Surface Structure Of Fibers Research Articles

Mechanical, structural, and chemical properties of unmodified and iron-modified phosphate glass fibers based on natural phosphate and kaolin clay

Earlier research has reported that the phosphate glass fibers can be used as fertilizer with slow and controlled release of nutrient ions due to the controllable degradability in aqueous environments. In this study, two series of phosphate glasses were prepared and successfully stretched to continuous monofilaments fibers with a fixed spinning speed. The first series includes four phosphate glass fibers compositions based on natural phosphate and kaolin clay in appropriate amounts. Mechanical properties in terms of tensile strength and tensile modulus were dramatically increased with the progressive addition of kaolin clay. PCA statistical analysis carried out to study the effect of the chemical composition on the mechanical performance of fibers showed a strong correlation between Al2O3, SiO2 and Fe2O3 and K2O oxides and the evolution of tensile strength. The second series is based on the selection of the composition with significant mechanical properties to which increasing amounts of Fe2O3 oxide (3, 3.5 and 4 mol%) were added. The effect of Fe2O3 addition on surface morphology, structure, mechanical properties and dissolution behavior of fibers was studied. The results indicate that the addition of 4 mol% of Fe2O3 increased the tensile strength up to 1612 ± 177 MPa and decreased the dissolution rate of the fibers in distilled water under conditions of temperature, time and pH. These results can be explained by the formation of more covalent P–O–Fe bonds that are more resistant in aqueous media.

Investigation of the Extraction Processes and Performance Properties of Kudzu Fibers

ABSTRACT Kudzu plants have become increasingly invasive in the US, yet are not highly utilized. Intending to produce eco-friendly fibers, this research used fresh kudzu vines to produce fibers by four different processes: boiling, retting, enzymatic and mild chemical processes. Two types of fibers resulted from each process – soft and woody. Unlike more popularly used natural bast fibers such as linen, there is no standard description of the surface structure of kudzu fibers established, this report provides a broad microscopic analysis and images for kudzu fibers. Resultant kudzu fibers, with an average length of 20–300 cm, exhibited a breaking load of 4–20 kg/tex and a breaking elongation of 22.67–37.94%. Results suggest that soft kudzu fibers are promising for apparel and use in fiber-reinforced composites while woody fiber as basketry or paper.

Interfacial modification of carbon fiber by carbon nanotube gas-phase dispersion

The interfacial bonding between carbon fiber(CF) and matrix is one of the important technical difficulties during the development of CF. In the paper, a physical modification method of rapidly spraying CF surface by carbon nanotubes(CNTs) gas-phase dispersion was adopted to strengthen the interfacial bonding between CF and matrix. SEM was used to observe the structure of fiber surface and the distribution of CNTs. And the mechanical and thermoelectric properties of the formed CF composite specimens were measured. The results showed that interlaminar shear strength, tensile strength and compression strength of the CF composite fibers increased by 12.07%, 8.73% and 13.83%, and CF composites treated with CNTs had higher thermal diffusivity and lower resistivity than before. It has good application significance for modification and reinforcement of CF and CF composites.

Multiscale characterisation of single synthetic fibres: Surface morphology and nanomechanical properties

