M. Résultats-des, 131 3.3.1 Propriétés hygro-mécaniques des sous-couches pour diérentes humidités relatives obtenues par le modèle analytique, p.131

M. Karus and M. Kaup, Natural bres in the european automotive industry, J

J. Nichel and U. Riedel, Activities in biocomposites, Materials Today, vol.6, issue.4, p.4448, 2003.
DOI : 10.1016/S1369-7021(03)00430-9

C. Baley, Fibres naturelles de renfort pour matériaux composites, AM, vol.5130, p.112, 2004.

C. Baley, Analysis of the ax bres tensile behaviour and analysis of the tensile stiness increase, Composite Part A: Applied Science and Manufacturing, vol.33, issue.7, p.939948, 2002.

C. Baley, Contribution à l'étude de matériaux composites à matrice organique renforcés par ds bres de lin, Rapport HDR, 2003.

C. Baley, Y. Grohens, and I. Pillin, Etat de l'art sur les mat??riaux composites biod??gradables, Revue des composites et des matériaux composites avancés, p.135166, 2004.
DOI : 10.3166/rcma.14.135-166

K. Van-de-velde and P. Kiekens, Thermoplastic pultrusion of natural bre reinforced composites, Composite Structures, vol.54, issue.2-3, p.355360, 2001.

M. J. Van-den-oever, H. L. Bos, and M. Van-kemenade, Inuence of the physical structure of ax bres on the mechanical properties of ax bre reinforced polypropylene composites, Applied Composite Material, vol.7, issue.5, p.387402, 2000.

N. Defroidt, Assessment of the tensile properties of coir, bamboo and jute bre, Composites Part A: Applied Science and Manufacturing, vol.41, issue.5, p.588595, 2010.

A. K. Bledzki, A. Jaszkiewicz, and D. Scherzer, Mechanical properties of pla composites with man-made cellulose and abaca bres, Composites Part A: Applied Science and Manufacturing, vol.40, issue.4, p.404412, 2009.

S. Ochi, Development of high strength biodegradable composites using manila hemp ber and starch-based biodegradable resin, Composites Part A: Applied Science and Manufacturing, vol.37, issue.11, p.18791883, 2006.

F. Vilaseca, A. Valadez-gonzalez, P. J. Herrera-franco, M. À. Pèlach, J. P. López et al., Biocomposites from abaca strands and polypropylene. Part I: Evaluation of the tensile properties, Bioresource Technology, vol.101, issue.1, p.387395, 2010.
DOI : 10.1016/j.biortech.2009.07.066

M. Brahmakumar, C. Pavithran, and R. M. Pillai, Coconut bre reinforced polyethylene composites: eect of natural waxy surface layer of the bre on bre/matrix interfacial bonding and strength of composites, Composites Science and Technology, vol.65, pp.3-4563569, 2005.

S. V. Prasad, C. Pavithran, and P. K. Rohatgi, Alkali treatment of coir bres for coir-polyester composites, Journal of Materials Science, vol.18, issue.5, p.14431454, 1983.

N. E. Zafeiropoulos, D. R. Williams, C. A. Baillie, and F. L. Matthews, Engineering and characterisation of the interface in ax bre/polypropylene composite materials. part i: Development and investigation of surface treatments, Composites Part A: Applied Science and Manufacturing, issue.8, p.3310831093, 2002.

N. E. Zafeiropoulos, C. A. Baillie, and J. M. Hodgkinson, Engineering and characterisation of the interface in ax bre/polypropylene composite materials. part ii: The eect of surface treatments on the interface, Composites Part A: Applied Science and Manufacturing, vol.33, issue.9, p.11851190, 2002.

A. L. Duigou, I. Pillin, P. Bourmaud, A. Davies, and C. Baley, Eect of recycling on mechanical behaviour of biocompostable ax/poly(l-lactide) composites, Composites Part A: Applied Science and Manufacturing, vol.39, issue.9, p.14711478, 2008.

P. Wambua, J. Ivens, and I. Verpoest, Natural bres: can they replace glass in bre reinforced plastics? Composites Science and Technology, p.12591264, 2003.

