Mechanical properties of hybrid fiber reinforced coral aggregate seawater concrete based on scanning electron microscopy (SEM)

To investigate the antimicrobial sports fabrics with good durability, silver ions antibacterial polyurethane fiber (Ag+PUF), chitosan/silver ions antimicrobial polyurethane fiber (CS/Ag+PUF) and quaternary ammonium salts/silver ions polyurethane fiber (QAS/Ag+PUF) were prepared. To protect the main body of antibacterial polyurethane fibers (ABPUFs) from oxidative discoloration under the influence of Ag+, the antimicrobial agent was first assembled with α-ZrP and then spun after being mixed into a polyurethane solution. In addition, nine fabric samples with different ABPUF contents (7%, 8%, 9%, 17%, 18%, and 19%) were prepared. The antibacterial properties of fibers and fabrics of Ag+PUF, CS/Ag+PUF, and QAS/Ag+PUF were characterized comprehensively and the relationship between the intrinsic antimicrobial properties of fibers and their chemical structure was demonstrated by scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis. In addition, the mechanical properties of the fibers and air and moisture permeability of the fabrics were tested. The inhibition rates against Escherichia coli and Staphylococcus aureus of ABPUF and its fabrics exceeded 99.99%. ABPUF maintained an antimicrobial rate of over 98% after soaking in acetic acid solution at pH 3, 95°C for 45 min. It was demonstrated that the antibacterial rate of the fabrics prepared with Ag+PUF, CS/Ag+PUF, and QAS/Ag+PUF was reduced by 0.24–5.4% after 2000 rubbing revolutions and by 6.99–40.47% after laundering 50 times. SEM, FTIR spectroscopy, XRD, and DSC analysis confirmed the presence of antimicrobial agents in the fibers. Mechanical properties proved that the elongation at break of ABPUF was 12.6%, 2.4%, and 1.5% less than that of PUF, respectively. In summary, ABPUF maintained excellent antimicrobial properties and durability and could be used in sports fabrics. A fuzzy mathematics comprehensive evaluation indicated that the comprehensive performance of fabric prepared by 44.4 dtex Ag + PUF with 2 + 2 mesh structure is the best.

In this paper, early research on the structure and properties of coir fibres has been critically reviewed. Gaps in the scientific information on the structure and properties of coir fibre have been identified. Attempts made to fill some of these gaps include the evaluation of mechanical properties (as functions of the retting process, fibre diameter and gauge lengths of fibre, as well as of the strain rates) and fracture mechanisms using optical and scanning electron microscopy. The deformation mechanism of coir fibre resulting in certain observed properties has been discussed with the existing knowledge of the structure of plant fibres as a basis. It is concluded that more refined models need to be developed for explaining the observed mechanical properties of coir fibres. Some of the suggestions for further work include relating properties of fibres to factors like the chemical composition of the fibre and the size and number of cells, size of lumen, variation in micro-fibril angle within each cell and between different cells of the same fibre, and understanding the deformation of the whole fibre in terms of deformation of individual micro-components. Further work is required on the effects of mechanical, thermal and thermomechanical, chemical treatments to modify the structure and mechanical properties of these fibres in such a way as to make them more suitable as reinforcements in polymer, clay and cement matrices.

Ultrahigh molecular weight polyethylene (UHMWPE) fibers exhibit excellent mechanical property, but their low surface activity limits the application in many fields. In this work, an efficient method was used to improve the surface activity and adhesion property of UHMWPE fibers. The amine functionalized UHMWPE fibers were prepared by the combination of bio‐inspired polydopamine (PDA) and grafted hexamethylene diamine (HMDA). The chemical structure of UHMWPE fibers was characterized by X‐ray photoelectron spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy. The surface morphologies and mechanical property of the fibers were investigated by scanning electron microscopy and tensile testing respectively. In addition, a single‐fiber pull‐out test was carried out to investigate the adhesion property of the fibers with epoxy resin matrix. The results showed that PDA was coated on the surface of UHMWPE fibers and then HMDA was successfully grafted on the PDA layers. The excellent mechanical property of UHMWPE fibers had no obvious change. Compared with the pristine UHMWPE fibers, the interfacial shear strength of the PDA coated UHMWPE fibers with the epoxy resin matrix improved by 28.3%, while the IFSS of the HMDA grafted UHMWPE fibers had an increase of 82.7%. Copyright © 2017 John Wiley & Sons, Ltd.

