Polymer Fibers Research Articles

Cell-Material Interplay in Focal Adhesion Points.

The complex interplay between cells and materials is a key focus of this research, aiming to develop optimal scaffolds for regenerative medicine. The need for tissue regeneration underscores understanding cellular behavior on scaffolds, especially cell adhesion to polymer fibers forming focal adhesions. Key proteins, paxillin and vinculin, regulate cell signaling, migration, and mechanotransduction in response to the extracellular environment. This study utilizes advanced microscopy, specifically the AiryScan technique, along with advanced image analysis employing the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) cluster algorithm, to investigate protein distribution during osteoblast cell adhesion to polymer fibers and glass substrates. During cell attachment to both glass and polymer fibers, a noticeable shift in the local maxima of paxillin and vinculin signals is observed at the adhesion sites. The focal adhesion sites on polymer fibers are smaller and elliptical but exhibit higher protein density than on the typical glass surface. The characteristics of focal adhesions, influenced by paxillin and vinculin, such as size and density, can potentially reflect the strength and stability of cell adhesion. Efficient adhesion correlates with well-organized, larger focal adhesions characterized by increased accumulation of paxillin and vinculin. These findings offer promising implications for enhancing scaffold design, evaluating adhesion to various substrates, and refining cellular interactions in biomedical applications.

Computational Analysis of the Effects of Fiber Deformation on the Microstructure and Permeability of Blood Oxygenator Bundles

Mechanical loads on the polymeric fibers of oxygenating bundles are commonly present due to bundle press-fitting during device assembly and blood pressure load. However, computational fluid dynamics (CFD) simulations for fiber bundle optimization neglect possible changes in microstructure due to such deformations. The aim of this study is to investigate the impact of fiber deformability on bundle microstructure and fluid dynamics mainly in terms of permeability. Fibers from commercial mats typically used for blood oxygenators were mechanically tested and based on these experimental data, a material model was developed to simulate the structural deformations the fibers undergo under press-fitting and blood pressure loads. Then, CFD simulations were performed on deformed bundle repetitive units to investigate permeability under varying loading conditions. The effects of different bundle geometric parameters on the variation of bundle permeability due to press-fitting were evaluated. Bundle press-fitting results in significant changes in microstructure that are reflected in a bundle permeability more than halved for a 15% press-fitting. This impact on permeability is present in all the simulated fiber bundles and becomes more pronounced as the pitch between fibers and thus bundle porosity decreases. Instead, the analyses on pressurized bundle show only small deformations caused by pressure load, with permeability changes below 1%. While blood pressure effects could be neglected, bundle press-fitting turns out to have a significant impact on bundle microstructure and permeability. Neglecting such microstructure variations during CFD simulations could also lead to incorrect assessment of the local fluid dynamics within the bundle.

Efficient and selective gold recovery using amine-laden polymeric fibers synthesized by a steric hindrance strategy

Various alkylamines are commonly used for efficient Au recovery; however, their high hydrophilicity can result in dissolution in water, hindering effective Au recovery and potentially causing environmental contamination. Currently, the forms in which alkylamines are immobilized on supports provide unsatisfactory Au recovery capabilities and exhibit low structural stability. This study proposes a pragmatic approach for synthesizing amine-laden polymeric fiber (ALPF) adsorbents with efficient Au recovery capabilities and superior structural stability. Polyacrylonitrile fibers (PANF) were employed as a supportive matrix to immobilize the alkylamine molecules chemically. The densely grafted amine groups on the ALPF adsorbed significant amounts of Au ions and reduced them to Au(0) crystals. This chelation–precipitation hybrid method achieved a Au recovery efficiency of nearly 100 % over a wide pH range of 1–4. In addition, it demonstrated an exceptional Au adsorption capacity of 1463 mg/g, surpassing the values reported for other adsorbents categorized by size and shape. Even in the presence of 14 different coexisting metal ions, the ALPF showed a Au recovery efficiency above 99.9 %. It also exhibited excellent reusability, maintaining a Au recovery rate of ∼91 % after 10 cycles. Furthermore, fibrous adsorbents alleviated the pressure drop in columns filled with adsorbents, thereby enabling energy-efficient and environment-friendly processes.

