Bio-based materials are a relevant alternative to traditional building materials particularly due to their carbon sequestration and storage properties. However, their high flammability limits their use and the application of a fireproof treatment is needed. Since fireproof treatments may alter the fibers, and the acoustic properties depend on the material’s microstructure, it is essential to evaluate the impact of such treatments. The goal of this paper is to evaluate the performance of hemp fibers, before and after fireproof treatment. Also, it aims to understand the impact that it can have on their microstructure using acoustic parameters. The sound absorption of four treated formulations and one untreated reference configuration was evaluated with an impedance tube using a three microphones characterization method. This method allows the indirect determination of the characteristic parameters of the pore network within the samples using equivalent fluid modeling. In addition, the use of homogenization models such as Tarnow’s enables the estimation of the effective radius of the fibers in the samples. Thus, an increase in fiber radius was observed after fireproof treatment, providing a possible explanation for the experimentally observed decrease in airflow resistivity and viscous dissipative effects, as well as the reduction in acoustic absorption in the treated hemp fiber stacks. • Evaluation of the impact of a flame-retardant treatment based on phytic acid and urea on the sound absorption performance of hemp fiber stacks. • The sound absorption of flame-retardant hemp fibers was assessed with an impedance tube with a three microphones configuration. • The characteristic parameters of the pore geometry were indirectly obtained and compared between untreated and treated samples. • Small reduction in sound absorption performance, airflow resistivity and viscous dissipative effects was observed in treated hemp fibers. • Based on the Tarnow model, an increase in the estimated fiber radius was observed in the treated samples, indicating an impact of the treatment in the microstructure of the hemp fibers.

Printability versus durability in 3D-printed biocomposites: Unraveling the distinct roles of flax and hemp fibers in PLA-based filaments

This study investigates the influence of sodium hydroxide (NaOH) surface treatment on the out-of-plane auxetic behavior and mechanical properties of hemp/polylactic acid (PLA) nonwoven composites. Untreated and alkali-treated hemp fibers (2.5 wt.%, 5 wt.%, and 7.5 wt.% NaOH) were used to fabricate needle-punched nonwovens with 50 wt.% PLA. Scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR) were employed to analyze surface morphology, thermal stability, and chemical changes, respectively. Alkali treatment effectively removed hemicellulose and lignin, enhanced surface roughness, and improved fiber matrix adhesion. Mechanical testing revealed that 5 wt.% NaOH treatment yielded the highest tensile strength due to optimal interfacial bonding and mechanical interlocking. However, out-of-plane Poisson's ratio measurements indicated a decrease in auxetic magnitude with increasing NaOH concentration, with the maximum negative Poisson's ratio of approximately −6.5 observed for untreated composites and −2.3 for treated ones. The results demonstrate that improved interfacial bonding enhances strength but restricts fiber rotation and reorientation, leading to reduced auxetic behavior. This work establishes a direct correlation between fiber surface modification and auxetic tunability, providing valuable insight into designing sustainable, functionally adaptive composites for structural and protective applications.

Sustainable structural composites can significantly lower vehicle-related emissions. To evaluate the recycling of different composite materials, laboratory-scale pyrolysis was conducted and assessed both technically and environmentally. Two demonstrators were studied: a truck side skirt made from natural flax and hemp fibres with polypropylene (PP), and a car front header composed of glass fibres and PP. Additional materials examined included thermoplastic composites containing polyamide 6 (PA6), bio-based polyamide 11 (PA11) and thermoset polyester. Results showed that material type strongly influenced the pyrolysis outcome, product composition and recycling potential. Glass fibres could be recovered and reused as reinforced fibres, while natural fibres could be recovered as biooil for potential use in biofuel production. Polymers were recovered as pyrolysis products that, depending on their composition, can be used in different applications, from recovering monomers from PA6 to producing hydrocarbons that may replace naphtha (from PP) or aromatics (from polyester) in the petrochemical industry. Life cycle assessment (LCA) findings revealed that the climate impact of composite recycling is primarily driven by the environmental burdens of the recycling process itself and by the ability of recovered materials and chemicals to substitute conventional fossil-based alternatives. Efficient recycling pathways are therefore essential to maximising environmental benefits.

