X-ray photoelectron spectroscopic analysis of CCA treated wood

IRG/WP 92-3700

J N R Ruddick, K Yamamoto, P C Wong, K A R Mitchell

Ponderosa pine and Douglas-fir wood sections were treated with CCA preservative. To elucidate the mechanism of fixation of the CCA, the wood surface was analyzed by X-ray photoelectron spectroscopy (XPS). CCA treatment increased C1 (carbon bonded to carbon and/or hydrogen) and decreased C2 (carbon bonded to one oxygen) in XPS C1s spectra, both in unextracted and pre-extracted sections. This suggested oxidation of hydroxyl groups on cellulose and/or lignin by CCA occurred, followed by the decarboxylation of carbonyl and carboxyl groups. However, the large changes in the state of the carbon atoms recorded during CCA treatment of unectracted wood would appear to be due to migration of extractives to analyzed surfaces as well as to the oxidation of hydroxyl group in wood by CCA. Accelerating fixation produced more C1 than fixation at ambient temperatures. More increase of C1 was related to higher performance against leaching in the accelerating fixation. Surface concentrations of CCA elements determined by XPS was lower in the accelerating fixation than in the usual fixation, which could be one of the causes of lower water repellency on the surface of former section. CCA fixation resulted in a higher water repellent surface, especially in the presence of extractives.


Keywords: ANALYSIS; XPS; CCA; FIXATION; PINUS PONDEROSA; PSEUDOTSUGA MENZIESII; LEACHING; WATER REPELLENCY

Conference: 92-05-10/15 Harrogate, England, UK


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