The impact of fibre processing on the mechanical properties of epoxy matrix composites and wood-based particleboard reinforced with hemp (Cannabis sativa L.) fibre

AbstractThis work investigated the impact that the processing of hemp (C. sativa L.) fibre has on the mechanical properties of unidirectional fibre-reinforced epoxy resin composites loaded in axial tension, and particleboard reinforced with aligned fibre bundles applied to one surface of the panel. For this purpose, mechanically processed (decorticated) and un-processed hemp fibre bundles, obtained from retted and un-retted hemp stems, were utilised. The results clearly show the impact of fibre reinforcement in both materials. Epoxy composites reinforced with processed hemp exhibited 3.3 times greater tensile strength when compared to the un-reinforced polymer, while for the particleboards, the bending strength obtained in those reinforced with processed hemp was 1.7 times greater than the un-reinforced particleboards. Moreover, whether the fibre bundles were processed or un-processed also affected the mechanical performance, especially in the epoxy composites. For example, the un-processed fibre-reinforced epoxy composites exhibited 49% greater work of fracture than the composites reinforced with processed hemp. In the wood-based particleboards, however, the difference was not significant. Additionally, observations of the fracture zone of the specimens showed different failure characteristics depending on whether the composites were reinforced with processed or un-processed hemp. Both epoxy composites and wood-based particleboards reinforced with un-processed hemp exhibited fibre reinforcement apparently able to retain structural integrity after the composite’s failure. On the other hand, when processed hemp was used as reinforcement, fibre bundles showed a clear cut across the specimen, with the fibre-reinforcement mainly failing at the composite's fracture zone.

Download Full-text

Effect of toughened polyamide-coated carbon fiber fabric on the mechanical performance and fracture toughness of CFRP

Journal of Composite Materials ◽

10.1177/0021998321999458 ◽

2021 ◽

pp. 002199832199945

Author(s):

Jong H Eun ◽

Bo K Choi ◽

Sun M Sung ◽

Min S Kim ◽

Joon S Lee

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Photoelectron Spectroscopy ◽

Mechanical Performance ◽

Epoxy Composites ◽

Scanning Calorimetry ◽

Internal Damage ◽

Impact Tests ◽

Flexural Tests ◽

The Impact

In this study, carbon/epoxy composites were manufactured by coating with a polyamide at different weight percentages (5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%) to improve their impact resistance and fracture toughness. The chemical reaction between the polyamide and epoxy resin were examined by fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray photoelectron spectroscopy. The mechanical properties and fracture toughness of the carbon/epoxy composites were analyzed. The mechanical properties of the carbon/epoxy composites, such as transverse flexural tests, longitudinal flexural tests, and impact tests, were investigated. After the impact tests, an ultrasonic C-scan was performed to reveal the internal damage area. The interlaminar fracture toughness of the carbon/epoxy composites was measured using a mode I test. The critical energy release rates were increased by 77% compared to the virgin carbon/epoxy composites. The surface morphology of the fractured surface was observed. The toughening mechanism of the carbon/epoxy composites was suggested based on the confirmed experimental data.

Download Full-text

Effect of Submicron Glass Fiber Modification on Mechanical Properties of Short Carbon Fiber Reinforced Polymer Composite with Different Fiber Length

Journal of Composites Science ◽

10.3390/jcs4010005 ◽

2020 ◽

Vol 4 (1) ◽

pp. 5

Author(s):

Nhan Thi Thanh Nguyen ◽

Obunai Kiyotaka ◽

Okubo Kazuya ◽

Fujii Toru ◽

Shibata Ou ◽

...

