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The natural fibers- and synthetic fibers-reinforced polymer hybrid composites have the advantages of low economical costs, good mechanical properties, low hygroscopicity and environmental sustainability. In this work, the flax fibers (F), basalt fibers (B) and polypropylene long fibers (PP) were used to prepare the wrapped yarns with hybridizing on yarn level. The polypropylene was a thermoplastic synthetic resin with excellent properties and low melting point. The wrapped yarns and PP yarns were further manufactured on the unidirectional fabrics by three weaving methods, which were laminated and hot pressed to prepare the hybrid composites. The effects of weaving methods, PP content and basalt fibers content in wrapped yarns on the mechanical properties of composites were investigated. It was found that the two PP yarns in the core of the hybrid-wrapped yarns helped the composites to attain good mechanical properties. As compared to 3F2PP composites, the tensile strength and flexural strength of 1F2B2PP hybrid composites were increased to 213.2% and 32.4%, respectively. As the basalt fiber content increased, the damage degree of the F/B composites reduced and the composites showed good impact energy absorption. The impact damage modes of the all F/B composites were mainly circular pit and band-shaped failure. Furthermore, the multi-scale finite element models of the hybrid composites were established to predict and simulate the mechanical properties. [ABSTRACT FROM AUTHOR]

Fiber‐reinforced polymers (FRP) feature high strength‐to‐weight ratio amongst the emerging class of natural composites. This paper presents the impact of the glass fiber on the tensile strength of the flax epoxy laminate. The mechanical behavior and damping characteristics of flax fiber reinforced polymer (FFRP) and the hybrid flax‐glass fiber reinforced polymer (HFRP) are experimentally investigated. Both the flax and hybrid FRPs are made using vacuum infusion process. The specimens without and with holes of 4, 5, and 6 mm in diameter are subjected to tensile test using acoustic emission monitoring and free vibration test. In the former testing, HFRP resulted in higher peak frequencies and cumulative counts. Also, the natural frequency and damping factor of HFRP vary proportionately with the hole size, as identified in the latter tests. Different damage mechanisms during the tensile test revealed that the presence of glass fibers in HFRP increased resistance for certain damage mechanisms. Highlights: Adding glass fiber to flax fiber reinforced polymer (FFRP) creates a hybrid FRP (HFRP) with increased resistance to damage and improved damping characteristics.HFRP exhibits a distinction in failure mechanisms compared to FFRP.The study utilizes acoustic emission (AE) to identify various damage mechanisms in the material, providing a more detailed information.The addition of glass fibers in HFRP leads to a more pronounced increase in damping factors. [ABSTRACT FROM AUTHOR]

Purpose: This study examines how different stacking sequences of bamboo and flax fibers, treated with 5% aqueous sodium hydroxide (NaOH) and filled with 6wt% titanium oxide (TiO2), affect the physical, mechanical and dry sliding wear resistance properties of a hybrid composite. Design/methodology/approach: Composites with different fiber stacking arrangements were developed and tested per American Society for Testing and Materials (ASTM) standards to evaluate physical, mechanical and wear resistance properties, focusing on the impact of flax fiber mats at intermediate and outer layers. Findings: The hybrid composite significantly outperformed composites reinforced solely with bamboo fibers, showing a 65.95% increase in tensile strength, a 53.29% boost in flexural strength and a 91.01% improvement in impact strength. The configuration with multiple layers of flax fiber mat at intermediate and outer levels also demonstrated superior wear resistance. Originality/value: This study highlights the critical role of stacking order in optimizing the mechanical properties and wear resistance of hybrid composites. The findings provide valuable insights for the design and application of advanced composite materials, particularly in industries requiring high performance and durability. [ABSTRACT FROM AUTHOR]

Highlights The effect of the asymmetric distribution of woven flax fiber on the interlaminar fracture toughness of carbon fiber‐reinforced polymer (CFRP) is investigated experimentally via a double cantilever beam test, and the results are backed by analytical and numerical analysis. Four hybrid configurations are fabricated with different stacking sequences of (CFRP) and flax fiber‐reinforced polymer (FFRP) plies. The results of hybrid specimens are compared with those of all CFRP and all FFRP specimens. The hybrid composite with one carbon/flax fiber layer at the interface requires the highest critical energy release rate, GC, to initiate cracks. A resin layer on top of the flax plies and a carbon fiber imprint in that layer are observed, thus signifying an increase in GC for the hybrid composites with dissimilar interface layers. Varying the number of carbon/flax fiber layers at the interface adversely affects GC. Mode II contribution to the GC was verified analytically for asymmetric hybrid configurations. The agreement between experimental, numerical, and analytical results is excellent. The hybridization of flax with carbon enhances the fracture toughness of CFRP while providing an opportunity to achieve lightweight, high‐performance, and eco‐friendly structures. Flax fiber is used to increase the fracture toughness (GC) of CFRP Asymmetric carbon/flax fiber hybrid composites are designed for this purpose One interface carbon/flax hybrid exhibits a 70% increase in GC Blocking the plies together results in reduced GC and mode‐II fracture as well Numerical and analytical analysis agrees well with experimental results [ABSTRACT FROM AUTHOR]

This study examines the mechanical properties, specifically strength and stiffness, of technical hemp and flax fibers grown in Romania. Tensile testing was employed to determine stress–strain curves and the Young's modulus and to assess the failure strength of both fiber types. Although samples of various lengths were tested, no significant length-dependent variations were observed. However, a strong dependence on fiber diameter was noted, with the smallest diameters approaching the documented strength of elementary fibers. Due to the considerable variability in the experimental results pertaining to the characteristics of the reinforced fibers, a statistical analysis using a two-parameter Weibull distribution was employed. The analysis revealed three distinct stress–strain curve profiles, i.e., linear, bi-linear, and tri-linear patterns, with the average ultimate stress ranging from 412 to 566 MPa for hemp and 502 to 598 MPa for flax. [ABSTRACT FROM AUTHOR]