HypothesisThermal through-air bonding process and slip additive treatment affect fibre surface structure and nanomechanical properties, which is extremely difficult to characterise on a single-fibre level. ExperimentsOptical microscopy (OM) was applied to study the effect of air-through bonding, spunbonding, and crimping on fibre geometry and general appearance. A “spray-on” method developed here using a custom-designed fibre holder allowed a direct measurement of static contact angles of water droplets on single fibres. Scanning electron microscopy (SEM) showed different morphological features on the fibre due to the nonwoven fabric-making process and additive treatment. Synchrotron X-ray diffraction (XRD) was applied to study the effect of erucamide presence on polypropylene (PP) fibre crystal structure. Atomic force microscopy (AFM) imaging provided complementary characterization of fibre topographic features such as average surface roughness, along with adhesion force mapping by quantitative nanomechanical (QNM) AFM imaging. FindingsOur results show the effect of nonwoven making process and surfactant additive treatment on the fibre surface structure and nanomechanical properties. Wettability experiment on the single fibre revealed the hydrophobic nature of all the synthetic fibres. For polyethylene/polyethylene terephthalate (PE/PET) bicomponent single fibres, the polyethylene sheath was found to possess fibrillar microstructure - typical for drawn fibres, whereas the fibres entangled in nonwoven fabrics exhibited a uniform, porous surface morphology attributed to the through-air process. Adhesion force mapping allowed us to correlate fibre nanomechanical properties with its topography, with surface pore interiors showing higher adhesion than the flat polyethylene region. Furthermore, on the polypropylene (PP) fibre surface treated with erucamide (13-cis-docosenamide; a common slip additive used in polyolefin film processing), we observed overlapping multilayers consisting of 4 nm erucamide bilayers, attributed to the slip additive migration onto the fibre surface. XRD measurements of the fibres did not detect the presence of erucamide; however, AFM imaging provided evidence for its migration to the fibre surface, imparting influence on the surface structure and adhesive properties of the fibre. Single-fibre AFM imaging also allowed a detailed analysis of different surface roughness parameters, revealing that both through-air bonding in the nonwoven making process and the slip additive (erucamide) treatment affected the fibre surface roughness. The wettability, surface morphology, and adhesion properties from this study, obtained with unprecedented resolution and details on single fibres, are valuable to informing rational design of fibre processing for fibre optimal properties, critically important in many industrial applications.

Targeted morphology of copper oxide based electrospun nanofibers

In this work, CuO-based nanofibers were synthesized via electrospinning. Smooth, defect-free fibers with a diameter of 261 ± 63 nm were fabricated and characterized. Thermal treatment under air at 823 K transformed the smooth nanofibers to a network of segmented, macroporous CuO nanoparticles with an average fiber diameter of 160 ± 41 nm and a crystallite size of 55.4 nm. The effects of solution properties (polymer molecular weight, polymer/metal concentration, and solvent identity) and processing conditions (voltage, tip-to-collector distance, extrusion rate, and humidity) were also investigated. Solution properties were found to strongly influence viscosity, conductivity, dielectric constant, density, and surface tension, which invariably affected fiber dimension, morphology and surface structure. Fibers as thick as 536 nm and as thin as 70 nm with cylindrical and fused structures were produced by manipulating the solution properties. Processing conditions were found to moderately affect fiber uniformity and fiber diameter.

Interface improvement of carbon fiber/PMMA resin composites by fiber surface coating

The surface of the carbon fiber (CF) has been pretreated by liquid phase deposition of microcrystalline cellulose (MCC).X-ray photoelectron spectroscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM) have beenused to analyze and characterize the surface morphology and structure of carbon fiber, and the shear strength test and SEMobservation of single fiber interface have been performed. The interfacial adhesion properties of carbon fiber compositeshave been investigated. The results have shown that the pretreated carbon fiber deposition increases the shear strength of thesingle fiber interface by 259.3%. The analysis results have shown that the improvement of interfacial shear strength has beenrelated to the mechanical riveting between the fibers/resin and the force of the interface. Pretreatment has increased thecarboxyl groups on the surface of carbon fibers and forms hydrogen bonds between carboxyl groups, thereby improving theinterfacial properties of carbon fiber composites.