Palladium-Coated Submicron Electrospun Polymeric Fibers with Immobilized Uricase for Uric Acid Determination in Body Fluids

Palladium-Coated Submicron Electrospun Polymeric Fibers with Immobilized Uricase for Uric Acid Determination in Body Fluids

Elasticity and Load-Displacement Behavior of Engineered Cementitious Composites produced with Different Polymeric Fibers

Engineered Cementitious Composites (ECC) are ultra-ductile materials, and the fibers used provide superior flexibility and strain capacity. This study investigates the use of two different types of polymeric fibers, Polypropylene (PP) and Polyvinyl Alcohol (PVA), with volume fractions of 1 and 2%, and studies their effect on stress-strain relationships, load-displacement behavior, toughness, and elasticity of ECC mixes produced with two strength levels, 30 and 60 MPa. The results showed that mixtures with PVA fiber ionic coating had a better performance than those with PP fibers due to the chemical reaction between the PVA fibers and the ECC matrix. This performance was confirmed by Scanning Electronic Microscopy (SEM). For normal-strength concrete (30 MPa), the modulus of elasticity increased by 7.8 and 9.6% for mixes with PP and PVA fibers, respectively, while in high-strength mixes (60 MPa), it increased by 9.4 and 10.85%, respectively. Toughness increases with increasing matrix strength, which is associated with an increase in cement content and fiber fraction. This study also investigates the effect of incorporating a PVA solution in ECC mixes, which leads to an increase in yield stress. This behavior was observed in the stress-strain behavior of 60 MPa mixes with 2% fibers which were compared to 30 MPa mixes with 1% fibers.

3D/4D printed versatile fibre‐based wearables for embroidery, AIE‐chemosensing, and unidirectional draining

AbstractFibre‐based wearables for embroidery, chemosensing, and biofluid's unidirectional draining with good flexibility, tunability, and designability drive technological advance. However, synthetic polymer fibres are non‐degradable, threatening the environment and human health. Herein, we have developed versatile microfibre‐based wearables by combining many advantages in one platform of biodegradable polylactic acid (PLA) and melt electrowriting strategy. Diverse potential applications of PLA wearables are achieved by flexibly designing their printing files, components and structures. Three‐dimensional printing files are generated from two‐dimensional images to fabricate ‘embroidery‐like’ patterns. PLA/aggregation‐induced emission fluorogens (AIE) chemosensors exhibit colorimetric and fluorescent colour changes upon exposure to amine vapours. Janus PLA‐cotton textiles with a hydrophobic/hydrophilic structure could facilitate unidirectional draining of sweats which is favourable for the management of temperature and humidity on the surface of skin. The proposed platform can not only broaden the design possibilities in 3D/4D printing but also offer wide potential applications for functional wearables.

Study of self-heating and local strain rate in polyamide-6 and short fibre glass/polyamide-6 under tension through synchronised full-field strain and temperature measurements

This paper studies thermomechanical coupling during room-temperature tensile testing of polyamide-6 (PA6) and 50 wt% short glass fibre/PA6. The tests were performed for different fibre angles (0°, 45°, 90°), moisture contents (dry, 50%RH), and strain rates (10−4, 10−2, 10−1s−1). Digital image correlation (DIC) was coupled with infrared thermography. The contribution of the local strains, strain rates and temperatures to the global mechanical behaviour was investigated throughout deformation. The initial thermoelastic response was used to estimate the coefficient of thermal expansion. In PA6, neck development caused significant self-heating at high strain rates, differently between dry and 50%RH. In glass/PA6, however, temperature rises were always small (<+3 °C) despite local strain rate peaks in the fracture zone. This was ascribed to limited plastic deformation, as confirmed by post-mortem microscopy. The full-field data can be highly valuable for the development of advanced constitutive models for both pure polymer and short fibre composite.