A. G. Facca, M. T. Kortschot, and N. Yan, Predicting the elastic modulus of natural bre reinforced thermoplastics, Composites Part A: Applied Science and Manufacturing, vol.37, issue.10, p.16601671, 2006.

P. Mutjé, A. Lòpez, M. E. Vallejos, J. P. Lòpez, and F. Vilaseca, Full exploitation of cannabis sativa as reinforcement/ller of thermoplastic composite materials, Baley. Investigations on the recycling of hemp and sisal bre reinforced polypropylene composites. Polymer Degradation and Stability, pp.369377-9210341045, 2007.

A. Bourmaud and C. Baley, Rigidity analysis of polypropylene/vegetal bre composites after recycling, Polymer Degradation and Stability, vol.94, issue.3, p.297305, 2009.

M. Jacob, K. T. Thomas, and S. Varughese, Mechanical properties of sisal/oil palm hybrid ber reinforced natural rubber composites, Composites Science and Technology, vol.64, issue.78, p.955965, 2004.

Y. Li, Y. Mai, and L. Ye, Sisal bre and its composites: a review of recent developments, Composites Science and Technology, vol.60, issue.11, p.20372055, 2000.

F. Corrales, F. Vilaseca, M. Llop, J. Giron-?-s, and J. A. , M?ndez, and P. Mutj? Chemical modication of jute bers for the production of green-composites, Journal of Hazardous Materials, vol.144, issue.3, p.730735, 2007.

T. Doan, S. Gao, and E. Mäder, Jute/polypropylene composites. part i: Eect of matrix modication, Composites Science and Technology, vol.66, issue.78, p.952963, 2006.

T. Doan, H. Brodowsky, and E. Mäder, Jute bre/polypropylene composites. part ii: Thermal, hydrothermal and dynamic mechanical behaviour, Composites Science and Technology, vol.67, issue.13, p.27072714, 2007.

K. Goda, M. S. Sreekala, A. Gomes, T. Kaji, and J. Ohgi, Improvement of plant based natural bers for toughening green compositeseect of load application during mercerization of ramie bers, Composites Part A: Applied Science and Manufacturing, issue.12, p.3722132220, 2006.

F. Windels, Des composites renforcés de bres végétales. Fiche Technique CCI Agro-Industrie, 2007.

D. Gay, Matériaux composites. Hermes Science -Paris -Lavoisier, 2005.

D. Wyart, Les polymères biodégradables, AM, vol.3579, p.121, 2007.

A. Bergeret and P. Krawczak, Liaison renfort/matrice -comportement des composites, AM, vol.5307, p.119, 2006.

M. D. Beg and K. L. Pickering, Reprocessing of wood fibre reinforced polypropylene composites. Part II: Hygrothermal ageing and its effects, Composites Part A: Applied Science and Manufacturing, vol.39, issue.9, pp.1565-1571, 2008.
DOI : 10.1016/j.compositesa.2008.06.002

M. D. Beg and K. L. Pickering, Reprocessing of wood fibre reinforced polypropylene composites. Part I: Effects on physical and mechanical properties, Composites Part A: Applied Science and Manufacturing, vol.39, issue.7, pp.1091-1100, 2008.
DOI : 10.1016/j.compositesa.2008.04.013

J. Vallade, Structure et développement de la plante. Morphogénèse et biologie de la reproduction des angiospermes, 1999.

K. Persson, Micromechanical modelling of wood and bre properties, 2000.

A. Béakou, R. Ntenga, J. Lepetit, J. A. Atéba, and L. O. Ayina, Physico-chemical and microstructural characterization of "rhectophyllum camerunense" plant ber, Composites Part A: Applied Science and Manufacturing, vol.39, issue.1, p.6774, 2008.

J. P. Thiery, Mise en évidence des polysaccharides sur coupes nes en microscopie électronique, J. Microsc, vol.6, p.987, 1967.

V. Bossuyt, Etude de la structure et des propriétés mécaniques de la bre de lin, 1941.

C. T. Brett and K. W. Wamdron, Physiology and biochemistry of plant cell walls, 1996.
DOI : 10.1007/978-94-010-9641-6

T. Nilsson and P. J. Gustafsson, Inuence of dislocation and plasticity on the tensile behaviour of ax and hemp bres, Composites: Part A, vol.38, p.17221728, 2007.

