University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal

Logo BOKU Resarch Portal

Gewählte Doctoral Thesis:

Frank Stöckel (2013): MIKROMECHANIK UND STRUKTUR VON HOLZWERKSTOFFEN.
Doctoral Thesis - Institut für Holzforschung (IHF), BOKU-Universität für Bodenkultur, pp 99. UB BOKU obvsg

Data Source: ZID Abstracts
Abstract:
The bandwidth of physical properties of wood adhesives is wide. Within the range of such adhesives, one finds great differences of penetration behavior in the wood substrate and mechanical characteristics. The present work focuses on the properties of adhesives and wood cell-walls within interphase regions of wood adhesive bonds; while the influences of type of adhesive and conditions during and after cure were of special interest. Adhesives used in the wood-based panels industry as well as for structural applications were mechanically characterized in the cured state. Wood cell-wall penetration and its mechanical effect on interphase cell-walls was studied. Investigations were performed at a macroscopic and microscopic level in order to find correlations between properties on the cell-wall level and macro-mechanical bond performance. For amino resins, phenolic and pMDI (polymeric methylene diphenyl diisocyanate) resins it was shown they penetrate and more importantly embrittle wood cell-walls in bond line regions; while the level of embrittlement as well as adhesive stiffness decreases in this respective order. Testing showed that these properties depend on ambient conditions during and after curing, i.e. short term influences such as water contact typically causes softening of adhesives. In this context high variability was generally observed for phenolic resins (up to 98% decrease in hardness) - while for amino resins for panel production showed lower sensitivity (<30% hardness decrease). From these relationships and others between mechanical bond line behavior and variations of curing and storing conditions observed in this study, a better understanding of the underlying principles of bond performance and durability could be achieved. Thus, the findings contribute to the design of advanced adhesives with optimized mechanical properties for increasing efficiency, performance, and environmental friendliness in wood industry usage.

Betreuer: Gindl-Altmutter Wolfgang
1. Berater: Müller Ulrich
2. Berater:

© BOKU Wien Imprint