Papers by Keyword: Hemp Fiber

Abstract: Natural fibre composites are gaining importance in engineering and automotive sectors due to their sustainability, lightweight nature, and cost-effectiveness. However, their flexural modulus and other mechanical properties require enhancement to meet industrial standards. This study aims to improve the performance of hybrid composites reinforced with hemp, jute, and coir fibres in an epoxy matrix. Specimens were fabricated using the hand lay-up technique followed by compression moulding and tested according to ASTM standards. Mechanical characterization included hardness, tensile, flexural, compressive, and impact tests, along with water absorption analysis. The results demonstrated significant improvements, with maximum hardness of 80 HRM, tensile strength of 16.95 N/mm², compressive strength of 5.268 N/mm², flexural strength of 95.96 N/mm², and impact resistance of 0.20 J. Water absorption varied between 11.6% and 25%, depending on resin-to-fibre ratios. One-way ANOVA confirmed statistically significant differences among formulations (p = 0.005), validating the effect of fibre–resin composition. The optimal formulation (75% epoxy with balanced fibre reinforcement) achieved superior mechanical performance, establishing hybrid natural fibre composites as a promising eco-friendly alternative to conventional materials.

Abstract: This study investigates the mechanical properties, water absorption and microstructural analysis of hybrid composites reinforced with Hemp fiber (HF) and Sisal fiber (SF) combined with Silicon Carbide (SiC) particles in epoxy composites. The fibers were treated with 5% NaOH solution for varying durations to enhance their properties. Composite laminates were fabricated using compression molding with different weight fractions of fibers (30 wt%) and SiC particles. The mechanical behaviour of the composites was evaluated through tensile, flexural, and water absorption tests following ASTM standards. The results shows that hybridization with hemp and sisal fibers improves the properties of epoxy composites, with increased hemp fiber content leading to enhanced mechanical performance.These included a tensile strength of 57.82 MPa, flexural strength of 94.7 MPa. The water absorption dipped in 120 hours of immersion in water, with the HFSF/SiC-5 showing the highest water absorption of 6%.The SEM images revealed a homogeneous distribution, fiber pullouts, voids of fibers and filler materials confirmed the presence in the composites.

Abstract: This study investigates the mechanical and low-velocity impact properties of 3D-printed Polyamide 12 (PA12) composites reinforced with randomly oriented hemp fibers. Hemp fiber was incorporated at varying weight percentages (4%, 6%, 8%, 10%, and 12%) within the PA12 matrix. Compression molding at 185°C and 4000 psi was used to fabricate composite samples. Tensile testing, drop weight impact analysis, hardness measurement, and scanning electron microscopy (SEM) were conducted to characterize the mechanical behavior of the composites. Results demonstrate that the incorporation of hemp fibers significantly enhances the tensile properties of the PA12 matrix. Composites containing 6% hemp exhibited the highest tensile strength compared to neat PA12. Further increasing the hemp fiber content up to 10% maintained comparable tensile properties to the 6% composite.

Abstract: The use of hemp fiber is capable of increasing the compressive and tensile strength, along with enhanced ductility in concrete. Shell ash also contains calcium compounds that improve the properties of concrete. Therefore, this study aimed to measure the compressive and tensile strengths of concrete as well as the chemical functional groups of hemp fiber. To achieve this, hemp fiber (additive) and 6% shell ash (filler) were added to the concrete mixture, targeting a design strength of 25MPa. The results showed that the average compressive strength of concrete after 28 days obtained a minimum value of 25.668MPa with 0.5% fiber and the maximum strength was 33.446MPa with 1.5% fiber. The split tensile strength test of the concrete after 28 days obtained a minimum value of 1.982MPa, and a maximum of 2.831MPa. These results showed that adding hemp fiber at approximately 1.5% to concrete improved the compressive strength by 4.74% and the split tensile strength by 3.47% compared to conventional concrete. Furthermore, the FTIR test showed that the shape of the wavelength spectrum diagram and the area of chemical bond peaks were the same among hemp, plastic, and other natural fibers.

