• Pierre Blanchet Laval University
  • Alizera Kaboorani Kaboorani
  • Cecilia Bustos


yellow birch wood, mechanical properties, drying method, nanoindentation(NI), dynamic mechanical analysis (DMA), yellow birch


Conventional kiln and vacuum drying are commonly used in industry to dry wood. In this research, an attempt was made to develop a better understanding of the effects of both drying methods on the mechanical properties of wood at the ultra-structure and cellular structure levels. Dynamic mechanical analysis (DMA) and nanoindentation (NI) were used together with standard static bending tests according to ASTM D143 to assess the respective effects of both drying methods on the performance of yellow birch (Betula alleghaniensis Brit.) wood, an important species in the Canadian wood industry. Measurements of equilibrium moisture content (EMC) at different relative humidity (RH) levels showed that vacuum drying consistently yielded higher EMC values.  Vacuum-dried wood also exhibited superior MOE and MOR performance. Tests conducted by DMA demonstrated that the chemical structure of wood had undergone more changes during conventional kiln drying than during vacuum drying. The elastic modulus and hardness measured by the nanoindentation technique revealed that the impact of wood drying can be detected at the cell wall level as well. The results of this study showed that special attention should be paid to the effects of specific drying methods on the chemical structure of wood, as the chemical changes occurring in the kiln impact on the quality of the final products.   


Avramidis S, Liu M, Neilson BJ(1994) Radio-frequency/vacuum drying of softwoods: drying of thick western red cedar with constant electrode voltage. Forest Prod. J. 44(1):41-47.

Backman AC, Lindberg KAH (2001) Difference in wood material responses for radial and tangential direction as measured by dynamic mechanical thermal analysis. Journal of Material Science 36 (15): 3777–3783.

Barefoot AC, Hitchings RG, Ellwood EL(1965) Wood characteristics of kraft paper properties of four selected loblolly pines. III. Effect of fiber morphology on pulp. Tappi 49:137–47.

Berry S, Roderick M(2005) Plant-water relations and the fibre saturation point. New Phytologist 168:25–37.

Bowyer JL, Shmulsky R , Haygreen JG (2003) Forest Products and Wood Science; Iowa State Press: Ames, IA, USA.

Cai Y, Hayashi K (2007) New monitoring concept of moisture content distribution in wood during RF/va¬cuum drying. Journal of Wood Science 53:1-4.

Cheng YT, Cheng CM (2004) Scaling, dimensional analysis, and indentation measurements,” Materials Science and Engineering Reports: R44: 91.

Curling, SF, Winandy JE, Clausen CA(2002) Experimental method to quantify progressive stages of decay of wood by basidiomycete fungi. International Biodeterioration and Biodegradation 49: 13-19.

Edvardsen K, Sandland KM (1999) Increased drying temperature – Its influence on the dimensional stability of wood, European Journal of Wood and Wood Products 57(3):207-209.

Fengel D, Wegener G (1989) Wood: Chemistry, Ultrastructure, Reactions. De Gruyter, Berlin.

Fisher-Cripps AC (2011) Nanoindentation. Springer, New York, USA.

Hansson L, Antti AL (2006) The effect of drying method and temperature level on the hardness of wood Journal of Materials Processing Tech. 171(3): 467-470.

He M J, Chen WX, Dong XX (2000) Macromolecular Physics. Fudan University Publishing House, Shanghai, China 224–228 (in Chinese).

Heräjärvi H (2002) Properties of birch (Betula pendula, B. pubescens) for sawmilling and further processing in Finland. Finland, Finnish Forest Research Institute, Research papers 871. 52 p.

Hill CAS (2006) Wood Modification: Chemical, Thermal and Other Process. John Wiley and Sons Ltd., Chichester.

Hill C (2014) Thermally Modified Wood – the role of hemicelluloses. Final Cost Action FP0904 Conference “Recent Advances in the Field of TH and THM Wood Treatment” May 19-21, 2014, Skellefteå, Sweden.

Hillis SWE (1984) High temperature and chemical effects on wood stability. Wood Sci Technol 18:281-293.

Hinterstoisser B, Weingärtner J, Praznik W. (1992) Influence of wood drying processes on the carbohydrate matrix of wood of Picea Abies. In Proceedings of 3rd IUFRO International Wood Drying Conference, Vienna, Austria, August 18-21, 217-221.

