Tanalith E 3494 impregnated wood: Characterisation and thermal behaviour

Nowadays Tanalith® E 3494 (which is a copper azole based preservative) is the most widely used alternative wood preservative across Europe. In the present paper Tanalith® E 3494 impregnated wood is characterised through Fourier transform infrared spectroscopy (FTIR), revealing that carboxylic groups, phenolic groups and aromatic esters are the most active binding sites of copper during impregnation. Furthermore, the thermal behaviour of the Tanalith® E 3494 solution, the impregnated wood and untreated wood is studied by thermogravimetric (TG) analysis. The solution decomposes according to a four-step decomposition process, mainly in the temperature range below 400 °°C, resulting in the black residue CuO. The thermal behaviour of Tanalith® E 3494 impregnated wood differs from that of untreated wood in terms of a higher charcoal yield, a clear shoulder in the DTG curve and a narrower DTG peak. The volatile compounds released during TG analysis are measured by mass spectrometry (MS), resulting in almost the same MS spectra for the untreated and treated wood samples, but a different decomposition profile for the Tanalith® E 3494 solution. Release of volatile copper compounds is not observed during heating (in inert atmosphere) of the Tanalith® E 3494 solution, nor during heating of the impregnated wood.