Abstract
The elastic modulus, hardness, and creep factor of wood cell walls in the interphase region of four different adhesive bonds were determined by nanoindentation. In comparison with reference cell walls unaffected by adhesive, interphase cell walls from melamine-urea-formaldehyde (MUF) and phenol-resorcinol-formaldehyde (PRF) adhesive bonds showed improved hardness and reduced creep, as well as improved elastic modulus in the case of MUF. In contrast, cell walls from the interphase region in polyvinylacetate (PVAc) and one-component polyurethane (PUR) bonds showed more creep, but lower elastic modulus and hardness than the reference. Considering the different cell-wall penetration behaviour of the adhesive polymers studied here, it is concluded that damage and loss of elastic modulus to surface cells occurring during the machining of wood is recovered in MUF and PRF bond lines, whereas damage of cell walls persists in PVAc and PUR bond lines.
References
Backman, A.C., Lindberg, K.A.H. (2004) Interaction between wood and polyvinyl acetate glue studied with dynamic mechanical analysis and scanning electron microscopy. J. Appl. Polym. Sci.91:3009–3015.10.1002/app.13507Search in Google Scholar
Bledzki, A.K., Gassan, J. (1999) Composites reinforced with cellulose based fibres. Prog. Polym. Sci.24:221–274.10.1016/S0079-6700(98)00018-5Search in Google Scholar
Bolton, A.J., Dinwoodie, J.M., Davies, D.A. (1988) The validity of the use of SEM/EDAX as a tool for the detection of UF resin penetration into wood cell-walls in particleboard. Wood Sci. Technol.22:345–356.10.1007/BF00353324Search in Google Scholar
Broughton, J.G., Hutchinson, A.R. (2001) Adhesive systems for structural connections in timber. Int. J. Adhes. Adhes.21:177–186.10.1016/S0143-7496(00)00049-XSearch in Google Scholar
Buckley, C.J., Phanopoulos, C., Khaleque, N., Engelen, A., Holwill, M.E.J., Michette, A.G. (2002) Examination of the penetration of polymeric methylene di-phenyl-di-isocyanate (pMDI) into wood structure using chemical-state X-ray microscopy. Holzforschung56:215–222.10.1515/HF.2002.035Search in Google Scholar
CSM Instruments. Overview of mechanical testing standards. Applications Bulletin No. 18, September 2002.Search in Google Scholar
Dunky, M., Niemz, P. Holzwerkstoffe und Leime, Technologie und Einflussfaktoren. Springer-Verlag, Berlin, 2002.10.1007/978-3-642-55938-9Search in Google Scholar
Fan, Z., Swadener, J.G., Rho, J.Y., Roy, M.E., Pharr, G.M. (2002) Anisotropic properties of human tibial cortical bone as measured by nanoindentation. J. Orthopaed. Res.20:806–810.10.1016/S0736-0266(01)00186-3Search in Google Scholar
Fengel, D., Kumar, R.N. (1970) Electron microscopic studies of glued wood joints. Holzforschung24:177–181.10.1515/hfsg.1970.24.6.177Search in Google Scholar
Furuno, T., Goto, T. (1975) Structure of the interphase between wood and synthetic polymer. VII. Mokuzai Gakkaishi21:289–296.Search in Google Scholar
Gao, S.L., Mader, E. (2002) Characterisation of interphase nanoscale property variations in glass fibre reinforced polypropylene and epoxy resin composites. Compos. Sci. Technol.33:559–576.10.1016/S1359-835X(01)00134-8Search in Google Scholar
Gindl, W. (2001) SEM and UV-microscopic investigation of glue lines in Parallam ((R)) PSL. Holz Roh Werkst.59:211–214.10.1007/s001070100194Search in Google Scholar
Gindl, W., Gupta, H.S. (2002) Cell-wall hardness and Young's modulus of melamine-modified spruce wood by nano-indentation. Compos. Sci. Technol.33:1141–1145.10.1016/S1359-835X(02)00080-5Search in Google Scholar
Gindl, W., Schoberl, T. (2004) The significance of the elastic modulus of wood cell walls obtained from nanoindentation measurements. Compos. Sci. Technol.35:1345–1349.10.1016/j.compositesa.2004.04.002Search in Google Scholar
Gindl, W., Dessipri, E., Wimmer, R. (2002) Using UV-microscopy to study diffusion of melamine-urea-formaldehyde resin in cell walls of spruce wood. Holzforschung56:103–107.10.1515/HF.2002.017Search in Google Scholar
Gindl, W., Zargar-Yaghubi, F., Wimmer, R. (2003) Impregnation of softwood cell walls with melamine-formaldehyde resin. Bioresour. Technol.87:325–330.10.1016/S0960-8524(02)00233-XSearch in Google Scholar
Gindl, W., Schoberl, T., Jeronimidis, G. (2004a) The interphase in phenol-formaldehyde and polymeric methylene di-phenyl-di-isocyanate glue lines in wood. Int. J. Adhes. Adhes.24:279–286.10.1016/j.ijadhadh.2003.10.002Search in Google Scholar
