Mechanical Properties Of Fibers Research Articles

Carbon fiber surface nano-modification and enhanced mechanical properties of fiber reinforced cementitious composites

It has been widely recognized that fiber–matrix interface has great significance on the performance of fiber-reinforced cementitious composites. In this research, an effective fiber modification method is proposed and its enhanced mechanical properties are observed. Through the condensation and polymerization of the tetraethyl orthosilicate under alkaline conditions, a thin SiO2 layer was formed on carbon fiber surface, which can react with Ca(OH)2 thus form calcium silicate hydrate to condense the fiber–matrix interface. In this paper, nano-SiO2 modified carbon fibers are produced and the mechanical properties of modified carbon fiber reinforced cementitious composites are investigated. Modified material exhibited 24.7% enhancement in flexural strength and up to 25.1% enhancement in tensile strength with the fiber volume fraction of 0.5%. Better post-crack behavior and toughness properties were also estimated, which were attributed to nano-modification strengthening the ITZ through the reaction of surface nano-SiO2 with Ca(OH)2 resulting in much more amount of CSH gel and a denser microstructure of fiber–matrix interface. The microstructure of denser interface and porosity can be found through SEM and BSEM analysis. The porosity on the observation surface of interface transition zone of unmodified fiber and modified fiber was 4.03% and 2.43%, respectively. The change of chemical elements in the interface transition zone was analyzed by line scanning, and the Ca/Si of the modified carbon fiber was significantly lower than that of the unmodified carbon fiber.

Tyrosine's Unique Role in the Hierarchical Assembly of Recombinant Spider Silk Proteins: From Spinning Dope to Fibers.

Producing recombinant spider silk fibers that exhibit mechanical properties approaching native spider silk is highly dependent on the constitution of the spinning dope. Previously published work has shown that recombinant spider silk fibers spun from dopes with phosphate-induced pre-assembly (biomimetic dopes) display a toughness approaching native spider silks far exceeding the mechanical properties of fibers spun from dopes without pre-assembly (classical dopes). Dynamic light scattering experiments comparing the two dopes reveal that biomimetic dope displays a systematic increase in assembly size over time, while light microscopy indicates liquid-liquid-phase separation (LLPS) as evidenced by the formation of micron-scale liquid droplets. Solution nuclear magnetic resonance (NMR) shows that the structural state in classical and biomimetic dopes displays a general random coil conformation in both cases; however, some subtle but distinct differences are observed, including a more ordered state for the biomimetic dope and small chemical shift perturbations indicating differences in hydrogen bonding of the protein in the different dopes with notable changes occurring for Tyr residues. Solid-state NMR demonstrates that the final wet-spun fibers from the two dopes display no structural differences of the poly(Ala) stretches, but biomimetic fibers display a significant difference in Tyr ring packing in non-β-sheet, disordered helical domains that can be traced back to differences in dope preparations. It is concluded that phosphate pre-orders the recombinant silk protein in biomimetic dopes resulting in LLPS and fibers that exhibit vastly improved toughness that could be due to aromatic ring packing differences in non-β-sheet domains that contain Tyr.

Effect of Fiber Modification on Pineapple Leaf Fiber's Mechanical Properties and Interfacial Adhesion

Effect of Fiber Modification on Pineapple Leaf Fiber's Mechanical Properties and Interfacial Adhesion

The evolution of carbon fiber elements and their effects on fiber mechanical properties from molecular dynamics

Carbon fibers are ideal light-weight materials for aerospace applications due to their properties such as high strength, high modulus. As a result, there are significant efforts aimed at studying the theory of fiber structure and fabrication methods. The mechanical performance of carbon fibers can be controlled by the interaction of many complex factors, one of them being the element characteristic. Here, we use the molecular dynamics simulations to predict the evolution of non-carbon elements during heating and their responses to mechanical behavior. Particularly, the possible structures of N, O and Si are comprehensively studied. It is observed that Si results in the formation of CNSi chains and OH residues, which hinders the improvement of the strength of the carbon fibers. The oxygen-containing groups of the terminal ester can increase the content of adjacent chain structures that preferentially participate in carbonization. The O groups of hydroxypyridine lead to significantly lower carbonization onset temperature of polyacrylonitrile (PAN) via the pathway for H2O elimination, while the reaction rate of the H2O molecules is relevant to the PAN chain length distribution and local density. Interestingly, in the case of oxygen-modified carbon fibers, the Young’s modulus is predominantly affected. The release temperature of N, ranked from lowest to highest, is given by the chain-end CN group > hydrogenated-CN > unhydrogenated-CN, and the “transfer hopping” effect of the N element on the activated carbon chains contributes to carbon rearrangement during carbonization. The modified carbon ring structure comprising of 1.0–3.0 wt% N element is beneficial factor for conferring high tensile strength and large elongation to the carbon fibers. Our results provide valuable insights for the preparation and screening of high-performance carbon fibers from an elemental perspective, which can pave the way for a systematic framework for optimizing their performance.