In this research, 9 series of ramie fibers were treated under low-temperature plasma with diverse output powers and treatment times. By analysis of the surface energy and adhesion power with epoxy resin, 3 groups as well as control group were chosen as reinforced fibers of composites. The influences of these parameters on the ramie fiber and its composites such as topography and mechanical properties were tested by scanning electron microscopy (SEM), atomic force microscopy (AFM), tensile property and fragmentation test of single-fiber composites. Contact angle and surface free energy results indicated that with the increased treatment times and output powers, surface energy and adhesion work with epoxy resin improved. Compared with the untreated fibers, surface energy and adhesion work with epoxy resin grew 124.5 and 59.1% after 3 min-200 w treatment. SEM and AFM showed low temperature plasma treatment etched the surface of ramie fiber to enhance the coherence between fiber and resin, consequently fiber was not easy to pull-out. After 3 min-200 w treatment, tensile strength of ramie fiber was 253.8 MPa, it had about 30.5% more than that of untreated fiber reinforced composite. Interface shear stress was complicated which was affected by properties of fiber, resin and interface. Fragmentation test showed biggest interface shear stress achieved 17.2 MPa, which represented a 54.0% increase over untreated fiber reinforced composites.

A large amount of sunflower production is carried out in our country. The 2,500,000 tons of sunflower stalks that appeared after production pose a problem for our farmer. In order to clean up this environmental problem from the field, sunflower stalks are destroyed by burning to warm up in winter, broken down and mixed into the soil, or burned after harvesting. It is thought that by obtaining qualified, ecological and naturally decomposing sunflower fiber from the stem of the sunflower plant, which is an agricultural waste, it can increase the added value of agricultural products and contribute to the protection of the environment. In this study, the anatomical characteristics of the stem of the sunflower plant were determined, and natural lignocellulosic fibers were obtained from the sunflower stem by retting and decortication methods (fresh stem, dried stem). Various physical, chemical and mechanical properties of these fibers have been measured. For this purpose, FTIR (Fourier Transform Infrared Spectroscopy) analysis, XRD (X-Ray Diffractometer) analysis and SEM (Scanning Electron Microscope) analysis were applied to the fibers obtained by different methods. Thermal analyses were performed by TG-DTA (Thermogravimetric) analysis. In addition, fiber strength, fiber fineness, fiber length and color measurements were made. The chemical content of the obtained fibers (pectin, lignin, cellulose, hemicellulose) was determined. The properties of the fibers were compared using the obtained data. As a result of the study, it has been seen that the characteristic properties of the sunflower fibers obtained by the retting method are better. It has been determined that the elemental, thermal and crystal structures of the fibers obtained by different methods are similar. It was concluded that sunflower fiber will not be spun as a yarn, but can be used as a natural polymeric composite reinforcement material.

The UV short-wavelength/infrared excitable dual-wavelength fluorescent anti-counterfeiting polypropylene (PP) fibers were spun by the traditional melt spinning process. The effects of pH value, temperature, and solvents on the structure and properties of fibers were investigated by means of tensile tester, fluorescence spectrometer and scanning electron microscope (SEM), respectively. The results showed that the fibers could emit red light under the excitation of 254 nm wavelength UV light and emit green light under the excitation of 980 nm wavelength infrared light, which show the double anti-counterfeiting effects. The dual-wavelength fluorescent fibers showed stable mechanical properties in acid and alkali resistance, whereas the fluorescence properties of fibers decreased with the increase of processing time in acid and alkali solutions. With the extension of high temperature treatment time, the mechanical properties of fibers decreased slightly and tended to be stable, while the fluorescence performance of fibers decreased gradually. The influences of different organic solvents on the properties of fluorescent fibers were different, and the fibers showed relatively good solvent resistance.

