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European Journal of Wood and Wood Products

, Volume 70, Issue 5, pp 655–665 | Cite as

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

  • Ivana Gavrilović-GrmušaEmail author
  • Manfred Dunky
  • Jovan Miljković
  • Milanka Djiporović-Momčilović
Originals Originalarbeiten

Abstract

The objective of this work was to evaluate the influence of the degree of condensation of urea formaldehyde (UF) resins on the tangential penetration into fir and beech and on the tensile shear bond strength of wood joints.

Tangential penetration was determined by epi-fluorescence microscopy on microtome slides, exposing the bond line on a cross-sectional surface. The higher the degree of condensation (viscosity) of the resins, the lower is the possibility for penetration; beech showed higher penetration than fir.

Bond strengths decreased with increased degree of condensation (viscosity) of the adhesives. Shear strength based on radial penetration was higher than for tangential penetration. The higher the penetration and the thicker, hence, the interphase, the higher was the achieved shear strength.

Keywords

Wood Species Annual Ring Wood Surface Bond Line Tensile Shear 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Abbreviations

UF

Urea-formaldehyde;

AP

Average penetration;

IR

Interphase region;

A

Area of filled lumens and rays;

FIR

Filled interphase region;

CLSM

Confocal laser scanning microscopy;

SEM

Scanning electron microscopy;

DOC

Degree of condensation

Einfluss des Kondensationsgrades von Harnstoff-Formaldehyd-Harzen auf die tangentiale Penetration in Buche und Tanne und auf die Scherfestigkeit von Verklebungen

Zusammenfassung

Ziel der Arbeit war die Erfassung des Einflusses des Kondensationsgrades von Harnstoff-Formaldehyd-Harzen (UF-Harzen) auf die tangentiale Penetration in Tanne und Buche und auf die dabei erzielbaren Zugscherfestigkeiten von Holzverklebungen.

Die tangentiale Penetration wurde mittels EpiFluoreszenzMikroskopie an Mikrotomschnitten erfasst, die die Klebfuge auf einer Querschnittsfläche zeigen. Je höher der Kondensationsgrad, desto geringer ist die Möglichkeit zur Penetration; diese ist in Buche höher als in Kiefer.

Die Scherfestigkeit sinkt mit steigendem Kondensationsgrad (Viskosität) der Bindemittel; die Scherfestigkeit basierend auf radialer Penetration war höher als bei tangentialer Penetration. Je stärker die Penetration und je dicker deshalb die gemeinsame Schicht (Interphase), desto höher waren die erzielten Bindefestigkeiten.

Notes

Acknowledgements

We are grateful indebted to Ing. Petr Pastrnak of DUKOL Ostrava s.r.o., for the preparation of the UF resins used in the investigations reported in this paper.

The research work presented in this paper was financed by the Ministry of Science and Technological Development, Project “Establishment of Wood Plantations Intended for Afforestation of Serbia”–TR 031041

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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Ivana Gavrilović-Grmuša
    • 1
    Email author
  • Manfred Dunky
    • 2
  • Jovan Miljković
    • 1
  • Milanka Djiporović-Momčilović
    • 1
  1. 1.Faculty of ForestryUniversity of BelgradeBelgradeSerbia
  2. 2.Kronospan GmbH LampertswaldeLampertswaldeGermany

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