R. D. Preston, The physical biology of plant cell walls, 1974.

D. Fengel, The ultrastructure of cellulose from wood, Wood Science and Technology, vol.16, issue.No. 1, p.203217, 1969.
DOI : 10.1007/BF00367212

H. F. Jang, Measurement of bril angle in wood fbres with polarization confocal microscopy, Journal of pulp and paper science, vol.24, p.224230, 1998.

H. Lichtenegger, A. Reiterer, S. E. Tschegg, and P. Fratzl, Variation of cellulose microbril angles in softwoods and hardwoods -a possible strategy of mechanical optimization, Journal of structural biology, vol.128, p.257269, 1999.

A. K. Bledzki and J. Gassan, Composites reinforced with cellulose based bres, Progress in Polymer Science, vol.24, issue.2, p.221274, 1999.

A. Bergander and L. Salmèn, Cell wall properties and their eects on the mechanical properties of bers Observations of the tensile properties of ultimate cells of some plant bres, Journal of Materials Science, vol.37, issue.112, pp.151156-58651656, 1967.

P. S. Mukherjee and K. G. Satyanarayana, Structure and properties of some vegetable bres, Journal of Materials Science, vol.21, issue.10, p.5156, 1007.

P. S. Mukherjee and K. G. Satyanarayana, An empirical evaluation of structureproperty relationships in natural bres and their fracture behaviour, Journal of Materials Science, vol.21, pp.41624168-41624178, 1986.

H. P. Stout and J. A. Jenkins, Comparative strengths of some bast and leaf bres, Annales Textiles Belges, vol.4, p.231251, 1955.

H. H. Wang, J. G. Drummond, S. M. Reath, K. Hunt, and P. A. Watson, An improved bril angle measurement method for wood bres, Wood Science and Technology, vol.34, issue.10, p.493503, 1007.
DOI : 10.1007/s002260000068

S. K. Batra, Handbook of ber chemistry -Other long vegetable bers, 1998.

N. Richard and . Tenga, Modélisation multi-échelle et caractérisation de l'anisotropie élastique de bres végétales pour le renforcement de matéraiux composites, 2007.

R. M. Rowell, J. S. Han, and J. Rowell, Characterization and factors eecting ber properties, Natural Polymers and Agrobers Bases Composites, p.115134, 2000.

M. Mohan-rao and K. Rao, Extraction and tensile properties of natural bers: Vakka, date and bamboo, Composite Structures, vol.77, issue.3, pp.288-295, 2007.

J. Gassan and A. K. Bledzki, Modication methods on natural bres and their inuence on the properties of the composites, Plastics, vol.54, p.25522557, 1996.

H. P. Khalil, H. D. Rozman, M. N. Ahmad, and H. Ismail, Acetylated plant-bre reinforced polyester composites: a study of mechanical, hydrothermal and aging characteristics, Polym Plast technol Eng, vol.19, p.757781, 2000.

H. Lilhot and J. M. Lawther, Comprehensive Composite Materials" -Natural cellulose ber -Chap. 1-10, 2000.

M. Le-troedec, D. Sedan, C. Peyratout, J. P. Bonnet, A. Smith et al., Inuence of various chemical treatments on the composition and structure of hemp bres, Composites Part A: Applied Science and Manufacturing, vol.39, issue.3, p.514522, 2008.

D. A. Goring and T. E. Timelle, Molecular weight of native cellulose, TAPPI J, vol.45, p.454459, 1962.

J. Warwicker, Swelling of cotton in alkalis and acids, Journal of Applied Polymer Science, vol.13, issue.1, p.4154, 1969.
DOI : 10.1002/app.1969.070130106

L. Salmèn, Micromechanical understanding of the cell-wall structure, Comptes Rendus Biologies, vol.327, issue.9-10, p.873880, 2004.
DOI : 10.1016/j.crvi.2004.03.010

I. Sakurada, Y. Nukushina, and T. Ito, Experimental determination of the elastic modulus of crystalline regions in oriented polymers, Journal of Polymer Science, vol.57, issue.165, p.651660, 1962.
DOI : 10.1002/pol.1962.1205716551

T. Nishino, K. Takano, and K. Nakamae, Elastic modulus of the crystalline regions of cellulose polymorphs, Journal of Polymer Science Part B: Polymer Physics, vol.33, issue.11, p.16471651, 1995.
DOI : 10.1002/polb.1995.090331110

E. Marklund and J. Varna, Modeling the hygroexpansion of aligned wood ber composites, Composites Science and Technology, vol.69, issue.78, p.11081114, 2009.