Unidirectional isora fibre reinforced epoxy composites were prepared by compression moulding. Isora is a natural bast fibre separated from Helicteres isora plant by retting process. The effect of alkali treatment on the properties of the fibre was studied by scanning electron microscopy (SEM), IR, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Mechanical properties such as tensile strength, Young's modulus, flexural strength, flexural modulus and impact strength of the composites containing untreated and alkali treated fibres have been studied as a function of fibre loading. The optimum fibre loading for tensile properties of the untreated fibre composite was found to be 49% by volume and for flexural properties the loading was optimised at ∼45%. Impact strength of the composite increased with increase in fibre loading and remained constant at a fibre loading of 54·5%. Alkali treated fibre composite showed improved thermal and mechanical properties compared to untreated fibre composite. From dynamic mechanical analysis (DMA) studies it was observed that the alkali treated fibre composites have higher E' and low tan δ maximum values compared to untreated fibre composites. From swelling studies in methyl ethyl ketone it was observed that the mole percentage of uptake of the solvent by the treated fibre composites is less than that by the untreated fibre composites. From these results it can be concluded that in composites containing alkalised fibres there is enhanced interfacial adhesion between the fibre and the matrix leading to better properties, compared to untreated fibre composites.

The aims of this study were to investigate the intercalation of polymer chains with organoclays and improve the thermo-mechanical properties of poly(butylene terephthalate) (PBT) hybrids by comparing PBT hybrids synthesized using two different organoclays. The organoclays; dodecyltriphenylphosphonium-montmorillonite (C12PPh-MMT) and dodecyltriphenylphosphonium-mica (C12PPh-Mica), were used to fabricate the PBT hybrid fibers. Variations in the properties of the hybrid fibers with the organoclays within the polymer matrix, as well as the draw ratio (DR), are discussed. The thermo-mechanical properties and morphologies of the PBT hybrid fibers were characterized using differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, electron microscopy and mechanical tensile properties analysis. The nanostructures of the hybrid fibers were determined using both scanning and transmission electron microscopies, which showed some of the clay layers to be well dispersed within the matrix polymer, although some clustered or agglomerated particles were also detected. The thermal properties of the hybrid fibers were found to be better than those of the pure PBT fibers at a DR = 1. The tensile mechanical properties of the C12PPh-MMT hybrid fibers were found to worsen with increasing DR. However, the initial moduli of the C12PPh-Mica hybrid fibers were found to slightly increase on increasing the DR from 1 to 18.

In order to explore the influence of basalt‐polypropylene hybrid fiber on the static mechanical properties and dynamic compression properties of fly‐ash concrete, 16 groups of basalt‐polypropylene hybrid fiber fly‐ash concrete (HBPC) and 1 group of benchmark concrete were designed and prepared. The slump, static compressive strength, static splitting tensile strength, and dynamic compressive performance tests were tested. At the same time, the mechanism of the mechanical properties of hybrid fiber reinforced fly‐ash concrete was analyzed by means of scanning electron microscopy (SEM). The results show that the failure of the benchmark concrete is mainly brittle failure. Compared with the benchmark concrete, the static compressive strength and splitting tensile strength of HBPC are significantly enhanced. Basalt‐polypropylene hybrid fiber, polypropylene fiber, and basalt fiber, are extremely significant factors affecting the slump, static compressive strength, and static splitting tensile strength of HBPC, respectively. The peak stress of the benchmark concrete and HBPC increases with the increase of the loading air pressure, showing a certain strain rate effect. SEM shows that the fibers have good dispersibility in the concrete and good adhesion with the concrete matrix interface, but excessive fibers will cause fiber agglomeration, which increases the internal defects of HBPC.

