To cite this version:Radoslaw Mirski, Dorota Dziurka, Janina Łęcka. Potential of shortening pressing time or reducing pressing temperature for plywood resinated with PF resin modified using alcohols and esters. European Journal of Wood and Wood Products, Springer Verlag, 2010, 69 (2) Abstract:The study was an analysis of the potential to shorten pressing time or reduce pressing temperature for plywood resinated with alcohol-and ester-modified PF resin. Birch and pine plywoods were produced using such modified resin at a temperature range of 135 to 115°C, at a constant pressing time (4 min) and at pressing times ranging from 240 to 150 s at a constant pressing temperature (135°C). Tests showed that the application of PF resin modified with polyols and esters makes it possible, under standard pressing conditions, i.e.135°C and pressing time of 4 min, to produce plywood with improved properties in comparison to respective control plywoods. Moreover, it was shown that the used modifiers enhance resin reactivity, facilitating an adequate course of resin curing, resulting in the manufacture of plywoods with good properties even at a pressing temperature reduced by 20°C or pressing time shortened to 150 s. Potential von mit Alkohol und Estern modifiziertem PF-Harz zur Reduzierung der Presszeit oder der Presstemperatur bei der Sperrholzherstellung ZusammenfassungIn dieser Studie wurde untersucht, wie die Presszeit bzw.

Properties of liquid and cured phenolformaldehyde (PF) resin modified with esters were analyzed in this study. Esters with different carbon chain lengths, both in the acid and alcohol groups, were applied in the experiments. It was found that the modification of phenolic resin with applied esters does not deteriorate its pot life at the temperature of 208C. It results in an increase of its reactivity at higher temperatures, manifested in the shortening of gel time at 1308C and a decrease of activation energy. Results of FTIR tests of polycondensed modified PF resin showed that products of alkali hydrolysis of esters not only catalyze the curing reaction of resin, but also become embedded in its structure.

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ABSTRACT:The purpose of the research was to study the influence of H 2 O 2 on the properties of fluid phenolic (PF) resin, the curing process, the cured resin structure, and the properties of the particleboards produced with its use. The influence of added H 2 O 2 on resin usability at 20°C, on the gel time of the modified PF resin in the temperature range 110 -140°C, and on the activation energy of the curing process were studied. Also, the structure of the cured resin was examined by Fourier transform infrared spectroscopy. Finally, the properties of the obtained particleboards were determined. The results indicate that the H 2 O 2 modification leads to greater reactivity of the phenolic resin and increases the mechanical properties of particleboards. In contrast, there is no significant influence of H 2 O 2 on the water resistance of the particleboards.

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