Abstract: High demand for using parts of natural materials, e.g., cores, fibers or leaves, as alternative additives are being increased. The main reasons are that natural materials can be served as renewable and eco-friendly choices such a sustainable development. Nevertheless, some limitations of applying those natural products, such as biodegradation, UV degradation, or weak bonding, are raised and need to be modified before further handling. One of the modification techniques for bio-based materials is chemical treatment by using alkaline solution (alkalization). Treatment process allows the plant's fiber to have fewer impurities as well as to increase the bonding on its contacting surface area. This research focuses on (i) effects of NaOH solution concentration on the pre-treatment properties of hemp fibers and (ii) self-treatment behavior of hemp fiber in geopolymer composites. The results show that the concentration of NaOH solution directly affected the pre-treatment process of hemp fiber as higher concentration from 1, 3, 5, 8, 10 to 12 Molar provided more vanishing level of fiber impurities, indicated by Contact Angle (CA) measurement and Fourier Transform Infrared (FT-IR) Spectroscopy analysis. With the concept of alkaline treatment, the self-treatment process was therefore applied for hemp fiber incorporated in alkaline-activated geopolymer matrix. The results illustrate the self-treatment behavior of hemp fiber in geopolymer composites, which could improve the final performances of the hardened products without conventional pre-treatment process.

Abstract: Composite materials do offer freedom to design a material fitting best to the requirements of a given application. In case of fiber reinforced polymers especially the low weight in combination with other favorable properties, e.g. high mechanical performance, are the driving force for their application. Materials from renewable resources are of high interest if sustainability is aimed. In this paper, in a holistic approach a green composite is aimed to be used in a rotor blade for wind energy production. The challenging topic for this approach is to identify a possibility to gain a thermoset resin being really green, i.e. based on renewable resources and being not critical, e.g. toxic, at any stage of the whole processing chain. For this purpose several different approaches are studied and compared with other solutions based on green resin systems from other resources and conventional petrochemical based resin systems. A hemp seed oil based epoxy resin has been tested successfully. But to be completely free of petrochemicals, bio-based hardener and catalysts are still an open topic. For manufacturing of a rotor blade an infusion process has been used and it was found, a through thickness impregnation of the natural fiber yarn based textile structure results in entrapped air. Only in-plane saturation delivered completely impregnated structures.

Abstract: This paper presents the research on the structure, short-term compression and tension of hemp fibers composite. The density of hemp fibers composite varied from ~40 to ~96 kg/m³. The mechanical characteristics of such hemp fibers composite mostly depend on the materials structure and density. By the mechanical tests it was determined that compressive stress of the hemp fibers composite depends on the direction of the load to the specimens face (perpendicular, across and parallel to the direction of formation).

Abstract: In this work, polypropylene composites reinforced by woven hemp fiber were fabricated using compression molding. The effects of compression temperature, ranging from 160 °C to 200 oC, on the tensile properties of the resulted composites were studied. The tensile tests of neat woven hemp fiber heated under different temperatures (160-280 oC) were also performed. The scanning electron microscopy (SEM) was employed to observe the fiber surface. The results showed that the tensile properties of the reinforced composites decreased with the increase of compression temperature, but a rise up to 40.31 MPa at 190 oC occurred. The tensile properties of the woven fibers decreased as the temperature increased, even a marked reduction at 220 oC. The SEM presents the fiber surface indicating the degradation of pectin or lignin on the fiber surface.

Abstract: Tensile strength of some natural fibers such as hemp is higher than that of steel. To determine tensile properties of hemp fiber, a fiber or bundle is tensile tested with universal testing machine that is controlled by personal computer. This paper presents a small tensile testing equipment that is controlled by Raspberry Pi (RPi), a credit-card-sized single-board computer. General Purpose Input Output (GPIO) pins on RPi were used for controlling the machine crosshead and receiving the tensile load that apply to a hemp bundle. A stepper motor was used to drive the crosshead. Tensile load was measured by using a load measurement system included load-cell, instrument amplifier, and analog-to-digital converter. The applied load and extension were real-time displayed and continuously recorded throughout the test. Testing hemp-fiber bundles with the proposed equipment found that their tensile strength and Youngs modulus were 446.75±184.36 MPa and 18.23±8.26 GPa, respectively. These results were in good agreement with the properties founded in other publications. Test results also found that hemp-fiber bundle with smaller diameter showed higher tensile strength than that of larger one.

Abstract: In this paper, the antibacterial property of hemp fiber was studied before and after extracted with ethanol. Simultaneously, the chemical composition of ethanol extract from hemp fiber was analyzed and characterized by UR and FT-IR. Experiment results show that, the antibacterial property of hemp fiber decreased after extracted with ethanol. The Inhibitory rate to Candida albicans decreased from85.7% to 64.4%. The Inhibitory rate to Staphylococcus aureus, Escherichia coli and Candida albicans deceased as extraction time prolonging, and attained equilibrium after about 4 hours. Through experiments and date analysis by using FT-IR and UV, hemp fiber contains chalcone. It is initially argued that the active anti-bacterial constituents of hemp fiber may be alkaloids, flavones and saponins.