Highlights This study aimed to evaluate the effect of incorporating Mahua oil cake microcellulose (MOCM) on the mechanical and sound absorption properties of flax fiber‐reinforced polymer composites fabricated using the compression molding technique. X‐ray diffraction (XRD) analysis revealed that MOCM had a crystallite size (Cs) of 6.71 nm and a crystallinity index (CI) of 63.25%, indicating its potential for mechanical reinforcement. Thermogravimetric analysis (TGA) demonstrated that MOCM exhibits thermal stability up to 355.44°C, which is suitable for high‐temperature applications. Mechanical testing revealed that the incorporating 7.5 wt.% MOCM into flax fiber composites achieved optimal results, with the tensile strength reaching 70.23 MPa, flexural strength peaking at 113.23 MPa, and impact strength at 33.4 kJ/m2. Scanning electron microscopy (SEM) analysis confirmed the improved interfacial bonding between the fibers and matrix, contributing to enhanced mechanical performance. The noise reduction coefficient (NRC) and sound absorption coefficient (SAC) also improved with increasing MOCM content, with the highest SAC (0.328) and NRC (0.312) values observed at 10 wt.% MOCM. These findings suggest that MOCM enhances both the mechanical and acoustic properties of flax fiber composites, making it a promising material for applications in the automotive, aerospace, and construction industries, where both structural integrity and sound absorption are critical. Novel use of MOCM as sustainable cellulose for polymer composites Synergy of MOCM and flax fibers enhances mechanical and acoustic properties 7.5% MOCM compositions optimally improves strength and sound absorption MOCM: eco‐friendly alternative to synthetic fillers in polymers Comprehensive MOCM characterization for future biomaterial applications [ABSTRACT FROM AUTHOR]

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In this study, glass fiber and flax fiber reinforced with epoxy and ZnO nanofiller were used to create composites utilizing the hand layup method. The purpose of this study is to develop a novel hybrid polymer‐matrix composite that can be employed in various application areas such as aerospace, sports, medical equipment, railways, etc. The fabricated composite was made with epoxy as a matrix material reinforced with nano‐ZnO, glass fiber, and flax fiber. Six fiber layers with varying fiber orientations were inserted into the matrix in a specific stacking order. The results show the maximum tensile, flexural, impact, and ILSS as the values of 264.74 MPa, 492.12 MPa, 595.72 J/m, and 50.05, respectively. Along with the mechanical properties, Physical characterization such as density, void content, thickness swelling, moisture content, and water absorption tests were conducted. FE‐SEM test was conducted to check the uniformity of nanoparticles in the matrix material and the breakdown of fibers. [ABSTRACT FROM AUTHOR]

Flax fibers contain naturally colored substances, which need to be removed by bleaching to produce excellent flax-based textiles in the subsequent process. However, the traditional bleaching process has the disadvantages of high temperature, large water consumption and high chemical oxygen demand (COD) value. Therefore, an appealing alternative to make flax fiber more sustainable is to design an environmentally friendly bleaching process, which has the advantages of low water usage, easy operation at ambient temperature and without addition of chemicals. In this paper, the influence of ozone bleaching on the optical property of flax fibers at different parameter conditions (reaction phase, ozone concentration, bleaching time, water pickup value, initial pH value) was investigated. The physicochemical properties of fiber samples after ozone bleaching were analyzed and compared with those of traditional bleached fibers. Results showed that the lightness and whiteness index of SFT-O3-Gas-70% increased to 80.85 and 53.33, yellowness index decreased to 10.14 (ozone concentration 20%, 20 min, WPV 70%, pH 2.0), which was comparable with the SFT-TMB (80.75, 51.87 and 11.33). SEM analysis showed that the non-cellulosic components (hemicelluloses and lignin) on the fiber surface were removed after bleaching treatment. The crystallinity and thermal stability of samples after bleaching treatment increased due to the removal of non-cellulosic components. Compared with the SFT-TMB (16.07 cN/tex and 1166), the tenacity and degree of polymerization (DP) of SFT-O3-Gas-70% decreased to 11.40 cN/tex and 779, respectively. The whole ozone bleaching process is under gas phase, normal temperature and pressure conditions, which greatly reduces water consumption and COD values of bleach wastewater. This study provides some guidance on the use of ozone for bleaching lignocellulosic fibers and the selection of cellulose protectants. [ABSTRACT FROM AUTHOR]

This study enhances the compressive performance of polylactic acid (PLA) bio-based materials by adding flax fibers, and explores the effects of silane coupling agent concentration and flax fiber mass fraction on the compressive mechanical properties of PLA/Flax composite materials. Firstly, scanning electron microscopy (SEM) was used to analyze the microstructure of flax fibers treated with silane coupling agents. PLA/Flax composite material samples with different ratios were prepared using melt blending and injection molding methods. The elastic modulus and yield strength of each sample were measured using a 100 kN universal testing machine. Finally, the microstructure of the cross-section of the composite material was analyzed using SEM, revealing the fiber distribution and interface characteristics inside the material. It was found that, when the flax fiber content is 5.25% and treated with a 2% silane coupling agent, the elastic modulus of the composite material reaches a maximum value of 0.63 GPa, which is 24.2% higher than that of pure PLA material. And the yield strength increased to 124.7 MPa, with an increase of 15.6%. At the same time, the flax fiber treated with a 2% silane coupling agent had a tighter interface compatibility with polylactic acid. [ABSTRACT FROM AUTHOR]

