Search

Polymer composite materials are widely used in diverse applications, prompting an ongoing quest to improve their performance. Coconut husk char, derived from agricultural waste, can be utilized as a filler or reinforcement in the composite. The char can provide additional strength and stiffness to the composite while enhancing its sustainability. Coconut husk char is abundant, low-cost, and renewable, making it as an attractive eco-friendly additive. This paper shows the incorporation of coconut husk char filler in flax fiber/vinyl ester hybrid composite at varying percentages (5, 10, 15, and 20 wt%). Mechanical tests were conducted to assess tensile, flexural, impact, and hardness properties. Upon the addition of 10 wt% char, maximum tensile strength of 46 MPa, hardness of 89, and impact strength of 36 J/m were achieved. There was a decrement in strength after 10 wt% due to poor interface development and char particle agglomeration. These results substantiated the efficacy of the ash filler in the development of the composite, potentially paving the way for further advancements in composite materials and offering valuable insights into the optimization of mechanical properties through innovative filler combinations. [ABSTRACT FROM AUTHOR]

In the present study, the effect of moisture absorption on the properties of jute/flax-reinforced epoxy composite with coconut shell powder and eggshell powder as nanofillers was investigated. The nanocomposite samples were immersed in water for 6 months then they were tested for various mechanical properties in accordance with ASTM or ISO standards. Scanning electron microscopy (SEM) was used to identify the potential cause of failure of the specimen after mechanical tests. From the experimentations, it was found that jute/epoxy/coconuts shell powder, jute/epoxy/eggshell, flax/epoxy/coconut shell, and flax/epoxy/eggshell showed a reduction in their tensile strength of 29.29%, 24.89%, 20.17%, and 21.56% respectively. They also showed reduced flexural strength of 19.72%, 18.46%, 22.63%, and 19.06% respectively. Similarly, jute/epoxy/coconuts shell powder, jute/epoxy/eggshell, flax/epoxy/coconut shell, and flax/epoxy/eggshell showed a reduction in their impact strength of 11.35%, 6.88%, 9.25%, and 8.57% respectively. But water immersion showed a positive result on the surface roughness of the nanocomposite as the surface roughness of jute/epoxy/coconut shell and jute/epoxy/eggshell slightly improved by 12.5% and 14.28% respectively. Morphological analysis using SEM demonstrated fiber pullout, debonding, and voids due to moisture uptake which are responsible for weak interfacial adhesion between fiber and matrix which affects the overall performance of developed nanocomposites. [ABSTRACT FROM AUTHOR]

This work investigates the influence of crystallinity on the mechanical properties of needle-punched non-woven flax/polylactic acid (PLA) biocomposites with different flax fiber contents. Biocomposites were fabricated by a compression molding adopting different cooling rates to understand the mechanism of crystallinity and their contribution to the mechanical properties. Image-based analysis of the fiber distribution in non-woven preform indicates the probable origins of the residual porosities and the potential nucleation sites for crystal formation within the composites. The improvement of 25% and 100% in flexural modulus is observed for the composites with 40% and 50% of flax fiber mass fractions, respectively, when subjected to a lower cooling rate, which implies the significant influence of the void content on the brittleness of composites. The impact properties of the composites decrease from 11% to 18% according to the flax fiber mass fraction when the cooling rate decreases to 1 °C/min, and the composites become more brittle. The induced impact and flexural properties of the composites are compared with those of other composites in the literature to emphasize their applicability to semi-structural applications. [ABSTRACT FROM AUTHOR]