Gindl, W., Schoberl, T., Jeronimidis, G. (2004b) Corrigendum to “The interphase in phenol-formaldehyde (PF) and polymeric methylene di-phenyl-di-isocyanate (pMDI) glue lines in wood”. Int. J. Adhes. Adhes.24:535.10.1016/j.ijadhadh.2004.07.001Search in Google Scholar
Gindl, W., Sretenovic, A., Vincenti, A., Muller, U. (2005) Direct measurement of strain distribution along a wood bond line. Part 2: Effects of adhesive penetration on strain distribution. Holzforschung59:307–310.Search in Google Scholar
Gregory, J.R., Spearing, S.M. (2005) Nanoindentation of neat and in situ polymers in polymer-matrix composites. Compos. Sci. Technol.65:595–607.10.1016/j.compscitech.2004.09.001Search in Google Scholar
Kim, J.K., Hodzic, A. (2003) Nanoscale characterisation of thickness and properties of interphase in polymer matrix composites. J. Adhes.79:383–414.10.1080/00218460309585Search in Google Scholar
Kollmann, F.F.P., Côté, W.A.J. Principles of Wood Science and Technology – Solid Wood, 1. Springer, München, 1968.10.1007/978-3-642-87928-9Search in Google Scholar
Konnerth, J., Gindl, W., Mueller, U. (2006a) Elastic properties of adhesive polymers. Part I: Polymer films by means of electronic speckle pattern interferometry. J. Appl. Polym. Sci., in press.10.1002/app.24434Search in Google Scholar
Konnerth, J., Jaeger, A., Eberhardsteiner, J., Mueller, U., Gindl, W. (2006b) Elastic properties of adhesive polymers. Part II: Polymer films and bond lines by means of nanoindentation. J. Appl. Polym. Sci., in press.10.1002/app.24427Search in Google Scholar
Li, F.P., Williams, J.G., Altan, B.S., Miskioglu, I., Whipple, R.L. (2002) Studies of the interphase in epoxy-aluminum joints using nano-indentation and atomic force microscopy. J. Adhes. Sci. Technol.16:935–949.10.1163/156856102760136481Search in Google Scholar
Li, X.D., Bhushan, B. (2002) A review of nanoindentation continuous stiffness measurement technique and its application. Mater. Charact.48:11–36.10.1016/S1044-5803(02)00192-4Search in Google Scholar
Lichtenegger, H.C., Schöberl, T., Bartl, M.H., Waite, H., Stucky, G.D. (2002) High abrasion resistance with sparse mineralization: copper biomaterial in worm jaws. Science289:389–392.10.1126/science.1075433Search in Google Scholar
Oliver, W.C., Pharr, G.M. (1992) An improved technique for determining hardness and elastic-modulus using load and displacement sensing indentation experiments. J. Mater. Res.7:1564–1583.10.1557/JMR.1992.1564Search in Google Scholar
Rapp, A.O., Bestgen, H., Adam, W., Peck, R.D. (1999) Electron energy loss spectroscopy (EELS) for quantification of cell-wall penetration of a melamine resin. Holzforschung53:111–117.10.1515/HF.1999.018Search in Google Scholar
Saiki, H., Goto, T., Sakuno, T. (1975) Scanning electron microscopy of glue lines separated from plywood. Mokuzai Gakkaishi21:283–288.Search in Google Scholar
Sernek, M., Resnik, J., Kamke, F.A. (1999) Penetration of liquid urea-formaldehyde adhesive into beech wood. Wood Fiber Sci.31:41–48.Search in Google Scholar
Singh, A.P., Anderson, C.R., Warnes, J.M., Matsumura, J. (2002) The effect of planing on the microscopic structure of Pinus radiata wood cells in relation to penetration of PVA glue. Holz Roh Werkst.60:333–341.10.1007/s00107-002-0321-1Search in Google Scholar
Spurr, A.R. (1969) A low-viscosity epoxy resin embedding medium for electron microscopy. J. Ultrastruct. Res.26:31–43.10.1016/S0022-5320(69)90033-1Search in Google Scholar
Suchsland, O. (1958) Über das Eindringen des Leimes bei der Holzverleimung und die Bedeutung der Eindringtiefe für die Fugenfestigkeit. Holz Roh Werkst.16:101–108.10.1007/BF02615415Search in Google Scholar
Urena, A., Rams, J., Escalera, M.D., Sanchez, M. (2005) Characterization of interfacial mechanical properties in carbon fiber/aluminium matrix composites by the nanoindentation technique. Compos. Sci. Technol.65:2025–2038.10.1016/j.compscitech.2005.04.013Search in Google Scholar
VanLandingham, M.R., Villarrubia, J.S., Guthrie, W.F., Meyers, G.F. (2001) Nanoindentation of polymers: an overview. Macromol. Symp.167:15–43.10.1002/1521-3900(200103)167:1<15::AID-MASY15>3.0.CO;2-TSearch in Google Scholar
Wimmer, R., Lucas, B.N. (1997) Comparing mechanical properties of secondary cell wall and cell corner middle lamella in spruce wood. IAWA J.18:77–88.10.1163/22941932-90001463Search in Google Scholar
Wimmer, R., Lucas, B.N., Tsui, T.Y., Oliver, W.C. (1997) Longitudinal hardness and Young's modulus of spruce tracheid secondary walls using nanoindentation technique. Wood Sci. Technol.31:131–141.10.1007/BF00705928Search in Google Scholar
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