Hirai N, Sobue N , Asano I(1972) Studies on piezoelectric effect of wood IV. Effect of heat treatment on cellulose crystallites and piezoelectric effect of wood. Mokuzai Gakkaishi 18 (6): 535–542.

Gerhards CC, McMillan JM (1976) High-temperature drying effects on mechanical properties of softwood lumber: Proceedings of a research conference; 1976 February 25-26. U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. Madison, WI, USA. 161 pp.

Gindl W, Gupta HS, Grunwald C (2002) Lignification of spruce tracheid secondary cell walls related to longitudinal hardness and modulus of elasticity using nano-indentation. Can J Bot 80(10):1029-1033.

Gindl W, Gupta HS (2002) Cell-wall hardness and Young's modulus of melamine-modified spruce wood by nano-indentation. Comp Part A 33(8):1141-1145.

Gindl W, Gupta HS, Schöberl T, Lichtenegger HC, Fratzl P (2004) Mechanical properties of spruce wood cell walls by nanoindentation. Appl Phys A 79:2069-2073.

Gu H, Young TM, Moschler WW, Bond BH (2004) Potential sources of variation that influence the final moisture content of kiln- dried hardwood lumber. Forest Prod. J. 54(11):65-70.

Imamura Y (1993) Estimation of the fungal resistance of wood composites for structural use. Current Japanese Materials Research 11: 75-84.

Isomäki O, Koponen H, Nummela A, Suomi-Lindberg L(2002) Puutuoteteollisuus 2. Raaka-aineet ja aihiot. [Wood products industries 2. Raw materials and semi-finished products]. Edita Oy, Helsinki. 154 p. (In Finnish).

Jalava M (1945) Strength properties of Finnish pine, spruce, birch and aspen. Communicationes Instituti Forestalis Fenniae 33(3): 1-66. In Finnish with English summary.

Jiang JL, Lu JX (2006) Moisture dependence of the dynamic viscoelastic properties for wood. Journal of Beijing Forestry University 28 (Suppl. 2), Beijing, China, 118–123.

Jiang JL, Lu JX (2008) Dynamic Viscoelasticity of Wood After Various Drying Processes, Drying Technology: An International Journal 26(5): 537-54.

Jiang JL, Lu JX (2009) Dynamic viscoelastic behavior of wood under drying conditions. Front. For. China 4(3): 374–379.

Jiang J, Lu J and Yan H (2008). Dynamic viscoelastic properties of wood treated by three drying methods measured at high-temperature range. Wood Fiber Sci. 40(1): 72-79.

Kanagawa Y, Hayashi K, Yasujima M (1993) Change of dry ability under vacuum drying by improvement of permeability of wood. Vacuum Drying of Wood' 93. High Tatras, Slovakia. 292 pp.

Kelley SS, Rials TG, Glasser WG(1987) Relaxation behaviour of the amorphous components of wood. J. Mater. Sci. 22: 617-624.

Kim G, Jee W, Ra J (1996) Reduction in mechanical properties of Radiata pine wood associated with incipient brown-rot decay. Mokchae Konghak 24 (1): 81-86.

Konnerth J, Eiser M, Jäger A, Bader TK, Hofstetter K, Follrich J, Ters T, Hansmann C, Wimmer R (2010) Macro- and micro-mechanical properties of red oak wood (Quercus rubra L.) treated with hemicellulases. Holzforschung, 64 (4): 447-453.

LeVan SL, Ross RJ, Winandy JE (1990) Effects of fire retardant chemicals on bending properties of wood at elevated temperatures. Res. Pap. FPL-RP-498

Mano F(2002) The viscoelastic properties of cork. Journal of Material Science 37 (2): 257–263.

Mitchell PH, Barnes HM (1986) Effect of drying temperature on the clear wood strength of southern pine treated with CCA-type A. Forest Prod. J. 36(3):8-12.

Mitchell RL, Seborg RM , Millet MA (1953) Effect of heat on the properties and chemical composition of Douglas-fir wood and its major components. Journal of Forest Product Research Society 3:38-42.

Möttönen V(2005) Variation of colour and selected physical and mechanical properties related to artificial drying of sawn silver birch (Betula pendula Roth) timber from plan-tations. Doctoral thesis, Dissertationes Forestales, 43 pp.

Oliver WC, Pharr GM (1992) An improved technique for determining hardness and elasticmodulus using load and displacement sensing indentation experiments. J Mater Res 7(6):1564-1583.