The scenario of modern technology adopting polymer-based hybrid composites is caused by specific properties like high strength, lower specific weight, and improved toughness. Besides, the natural fiber-made polymer composite faced inconsistent behaviour, moisture absorption, and processing challenges that limit their utilization for high-performance usages. The current investigation on polypropylene (PP) composite composition of 2-4 mm sodium hydroxide surface-treated flax fiber (TFF) and nano-sized (50 nm) alumina particles (Al2O3) by using injection moulding, which is 10 wt% flax fiber along with 0, 2.5, 5, and 7.5 wt% nano-sized Al2O3 to enhancing the behaviour of mechanical strength and evaluation of such as yield/tensile, impact, and flexural strength of the composite. During the fabrication process, an injection pressure of 100 MPa is applied at a processing temperature of 200 °C for 10 min. The contributions of Al2O3 and TFF to the polypropylene (PP) matrix are examined using transmission electron microscopy (TEM) analysis. The TEM results reveal a homogeneous structure with a uniform distribution of TFF and Al2O3. The optimal mechanical properties are observed in the composite of PP with 10 wt% TFF and 7.5 wt% Al2O3, which shows superior performance compared to other compositions. The yield strength/tensile strength, impact strength, and flexural strength of the PP/10 wt% TFF/7.5 wt% Al2O3 composite are measured to be 42.8 ± 0.6 MPa/49.5 ± 0.7 MPa, 18 ± 0.8 J/mm2, and 56 ± 0.6 MPa, respectively. This particular composition of composite specimens is recommended for applications in automobile cabins. [ABSTRACT FROM AUTHOR]

Composite sandwich structures composed of artificial materials are widely used. However, manufacturing artificial materials requires extensive energy and significantly impact our environment. Therefore, there is a growing focus on manufacturing composites using natural materials. This study used flax fabric, cotton fabric, glass fiber fabric, and polylactic acid (PLA) to fabricate the facesheets of sandwich beams, with balsa panels used as the cores. Tensile, flexure, tensile-after-impact (TAI), and flexure-after-impact (FAI) tests were conducted on the constituent materials and the sandwich beams. As expected, glass fiber reinforced PLA (GFRP) exhibited the highest tensile, flexural, and TAI properties compared to flax fiber reinforced PLA (FFRP) and cotton fiber reinforced PLA (CoFRP) and contributed to the highest FAI strengths in the sandwich beams using GFRP facesheets. It was also observed that a stiffer facesheet resulted in more core crushing in its sandwich beams when subjected to FAI tests, while a weaker facesheet led to more debonding in its sandwich beams. Since sustainable natural materials have been attracting research interest and are used in various areas, this work contributes to using natural composite materials and sustainable development. [ABSTRACT FROM AUTHOR]

Flax Fibers (FF) and Ramie Fibers (RF), with equal holo-cellulose contents (approx. 87%), have been used in equal proportions as reinforcements to develop their Chemically Functionalized Polypropylene (CF-PP) hybrid composites: [5/5]/90, [10/10]/80 and [15/15]/70 [FF/RF]/CF-PP hybrid composites. These hybrid composites, developed by extrusion followed by injection molding, exhibit good adhesion of FF and RF with CF-PP, as evident in their FE-SEM micrographs. FTIR establishes this adhesion originating from ester bonds and hydrogen bonds, formed between the reinforcements and the matrix by Palsule process. These [FF/RF]/CF-PP hybrid composites display higher tensile, flexural and impact properties than their matrix, and the property values increase proportionally with the total reinforcement content in the hybrid composites. Of all the hybrid composites, the [15/15]/70 [FF/RF]/CF-PP composite exhibits the highest mechanical properties, likely due to the highest total reinforcement content. Water absorption by the composites increases with the reinforcement content, and the [15/15]/70 composition shows the highest water uptake. Relative to the synthetic and inorganic fiber based composites, these [FF/RF]/CF-PP hybrid composites offer relatively better life cycle assessment parameters and higher sustainability with potential for reduced adverse impacts of environmental and energy during their manufacturing and applications. [ABSTRACT FROM AUTHOR]

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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. Highlights: 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 epoxy hybrid nanocomposite is prepared with 15 wt% of flax fiber (FF) and 1-5wt% of boron carbide nanoparticle (B4C) through a compression moulding process. Before the fabrication, the FF surface is treated with a 5% concentration sodium hydroxide solution to enhance fiber quality and reduce moisture absorption. The impact of FF and B4C on the flexural, impact, and hardness properties of the composites is evaluated and compared with an epoxy/15wt% FF composite sample. The flexural, impact, and hardness of composite samples (epoxy/15wt% FF, epoxy/15wt% FF/1 wt% B4C, 3wt% B4C, and 5wt% B4C) show significant enhancement. For instance, the flexural and impact strength varies 48.5, 53.5, 58.6 & 65.6 MPa for flexural strength and 3.6, 4.1, 4.8 & 5.3 J/mm2 for impact strength. Similarly, the composite sample's hardness demonstrates a remarkable improvement of 32.5, 35.6, 41.6, & 46.7 HV with increasing B4C content (0, 1, 3, & 5 wt%) in epoxy/15wt% FF. The epoxy hybrid nanocomposite comprising 15wt% HF and 5wt% B4C achieves the optimal values. The flexural and impact failure is analyzed using scanning electron microscopy, revealing interfacial debonding and matrix cracking failures. This composition is used in automotive cabinet applications. [ABSTRACT FROM AUTHOR]