Evaluation of oil sorption kinetics behavior and wetting characteristic of cattail fiber

In this study, the effect of packing density, oil type and temperature on the sorption kinetics behavior of cattail fiber was investigated based on Washburn theory by capillary rise test. It was found that higher packing density resulted in lower oil sorption capacity due to the less available space among fibers. The sorption coefficient to different oils which represented the sorption rate exhibited large difference with various packing densities. The results illustrated that when the packing density was 0.04 g/cm3, the cattail fiber showed higher oil sorption capacity and faster oil sorption rate. With regards to the temperature, results revealed that at the packing density of 0.06 g/cm3, the oil sorption capacity of cattail fiber showed little difference when the temperature ranged from 20 to 80 °C. However, the sorption coefficient depicted almost linear enhancement when higher temperature was applied. Moreover, the wetting characteristics of single cattail fiber to three test oils were performed by drop-on-fiber test. It was concluded that three test oils all displayed barrel-shaped droplets on single fiber with the smallest size for diesel oil and the largest for engine oil. Oil drops of vegetable oil and engine oil on single cattail fiber presented a dynamic flow process where smaller droplets converge into large ones. The unique wetting characteristic of cattail fiber was supposed to result from the open-cavity surface structure of cattail fiber.

The characterization tensile and thermal properties of hibiscus tiliaceus cellulose fibers

In our study, hibiscus tiliaceus (HT) fibers were treated with potassium hydroxide (KOH) 8% for two hours at ambient temperature. The tensile strength and thermal properties of the treated fibers were examined by using tensile test and Thermogravimetric analysis (TGA). The surface structure of the hibiscus tiliaceus fibers were analyzed using Scanning Electronic Microscopy (SEM). Experimental results revealed that under KOH treatment, the tensile strength increased up to 5144.9 MPa, resistance thermal and cellulose of the fibers become increased; due to hemicellulose content were reduced of the fibers. SEM images show that after alkali, the hibiscus tiliaceus fibers surface becomes clear, fibril and rougher.

Preparation of graphene oxide/polyacrylonitrile fiber from graphene oxide solution with high dispersivity

ABSTRACTThis paper reports the grafting of polyacrylonitrile (PAN) onto the functional groups of graphene oxide (GO) by bridge linkers, toluene diisocyanate (TDI) in high concentration GO solution to prepare GO/PAN composite fiber. In this study, it was discovered that GO solution with high dispersivity is rich in oxygen-containing functional groups and the well-dispersed GO exists as multi-layer graphenes and does not display liquid crystallinity. These factors contribute to the high dispersivity of the GO solution and spinning difficulty. To overcome these issues, TDI was used to bridge the easily spinnable PAN and rich oxygen-containing functional groups in GO. IR spectra confirmed that the TDI successfully linked PAN and GO with enhanced binding. Wet spinning was then used to spin the bridge-linked GO solution into GO/PAN composite fiber. SEM and Raman spectroscopy were used to characterize the fiber surface and carbon structure, respectively. The GO/PAN composite fiber prepared by wet spinning in an ethanol coagulation bath exhibited less folding, higher compactness, a lower degree of structural defects, and a uniform distribution of high GO content in the fiber. The interconnected graphene network shows potential for application as a graphene-based composite fiber with high thermal conductivity.

Controlling the surface structure, mechanical properties, crystallinity, and piezoelectric properties of electrospun PVDF nanofibers by maneuvering molecular weight

ABSTRACTPolyvinylidene fluoride (PVDF) is a significant polymer in the formation of nanofiber webs via the electrospinning technique. In this paper, three PVDF-wrinkled fiber webs with different molecular weights (MWs) (180000, 275000, and 530000) were generated via the electrospinning method by using tetrahydrofuran/N,N-dimethylformamide at the solvent ratio of 1:1 as a mixed solvent. The formation mechanism of the wrinkled electrospun PVDF fibers is demonstrated. Furthermore, the relationships between the MW and the surface structure, mechanical properties, crystalline phases, and piezoelectric properties of electrospun PVDF fibers are comprehensively investigated. The results reported that the surface structure, mechanical properties, crystalline phases, and piezoelectric properties of wrinkled electrospun PVDF fibers can be affected intensely by maneuvering the MW. We believe this study can be served as a good reference for the effect of MW on the morphology and properties of electrospun fibers.

