Influence of the diameter on the mechanical property of agave fibre and their concentration on the thermomechanical properties of the Gypsum/Agave biocomposite

Hemp fiber, recognized for its eco-friendliness, wide availability, and biodegradability, stands as a renewable resource with promising applications. To fully harness its potential, it is crucial to study the relationship between chitosan concentration and both the mechanical and thermal properties of hemp fiber. Understanding these effects can provide a direction to improve the properties and functionalities of hemp fiber, which are essential for many applications, including textiles and construction and automotive materials. Chitosan is known to enhance the antimicrobial and adsorption properties of fibers by changing the chemical properties of the fiber surface. However, up to now, a very limited number of studies have focused on the exact effect of chitosan on the mechanical and thermal stability properties of hemp fibers. Here, the effect of treatment with different concentrations of chitosan solutions is investigated to enhance the properties of hemp fibers and the treated hemp fibers are characterized. It is found that chitosan solution treatment can effectively improve the various properties of hemp fibers. The chitosan treatment improved the surface roughness of hemp fibers. The tensile strength and flexibility of hemp fibers were enhanced. The CSHF-1.5% sample exhibited the highest tensile strength of 616.11 MPa and the lowest tensile modulus of 15.61 GPa. The fiber swelling rate increased to 24.73% at a chitosan solution concentration of 1.5%. The results of thermogravimetric analysis and differential scanning calorimetry analysis demonstrated the effectiveness of chitosan solution treatment in enhancing the thermal stability of hemp fibers. These findings propose a promising method for a significant modification of hemp fiber's mechanical and thermal stability.

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.

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.

Blending of cotton wastes with raw materials to produce different textile products has economically and environmentally beneficial. This study was carried out in Cotton Research Institute, Agricultural Research Center. This investigation aimed to study the impact of blending ratio on fiber, mechanical and physical yarn quality properties to find out the optimum blending ratio that achieves the optimum yarn quality properties. For this purpose, fiber properties, mechanical and physical yarn quality properties of ring spun yarns produced from cotton variety Giza95, Delta pine245 cotton variety (upland cotton) combed cotton waste of Extra Fine Giza93 and six different binary blend ratios were studied. Blended samples were spun into 36s, and 40s, carded yarns at constant twist multiplier 4 on ring spinning system. the results showed that fiber properties, Physical and mechanical properties of yarns produced from Giza95 were better than 100% upland cotton, 100% combed cotton waste and the other blended yarns.65% Giza95-35% combed waste of blended samples recorded higher fiber properties(maturity ratio, fiber length, uniformity index, fiber strength and fiber elongation) than all blended samples.Also,the same blended ratio at 36s, yarn count give better lea count product strength, yarn strength, yarn elongation, evenness, imperfections and yarn hairiness compared with all blended yarns followed by 65% combed waste - 35% Giza95.While, the lowest yarn quality properties recorded by The blended yarn of 35% Giza95-65% Delta pine245. Also, it observed that increasing proportion of G95 cotton variety in blended samples led to improve fiber, mechanical and physical yarn properties

Spiders can produce up to seven different types of silk, each with unique mechanical properties that stem from variations in the repetitive regions of spider silk proteins (spidroins). Artificial spider silk can be made from mini-spidroins in an all-aqueous-based spinning process, but the strongest fibers seldom reach more than 25% of the strength of native silk fibers. With the aim to improve the mechanical properties of silk fibers made from mini-spidroins and to understand the relationship between the protein design and the mechanical properties of the fibers, we designed 16 new spidroins, ranging from 31.7 to 59.5 kDa, that feature the globular spidroin N- and C-terminal domains, but harbor different repetitive sequences. We found that more than 50% of these constructs could be spun by extruding them into low-pH aqueous buffer and that the best fibers were produced from proteins whose repeat regions were derived from major ampullate spidroin 4 (MaSp4) and elastin. The mechanical properties differed between fiber types but did not correlate with the expected properties based on the origin of the repeats, suggesting that additional factors beyond protein design impact the properties of the fibers.