Highlights This study evaluates the sliding wear behavior of hybrid composites made of epoxy reinforced with alternating layers of flax fiber mats and steel wire mesh. The aim is to enhance the wear resistance of flax fiber‐epoxy composites by incorporating steel wire mesh. Specifically, three composite types are produced by varying their stacking sequences using the simple hand layup technique. Dry sliding wear tests are performed on a pin‐on‐disc test rig under different conditions according to ASTM G99 standard. Taguchi analysis is performed using an L25 orthogonal array and it reveals that sliding velocity is the most critical factor, followed by normal load, in affecting the wear rate of the steel‐flax‐epoxy hybrid composite. Subsequently, a steady‐state wear analysis shows that sliding velocity and normal load increase the specific wear rate (SWR), while steel reinforcement decreases it. ANOVA results indicate that sliding velocity significantly impacts wear rates to the extent of 69.47% for flax‐epoxy composite and more than 70% for flax‐steel‐epoxy composites. Additionally, electron microscopy is used to study the worn surfaces of the composites to determine the wear mechanisms. Successful fabrication of flax‐steel wire mesh reinforced hybrid composites. Wear behavior of multi‐layer composites with different stacking sequence. Use of statistical technique for the prediction of wear rate. Wear mechanisms are identified using electron microscopy. [ABSTRACT FROM AUTHOR]

The availability of a sustainable technique for degumming lignocellulose fibers is a challenge for the fiber processing industry. Removal of non-cellulosic content from lignocellulose fibers is essential for improving their mechanical and chemical properties, which makes the fibers more suitable for various applications. Herein, a catalytic Fenton-based oxidation process was employed to isolate microcellulose fibers from raw flax fibers. Various complementary methods such as FT-IR/NMR spectroscopy and TGA were used to obtain insight into the thermal behavior of the treated fibers. The morphology of the fibers was studied using Scanning Electron Microscopy (SEM), whereas the surface chemical properties of the fibers was evaluated by a dye-based adsorption method, along with a potentiometric point-of-zero-charge method. To obtain fibers with suitable properties, such as uniform fiber diameter, several Fenton reaction parameters were optimized: pH (7), reaction time (15 h), iron sulfate (2 wt.%), and hydrogen peroxide (10 wt.%). The results indicate that, under the specified conditions, the average diameter of the raw fibers (12.3 ± 0.5 µm) was reduced by 58%, resulting in an average diameter of 5.2 ± 0.3 µm for the treated fibers. We demonstrate that the treated fibers had a lower dye adsorption capacity for methylene blue, consistent with the smoother surface features of the treated fibers over the raw flax fibers. Overall, this study contributes to utilization of the Fenton reaction an efficient oxidation technique for the production of lignocellulose fibers with improved physicochemical properties, such as reduced fiber diameter distribution, in contrast with traditional alkali-based chemical treatment. [ABSTRACT FROM AUTHOR]

This research examined the response of flax-fiber-reinforced composites (FFRCs) to simulated outdoor conditions involving repeated exposure to salt fog and drying. The study investigated the effect of cycles on the toughness of the FFRCs. To achieve this, the composites were exposed to humidity (salt fog) for 10 days, followed by 18 days of drying in cycles. A total of up to 3 cycles, each lasting 4 weeks, were conducted over a 12-week period. Throughout this process, changes in the material's weight, water absorption, and mechanical properties were monitored by water uptake and three-point bending tests. The findings revealed the significant impact of these humid–dry cycles on the mechanical response of the FFRCs. When exposed to humid environments without drying, the composite's toughness increased significantly, due to a weakening effect more pronounced for stiffness, with strength reductions of about 20%. However, subsequent drying partially restored the material's performance. After 18 days of drying, the composite regained most of its initial performance. [ABSTRACT FROM AUTHOR]

There is a growing demand for high-quality natural fibers, including flax fibers, which possess bioactive compounds with antioxidant, antibacterial, and anti-inflammatory properties. Traditional methods like dew retting are commonly used for flax fiber production, but alternative approaches are sought for enhanced fiber quality. This study presents a novel method involving cottonization to improve the quality of flax fibers obtained from low-quality decorticated fibers. The research evaluates the quality enhancement through various stages of the new method, comparing it with dew retting. Studies conducted on both transgenic (B14) and non-transgenic flax fibers revealed a decrease in fiber polymers and bioactive compounds after cottonization compared to dew retting. However, despite this reduction, the antioxidant potential of cottonized fibers increased significantly. Moreover, cottonized flax fibers exhibited high antimicrobial activity, particularly against Pseudomonas aeruginosa. Furthermore, extracts from both transgenic and non-transgenic cottonized flax fibers showed cytotoxic effects on hamster lung fibroblast cells, indicating potential future applications in cancer research. These findings highlight the potential of cottonization in enhancing the quality and bioactivity of flax fibers, paving the way for further exploration in various applications, including medical and textile industries.

The modification method of grafting multi-walled carbon nanotubes (MWCNT, abbreviated as CNT in this paper) on the surface of flax fibers was investigated, i.e. CNT were grafted onto the surface of flax fibers by silane coupling agent under the action of ultrasonic waves to form covalent bonding. The tensile strength of CNT grafted flax fiber is 22% higher than that of untreated flax fiber monofilament. The tensile strength of FFRP composites after CNT grafting treatment increased by 14.2%; however, the tensile modulus of single fiber and composites did not show a significant increase, the interfacial shear strength of the fiber-resin is 38.3% higher than that of untreated filament. The improvement of the contact angle after grafting was investigated by observing the surface morphology, and the surface of flax filament was characterized by scanning electron microscopy and atomic force microscopy. Also the elemental changes of the flax single fiber surface before and after the treatment were analyzed using X-ray photoelectron spectroscopy. The results showed that the tensile strength of flax single fibers, its composites, and interfacial shear strength of fiber-matrix was improved after CNT grafting treatment but the increase of modulus was not obvious.

The work deals characteristics of new flax Hera variety in terms of fiber quality with regard to agronomic assessment and seeds quality. The results of the analyzes were related to the reference varieties Nike, Sara and Modran grown in Poland in 2022 season. The study included evaluation of agrotechnical experiment, flax straw and fiber evaluation taking into account the morphology and surface as well cross section of flax fiber. Moreover, seeds quality assessment were conducted. Hera variety was characterized by the highest total (6.27 t/ha, 0.627 kg/m2) and straw yield (5.16 t/ha, 0.516 kg/m2). Straw of Hera variety was characterized by the best average total (78.5 cm) as well as average technical (66.5 cm) length and average diameter (1.43 mm). In addition, it has fiber to raw straw content (16.42%) at a level comparable to the reference varieties. The metrological analysis of the fiber showed that the Hera variety fiber can be a good raw material for production of yarns.