ABSTRACT The phenomenon of textiles attached to the surface of oracle bones has attracted the attention of the academic community since 1975, but there has always been a technical bottleneck and academic controversy in the identification of its fiber types. Taking the textile fibers attached to six oracle bones in the collection of Huan Bao Zhai as the research object, the microstructure of the residual textiles was observed by means of super depth‐of‐field microanalysis. Combined with Field Emission Scanning Electron Microscopy (FE‐SEM) to understand the characteristics of fiber morphology, and while comparing modern silk, cotton, kapok, and hemp fibers, it was determined that the fiber attached to the oracle bone of the Shang dynasty is hemp and ramie fibers. This suggests that the Shang dynasty would have used bast‐fiber ropes binding the oracle bones for storage. This kind of rope might be “Sacrificial cloth” offered to the spirits. The study fills a missing link in the ancient literature about the divination process of oracle bones and provides a useful supplement to the study of ancient Chinese historical materials.

Abstract In recent times, an increasing demand for the need of biodegradable alternatives has emerged in the Additive Manufacturing Industry. Therefore, this research aims to develop a hybrid bio composites polymers using a fabrication method called Micro Injection Molding (MIM). In this research, Hemp fiber and a variant of Agave fiber which is called as Sisal Fiber are used. To address the limitation of natural fiber properties, the fibers were initially subjected to alkali (NaOH) treatment. Thereafter, they were both oven-dried and sun-dried until they were ready to be ground and milled. They were milled up to a size fraction of 200-250 μm. Three composite formulations were prepared, maintaining a total fiber loading of 10 wt.% of fibers along with 90 wt.% of PLA (Poly Lactic Acid). The composition percentages were 5% Hemp and 5% Sisal for the 1st sample (H5S5); 7.5%-Hemp and 2.5%-Sisal for the 2nd sample (H7S3) and 2.5%-Hemp and 7.5%-Sisal for the 3rd sample (H3S7). Among the three compositions, the H7S3 formulation exhibited the highest tensile strength of 53.19 MPa and a flexural strength of 83.24 MPa, in addition to an impact energy of 0.90 J, indicating successful fiber reinforcement and load distribution within the PLA matrix. The load–displacement and stress–strain behaviors demonstrated enhanced stiffness and improved load-bearing capacity in the hybrid composites. Measurements of water absorption revealed minimal weight changes during the testing period. Flame testing indicated a delayed ignition time with self-extinguishing properties, absence of melt dropping, and the formation of surface char. SEM analysis of tensile-fractured specimens showed uniform fiber distribution, fiber breakage, and crack deflection characteristics at the fiber–matrix interface. These results demonstrate the potential of hemp-sisal hybrid reinforced PLA composites for sustainable additive manufacturing applications.

Upcycling of industrial hemp byproducts into a sustainable molded fiber packaging system.

Modified burn-off method for fiber content assessment in hemp and flax reinforced composites for marine structural applications

Integrated TiO2/CQDs photocatalytic and enzymatic pretreatment of hemp fibers under mild conditions for sustainable processing

Impact of hemp fiber content and length on the hygrothermal, mechanical, and CO2 emission performance of hemp-lime composites

Abstract This study investigates the development and mechanical characterization of epoxy composites reinforced with Crotalaria juncea (sunn hemp) fibres and naturally extracted cellulose filler. Physical properties including density, water absorption, and thickness swelling were also evaluated to gauge suitability for medium-density fiberboard (MDF) applications. Composite laminates were fabricated using different fibre volume fractions (20, 25, 30, and 35 vol. %) and cellulose filler contents (5, 7.5, and 10 vol. %) to evaluate their influence on mechanical performance. Tensile, flexural, impact, and hardness properties were examined in accordance with ASTM standards. The tensile strength of the composites varied from 18.12 MPa to 39.07 MPa, while flexural strength ranged between 29.52 MPa and 74.56 MPa. Impact energy absorption values were found to be in the range of 1.1 J to 2.7 J, and Shore D hardness values ranged from 75.63 to 89.18. The composite containing 30 vol. % fibre and 7.5 vol. % cellulose filler exhibited the most favorable mechanical performance among the investigated compositions. Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD) analyses were carried out to study chemical interactions and crystalline characteristics, while Scanning Electron Microscopy (SEM) was used to examine fracture surface morphology. Tests of thermal stability (TGA) were performed to assess decomposition behavior. The results demonstrate that appropriate cellulose filler incorporation improves fibre–matrix interaction and mechanical behaviour. The developed composites show potential for interior and structural applications where sustainable materials are required.