This study investigated the effects of impregnation modification via vacuum resin impregnation on physical and mechanical properties of sugar palm (Arenga pinnata) fibres. The fibre was evacuated at a constant impregnation pressure of 1000 mmHg impregnation times (0, 5, 10, 15, 20 and 25 min) with two different impregnation agents: phenol formaldehyde (PF) and unsaturated polyester (UP). A notable improvement in the physical properties of sugar palm fibres was observed after they were impregnated with PF and UP for 5 min, shown by the reduction of their moisture content (91 % and 89 %, respectively) and water absorption (43 % and 41 %, respectively) compared to the control sample. However, no significant improvement (p≤0.05) in the physical properties of fibre was observed when the impregnation time was extended (from 10 to 25 min) using both impregnation agents. As for the mechanical properties of the fibre, significant improvement was observed after they were impregnated for 5 min. The fibres impregnated with UP resulted in better fibre toughness and improved mechanical properties as shown in their higher tensile strength and elongation at break compared to the fibres impregnated with PF. Both the physical and mechanical properties showed no significant improvement (p≤0.05) after time for impregnation was extended (from 10 to 25 min) using both impregnation agents. Therefore, it can be concluded that the physical and mechanical properties of sugar palm fibre could be enhanced by impregnating the fibre with thermosetting polymer (PF and UP) for 5 min. It was shown that impregnation with unsaturated polyester (UP) showed better improvement than phenol formaldehyde (PF). In addition, this study also concluded that the unsatisfactory enhancement of the properties of sugar palm fibre even after the impregnation time was extended from 10 to 25 min was due to the use of low impregnation pressure of 1000 mmHg.

Multicellular fibres formed by Bacillus subtilis (B. subtilis) are attracting interest because of their potential application as degradable biomaterials. However, mechanical properties of individual fibres remain unknown because of their small dimensions. Herein, a new approach is developed to investigate the tensile properties of individual fibres with an average diameter of 0.7 μm and a length range of 25.7–254.3 μm. Variations in the tensile strengths of fibres are found to be the result of variable interactions among pairs of microbial cells known as septa. Using Weibull weakest-link model to study this mechanical variability, we predict the length effect of the sample. Moreover, the mechanical properties of fibres are found to depend highly on relative humidity (RH), with a brittle–ductile transition occurring around RH = 45%. The elastic modulus is 5.8 GPa in the brittle state, while decreases to 62.2 MPa in the ductile state. The properties of fibres are investigated by using a spring model (RH < 45%) for its elastic behaviour, and the Kelvin–Voigt model (RH > 45%) for the time-dependent response. Loading-unloading experiments and numerical calculations demonstrate that necking instability comes from structural changes (septa) and viscoelasticity dominates the deformation of fibres at high RH.

Composite Lyocell fibers were successfully prepared from cotton linter pulp and bamboo hemicelluloses with N-methyl-morpholine-N-oxide as a solvent. The viscosity of the spinning solutions, as well as the structural and mechanical properties of the composite fibers were investigated to understand the effect of hemicelluloses on the dissolution process and the properties of fibers. The addition of hemicelluloses raised the concentration of spinning dopes and reduced the average molecular weight of raw materials, leading to the increase and then decrease of the viscosity of solution. The crystal and morphological structure of the fibers were slightly influenced by the presence of hemicelluloses, while the tensile strength and modulus of the fibers were improved by adding appropriate amount of hemicelluloses. Moreover, the distribution of hemicelluloses in the solution and composite fiber were proposed to illustrate this regulating effect. This study provided an alternate way to improve the properties of Lyocell fibers and enlarge the utilization of hemicelluloses.

Piezoelectric ceramic fibers are widely used in piezocomposite devices. The various methods that are used to draw ceramic fibers differ in the way the fiber form is obtained, which in return closely affects the density, uniformity and the properties of the fibers that are obtained at the end. In this study, the processing‐property relationship in the piezoceramic fibers drawn using the alginate gelation method is investigated, with a focus on the mechanical and electrical properties of individual fibers. Fibers with a Weibull strength of 65.3 MPa, remanent polarization of 22 μC/cm2 and a total bipolar field induced strain of 0.25% under an electric field of 2.5 kV/mm, piezoelectric coefficient of 300 pm/V and dielectric constant of 3323 were produced. 1‐3 piezocomposite devices prepared from these fibers had a 6 dB higher free‐field voltage sensitivity and a 50% wider bandwidth compared to a solid disk transducer of the same dimensions.

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.

We investigate the potential of Brillouin Light Scattering (BLS) Microspectroscopy for fast non-invasive all-optical assessment of the mechanical properties of viscose fibers and bleached softwood pulp. Using an optimized Brillouin spectrometer, we demonstrate fast spatial mapping of the complex longitudinal modulus over extended areas (> 100 µm). Our results reveal that while the softwood pulp has a relatively uniform moduli, the viscous fibers have significant spatial heterogeneous in the moduli. Specifically, the viscose fibers exhibited a regular pattern of increasing and decreasing modulus normal to the fiber axis. The potential influence of a locally changing refractive index is investigated by holographic phase microscopy and ruled out. We discuss our results in light of the anisotropic mechanical properties of the fibers and are able to estimate the relative difference between the modulus along the fiber axis and that perpendicular to it. Results are presented alongside reference measurements of the quasi-static mechanical properties transverse to the fiber axes obtained using AFM-nanoindentation which reveal a similar trend, hinting at the potential usefulness of BLS for mechanical characterization applications. However, more detailed investigations are called for to uncover all the factors influencing the measured high-frequency BLS modulus and its significance in relation to physical properties of the fiber that may be of practical interest.