Keyword(s):

Mechanical Properties ◽

Carbon Fiber ◽

Glass Fiber ◽

Fiber Length ◽

Bending Strength ◽

Mechanical Performance ◽

Volume Fraction ◽

Fiber Concentration ◽

Static Tests ◽

The Impact

In this research, three kinds of carbon fiber (CF) with lengths of 1, 3, and 25 mm were prepared for processing composite. The effect of submicron glass fiber addition (sGF) on mechanical properties of composites with different CF lengths was investigated and compared throughout static tests (i.e., bending, tensile, and impact), as well as the tension-tension fatigue test. The strengths of composites increased with the increase of CF length. However, there was a significant improvement when the fiber length changed from 1 to 3 mm. The mechanical performance of 3 and 25 mm was almost the same when having an equal volume fraction, except for the impact resistance. Comparing the static strengths when varying the sGF content, an improvement of bending strength was confirmed when sGF was added into 1 mm composite due to toughened matrix. However, when longer fiber was used and fiber concentration was high, mechanical properties of composite were almost dependent on the CF. Therefore, the modification effect of matrix due to sGF addition disappeared. In contrast to the static strengths, the fatigue durability of composites increased proportionally to the content of glass fiber in the matrix, regardless to CF length.

Download Full-text

Mechanical Performance of Unstitched and Silk Fiber-Stitched Woven Kenaf Fiber-Reinforced Epoxy Composites

Materials ◽

10.3390/ma13214801 ◽

2020 ◽

Vol 13 (21) ◽

pp. 4801

Author(s):

Yasir Khaleel Kirmasha ◽

Mohaiman J. Sharba ◽

Zulkiflle Leman ◽

Mohamed Thariq Hameed Sultan

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Mechanical Performance ◽

Mechanical Test ◽

Natural Fibers ◽

Silk Fiber ◽

Epoxy Composites ◽

Test Results ◽

The Impact ◽

Woven Kenaf

Fiber composites are known to have poor through-thickness mechanical properties due to the absence of a Z-direction binder. This issue is more critical with the use of natural fibers due to their low strength compared to synthetic fibers. Stitching is a through-thickness toughening method that is used to introduce fibers in the Z-direction, which will result in better through-thickness mechanical properties. This research was carried out to determine the mechanical properties of unstitched and silk fiber-stitched woven kenaf-reinforced epoxy composites. The woven kenaf mat was stitched with silk fiber using a commercial sewing machine. The specimens were fabricated using a hand lay-up method. Three specimens were fabricated, one unstitched and two silk-stitched with deferent stitching orientations. The results show that the stitched specimens have comparable in-plane mechanical properties to the unstitched specimens. For the tensile mechanical test, stitched specimens show similar and 17.1% higher tensile strength compared to the unstitched specimens. The flexural mechanical test results show around a 9% decrease in the flexural strength for the stitched specimens. On the other hand, the Izod impact mechanical test results show a significant improvement of 33% for the stitched specimens, which means that stitching has successfully improved the out-of-plane mechanical properties. The outcome of this research indicates that the stitched specimens have better mechanical performance compared to the unstitched specimens and that the decrease in the flexural strength is insignificant in contrast with the remarkable enhancement in the impact strength.

Download Full-text

The Influence of Functionalized TiO2 with Poly(methyl methacrylate) on the Mechanical Properties of TiO2/Epoxy Nanocomposites

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.415-417.297 ◽

2011 ◽

Vol 415-417 ◽

pp. 297-301

Author(s):

Hong Bo Liang ◽

Lei Xiong ◽

Hai Tao Xu ◽

Jing Guan

Keyword(s):

Mechanical Properties ◽

Methyl Methacrylate ◽

Bending Strength ◽

Impact Testing ◽

Epoxy Composites ◽

Gravimetric Analysis ◽

Thermal Gravimetric ◽

1H Nuclear Magnetic Resonance ◽

Ft Ir ◽

The Impact

The functionalized TiO2 with poly(methyl methacrylate) (TiO2-PMMA) was prepared by atom transfer radical polymerization (ATRP), and its reinforcement for epoxy composites was studied. The functionalized TiO2 was characterized by Fourier transform infrared (FT-IR), Thermal gravimetric analysis (TGA) and 1H nuclear magnetic resonance (NMR). The properties of nanocomposites were measured by impact testing, bending experiment and Scanning electron microscopy (SEM). Because of the grafting of PMMA and the higher interaction between TiO2-PMMA and epoxy matrix, the composites exhibited the enhancement of mechanical properties at lower content. As the functionalized TiO2 content is 0.5 wt%, the impact strength and bending strength of composite increased nearly 142% and 37%, respectively, compared to the neat epoxy resin.