Evaluation of the density, mechanical, thermal and chemical properties of babassu fibers (Attalea speciosa.) for potential composite reinforcement

The properties of babassu (Attalea speciosa.) fiber was for the first time investigated for potential engineering application such as reinforcement for matrix composites. The diameter distribution of babassu fibers was analyzed and found to be associated with significant variation in fiber density and mechanical properties. Additionally, thermogravimetric and Fourier transform infrared spectrometry (FTIR) analyses were performed. The studied Weibull statistical method was used to analyze the acquired data. The surface morphology of the fibers was studied by scanning electron microscopy. From the diameter ranges, it was possible to confirm that the thinner fibers have higher values of density and mechanical properties, which was attributed to their lower presence of defects. The diameter range was found between of 0.18 and 0.47 mm, and the corresponding densities were 0.79 and 0.27 g/cm³ respectively. Furthermore, the maximum tensile strength found was 100.76 MPa with an elastic modulus of 6.33 GPa and an elongation of 2.98%. Thermogravimetric analyses revealed a three-step mass loss, the main one being the second where the fiber loses 69% of the mass at a temperature of 382 °C. The FTIR analysis showed a similarity with the bands generally found in the literature for natural lignocellulosic fibers.

Characterization of Electrospun Polysuccinimide-Dopamine Conjugates and Effect on Cell Viability and Uptake.

Biocompatible nanofibrous systems made by electrospinning have been studied widely for pharmaceutical applications since they have a high specific surface and the capability to make the entrapped drug molecule amorphous, which increases bioavailability. By covalently conjugating drugs onto polymers, the degradation of the drug as well as the fast clearance from the circulation can be avoided. Although covalent polymer-drug conjugates have a lot of advantages, there is a lack of research focusing on their nano-formulation by electrospinning. In this study, polysuccinimide (PSI) based electrospun fibrous meshes conjugated with dopamine (DA) are prepared. Fiber diameter, mechanical properties, dissolution kinetics and membrane permeability are thoroughly investigated, as these are crucial for drug delivery and implantation. Dopamine release kinetics prove the prolonged release that influenced the viability and morphology of periodontal ligament stem cells (PDLSCs) and SH-SY5Y cells. The presence of dopamine receptors on both cell types is also demonstrated and the uptake of the conjugates is measured. According to flow cytometry analysis, the conjugates are internalized by both cell types, which is influenced by the chemical structure and physical properties. In conclusion, electrospinning of PSI-DA conjugates alters release kinetics, meanwhile, conjugated dopamine can play a key role in cellular uptake.

Effect of nanosilica on fiber pullout behavior and mechanical properties of strain hardening ultra-high performance concrete

The bond properties between the fiber and matrix are a critical factor that affects the tensile properties and toughness of fiber-reinforced cementitious composites. This research aims to provide an effective method to improve the tensile properties of ultra-high performance concrete (UHPC) with strain hardening characteristics. The compressive, flexural, and tensile behavior was measured on UHPC with two geometric configurations of steel fibers and four nanosilica (nano-SiO2) mass fractions (0/1/3/5 wt% substitution rate of cement mass). The pull-out load-slip responses of steel fibers were also captured. In particular, determined the effect of fiber slip response on tensile properties of UHPC, then calculate elastic, strain hardening, and softening tensile parameters. Furthermore, the SEM, EDS, MIP, and XRD tests were used to reveal the enhancement mechanism of interfacial bonding performance and mechanical properties. The results show that the compressive and flexural strength peaks at 3 wt% of nanosilica, owing to nanosilica effectively ameliorating the pore structure and promoting the hydration process of the matrix. While the fiber pullout behavior and tensile properties show better performance at 5 wt% associated with increased hydration products attached to the fiber surface and more severe scratches after being pulled out. Notably, the addition of nanosilica endows strain hardening properties to UHPC containing straight fibers as well as increases the tensile toughness of UHPC containing hooked fibers due to the reinforcement of the matrix tunnel surrounding the steel fibers.