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 &amp; Sons, Ltd.

Effects of the Ar flow rate on the composition, structure, and properties of near-stoichiometric SiC fibres that were annealed at 1600°C

The alkaline treatment condition plays a crucial role in governing the ultimate properties of flax fibers. In this study, flax fibers were modified with mild alkalization and severe mercerization conditions to give fundamental insight into how the molecular-scale changes in cell wall fine structure and cellulose supramolecular structure can affect the macroscopic properties of fibers. SEM, FTIR, XRD, TGA, and DSC techniques were employed to characterize the variations in morphology, composition, crystalline structure, and thermal properties of fibers. Also, tensile tests evaluated their reinforcing performance in polypropylene-based composites. The results indicated that alkalization in 5% (w/v) NaOH solution preserved the tensile properties of fibers, shifted their thermal decomposition temperature from 198 to 254°C, and effectively decreased their moisture absorption content by 18%. The improvements primarily originate from the partial removal of noncellulosic constituents and promoted crystallinity of native cellulose Iβ structure. However, mercerization in 20% (w/v) solution significantly reduced the rigidity of fibers in the longitudinal direction. Furthermore, it decreased the moisture absorption only by 6% and shifted the thermal degradation to 275°C. The excessive elimination of noncellulosic constituents and the polymorphic transformation, which led to a weaker hydrogen bonding network in the cellulose II region, accounts for these changes.

This investigation was carried out at Plant Production Department, Faculty of Agriculture (Saba-Basha), Alexandria University, Egypt and at Cotton Research Institute, ARC, Giza, Egypt, to study the effect of cotton variety and lint grade on fiber and yarn mechanical properties during 2018 season. Two commercial Egyptian cotton varieties, G. barbadense namely: Giza 87 and Giza 96 as Extra-long staple (ELS) were used. Three lint cotton grades i.e., Good to Fully Good (G/FG), Good (G) and Fully Good Fair to Good (FGF/G) were used for each variety. Fibers were processed to combed yarns Ne 80. The H.V.I. classing 1000, Pressely, Stelometer and Cotton Classifying System (CCS) instruments were used to determine the physical and mechanical fiber properties.The grading system in Egypt depends upon the experience of the classer to determine grade and quality of the raw cotton according to the official grade standard of each cotton variety. The results indicated that classer's was highly significant correlated with all instrumentally measured traits (positively or negatively). The Extra-long cotton varieties had a highly significant effect for fiber properties The highest mean value of micronaire reading (3.51), maturity index (87%) , fiber length (UHML) (35.80 mm) , fiber strength (44.1 g/tex), fiber elongation(5.4 %), spinning constant index (222), reflectance degree (75.7) and trash count (112) were recorded for the Egyptian cotton variety Giza 96 .As for the lint cotton grades effect , it could be concluded that the highest lint cotton grade Good to Fully Good (G/FG) recorded the best of all fiber properties which as high value of micronaire reading , maturity index , fiber length(UHML), uniformity index, fiber strength, spinning constant index and less of short fiber index , yellowness degree and trash count vice versa. Cotton varieties (V) had highly significant differed for mechanical cotton properties measured by three instruments( HVI , Stelometer and Pressley) i.e. fiber strength and fiber elongation the highest mean values of the fiber strength ( 44.4 g / tex) , was attained by the cotton variety Giza 96. Whereas the lowest mean values (43.2 g/tex) and (4.8 %) of the fiber elongation. The conventional methods are biased toward the long, strong fibers in cotton, whereas the high speed instruments use less accurate, indirect methods to measure bundle mass and produce a force measurement that is confounded by differences in fiber crimp. When we compared single instrument testing (Pressley and Stelometer) with the HVI technology for evaluation of fiber properties is faster and coast less per measurement. The disadvantage of HVI for genetic modification for fiber properties may be reduced accuracy and ability to separate small differences. The HVI instrument had a highly significant effect on all studied fiber properties i.e. the micronaire reading , maturity index , fiber length , uniformity index , fiber strength , short fiber index, reflectance degree and yellowness degree .The highest mean value were (3.18), (85%) , (35.7mm), (86.4 %) , (47.6g/tex) , (5.7 %) , (76.0) and (9.4),respectively. of the maturity index, while the CCS instrument possessed the lowest mean of these traits. HVI measurements were calibrated across instruments using USDA cotton calibration standards making it possible to compare results from different instruments over a long period of time. In addition, cotton testing laboratories use cottons of known values throughout the day to check for a possible drift in measurements over time.