Hemp Fibre Reinforced Research Articles

Environmental assessment of woven hemp fibre reinforced epoxy composites and potential applications in aerospace and electric scooter industries

This paper aims to present a hemp-based natural fibres composite value chain that could be implemented in biocomposite structures and replace synthetic fibres. Life cycle assessment (LCA) allows the assessment of the environmental footprint of the hemp fibre reinforcement value chain. This general case is complemented with two hemp fibre reinforcement applications, i.e. (1) a hemp fibre reinforced epoxy-based aircraft dashboard panel and (2) a hemp fibre reinforced epoxy-based biomonocoque for an electric scooter. LCA is also used to assess the environmental footprint of the application cases. All the hemp fibre-based value chain applications shown here demonstrate a lower environmental footprint than the fossil-based reinforcement value chain, particularly regarding the global warming potential, among other impact categories except for the case where the specific tensile strength was used as the functional unit for comparison. Impact categories related to agricultural activities, such as the eutrophication potential, land use, and freshwater consumption, are higher for the hemp-based value chains than for conventional synthetic fibre-based solutions. This study shows how conventional synthetic fibre products have the potential to be replaced by hemp-based natural fibre solutions depending on the required applications, which could lower the environmental footprint and help contribute to the ongoing climate mitigation efforts.

Investigation of flexural properties of epoxy composite by utilizing graphene nanofillers and natural hemp fibre reinforcement

This study aims to determine the optimum reinforcement required to attain the best combination of flexural strength of modified green composites (graphene oxide + hemp fibre reinforced epoxy composites) for potential use in structural applications. An attempt was also made for the combination of graphene and hemp fibres to enhance load-bearing ability. The infusion of hemp and graphene was made by the weight of the base matrix (epoxy composite). Results showed that graphene reinforcement at 0.4 wt.% of matrix showed load-sustaining capacity of 0.76 kN or 760 MPa. In the case of hemp fibre reinforcement at 0.2 wt.% of the matrix, infusion showed enhanced load-bearing ability (0.79 kN or 790 MPa). However, the combination of graphene (0.1 wt.% graphene nanofillers) and hemp (5 wt.% hemp fibre) indicated a load-sustaining ability of 0.425 kN or 425 MPa, whereas maximum deflection was observed for specimen with hemp 7.5 % + graphene 0.2 % with 1.9 mm. Graphene addition to the modified composites in combination with natural fibres showed promising results in enhancing the mechanical properties under study. Moreover, graphene-modified composites exhibited higher thermal resistance compared to natural fibre reinforced composites. However, when nanofiller reinforcement exceeded a threshold value, the composites exhibited reduced flexural strength as a result of nanofiller agglomeration.

Mechanical and Physical Properties of Pineapple Leaf and Sun Hemp Fibre Reinforced Hybrid Natural Composite Fabricated by Compression Moulding Method

Mechanical and Physical Properties of Pineapple Leaf and Sun Hemp Fibre Reinforced Hybrid Natural Composite Fabricated by Compression Moulding Method

Nonwoven Hemp Fibre Reinforced Acrodur Biocomposites and their Mechanical Performance in Immersed Water

Nonwoven Hemp Fibre Reinforced Acrodur Biocomposites and their Mechanical Performance in Immersed Water

Impact Properties of the Chemically Treated Hemp Fibre Reinforced Polyester Composites

Plant based hemp fibre properties were found to be highly influenced by changes in the amounts of cellulose, hemicellulose and lignin constituents within the fibre. These fibre constituents play a major role for effective interfacial adhesion between the fibre and the matrix. Chemical treatments such as alkali (NaOH), acetyl (acetic acid & acetic anhydride) and silane (siloxane) treatments have the potential to react with constituent contents by varying their amounts. In this study, hemp fibre was treated with alkali (0–10 % NaOH), acetyl and silane chemicals. Treated fibres were mixed with polyester matrix to produce composites. The effects of chemical treatments on hemp fibres and the resulted polyester matrix composite were analysed through impact testing of the composite samples. Alkali treatments on hemp fibres enhanced the impact resistance properties (around 43 % lower absorbed energy and 40 % higher rebounded energy) of its composites compared to the untreated cases. Lower absorption energy and higher rebounded energy indicates strong interfacial bonding between the fibre and matrix. Improvements are governed by the removal of hemicellulose and lignin from the fibre, which provides a platform for better chemical reactions between fibres and matrix. On the other hand, acetyl treatments on the higher concentrations of NaOH pre-treated fibres reduced the fibres’ ability to support impact loadings (22 % higher rebounded energy compared to the untreated cases). In the two treatment conditions, fibre lessen their strength due to excessive removal of hemicellulose and lignin constituents, and composites exhibited lower impact properties compared to the NaOH treated samples. Similar impact properties were also recorded for alkali pre-treated silanised composites. As alkali pre-treatment removed the hydroxyl groups from the fibre, further silane treatment could not develop silanols to create strong interface bonding. As a result, composites failed under lower impact resistance compared to the NaOH treated samples.