Carbonate biomineralization potential of endospore-laden polymeric fibers (BioFibers) for bio-self-healing applications

This study explores the capacity and kinetics of microbially-induced calcium carbonate precipitation (MICCP) using BioFibers—endospore-laden polymeric fibers. Innovatively developed as a delivery system, BioFibers incorporate a bio-self-healing feature into quasi-brittle composites like concrete. Constructed with a load-bearing core fiber, a bio-compatible hydrogel sheath, and an outer protective shell layer, BioFibers represent a novel approach to enhancing material healing properties. BioFibers have been engineered to provide the matrix with three functionalities: autonomous self-healing, crack growth control, and damage-induced activation. The primary goal of this study was to focus on the self-healing functionality of BioFibers and evaluate the biomineralization performance through advanced material characterization techniques. In this context, we conducted quantitative and qualitative experiments to study bio-self-healing kinetics and precipitates material characterizations using thermogravimetric analysis (TGA), scanning electron microscopy equipped with energy-dispersive spectroscopy (SEM-EDS) and X-ray powder diffraction (XRD). TGA results revealed that the self-healing kinetics based on calcium carbonate precipitation were mainly exhibited by three stages: (i) endospore germination lag phase, (ii) ureolytic activity, and (iii) saturation degree of carbonate, resulting in precipitations of calcium carbonate per one activated BioFiber (with an average mass of 56.9 ± 1.4 mg) equal to: (i) 3.35–30.30 mg, (ii) 31.08–140.91 mg, and (iii) 381.39–620.08 mg, respectively. SEM imaging revealed growing calcium carbonate crystal formation, primarily vaterite, during the progression of MICCP. EDS data in the initial stage indicated traces of phosphorus, potassium, nitrogen, sodium, and sulfur, signaling the endospore germination phase. In subsequent stages, carbon, calcium, and oxygen elements dominated, confirming calcium carbonate precipitation. XRD phase analysis showed that amorphous content was the primary residue in the first stage, with 85.5% associated with organic matter and 5.6 wt% due to amorphous calcium carbonate. As the MICCP process continued, the amorphous content, mainly organic matter, decreased, reaching 23.5 wt% in the last stage. Conversely, the crystalline phase increased, with calcite accounting for 21.4 wt% and vaterite accounting for 51.7 wt% in the final stage.

On Cyclic-Fatigue Crack Growth in Carbon-Fibre-Reinforced Epoxy-Polymer Composites.

The growth of cracks between plies, i.e., delamination, in continuous fibre polymer matrix composites under cyclic-fatigue loading in operational aircraft structures has always been a very important factor, which has the potential to significantly decrease the service life of such structures. Whilst current designs are based on a 'no growth' design philosophy, delamination growth can nevertheless arise in operational aircraft and compromise structural integrity. To this end, the present paper outlines experimental and data reduction procedures for continuous fibre polymer matrix composites, based on a linear elastic fracture mechanics approach, which are capable of (a) determining and computing the fatigue crack growth (FCG) rate, da/dN, curve; (b) providing two different methods for determining the mandated worst-case FCG rate curve; and (c) calculating the fatigue threshold limit, below which no significant FCG occurs. Two data reduction procedures are proposed, which are based upon the Hartman-Schijve approach and a novel simple-scaling approach. These two different methodologies provide similar worst-case curves, and both provide an upper bound for all the experimental data. The calculated FCG threshold values as determined from both methodologies are also in very good agreement.

