Surface Morphology Of Fibers Research Articles

Advanced 3D Electrospinning "Xspin" System: Fabrication of Bifiber Floating Oral Pharmaceutical Scaffolds for Controlled Drug Delivery.

Electrospinning has become a widely used and efficient method for manufacturing nanofibers from diverse polymers. This study introduces an advanced electrospinning technique, Xspin - a multi-functional 3D printing platform coupled with electrospinning system, integrating a customised 3D printhead, MaGIC - Multi-channeled and Guided Inner Controlling printheads. The Xspin system represents a cutting-edge fusion of electrospinning and 3D printing technologies within the realm of pharmaceutical sciences and biomaterials. This innovative platform excels in the production of novel fiber with various materials and allows for the creation of highly customized fiber structures, a capability hitherto unattainable through conventional electrospinning methodologies. By integrating the benefits of electrospinning with the precision of 3D printing, the Xspin system offers enhanced control over the scaffold morphology and drug release kinetics. Herein, we fabricated a model floating pharmaceutical dosage for the dual delivery of curcumin and ritonavir and thoroughly characterized the product. Fourier transform infrared (FTIR) spectroscopy demonstrated that curcumin chemically reacted with the polymer during the Xspin process. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) confirmed the solid-state properties of the active pharmaceutical ingredient after Xspin processing. Scanning electron microscopy (SEM) revealed the surface morphology of the Xspin-produced fibers, confirming the presence of the bifiber structure. To optimize the quality and diameter control of the electrospun fibers, a design of experiment (DoE) approach based on quality by design (QbD) principles was utilized. The bifibers expanded to approximately 10-11 times their original size after freeze-drying and effectively entrapped 87% curcumin and 84% ritonavir. In vitro release studies demonstrated that the Xspin system released 35% more ritonavir than traditional pharmaceutical pills in 2 h, with curcumin showing complete release in pH 1.2 in 5 min, simulating stomach media. Furthermore, the absorption rate of curcumin was controlled by the characteristics of the linked polymer, which enables both drugs to be absorbed at the desired time. Additionally, multivariate statistical analyses (ANOVA, pareto chart, etc.) were conducted to gain better insights and understanding of the results such as discern statistical differences among the studied groups. Overall, the Xspin system shows significant potential for manufacturing nanofiber pharmaceutical dosages with precise drug release capabilities, offering new opportunities for controlled drug delivery applications.

Highly permeable nanofibrous polyamide membranes for multi-component wastewater treatment: Exploration of multiple separation mechanism

Multi-component wastewater containing a variety of organic toxins, e.g., dyes and inorganic particulates induces serious environmental concerns, which must be addressed by innovative approaches instead of conventional chemical and physical processes, which are limited by purification efficiency, secondary pollution, and cost-effectiveness. Therefore, it is important to find new avenues of purification methods that are both sustainable and effective. Ultra-fine nanofibrous microfiltration membranes were fabricated by multi-nozzle electrospinning of polyamide-66 (PA-66) and were employed to remove 0.2-μm-nanoparticles and dyes simultaneously from wastewater through filtration and dynamic adsorption performance, in an attempt to discover a one-step filtration system for both dyes and nanoparticles. The fiber diameter and surface morphology of the nanofibrous membranes varied with the concentrations of polyamide solutions, where the ultra-fine nanofibrous membrane exhibited optimum mechanical properties at a specific concentration of PA-66 (11 wt%). The nanofibrous membranes had adsorption capabilities of 133.3 and 204.5 mg/g, respectively, against both anionic dyes (e.g., metanil yellow) and cationic dyes (e.g., chrysoidine), respectively. The membrane also selectively filtrated fine nanoparticles with a nearly 100% rejection ratio. A multiple separation mechanism, including adsorption based on electrostatic interaction, hydrogen bonding interaction, and hydrophobic interaction, as well as depth filtration, was proposed. As an applicable demonstration, the spiral wound cartridge fabricated by PA-66 nanofibrous membrane was used for a simulated multi-component wastewater treatment that contained dyes and nanoparticles of different concentrations. During the multicomponent test at flow rate 1 mL/min, a rejection rate of 97% and greater than 99% were achieved against dyes and nanoparticles, respectively.

