Enhanced Weathering Resistance of Radiata Pine Wood by Treatment with an Aqueous Styrene/Acrylic Acid Copolymer Dispersion

Abstract

Radiata pine (Pinus radiata Don.) sapwood was treated with an aqueous dispersion solution of styrene/acrylic acid (St/AA) copolymer (5, 15, or 25%) and the treatment effect on weathering of wood was determined. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggested that the St/AA treatment delayed lignin degradation during artificial weathering; the protection effect increased with St/AA concentration. Decrease in water contact angle upon weathering for the treated wood was also slower than for the untreated control. Scanning electron microscopy revealed that the St/AA polymer filled some wood cell lumina, which facilitates to inhibit moisture and light (especially ultraviolet light) penetration into wood. During 12 months of outdoor exposure, the St/AA-treated wood boards had lower moisture content and less detachment of earlywood cells than the untreated controls. Treatments with St/AA stabilized the surface color by inhibiting photo-oxidation of cell wall polymers and propagation of staining fungi. The results suggest that treatment with St/AA can substantially improve wood’s resistance to weathering.

Keywords:

• Wood
• chemical modification
• styrene/acrylic copolymer
• weathering
• lignin photodegradation

ACKNOWLEDGMENTS

The authors thank Yanhua Zhang at Northeast Forestry University for her help with XPS measurements.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.

FUNDING

This work was financed by the National Natural Science Foundation of China (31890772).