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Flax (Linum usitatissimum L.) fibres are commonly used as reinforcement of composite materials. Nevertheless, literature shows that the compressive strength of flax-based composites is rather modest compared with materials reinforced by synthetic fibres. The present article investigates the compressive strength of flax fibre bundles both within the stems and in unidirectional (UD) composites. In this way, an optimised arrangement of fibre bundles inside the plant is assumed. Damage mechanisms are found to be similar in the stem and within flax-based UD materials, namely by buckling of fibre bundles, a typical failure mechanism of UD composites. Inside the stems, this phenomenon is highlighted by nanotomography, which underlines the key role of the woody core in the buckling resistance of the plant. For UD, failure can also be studied by scanning electron microscopy (SEM). The same ranges of average compressive strength values are estimated for flax fibre bundles, being 206 MPa within the stem and 242 MPa within UD composites. Finally, this study highlights that, if a flax stem is an optimised natural structure, the compressive strength of flax fibre bundles seems to be a limiting factor for structural applications of flax-based composite materials.
Christophe Baley; Camille Goudenhooft; Patrick Perré; Pin Lu; Floran Pierre; Alain Bourmaud. Compressive strength of flax fibre bundles within the stem and comparison with unidirectional flax/epoxy composites. Industrial Crops and Products 2018, 130, 25 -33.
AMA StyleChristophe Baley, Camille Goudenhooft, Patrick Perré, Pin Lu, Floran Pierre, Alain Bourmaud. Compressive strength of flax fibre bundles within the stem and comparison with unidirectional flax/epoxy composites. Industrial Crops and Products. 2018; 130 ():25-33.
Chicago/Turabian StyleChristophe Baley; Camille Goudenhooft; Patrick Perré; Pin Lu; Floran Pierre; Alain Bourmaud. 2018. "Compressive strength of flax fibre bundles within the stem and comparison with unidirectional flax/epoxy composites." Industrial Crops and Products 130, no. : 25-33.
Flax (Linum usitatissimum L.) is a plant of industrial interest. Its fibres have traditionally been used for textile applications and more recently, for composite reinforcement. To increase fibre yields, varietal selection has been used to develop varieties having high fibre content while retaining good resistance to lodging. This selection process has led to impressively slender structures of flax compared to other herbaceous plants. The present study focuses on the mechanical stability of flax related to its specific architecture. An anatomical study of transverse sections provides information about the architecture of flax stems, including the repartition of the internal reinforcing tissues being phloem fibres and xylem. Then, by using three-point bending tests, flexural modulus is evaluated along the stem. The safety factor (SF) against buckling for the plant was estimated based on Greenhill's model, taking into account gradients in diameter, load, and elastic modulus. Although flax plants have an unusually slender structure, they are mechanically stable. The stability of the plant is ensured by a high stem flexural modulus. This originates from an external ring composed of high-performance fibres, while an inner thick porous xylem provides the plant with a high resistance to local buckling. This is useful information for breeders, demonstrating that it is possible to keep increasing fibre yield without jeopardising plant stability.
Camille Goudenhooft; Tancrède Alméras; Alain Bourmaud; Christophe Baley. The remarkable slenderness of flax plant and pertinent factors affecting its mechanical stability. Biosystems Engineering 2018, 178, 1 -8.
AMA StyleCamille Goudenhooft, Tancrède Alméras, Alain Bourmaud, Christophe Baley. The remarkable slenderness of flax plant and pertinent factors affecting its mechanical stability. Biosystems Engineering. 2018; 178 ():1-8.
Chicago/Turabian StyleCamille Goudenhooft; Tancrède Alméras; Alain Bourmaud; Christophe Baley. 2018. "The remarkable slenderness of flax plant and pertinent factors affecting its mechanical stability." Biosystems Engineering 178, no. : 1-8.
Flax fibers (Linum Usitatissimum L.) are currently used for textile applications and composite reinforcement. Due to its industrial importance, flax is the subject of a varietal selection work in view of obtaining varieties with higher fiber yields, but also exhibiting a greater lodging resistance. Indeed, lodging sometimes happens within flax fields, complicating plant harvest and compromising yields. Interestingly, it sometimes occurs that flax stems restore from lodging through a gravitropic reaction. Depending on the time of lodging, variations in elementary fiber mechanical performances, monitored by tensile tests appeared to be more or less pronounced, being greater in the earliest stage of the experiment, and also depend on the studied side of the stem curvature. Namely, the pulling of the stems provides fibers with the most emphasized changes, in terms of strength at break, filling rate (presence of a fiber lumen) as well as cell wall tangent modulus. Finally, differences between tilted and control fibers diminish as the plant maturity progresses, with only slight remaining dissimilarities at plant maturity. Thus, flax fibers are involved in the plant gravitropic reaction and maintain their efficient mechanical characteristic despite lodging, through the adjustability of their cell wall performances over fiber thickening, which is a major result for fiber suppliers and composite manufacturers.