Low cytotoxicity, antibacterial property, and curcumin delivery performance of toughness-enhanced electrospun composite membranes based on poly(lactic acid) and MAX phase (Ti3AlC2)

MXenes, synthesized from their precursor MAX phases, have been extensively researched as additives to enhance the drug delivery performance of polymer matrices, whereas there is a limited number of previous reports on the use of MAX phases themselves for such applications. The use of MAX phases can exclude the complicated synthesis procedure and lessen resultant production and environmental costs required to convert MAX phases to MXenes. Herein, electrospun membranes of poly(lactic acid) (PLA) and a MAX phase (Ti3AlC2) have been fabricated for curcumin delivery. The composite membrane exhibits significantly higher toughness (8.82 MJ m−3) than the plasticized PLA membrane (0.63 MJ m−3) with low cytotoxicity, supporting proliferation of mouse fibroblast L929 cells. The curcumin-loaded composite membrane exhibits high water vapor transmission (∼7350 g m−2 day−1), porosity (∼85 %), water wettability, and antibacterial properties against E. coli and S. aureus. Seven-day curcumin release is enhanced from 45 % (PLA) to 67 % (composite) due to curcumin diffusion from the polymer fibers and MAX phase surface that contributes to overall increased curcumin adsorption and release sites. This work demonstrates the potential of the MAX phase to enhance both properties and curcumin delivery, promising for other eco-friendly systems for sustainable drug delivery applications.

Polymeric Microwire-Enabled Fiber Bragg Grating for Simultaneous Humidity and Temperature Sensing

Polymeric Microwire-Enabled Fiber Bragg Grating for Simultaneous Humidity and Temperature Sensing

Flexible Magnetocaloric Fiber Mats for Room-Temperature Energy Applications.

Currently, magnetocaloric refrigeration technologies are emerging as ecofriendly and more energy-efficient alternatives to conventional expansion-compression systems. However, major challenges remain. A particular concern is the mechanical properties of magnetocaloric materials, namely, their fatigue under cycling and difficulty in processing and shaping. Nevertheless, in the past few years, using multistimuli thermodynamic cycles with multicaloric refrigerants has led to higher heat-pumping efficiencies. To address simultaneously the challenges and develop a multicaloric material, in this work, we have prepared magnetocaloric-based flexible composite mats composed of micrometric electroactive (EA) polyvinylidene fluoride (PVDF) fibers with embedded magnetocaloric/strictive La(Fe,Si)13 particles by the simple and cost-effective electrospinning technique. The composite's structural characterization, using X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, and measurements of the local-scale piezoresponse, revealed a cubic NaZn13-type structure of the La(Fe,Si)13 phase and the formation of the dominant polar β-phase of the PVDF polymer. The PVDF-La(Fe,Si)13 composite showed an enhancement of the longitudinal piezoelectric coefficient (effective d33) (-11.01 pm/V) compared with the single PVDF fiber matrix (-9.36 pm/V). The main magnetic properties of La(Fe,Si)13 powder were retained in the PVDF-La(Fe,Si)13 composite, including its giant magnetocaloric effect. By retaining the unique magnetic properties of La(Fe,Si)13 embedded in the electroactive piezoelectric polymer fiber mats, we have designed a flexible, easily shapeable, and multifunctional composite enabling its potential application in multicaloric heat-pumping devices and other sensing and actuating devices.

Quantitative Dynamic AFM Hydration‐Adsorption Design for Hygroscopic and Bio‐Compatible Polymeric Nanofibers

Nanomechanical properties of bio‐compatible polymers play crucial roles in tissue engineering scaffolds and filtration devices. The hygro‐mechanical properties of those fibers have been mostly studied from a very coarse perspective, reaching a micrometer‐scale. However, at the nanoscale the mechanical response of polymeric fibers becomes more challenging due to both experimental‐theoretical limitations. In particular, the environment‐mediated mechanical response of polymer‐fibers demands advanced models that consider sub‐nanometric changes in the local structure of water‐intercalated with single‐polymer‐chains. Herein, atomic force‐microscopy (AFM) experiments, analytical theory, and simulations are combined to determine the elastic properties of the nanofibers as a function of relative humidity. The effect of morphological changes from the adsorbed water‐layer, and an ensemble of inter‐chain interaction strength and morphological changes at peak‐forces are explored. For the polyvinyl‐alcohol (PVA) nanofibers, considerable differences are found, which are strongly dependent on the molecular signatures of hydration‐adsorption at a polymer‐chain level. Here, the semi‐empirical model plays a key role in properly interpreting experiments by evaluating only a few observables, the height, phase (dissipation), and alternatively the force‐distance curves. Beyond the semi‐empirical model, an analytical approach to calculate the peak‐forces of hygroscopic materials is featured, which enables on‐the‐fly characterization of the samples, and thus the interactive adjustment of operational‐parameters.