Relation between injection molding conditions, fiber length and mechanical properties for highly reinforced long fiber polypropylene

AbstractA complete study on the relation between the injection molding parameters and the resulting fiber length, orientation and mechanical properties is presented for highly reinforced long fiber thermoplastic (LFT) polypropylene (PP). It has been found that the longest fibers obtained are the ones processed with the lowest backpressure and the highest screw speed. The backpressure gains importance over screw speed when the amount of glass fiber reinforcement increases, contrary to what was found for less reinforced thermoplastics. The injection speed does not influence the fiber breakage phenomena, while it has great importance in fiber orientation and thus on the tensile strength, especially when the weight fiber average length is below 1000 μm. When this average is over 1000 μm, fibers begin to weave a mesh that thickens the core region and hinds its orientation, reducing the tensile strength but improving impact resistance.

The study of correlations among the process condition, structure and property for poly(l-lactide) fibers

This article focus on derive the process-structure-property relationship of Poly(l-lactide) (PLLA) fibers prepared by two-step melt spinning process. The spinning temperature, spinning rate, drawing temperature as well as draw ratio were studied to analyze the influence of process variables on the structure and properties of PLLA fibers. It suggests that the crystallinity, lamellar orientation structure and mechanical properties of fibers are dependent on the spinning conditions, including melt-spinning and hot-drawing process. An approximate linear correlation resulted between the orientation degree and tensile strength of PLLA fibers, which means that the oriented structure plays a dominant role to enhance PLLA fibers. PLLA fibers with high performance of 499 MPa and 5.30 GPa in tensile strength and Young’s modulus separately have been realized by the selected spinning parameters. The results provide a theoretical direction for enhancing PLLA fibers by adjusting the structure characteristic via modifying the spinning parameters.

Preparation and characterization of graphene antibacterial phase change energy storage viscose fibers

In this work, viscose fiber with antibacterial and phase change energy storage was made by microcapsule technology and wet spinning. Graphene oxide was used to enhance the thermal conductivity and antimicrobial properties. The heat preservation performance of graphene antibacterial phase change energy storage viscose fiber was determined by flat type fabric temperature protector and differential scanning calorimetry. The result of heat preservation test shows that the fiber has a good heat preservation property The antibacterial property, far-infrared property, mechanical properties, and the structures were also characterized. The enthalpy of exothermic & endothermic phase transition reached about 10 mJ/mg. According to the result of antibacterial test, the fiber had good antibacterial properties. The distribution of phase change microcapsules and graphene in fibers was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The strength and elongation of antibacterial phase change viscose fiber were found suitable for underwear garments fabrics and filling storage sheet. Combined with the electron microscope photograph and strength test results, the addition of graphene and phase change microcapsules has little effect on the mechanical properties of fibers, and can be used for industrial production.

The polymer and materials science of the bacterial fimbriae Caf1.

Fimbriae are long filamentous polymeric protein structures located upon the surface of bacteria. Often implicated in pathogenicity, the biosynthesis and function of fimbriae has been a productive topic of study for many decades. Evolutionary pressures have ensured that fimbriae possess unique structural and mechanical properties which are advantageous to bacteria. These properties are also difficult to engineer with well-known synthetic and natural fibres, and this has raised an intriguing question: can we exploit the unique properties of bacterial fimbriae in useful ways? Initial work has set out to explore this question by using Capsular antigen fragment 1 (Caf1), a fimbriae expressed naturally by Yersina pestis. These fibres have evolved to 'shield' the bacterium from the immune system of an infected host, and thus are rather bioinert in nature. Caf1 is, however, very amenable to structural mutagenesis which allows the incorporation of useful bioactive functions and the modulation of the fibre's mechanical properties. Its high-yielding recombinant synthesis also ensures plentiful quantities of polymer are available to drive development. These advantageous features make Caf1 an archetype for the development of new polymers and materials based upon bacterial fimbriae. Here, we cover recent advances in this new field, and look to future possibilities of this promising biopolymer.

Experimental study on strength behaviour of concrete reinforced with natural fibers

In this study, concrete with an addition of natural fibers combination such as sisal, jute and pineapple fibers are added to investigate the characteristics of concrete as trend of fiber usage is increasing. The ratio of water to binder was set to 0.4. Combination of fibers like sisal and pineapple, pineapple and jute, and jute and sisal were added in percentages 0.25 %, 0.5 % and 0.75 % of volume and with lengths of 22 mm and 30 mm.The objective of this study was to explore if natural fibers like sisal, jute, and pineapple in combination can be used to increase structural concrete's mechanical properties of fiber reinforced concrete. Concrete with a fiber combination of sisal and pineapple of 22 mm length at 0.25 %, have the better performance than other combinations of natural fibers.