Strength evaluation of alkali treated Sabai Grass (Eulaliopsis binata) fibers and its reinforced composites

This investigation aims to use Sabai grass fiber as a substitute reinforcement in epoxy-based composite systems, which is environment friendly and performs similarly to other natural fibers. Composite laminates are prepared with treated and untreated Sabai fibers reinforcement layered in different orientations using vacuum resin transfer molding method. Fabricated composite laminates have been evaluated for their mechanical properties (tensile strength, flexural strength, and impact strength). The effect of varying concentrations (3%, 5%, 7%, and 9 wt.%) of NaOH treatment and fiber reinforcement angle on Sabai fiber-reinforced composite laminates on its physical and mechanical properties are experimentally evaluated. The specimen made with 5 wt.% of NaOH-treated has shown maximum tensile properties because of the higher fiber concentration in the composite laminate. The thickness of fibers gets reduced as the central voids contract after the treatment. The treated strand reinforced (0°/0°/0°/0°) composite laminate has maximum tensile (103.15 MPa) and flexural strength (143 MPa). In addition, it has a higher density (1.20 g/cm3) and less porosity contents (0.70%). The untreated reinforcement has a higher impact strength. The adhesion mechanism at the fiber matrix interface has been studied using field emission scanning electron microscopy by analyzing the fiber surface morphology after treatment and in the fractured samples. The correlation of the mechanical properties of the laminate has been discussed with consideration of interfacial adhesion mechanism, fiber pull-outs, and fiber-matrix cracking phenomenon. FTIR analyses confirm the removal of the peak at around 1735 cm−1 that belongs to the acetyl group of hemicellulose attributed to C=O stretching vibration, and the peak at 1253 cm−1 is associated with the lignin, which is in close agreement with chemical analysis.

Evaluation of the application of chemically adapted gourd fibre in polyester composite fabrication

Purpose Gourd fibres (GF) are a natural biodegradable fibre material with excellent mechanical properties and high tensile strength. The use of natural fibres in composite materials has gained popularity in recent years due to their various advantages, including renewability, low cost, low density and biodegradability. Gourd fibre is one such natural fibre that has been identified as a potential reinforcement material for composites. However, it has low surface energy and hydrophobic nature, which makes it difficult to bond with matrix materials such as polyester. To overcome this problem, chemically adapted gourd fibre has been proposed as a solution. Chemical treatment is one of the most widely used methods to improve the properties of natural fibres. This research evaluates the feasibility and effectiveness of incorporating chemically adapted gourd fibre into polyester composites for industrial fabrication. The purpose of this study is to examine the application of chemically modified GF in the production of polyester composite engineering materials. Design/methodology/approach This work aims to evaluate the effectiveness of chemically adapted gourd fibre in improving the adhesion of gourd fibre with polyester resin in composite fabrication by varying the GF from 5 to 20 wt.%. The study involves the preparation of chemically treated gourd fibre through surface modification using sodium hydroxide (NaOH), permanganate (KMnO4) and acetic acid (CH3COOH) coupling agents. The mechanical properties of the modified fibre and composites were investigated. It was then characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) to determine the changes in surface morphology and functional groups. Findings FTIR characterization showed that NaOH treatment caused cellulose depolymerization and caused a significant increase in the hydroxyl and carboxyl groups, showing improved surface functional groups; KMnO4 treatment oxidized the fibre surface and caused the formation of surface oxide groups; and acetic acid treatment induced changes that primarily affected the ester and hydroxyl groups. SEM study showed that NaOH treatment changed the surface morphology of the gourd fibre, introduced voids and reduced hydrophilic tendencies. The tensile strength of the modified gourd fibres increased progressively as the concentration of the modification chemicals increased compared to the untreated fibres. Originality/value This work presents the designed composite with density, mechanical properties and microstructure, showing remarkable improvements in the engineering properties. An 181.5% improvement in tensile strength and a 56.63% increase in flexural strength were got over that of the unreinforced polyester. The findings from this work will contribute to the understanding of the potential of chemically adapted gourd fibre as a reinforcement material for composites and provide insights into the development of sustainable composite materials.

Quantifying effects of surface morphology and functional groups of carbon fibers on mass transfer coefficient in vanadium redox flow batteries

Optimization of porous electrodes has emerged as a fascinating alternative to improve the power density of redox flow batteries. While numerous studies have demonstrated the significant reduction in overpotentials due to electrode modifications, there has yet to be research that elucidates the underlying mechanism. The developed fitting model in the present study enables efficient mass transfer coefficient characterization for redox flow battery systems with sluggish reactants. Based on the newly proposed fitting model and experimental data, the present study explores the mechanism of how changes in electrode morphology and functional groups affect the mass transfer coefficient. It is found that micro-scale pores on the fiber surface, when fibers were thermally treated at 300 °C, successfully enhanced mass transfer of the reactants in the electrode likely owing to the shortened diffusion distance, while nano-scale pores, when fibers thermally treated at 400 °C, showed minor effects on mass transfer enhancement. Besides, the increment of the oxygen containing functional groups also enhanced the mass transfer rate in the diffusion layer likely attributable to the improved electrode hydrophilicity. Last, the power-law correlations for Sherwood number and Reynolds number for different electrode samples were established, enabling frontend screening in future's electrode development campaigns.

Preparation and Characterization of Polymer-Based Electrospun Nanofibers for Flexible Electronic Applications

This study was undertaken to synthesize and characterize PVDF/CB (polyvinylidene fluoride/carbon block) nanofiber composites for flexible, wearable electronic applications. Nanofibers were produced by electrospinning method and used to produce thin films. Fiber surface morphologies were investigated by FE-SEM and HR-TEM, crystalline structures by FT-IR and P-XRD, and thermal characteristics by TGA and DSC. The prepared materials are thermally stable up to 390 °C. Mechanical properties were ascertained using tensile characteristics, and results showed that the addition of carbon black (CB) powder to PVDF polymer solution decreased Young’s modulus values and reduced the dielectric constant of PVDF nanofiber films. The obtained dielectric constants of nanofibers loaded with various concentrations of CB were found from 1.4 to 2.0. Flexible electronics materials are essential for the production of wearable electronics and various biomedical engineering applications. The PVDF/CB nanofibers containing 1% showed maximum Young’s moduli of 101.29 ± 15.94. Nanofiber thin films offer various advantages, including simplicity of manufacture, low power consumption, flexibility, and exceptional stability, all of which are crucial for flexible, wearable device applications.

Structure and Properties of Cationic Chitosan Derivative Modified Bombyx mori

Abstract Cationic modification of silk fabric can highly improve its antibacterial property, but cationic modification may change the microstructure of silk fiber, and further affect its properties, thus O-methyl acrylamide quaternary ammonium salt of chitosan (NMA-HTCC), which is a kind of strong cationic chitosan derivative, was used for the modification on Bombyx mori silk fiber. The combination structure between NMA-HTCC and silk fiber was characterized by FT-IR. The surface morphology and structure of silk fiber after being treated by NMA-HTCC were investigated by SEM and XPS analysis. The crystalline structure and thermal stability of silk fibers before and after being treated were determined by XRD and DSC analysis, respectively. Then the breaking strength, breaking elongation and antibacterial properties of the silk yarns were also determined. The results indicated that the NMA-HTCC modified silk fiber clearly showed two characteristic absorption peaks at 1535 cm-1 and 1670 cm-1 due to the N-H bending and C=O stretch of the secondary amide in the acrylamidomethyl group of the NMA-HTCC molecule. The successful combination of NMA-HTCC and silk fiber was also confirmed by XPS and SEM analysis. Compared with the untreated silk sample, the diffracted intensity of the characteristic absorption peak and crystallinity of the NMA-HTCC modified silk fiber were both increased; the internal aggregation structure of the silk fiber treated with NMA-HTCC was much closer and its thermal stability was enhanced obviously. The breaking strength and elongation of silk fibers after being treated with NMA-HTCC were also significantly increased. Silk fibers treated with NMA-HTCC had excellent durable antibacterial properties against S. aureus and E. coli, even after 50 repeated launderings, with the bacterial reduction rate of the silk fibers maintained at over 95 %. The results in this research can provide the theoretical basis for the application of NMA-HTCC in the modifications of silk fabric.

Collagen membrane functionalized with magnesium oxide via room-temperature atomic layer deposition promotes osteopromotive and antimicrobial properties.

Artificial bone grafting materials such as collagen are gaining interest due to the ease of production and implantation. However, collagen must be supplemented with additional coating materials for improved osteointegration. Here, we report room-temperature atomic layer deposition (ALD) of MgO, a novel method to coat collagen membranes with MgO. Characterization techniques such as X-ray photoelectron spectroscopy, Raman spectroscopy, and electron beam dispersion mapping confirm the chemical nature of the film. Scanning electron and atomic force microscopies show the surface topography and morphology of the collagen fibers were not altered during the ALD of MgO. Slow release of magnesium ions promotes bone growth, and we show the deposited MgO film leaches trace amounts of Mg when incubated in phosphate-buffered saline at 37°C. The coated collagen membrane had a superhydrophilic surface immediately after the deposition of MgO. The film was not toxic to human cells and demonstrated antibacterial properties against bacterial biofilms. Furthermore, in vivo studies performed on calvaria rats showed MgO-coated membranes (200 and 500 ALD) elicit a higher inflammatory response, leading to an increase in angiogenesis and a greater bone formation, mainly for Col-MgO500, compared to uncoated collagen. Based on the characterization of the MgO film and in vitro and in vivo data, the MgO-coated collagen membranes are excellent candidates for guided bone regeneration.

Development of Eco-Friendly Method for Degumming of Eri Cocoons

In this study, a new eco-friendly degumming technique was developed for Eri cocoons without any chemicals. A newly developed eco-Eri degumming process was tried at 110 °C, 120 °C, 130 °C and 140 °C temperatures for 10, 20 and 30 min with soft and hard water. The novel eco-friendly degumming method was compared with the existing method of degumming viz. Soap-soda along with the enzymatic method. After degumming, weight loss per cent, changes in the fibre surface morphology concerning SEM imaging and fibre properties concerning tensile strength and elongation were studied. The eco-Eri degumming method at 130 °C for 30 min using soft water removed the maximum sericin content (degumming loss 15.7%) from Eri cocoon shells and had optimum degumming efficiency. In the eco-Eri degumming method, the degummed Eri cocoons were uniformly softened. The soap soda method of degumming resulted in 14.5% weight loss whereas enzymatic degumming resulted in a maximum of 13% weight loss (12% dosage). Enzymatic degumming significantly reduced the tensile strength but no results found in the tensile properties of Eri silk fibres were observed in new eco-friendly and soap-soda methods. SEM images indicated optimal fibre surface with the smoother surface until 130 °C, but fibre damage and fibrillation occurred at 140 °C and also with the Soap-soda method. An optimal condition for degumming Eri cocoons with the new eco-Eri degumming process is 130 °C for 30 min using soft water. The eco-Eri degumming method is better compared to other methods used presently in the industry.

FABRICATION OF SILK FIBROIN AND FLUORESCENT SILK FIBROIN FIBERS VIA ELECTROSPINNING

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 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 addition of fluoresceine sodium (FS) as 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.

Nanomechanical properties of sized and de-sized carbon fiber reinforced polypropylene composites

Most of the research to date has focused on tailoring the interphase adhesion by controlling the degree of chemical bonding between fiber and resin. However, recent studies suggest that apart from chemical bonding, mechanical interlocking plays a crucial role to enhance the interphase thickness and hence the interfacial shear strength. In this study, the effect of textured carbon fiber surface on the interphase thickness, and interfacial shear strength has been studied and analyzed. The hot water was used to remove the epoxy-based sizing agent from the carbon fiber (sized CF) surface and thereby to create a textured surface morphology in de-sized one (De-sized CF). To study the distinctions of the interphase between sized and de-sized CF/PP composites, the Derjaguin-Muller-Toporov (DMT) modulus by Peak Force Quantitative Nano-Mechanics (PF-QNM) was applied to determine the interphase thickness and its nanomechanical properties. It was found that no chemical changes occurred after hot water treatment albeit the surface morphology of de-sized carbon fiber became textured. The average interphase thickness in de-sized CF/PP composites was found to be 84.17% higher (212.9 ± 21 nm) as compared to 115.6 ± 21 nm in sized CF/PP composites. This study shows the potential for using mechanical interlocking effects without significantly affecting the chemical bonding, to improve the interphase thickness in fiber reinforced composites.