Download Full-text

Influence of Air Plasma Pretreatments on Mechanical Properties in Metal-Reinforced Laminated Wood

Frontiers in Materials ◽

10.3389/fmats.2021.796474 ◽

2022 ◽

Vol 8 ◽

Author(s):

Sebastian Dahle ◽

Kavyashree Srinivasa ◽

Jure Žigon ◽

Arnaud Maxime Cheumani Yona ◽

Georg Avramidis ◽

...

Keyword(s):

Mechanical Properties ◽

Bending Strength ◽

Mechanical Performance ◽

Mechanical Load ◽

Urea Formaldehyde ◽

Air Plasma ◽

Adhesive Systems ◽

Plasma Treatments ◽

Structural Applications ◽

The Impact

The use of wood-based materials in building and construction is constantly increasing as environmental aspects and sustainability gain importance. For structural applications, however, there are many examples where hybrid material systems are needed to fulfil the specific mechanical requirements of the individual application. In particular, metal reinforcements are a common solution to enhance the mechanical properties of a wooden structural element. Metal-reinforced wood components further help to reduce cross-sectional sizes of load-bearing structures, improve the attachment of masonry or other materials, enhance the seismic safety and tremor dissipation capacity, as well as the durability of the structural elements in highly humid environments and under high permanent mechanical load. A critical factor to achieve these benefits, however, is the mechanical joint between the different material classes, namely the wood and metal parts. Currently, this joint is formed using epoxy or polyurethane (PU) adhesives, the former yielding highest mechanical strengths, whereas the latter presents a compromise between mechanical and economical constraints. Regarding sustainability and economic viability, the utilization of different adhesive systems would be preferable, whereas mechanical stabilities yielded for metal-wood joints do not permit for the use of other common adhesive systems in such structural applications. This study extends previous research on the use of non-thermal air plasma pretreatments for the formation of wood-metal joints. The plasma treatments of Norway spruce [Picea abies (L.) Karst.] wood and anodized (E6/EV1) aluminum AlMgSi0.5 (6060) F22 were optimized, using water contact angle measurements to determine the effect and homogeneity of plasma treatments. The adhesive bond strengths of plasma-pretreated and untreated specimens were tested with commercial 2-component epoxy, PU, melamine-urea formaldehyde (MUF), polyvinyl acetate (PVAc), and construction adhesive glue systems. The influence of plasma treatments on the mechanical performance of the compounds was evaluated for one selected glue system via bending strength tests. The impact of the hybrid interface between metal and wood was isolated for the tests by using five-layer laminates from three wood lamellae enclosing two aluminum plates, thereby excluding the influence of congeneric wood-wood bonds. The effect of the plasma treatments is discussed based on the chemical and physical modifications of the substrates and the respective interaction mechanisms with the glue systems.