Camille Goudenhooft; Alain Bourmaud; Christophe Baley. Study of plant gravitropic response: Exploring the influence of lodging and recovery on the mechanical performances of flax fibers. Industrial Crops and Products 2018, 128, 235 -238.
AMA StyleCamille Goudenhooft, Alain Bourmaud, Christophe Baley. Study of plant gravitropic response: Exploring the influence of lodging and recovery on the mechanical performances of flax fibers. Industrial Crops and Products. 2018; 128 ():235-238.
Chicago/Turabian StyleCamille Goudenhooft; Alain Bourmaud; Christophe Baley. 2018. "Study of plant gravitropic response: Exploring the influence of lodging and recovery on the mechanical performances of flax fibers." Industrial Crops and Products 128, no. : 235-238.
Camille Goudenhooft; Alain Bourmaud; Christophe Baley. Conventional or greenhouse cultivation of flax: What influence on the number and quality of flax fibers? Industrial Crops and Products 2018, 123, 111 -117.
AMA StyleCamille Goudenhooft, Alain Bourmaud, Christophe Baley. Conventional or greenhouse cultivation of flax: What influence on the number and quality of flax fibers? Industrial Crops and Products. 2018; 123 ():111-117.
Chicago/Turabian StyleCamille Goudenhooft; Alain Bourmaud; Christophe Baley. 2018. "Conventional or greenhouse cultivation of flax: What influence on the number and quality of flax fibers?" Industrial Crops and Products 123, no. : 111-117.
Flax retting is a major bioprocess in the cultivation and extraction cycle of flax fibres. The aim of the present study is to improve the understanding of the evolution of fibre properties and ultrastructure caused by this process at the plant cell wall scale. Initially, investigations of the mechanical performances of the flax cell walls by Atomic Force Microscopy (AFM) in Peak Force mode revealed a significant increase (+33%) in the cell wall indentation modulus with retting time. Two complementary structural studies are presented here, namely using X-Ray Diffraction (XRD) and solid state Nuclear Magnetic Resonance (NMR). An estimation of the cellulose crystallinity index by XRD measurements, confirmed by NMR, shows an increase of 8% in crystallinity with retting mainly due to the disappearance of amorphous polymer. In addition, NMR investigations show a compaction of inaccessible cell wall polymers, combined with an increase in the relaxation times of the C4 carbon. This densification provides a structural explanation for the observed improvement in mechanical performance of the secondary wall of flax fibres during the field retting process.
Alain Bourmaud; David Siniscalco; Loïc Foucat; Camille Goudenhooft; Xavier Falourd; Bruno Pontoire; Olivier Arnould; Johnny Beaugrand; Christophe Baley. Evolution of flax cell wall ultrastructure and mechanical properties during the retting step. Carbohydrate Polymers 2018, 206, 48 -56.
AMA StyleAlain Bourmaud, David Siniscalco, Loïc Foucat, Camille Goudenhooft, Xavier Falourd, Bruno Pontoire, Olivier Arnould, Johnny Beaugrand, Christophe Baley. Evolution of flax cell wall ultrastructure and mechanical properties during the retting step. Carbohydrate Polymers. 2018; 206 ():48-56.
Chicago/Turabian StyleAlain Bourmaud; David Siniscalco; Loïc Foucat; Camille Goudenhooft; Xavier Falourd; Bruno Pontoire; Olivier Arnould; Johnny Beaugrand; Christophe Baley. 2018. "Evolution of flax cell wall ultrastructure and mechanical properties during the retting step." Carbohydrate Polymers 206, no. : 48-56.
