Source: Aalto UniversitySource: Aalto UniversityIn a bid to reduce the environmental impact of the textile industry, researchers at Aalto University in Finland have created a sustainable wax coating for making textiles water repellant.

To produce the coating, researchers used carnauba wax, an ingredient commonly found in medicine and food, in addition to being applied as a surface coating to certain fruits and car waxes.

To create the coating for textiles, carnauba wax is thawed and decomposed in water into negatively charged wax particles like cellulose. To adhere the wax particles to a cellulose surface, a positively charged ingredient is necessary to behave as a buffer as oppositely charged particles tend to attract each other. As such, polylysine, which is a natural protein, is typically employed. Yet, polylysine is extremely expensive, so the Aalto team opted instead to use a positively charged starch already on the market. Although reportedly not as effective as polylysine, two layers of the starch combined with the two wax particles work to make the waterproof coating for textiles.

A challenge plaguing the textile industry in terms of waterproofing fabric in particular is that waterproofing solutions tend to introduce toxic chemicals into the process. However, according to the Aalto team, what sets it's solution apart from other waterproofing solutions is that in addition to being nontoxic, their version is also breathable.

To test the treated textile’s breathability, researchers measured the breathability of the textiles treated with the wax coating against the textiles treated with commercial coatings. The team determined that the wax coating not only made the textile waterproof, but also enabled the textiles to retain their breathability.

Also during testing, the researchers determined that the wax coating was not resistant to washing with a detergent. As such, the team concluded that the coating is better suited for outerwear, like coats, that do not need to be washed as frequently as other textiles. Likewise, the team agreed that the ideal level of water resistance was achieved when the treated garment was dried at a temperature lower than the melting temperature of wax.

Additionally, the team tested the coating on different materials, including tencel, cotton, viscose, cotton knitwear and hemp, and discovered that the surface roughness of the textiles affected how well the coating repelled water. For instance, the rougher the surface, the better it repelled, according to the team. The researchers concluded this was due to the water droplets on a rough surface contact the surface of the textile in a smaller area, according to Aalto University Ph.D. student Nina Forsman.

The research appears in the journal Carbohydrate Polymers.

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