Optimization of the novel jute retting process to enhance the fiber quality for textile applications

This study introduces an innovative chemical retting approach, systematically optimized via Grey relational analysis, to achieve jute fibers that exhibit desirable characteristics of softness, high tensile strength, and suitability for spinning, with a particular focus on their application in the apparel industry. In this study, the effect of alkali treatment (alkali concentration, temperature and duration of retting) on jute fiber's chemical composition and mechanical characteristics was investigated. Jute fibers were treated at three concentrations (5 %, 10 %, 15 %) of alkali, at three different temperature (30 °C, 60 °C, & 90 °C) and for three different retting duration (12 h, 24 h, & 36 h). The surface morphology and crystallinity of fibers were analyzed using optical microscopy, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The fiber linear density and mechanical characteristics were also tested. The multi-response optimization of all the factors and the responses was investigated using the Grey relational analysis. The results showed that the fiber surface morphology and crystallinity increase with an increase in alkali concentration, retting time, and temperature. Chemical retting treatment also improved the fiber linear density and tensile strength. The finest fibers which were obtained in this research had a linear density of 2.18 Tex with a tenacity of 53.02 cN/tex and elongation of 4.54 %. The spinnable jute fibers were achieved after this treatment with excellent characteristics.

Development of non-combustible weaveable yarn through oxidative control of a textile acrylic fibre

Acrylic fibre is considered to be artificial wool in the textile industry, but in contrast with natural wool, it vigorously burns producing black smoke and toxic gases. This not only has hindered its technical applications, but also poses safety risks to the end-users of acrylic-based products. This research aims at enhancing the fire-retardancy of acrylic yarns using a facile thermal stabilisation process which is based on controlling the oxidation temperature and residence period. To this end, acrylic yarns are thermally processed according to six different time and temperature profiles ranging from 220 to 280 °C, with residence periods ranging from 22 to 28 min. The oxidised yarns were characterised using FTIR, DSC, and TGA techniques and the effects of the oxidative thermal treatment on physical characterises, and surface morphology of yarns and fibres were discussed. The results showed that the acrylic yarn undergone the oxidation process based on 240–255–270–280 °C heating profile for 28 min at each step had a sufficiently high degree of cyclisation with an excellent fire retardancy. Furthermore, the stabilised acrylic yarn was strong enough to be woven into a plain weave fabric using a laboratory scale loom while displaying non-combustible behaviour during cyclic exposure to flame. These results present a novel pathway for the development of a low cost, non-combustible fabric ideally suited for applications in extreme environments.

The Isolation and Characterization of Cellulose Nano crystals from Baobab Pod Fibres using Acid Hydrolysis

In this research, cellulose nanocrystals were isolated from locally grown baobab pod fibres. Fibres were treated chemically using NaOH and then hydrolysed using Nitric acid. The effect of NaOH treatment and acid hydrolysis on surface morphology, crystallinity, and thermal properties of fibres were investigated using Fourier Transform Infrared (FTIR), Scanning electron microscopy/Energy dispersive X-ray spectroscopy (SEM/EDS), X-ray Diffraction(XRD) and Thermogravimetric analysis (TGA/DTA). From the results evaluated, cellulose content of 17.9 % was recorded after NaOH treatment and 25.3 % was recorded after acid hydrolysis, the crystallite size was found to be 3.003 nm and thermal stability of the fibre was enhanced after chemical treatment and acid hydrolysis. Based on the results obtained, it shows that nanocellulose hydrolyzed from baobab pod fibres has excellent properties for use as polymer reinforcement and for other engineering applications.

Chopped Areca Nut Fibers as Filler in Epoxy Matrix: Mechanical and Tribological Studies

