Bonding Surface Activated Hardwood Flakeboard with Phenol-Formaldehyde Resin

Gardner, Douglas J.; Ostmeyer, Jeffrey G.; Elder, Thomas

doi:10.1515/hfsg.1991.45.3.215

Cited by 15 publications

(6 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Gardner and Elder (1990) found that chemical surface treatments (Gardner et al 1991b) improved modulus of rupture (MOR) and modulus of elasticity (MOE) of the flakeboards, but the same treatment diminished internal bond and dimensional properties of the boards. Chow (1975) concluded that an aqueous borax solution reduced surface inactivation of freshly peeled Douglas-fir, white spruce, and lodgepole pine veneers.…”

Section: Possible Remedies For Surface Inactivationmentioning

confidence: 99%

Comparative analysis of inactivated wood surfaces

Šernek¹,

Kamke²,

Glasser³

2004

Holzforschung

132

View full text Add to dashboard Cite

A wood surface, which is exposed to a high temperature condition, can experience inactivation. Surface inactivation reflects physical and chemical modifications of the wood surface. Consequently, these changes result in reduced ability of an adhesive to properly wet, flow, penetrate, and cure. Thus, an inactivated wood surface does not bond well with adhesives.The changes in surface chemistry, wettability, and adhesion of inactivated wood surfaces, including heartwood of yellow-poplar (Liriodendron tulipifera) and southern pine (Pinus taeda), were studied. Wood samples were dried from the green moisture content condition in a convection oven at five different temperature levels ranging from 50 to 200°C. The comparative characterization of the surface was done by X-ray photoelectron spectroscopy (XPS), sessile drop wettability, and fracture testing of adhesive bonds. Additionally, several chemical treatments were utilized to improve wettability and adhesion of inactivated wood surfaces.The comparative analysis helped elucidate clear relationships between surface chemistry, wettability, and bond performance in regard to surface inactivation. XPS results showed that wood drying caused modification in wood surface chemistry. The oxygen to carbon ratio (O/C) decreased and the C1/C2 ratio increased with drying temperature. The C1 component is related to carbon-carbon or carbon-hydrogen bonds, and the C2 component represents single carbonoxygen bond. A low O/C ratio and a high C1/C2 ratio reflected a high concentration of non-polar wood components (extractives/VOCs) on the wood surface, which modified the wood surface from hydrophilic to more hydrophobic. A hydrophobic wood surface repelled water and wettability of this surface was low (i.e., a high contact angle). Wettability was directly related to the O/C ratio and inversely related to the C1/C2 ratio.iii Contact angle decreased with time and increased with the temperature of exposure. A dependence of wood species was evident. Southern pine had a lower wettability than yellowpoplar, which was due to a greater concentration of non-polar hydrocarbon-type extractives and heat-generated volatiles on the surface. Solvent extraction prior to drying did not improved wettability, whereas, extraction after drying improved wettability. A contribution of extractives migration and pyrolysis products deposition played a significant role in the heat-induced inactivation process of southern pine.The maximum strain energy release rate (G max ) obtained by fracture testing showed that surface inactivation was insignificant for yellow-poplar when exposed to drying temperatures < 187°C. The southern pine was most susceptible to inactivation particularly when bonded with phenol-formaldehyde (PF) adhesive. A typical surface inactivation for southern pine occurred at drying temperatures > 156°C.Chemical treatments improved the wettability of inactivated wood surfaces, but an improvement in adhesion was not evident for specimens bonded with polyvinyl-acetate (PVA) adhesive. Of the chemica...

