Pierre Ouagne

• Professor
• Professor at École Nationale d'Ingénieurs de Tarbes

Currently, composite materials are made from synthetic reinforcing materials such as glass, carbon and aramid fibers. However, the growing awareness of environmental impact has led to the development of composite materials based on lignocellulosic fibers such as flax. These biocomposites are attractive alternatives due to their low density, excelle...

The present study examined the effect of biobased molecules grafted onto wrapped flax rovings on the mechanical properties of fabrics designed for epoxy-based biocomposites, aiming to optimize fiber/matrix adhesion. Biobased solutions, such as tannins from quebracho, were used to treat wrapped flax rovings in comparison to a non-biobased aminosilan...

This study aims at better understanding the damage and fracture kinetics in flax fibre elements at both the unitary and bundle scales, using an experimental setup allowing optical observation at high recording rate in the course of tensile loading. Defects and issues from flax unitary fibre extraction are quantitated using polarized light microscop...

This study aims at better understanding the damage and fracture kinetics in flax fibres elements at both the unitary and bundle scales using an experimental setup allowing optical observation at high recording rate in the course of tensile loading. Defects issues from flax unitary fibre extraction are quantitated using polarized light microscopy. T...

In this work, we investigate the influence of noncircularity along with cross-sectional area evolution on the measurement of the mechanical properties of elementary fibres. First, we focus on the cross-sectional area measurement and compare the circular assumption with the elliptical one using an ombroscopic device that allows the measurement of th...

Hemp is finding a strong renewal of interest in the production of fine fibers for garment textiles. This resource of long-line fibers would come as a complement to the highly demanded flax fibers, whose large production in the north-west of Europe cannot be extended. In Normandy, where a complete industrial value chain exists for flax, it is intend...

This work focuses on the design and fabrication of a continuous filament made of flax yarn and bio-based thermoplastic polymer. For this purpose, the sheath-core process has been explored by using an extrusion laboratory line equipped with a wire coating die to manufacture a flax core coated with PLA. The polymer properties were investigated (therm...

Flax fibres are valuable reinforcements for tomorrow's composites. However, defects called kink-bands, which mainly appear on fibres during the extraction and transformation phases, might affect their mechanical properties. Defects induced pores, within the kink-band are investigated in this work. They were morphologically explored using synchrotro...

Due to the ever-growing demand for bast fibres for technical and garment textiles, complementary sources to textile flax, whose cultivation in western Europe cannot really be extended, need to be proposed. In this study, the interest in harvesting and processing linseed flax straw is studied for geotextile applications. The main critical stages of...

The creation and ultrastructure of kink-bands in flax fibres are key issues for developing more and more performing biobased composite materials. Nevertheless, despite many hypotheses and structural characterisation, the exact origin of kink-bands and the moment they appear remain unexplained. Here, by using cutting-edge techniques such as microtom...

Currently, the effects of global warming are one of the most important topics on the agendas of all governments and international economic and scientific organisations on the planet. Temperatures and rainfall will be especially subjected to increasing deregulation, and thus crop yields will be affected according to geographic location. Cellulosic m...

Hemp is a sustainable source of natural fibres that can contribute to meet the increasing demand for technical applications in the textile and the composite sectors. Continuous reinforcements can be produced using the existing flax machinery, initially developed for textile purposes. To achieve competitive and economically viable fibre yields and a...

Linseed flax is an oilseed producing crop but its stems are rich in high potential fibers. However, linseed flax is not highly promoted for fiber application purposes. It is mainly due to the lack of technical knowledge regarding good quality fiber extraction from linseed stems. In this study, a fiber extraction device has been used to extract fibe...

Despite the increased use of hemp fiber, negligible attention has been given to upgrade the hemp hurd, which constitutes up to 70 wt % of the hemp stalk and is currently considered a low-value byproduct. In this work, valorization of hemp hurd was performed by reductive catalytic fractionation (RCF) in the presence of a metal catalyst. We found an...