The goal of this study is to compare the tensile strength of novel teakwood dust with a unique flax fibre composite. Group 1 was the control group in this study, while Group 2 was the experimental group, which included flax fibre composite and teakwood with flax fibre composite. Each group had a sample size of 20, for a total sample size of 40. G power was kept at 80% for estimating sample size. Tensile strength of the 10(Wt.%) novel teakwood dust with flax fibre composite was 39.1287 MPa, and the flax fibre composite's tensile strength was 20.0280 MPa, as per the experimental results. A statistically significant difference (p = 0.005; p < 0.05) has been observed in the flax fibre composite. The two groups' differences are statistically significant. The 10(Wt.%) teakwood dust with flax fibre composite has a higher tensile strength than the flax fibre composite, according to the experiment's findings. The results show that the composite with flax fibre and teakwood dust reinforcement has a greater tensile strength and is more sustainable than flax fibre composites. [ABSTRACT FROM AUTHOR]

This study investigates the flexural behavior of three sandwich panels composed of an agglomerated cork core and skins made up of cross-ply [0,90]2 flax or glass layers with areal densities of 100 and 300 g/m2. They are designated by SF100, SF300, and SG300, where S, F, and G stand for sandwich material, flax fiber, and glass fiber, respectively. The three sandwich materials were fabricated in a single step using vacuum infusion with the liquid thermoplastic resin Elium®. Specimens of these sandwich materials were subjected to three-point bending tests at five span lengths (80, 100, 150, 200, and 250 mm). Each specimen was equipped with two piezoelectric sensors to record acoustic activity during the bending, facilitating the identification of the main damage mechanisms leading to flexural failure. The acoustic signals were analyzed to first track the initiation and propagation of damage and, second, to correlate these signals with the mechanical behavior of the sandwich materials. The obtained results indicate that SF300 exhibits 60% and 49% higher flexural and shear stiffness, respectively, than SG300. Moreover, a comparison of the specific mechanical properties reveals that SF300 offers the best compromise in terms of the flexural properties. Moreover, the acoustic emission (AE) analysis allowed the identification of the main damage mechanisms, including matrix cracking, fiber failure, fiber/matrix, and core/skin debonding, as well as their chronology during the flexural tests. Three-dimensional micro-tomography reconstructions and scanning electron microscope (SEM) observations were performed to confirm the identified damage mechanisms. Finally, a correlation between these observations and the AE signals is proposed to classify the damage mechanisms according to their corresponding amplitude ranges. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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]

Copyright of Journal of Donghua University (Natural Science Edition) is the property of Journal of Donghua University (Natural Science) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Flax fibers are a viable material for creating sustainable composites since they have mechanical qualities similar to those of synthetic fibers. Because of their unique hydrophilicity and strong mechanical properties, flax fibers should be taken into specific attention while creating composite materials. Vegetable fibers like flax are highly versatile and are frequently utilized in structural composites. Additionally, flax has shown potential in a variety of other uses, including as shipping, automotive, aerospace, and construction. This study aims to provide a comprehensive overview of the state of advancement in flax fiber reinforcement composite research. The most important research on thermoset and thermoplastic composites reinforced with flax fiber is compiled and analyzed in this article. This article also summarizes the main properties of flax fibers, discusses chemically enhancing their qualities, explains the process of making and analyzing flax fiber composites, and identifies areas that require more research. The article concludes with a few critical ideas and future directions that emphasize the challenges that need to be handled in more in‐depth research and probable composites industrialization. Highlights Flax fibers: Structure, composition, and extraction techniques explored. Polymer matrices in flax fiber composites: Types and processing methods. Mechanical properties of thermoset and thermoplastic flax fiber reinforced composites. Applications of flax fiber composites in automotive, construction, and aerospace. Future potential of flax fiber and hybrid composites in advanced materials.

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]

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]

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]

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.

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.

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.

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]

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]

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]

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]