Socks are among the fundamental items of clothing widely used in sports and outdoor activities. The wide scale usage demands socks with enhanced comfort and functional properties. Research is now focused on the development of sustainable textiles using alternative fibers with multifunctionality and balanced comfort addressing the consumer demand. This study aims at the development of multifunctional socks using three different bast fibers i.e. banana, flax & hemp blended with cotton fibers in three different blend percentages of 10:90, 20:80 and 30:70. 100% cotton fiber sample was used as control. Physical, mechanical, comfort, antibacterial and ultraviolet protection properties of the samples were evaluated to investigate the effect of fiber type and blend percentage on the final performance. There is significant effect of the type of fiber on the properties of developed socks, for example, flax fibers blended socks exhibited better strength than all other samples beside higher air permeability. Banana fibers blended socks exhibited better moisture management and ultraviolet protection. Hemp fibers blended socks exhibited better abrasion resistance. Regarding the effect of blend percentage, it was found that 10% & 20% blend of bast fibers demonstrated better properties as a whole increasing their percentage shows some intricate results. Antibacterial performance was qualitatively evaluated using parallel streak method. Blended samples demonstrated better properties as compared to the control samples which advocate the use of alternative fibers to enhance the properties. Results were statistically analyzed to evaluate the reliability and significance of results using ANOVA analysis and multi-response optimization was done using Taguchi grey relational analysis and then the samples were ranked accordingly. The sample with 10% banana fibers was ranked as 1st, following the sample with 10% flax fibers as second and then 20% banana fibers as the third.

This paper presents a laboratory study of the effect of naturals (hemp fibers) and synthetics fibers (glass fibers) on the mechanical behavior of sandy soil (natural Chlef sand). A series of shear direct tests were carried out on medium dense (RD= 50%) and dense (RD= 80%) Chlef samples sand with different naturals and synthetics content fibers ranging from 0, 0.25, 0.5, 0.75 and 1% and under three normal stress of 50, 100 and 200 kPa. The test results show that the addition of fibers has a significant effect on the shear strength of the sand-fiber mixture, however, this shear strength increases with the increase of the fibers content, the normal stress applied and the relative density until up an optimal fibers content of 0.5% for the glass fibers and 0.75% for the hemp fibres. Beyond these optimal fibres content, the shear strength decreases. The internal friction angle and the cohesion are significantly influenced by the fibres content.

This study investigates the two-body abrasive wear characteristics of hybrid hemp and bamboo fibers in woven form epoxy (H/B F-Ep) composites reinforced with micro-crystalline cellulose (MCC) using a response surface methodology (RSM) framework and microstructural analysis. The effects of MCC content, emery paper grit, load, and abrading distance, on weight loss, coefficient of friction (CoF), and surface roughness (Ra) were assessed using four factors and three levels using Box–Behnken design. Analysis of variance (ANOVA) was used to develop and statistically validate quadratic regression models, which demonstrated strong predictive ability, a non-significant lack-of-fit, and high coefficients of determination (R² = 95.84–97.06%). Emery paper grit and abrading distance dominate wear loss, MCC content controls frictional response, and both MCC and grit have a substantial impact on surface roughness, according to an ANOVA. Strong nonlinear wear behavior under severe abrasion is indicated by significant interaction and quadratic terms, especially grit2 and filler–grit coupling. Optimized MCC loading reduces micro-cutting and stabilizes tribo-layer development, as indicated by main-effects and interaction plots. The statistical results were supported by SEM measurements, which showed a shift from severe micro-ploughing and fiber pull-out in unfilled composites to moderate abrasion and compacted tribo-films at the optimal MCC content. To minimize wear loss (0.0385 g), CoF (0.27), and Ra (1.62 μm), with an overall desirability of 0.96, multi-response desirability optimization determined that 3 wt% MCC, 400-grit abrasive, 150 m abrading distance, and 10 N load were the optimal settings. A strong framework for customizing natural fiber hybrid composites for tribological applications is provided by the combined RSM–SEM technique.