Recycling of thermoplastic composites has drawn a considerable attention in the recent years. However, the main issue with recycled composites is their inferior mechanical properties compared to the virgin ones. In this present study, an alternative route to the traditional mechanical recycling technique of thermoplastic composites has been investi...

Increasing the production of high-performance natural fibres that minimise their impact on the environment is a challenge that flax (Linum usitatissinum L.) cannot address alone. In flax traditional production territories, hemp (Cannabis sativa L.) can be a complementary source of high added value fibres if their yield of long line fibres can be ma...

Linseed flax is a multipurpose crop. It is cultivated for its seeds and particularly for its oil. The main contributors for this crop are Canada, France and Belgium. In general, straws of linseed flax are buried in the fields or burnt. However, these solutions are not good practices for the environment and from an economical point of view. In this...

This work was conducted to investigate the potential of fibers extracted from linseed flax straw for geotex-tile applications. Four different batches of linseed flax were studied, having different dew retting durations (i.e., from 0 to 14 weeks). Furthermore, a method comprising horizontal breaker rollers, a thresher and then a breaking card was us...

Following their mechanical extraction, the fibers coming from the banana pseudo-stem are coarse and the inter fiber cohesive substances need to be removed before their transformation into textile yarns/technical textiles. To reach this objective, dry-coarse banana fibers previously extracted using compressive rollers are treated using an oil-water-...

Retting of fibrous plants such as flax is an essential step in the extraction of fibre bundles and their transformation into textiles and reinforcement fabrics for use in garments and composites. Dew-retting is traditionally performed from Northwest France to the Netherlands, as the climate is highly favourable for this process. Hemp is a plant tha...

A versatile twin-screw extrusion process to provide an efficient thermo-mechano-chemical pre-treatment on lignocellulosic biomass before using it as source of mechanical reinforcement in fully bio-based fiberboards was developed. Various lignocellulosic crop by-products have already been successfully pre-treated through this process, e.g., cereal s...

Resistance to impact thrust is one of the most important requirement along with many others for defining suitable applications of any composite materials. In this present work, the influence of composite architecture and composite interfacial bonding strength on the impact performance of flax reinforced PP composites have been investigated. In this...

The tow-sliding defect also referred to as gapping that appears during complex shaping of woven reinforcements is due to a loss of cohesion in the fabric. The cohesion of the fabric tends to keep the tows from sliding under tension. This cohesion depends on the frictional behavior of the tows mainly. Other factors such as the weave of the fabric, t...

Flax-PP based thermally bonded roving (TBR) has a unique structure where the flax fibres remain twist-free and fully aligned along the roving axis. The present study describes an experimental investigation on the low velocity impact (LVI) behaviour of the TBR based woven fabric composites and compares the same with plain woven glass fabric reinforc...

This work assesses the potential of nettle (Urtica dioica L.) fibers produced on contaminated lands for composite applications. The nettles studied in this work grew spontaneously and in a prevalent manner in poplar short rotation coppice planted for the phytomanagement of a land contaminated by traces of metals. Results show that the contaminant c...

Flax (Linum usitatissimum L.) has been grown since the antiquity for tis ability to provide fibres for the confection of clothes. It has also been used for the production of technical fabrics such as sails for example. In the 20th century, and particularly in Europe, the vegetal fibres such as flax were progressively replaced by synthetic fibres fr...

In western Europe, hemp is mainly cultivated for the seeds and the fibre rich straws, randomly aligned following the harvesting with a combine harvester. The straws are mainly valorised for low added value products such as pulp for paper and for insulation. They are also valorised in low property short fibre composites. With the view to use hemp fi...

The use of natural fibre reinforced composites such as flax fibre / polypropylene is in a constant expansion particularly in automotive and marine industries due to their good mechanical properties, low density and thus, lightness, low environmental impact, low cost, recyclability, renewable properties of flax fibres and a minimum energy intake dur...