Simple Magnetic Polymeric Ionic Liquid Nanocomposite Coated Hollow Fiber Membrane for the Determination of Lead (II) and Copper (II) in Water and Fruit Juice with Microinjection Sampling-Flame Atomic Absorption Spectrometry (MIS-FAAS)

A novel and effective adsorbent based on magnetic polymeric ionic liquid nanocomposite-coated hollow fiber membrane (MPILNC-HFM) was developed and applied for magnetic solid phase extraction of Pb (II) and Cu (II) from environmental water and fruit juice samples with microinjection sampling-flame atomic absorption spectrometry (MIS-FAAS). During extraction process, the adsorbent coated on the surface of the hollow fiber can be removed from the solution using tweezers without using a magnet. Additionally, the need to use a centrifuge during adsorption and desorption steps is also eliminated, thereby increasing the speed, simplicity, and efficiency of the extraction process. The nanocomposite characterized through Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and energy-dispersive x-ray (EDX) analyses to ensure its applicability. The experimental parameters were optimized by applying one-variable-at the-time (OVAT) approach. Under optimal conditions, limits of detection were achieved 16.5 µg L−1 for Pb (II) and 20.4 µg L−1 for Cu (II), respectively, with relative standard deviations up to 7.9% and relative recoveries in the range of 91.8%–02.2%.

A Comprehensive Review of Sustainability in Natural-Fiber-Reinforced Polymers

Fiber-reinforced polymer composites (FRCs) from renewable and biodegradable fiber and sustainable polymer resins have gained substantial attention for their potential to mitigate environmental impacts. The limitations of these composites become evident when considered in the context of high-performance engineering applications, where synthetic fiber composites like glass or carbon FRCs typically dominate. A balance between the performance of the composite and biodegradability is imperative in the pursuit of what may be termed an environmentally conscious composite. This comprehensive review article provides some insight into the sustainability of FRCs, alongside detailing the sustainability considerations at various stages—materials, performance, applications, and end of life. The discussion also covers the different types of sustainable natural fibers and the types of polymer resins with some of the current achievements in the mechanical and functional properties of such composites, followed by a broad survey of their potential applications across diverse engineering applications.

Feasibility of Recycled Carbon Fiber-Reinforced Polymer Fibers in Cementitious Composites: An Experimental Investigation

Feasibility of Recycled Carbon Fiber-Reinforced Polymer Fibers in Cementitious Composites: An Experimental Investigation

A review of polymer surface modification by cold plasmas toward bulk functionalization

AbstractPlasma surface modification of polymers is a well‐established method applied to increase the surface energy of these materials, where the capacity of cold plasmas to generate free radicals and functionalize the surface with polar groups is widely reported in the literature. This article provides a comprehensive literature review on plasma surface treatment, plasma‐induced grafting, and plasma polymerization, evaluating how these techniques can be applied to modify the bulk properties of polymers. A novel process of plasma‐induced polymer bulk functionalization in the melt state is introduced, where an atmospheric pressure plasma jet could be applied to a continuous reactive extrusion process, enhancing the production of graft copolymers for compatibilization of polymeric blends and fiber composites.

Enhancing Fatigue Resistance in Asphalt Mixtures with a Novel Additive Derived from Recycled Polymeric Fibers from End-of-Life Tyres (ELTs).

