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The wettability and bonding performance of densified VTC beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) bonded with phenol–formaldehyde adhesive and liquefied wood

Benetzbarkeit und Verklebungsverhalten von verdichtetem VTC Buchen- (Fagus sylvatica L.) und Fichtenholz (Picea abies (L.) Karst.), das mit Phenol-Formaldehydharz und Flüssigholz verklebt wurde

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An Erratum to this article was published on 21 February 2013

Abstract

The influence of viscoelastic thermal compression (VTC) on surface wettability and bonding performance of wood was evaluated. Low quality beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) were densified with the VTC process to different degrees of densification. Control and densified strips were bonded with phenol–formaldehyde (PF) adhesive and liquefied wood (LW). Shear strength of bonded assemblies was determined after 1 week of conditioning at 20 °C and relative humidity of 65 %. Wettability was determined on the basis of the contact angle of water, PF adhesive, and LW using the Wilhelmy method. Results showed that densification of beech and spruce wood did not significantly affect the shear strength of specimens bonded with PF adhesive. In beech assemblies bonded with LW shear strength decreased significantly with increased density, whereas in bonded spruce specimens decrease of shear strength was not significant. It was found that degree of densification and bonding process used in the study were not appropriately chosen for spruce wood specimens, since major deformations after the bonding process occurred. Wettability changed significantly after densification. Contact angle of water and LW increased after densification, whereas contact angle of PF showed inverse trend and decreased after VTC process. Furthermore, the degree of densification had a minor effect on the wettability.

Zusammenfassung

Der Einfluss einer viskoelastischen thermischen Verdichtung (VTC) auf die Oberflächenbenetzbarkeit und das Verklebungsverhalten wurde untersucht. Buchen- (Fagus sylvatica L.) und Fichtenholz (Picea abies (L.) Karst.) geringer Qualität wurden mit viskoelastischer thermischer Verdichtung verschieden stark verdichtet. Kontroll- und verdichtete Proben wurden mit Phenol-Formaldehyd-(PF)-Harz und Flüssigholz (LW) verklebt. Die Scherfestigkeit der verklebten Prüfkörper wurde nach einwöchiger Konditionierung bei 20 °C und 65 % relativer Feuchte bestimmt. Die Benetzbarkeit wurde anhand des Kontaktwinkels von Wasser, PF-Harz und Flüssigholz mit Hilfe der Wilhelmy-Methode bestimmt. Die Ergebnisse zeigten, dass die Verdichtung von Buchen- und Fichtenholz keinen signifikanten Einfluss auf die Scherfestigkeit der mit PF-Harz verklebten Prüfkörper hatte. Bei den mit Flüssigholz verklebten Buchenprüfkörpern nahm die Scherfestigkeit mit zunehmender Dichte signifikant ab, wohingegen der Rückgang der Scherfestigkeit in verklebten Fichtenprüfkörpern nicht signifikant war. Es zeigte sich, dass die in dieser Studie verwendeten Verdichtungsgrade und Verklebungsverfahren für die Prüfkörper aus Fichtenholz nicht geeignet sind, da nach dem Verkleben starke Verformungen auftraten. Die Benetzbarkeit war nach der Verdichtung signifikant verändert. Der Kontaktwinkel von Wasser und Flüssigholz nahm nach der Verdichtung zu, wohingegen der Kontaktwinkel von PF-Harz einen gegenteiligen Trend aufwies und nach der VTC-Behandlung abnahm. Darüber hinaus hatte der Verdichtungsgrad einen geringen Einfluss auf die Benetzbarkeit.

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Acknowledgments

The authors gratefully acknowledge the financial support by the Slovenian Research Agency through the fundamental research project J4-2177 “Development of environmentally friendly adhesives from renewable plant polymers” and bilateral project BI-US/11-12-041 “Adhesive bonding of viscoelastic thermal compressed wood with environmentally friendly adhesives”.

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Authors and Affiliations

  1. Department of Wood Science and Technology, Biotechnical Faculty, University of Ljubljana, Rožna dolina, C. VIII/34, 1000, Ljubljana, Slovenia

    Ugovšek Aleš, Milan Sernek & Matjaž Pavlič

  2. Department of Wood Science and Engineering, Oregon State University, 119 Richardson Hall, Corvallis, OR, USA

    Frederick A. Kamke

  3. Andrej Marušič Institute, University of Primorska, Muzejski trg 2, 6000, Koper, Slovenia

    Andreja Kutnar

  4. ILTRA d.o.o., Celovška cesta 268, 1000, Ljubljana, Slovenia

    Andreja Kutnar

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  1. Ugovšek Aleš
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  2. Frederick A. Kamke
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  3. Milan Sernek
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  4. Matjaž Pavlič
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  5. Andreja Kutnar
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Correspondence to Andreja Kutnar.

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Aleš, U., Kamke, F.A., Sernek, M. et al. The wettability and bonding performance of densified VTC beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) bonded with phenol–formaldehyde adhesive and liquefied wood. Eur. J. Wood Prod. 71, 371–379 (2013). https://doi.org/10.1007/s00107-013-0669-4

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  • DOI: https://doi.org/10.1007/s00107-013-0669-4

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