Download Full-text

The Impact of Corrosion on the Mechanical Behavior of Bolt

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.168-170.408 ◽

2010 ◽

Vol 168-170 ◽

pp. 408-411

Author(s):

Xiao Yong Li

Keyword(s):

Mechanical Properties ◽

Experimental Investigation ◽

Corrosion Test ◽

Laboratory Tests ◽

Structural Integrity ◽

Mechanical Performance ◽

Rock Bolt ◽

Before And After ◽

The Impact ◽

Strength And Ductility

Corrosion is a negative contributor on the structural integrity of rock bolt and leads to degradation of the mechanical properties of steel rock bolt. Exposure to chloride, seawater, salt and saltwater and deicing chemical environments influences rock bolt and weakens it. In order to evaluate the influence of corrosion and the size of the steel on the mechanical properties of rock bolt, an experimental investigation was conducted on rock bolt whose rebar is 8, 12, 16, and 18 mm diameter, and which were artificially corroded for 10, 20, 30, 45, 60, 90, and 120 days. By the simulation corrosion test of loaded and unloaded bolts in Na2SO4 solution, the relation curves of the mechanical performance with the corrosive conditions and the corrosion time are given. The mechanical performance is compared between these two types of bolts. At the same time, the influential trend of the load on the mechanical performance of the corroded bolt is analyzed. The laboratory tests suggest that corrosion duration and rebar size had a significant impact on the strength and ductility degradation of the specimens. after being corroded in Na2SO4 solution, both the ultimate bearing capacity and the maximal tensility of loaded bolt decrease far more than those of unloaded bolt, and the endurance and service life of loaded bolt will also be shortened much more severely. The tensile mechanical properties before and after corrosion indicated progressive variation and drastic drop in their values.

Download Full-text

Influence of layering pattern of modified kenaf fiber on thermomechanical properties of epoxy composites

Progress in Rubber Plastics and Recycling Technology ◽

10.1177/1477760619895010 ◽

2019 ◽

Vol 36 (1) ◽

pp. 47-62

Author(s):

AR Mohammed ◽

MS Nurul Atiqah ◽

Deepu A Gopakumar ◽

MR Fazita ◽

Samsul Rizal ◽

...

Keyword(s):

Mechanical Properties ◽

Chemical Modification ◽

Epoxy Matrix ◽

Epoxy Composites ◽

Woven Composites ◽

Fiber Reinforced ◽

Kenaf Fiber ◽

Kenaf Fibers ◽

The Impact ◽

Woven Kenaf

Natural fiber-reinforced composites gained considerable interest in the scientific community due to their eco-friendly nature, cost-effective, and excellent mechanical properties. Here, we reported a chemical modification of kenaf fiber using propionic anhydride to enhance the compatibility with the epoxy matrix. The incorporation of the modified woven and nonwoven kenaf fibers into the epoxy matrix resulted in the improvement of the thermal and mechanical properties of the composite. The thermal stability of the epoxy composites was enhanced from 403°C to 677°C by incorporating modified woven kenaf fibers into the epoxy matrix. The modified and unmodified woven kenaf fiber-reinforced epoxy composites had a tensile strength of 64.11 and 58.82 MPa, respectively. The modified woven composites had highest flexural strength, which was 89.4 MPa, whereas, for unmodified composites, it was 86.8 MPa. The modified woven fiber-reinforced epoxy composites showed the highest value of flexural modulus, which was 6.0 GPa compared to unmodified woven composites (5.51 GPa). The impact strength of the epoxy composites was enhanced to 9.43 kJ m−2 by the incarnation of modified woven kenaf fibers into epoxy matrix. This study will be an effective platform to design the chemical modification strategy on natural fibers for enhancing the compatibility toward the hydrophobic polymer matrices.

Download Full-text

Enhancing Mechanical Properties of Various Sintered Pellets with Nano-Additives

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.410.62 ◽

2021 ◽

Vol 410 ◽

pp. 62-67

Author(s):

Tien Hiep Nguyen ◽

Yury V. Konyukhov ◽

Van Minh Nguyen

Keyword(s):