Preparation of Reversible Photoresponsive Poly(SPA‐co‐MMA) Films by Electrospinning: A Possible Route to Smart Materials for Regulating Wettability and Humidity

AbstractThe control of surrounding humidity by porous films is an interesting aspect for improving human comfort. Especially, light triggered humidity control is of relevance because light stimulus is contactless so that reducing the impact on both materials and surroundings. In this work, reversible light responsive films with tunable wettability and the ability of regulating surrounding humidity are developed from acrylated spiropyran (SPA)–methyl methacrylate (MMA) copolymer by electrospinning. The electrospun films for regulating wettability and surrounding humidity can be reversibly manipulated by the simple switch of UV and visible light irradiation because of the unique transformation between polar ring‐opened status and nonpolar ring‐closed status of spiropyran units. Morphology analyses and Cassie theory are used to explain this phenomenon and it is found that surface microstructure and effective chemical composition of the film surface can both significantly influence the reversible variation range of the value of surrounding humidity and surface wettability. The results show that the ability to regulate humidity of 40 wt% poly(SPA‐co‐MMA) film possessing bead‐on‐string fiber surface structure is the best.

Enhancing interfacial strength of epoxy resin composites via evolving hyperbranched amino-terminated POSS on carbon fiber surface

A self-synthesized octa(γ-chloropropyl) polyhedral oligomeric silsesquioxanes (POSS) and its evolutionary amino-terminated hyperbranched structure were introduced onto the carbon fibers (CFs) surface (CF-Gn-POSS-NH2, n = 1, 2 and 3) by chemically and successively grafting method to improve the interfacial properties of CFs/epoxy composite. The fiber surface structures could be tuned through regulating grafting generation (n) of CF-Gn-POSS-NH2, and the polarity and roughness of CF surface increased with the incremental dendritic generation number. Interfacial shear strength (IFSS), interlaminar shear strength (ILSS) and dynamic mechanical properties of the functionalized CFs composites improved as the grafting generation increased, which may be attributed to the varying degrees of chemical interaction, mechanical interlocking and resin wettability provided by hyperbranched Gn-POSS-NH2 interface. Moreover, the interfacial structure has been also speculated and analyzed.

Grafting Halloysite Nanotubes with Amino or Carboxyl Groups onto Carbon Fiber Surface for Excellent Interfacial Properties of Silicone Resin Composites.

The quality of interphase in carbon fibers (CFs) composites makes a key contribution to overall performance of composites. Here, we achieved for the first time the chemical grafting of halloysite nanotubes (HNTs) with amino or carboxyl groups onto the CFs surface aiming to increase composites interfacial strength. HNTs were grafted using 3-aminopropyltriethoxysilane (APS) followed by succinic anhydride treatment, and HNTs with amino groups (HNT–NH2) or carboxyl groups (HNT–COOH) were separately introduced into the interphase of composites. Functional groups of HNTs and fiber surface structures were characterized, which confirmed the modification success. The wettability between the modified CFs and resin have been enhanced obviously based on the improved fiber polarity and enhanced surface roughness by the introduced two functionalized HNTs with the uniform distributions onto fiber surface. Moreover, interfacial properties and anti-hydrothermal aging behaviors of modified methylphenylsilicone resin (MPSR) composites were improved significantly, especially for HNT–COOH grafting. In addition, the interfacial reinforcement mechanisms for untreated and modified CF composites are discussed and compared.

Controlling the surface structure of electrospun fibers: Effect on endothelial cells and blood coagulation

The influence of nano- or micron-sized structures on polymer films as well as the impact of fiber diameter of electrospun membranes on endothelial cell (EC) and blood response has been studied for vascular tissue engineering applications. However, the influence of surface structures on micron-sized fibers on endothelial cells and blood interaction is currently not known. In this work, electrospun membranes with distinct fiber surface structures were designed to study their influence on the endothelial cell viability and thrombogenicity. The thermodynamically derived Hansen-solubility-parameters model accurately predicted the formation of solvent dependent fiber surface structured poly(caprolactone) membranes. The electrospun membranes composed of microfibers (MF) or structured MF were of similar fiber diameter, macroscopic roughness, wettability, and elastic modulus. In vitro evaluation with ECs demonstrated that cell proliferation and morphology were not affected by the fiber surface structure. Similarly, investigating the blood response to the fiber meshes showed comparable fibrin network formation and platelet activation on MF and structured MF. Even though the presented results provide evidence that surface structures on MF appear neither to affect EC viability nor blood coagulation, they shed light on the complexity and challenges when studying biology-material interactions. They thereby contribute to the understanding of EC and blood-material interaction on electrospun membranes.