A comprehensive review of natural fiber reinforced composite and their modern application

The industrial sector heavily depends on materials. According to the Kyoto Protocol, enterprises are becoming more and more interested in obtaining carbon credits through lowering air pollution. Therefore, green composite materials must be used in place of conventional materials to complete the carbon credit. Natural fiber-reinforced composite materials are now widely utilized in contemporary industrial sectors for example sports, automotive, medicine, aerospace, electronics, food packaging, and energy storage where engineered heterogeneity has been developed and utilized to achieve specific engineering functions. Because of its exceptional mix of thermal, mechanical, and dielectric qualities as well as environmental benefits including renewability and biodegradability, natural cellulosic fiber composite materials are becoming more and more popular for a variety of industrial applications. Natural cellulosic fiber-reinforced composite mechanical and thermal properties as well as for natural fibers mechanical properties and thermal properties also interpreted in this article.

Improvement of Natural Fiber Mechanical Properties for Structural Polymer Composites

Improvement of Natural Fiber Mechanical Properties for Structural Polymer Composites

Mechanical Properties and Waste Management Approaches of Banana in India

Abstract: Around 27% of the contribution to the world's banana production is done by India only. This directly leads to an increase in waste loss. Despite its tremendous utilization, nutritional & health benefits, and mechanical properties of fibres which allows the growth of the economy in the country, the problem of waste management in India is big. Usually, the leaves, pseudostems, rachis and banana peel are the major solid waste-loss of bananas which corresponds to its maintenance and harvesting practices. Its waste loss amounts to roughly 114 million metric tonnes worldwide, contributing to environmental issues such as the excessive emission of greenhouse gases. Thus, this review paper focuses on the the mechanical properties of pseudostem fibres which offer a significant bioresource to create a variety of high-value goods, including rope, cordage, fishing nets, mats, packaging materials, paper sheets, textile fabrics, bags, tablecloths, handicrafts, absorbent materials, and polymer composites. The research on banana fibre-reinforced composite materials is a new field of research and is still open to be explored. These composite-based fibres have a good potential to be used in various sectors like construction, automotive, machinery, etc., due to their high mechanical strength. Many advancements in the manufacturing techniques of its fibres are under process to ease the process. However, still, hand layup, compression moulding, and filament winding are the processes which are followed. Thus, this review paper focuses on the mechanical properties & utilization of banana pseudostem fibres and approaches to combat the main challenges of waste management and to provide sustainable solutions to achieve social, economic, and environmental benefits.

Effect of Inclusion of Polypropylene Fiber on Behavior of Concrete

In this paper, a comprehensive review related to the history of polypropylene fiber, its durability, dimensional stability, permeability, and eco-friendly properties were discussed. The influence of polypropylene fiber in mechanical properties like tensile, compressive and flexural strength is explored by performing a comparative analytical study concerning conventional concrete and polypropylene fiber reinforced concrete (PPFRC). The case study was carried out to know the variation in the behavior of concrete due to different aspects such as spalling, and abrasion resistance. By the proper addition of fiber content in the concrete mix it can be predicted that there might be an increase in the physical and mechanical properties of fiber, so simultaneously by varying the polypropylene fiber content from 0.5% - 2% in terms of volume, samples are tested under controlled curing conditions and the optimum polypropylene fiber content is suggested. Fibers are distributed randomly in a concrete mix; possess to increase the energy-absorption capacity of concrete and leads to a decrease in their plastic shrinkage cracks. Further investigations are highly recommended to understand more about the mechanical properties of (FRC) fiber reinforced concrete.

EFFECT OF COOLING RATE OF BASALT MELTS ON STRENGTH OF CONTINUOUS FIBER IN THE DRAWING PROCESS

The questions of optimizing the operation parameters of basalt fiber drawing with the view to raising fiber strength are considered. To find out the interdependency between mechanical properties of fibers and thermal characteristics of basalt melt in the drawing process both mathematical modeling and experimental investigations have been undertaken in this study. The accurate numerical model, which describe adequately heat transfer in the drawing process of glass fiber has been used to determine the cooling rate of a melt jet in the vitrification stage. The fiber strength is found to be proportional to the melt cooling rate which is specified completely by the initial conditions of drawing. The results provide the theoretical basis of cnoosing and regulating technological parameters in the production of basalt and glass fibers. Fiber materials of various purpose, obtained from basalt continuous fibers, have high physicochemical characteristics, which are inferior only to expensive composites based on carbon and carbidities. Basalt continuous fibers are characterized by increased strength and elastic module. By strength properties, continuous basalt fibers are compared to glass fibers, and by module
 The elasticity exceeds them. The ability to control the properties of fibers in the production of basalt fibers is an important stage in the way of improving and optimizing the technology of their production. Obtaining basalt fibers with high strength and elasticity module requires understanding of the basic factors that affect these parameters. First of all, the chemical and mineralogical composition of the raw material.

