Original paper(Vol.45 No.4 pp.390)

Dimensional stabilization of wood by glyoxal resin treatments - a few considerations concerning mechanism of dimensional stabilization

Itoh Takafumi; Ishihara Shigehisa

Abstract:For the purpose of enhancing dimensional stabilization of wood, Hinoki (Chamaecyparis obtusa Endl.) sapwood specimens were treated with the mixtures of cyclic methylolurea-formaldehyde compounds, called 'glyoxal resins', and dipropylene glycol (DPG). In this paper, the dimensional stability of the specimens was evaluated, and the mechanism of the dimensional stabilization was discussed. The information obtained was as follows;
(1) Both of the bulking coefficient (B) and antiswelling efficiency (ASE) of the specimens increased with increasing mixing ratio of DPG in mixture. Them maximal ASE endowed by the treatment was more than 70%.
(2) For the specimens treated with the mixtures having constant concentrations, an approximately linear relationship existed between B and ASE, with a high correlation coefficient.
(3) For the specimens treated with the mixtures having a constant ratio of glyoxal resin and DPG, the relationship between weight increase (W.I.) and ASE was similar to the relationship between W.I. and moisture excluding efficiency (MEE). Consequently, it is suggested that the improvement of dimensional stability is also dependent on the decrease of hygroscopicity.
(4) The specimens treated with the dilute mixtures revealed the dimensional stability that was considered to be caused by cross-linking.

Key Words:glyoxal resin, dimensional stability, antiwelling efficiency (ASE), bulking coefficient (B), moisture excluding efficiency (MEE), cross-linking