Ultrasonic scouring as a pretreatment of wool and its application in low-temperature dyeing

Ultrasonic technology has shown the potential to reduce the cost and environmental impact of textile wet processing. This work investigates the effects of ultrasonic irradiation as a pretreatment on wool and its application in low-temperature dyeing. A significant increase in dye uptake and color strength was observed on the fabric ultrasonically pretreated at 40 kHz, followed by that at 80 kHz and the conventionally treated sample, in both acid dyeing and reactive dyeing. This could be due to the changes of the fiber surface structure and modification of the chemical structure in the cell membrane complex as a result of ultrasonic pretreatment. In acid dyeing, a 20% increase in dye uptake was achieved at 70℃ upon applying ultrasonic pretreatment at 40 kHz. With the assistance of a leveling agent, 80% dye uptake of the fabric treated with ultrasonics at 40 kHz was measured at 70℃ in reactive dyeing. Ultrasonic pretreatment can be applied in raw wool scouring and fabric scouring to achieve an efficient dye uptake, and these are also discussed in this paper.

Comparison of the Conventional and Electroenhanced Direct-Immersion Solid-Phase Microextraction for Sampling of Nicotine in Biological Fluids of the Human Body.

A stainless steel fiber was made porous and adhesive by platinization and then coated by nanostructured polypyrrole (PPy), using an appropriate electrophoretic deposition (EPD) method. The morphological surface structure and functional groups of the PPy-coated fiber were studied using SEM (Scanning electron microscope) instrument. The prepared fiber was used for comparison of direct immersion (DI) and electroenhanced direct immersion solid-phase microextraction (EE-DI-SPME) of nicotine in human plasma and urine samples followed by gas chromatography flame ionization detector (GC-FID) determination. The effects of the influential experimental parameters on the efficiency of the DI-SPME and EE-DI-SPME methods, including the pH and ionic strength of the sample solution, applied Direct current (DC) voltage, extraction temperature and time and stirring rate, were optimized. Under the optimal conditions, the calibration curves for the DI-SPME-GC-FID and EE-DI-SPME-GC-FID methods were linear over the ranges of 0.1–10.0 μg mL−1 and 0.001–10.0 μg mL−1, respectively. The relative standard deviations (RSDs, n = 6) were found to be 6.1% and 4.6% for the DI and EE strategies, respectively. The LODs (limit of detection) of the DI-SPME-GC-FID and EE-DI-SPME-GC-FID methods were found to be 10 and 0.3 ng mL−1, respectively. The relative recovery values (for the analysis of 1 µg mL−1 nicotine) were found to be 91–110% for EE-DI-SPME and 75–105% for DI-SPME. The enrichment factors for DI-SPME and EE-DI-SPME sampling were obtained as 38,734 and 50,597, respectively. The results indicated that EE-SPME was more efficient for quantitation of nicotine in biological fluids. The developed procedure was successfully carried out for the extraction and measurement of nicotine in real plasma and urine samples.

