STUDY ON THE ANTILEACHING PROPERTY OF CHINESE FIR TREATED WITH BORATE MODIFIED BY PHENOL-FORMALDEHYDE RESIN

摘要

In order to investigate the effect of phenol-formaldehyde (PF) resin on the anti-leaching property of disodium octaborate tetrahydrate Na2Bg013.4H20 (DOT), one kind of inorganic borates, PF resins with three viscosities of 200, 1000, and 10000 mPa.s at 20°C which represent low, moderate, and high molecular weights respectively were prepared in laboratory and used in combination with DOT to treat the sapwood of Chinese fir (Cunninghamia lanceolata Hook.). The results showed that higher concentrationof PF could fix boron better. Low molecular weight PF was favourable to improve the leaching resistance of boron because of its capability of penetrating into the wood cell wall. The optimal concentration of DOT was determined as 2 % BAE (boric acid equivalent) compared to 1 % BAE and 3 % BAE used in this study. The increased boron leaching at high concentration of DOT was considered to be caused by the limited capacity of PF to bond boron. SEM analysis showed that great amount of resin is accumulated in cell cavities or on the wood cell wall surface in wood treated with moderate or high molecular weight PF but little resin was found in the cell cavities of wood treated with low molecular weight PF. FITR analysis showed that low molecular weight PF would react with the wood components.