I. D. Cave, Modelling moisture-related mechanical properties of wood Part I: Properties of the wood constituents, Wood Science and Technology, vol.70, issue.11, p.7586, 1978.
DOI : 10.1007/BF00390012

W. J. Cousins, Elastic modulus of lignin as related to moisture content, Wood Science and Technology, vol.4, issue.2, p.917, 1976.
DOI : 10.1007/BF00376380

R. J. Astley, J. Harrington, and K. A. Stol, Mechanical modelling of wood microstructure , an engineering approach, IPENZ Transaction, vol.24, issue.1, 1997.

Y. Tamaki, T. Konishi, M. Fukuta, and M. Tako, Isolation and structural characterisation of pectin from endocarp of Citrus depressa, Food Chemistry, vol.107, issue.1, pp.352-361, 2008.
DOI : 10.1016/j.foodchem.2007.08.027

C. Rihouey, C. Morvan, I. Borissova, A. Jauneau, M. Demarty et al., Structural features of cdta-soluble pectins from ax hypocotyls, Carbohydrate Polymers, vol.28, issue.2, p.159166, 1995.

E. A. Davis, C. Derouet, C. H. Penhoat, and C. Morvan, Isolation and an N.M.R. study of pectins from flax (linum usitatissimum L.), Carbohydrate Research, vol.197, pp.205-215, 1990.
DOI : 10.1016/0008-6215(90)84143-I

B. Mortaigne, Vieillissement des composites -mécanismes et méthodologie d'étude. Techniques de l'Ingénieur, AM, vol.5320, p.121, 2005.

W. Wang, M. Sain, and P. A. Cooper, Hygrothermal weathering of rice hull/HDPE composites under extreme climatic conditions, Polymer Degradation and Stability, vol.90, issue.3, p.540545, 2005.
DOI : 10.1016/j.polymdegradstab.2005.03.014

M. D. Beg and K. L. Pickering, Mechanical performance of kraft bre reinforced polypropylene composites: Inuence of bre length, bre beating and hygrothermal ageing, Composites Part A: Applied Science and Manufacturing, issue.11, pp.391748-1755, 2008.

M. D. Beg and K. L. Pickering, Accelerated weathering of unbleached and bleached kraft wood bre reinforced polypropylene composites, Polymer Degradation and Stability, issue.10, p.9319391946, 2008.

W. J. Cousins, Young's modulus of hemicellulose as related to moisture content, Wood Science and Technology, vol.4, issue.2, p.161167, 1978.
DOI : 10.1007/BF00372862

R. Neagu and E. Gamstedt, Modelling of eects of ultrastructural morphology on the hygroelastic properties of wood bres, Journal of Materials Science, issue.24, p.421025410274, 2007.

R. Hill, Elastic properties of reinforced solids: Some theoretical principles, Journal of the Mechanics and Physics of Solids, vol.11, issue.5, p.357372, 1963.
DOI : 10.1016/0022-5096(63)90036-X

R. Hill, Theory of mechanical properties of bre-strengthened materials: I. elastic behaviour, Journal of the Mechanics and Physics of Solids, vol.12, issue.4, 1964.

J. M. Whitney, Elactic moduli of unidirectionnal composites with anisotropic laments, Journal of composite materials, vol.1, p.188193, 1967.

Z. Hashin, Analysis of Properties of Fiber Composites With Anisotropic Constituents, Journal of Applied Mechanics, vol.46, issue.3, pp.543-550, 1979.
DOI : 10.1115/1.3424603

W. Rosen and Z. Hashin, Eective thermal expansion coecients and specic heats of composite materials, International Journal of Engineering Science, vol.8, issue.2, p.157173, 1970.