In this study, lightweight geopolymer mortars with low environmental impact, high thermal insulation performance, and strong resistance to elevated temperatures were developed. Fly ash, expanded perlite, and bio-based hemp fibers were employed as the binder, aggregate, and reinforcement, respectively. Hemp fibers were prepared in lengths of 1, 2, and 3 cm and incorporated into the mixtures at dosages of 0.50%, 0.75%, and 1.00% by weight of binder. Sodium hydroxide was used as the activator, and specimens were heat-cured at 90 °C for 24-48-72 h. The workability, unit weight, UPV, flexural, and compressive strength of the geopolymer mortars were determined. In addition, thermal conductivity, high-temperature resistance, microstructural characteristics, and environmental impacts of selected mixtures were evaluated. The results demonstrated that lightweight geopolymer mortars could be successfully produced using expanded perlite aggregate and that hemp fibers significantly enhanced mechanical performance up to 48% at one day. Moreover, fiber reinforcement improved thermal insulation capability by up to 5.5% and high-temperature resistance. FESEM, EDX, elemental mapping, and XRD analyses supported the mechanical and physical findings through detailed microstructural evidence. Furthermore, LCA results revealed that fiber incorporation improved the environmental performance of geopolymer mortars, resulting in approximately a 21% reduction in global warming potential compared with the reference mixture.

This study evaluates the feasibility of upcycling cellulose-based industrial textile wastes as reinforcement materials in recycled paper production. Waste cotton, flax, and hemp fibers were incorporated into recycled paper pulp at weight ratios of 25, 50, and 75 wt% to examine their effects on the physical and mechanical properties of handmade papers. Physical properties (basis weight, thickness, and water absorption) and mechanical performance (tensile index and tensile energy absorption index) were characterized. The results showed that textile fiber reinforcement significantly improved the mechanical performance of recycled papers. Cotton-reinforced papers exhibited increasing tensile strength and energy absorption with higher fiber content, whereas flax- and hemp-reinforced papers achieved maximum strength at lower fiber ratios. The highest tensile index (49.08 Nm/g) and tensile energy absorption index (3.11 J/g) were achieved with 75 wt% cotton fiber reinforcement. Water absorption behavior was strongly influenced by fiber type and crystallinity, showing an inverse relationship with mechanical performance. The findings demonstrated that cellulose-rich textile waste can serve as a sustainable reinforcement for recycled paper, supporting circular material use between the textile and paper industries and enabling applications in art, packaging, and value-added paper products.

The impact of microcrystalline cellulose (MCC) on the mechanical, physicochemical, and tribological properties of hemp fabric–reinforced epoxy (HF/Ep) hybrid composites is examined in this work. Different MCC contents were used to construct the composites (0 wt% (M0), 3 wt% (M1), 6 wt% (M2), and 9 wt% (M3)). Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), hardness, impact strength, and three-body abrasive wear testing were used to assess the impacts of MCC integration. The results showed that MCC greatly improved the composites’ toughness and hardness, with impact strength improving by about 83% and Shore D hardness rising from 83 (M0) to 89 (M3). While XRD patterns showed increased crystallinity with increasing MCC content, FTIR examination verified enhanced interfacial contacts between the MCC, hemp fibers, and epoxy matrix. Wear loss was significantly reduced in three-body abrasive wear tests, especially for the M2 composition, which reached a maximum reduction of about 68.6% under extreme loading conditions. Increased surface hardness, greater load transfer, efficient crack deflection, and the development of a protective tribolayer during abrasion were all identified as contributing factors to the improved wear performance. These findings show that the structure-property-wear correlations of HF/Ep composites may be successfully tailored by controlled MCC incorporation, making them appropriate for wear-resistant, lightweight engineering applications.