Nanofibrous membranes based on polycaprolactone (PCL) have a large potential for use in biomedical applications but are limited by the hydrophobicity of PCL. Blend electrospinning of PCL with other biomedical suited materials, such as gelatin (Gt) allows for the design of better and new materials. This study investigates the possibility of blend electrospinning PCL/Gt nanofibrous membranes which can be used to design a range of novel materials better suited for biomedical applications. The electrospinnability and stability of PCL/Gt blend nanofibers from a non-toxic acid solvent system are investigated. The solvent system developed in this work allows good electrospinnable emulsions for the whole PCL/Gt composition range. Uniform bead-free nanofibers can easily be produced, and the resulting fiber diameter can be tuned by altering the total polymer concentration. Addition of small amounts of water stabilizes the electrospinning emulsions, allowing the electrospinning of large and homogeneous nanofibrous structures over a prolonged period. The resulting blend nanofibrous membranes are analyzed for their composition, morphology, and homogeneity. Cold-gelling experiments on these novel membranes show the possibility of obtaining water-stable PCL/Gt nanofibrous membranes, as well as nanostructured hydrogels reinforced with nanofibers. Both material classes provide a high potential for designing new material applications.
Lode Daelemans; Iline Steyaert; Ella Schoolaert; Camille Goudenhooft; Hubert Rahier; Karen De Clerck. Nanostructured Hydrogels by Blend Electrospinning of Polycaprolactone/Gelatin Nanofibers. Nanomaterials 2018, 8, 551 .
AMA StyleLode Daelemans, Iline Steyaert, Ella Schoolaert, Camille Goudenhooft, Hubert Rahier, Karen De Clerck. Nanostructured Hydrogels by Blend Electrospinning of Polycaprolactone/Gelatin Nanofibers. Nanomaterials. 2018; 8 (7):551.
Chicago/Turabian StyleLode Daelemans; Iline Steyaert; Ella Schoolaert; Camille Goudenhooft; Hubert Rahier; Karen De Clerck. 2018. "Nanostructured Hydrogels by Blend Electrospinning of Polycaprolactone/Gelatin Nanofibers." Nanomaterials 8, no. 7: 551.
Samuel Réquilé; Camille Goudenhooft; Alain Bourmaud; Antoine Le Duigou; Christophe Baley. Exploring the link between flexural behaviour of hemp and flax stems and fibre stiffness. Industrial Crops and Products 2018, 113, 179 -186.
AMA StyleSamuel Réquilé, Camille Goudenhooft, Alain Bourmaud, Antoine Le Duigou, Christophe Baley. Exploring the link between flexural behaviour of hemp and flax stems and fibre stiffness. Industrial Crops and Products. 2018; 113 ():179-186.
Chicago/Turabian StyleSamuel Réquilé; Camille Goudenhooft; Alain Bourmaud; Antoine Le Duigou; Christophe Baley. 2018. "Exploring the link between flexural behaviour of hemp and flax stems and fibre stiffness." Industrial Crops and Products 113, no. : 179-186.
The development of flax (Linum usitatissimum L.) fibers was studied to obtain better insight on the progression of their high mechanical performances during plant growth. Fibers at two steps of plant development were studied, namely the end of the fast growth period and at plant maturity, each time at three plant heights. The indentation modulus of the fiber cell wall was characterized by atomic force microscopy (AFM) using peak-force quantitative nano-mechanical property mapping (PF-QNM). Changes in the cell wall modulus with the cell wall thickening were highlighted. For growing plants, fibers from top and middle heights show a loose inner Gn layer with a lower indentation modulus than mature fibers, which exhibit thickened homogeneous cell walls made only of a G layer. The influence of these changes in the fiber cell wall on the mechanical performances of extracted elementary fibers was also emphasized by tensile tests. In addition, Raman spectra were recorded on samples from both growing and mature plants. The results suggest that, for the fiber cell wall, the cellulose contribution increases with fiber maturity, leading to a greater cell wall modulus of flax fibers.
Camille Goudenhooft; David Siniscalco; Olivier Arnould; Alain Bourmaud; Olivier Sire; Tatyana Gorshkova; Christophe Baley. Investigation of the Mechanical Properties of Flax Cell Walls during Plant Development: The Relation between Performance and Cell Wall Structure. Fibers 2018, 6, 6 .
AMA StyleCamille Goudenhooft, David Siniscalco, Olivier Arnould, Alain Bourmaud, Olivier Sire, Tatyana Gorshkova, Christophe Baley. Investigation of the Mechanical Properties of Flax Cell Walls during Plant Development: The Relation between Performance and Cell Wall Structure. Fibers. 2018; 6 (1):6.