The use of composite materials reinforced by flax fibres has been increasing steadily over the last 20 years. These fibres show attractive mechanical properties but also some particularities (naturally limited length, presence of a lumen, fibres grouped in bundles in the plant, complex surface properties and composition). An analysis of the availab...

Cultivated primarily for its seeds, oleaginous flax could also be valued for the different fractions that can be extracted from the straw. However, as the straws are not harvested with the same technique and care than for the textile flax, the classical scutching technique cannot be used. As a consequence, an “all fibre” device was used to perform...

In this study, fiberboards were produced from shives collected after continuous fiber mechanical extraction from oleaginous flax straw. Fiberboards were produced through thermo-pressing, and their mechanical and thermo-mechanical properties were studied, as well as their water resistance. The influence of one pretreatment for shives and lignin addi...

This work assesses the potential of stinging nettle (Urtica dioica L.) growing on trace element contaminated soils to produce fibres for material applications. The nettles studied in this work grew spontaneously and dominated the vegetation cover in poplar short rotation coppices planted for the phytomanagement of lands contaminated by trace elemen...

Fibres from hemp stems can be extracted through different mechanical processes following dew or water retting etc. Extraction processes generally have a significant impact on mechanical and morphological properties of the fibres. In this study, hemp fibres are extracted following three different ways. In the first route hemp fibres are extracted fr...

This work of a preliminary nature has for goal to investigate the potential of the linseed flax straw for industrial valorization in technical textiles. The impact of two extraction systems (“all fiber” extraction device and a scutching/hackling device) was investigated. In a first part of the paper, it was demonstrated that it is possible to extra...

We investigate the causes, kinematic and possible ways to prevent the tow-buckling defect during the complex shape-forming of a dry woven reinforcement. Macro-scale compression leads to wrinkles; we focus on a meso- scale phenomenon generated by a non-uniform axial compression of the tow due to in-plane bending. An experimental study is presented,...

In order to understand the causes and the formation process of the tow sliding defect, shape preforming tests were performed on a hemispherical punch. Variable orientation and blank holders’ pressure were investigated in order to assess the phenomena and a cohesion pull-out test was proposed to investigate the cohesion of the reinforcement which wa...

Amaranth is an annual herb native to temperate and tropical regions. It is a promising raw material for the biorefinery of whole plants. Looking at the large amounts of starch, proteins and squalene inside its seeds, the latter could find applications in many fields like the food, cosmetics and material industries. This study specifically investig...

The first step in the composite manufacturing process consists of forming a flat textile reinforcing structure into a 3D shape. The quality of the final composite part is affected by the presence of defects induced during the forming process. Loss of cohesion in the woven fibre network (intra-ply yarn sliding) is a frequent defect in the forming pr...

Dans cette étude, des panneaux agglomérés de fibres ont été produits à partir d’anas collectés après extraction mécanique des fibres libériennes de paille de lin oléagineux. Les panneaux ont été mis en œuvre par thermopressage. Leurs propriétés mécaniques et thermo-mécaniques ont été étudiées ainsi que leurs comportements vis-à-vis de l’eau. L’infl...

Cultivé principalement pour ses graines, le lin oléagineux pourrait également être valorisé pour les différentes fractions végétales qui peuvent être extraites de la paille. Cependant comme les pailles ne sont pas récoltées avec la même technique et le même soin que pour le lin textile, la technique classique de teillage ne peut pas être utilisée....

Manufacturing complex composite part via Liquid Composite Molding (LCM) processes involves preforming dry textile perform before injecting the liquid resin. The defect that may be encountered within the textile structure during preforming step decreases the expected mechanical properties of the composite part. The intra-ply yarn sliding is a defect...

