanoparticles (NPs). In this work, jute fabrics were functionalized with calcium oxide (CaO) and silica (SiO2) NPs in order to obtain fibrous structures with several properties including, hydrophobicity, UV protection, antibacterial activity and the degradation of dyes ability. CaO and SiO2 NPs were synthesized via a simple in situ method, using sodium hydroxide (NaOH) as the reducing agent and water as solvent. Parallelly, the in situ synthesis of the CaO NPs was also tested. The final systems were fully characterized using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy, Ground-State Diffuse Reflectance and Field Emission Scanning Electron Microscopy and Energy Dispersive Spectroscopy. All these techniques confirmed the successful synthesis of the NPs as well as their well distributed presence onto the fabrics. The samples exhibited very good contact angle values, reaching 143.7° for the fabrics functionalized with CaO and SiO2 NPs and great values of ultraviolet (UV) protection factors (UPF), reaching 50+ for the functionalized fabrics. The developed systems also exhibited antibacterial activity against Staphylococcus aureus and Escherichia coli and photocatalytic activity for the degradation of methylene blue. The wash durability of the nanocoating was also evaluated, confirming that the SiO2 improved the NPs' anchorage onto the fabrics. Overall, this work presents for the first time, the development of jute fabrics with CaO–SiO2 NPs with several functionalities. [ABSTRACT FROM AUTHOR]

This paper reports a study undertaken to achieve a compatible and affordable technique for the high-quality dispersion of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) in an aqueous suspension to be used in multifunctional cementitious composites. In this research work, two noncovalent surfactants with different dispersion mechanisms (Pluronic F-127 (nonionic) and sodium dodecylbenzene sulfonate (SDBS) (ionic)) were used. We evaluated the influences of various factors on the dispersion quality, such as the surfactant concentration, sonication time, and temperature using UV-visible spectroscopy, optical microscopic image analysis, zeta potentials, and particle size measurement. The effect of tributyl phosphate (TBP) used as an antifoam agent was also evaluated. The optimum suspensions of each surfactant were used to produce cementitious composites, and their mechanical, microstructural, electrical, and thermal behaviors were assessed and analyzed. The best dispersed CNT+GNP aqueous suspensions using Pluronic and SDBS were obtained for concentrations of 10% and 5%, respectively, with 3 hours of sonication, at 40°C, with TBP used for both surfactants. The results also demonstrate that cementitious composites reinforced with CNT+GNP/Pluronic showed better mechanical performance and microstructural characteristics due to the higher quality of the dispersion and the increasing hydration rate. Composites prepared with an SDBS suspension demonstrated lower electrical and thermal conductivities compared to those of the Pluronic suspension due to changes in the intrinsic properties of CNTs and GNPs by the SDBS dispersion mechanism. [ABSTRACT FROM AUTHOR]

In this research, composites based on thermoplastic olefin (TPO) elastomers reinforced with natural fibers were developed, having had very interesting results, aiming toward an application in the automotive industry, for manufacturing car interior components. For the first time, sisal and coir fibers were used as reinforcement of TPO composites. The best‐performing samples have had a successfully reduced maximum elongation and improved both maximum stress and Young's modulus values. Different compositions were studied regarding several parameters: type of fiber (coir or sisal treated and nontreated), coupling agent presence (maleic anhydride grafted polypropylene [MAPP]) and fiber content. Overall, the presence of fibers has had a clear positive impact on the composites' mechanical properties, enhanced by the presence of MAPP, mostly when using 4% (w/w) of fiber content. The fibers' surface treatment was especially important in this work, enabling the evaluation of the fibers' alkali treatment's influence in the final mechanical properties of the composites. The treatment successfully removed some of the most hydrophobic constituents of the natural fibers, like lignin, improving the possibility of a better adhesion of the fibers to the matrix. Finally, the mechanical properties of the composites were evaluated, and it was concluded that the alkali pretreatment had a very positive effect on several of them, aided by the presence of MAPP. POLYM. COMPOS., 40:3472–3481, 2019. © 2019 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the thermo-physiological comfort properties of surgical cotton gauze coated with chitosan (CH) and its effectiveness for the prevention of bacterial colonization. Gauze was coated with CH at mass fractions of 0.50, 0.25, 0.125, 0.10, 0.063 wt% and the friction, flexibility, thermal, moisture management and mechanical properties were evaluated. The best performing gauze in terms of comfort (0.125 wt%) was further evaluated for its ability to inhibit the growth of microorganisms such as bacteria and yeast. Results indicate that the functionalized medical gauze could induce low friction on the wound bed allowing a good degree of moisture and high absorption capacity of wound exudates. Moreover, it shows antimicrobial properties against medical-relevant pathogens. This biofunctional medical gauze demonstrates to deliver an efficient antimicrobial coating and promote the best conditions for maintenance of the wound microenvironment. [ABSTRACT FROM AUTHOR]