Oloyede A, Groombride P (2000) The influence of microwave heating on the mechanical properties of wood. J. Mater. Process. Technol. 100: 67-73.

Price EW, Koch P (1980) Kiln time and temperature affect shrinkage, warp and mechanical properties of Southern Pine lumber. Forest Prod. J. 30(8): 41-47.

Ressel J B (1999) State of the art for vacuum drying in the wood working industry. Cost Action E15, 13-14 October 1999, Edinburgh, UK.

Schmidt EL, French DW, Gertjejansen R, Herman J, Hall H (1978) Strength reductions in particleboard caused by fungi. Forest Prod. J. 28 (2): 26-31.

Sehlstedt-Persson M (2000) The effect of drying temperature on subsequent moisture and dimensional change for Scots pine and Norway spruce. Holz als Roh- und Werkstoff 58(5):353.

Sik H , Choo K, Zakaria S, Ahmad S, Yusoff M, Chia C(2010) The Influence of drying temperature on the hygroscopicity of rubberwood (Hevea Brasiliensis). Journal of Agricultural Science. 2(1): 48-58.

Sjöeström, E (1981) Wood Chemistry Fundamentals and Applications. Academic Press, New York.

Suchy M, Virtanen J, Kontturi E , Vuorinen T (2010) Impact of Drying on Wood Ultrastructure Observed by Deuterium Exchange and Photoacoustic FT-IR Spectroscopy. Biomacromolecules 11: 2161–2168.

Sugiyama M , Norimoto M (1996) Temperature dependence of dynamic viscoelasticities of chemically treated wood. Mokuzai Gakkaishi 42 (11):1049–1056.

Sugiyama M, Norimoto M(2006) Dielectric relaxation of water adsorbed on chemically treated specimens. Holzforschung 60 (5): 549–557.

Sweet M, Winandy JE (1999) Influence of degree of polymerisation of cellulose and hemicellulose on strength loss in fire-retardant-treated southern pine. Holzforschung 53 (3): 311- 317.

Takamura A (1968) Studies on hot pressing and drying process in the production of fibreboard. III. Softening of fibre components in hot pressing of fibre mat. Mokuzai Gakkaishi, 14: 75–79.

Thiam M, Milota MR, Leichti R(2002) Effect of high-temperature drying on bending and shear strengths of western hemlock lumber. Forest Prod. J. 52(4): 64-68.

Tze WTY, Wang S, Rials TG, Pharr GM, and Kelley SS (2007) Nanoindentation of wood cell walls: Continuous stiffness and hardness measurements.Compos Part A: Appl S 38: 945–953.

Wagenführ R(1996). Holzatlas. [Wood Atlas]. VEB Fachbuchverlag Leipzig. 4th ed. 688 p. (In German).

Welling J (1994) Superheated steam vacuum drying of timber-range of application and advantages. 4th IUFRO International Wood Drying Conference, Rotorua, New Zealand: 460-461.

Whistler RL, Chen CC (1991) Hemicelluloses. In: Lewin, Goldstein (eds) Wood structure and composition. International fiber science and technology series. Vol. 11. Marcel Decker. Imc., New York, NY, USA, 287-320 pp.

Wilcox WW (1978) Review of literature on the effects of early stages of decay on wood strength. Wood and Fiber 9 (4): 252-257.

Wimmer R, Lucas BN, Tsui TY, Oliver WC (1997) Longitudinal hardness and Young's modulus of spruce tracheid secondary walls using nanoindentation technique. Wood Sci Technol 31(2): 31-141.

Winandy, JE, Morrell JJ (1993) Relationship between incipient decay, strength, and chemical composition of Douglas-Fir heartwood. Wood Fiber Sci 25 (3): 278-288.

Winandy, JE (1995) Effects of fire retardant treatments after 18 months of exposure at 150°F (66°C). Res. Note FPL-RN-0264. USDA Forest Serv., Forest Prod. Lab., Madison, WI.UAS.

Winandy JE, Lebow P (2001) Modeling strength loss in wood by chemical composition. Part I. an individual component model for southern pine. Wood Fiber Sci. 33(2): 239-254.

Zhan JF, GU JY, Shi SQ (2009) Rheological Behavior of Larch Timber during Conventional Drying, Drying Technology: An International Journal, 27(10): 1041-1050.

Zhang B., Liu D (2006) Exploring a new developing way of wood drying technology in China. China Forest Prod Ind 33(4): 3-6.






Research Contributions