This study investigates the chemical modification of short flax fiber and the resulting sorption properties concerning Cu(II) and Cd(II) ions. A two-stage chemical modification process involving the oxidation of flax fiber with sodium metaperiodate followed by treatment with polyethylenepolyamine produced a new sorbent for water purification from heavy metal ions. Kinetic experiments determined the time to reach sorption equilibrium in the heterophase system "aqueous solution of copper/cadmium sulfates–sorbent" and found that the degree of metal ion extraction by the modified sorbent increased by about 20% compared to the initial fiber. The experimental sorption isotherms were analyzed using the Langmuir model, which was found applicable to describe the sorption process of heavy metal ions by cellulose-based sorbents. The maximum sorption capacities (А∞) of native and modified flax fibers with respect to heavy metal ions were determined, revealing that Cu(II) ions are more efficiently extracted by the developed sorbent compared to Cd(II) ions. Scanning electron microscopy of the original and modified flax fibers indicated changes in the surface microrelief due to modification. Elemental analysis reflected changes in the composition of the modified sorbent compared to native flax fiber. The improvement in the equilibrium-kinetic characteristics of short flax fiber resulting from its modification with polyethylenepolyamine is attributed to the presence of new sorption-active groups, as confirmed by IR spectroscopy and elemental analysis. [ABSTRACT FROM AUTHOR]

The main motivation for this research was to improve the properties of geopolymers by reinforcement using synthetic and natural fibers, and to gain new knowledge regarding how the nature and/or the quantity of reinforcement fibers influences the properties of the final geopolymers. The main objective was to investigate the effects of different types of reinforcement fibers on the properties of the geopolymers. These reinforcement fibers were mainly environmentally friendly materials that can be used as alternatives to ordinary Portland cement. The authors used fly ash and river sand as the raw materials for the matrix, and added carbon fibers (CF), flax fibers (FF), or a hybrid of both (CFM) as reinforcements. The samples were prepared by mixing, casting, and curing, and then subjected to various tests. The main research methods used were compressive strength (CS), flexural strength (FS), water absorption (WA), abrasion resistance (Böhme's disk method), microstructure analysis (SEM), chemical composition (XRF), and crystal structure analysis (XRD). The results showed that the addition of fibers partially improved the mechanical properties of the geopolymers, as well as reducing microcracks. The CF-reinforced geopolymers exhibited the highest compressive strength, while the FF-reinforced geopolymers showed the lowest water absorption. The authors, based on previous research, also discussed the factors that influence fiber-matrix adhesion, and the optimal fiber content for geopolymers. [ABSTRACT FROM AUTHOR]

In order to achieve efficient extraction of flax fiber, supercritical CO2 technology and biological enzyme impregnation technology were combined to degum the waste flax straw. The extraction process of supercritical CO2 treatment thme, treatment temperature and treatment pressure was optimized by response surface design. The relationship between supercritical CO2 assisted enzymatic degumming process parameters and degumming effect was studied by orthogonal test with fiber residual gum rate, mass loss rate, breaking strength, diameter and fineness as detection indexes, and compared with traditional chemical degumming, compound enzyme degumming and simple supercritical CO2 degumming process. The results show that the optimum process of supercritical CO2-assisted enzymatic degumming was as follows; the treatment pressure was 18 MPa, the treatment temperature was 64 °C, the CO2 flow rate was 20 g/min, and the amount of composite enzyme was 8% (xylanase; β-mannanase; pectinase mass ratio was 4.4:2.3:1.3). The flax fiber was degummed for 40 min. Compared with other processes, it was found that the residual gum rate of flax fiber treated by supercritical CO2 system was small (14.45 %), the damage to cellulose was small, and the fiber strength (47.56 cN) was retained to a large extent, which basically met the spinning requirements. [ABSTRACT FROM AUTHOR]

The composite industry urgently needs to develop effective and efficient surface treatment techniques for high-strength plant fibers. A newly designed hybrid approach which combines surface treatment techniques of three categories is studied in this research, in which sodium bicarbonate treatment is conducted to 'gently' clean the flax fiber, silane treatment served to add functional group and silane-grafted cellulose nanocrystals (CNCs) are applied to fiber surface to promote fiber-matrix interaction. Three processes are designed in order to combine silane treatment and CNC treatment. In the first process, CNCs were directly deposited on flax fabric after which flax fabric with CNCs was subjected to silane treatment. In the second process, flax fabric was simultaneously subjected to CNC deposition and silane treatment. In the third process, CNCs were separately subjected to silane treatment and later collected using a centrifuge. Later, silane-grafted CNCs were deposited flax fabric. The combined NaHCO3-silane treatment improved the tensile strength of flax/polypropylene composites by 26.6%. It was also confirmed that CNCs could enhance fiber/matrix interface via mechanical interlocking. As the concentration of CNC suspension increased, density of CNCs on fiber surface increased. When the concentration is 5 g/L, optimum performance of flax/polypropylene composites is observed. In terms of moisture absorption, it was found that NaHCO3-silane treatment could reduce moisture absorption (by 49.8%) while CNCs induce higher moisture content (by 31.1% when CNC concentration was 10.0 g/L). More importantly, the results of this study indicated that the moisture absorption and mechanical properties of composites could be largely affected by the nature of the interface. Proper fiber/matrix interface engineering can reduce moisture absorption and enhance mechanical properties. [ABSTRACT FROM AUTHOR]