Chicago/Turabian StyleCamille Goudenhooft; David Siniscalco; Olivier Arnould; Alain Bourmaud; Olivier Sire; Tatyana Gorshkova; Christophe Baley. 2018. "Investigation of the Mechanical Properties of Flax Cell Walls during Plant Development: The Relation between Performance and Cell Wall Structure." Fibers 6, no. 1: 6.
The present paper proposes to carefully study and describe the reinforcement mechanisms within a flax stem, which is an exceptional natural model of composite structure. Thanks to accurate microscopic investigations, with both optical and SEM method, we finely depicted the flax stem architecture, which can be view as a composite structure with an outer protection, a unidirectional ply on the periphery and a porous core; each component has a specific function, such as mechanical reinforcement for the unidirectional ply and the porous core. The significant mechanical role of fibres was underlined, as well as their local organisation in cohesive bundles, obtained because of an intrusive growth and evidenced in this work through nanomechanical AFM measurement and 3D reconstruction. Following a biomimetic approach, these data provide a source of inspiration for the composite materials of tomorrow.
Christophe Baley; Camille Goudenhooft; Marianne Gibaud; Alain Bourmaud. Flax stems: from a specific architecture to an instructive model for bioinspired composite structures. Bioinspiration & Biomimetics 2018, 13, 026007 .
AMA StyleChristophe Baley, Camille Goudenhooft, Marianne Gibaud, Alain Bourmaud. Flax stems: from a specific architecture to an instructive model for bioinspired composite structures. Bioinspiration & Biomimetics. 2018; 13 (2):026007.
Chicago/Turabian StyleChristophe Baley; Camille Goudenhooft; Marianne Gibaud; Alain Bourmaud. 2018. "Flax stems: from a specific architecture to an instructive model for bioinspired composite structures." Bioinspiration & Biomimetics 13, no. 2: 026007.
International audienceThe varietal selection of flax (Linum Usitatissimum L) has always focused on specific criteria fulfilling requirements of farmers and textile workers. Thus, the current development of composites using flax as reinforcement presents new challenges for flax breeders in terms of fiber quantities and quality. However, the impact of the varietal selection on the mechanical properties of resulting fibers is yet to be determined. In the present study, several architectural characteristics of flax stems are defined. Stem transverse sections from four varieties selected from the 1940s to 2011 are compared. Anatomical changes over time are highlighted. The most important ones involve the gap between fiber bundles and the amount of fibers which can be improved with the selection (from 7.8% to 13.4% of the tissue area per section). This trend coincides with the increase in biomass production over time expected from the selection work. Moreover, this study demonstrates that flax fibers preserve their good mechanical performances in spite of the anatomical differences. Thus, through varietal selection, it is possible to increase the biomass yield while preserving the excellent specific mechanical properties of flax fibers. Finally, flax fibers can compete with glass fibers to reinforce composite materials. (C) 2016 Elsevier B.V. All rights reserved
Camille Goudenhooft; Alain Bourmaud; Christophe Baley. Varietal selection of flax over time: Evolution of plant architecture related to influence on the mechanical properties of fibers. Industrial Crops and Products 2017, 97, 56 -64.
AMA StyleCamille Goudenhooft, Alain Bourmaud, Christophe Baley. Varietal selection of flax over time: Evolution of plant architecture related to influence on the mechanical properties of fibers. Industrial Crops and Products. 2017; 97 ():56-64.
Chicago/Turabian StyleCamille Goudenhooft; Alain Bourmaud; Christophe Baley. 2017. "Varietal selection of flax over time: Evolution of plant architecture related to influence on the mechanical properties of fibers." Industrial Crops and Products 97, no. : 56-64.
Christophe Baley; Antoine Kervoëlen; Antoine Le Duigou; Camille Goudenhooft; Alain Bourmaud. Is the low shear modulus of flax fibres an advantage for polymer reinforcement? Materials Letters 2016, 185, 534 -536.
AMA StyleChristophe Baley, Antoine Kervoëlen, Antoine Le Duigou, Camille Goudenhooft, Alain Bourmaud. Is the low shear modulus of flax fibres an advantage for polymer reinforcement? Materials Letters. 2016; 185 ():534-536.
Chicago/Turabian StyleChristophe Baley; Antoine Kervoëlen; Antoine Le Duigou; Camille Goudenhooft; Alain Bourmaud. 2016. "Is the low shear modulus of flax fibres an advantage for polymer reinforcement?" Materials Letters 185, no. : 534-536.