The significant industrial development of non-woven biocomposites requires the implementation of environmentally and economically coherent end-of-life recycling solutions. In this study, we studied the recycling of a non-woven poly-(propylene)-flax composite by injection but also by thermo compression. For comparison, a material with the same archi...

Preforming is the first step to manufacture a complex composite part via Liquid Composite Moulding processes. The defects that may be encountered during this phase within the preform architecture may decrease the expected mechanical performances of the final part. The intra-ply yarn sliding is a defect frequently observed during preforming of a wov...

This work proposes to analyse the different aspects that should be taken into account from the fibre extraction from plants to the forming process to achieve correct part forming. The study will focus in a first extent on the impact of the textile operations leading to the yarn manufacturing. The properties of the flax fabric will then be associate...

During the complex shape forming of composite fibrous reinforcement, the planar bending of roving tows results in an out-of-plane deflection, along with a rotation on its central axis. The need to accurately follow and quantify the mechanism of formation of such defect has led us to consider two 3D imaging techniques, of which, have been tested and...

Preforming is the first step to manufacture a complex composite part via Liquid Composite Moulding processes.The defects that may be encountered during this phase within the preform architecture may decrease the expected mechanical performances of the final part. The intra-ply yarn sliding is a defect frequently observed during preforming of a wove...

In this study, fiberboards were produced from shives collected after continuous fiber mechanical extraction from oleaginous flax straw. Fiberboards were produced through thermo-pressing, and their mechanical and thermomechanical properties were studied, as well as their water resistance. The influence of two pretreatments for shives and lignin addi...

The main objective of this collaborative work is to characterize the influence of the processing stages of industrial hemp on the fibre properties. Transformation processes well suited for composite reinforcing textiles are considered. The work focuses on the different stages along the transformation chain of hemp, from the straw retting to the pre...

The main objective of this collaborative work is to characterize the influence of the processing stages of industrial hemp on the fibre properties. Transformation processes well suited for composite reinforcing textiles are considered. The work focuses on the different stages along the transformation chain of hemp, from the straw retting to the pre...

Cultivated primarily for its seeds, oleaginous flax could also be valued for the different fractions that can be extracted from the straw. However, as the straws are not harvested with the same technique and care than for the textile flax, the classical scutching technique cannot be used. As a consequence, an “all fibre” device was used to perform...

Natural cellulosic fibres such as flax fibres present interesting mechanical properties as well as biodegradability, and by-products, such as short flax fibres, could be used to produce geotextiles to stabilise soils. Today, geotextiles are often made of coir fibres, which have a high lignin percentage leading to their slow degradation in soil. Fib...

This study examines the ability to develop composite parts with complex geometries without defect. An experimental approach is used to identify and quantify the defects such as buckling caused by the bending of rovings during forming. Solutions are developed to obtain a complex shape such as a tetrahedron without any defect by using specially...

The use of natural fibres for technical advanced products such as composites is widely increasing with the view to reduce the impact of the material throughout its life cycle on the environment. Some work has been performed on natural fibre based reinforcement textiles for composite materials. The mechanical and the formability behaviours of woven...

During the manufacturing of composite complex shape parts, defects such as tow buckles characterised by out of plane elevation may appear. The parameters controlling the appearance and growth of the defect are not completely understood and need to be investigated. A device capable of reproducing tow buckles has been used to study the tow buckling p...

This study examines the ability to develop composite parts with complex geometries without defect. An experimental approach is used to identify and quantify the defects such as buckling caused by the bending of rovings during forming. Solutions are developed to obtain a complex shape such as a tetrahedron without any defect by using specially desig...

This work investigates the tow buckling defect that may take place during the forming of complex shapes. The defect is studied independently of the process with a device specially designed. A specific instrumentation was associated to the device. Structure light interferometry was chosen to measure the elevation of the tows exhibiting the buckling...

The preforming step, which is the first stage of the Resin Transfer Molding process, has been analyzed by many experimental or numerical approaches in the literature for reinforcements made of synthetic fibers. The complex mechanical behavior of a flax-based plain weave fabric was studied with the view to investigate its formability. Nonlinearities...