Waste-tire textile fibers (WTTF) represent a challenge for the recycling industry since there are currently very few alternatives for their use. In this study, an evaluation of the effect of a new additive developed in two granular formats from WTTF on the fatigue behavior of asphalt mixtures was performed. For the first format of the WTTF-based additive, its effect was evaluated on hot-mix asphalt (HMA), while for the second format of the additive, the effects were evaluated on stone mastic asphalt (SMA). This second format represents an alternative that allows for the total replacement of the cellulose stabilizing additive used in the reference mix. The evaluation of fatigue damage in the mixes was performed using the four-point bending beam (4PB) test specified in European standard EN 12697-24. The test results show that the asphalt mixtures manufactured with WTTF-based additives exhibited a higher capacity to resist load cycles before failure compared to the reference mixtures. Likewise, once the asphalt mixtures were evaluated in a pavement structure by means of an empirical mechanistic analysis, the pavement structures composed of asphalt mixtures with WTTF-based additives showed significant improvements in their durability for the different load axes evaluated. For an average thickness of 15 cm of asphalt mix of a pavement-type structure, the use of the WTTF additive increases the durability of the structures by up to 129% and 112% compared to the HMA and SMA reference mixtures, respectively. These results show that both formats of the WTTF-based admixture improve the fatigue damage resistance of the HMA and SMA asphalt mixtures.

Surface-mediated self-assembly of click-reactive cello-oligosaccharides for fabricating functional nonwoven fabrics

ABSTRACT Polymer fabrics are versatile materials used in various fields. Surface modification methods for hydrophobic polymer fibers have been developed to endow the materials with water wettability and functionality. Nevertheless, it remains a challenge to freely introduce functional groups to polymer fiber surfaces in a simple manner. Herein, we report the decoration of nonwoven fabric surfaces with azidated cello-oligosaccharide assemblies via molecular self-assembly. Cello-oligosaccharides with a terminal azido group were enzymatically synthesized and allowed to self-assemble in polyolefin, polyester, and vinylon nonwoven fabrics. It was found that the functional oligosaccharides formed bark-like assemblies on the nonwoven fiber surfaces, probably through heterogeneous nucleation. The hydrophilic oligosaccharide assemblies made the hydrophobic nonwoven surfaces water-wettable. Moreover, the azido group at oligosaccharide terminal was available for the post-functionalization of the modified nonwovens. In fact, an antigen was successfully conjugated to the modified nonwovens via the click chemistry. The antigen-conjugated nonwovens were useful for the specific and quantitative detection of a corresponding antibody. Our findings demonstrate the great potential of cello-oligosaccharide assembly for the functionalization of fabrics and other polymeric materials.

Investigating the Impact of Carbon Fiber as a Wheelchair Frame Material on Its Ability to Dissipate Kinetic Energy and Reduce Vibrations.

Using a wheelchair over uneven terrain generates vibrations of the human body. These vibrations result from mechanical energy impulses transferred from the ground through the wheelchair components to the user's body, which may negatively affect the quality of the wheelchair use and the user's health. This energy can be dissipated through the structure of the wheelchair frame, such as polymer and carbon fiber composites. This article aims to compare a wheelchair with an aluminum alloy frame and a carbon fiber frame in terms of reducing kinematic excitation acting on the user's body. Three wheelchairs were used in the study, one with an aluminum alloy frame (reference) and two innovative ones with composite frames. The user was sitting in the tested wheelchairs and had an accelerometer attached to their forehead. The vibrations were generated by applying impulses to the rear wheels of the wheelchair. The obtained results were analyzed and compared, especially regarding differences in the damping decrement. The research shows that using modern materials in the wheelchair frame has a beneficial effect on vibration damping. Although the frame structure and material did not significantly impact the reduction in the acceleration vector, the material and geometry had a beneficial effect on the short dissipation time of the mechanical energy generated by the kinematic excitation. Research has shown that modern construction materials, especially carbon fiber-reinforced composites, may be an alternative to traditional wheelchair suspension modules, effectively damping vibrations.