Effect of Particle Size on Wax Distribution in Paraffin Wax Emulsion Impregnated Wood

IRG/WP 17-40779

Wang Wang, Jinzhen Cao, Yiheng Huang

Paraffin wax emulsion impregnation has been a common eco-friendly approach for improving water repellency of wood. In this study, southern pine (Pinus spp.) and Scots pine (Pinus sylvesteris L.) samples were impregnated with paraffin wax emulsions of different solid contents and particle sizes, and then the time domain nuclear magnetic resonance (TD-NMR) was used to elucidate the influence of particle size on wax distribution and penetration in treated wood. The linear relationship between mass and T2 relaxation peak area of the weight of paraffin wax was built, demonstrating a good correlation (R2=0.9808) between wax content determined by TD-NMR and weight percent gain (WPG) determined by gravimetric method, which confirmed that the TD-NMR analysis was an efficient method for reliable determination of wax content in different parts of wax treated wood. According to wax loading and distribution, southern pine samples showed much better permeability than Scots pine samples. With the decrease of particle size, the penetration of wax emulsion increased for both species. The water contact angles on the surface at different depth of wood were also determined, and the result was consistent with the wax distribution investigated by the TD-NMR analysis. The paraffin wax emulsions with small particle size (smaller than 320nm) mentioned in this study were suitable to improve the hydrophobicity of southern pine. However, wax emulsions with further smaller particle size should be developed for Scots pine modification.

Keywords: wood modification, paraffin wax emulsion, particle size, wax distribution, wax penetration, time domain nuclear magnetic resonance, TD-NMR

Conference: 17-06-04/08 Ghent, Belgium

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