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Gewählte Master / Diploma Thesis:

Georg Steiner (2014): Zugscherfestigkeit von Fichtenholzverklebungen mit UF- und PUR-Klebstoffen in Abhängigkeit einer thermischen Oberflächenmodifikation.
Master / Diploma Thesis - Institut für Holztechnologie und Nachwachsende Rohstoffe, BOKU-Universität für Bodenkultur, pp 90. UB BOKU obvsg

Data Source: ZID Abstracts
Abstract:
Isocyanat-based polyurethane resins show a good bonding performance because of their characteristic isocyanate group (-N=C=O) which is very reactive. This master thesis tries to analyze the adhesion between a polyurethane resin and a wood surface. Additionally it is also tried to figure out if it’s possible to increase the bonding strength of polyurethane bonds by means of thermal modification of wood surfaces before gluing. Therefore the wood equilibrium moisture content, the contact angle between the resin and the wood surface and the tensile shear strength of samples were tested to validate this assumption. A urea-formaldehyde resin was used to compare the outcomes of the different tests with the ones of the polyurethane adhesive. In general several wood properties are changed by thermal modification. The effect of a significant reduction of equilibrium moisture content after thermal modification was confirmed in this study. On the other hand contact angle measurement enhances with increasing modification intensity (heat and time). The adhesion between wood and resin depends on the adhesive used. The polyurethane resin showed a significant reaction towards thermal modified wood surfaces regarding contact angle changes. By contrast the urea-formaldehyde resin showed increasing contact angles with increasing temperatures. For a final comparison tensile shear samples were produced. The surfaces of these samples were modified with the same modification intensities used for the adhesion and the wood equilibrium moisture content tests. One interesting outcome of the tensile shear test was that a weak thermal surface modification leads to better tensile strength compared to unmodified wooden test samples.

Beurteilende(r): Müller Ulrich

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