Thermal tolerance role of novel polyamine, caldopentamine, identified in fifth instar Bombyx mori.

Silkworms have limited ability to regulate their body temperature; therefore, environmental changes, such as global warming, can adversely affect their viability. Polyamines have shown protection to various organisms against heat stress. This study evaluated the qualitative and quantitative changes in heat-stressed Bombyx mori larvae polyamines. Fifth instar Bombyx mori larvae were divided into two groups; control group,reared at room temperature, i.e., 28 ± 2°C, and the heat shock group, exposed to 40°C. Dansylation of the whole worm polyaminesand subsequent thin-layer chromatography revealed the presence of components with the same Rf value as dansyl-putrescine, spermidine, and spermine. The dansyl-putrescine, spermidine, and spermine polyamines were identified by mass spectrometric analyses. After heat shock, the thin-layer chromatography of the whole-larvae tissue extracts showed qualitative and quantitative changes in dansylated polyamines. A new polyamine, caldopentamine, was identified, which showed elevated levels in heat-stressed larvae. This polyamine could play a role in helping the larvae tolerate various stress, including thermal stress. No significant changes in silk fiber's economic and mechanical properties were observed in our study. This study indicated that PA, caldopentamine, supplementation could improve heat-stress tolerance in Bombyx mori.

Effects of Different Delignification and Drying Methods on Fiber Properties of Moso Bamboo.

Bamboo has become an important kind of fibrous raw material in the world due to its fast-growing property and abundance of natural fiber. During the purification and utilization of bamboo fiber, the removal of lignin is vital and it is affected by the chemical treatment system and drying method. In this paper, the effects of three different delignification chemical systems and three drying methods (air drying, drying and freeze drying) on the physical and chemical properties of bamboo fiber were comparatively studied. The results prove that all three delignification techniques can effectively remove lignin from wood, and by utilizing peroxyformic acid and alkaline sodium sulfite, hemicellulose can be removed to a certain extent. With the selective removal of amorphous hemicellulose and lignin and the hydrolysis of cellulose molecular chains in amorphous regions, all three treatments contributed to an increase in the relative crystallinity of cellulose (ranging from 55% to 60%). Moreover, it was found that the drying methods exerted a certain influence on the mechanical properties of fiber. For instance, drying or air drying would improve the tensile strength of fiber significantly, approximately 2-3.5 times that of original bamboo fiber, and the tensile strength of the drying group reached 850-890 MPa. In addition, the alkaline sodium sulfite treatment had little effect on the thermal stability of bamboo fiber, resulting in high thermal stability of the prepared samples, and the residual mass reached 25-37%. On the contrary, the acetic acid/hydrogen peroxide method exerted great influence on the thermal stability of bamboo fiber, giving rise to a relatively poor thermal stability of prepared fibers, and the residual mass was only about 15%. Among the three drying methods, samples under air drying treatment had the highest residual mass, while those under freeze drying had the lowest. To summarize, the alkaline sodium sulfite method is more suitable for preparing bamboo fiber with higher tensile strength and thermal stability.

Fabrication of high strength and functional GO/PVA/PAN ternary composite fibers by gel spinning

Abstract Polyacrylonitrile (PAN) fiber is soft and comfortable, but its poor strength compared to other synthetic fibers has limited it wide range of applications. This study effectively improved the strength of PAN fibers by adding graphene oxide (GO) and polyvinyl alcohol (PVA) during PAN spinning. The composite fibers were prepared via gel spinning and subsequent hot drawing process. The results show that the PVA molecular chains embedded into the PAN molecular chain significantly improved the mechanical properties of the hybrid fiber. At the same time, the defect reduced the UV resistance and thermal stability of the hybrid fibers only when the PVA molecular was introduced in the PAN. Surprisingly, after the recomposition of GO in the above mixed polymer system, the interaction between the GO and matrix not only improved the mechanical properties of the fiber, but also enhanced the UV resistance and thermal stability. In addition, when the amount of GO was 0.3 wt%, the crystallinity of the GO/PVA/PAN composite fiber reached the maximum and the tensile strength was the highest. This strategic approach suggests an effective method to prepare graphene-based ternary composites fibers with high strength and novel functional characteristics.