Bio-based coating for wood outperforms traditional synthetic options
Researchers turn a non-toxic residue into wood coating that resists
abrasion, stain, and sunlight

Date:
July 23, 2021
Source:
Aalto University
Summary:
Researchers have used lignin, a natural polymer abundant in wood and
other plant sources, to create a safe, low-cost and high-performing
coating for use in construction. As there is a global urge to
meet the rising sustainability standards, this new coating has
great potential to protect wood, whose use in construction is
continually increasing. The new coating is non-toxic, hydrofobic,
it retains wood's breathability and natural roughness while being
resistant to color changes and abrasion.



FULL STORY ==========================================================================
Due to the global efforts to meet sustainability standards, many countries
are currently looking to replace concrete with wood in buildings. France,
for example, will require that all new public buildings will be made from
at least 50 percent wood or other sustainable materials starting in 2022.


========================================================================== Because wood is prone to degradation when exposed to sunlight
and moisture, protective coatings can help bring wood into wider
use. Researchers at Aalto University have used lignin, a natural polymer abundant in wood and other plant sources, to create a safe, low-cost
and high-performing coating for use in construction.

'Our new coating has great potential to protect wood. It's more water
repellent than a lot of commercial coatings because it retains the natural structure of wood and its micro-scaled roughness. Since it's hydrophobic,
the coating is also quite resistant to stains, while lignin's inherent structure resists colour changes from sunlight. It also does an excellent
job of retaining wood's breathability,' explains Alexander Henn, doctoral candidate at Aalto University, The School of Chemical Engineering.

Lignin is often regarded as a waste product of pulping and biorefinery processes. Each year, about 60-120 million tonnes of lignin is isolated worldwide, of which 98 percent is incinerated for energy recovery. Lignin
has several beneficial properties; however, the poor solubility of most
lignin types and the mediocre performance of lignin-based products have
so far limited its commercial applications.

'Lignin as a coating material is actually very promising with its many
benefits compared to the synthetic and bio-based coatings currently
used. It has excellent anti-corrosion, anti-bacterial, anti-icing,
and UV-shielding properties. Our future research will concentrate on
developing characteristics like elasticity of the coating', says Monika O"sterberg, Head of the Department of Bioproducts and Biosystems at
Aalto University.

Currently, widely used mechanically protective coatings for materials
such as wood, concrete, metals, and composites are petroleum-based, which include substances that are harmful for the environment. Vegetable-oil
coatings -- like those made from tall, linseed, coconut, soybean,
and castor -- can be more sustainable alternatives but they often lack durability. As a result, these oils are often combined with synthetic
materials to improve their performance.

More sustainable and non-toxic alternatives can help the coating industry
meet new safety regulations. For example, the amount of volatile organic compounds (VOCs) has been regulated not only due to their impact on
health but also on the ozone layer. Similarly, the European Union (EU)
has placed restrictions on some chemicals used by the coating industry,
such as bisphenol A and formaldehyde (used in epoxy and polyurethane
coatings), and recently classified titanium dioxide -- one of the most
widely used pigments in paints -- as a class II carcinogen.

========================================================================== Story Source: Materials provided by Aalto_University. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Karl Alexander Henn, Nina Forsman, Tao Zou, Monika
O"sterberg. Colloidal
Lignin Particles and Epoxies for Bio-Based, Durable, and
Multiresistant Nanostructured Coatings. ACS Applied Materials &
Interfaces, 2021; DOI: 10.1021/acsami.1c06087 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/07/210723105310.htm

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