Influence of Eggshell Nanoparticles and Effect of Alkalization on Characterization of Industrial Hemp Fibre Reinforced Epoxy Composites

Nowadays most of the researchers are focusing their research on pollution free environment, bio-degradable nature and balanced ecological aspect while fabricating the composite materials rather than mechanical strengths, costs, processing methodologies, etc. The objective of this experimental study is to analyze the influence of the bio-based eggshell nanoparticles on the thermal and morphological properties of alkali-treated hemp fibre reinforced epoxy composites. The composites were fabricated by hand lay-up process followed by compression molding technique and the properties of composites are analyzed by using thermo-gravimetric analysis, Fourier transform Infra-red spectroscopy, differential scanning calorimetry and X-ray diffraction techniques. The mechanical properties such as tensile, shear, flexural and impact strengths as well as water absorption characteristics of these composites are also investigated. The morphological characteristics were analyzed by scanning electron microscopy analysis. The results clearly showed that the incorporation of eggshell nanoparticles has significant influence on the thermal and morphological properties of alkali-treated hemp fibre composites.

Hygroscopic and Mechanical Properties of Hemp Fibre Reinforced Biocomposites

Hygroscopic and Mechanical Properties of Hemp Fibre Reinforced Biocomposites

Morphological structure and thermomechanical properties of hemp fibre reinforced poly(lactic acid) Nanocomposites plasticized with tributyl citrate

PLA was physically modified by filling with an inorganic additive, natural fibre with additional of tributyl citrate (TBC) plasticizer. PLA composites were prepared with a film stacking method and analysed by SEM and thermomechanometry to investigate the physical and mechanical properties of the hybrid composites. TBC improved the interfacial interaction of hemp fibres with the PLA Nanosilica matrix as revealed by SEM morphology. The thermomechanical properties of PLA composites showed that the reinforcement of hemp fibre and Nanosilica enhanced the mechanical properties of the composites. Efficient dispersion of Nanosilica resulted in strong interfacial interaction between PLA matrix and Nanosilica, improved the mechanical performance of the PLA matrix.

Impact Properties of Hemp Fibre Reinforced Cementitious Composites

The construction industry has seen an incredibly fast increase in utilizing natural fibres for making low-cost building materials to achieve sustainable construction. One of such applications is natural fibre-reinforced cementitious materials for either structural or non-structural purpose. Impact properties are engineering properties received increasing attentions from engineering community for structural materials. This research therefore studies impact resistance of hemp fibre reinforced cementitious composites at early ages. Hemp fibre with various lengths, 10 mm and 20 mm, are utilized to reinforce cementitious materials. Hemp fibre reinforced cementitious composite slabs were tested under repeating dropping mass till failure at the age of 7, 14 and 28 days. Cracking behaviour, impact resistance, absorbed impact energy and survived impact blows upon failure are qualitatively/quantitatively analysed. It has been found that 20 mm-long hemp fibre reinforcement leads to higher impact resistance, more absorbed impact energy and survived more impact blows upon failure. Cementitious composite slabs reinforced by 20 mm-long hemp fibres exhibit higher impact crack resistance ratio than those reinforced by 10 mm-long fibres. Longer fibres are more effective in inhibiting the growth of micro-cracks and blunting the propagation of micro-cracks before they join up to form macro cracks leading to ultimate failure.

Preparation, Properties, Protein Cross-Linking and Biodegradability of Plasticizer-Solvent Free Hemp Fibre Reinforced Wheat Gluten, Glutenin, and Gliadin Composites

The present study is aimed at evaluating the use of plant-based polymers and fibres for the production of sustainable biocomposites. For the first time, plasticiser/solvent-free hemp fibre-reinforc ...

