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Microstructure and Quantitative Micromechanical Analysis of Wood Cell–Emulsion Polymer Isocyanate and Urea–Formaldehyde Interphases

Part of: Micrographia Collection

Published online by Cambridge University Press:  15 March 2017

Lizhe Qin ,
Lanying Lin ,
Feng Fu  and
Mizi Fan
Lizhe Qin
Affiliation:
Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China
Lanying Lin*
Affiliation:
Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China College of Engineering, Design and Physical Sciences, Brunel University, Middlesex UB8 3PH, UK
Feng Fu
Affiliation:
Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China
Mizi Fan*
Affiliation:
College of Engineering, Design and Physical Sciences, Brunel University, Middlesex UB8 3PH, UK
*
*Corresponding authors. linly@caf.ac.cn; Mizi.Fan@brunel.ac.uk
*Corresponding authors. linly@caf.ac.cn; Mizi.Fan@brunel.ac.uk
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Abstract

Emulsion polymer isocyanate (EPI) and urea-formaldehyde (UF) were selected as typical resin systems to investigate the microstructure of wood–adhesive interphases by fluorescence microscopy (FM) and confocal laser scanning microscopy (CLSM). Further, a quantitative micromechanical analysis of the interphases was conducted using nanoindentation. The FM results showed that the UF resin could penetrate the wood to a greater extent than the EPI resin, and that the average penetration depth for these two resin systems was higher in the case of latewood. CLSM allowed visualization of the resin distribution with contrasting colors, showing that the EPI resin could not penetrate the cell wall, whereas UF resin could enter the cell walls. The micromechanical properties of the cell walls were almost unaffected by EPI penetration but were significantly affected by UF penetration, especially in the first cell wall from the glueline. This further confirmed that only cell walls with resin penetration can improve the mechanical properties of the interphase regions.

Keywords

interphase microstructuremicromechanical propertiesfluorescence microscopeconfocal laser scanning microscopenanoindentation
Type
Micrographia
Information
Microscopy and Microanalysis , Volume 23 , Issue 3 , June 2017 , pp. 687 - 695
Copyright
© Microscopy Society of America 2017 