Tuning interfacial strength of silicone resin composites by varying the grafting density of octamaleamic acid-POSS modified onto carbon fiber

Octamaleamic acid-polyhedral oligomeric silsesquioxanes (OMA-POSS) were chemically modified onto the surface of carbon fibers (CFs) by a facile and high efficient two-step method. CF was grafted with hydroxyl groups via aryl diazonium reaction, and then covalently functionalized with OMA-POSS. The grafting density could be tuned through the concentration of OMA-POSS. Fiber surface structures were characterized by confirming the covalent bonding nature between OMA-POSS and CF. OMA-POSS was scattered on CF surface uniformly, and fiber polarity and roughness increased with the increased grafting density of OMA-POSS. Interfacial shear strength (IFSS) and interlaminar shear strength (ILSS) of the modified CFs composites enhanced as the grafting density grew, which could be ascribed to OMA-POSS interface with providing different degrees of chemical bonding and mechanical interlocking. Moreover, the hydrothermal aging resistance of composites is highly dependent on the amounts of the introduced OMA-POSS. The storage modulus and the glass transition temperature could increase by 8 GPa and 14 °C based on dynamic mechanical analysis testing. In addition, the interfacial reinforcing mechanisms have been also analyzed, and surface modification maintained fiber tensile strength.

Fabrication and Properties of <i>Panicum repens</i> Reinforced Cement

This research aims to fabrication and evaluation the properties of cement reinforcement made from Panicumrepens. The research is divided into two parts are as follows; to determined the optimal ratio selection, and to compare the properties of Panicumrepens reinforced cement, and without grasses by using the optimal ratio. The raw materials used in this research were cut in length of 2.0-2.5 cm. In this research was determined the properties of Panicumrepens reinforced cement in terms of bulk density, water absorption, and compressive strength. The influence of fibers soaked with 5% of sodium hydroxide concentration was also conducted in this research. The surface structure and chemical characteristics of fibers used to produce reinforced cement were observed by using scanning electron microscope (SEM), and energy dispersive x-ray spectrometer (EDS), respectively. Moreover, relationships of information collected from this research were concerned. Furthermore, the addition of Panicumrepens fibers could improve the flexural strength of composite materials.

Coloration of polyester fiber with natural dye henna (Lawsonia inermis L.) without using mordant: a new approach towards a cleaner production

The demand of natural colorants for the dyeing of textile fibers has been increasing gradually in recent years due to a growing global ecological awareness as well as a greater emphasis on a cleaner and greener production process. The eco-friendly dyeing of polyester fiber with natural dye henna is a novel approach that has extensively been studied in this article. To this end, the dyeing of polyester fiber with henna dye was conducted at different temperatures without using hazardous metallic mordants. Then the dyeing performance was investigated in terms of depth of shade measurement, analysis of colorimetric properties of color and assessment of color fastness properties of henna dyed polyester fabric samples. The amount of dye absorption by fiber and the resulting depth of shade were found to increase with increasing dyeing temperature. In case of colorfastness properties, all dyed substrates demonstrated excellent fastness ratings against washing, rubbing and perspiration with little to no deterioration of color. Moreover, the detailed morphological study revealed that surface structure of fiber remained unchanged after dyeing at an elevated temperature and pressure. So, the findings suggest that dyeing of polyester fiber with henna dye without any metallic mordants is a promising approach to get the desired dyeing performance alongside opening up an avenue for eco-friendly dyeing.

Tribological Behaviors of Polymer-Based Hybrid Nanocomposite Brake Pad

Although extensive improvement has been done on brake pad for vehicles, most recent materials used still encounter wear rate, friction, stopping distance, and time deficiencies. In this regards, this study developed a polymer-based nanocomposite brake pad. Here, a combination of carbon-based materials, including those at a nanoscale, was used to produce the brake pad. Tribological performance, such as friction coefficient, wear rate, and stopping distances of developed brake pad were investigated using an inertial dynamometer. The results revealed that the stopping distances, the coefficient of friction (CoF), and wear rate vary with the brake pad formation and velocity. The micrographs show changes in the structural formation after the incorporation of carbon-based fillers. It also shows smooth surface structure and uniform dispersion of the carbon fiber. The smooth surface of the worn brake pad is an indicative of a tougher structure. Hence, it was deduced that the fabricated polymer-based hybrid composite had good tribological property. This improved property is suggestive of materials that may be successfully used for brake pad application.