Evaluation of Water Absorption Damage in Hemp Fibre Reinforced Unsaturated Polyester Composites by the Nanoindentation Testing

The effect of water absorption damage on the nanohardness and elastic modulus properties of the hemp fibre reinforced unsaturated polyester composites (HFRUPC) have been investigated using the nanoindentation testing. HFRUPC specimens containing 0, 28, 37 and 45 fibre wt.%, corresponding to neat UP, UP/3 layer hemp, UP/4 layer hemp and UP/5 layer hemp, respectively, were prepared and subjected to water immersion tests in a de-ionised water bath at 25 C and 100 C for different time durations. Elastic modulus and nanohardness properties of water immersed specimens subjected to both aging conditions are evaluated and compared alongside dry composite specimens. The elastic modulus and nanohardness properties of HFRUPC specimens were found to increase with the increase in fibre wt.% and decrease with increase in percentage moisture uptake. Nanoindentation is an effective technique to measure elastic modulus and hardness on a nanometer range. Its attractiveness lies largely from the fact that nanomechanical properties can be determined directly from indentation load and displacement measurements. SEM study was also applied to relate the decrease in properties as a result of water uptake in hemp composites.

Influence of Hygrothermal Ageing on the Physico-Mechanical Properties of Alkali Treated Industrial Hemp Fibre Reinforced Polylactic Acid Composites

30 wt% aligned untreated long hemp fibre/polylactic acid (AUL) and aligned alkali treated long hemp fibre/polylactic acid (AAL) composites were produced by film stacking and subjected to hygrothermal ageing environment along with neat polylactic acid (PLA). Hygrothermal ageing was carried out by immersing samples in distilled water at 25 and 50 °C over a period of 3 months. It was found that both neat PLA and composites followed Fickian diffusion. Higher temperature generally increased the Diffusion coefficient, D of neat PLA and composites, as well as shortening the saturation time. Neat PLA had the lowest D value followed by AAL composites and then AUL composites. After hygrothermal ageing, tensile and flexural strength, Young’s and flexural modulus and KIc were found to decrease and impact strength was found to increase for both AUL and AAL composites. AUL composites had greater overall reduction in mechanical properties than that for AAL composites after hygrothermal ageing. Crystallinity contents of the hygrothermal aged composites support the results of the deterioration of mechanical properties upon exposure to hygrothermal ageing environment.

Creep Behaviour of Natural Fibre Reinforced Unsaturated Polyester Composites

Hemp fibre reinforced unsaturated polyester composites (HFRUPE) containing different fibre volume percentages (10, 15, 21 and 26%) were prepared and subjected to short term flexural creep tests to investigate creep behaviour. The tests were conducted at ambient and elevated temperatures and at low to medium stress levels. Strain versus time curves (of both hemp and glass fibre reinforced specimens) were plotted directly from the experimental results. These show that the process of flexural creep behaviour is greatly influenced by both stress level and temperature. Comparison with results obtained for glass fibre reinforced specimens reveal that the use of hemp fibre reinforcement results in improved creep resistance at ambient temperature. At low temperature, 3 layered hemp reinforced composite specimen showed similar creep resistance properties to CSM samples. From the characteristics of the resultant creep curves, it is obvious that creep strain of composite samples is significant at elevated temperatures. Creep performance deteriorates as temperatures increase above glass transition temperatures for unreinforced UPE specimens.

Influence of Separation and Processing Systems on Morphology and Mechanical Properties of Hemp and Wood Fibre Reinforced Polypropylene Composites

ABSTRACT The separation processes of natural fibres and the technique of composite processing influence the fibre degradation, length and herewith the composites properties in a wide range. Different separation processes (mechanical, refiner and enzymatic separation) were investigated with hemp and partially with flax and wheat straw. Selected fibres were mixed with PP in a cascade mixer (heat-cooling mixer system) or compounded in a twin screw extruder and formed into test specimens by injection moulding with 40 wt.% fibre content. Thermomechanical processed hemp fibre-PP composites showed higher mechanical properties in cascade mixer process compared to twin-screw extruder or agglomerated process. Wood fibre reinforced polypropylene composites containing hard wood fibre were prepared by extrusion-injection moulding, mixer-injection moulding, compression moulding and direct extrusion (profile) process with 30 wt.% and 50 wt.% fibre contents. It is seen that extrusion-injection moulding process showed best properties compared to other processes in maximum cases.