In the current investigation, fibers extracted from the areca nut tree husk were either used unprocessed or processed with an alkaline treatment by being submerged in a 5 % sodium hydroxide solution. The average length of the areca fibers used in this work is 30 mm. Compression molding is used to create the composite out of an epoxy matrix with fibers added at 10, 15, 20 and 25 weight percent. The composites were tested for tensile strength, flexural modulus, Charpy impact, and shore D hardness, all of which showed the significant advantage acquired with quantity of fibers and fiber treatment. Pin on disc tribometer was used to conduct tribological tests on the treated fiber composites to analyse how the fiber-matrix bonding improved with an increase in fiber content. The primary shortcoming of the fibers is their relatively low elongation, which, even after treatment, hardly approaches 4 %. This indicates that the fibers are not uniform in length and prevents direct comparison to comparable composites containing a similar volume and length of natural fibers. The mechanical qualities of materials made with alkali treated chopped areca fibers where found to be enhanced when it was at 20 % volume fraction. A linear increment in values where observed in samples till 20 % volume fraction and a decrement with further increase in volume fraction. In the case of tribological evaluations, lesser values or wears were obtained at combination III for all the 3 loads, 10N, 15N and 20N. HIGHLIGHTS Three different amounts of fibers, namely 10, 15, 20 and 25 wt%, have been introduced in an epoxy matrix, fabricating the composite by compression molding. The composites were subjected to tensile, flexural, Charpy impact and Shore D hardness testing, which all demonstrated the considerable advantage obtained with quantity of fibers and fiber treatment, except in the case of hardness, where limited advantages were encountered. Also wear tests were carried out on treated fiber composites and surface morphology of the worn-out samples was studies, which demonstrated the improvement in fiber-matrix bonding obtained with the growing amounts of fibers. From the results on composites testing, it is evident that the areca nut husk fiber/epoxy polymer composites with an amount of short (30 mm length) random reinforcement introduced of 20 wt%, exhibits the highest peak mechanical properties among all the calculated properties. GRAPHICAL ABSTRACT

Atomistic Construction of Silicon Nitride Ceramic Fiber Molecular Model and Investigation of Its Mechanical Properties Based on Molecular Dynamics Simulations.

Molecular simulations are currently receiving significant attention for their ability to offer a microscopic perspective that explains macroscopic phenomena. An essential aspect is the accurate characterization of molecular structural parameters and the development of realistic numerical models. This study investigates the surface morphology and elemental distribution of silicon nitride fibers through TEM and EDS, and SEM and EDS analyses. Utilizing a customized molecular dynamics approach, molecular models of amorphous and multi-interface silicon nitride fibers with complex structures were constructed. Tensile simulations were conducted to explore correlations between performance and molecular structural composition. The results demonstrate successful construction of molecular models with amorphous, amorphous-crystalline interface, and mixed crystalline structures. Mechanical property characterization reveal the following findings: (1) The nonuniform and irregular amorphous structure causes stress concentration and crack formation under applied stress. Increased density enhances material strength but leads to higher crack sensitivity. (2) Incorporating a crystalline reinforcement phase without interfacial crosslinking increases free volume and relative tensile strength, improving toughness and reducing crack susceptibility. (3) Crosslinked interfaces effectively enhance load transfer in transitional regions, strengthening the material's tensile strength, while increased density simultaneously reduces crack propagation.

Improving the Performance of Poly(caprolactone)-Cellulose Acetate-Tannic Acid Tubular Scaffolds by Mussel-Inspired Coating.

Small-diameter artificial blood vessels are increasingly being used in clinical practice. However, these vessels are prone to thrombus, and it is necessary to improve blood compatibility. Surface coating is one of the commonly used methods in this regard. Inspired by the biomimicry of mussels, the use of deposition technology to obtain coating coverage on the surface of fibers has significantly piqued the interest of researchers recently. In this study, tubular scaffolds consisting of a composite of poly(caprolactone), cellulose acetate, and tannic acid (TA) were electrospun, and then the scaffolds were treated with different Fe(III) solutions (iron(III) chloride hexahydrate (FeCl3'6H2O)) to obtain four tubular scaffolds: F0, F5, F15, and F45. According to scanning electron microscopy (SEM) and field emission-SEM results, TA/Fe(III) complex is coated on the fiber of the scaffold after post-treatment; the fiber surface morphology changes with different Fe(III) concentrations. This provides designability to the performance of tubular scaffolds. The tensile strength of the F5 tubular scaffold (3.33 MPa) is higher than that of F45 (3.14 MPa), while the strain (83.9%) of the F45 tubular stent was 2.26 times that of the F5 (37.2%). In addition, cytotoxicity and antithrombotic performance were evaluated. The test results show that surface TA/Fe(III) coating treatment can affect the cytotoxicity and anticoagulation performance of the scaffold surface. The biomimetic TA/Fe(III) coating of mussels used in this study improves the performance of artificial blood vessels.