In recent years, researchers and scientists are facing problems in terms of environmental imbalance and global warming owing to numerous use of composite materials prepared by synthetic fibers and petrochemical polymers. Hence, an increasing attention has been devoted to the research and development of polymer composites reinforced with the natural fibers. The natural fibers are the most suitable alternative of synthetic fibers due to their biodegradability, eco-friendliness and acceptable mechanical properties. The natural fibers are attracting the researchers and scientists to exploit their properties by amalgamating them with the polymer. The properties of natural fiber reinforced polymer composites mainly depend upon various factors such as properties of fibers and matrices, fiber loading percentage, size and orientation of fibers, stacking sequences, degree of interfacial bonding, fiber surface treatments, hybridization and incorporation of additives and coupling agents. Tensile and flexural tests are the most important investigations to predict the applications of the materials. A good number of research has been carried out on tensile and flexural properties of natural fiber reinforced polymer composites. In this paper, a review on tensile and flexural properties of natural fiber reinforced polymer composites in terms of effects of fiber weight fraction, geometry, surface treatments, orientations and hybridization is presented. Moreover, recent applications of natural fiber reinforced polymer composites are also presented in this study.

Nowadays, kenaf fibers are becoming extensively used as natural reinforcements for polymeric composites. The mechanical properties of the fibers are the most influential elements on the characteristics of the composites. In the current work, tensile property of kenaf fiber was studied at different aging conditions (immersed in water, salt water, diesel, and engine oil). The tensile property of the fiber was tested in two different techniques as single fiber and bundle (20–55 fibers). Surface morphology of the fibers, before and after aging, was observed using scanning electron microscopy. The results showed that engine oil highly influenced the mechanical properties of the fiber compared to the other solutions. A drop in the strength was about 70% for both untreated and treated fibers immersed in diesel solution followed by diesel, and then water. The reduction in tensile strength by salt–water solutions was the least, at about 27.16% for untreated fibers. The damage on the fiber aged in salt water was less than the damages observed on the aged fibers in other solutions.

In this work, the two-stage process for producing polyimide fiber from polyamic acid (PAA) by wet spinning was used. Polyimide fibers were obtained by thermal and chemical imidization. The effect of the imidization method (chemical and thermal) on morphology, chemical structure, thermal stability and mechanical properties of polyimide fibers was investigated. A number of research methods were used in the work, such as Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calometry (DSC), thermogravimetric analysis (TGA) and determination of strength characteristics.

Molecular and Structural Changes in Induced-Brain Stroke Tissue Using FTIR Imaging Spectroscopy, Scanning Electron and Atomic Force Microscopy

Typical polypropylene fibers for use in light nonwoven fabrics were produced in a full scale compact‐spinning line. Molecular weight distribution (MWD), extrusion temperature, draw‐down ratio, and draw ratio were varied. The fibers were thermally bonded (welded) into nonwoven fabrics, at different bonding temperatures, using a pilot calender line. The tensile properties of the fabrics are influenced by the MWD and the processing conditions of the fibers, and the effects of these fiber parameters increase with increasing bonding temperature. The fabric strength increases with increasing Mw/Mn, decreasing draw ratio, and increasing extrusion temperature, while in all these cases the fiber strength generally follows the opposite trend. Furthermore, the fabric strength, as well as the fiber strength, have a maximum as a function of draw‐down ratio. The tensile properties of the fabrics seem to be governed by the bonding properties of the constituent fibers, not the fiber strength per se. Bond characteristics are discussed in terms of skin‐core structures. Some details of the macroscopic fracture mechanisms of fabrics were revealed by scanning electron microscopy and the shape of load‐elongation curves. © 1995 John Wiley & Sons, Inc.

The properties of polycrystalline optical fibers produced by extruding crystals of AgCl1−x Brx(x = 0.5–0.8) solid solutions are studied by optical microscopy, scanning electron microscopy, microstructural analysis, and x-ray microanalysis. The results demonstrate for the first time that the arrangement of polycrystalline regions and recrystallized single-crystal blocks 0.03-–0.10 and 2–5 µm in size, respectively, possesses three- or fourfold symmetry or a mirror plane m, depending on the crystallographic orientation of the parent crystal (cubic symmetry). The effect of the structural properties of the parent crystal on the properties of the fibers is discussed.