R. M. Christensen and K. H. Lo, Solutions for eective shear properties in three phase sphere and cylinder models, Journal of the Mechanics and Physics of Solids, vol.27, issue.4, p.315330, 1979.

Z. Hashin and W. Rosen, The elastic moduli of ber-reinforced material, J. Appl Mech, vol.31, p.223232, 1970.

E. Marklund, J. Varna, C. Neagu, and G. , Stiness of aligned wood ber composites: Eect of microstructure and phase properties, Journal of Composites Materials, pp.42-222377, 2008.

E. Hervé and A. Zaoui, Elastic behaviour of multiply coated bre-reinforced composites, International Journal of Engineering Science, vol.33, issue.10, p.14191433, 1995.

H. Yamamoto, A model of the anisotropic swelling and shrinking process of wood. Part 1. Generalization of Barber's wood fiber model, Wood Science and Technology, vol.33, issue.4, p.311325, 1999.
DOI : 10.1007/s002260050118

H. Yamamoto, F. Sassus, M. Ninomiya, and J. Gril, A model of anisotropic swelling and shrinking process of wood. part ii: A simulation of shrinking wood, Wood Science and Technology, vol.35, issue.1, p.167181, 2001.

N. Barber, A theorical model of shrinking wood, Holzforschung, vol.22, p.97103, 1968.

N. Barber and B. Meylan, The anisotropic shrinkage of wood. a theorical model, Holzforschung, vol.19, p.146156, 1964.

C. Jolicoeur and A. Cardou, Analytical Solution for Bending of Coaxial Orthotropic Cylinders, Journal of Engineering Mechanics, vol.120, issue.12, p.25562574, 1994.
DOI : 10.1061/(ASCE)0733-9399(1994)120:12(2556)

J. Mercier, Prise en compte du vieillissement et de l'endommagement dans le dimensionnement de structures en matériaux composites, 2006.

L. Benabou and G. Duchanois, Modelling of the hygroelastic behaviour of a woodbased composite for construction, Composites Science and Technology, vol.67, issue.1, p.4553, 2007.

D. Derome, model for hysteretic moisture behaviour of wood, Proceedings of the Nordic Symposium on Building Physics, p.959966, 2008.

B. Coasen, K. E. Gubbins, and R. J. Pellenq, Domain theory for capillarry condensation hysteresis, Phys. Rev. B, issue.9, p.31934, 2005.

H. Qing and L. M. Jr, 3d hierarchical computational model of wood as a cellular material with bril reinforced, heterogeneous multiple layers, Mechanics of Materials, vol.41, issue.9, p.10341049, 2009.

J. Fahlén and L. Salmèn, Cross-sectional structure of the secondary wall of wood bers as aected by processing, Journal of Materials Science, vol.38, issue.10, p.1191261021174118468, 1023.

J. C. Halpin and J. L. Kardos, Halpin-tsai equations-review, Polym. Eng.Sci, vol.16, pp.344-352, 1976.

H. Qing and L. Mishnaevsky, Moisture-related mechanical properties of softwood: 3D micromechanical modeling, Computational Materials Science, vol.46, issue.2, p.310320, 2009.
DOI : 10.1016/j.commatsci.2009.03.008

K. Charlet, Contribution de l'étude de composites unidirectionnels renforcés par des bres de lin : relation entre la microstructure de la bre et ses propriétés mécaniques, 2006.

K. Charlet, J. P. Jernot, S. Eve, M. Gomina, and J. Bréard, Multi-scale morphological characterisation of ax: from the stem to the brils, Carbohydrate Polymers, vol.82, p.5461, 2010.

C. Baley, C. Morvan, and Y. Grohens, Influence of the Absorbed Water on the Tensile Strength of Flax Fibers, Macromolecular Symposia, vol.222, issue.1, pp.195-202, 2005.
DOI : 10.1002/masy.200550425

H. L. Bos and A. M. Donald, In situ esem study of the deformation of elementary ax bres, Journal of Materials Science, vol.34, issue.10, p.302930341004650126890, 1023.