Abstract Resonance is a critical phenomenon in structural dynamics, occurring when a structure’s natural frequency coincides with an external excitation frequency, resulting in amplified vibrations and increased deflection that may lead to structural failure. Mitigating resonance requires a thorough understanding of the structure’s dynamic properties and the application of effective damping techniques. This study experimentally investigates the dynamic behaviour of a composite beam composed of a polymer matrix (70% polyester resin and 30% vinyl ester resin) reinforced with carbon and hemp fibers. To enhance vibration damping, elastomeric materials, such as neoprene and silicone rubber, are incorporated. The results indicate that carbon fiber reinforcement yields higher stiffness and natural frequency. In contrast, hemp fiber exhibits a superior damping ratio. Neoprene rubber contributes to increased structural stiffness, while silicone rubber demonstrates enhanced damping performance due to its viscoelastic characteristics. The appropriate selection of fiber reinforcement and the addition of elastomeric material to composite materials make them more effective in shifting the natural frequency and reducing the response amplitude. The selection of fiber-elastomer combinations is guided by specific design objectives: carbon fiber with neoprene rubber is suitable for applications requiring higher stiffness conversely, hemp fiber combined with silicone rubber is recommended for improved damping.

Waste fibers generated during hemp fiber processing (hemp noil) are often disposed of as solid waste due to inadequate treatment technologies, causing resource waste and failing to meet the demand for high-quality fibers in yarn production. To achieve efficient recovery and high-value utilization of hemp noil, and explore a green refined process suitable for yarn production, this study uses hemp noil as raw material and proposes a green refining process: polyethylene glycol/water pretreatment, composite enzyme degumming, and sodium percarbonate bleaching. The optimal conditions are: polyethylene glycol/water mass ratio 0.2:1, bath ratio 1:50, treatment at 25 ℃ for 60 min. Results show the contents of reducing sugar, total sugar, free phenolic hydroxyl groups in the solution, and fiber whiteness are 71.06%, 23.66%, 39.49%, and 33.25% respectively, achieving the optimal overall effect—an increase of more than 30% compared with the traditional chemical pretreatment process (whiteness 22%-25%). The degummed cotton-type industrial hemp fibers have a breaking strength of 10.73 cN and fineness of 0.28 tex, significantly superior to single-enzyme degummed products (fineness > 0.4 tex, strength > 7 cN). The response surface optimization results are reasonable and feasible. Blended with cotton at 70/30 ratio on cotton spinning equipment, the blended yarn exhibits an evenness CV value of 16.59%, breaking force of 315 cN, and breaking strength of 9.2 cN/dtex, 22.7% higher than pure hemp yarn (7.5 cN/dtex), indicating good spinnability. This environmentally friendly process provides a green solution for the refined processing of industrial hemp fibers. • Recycling and Utilization of Industrial Waste Fibers. • Green Degumming Process for Hemp Fibers. • High-performance hemp-cotton blended yarn via cotton spinning.

Although natural and recycled fibre-based insulation materials show promising thermal and acoustic performance, several challenges still limit their widespread adoption. This paper explores the properties and potential of recycled textile and natural fiber-based materials in enhancing building renovations. Specifically, it examines two types of insulation panels: those made from recycled textiles (Panels M) and those composed of kenaf and hemp fibers (Panels K). The study investigates various properties, including composition, density, thermal conductivity, acoustic performance, and fire response, highlighting the strengths and challenges associated with each material. The results reveal that while textile-based panels exhibit more variability in composition and performance, natural fiber panels are more uniform, making them a more predictable and reliable option. Thermal conductivity values ranged from 0.035 to 0.049 W/(m·K), with the natural fiber panels showing more consistent results. Acoustic performance, evaluated using both Sonocat sensor and the impedance tube also varied, with textile-based panel M45 performing particularly well approaching the Basotect performance (this latter used as a functional benchmark). Fire response, tested using Temperature Programmed Oxidation (TPO), indicated that kenaf-based panels demonstrated higher flammability compared to their textile counterparts. Furthermore, the study explored the effectiveness of fire retardants, finding that certain treatments helped suppress ignition.