show abstract

Section: Possible Remedies For Surface Inactivationmentioning

confidence: 99%

Comparative analysis of inactivated wood surfaces

Šernek¹,

Kamke²,

Glasser³

2004

Holzforschung

132

View full text Add to dashboard Cite

show abstract

“…Mechanical pre-treatments such as sanding and planing (Aydin 2004) or densification by rolling (Bekhta et al 2009) and thermo-mechanical densification by pre-pressing (Bekhta 2003; Bekhta and Marutzky 2007; Bekhta et al 2012) can be used to modify the surface characteristics and so improve the glue bonding of wood. To improve bonding ability and wettability and to reactivate wood surfaces for glue wood bonds, some chemical pre-treatments are widely applied to wood surfaces (Belfas et al 1993; Gardner and Elder 1988). Pre-treatment by hydrogen peroxide activates the functional groups on the phenylpropane units of lignin and cellulose so that they can react more effectively and bond with the functional groups more effectively in the phenol-formaldehyde (PF) adhesive (Mirski et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Effect of surface treatment on bondability of birch veneer with PF resin

Bekhta

Sedliacik

2014

International Wood Products Journal

View full text Add to dashboard Cite

The aim of this work was to study the bondability of birch (Betula verrucosa Ehrh.) veneer subjected to different surface treatments (chemical treatment, short term thermo-mechanical densification, and combination of these two processes) using phenol-formaldehyde (PF) resin with the aim of improving bonding during the production of plywood. Four chemical agents (hydrogen peroxide, aluminium potassium sulphate, potassium carbonate, and potassium permanganate) were used for chemical treatment of the veneer surface. The veneer samples were thermo-mechanically densified between heated plates of a laboratory press. The results revealed that short term thermo-mechanical densification and combined chemical and thermomechanical pre-treatment of the veneer surface prior to the resin application reduced the glue spread (a 33% reduction) and improved the bondability of the veneer. The obtained shear strength values for all of the studied treatments exceeded the standard requirements (1?0 MPa), and the properties of the plywood samples satisfied the European standard EN 314-2.

show abstract

“…Hydrogen peroxide was a kind of effective surface activation agent. Surface activation treatment of wood with hydrogen peroxide has been studied by many scholars, for example Lu (2006), Gardner (1988) and Gardner and Elder (1990). Surface activation treatment with hydrogen peroxide was employed in the study reported in this paper.…”

Section: Introductionmentioning

confidence: 99%

Study of improvement of bonding properties of Larch glued laminated timber

Cheng

2010

Pigment &Amp; Resin Technology

View full text Add to dashboard Cite

PurposeThe purpose of this paper is to improve the adhesion of Larch wood, by conducting a study of hydrogen peroxide treatment on Larch wood surfaces.Design/methodology/approachEffect of surface treatment of Larch by H2O2 on the adhesion of Larch wood, as indicated by compression shear strength, was examined in this paper. Surface properties of Larch wood, such as contact angle were evaluated. Shear strength tests for measuring adhesion of Larch blocks were conducted. Fourier transform infrared (FTIR) analysis was employed to examine the chemical functionality of the untreated and treated Larch surface.FindingsIt is found that hydrogen peroxide treatment improved the adhesion of Larch glued laminated timber. The dry compression shear strength of Larch glued laminated timber treated with H2O2 solution is increased by 19.7 per cent compared with the untreated Larch glued laminated timber. FTIR results showed that the intensity of absorption band at 1,730 cm−1 for H2O2 solution‐treated Larch increased as compared with the untreated Larch wood. The results of contact angle showed that wettability of Larch treated with H2O2 solution increased markedly compared with the untreated Larch.Research limitations/implicationsThe improvement of adhesion as a result of hydrogen peroxide treatment mainly applies to radial Larch surface.Practical implicationsThis study provided a simple and practical solution to improving the adhesion of Larch laminated timber glued with water‐based Polymer Isocyanate (WPI) adhesive. Such a hydrogen peroxide surface treatment may be applied to other types of wood.Originality/valueThis method of improving the adhesion of Larch glued laminated timber can be used for other Larch products glued with WPI.

show abstract

Bonding Surface Activated Hardwood Flakeboard with Phenol-Formaldehyde Resin

Cited by 15 publications

References 22 publications

Comparative analysis of inactivated wood surfaces

Comparative analysis of inactivated wood surfaces

Effect of surface treatment on bondability of birch veneer with PF resin

Study of improvement of bonding properties of Larch glued laminated timber

Contact Info

Product

Resources

About