Properties of wood treated with compound systems of paraffin wax emulsion and copper azole

Wood is a natural and renewable material used extensively. However, it is generally susceptible to biological attacks caused by fungi and termites. Studies showed that copper azole (CA) could effectively inhibit the growth of such organisms. CA belongs to water-borne preservatives and CA-treated wood inevitably suffers from poor dimensional stability. In order to improve the water repellency of CA-treated wood, a paraffin wax emulsion was added to the CA preservative system at different ratios. The compound systems were then used to treat Southern pine (Pinus spp.) samples. The basic properties of the compound systems, such as stability (storage stability and centrifugal stability), particle size and pH value, as well as the weight percent gains, contact angles, water repellency (water absorption, shrinkage and swelling) of treated samples were investigated. The results are as follows: (1) the compound systems of CA and paraffin wax emulsion had a favorable miscibility, and their stabilities all reached level one (good stability); (2) compared with untreated wood, CA-treated samples showed poor water repellency, whereas samples treated with the compound systems indicated an obvious reduction in water absorption, and improved dimensional stability as well.