Modification and Enhancing Contribution of Fiber to Asphalt Binders and Their Corresponding Mixtures: A Study of Viscoelastic Properties.

The performance of asphalt binders and asphalt mixtures can be enhanced by the inclusion of fiber. The viscoelastic characteristics of fiber-reinforced asphalt binders and their corresponding mixtures were characterized in this study. To generate fiber-reinforced asphalt samples for dynamic shear rheometer (DSR) tests, polypropylene fibers (PPFs), polyester fibers (PFs), and lignin fibers (LFs) were added into modified asphalt with a ratio of 5wt%. Indirect tensile resilience tests were conducted on the fiber-reinforced asphalt mixture with Marshall samples, which was prepared with a 6.4% of bitumen/aggregate ratio. The addition of fiber can increase the anti-rutting performance of asphalt binders, and also reduce the anti-fatigue performance of asphalt binders to varying degrees. Viscoelastic properties of the fiber-reinforced asphalt binders are highly dependent on the shape of the used fiber. The resistance of the fiber-reinforced asphalt binders to rutting at high temperatures increases with the roughness degree of the fiber's surface morphology. PPF-reinforced asphalt binders surpass the others in terms of anti-rutting capabilities. The high-temperature deformation resistance of the PPF-reinforced asphalt mixture is stronger, whereas the low-temperature crack resistance of the PF-reinforced asphalt mixture is stronger, which can be observed from the master curve of indirect tensile resilient modulus.

A study of the wear resistance of carbon fiber composites deposited using an alkaline-based palladium-free electroless plating method

To improve the wear resistance of carbon fibers, we optimized the ratio of the plating solution components and developed a new and economical alkaline-based palladium-free method to evenly coat carbon fibers with nickel–phosphorus alloy. The carbon fibers coated with composites deposited using this method demonstrated enhanced frictional properties. Next, the coating thickness was adjusted and tested, and the effects of coating thickness and surface morphology on the frictional properties of carbon fibers were studied to determine the most suitable coating thickness. The friction coefficient and wear rate of the coated composites were analyzed using a friction and wear testing machine under non-lubricated sliding conditions while controlling the friction duration. The surface morphology, elemental composition and oxidation transfer film morphology of carbon fibers with various coating thicknesses were characterized using field-emission scanning electron microscopy and energy-dispersive X-ray photoelectron spectroscopy. The results showed that the oxidation transfer film substantially prevented the internal fibers from participating in the friction process, and the friction coefficient and wear rate decreased as the uniform coverage area of the transfer film increased. The surface wear mechanism of the carbon fibers was analyzed, and abrasive wear was found to be the main wear mechanism. The findings of this study provide a theoretical and experimental reference for reducing the friction and improving the wear resistance of carbon fibers.

A new strategy for improvement of interface and mechanical properties of carbon fiber/epoxy composites by grafting graphene oxide onto carbon fiber with hyperbranched polymers via thiol‐ene click chemistry

AbstractFor the purpose of improving the interface and mechanical properties of carbon fiber reinforced polymer (CFRP) composites, a new strategy was proposed to graft the graphene oxide (GO) onto carbon fiber (CF) surface fast and effectively via thiol‐ene click chemistry reaction using vinyl‐terminated hyperbranched polyester (VHBP) as bridging agent. The successful synthesis of the CF‐VHBP‐GO hybrid reinforcement was verified through Fourier transform infrared spectroscopy (FT‐IR), x‐ray photoelectron spectroscope, thermogravimetric analysis, and scanning electron microscopy. The simultaneous introduction of GO and hyperbranched polymers changed the fiber surface morphology and improved the wettability and surface energy of CF. Judging from the results of the micro‐droplet test, the interfacial shear strength for epoxy (EP) based composite reinforced with CF‐VHBP‐GO was significantly increased by 137.8% compared to untreated CF/EP composite owing to the synergistic effect of VHBP and GO. In addition, the tensile and flexural strength for CF‐VHBP‐GO/EP composite were improved by 47.6% and 65.8%, respectively, compared to untreated CF/EP composite, respectively. This work offers a promising technique for developing high‐performance CF composites with excellent interface properties.