New hot-waxing to prevent wood aging

To prevent the degradation of wood surfaces by ultra-violet (UV) radiation and water, modified polyethylene wax and oxidised paraffin composite wax were used for the protection of wood surfaces with hot wax treatment.

The effects of natural beeswax coating and modified synthetic wax coating on wood surface aging behaviour were also studied, says a report in European Coatings.

Results showed that changes in colour, gloss, water uptake, contact angle, micro-morphology, and chemical changes of wood treated with modified synthetic wax hot-waxing were less than those of wood treated with natural beeswax hot-waxing after long-term aging under UV light and water.

Among them, the oxidised paraffin composite wax coating showed the best protective effects on the wood surface, and the composite wax coating reduced the UV penetration and enhanced the UV oxidative degradation resistance.

In addition, the synergistic effect of modified polyethylene wax and oxidised paraffin further reduced the water uptake of wood during the aging process.

According to the researchers, this data shows that the modified synthetic wax and composite wax coating can effectively inhibit the photo-oxidative degradation of wood surface, provide a lasting hydrophobic protection effect on wood, and show long-term photo-stability.

A UV-shielding, hydrophobic and transparent coating has also been developed to improve the weathering resistance properties of wood materials while maintaining the natural aesthetic texture of the wood.

For the novel coating, graphitic carbon nitride nano-sheets (gCNNS) were used as non-toxic and metal-free UV absorber. Cellulose nano-fibril (CNF) was selected as an environment-friendly and renewable film-forming carrier, which addressed the issues of agglomeration and low composite adhesion of gCNNS on the wood surface.

The gCNNS/CNF composite coating was formulated on the wood surface via spin coating method. These coatings can be applied to a wide variety of substrates.

A following hydrophobic treatment by thermal chemical vapour deposition (CVD) method was to solve the problem of rainwater erosion in outdoor application.

After 15-day accelerated weathering tests, the total colour change of the treated sample was 79.6% lower than that of the untreated one. The scientists report that the newly-designed environment-friendly and weathering resistant coatings can be applied to a wide variety of substrates in the future.



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