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References

Bolton, A., Dinwoodie, J. & Davies, D. (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.CrossRefGoogle Scholar
Buckley, C., Phanopoulos, C., Khaleque, N., Engelen, A., Holwill, M. & Michette, A. (2002). Examination of the penetration of polymeric methylene di-phenyl-di-isocyanate (pMDI) into wood structure using chemical-state X-ray microscopy. Holzforschung 56, 215–222.Google Scholar
Frazier, C.E. & Ni, J. (1998). On the occurrence of network interpenetration in the wood-isocyanate adhesive interphase. Int J Adhes Adhes 18, 81–87.CrossRefGoogle Scholar
Gavrilović-Grmuša, I., Dunky, M., Miljković, J. & Djiporović-Momčilović, M. (2012 a). Influence of the degree of condensation of urea-formaldehyde adhesives on the tangential penetration into beech and fir and on the shear strength of the adhesive joints. Eur J Wood Wood Prod 70, 655–665.Google Scholar
Gavrilović-Grmuša, I., Dunky, M., Miljković, J. & Djiporović-Momčilović, M. (2012 b). Influence of the viscosity of UF resins on the radial and tangential penetration into poplar wood and on the shear strength of adhesive joints. Holzforschung 66, 849–856.CrossRefGoogle Scholar
Gibson, L.J. & Ashby, M.F. (2001). Cellular Solids: Structure and Properties. Cambridge: Cambridge University Press.Google Scholar
Gindl, W. (2001). SEM and UV-microscopic investigation of glue lines in Parallam® PSL. Eur J Wood Wood Prod 59, 211–214.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. Holzforschung 56, 103–107.Google Scholar
Gindl, W. & Gupta, H. (2002). Cell-wall hardness and Young’s modulus of melamine-modified spruce wood by nano-indentation. Compos Part A Appl S 33, 1141–1145.CrossRefGoogle Scholar
Gindl, W., Gupta, H., Schöberl, T., Lichtenegger, H.C. & Fratzl, P. (2004 a). Mechanical properties of spruce wood cell walls by nanoindentation. Appl Phys A Mater 79, 2069–2073.Google Scholar
Gindl, W., Schöberl, T. & Jeronimidis, G. (2004 b). The interphase in phenol–formaldehyde and polymeric methylene di-phenyl-di-isocyanate glue lines in wood. Int J Adhes Adhes 24, 279–286.CrossRefGoogle 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. Holzforschung 59, 307–310.Google Scholar
Hancock, W.V. & Northcott, P.L. (1961). Microscopic identification of undercured glue bonds in plywood. Forest Prod J 11, 316–319.Google Scholar
Hare, D. & Kutscha, N. (1974). Microscopy of eastern spruce plywood gluelines. Wood Sci 6, 294–304.Google Scholar
Johnson, S.E. & Kamke, F.A. (1992). Quantitative analysis of gross adhesive penetration in wood using fluorescence microscopy. J Adhes 40, 47–61.Google Scholar
Kamke, F.A. & Lee, J.N. (2007). Adhesive penetration in wood-a review. Wood Fiber Sci 39, 205–220.Google Scholar
Kamke, F.A., Nairn, J.A., Muszynski, L., Paris, J.L., Schwarzkopf, M. & Xiao, X. (2014). Methodology for micromechanical analysis of wood adhesive bonds using X-ray computed tomography and numerical modeling. Wood Fiber Sci 46, 15–28.Google Scholar
Konnerth, J., Gierlinger, N., Keckes, J. & Gindl, W. (2009). Actual versus apparent within cell wall variability of nanoindentation results from wood cell walls related to cellulose microfibril angle. J Mater Sci 44, 4399–4406.CrossRefGoogle ScholarPubMed
Konnerth, J. & Gindl, W. (2006). Mechanical characterisation of wood-adhesive interphase cell walls by nanoindentation. Holzforschung 60, 429–433.Google Scholar
Konnerth, J., Harper, D., Lee, S.H., Rials, T.G. & Gindl, W. (2008). Adhesive penetration of wood cell walls investigated by scanning thermal microscopy (SThM). Holzforschung 62, 91–98.Google Scholar
Liang, K., Du, G.B., Hosseinaei, O., Wang, S.Q. & Wang, H. (2011). Mechanical properties of secondary wall and compound corner middle lamella near the phenol-formaldehyde (PF) adhesive bond line measured by nanoindentation. Adv Mater Res 236, 1746–1751.CrossRefGoogle Scholar
Marcinko, J.J., Devathala, S., Rinaldi, P.L. & Shanci, B. (1998). Investigating the molecular and bulk dynamics of PMDI/wood and UF/wood composites. Forest Prod J 48, 81–84.Google Scholar
Marra, A.A. (1992). Technology of Wood Bonding: Principles in Practice. New York: Van Nostrand Reinhold.Google Scholar
Mckinley, P., Kamke, F.A., Ching, D.J., Zauner, M. & Xiao, X. (2016). Micro X-ray computed tomography of adhesive bonds in wood. Wood Fiber Sci 48, 2–16.Google Scholar
Nuryawan, A., Park, B.D. & Singh, A.P. (2014). Penetration of urea–formaldehyde resins with different formaldehyde/urea mole ratios into softwood tissues. Wood Sci Technol 48, 889–902.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.CrossRefGoogle Scholar
Rapp, A., Bestgen, H., Adam, W. & Peek, R.D. (1999). Electron energy loss spectroscopy (EELS) for quantification of cell-wall penetration of a melamine resin. Holzforschung 53, 111–117.CrossRefGoogle Scholar
Sernek, M., Resnik, J. & Kamke, F.A. (1999). Penetration of liquid urea-formaldehyde adhesive into beech wood. Wood Fiber Sci 31, 41–48.Google Scholar
Smith, M.J., Dai, H. & Ramani, K. (2002). Wood-thermoplastic adhesive interface-method of characterization and results. Int J Adhes Adhes 22, 197–204.Google Scholar
Stöckel, F., Konnerth, J., Kantner, W., Moser, J. & Gindl, W. (2010). Tensile shear strength of UF- and MUF-bonded veneer related to data of adhesives and cell walls measured by nanoindentation. Holzforschung 64, 337–342.Google Scholar
Stöckel, F., Konnerth, J., Moser, J., Kantner, W. & Gindl-Altmutter, W. (2012). Micromechanical properties of the interphase in pMDI and UF bond lines. Wood Sci Technol 46, 611–620.Google Scholar
Tarkow, H., Feist, W.C. & Southerland, C.F. (1966). Interaction of wood with polymeric materials. Penetration versus molecular size. Forest Prod J 16, 61–65.Google Scholar
Tze, W.T.Y., Wang, S., Rials, T.G., Pharr, G.M. & Kelley, S.S. (2007). Nanoindentation of wood cell walls: Continuous stiffness and hardness measurements. Compos Part A Appl S 38, 945–953.Google Scholar
White, M.S. (1977). Influence of resin penetration on the fracture toughness of wood adhesive bonds. Wood Sci 10, 6–14.Google Scholar
Wimmer, R., Lucas, B., Oliver, W. & Tsui, T. (1997). Longitudinal hardness and Young’s modulus of spruce tracheid secondary walls using nanoindentation technique. Wood Sci Technol 31, 131–141.Google Scholar
Xing, C., Riedl, B., Cloutier, A. & Shaler, S.M. (2005). Characterization of urea–formaldehyde resin penetration into medium density fiberboard fibers. Wood Sci Technol 39, 374–384.Google Scholar
Zhang, Y., Liu, C., Wang, S., Wu, Y., Meng, Y., Cui, J., Zhou, Z. & Ma, L. (2015). The influence of nanocellulose and silicon dioxide on the mechanical properties of the cell wall with relation to the bond interface between wood and urea-formaldehyde resin. Wood Fiber Sci 47, 1–9.Google Scholar