Analyses of Impregnation Quality and Mechanical Properties of Radiata Pine Wood Treated with Copper Nanoparticle- and Micronized-Copper-Based Wood Preservatives

Abstract

In this work, the impregnation quality and mechanical properties of Pinus radiata D.Don treated with different copper nanoparticles (CuNP) solutions (named K1 and K2) and a commercial preservative (M) were studied. The impregnation quality of radiata pine wood was analyzed by two indicators, penetration and retention. The micro-distribution of preservative in the treated wood was qualitatively evaluated by SEM-EDS, both in the samples containing CuNP and in those treated with the commercial preservative. In addition, some mechanical properties were studied in the preserved wood including MOE, MOR and hardness. The results indicated values by ED XRF retention of 0.96 kg/m3 and 0.86 kg/m3 for K1 and K2, respectively, and 1.01 kg/m3 for M wood impregnated. In the penetration determined by colorimetric test, the wood samples impregnated (with K1, K2 and M) showed 100% penetration. The distribution of CuNP and micronized copper within the wood structure was confirmed by SEM EDS mapping. In mechanical properties, a reduction in MOE was reflected in all wood treated. The control samples were far superior to the K1 and M treated samples and slightly superior to the K2 samples, with no statistically significant differences. On the other hand, samples impregnated with K1 and K2 showed the highest values in hardness parallel and perpendicular to the grain, revealing that these preservative solutions tend to increase hardness. Overall, when it comes to the samples impregnated with micronized copper (M), the mechanical properties were considerably lower compared to the CuNP treated and control wood. Therefore, the CuNP-based preservative did not strongly affect the mechanical properties of the preserved wood.