Mechanical Properties ◽

Spark Plasma Sintering ◽

Bending Strength ◽

Size Range ◽

Pressureless Sintering ◽

Plasma Sintering ◽

Spark Plasma ◽

Nano Additives ◽

Free Spaces ◽

The Impact

The impact of Fe, Co, Ni nano-additives on the density, microhardness and bending strength was investigated for several sintered pellets. Fe, Co, Ni nanopowders (NP) were prepared in the size range 67-94 nm using chemical metallurgy techniques. These powders (0.5 wt. %) were dispersed into three sets of micron powders: Co (+0.5 wt. % Co NP); Fe (+0.5 wt. % Fe NP); Fe+0.5wt. % C (+0.5 wt. % Co and 0.5 wt. % Ni NP). Mixtures were further mixed and processed using a magnetic mill and a turbulent mixer. Sintering was carried out using spark plasma sintering (SPS) as well as pressureless sintering (PS). The densities of sintered pellets were found to increase by 2.5-3% (SPS) and 3-5% (PS) in the presence of nano-additives; corresponding increases in microhardness and bending strength were determined to be 7.9-11.1% and 17.9-38.7%, respectively. These results are discussed in terms enhanced packing due to interparticle sliding and the filling of free spaces with the nanodisperse phase.

Download Full-text

An attempt to use „Tetra Pak” waste material in particleboard technology

Annals of WULS, Forestry and Wood Technology ◽

10.5604/01.3001.0015.2376 ◽

2021 ◽

Vol 114 ◽

pp. 70-75

Author(s):

Radosław Auriga ◽

Piotr Borysiuk ◽

Alicja Auriga

Keyword(s):

Mechanical Properties ◽

Water Absorption ◽

Bending Strength ◽

Physical And Mechanical Properties ◽

Core Layer ◽

Waste Material ◽

Thickness Swelling ◽

The Core ◽

Tetra Pak ◽

The Impact

An attempt to use „Tetra Pak” waste material in particleboard technology. The study investigates the effect of addition Tetra Pak waste material in the core layer on physical and mechanical properties of chipboard. Three-layer chipboards with a thickness of 16 mm and a density of 650 kg / m3 were manufactured. The share of Tetra Pak waste material in the boards was varied: 0%, 5%, 10% and 25%. The density profile was measured to determine the impact of Tetra Pak share on the density distribution. In addition, the manufactured boards were tested for strength (MOR, MOE, IB), thickness swelling and water absorption after immersion in water for 2 and 24 hours. The tests revealed that Tetra Pak share does not affect significantly the value of static bending strength and modulus of elasticity of the chipboard, but it significantly decreases IB. Also, it has been found that Tetra Pak insignificantly decreases the value of swelling and water absorption of the chipboards.

Download Full-text

The Impact of Paraffin-Thermal Modification of Beech Wood on Its Biological, Physical and Mechanical Properties

Forests ◽

10.3390/f10121102 ◽

2019 ◽

Vol 10 (12) ◽

pp. 1102 ◽

Cited By ~ 3

Author(s):

Ladislav Reinprecht ◽

Miroslav Repák

Keyword(s):

Mechanical Properties ◽

Bending Strength ◽

Beech Wood ◽

Physical And Mechanical Properties ◽

Brown Rot ◽

European Beech ◽

White Rot ◽

White Rot Fungus ◽

Poria Placenta ◽

The Impact

The European beech (Fagus sylvatica L.) wood was thermally modified in the presence of paraffin at the temperatures of 190 or 210 °C for 1, 2, 3 or 4 h. A significant increase in its resistance to the brown-rot fungus Poria placenta (by 71.4%–98.4%) and the white-rot fungus Trametes versicolor (by 50.1%–99.5%) was observed as a result of all modification modes. However, an increase in the resistance of beech wood surfaces to the mold Aspergillus niger was achieved only under more severe modification regimes taking 4 h at 190 or 210 °C. Water resistance of paraffin-thermally modified beech wood improved—soaking reduced by 30.2%–35.8% and volume swelling by 26.8%–62.9% after 336 h of exposure in water. On the contrary, its mechanical properties worsened—impact bending strength decreased by 17.8%–48.3% and Brinell hardness by 2.4%–63.9%.

Download Full-text