Purpose: This study explores how titanium oxide (TiO2) filler influences the specific wear rate (SWR) in flax fiber-reinforced epoxy composites (FFRCs) through a Taguchi approach. It aims to boost abrasive wear resistance by incorporating TiO2 filler, promoting sustainable and eco-friendly materials. Design/methodology/approach: This study fabricates epoxy/flax composites with TiO2 particles (0–8 wt%) using hand layup. Composites were tested for wear following American Society for Testing and Materials (ASTM) G99-05. Statistical analysis used Taguchi design of experiments (DOE), with ANOVA identifying key factors affecting SWR in abrasive sliding conditions. Findings: The study illuminates how integrating TiO2 filler particles into epoxy/flax composites enhances abrasive wear properties. Statistical analysis of SWR highlights abrasive grit size (grit) as the most influential factor, followed by normal load, wt% of TiO2 and sliding distance. Grit size has the highest effect at 43.78%, and wt% TiO2 filler contributes 15.61% to SWR according to ANOVA. Notably, the Taguchi predictive model closely aligns with experimental results, validating its reliability. Originality/value: This paper integrates TiO2 filler and flax fibers to form a novel hybrid composite with enhanced tribological properties in epoxy composites. The use of Taguchi DOE and ANOVA offers valuable insights for optimizing control variables, particularly in natural fiber-reinforced composites (NFRCs). [ABSTRACT FROM AUTHOR]

Due to the loose structure and low cohesion of natural sand, many improved techniques have been tried to overcome this deficiency. When fiber reinforcement technology is applied to reinforce sand, there are deficiencies such as low cohesion and limited strength improvement effect. This paper studies the effect of xanthan gum (XG) for the improved fiber reinforcement technique. Biopolymers are popular in soil improvement as an environmentally friendly alternative. Unconfined compressive strength (UCS) tests, direct shear tests, and Brazilian splitting tests were performed to investigate the effect of different XG content and drying times on the mechanical properties of fiber-reinforced sandy soils treated with XG. The scanning electron microscope (SEM) was used to investigate the microstructure of the materials. The test results show that the extension of drying time and the increase of XG content have a positive effect on strength and the optimal content of XG is 4% for UCS and 3% for tensile strength and shear strength. The maximum UCS and elastic modulus are 4829 kPa and 171.65 MPa, respectively, the maximum shear strength, cohesion, and tensile strength can be increased to 938.9 kPa, 620 kPa, and 807 kPa, respectively, and the optimal drying time is 14 days. SEM analysis showed that the XG enhanced the strength by filling the pores between the particles, adhering to the surface of the soil particles and the fiber mesh, increasing the roughness and interlocking force of fibers. The conclusion shows that XG, as an environmentally friendly improvement material, has a great effect on improving the strength of soil and can provide a solution to solve the deficiency of fiber reinforcement technology and improve its application in sandy soil. [ABSTRACT FROM AUTHOR]

High specific impact strength and stiffness are demanded in various applications, leading to the widespread utilization of fiber‐reinforced polymers. Synthetic fiber‐reinforced polymers have been used to meet these engineering requirements. However, the current popularity of biocomposites arises from their environmental friendliness, ease of availability, and affordability, making them a favored alternative to synthetic‐based fiber‐reinforced polymers. An assessment must be conducted to determine whether biocomposites can replace their synthetic fiber counterparts, necessitating a thorough investigation into their impact behavior. This study aims to unveil the impact performance of hybrid biocomposites made from unidirectional prepregs comprising flax/polypropylene fibers and nonwoven mats composed of hemp/polypropylene fibers. The impact performance of hybrid biocomposites has also been studied concerning the number of layers and stacking sequence. Eight different designs of biocomposite plates are manufactured through compression molding and subsequently subjected to high‐velocity impact tests. Additionally, numerical simulation using the FEM is utilized to model and analyze the impact behavior of one specimen. The test results indicate that each design possesses unique characteristics and impact behaviors differ. Highlights: Adding prepreg significantly improved mechanical performance in the biocomposites.Performance enhancement varies depending on the stacking sequence.Adding multiple layers of UD prepregs enhances mat impact performance.Numerical simulations validate the Tsai‐Wu criterion for impact testing. [ABSTRACT FROM AUTHOR]

This study aims to enhance value addition to agricultural byproducts to produce composites by the solution casting technique. It is well known that PLA is moisture-sensitive and deforms at high temperatures, which limits its use in some applications. When blending with plant-based fibers, the weak point is the poor filler–matrix interface. For this reason, surface modification was carried out on hemp and flax fibers via acetylation and alkaline treatments. The fibers were milled to obtain two particle sizes of <75 μm and 149–210 μm and were blended with poly (lactic) acid at different loadings (0, 2.5%, 5%, 10%, 20%, and 30%) to form a composite film The films were characterized for their spectroscopy, physical, and mechanical properties. All the film specimens showed C–O/O–H groups and the π–π interaction in untreated flax fillers showed lignin phenolic rings in the films. It was noticed that the maximum degradation temperature occurred at 362.5 °C. The highest WVPs for untreated, alkali-treated, and acetylation-treated composites were 20 × 10−7 g·m/m2 Pa·s (PLA/hemp30), 7.0 × 10−7 g·m/m2 Pa·s (PLA/hemp30), and 22 × 10−7 g·m/m2 Pa·s (PLA/hemp30), respectively. Increasing the filler content caused an increase in the color difference of the composite film compared with that of the neat PLA. Alkali-treated PLA/flax composites showed significant improvement in their tensile strength, elongation at break, and Young's modulus at a 2.5 or 5% filler loading. An increase in the filler loadings caused a significant increase in the moisture absorbed, whereas the water contact angle decreased with an increasing filler concentration. Flax- and hemp-induced PLA-based composite films with 5 wt.% loadings showed a more stable compromise in all the examined properties and are expected to provide unique industrial applications with satisfactory performance. [ABSTRACT FROM AUTHOR]