Evaluation of the Mechanical Properties of Injection Moulded Hemp Fibre Reinforced Polypropylene Composites

In recent years, industrial hemp fibre reinforced thermoplastic composites have attracted substantial interest as potential structural materials. These composites have been subject to intense study for use in lightweight, recyclable and low cost applications. The aim of this research was to improve and evaluate the composite tensile strength and fibre/matrix interfacial adhesion by means of fibre treatment and addition of a coupling agent. Hemp fibre was digested in a small pressure vessel with a solution of 5wt% NaOH / 2wt% Na2SO3. Single fibre tensile tests were performed on treated and untreated fibres, and it was found that the alkali treatment resulted in an increase in fibre strength and an improvement in fibre separation. Composites containing either treated or untreated fibre, polypropylene and a maleic anhydride modified polypropylene (MAPP) coupling agent were then compounded in a twin-screw extruder and injection moulded into tensile test specimens. Tensile tests revealed that significant improvements in composite strength were made by using treated fibre and MAPP. The effect of MAPP on the interface of treated hemp fibre/polypropylene composites was assessed by means of the single fibre fragmentation test, and the interfacial shear strength was determined thereafter.

Influence of Alkali Treatment on the Interfacial Bond Strength of Industrial Hemp Fibre Reinforced Epoxy Composites: Effect of Variation from the Ideal Stoicheometric Ratio of Epoxy Resin to Curing Agent

Industrial hemp fibre was treated with alkali and the influence of this treatment on interfacial shear strength (assessed using the single fibre pull-out test) and composite strength with an epoxy resin, over a range of epoxy resin to curing agent ratios, was investigated. Scanning electron microscopy was conducted to assess the fracture behaviour of the composite tensile test specimens. It was found that alkali treatment increased the interfacial shear strength and composite tensile strength, Young’s modulus and elongation at break. The highest tensile strength was obtained with an epoxy resin to curing agent ratio of 1:1 while the best Young’s modulus was achieved with a resin to curing agent ratio of 1:1.2.

Fungal and Alkali Interfacial Modification of Hemp Fibre Reinforced Composites

The aim of the current work was to investigate using fungi to treat hemp fibre to create better bonding characteristics in natural fibre reinforced polypropylene composites. X-ray diffraction (XRD), lignin testing and scanning electron microscopy (SEM), were used to characterise the effect of treatment on hemp fibres. A combined alkali and fungal treated fibre composite produced the highest tensile strength of 48.3 MPa, an increase of 32% compared to composites with untreated fibre.

The low velocity impact response of non-woven hemp fibre reinforced unsaturated polyester composites

Hemp fibre reinforced unsaturated polyester composites (HFRUPE) were subjected to low velocity impact tests in order to study the effects of non-woven hemp fibre reinforcement on their impact properties. HFRUPE composites specimens containing 0, 0.06, 0.10, 0.15, 0.21 and 0.26 fibre volume fractions (Vf) were prepared and their impact response compared with samples containing an equivalent fibre volume fraction of chopped strand mat E-glass fibre reinforcement. Post-impact damage was assessed using scanning electron microscopy (SEM). A significant improvement in load bearing capability and impact energy absorption was found following the introduction hemp fibre as reinforcement. The results indicate a clear correlation between fibre volume fractions, stiffness of the composite laminate, impact load and total absorbed energy. Unreinforced unsaturated polyester control specimens exhibited brittle fracture behaviour with a lower peak load, lower impact energy and less time to fail than hemp reinforced unsaturated polyester composites. The impact test results show that the total energy absorbed by 0.21 fibre volume fraction (four layers) of hemp reinforced specimens is comparable to the energy absorbed by the equivalent fibre volume fraction of chopped strand mat E-glass fibre reinforced unsaturated polyester composite specimens.

Evaluation of the Influence of Fibre Length and Concentration on Mechanical Performance of Hemp Fibre Reinforced Polypropylene Composite

The paper deals widi die evaluation of interfacial shear stress (ISS) between reinforcement fibre (hemp) and polypropylene matrix through single fibre pull-out method and subsequently the critical length of the composite grade hemp fibre has been determined. In the present study the average ISS value of 5.9 MPa was used to determine the critical length of hemp fibre, which was found to be 3.4 mm. The theoretical prediction of the tensilestrength and modulus of hemp-polypropylene composite by using Kelly-Tyson and Cox-Krenchel models, respectively, have been reported in the paper. Model results were validated by experimental works with different fibre lengths and volume fraction of hemp fibre in the composite. The effect of fibre length and content on the flexural strength and stiffness of the hemp-polypropylene composite has also been studied. The effect of moisture absorption on composite tensile strength was predicted by modifying the Kelly-Tyson model. The model curve was also compared with another set of experimental works done at differentmoisture contents in the composite.