Eight functional single jersey plain knitted fabrics have been developed in order to assess a quantitative analysis of various comfort-related properties in terms of thermal control, air and water vapor permeability, wickability, coefficient of kinetic friction and antimicrobial efficiency, using eight different commercially available functional yarns: Polyester Craque® and viscose Craque® conventional yarns as controls; Finecool® and Coolmax® polyester yarns for moisture management and quick drying; Holofiber® polyester yarns containing an optical responsive material that the producer claims to improve body oxygenation; Airclo® polyester hollow yarns for efficient control of body temperature; and, finally, polyester Trevira® and viscose Seacell® for antimicrobial activity. According to the results, Coolmax® for moisture management, Airclo® for thermal control and Seacell® for antimicrobial activity present the best performances as technical textiles for sportswear for the respective specific functional property. [ABSTRACT FROM AUTHOR]

This paper provides new insights regarding jute fibers functionalization with silver nanoparticles (Ag NPs) with improved conductivity values and highlights the sustainability of the processes involved. These NPs were applied onto jute fabrics by two different sustainable methods: ultraviolet (UV) photoreduction and by using polyethylene glycol (PEG) as a reducing agent and stabilizer. Field Emission Scanning Electron Microscopy (FESEM) images demonstrated that the Ag NPs were incorporated on the jute fibers surface by the two different approaches, with sizes ranging from 70 to 100 nm. Diffuse reflectance spectra revealed the plasmon absorption band, corresponding to the formation of metallic Ag NPs, in all samples under study. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) was used to characterize the obtained samples, demonstrating NPs adsorption to the surface of the fibers. The resistivity value obtained by the two-point probe method of the jute fabric without functionalization is about 1.5 × 107 WΩm, whereas, after NPs functionalization, it decreased almost 15,000 times, reaching a value of 1.0 × 103 WΩm. Further research work is being undertaken for improving these values, however, 1000 WΩm of resistivity (conductivity = 0.001 S/m) is already a very reasonable value when compared with those obtained with other developed systems based on natural fibers. In summary, this work shows that the use of very simple methodologies enabled the functionalization of jute fibers with reasonable values of conductivity. This achievement has a huge potential for use in smart textile composites. [ABSTRACT FROM AUTHOR]

This article presents innovative work undertaken to evaluate the auxetic composite materials developed using weft-knitted fabrics with negative Poisson’s ratio (NPR) produced from high-tenacity filaments of para-aramid (p-AR) and polyamide. The aim of this study is to develop polymeric composite materials reinforced with auxetic knitted fabrics and to evaluate the degree of transference of the auxetic behavior from the fibrous reinforcement to the composite produced. The results show that the NPR values remained in the composites. Regardless of the type of resin used, either epoxy or polyester, the highest values were obtained for samples produced with p-AR auxetic knitted fabrics. The NPR composites developed within this work present great potential for applications in industrial areas, including personal protection products, such as bulletproof vests, helmets, knee, and elbow protectors, and in all other areas where energy absorption is a key factor to be considered. [ABSTRACT FROM AUTHOR]

Self-sensing composites are becoming highly attractive for civil engineering applications to improve the safety and performance of structures. These smart composites show a detectable change in their electrical resistivity with applied stress or strain and this unique characteristic make them useful for health monitoring of structures. Till date, different forms of carbon composites, i.e. short fibre, continuous fibre, particles, nano fibres, nanotubes, etc. have been utilized for this purpose. In this context, the present paper reports an overview of different self-sensing composite systems used for the health monitoring of civil engineering structures. [ABSTRACT FROM AUTHOR]