J. Roland, M. Mosiniak, and D. Roland, Dynamique du positionnement de la cellulose dans les parois des bres textiles du lin (linum usitatissimum) Acta botanica gallica, p.463484, 1995.
DOI : 10.1080/12538078.1995.10515271

P. J. Van-soest, Use of detergents in the analysis of brous feeds. part ii: A rapid method for the determination of ber and lignin, J. Assoc. O. Agric. Chem, vol.46, p.829835, 1963.

P. J. Van-soest and R. Wine, Use of detergents in the analysis of brous feeds. part iv: Determination of plant cell-wall constituents, J. Assoc. O. Anal. Chem, vol.50, p.5055, 1967.

P. J. Van-soest and R. H. Wine, Determination of lignin and cellulose in aciddetergent ber with permanganate, J. Assoc. O. Anal. Chem, vol.51, p.780785, 1968.

A. Bismark, I. Aranberri-askargota, and J. Springer, Surface characterization of ax hemp and cellulose bers -surface properties and the water uptake behaviour, Polymer Composite, vol.23, p.872894, 2002.

I. Lapierre and P. Belmont, Bilan écologique du lin de la graine au tissu, Ecole Nationale Supérieure des Arts et Industrie Textiles de Roubaix, 1994.

V. Tserki, N. E. Zafeiropoulos, F. Simon, and C. Panayiotou, A study of the effect of acetylation and propionylation surface treatments on natural fibres, <ce:title>ACMC/SAMPE Conference on Marine Composites (MarComp) 2003</ce:title> <xocs:full-name>ACMC/SAMPE Conference on Marine Composites (MarComp) 2003</xocs, pp.1110-1118, 2005.
DOI : 10.1016/j.compositesa.2005.01.004

D. N. Hon, A new dimensional creativity in lignocellulosic chemistry, 1996.

K. Oksman, High quality ax bre composites manufactures by the resin transfert moulding process, Journal of reinforced plastics and composites, vol.20, p.621627, 2001.

M. Baiardo, M. Zini, and E. Scandola, Flax bre-polyester composites, Composites Part A: Applied Science and Manufacturing, vol.35, issue.6, p.703710, 2004.
DOI : 10.1016/j.compositesa.2004.02.004

S. Marais, F. Gouanvé, A. Bonnesoeur, J. Grenet, F. Poncin-epaillard et al., Unsaturated polyester composites reinforced with ax bers: eect of cold plasma and autoclave treatments on mechanical and permeation properties, Composites Part A: Applied Science and Manufacturing, issue.7, pp.36975-986, 2005.

V. Cray, Norsodyne g703 -résine polyester insaturé, 2010.

C. Geneau, Procédé d'élaboration d'agraomateriau composite naturel par extrusion bivis et injection moulage de tourteau de tournesol, 2006.

J. Cranck, The mathematics of diusion -Second edition, 1975.

G. Park, Transport principles -solution, diusion and permeation in polymer membranes, synthetic membranes : science, engineering and application. Reidel, 1986.

F. Gouanvé, S. Marais, A. Bessadok, D. Langevin, and M. Métayer, Kinetics of water sorption in ax and pet bers, European Polymer Journal, vol.43, issue.2, p.586598, 2007.

A. Angot, Compléments de mathématiques, Cinquième édition. Collection technique et scientique du CNET, 1965.

A. Stamboulis, C. A. Bailli, and T. Peijs, Effects of environmental conditions on mechanical and physical properties of flax fibers, Composites Part A: Applied Science and Manufacturing, vol.32, issue.8, pp.1105-1115, 2001.
DOI : 10.1016/S1359-835X(01)00032-X

A. Roudier, K. Charlet, F. Moreno, E. Toussaint, C. Géneau-sbartaï et al., Caractérisation des propriétés biochimiques et hygroscopiques d'une bre de lin, 2010.
DOI : 10.1051/mattech/2012044

A. Roudier, A. Béakou, and E. Toussaint, Modelling of the hygro-mechanical behavior of ax bres, 2011.

Z. Hashin, On elastic behaviour of bre reinforced materials of arbitrary transverse phase geometry, Journal of the Mechanics and Physics of Solids, vol.13, issue.3, p.119134, 1965.