This paper investigates the flame retardant and mechanical properties of a flax woven fabric that can be used to prepare biocomposites. The flame retardant properties of the fabric are first considered using different ammonium phosphate salts and intumescent systems. It is demonstrated that satisfactory performances can be achieved using this appro...

This study concentrates on the possibility of forming complex shapes using the sheet forming process; a technique that could be used by the automotive industry due to interesting cost/cadencies ratio. Particularly investigated is the possibility of realizing a technical complex preform without defect from two different architecture commercial reinf...

The mechanical behaviour of flax/polylactic acid (flax/PLA) and flax/polypropylene (flax/PP) bio-composites exposed to a medical environment (disinfectant and cleaning treatments) is studied for a use as a semi-structural part. Immersion tests in the different cleaning products were performed for both bio-composites in order to measure the absorpti...

This study concentrates on the possibility of forming a complex shape such as a tetrahedron using two untwisted commercial flax based fabric reinforcements using the sheet forming process. As some of the defects such as tow buckles or tow sliding cannot be predicted and therefore anticipated using simulation techniques, an experimental approach has...

The preforming of dry reinforcements is the first step of the Resin Transfer Moulding process. To validate the feasibility to obtain a given shape, a simple model built from elastic isotropic shells coupled to axial connectors is proposed in this paper for the preforming of flax woven fabric. The mechanical behaviours of flax based fabrics characte...

Solutions to preform complex shapes such as a tetrahedron without any defect from flax based woven fabrics are investigated in this work. The first way to prevent the appearance of defects such as tow buckles consists in designing specific woven architecture fabrics. However, even if this solution was shown to be effective on the tetrahedron shape,...

During the forming, tow buckling (out of plane bending of tows) was observed in specific zones of the shape. This defect is highly depending of the process parameters and of the fabric. In order to predict the process parameters to avoid the tow buckling during the forming, it is necessary to identify precisely the different mechanisms at the origi...

Environmental interest lead researches in the valorization of local raw material. Some byproducts like flax tows and short hemp fibers could be valorized into biobased geotextiles. Per se, these geotextiles have limited life depending on the environment. Consequently, their mechanical performances during their life time are dependent of the mechani...

The bending behaviour of woven perform was investigated in order to better understand the formation of some defects during sheet forming such as wrinkling and tow buckling. The fabric composition considering hybrid and pure flax fabrics as well as some test conditions like relative humidity were examined. On the one hand, the results show a drop of...

To study the potential of flax tows in composite processing as an alternative to flax spun yarns, a flat flax tow consisting of aligned fibre bundles held together by a natural binder was used and characterised in tension under various conditions. The effect of the gauge length was studied on the dry reinforcement. The experimental results showed t...

With the view to minimise the impact on the environment and to produce structural parts with a good production-rate/cost-ratio, the sheet forming of woven flax based fabric was investigated in this study. A flax fibre plain-weave fabric has been used to form a complex tetrahedron shape. This shape is of particular interest as it contains several ge...

It is an important topic to measure the through-thickness permeability of fiber reinforcements as the resin flow in the thickness direction is widely employed in many composites manufacturing techniques. Continuous techniques for the permeability measurement by simultaneous fabric compaction and liquid flow have been recently proposed as an alterna...

Forming complex shape composite parts with a good production rate/cost ratio is of particular importance for the automotive industry. The sheet forming of woven reinforcements is a promising technique, especially if complex shapes with singularities such as case corners can be obtained. Due to the more and more important recycling needs, the use of...

This experimental work concerns the study of the preforming of a specific highly double curved geometry with a triple point (case corner) by the sheet forming process using powdered interlock reinforcement (G1151®). Three different punches (square box, prism, tetrahedron) were used in this study, each of them presenting highly double curved geometr...