Flax fiber cloth and polylactic acid (PLA) were melted and blended to produce PLA/flax non-woven fabric composites through injection molding. The effects of flax fiber addition on the mechanical properties, thermal properties, and degradation performance of composites were explored. The results show that the addition of flax fiber improves the mechanical properties, thermal properties, and energy storage modulus of PLA/flax nonwoven fabric degradable composites, enhances the crystallinity of the composites, and enhances the degradation performance of the composites. When the flax fiber content is 20%, the tensile strength, impact strength, and bending modulus of the composites are 66.0 MPa, 5.52 kJ/m², and 4.0 GPa, respectively. The crystallinity of the composites reaches 13.89%, and the Vicat softening temperature is 141.32 °C. At the 40 d of degradation, the weight loss rate of the composite with the addition of 20% flax fiber reaches the highest, which is 12.03%. The research results provide data support for the application of PLA/ flax fiber composites. [ABSTRACT FROM AUTHOR]

Linum usitatissimum commonly known as flax fibers, emerges as a promising reinforcement phase for artificial polymer resins, boasting ecological benefits, low density, and easy accessibility. However, the mechanical behavior of such composites hinges crucially on factors such as fiber mat thickness, nanoTiO2 filler content, and the application of cryogenic treatment. Addressing this complex interplay, this study employs a hand lay-up technique for composite construction, subjecting nanocomposite plates to the challenging liquid nitrogen conditions at 77 K post-manufacture. Recognizing the need for an optimized approach, Response Surface Methodology (RSM) based on Box-Benhken designs is employed to enhance the mixing features of linum usitatissimum polymer composites. The study calculates anticipated mechanical strength values through rigorous ANOVA inferential analysis, uncovering the pivotal roles played by fiber mat thickness, nanofiller content, and cryogenic treatment in the two feature interactions (2FI) model components. The methodology proves robust with high R2 values (0.9670 for tensile, 0.9845 for flexural, and 0.9670 for interlaminar shear strength) consistently aligning with experimental findings. The study culminates in identifying optimized parameters for maximal mechanical properties--300 gsm flax fiber thickness, 5 wt.% nano TiO2 concentration, and a 15-min cryogenic treatment--a result that advances our understanding of fundamental factors influencing composite performance and provides practical guidelines for applications in fields requiring superior mechanical strength in challenging environments. [ABSTRACT FROM AUTHOR]

In comparison to the traditional fibers, flax fiber has many features, i.e. high fracture strength, small tensile deformation, better bending and large torsion stiffness. Flax fiber cement-based materials are the civil engineer materials with the broad application prospects. The research statuses and the existing problems of cementbased materials with flax fiber were discussed from 3 aspects, i.e. the physical and chemical properties of flax fiber, the role of flax fiber on the behaviors of cement-based materials, the properties improvement of cement-based materials with flax fiber. Based on above investigation results, the following research directions were drawn: enhance the using of flax fiber to replace polypropylene fiber on cement-based materials; revel the long-term properties of cement-based materials with flax fiber at the wet conditions; build the damage model of flax fiber cement-based composite materials under the combined actions of three-axis stress and wet conditions; improve the application performance of cement-based composite materials with flax fiber through increasing itself strength of flax fiber and improving the interfacial adhesion between flax fiber and cement-based materials. [ABSTRACT FROM AUTHOR]

Flax fibers have been shown to have comparable mechanical properties to some conventional synthetic fibers. Flax fabrics with different textile structures show differences in resistance against mechanical loads mainly rooted in fabric orientation and the resultant resin impregnation. Thus, in this study, flax fabrics with three different textile structures, fine twill weave, coarse twill weave and unidirectional, were used as reinforcements in an epoxy matrix. The surfaces of the fabrics were chemically treated using an alkaline treatment, and the alterations in fabric crystallinity index (CrI) were determined using X-ray diffraction (XRD). Experimental results confirmed that textile structures and CrI had significant effects on the mechanical properties of composites. Although an increment in CrI, resulting from chemical treatment, always enhanced tensile and flexural properties, it adversely affected damage development once composites were exposed to impact load. In terms of textile structures, unidirectional fabric outperformed woven fabrics in tensile and flexural properties while in impact properties, the latter had a better performance inducing less damage development. Finally, the mechanism of damage development in different composites was discussed in detail using Scanning Electron Microscopy (SEM) images. It is envisaged that the results of this study will provide an insight that will lead to the proper choice of the optimal kind of flax fabric for different applications. [ABSTRACT FROM AUTHOR]

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Weather has significant impact on plant growth and development. It is important to analyze the influence of changing climate conditions on the expression of plant agronomic characters. Two flax varieties were grown from 1987 to 2018 in the Northwest of Russia. Weather conditions and their influence on flax agronomic characters were analyzed using the variance and correlations analyses. Significant influence of conditions of a particular year on the manifestation of all evaluated characters was revealed. Starting from June, high temperatures accelerate plant development at all stages. Prolongation of the germination-flowering period is most important for improving fiber productivity, while fast ripening in hot weather after flowering is preferable for the formation of high-quality fiber. Such data give a possibility to predict the yield amount and quality. The use of weather conditions data also makes possible a comparison of the results obtained in different years. The suggested method of classifying meteorological conditions of a year can be used in other genebanks for systematizing and analyzing the results of crop evaluation in the field. The correlation analysis revealed 3 correlated pleiades, namely (1) of productivity, (2) of fiber quality and yield, and (3) of the growing season phase durations, the sums of active temperatures and precipitation during each period. The great influence of growing conditions on the economically valuable traits indicates the necessity of searching for genotypes with stable character manifestations for breeding new varieties with stable yields and good fiber quality. [ABSTRACT FROM AUTHOR]

Due to the high cost of transportation and the lack of established, affordable recycling routes, the rate of recycling of previously used polystyrene foam is extremely low. In this study, a novel treatment technique will be used to examine the feasibility of using waste polystyrene foam as a raw material to produce wood plastic composite (WPC). Where, the recycled polystyrene (rPS) foam waste was first dissolved in methylene chloride and compounded directly with flax fiber (FF) and additives forming a composite paste. The composite paste was then passes through vacuum distillation process for drying the composite paste and also for solvent recovery to reuse it in a further process. The dried composite was processed through thermal mixer extruding and compression molding processes to form the final WPC. The study discovered that WPC with 60 parts per hundred parts of resins (phr) of FF and 2 phr of dioctylphthalate (DOP) may be used to create rPS/FF composite with a proper tensile strength of 19.3 MPa, flexural strength of 78 MPa and compressive strength of 173 MPa compared to another WPS,s based on PVC, HDPE and PP. In addition of that the resulted composite possesses a great potential in manufacturing WPC with environmental and economical demanding application as wooden furniture and as a wooden panels for cladding the exterior building faces. [ABSTRACT FROM AUTHOR]

