Radiata pine is the main wood species used in the Chilean construction industry, but it must be protected due to its low natural durability. Chemical protection of wood by impregnation allows for a more efficient utilization of the forest resources by extending its useful life. The use of nanoparticles in wood protection has garnered great interest during the last decade, due to their unique physicochemical properties, different from those of larger sized materials. In this research, the impregnation of radiata pine wood with copper nanoparticles (CuNP) was studied in terms of retention, penetration, leaching, and its protective effect against wood rot fungi growth according to EN 113, AWPA A3-91, A9-18, and E11-16. Penetration analysis confirmed a uniform distribution across the wood, with total penetration in the impregnated samples with the highest concentration solution of CuNP. Retention values of the impregnated wood increased proportionally with the concentration of nanoparticles evaluated by EDXRF. Leaching analysis showed copper removal during the first hours of the test, with a constant leaching rate up to 144 h. Impregnated wood mass loss (ML) due to exposure to Gloeophyllum trabeum and Rhodonia placenta fungi were significantly reduced regardless of the CuNP concentration or fungi tested, with an ML smaller than 5% and smaller than 14% for leached samples.

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.