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Gewählte Doctoral Thesis:

Stefan Bockel (2020): Structural bonding of European beech wood (Fagus sylvatica L.) with polyurethane adhesives - A study investigating various aspects of wood-adhesive interactions with a focus on wood extractives.
Doctoral Thesis - Institut für Holztechnologie und Nachwachsende Rohstoffe, BOKU-Universität für Bodenkultur, pp 139. UB BOKU obvsg FullText

Data Source: ZID Abstracts

Abstract:: This study was performed on the base of an industrial research project that was mainly concerned to the development of a two-component polyurethane adhesive (2C PUR) system as an alternative for structural hardwood bonding. An experimental 2C PUR system was characterized and adjusted by various additives and fillers towards a proper hardwood bonding. This approach showed a certain capability of 2C PUR for structural hardwood bonding and sufficient performance in dry conditions, while the system still shows room for improvement in wet conditions. In order to develop an adhesive system for structural hardwood bonding, deeper understanding of the interactions at the wood-adhesive interface and interphase are required. Therefore, main focus of this thesis was to better understand the possible influence of wood extractives and the performance of the interface at varying climate conditions. In the focus of the present research were polyurethane adhesives, but melamine-urea-formaldehyde and phenol-resorcinol-formaldehyde adhesives were also tested for comparison. Main part of the investigation dealt with the influence of wood extractives on the curing behavior and mechanical performance on wood bonds in varying climate conditions. The findings show that all tested adhesive systems were negatively influenced by specific wood extractives. However, the adhesives were mainly influenced by those extractives which commonly occur in both, soft- and hardwoods. In addition, the influence of an adhesion promoting agent (primer) in combination with 1C PUR on the performance of beech wood bonds was tested. As a novelty, nanoindentation was successfully used to characterize the wood-adhesive interactions at the interface of water-stored bonds and extend possible application of this method. However, only minor effects of the primer on the local adhesion between adhesive and cell wall could be observed.; Betreuer: Konnerth Johannes; 1. Berater: