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Gewählte Master / Diploma Thesis:

Christian Scheiflinger (2014): Eignung von zellulosemodifiziertem UF für Spanplatten im Feuchtbereich.
Master / Diploma Thesis - Institut für Holztechnologie und Nachwachsende Rohstoffe, BOKU-Universität für Bodenkultur, pp 74. UB BOKU obvsg FullText

Data Source: ZID Abstracts
Abstract:
As a binder in particleboards urea-formaldehyde (UF) resins are predominantly used. The high brittleness and the weak resistance against hydrolysis are limiting factors for the application of UF bonded particleboards under humid conditions. In this study, the attempt was made to improve the toughness of UF resins and enhance the resistance of the glueline against defects caused by swelling and shrinking. For this purpose particleboards, bonded with UF resins mixed with 0, 1, 2 and 3 % of Cellulosenanofibrils (CNF) and Cellulosenanocrystals (CNC) as reinforcement fillers, were produced. One group of the produced particleboards were stressed by storage under humid conditions (95 % relative humidity) and subsequent kiln drying with resulting swelling and shrinking. The results of mechanical testing of the group with humidity pretreatment were compared to the group without treatment. As mechanical tests 24 h thickness swelling, internal bonding and fracture energy were performed. The results neither revealed an improvement of mechanical properties nor a higher resistance against moisture by reinforcing the UF with cellulose. This might have been the result of the unfavorable conditions for the board manufacturing, because many other studies already have revealed the positive effect of the cellulose fiber reinforcement to the mechanical properties of the resin. Probably the high water content of the cellulose reinforced resins led to a hydrolytic degradation already during hotpressing of the boards. The positive reinforcement-influence of the cellulose might be exceeded by the negative effect of the high water content in the particle mat before pressing. Only a direct comparison of specimens with the same water content before pressing (CNF3%, RefW) showed better mechanical properties and an improved moisture resistance of cellulose reinforced specimens in relation to non-reinforced specimens.

Beurteilende(r): Konnerth Johannes
1.Mitwirkender: Veigel Stefan

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