In the present research endeavor, the waste shells of pistachio and walnut have been used in the form of fillers to develop hybrid flax epoxy composites. The effect of hybridization on the developed composites was studied in terms of thermal, mechanical, and morphological properties. The properties like tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength, and shore hardness were evaluated to ascertain the mechanical behavior. The thermogravimetric analysis of the composites was also performed in order to determine the thermal stability of the developed composites. The results revealed that pistachio shell filler-based flax/epoxy composites showed improved tensile strength and tensile modulus by over 73.26% and 42.53% in comparison to the control specimen. The walnut shell filler-based flax/epoxy composites also exhibited improved tensile strength and tensile modulus by 66.41% and 17.1% compared to the control specimen. Whereas, the hybrid filler-based flax/epoxy composites were found to be thermally more stable. The fractography of the developed composites was also studied using scanning electron microscope which revealed good filler distribution in the epoxy matrix. [ABSTRACT FROM AUTHOR]

Significant progress has been made in recent years in the use of atmospheric pressure plasma techniques for surface modification. This research focused on the beneficial effects of these processes on natural by-products, specifically those involving natural fiber-based materials. The study explored the deposition of hydrophobic organosilicon-like thin films onto flax fibres through plasma-enhanced chemical vapour deposition (PECVD), using tetramethylcyclotetrasiloxane (TMCTS) as the precursor. After the successful deposition of hydrophobic organosilicon-like thin films onto the flax fibres, polylactic acid (PLA) composite materials were fabricated. This fabrication process sets the stage for an in-depth analysis of the modified materials. Subsequently, these flax fabrics were subjected to meticulous characterization through scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. The results demonstrated successful TMCTS deposition on the surface which led to a complete hydrophobization of the flax fibers. Mechanical tests of the PLA/flax fibre composites revealed a significant improvement in load transfer and interfacial compatibility following the surface modification of the flax fibres. This improvement was attributed to the enhanced adhesion between the modified fibres and the PLA matrix. The findings highlight the potential of TMCTS-based PECVD as a practical surface modification technique, effectively enhancing the mechanical properties of PLA/flax fibre composites. These developments open exciting possibilities for sustainable and high-performance composite materials in various industries. [ABSTRACT FROM AUTHOR]

Based on the morphology structure and chemical composition of flax fiber, the factors affecting antibacterial property of flax fiber were analyzed. The effects of degumming, kinds of dyes and dye auxiliaries on the antibacterial property of flax fiber were summarized. The physical and chemical antibacterial finishing methods were summarized. It is considered that on the basis of antibacterial property of flax fiber, adding natural antibacterial agents, physical antibacterial finishing and plant dye dyeing can effectively reduce the loss of antibacterial components in the process of production and processing of flax fiber, and antibacterial property of flax fabric can be further improved. [ABSTRACT FROM AUTHOR]

The availability of a sustainable technique for degumming lignocellulose fibers is a challenge for the fiber processing industry. Removal of non-cellulosic content from lignocellulose fibers is essential for improving their mechanical and chemical properties, which makes the fibers more suitable for various applications. Herein, a catalytic Fenton-based oxidation process was employed to isolate microcellulose fibers from raw flax fibers. Various complementary methods such as FT-IR/NMR spectroscopy and TGA were used to obtain insight into the thermal behavior of the treated fibers. The morphology of the fibers was studied using Scanning Electron Microscopy (SEM), whereas the surface chemical properties of the fibers was evaluated by a dye-based adsorption method, along with a potentiometric point-of-zero-charge method. To obtain fibers with suitable properties, such as uniform fiber diameter, several Fenton reaction parameters were optimized: pH (7), reaction time (15 h), iron sulfate (2 wt.%), and hydrogen peroxide (10 wt.%). The results indicate that, under the specified conditions, the average diameter of the raw fibers (12.3 ± 0.5 µm) was reduced by 58%, resulting in an average diameter of 5.2 ± 0.3 µm for the treated fibers. We demonstrate that the treated fibers had a lower dye adsorption capacity for methylene blue, consistent with the smoother surface features of the treated fibers over the raw flax fibers. Overall, this study contributes to utilization of the Fenton reaction an efficient oxidation technique for the production of lignocellulose fibers with improved physicochemical properties, such as reduced fiber diameter distribution, in contrast with traditional alkali-based chemical treatment.

Natural plant fiber-reinforced polymer composites (PFRP) have emerged as an environmental-friendly material in the construction industry, but their creep behavior is a critical concern for load-bearing structures. This study investigates the creep behavior of flax fiber-reinforced polymer composites (FFRP) using the time–temperature superposition principle (TTSP). Due to the application of TTSP on the tensile creep behavior of FFRP is not fully understood, three potential methods for calculating the critical parameters during TTSP are compared to obtain an efficient application method to build the creep master curve. A 2,000-h long-term creep test is conducted parallelly on the same sample to validate the accuracy of the creep analysis results. The study proposes an ideal method to determine the key parameters in TTSP, providing valuable insights for the practical application of PFRP in the construction industry. Meanwhile, the research results in this study would be helpful in better understanding the creep behavior of FFRP via short-term accelerated tests.

The goal of the research was to assess the recycling potential of waste high-density polyethylene (HDPE) films taken as reinforcement with natural fibers to fabricate decorative tiles with improved mechanical properties. Initially, the density of the composite was determined. Further, hardness, quasi-mechanical and impact properties were evaluated for the HDPE/natural fiber composite samples by testing the composites tensile, flexural loads and impact. In addition, to evaluate the thermal characteristics of the composite, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) study were performed. Water absorption and sound absorption properties were determined for industry specific applications. Scanning Electron Microscopic analysis (SEM) was performed for analyzing the microstructure and also HDPE matrix and natural fibers bonding exists in the composite. The findings confirmed that adding natural fibers to the HDPE matrix impressively increased both tensile and flexural strengths by up to 25%. The impact strength was also enhanced by up to 38%, whereas the hardness and density values remained relatively unchanged. Improved interfacial bonding between the HDPE matrix and natural fibers had been identified by SEM analysis, which was a factor in the composite material's enhanced mechanical characteristics. These findings suggest that waste HDPE films/natural fibers composite can be effectively recycled to fabricate decorative tiles with improved mechanical properties, thereby offering a sustainable and eco-friendly alternative to traditional decorative tile materials.

Linum usitatissimum commonly known as flax fibers, emerges as a promising reinforcement phase for artificial polymer resins, boasting ecological benefits, low density, and easy accessibility. However, the mechanical behavior of such composites hinges crucially on factors such as fiber mat thickness, nanoTiO2 filler content, and the application of cryogenic treatment. Addressing this complex interplay, this study employs a hand lay-up technique for composite construction, subjecting nanocomposite plates to the challenging liquid nitrogen conditions at 77 K post-manufacture. Recognizing the need for an optimized approach, Response Surface Methodology (RSM) based on Box-Benhken designs is employed to enhance the mixing features of linum usitatissimum polymer composites. The study calculates anticipated mechanical strength values through rigorous ANOVA inferential analysis, uncovering the pivotal roles played by fiber mat thickness, nanofiller content, and cryogenic treatment in the two feature interactions (2FI) model components. The methodology proves robust with high R2 values (0.9670 for tensile, 0.9845 for flexural, and 0.9670 for interlaminar shear strength) consistently aligning with experimental findings. The study culminates in identifying optimized parameters for maximal mechanical properties—300 gsm flax fiber thickness, 5 wt.% nano TiO2 concentration, and a 15-min cryogenic treatment—a result that advances our understanding of fundamental factors influencing composite performance and provides practical guidelines for applications in fields requiring superior mechanical strength in challenging environments.

In fiber metal laminates (FMLs), the order in which fibers with different natural properties are stacked is very important for making materials that absorb vibrations and have good mechanical properties for structural applications. Hence, the present study focuses on the mechanical and vibration characteristics of FML designed with multi‐order energy‐absorbing flax fiber and high‐strength basalt fiber stacking covered with titanium sheets. The fabricated FMLs were designed with titanium/basalt fiber laminate (Ti/B), titanium/flax fiber laminate (Ti/F) and titanium/multi‐order‐flax‐basalt fiber laminate. The mechanical characteristics including tensile, flexural, and impact strength; and vibration characteristics of prepared FMLs were investigated. The higher tensile and flexural strength were revealed in an FML consisting of basalt layers (Ti/B) laminate than the flax core part (Ti/F) due to the strongness of basalt fiber, increasing the capability of load‐bearing of composites. Ti/B FML showed a maximum tensile strength and flexural strength of 412 and 450 MPa. Furthermore, flax fiber absorbs more energy, so the flax layer's inbuilt structure increases energy absorption during impact and vibration testing. Ti/F exhibits the highest impact strength (427.8 kJ/m2) and Ti/B exhibits the lowest impact strength (312.5 kJ/m2) because flax fibers are more ductile than basalt fibers, increasing the toughness of the FML. Ti/F FML structure, the greatest natural frequency of modes 1, 2, and 3 (549.03, 715.07, and 956.15 Hz) was observed. Natural fiber hybridization designed for FML, such as the Ti/B/F laminate, improved mechanical and vibration properties, making it suitable for structural applications. Highlights: Fiber metal laminates were designed with titanium/flax/basalt.FMLs stacked composites significantly affect the mechanical properties.The basalt fiber, increases the capability of load‐bearing of FMLs.The damping of FMLs increases with the increase in flax fiber layers.Flax‐basalt fibers stacked FMLs produce tunable impact and vibration energy. [ABSTRACT FROM AUTHOR]

Natural fibre-reinforced polymer composites, recently developed, provide several socioeconomic and sustainability benefits for a wide range of technical applications. The purpose of this study was to look at how natural flax fibre (30 wt%) and silicon dioxide (SiO2 (0, 2.5, 5, 7.5, 10, 12.5 wt%)) affect ternary mixes' mechanical, combustible, and water absorption qualities. A cone calorimetry investigation revealed that the inclusion of nanosilicon dioxide might reduce the polypropylene (PP) composites made from flax fibre's total heat release, total smoke release, and heat release rate. Using 10 wt% nanosilicon dioxide, the heat release rate (255 kW/m2 to 161 kW/m2) was considerably reduced. The mechanical characteristics of the composites increased with the addition of nanosilicon dioxide, and the flexural (50.97 MPa) and tensile strength (42.65 MPa) of the materials reached their maximum values at 10 weight% nanosilicon dioxide. Nanosilicon dioxide exhibited homogeneous dispersal in the flax fibre-based PP composites, with an increase in nanosilicon dioxide from 2.5 to 10 wt%, according to scanning electron microscopy observations on the fractured portion of the hybrids. The lack of a recognisable peak in the X-ray diffraction (XRD) after the integration of nano-SiO2 particles suggests that the granules were homogeneous. The highest water absorption in flax/PP hybrids decreases by 13.25, 15.69, 20.16, 23.63 and 19.52% as compared to pure PP and PP with flax fibre with the addition of 2.5, 5, 7.5, 10 and 12.5 wt% of SiO2 filler, respectively. Based on the obtained results in natural flax fibre-based hybrid composites, the nanoSiO2 particles worked as barriers to prevent moisture absorption and increase their rigidity. These outcomes imply that such materials would be appropriate for use in moist settings, like those seen in the maritime, outdoor, and packaging sectors. Additionally, these results imply that such composites may find use in sectors where fire safety is a top priority. [ABSTRACT FROM AUTHOR]