When sustainability is a growing concern within the textile and clothing industry as the industry uses a quarter of all the chemicals produced across the globe, scientists from Aalto University used an ecological method to make garments water-resistant with wax obtained from Brazilian palm tree leaves.
The treatment is non-toxic and doesn’t impair breathability.
Whenever to apply the functionality in water-resistance, there has a combination of high surface roughness and low surface energy.
In this combined application, the fluorocarbons tend to be used as their organic characteristics can imply the rules to decrease the surface energy.
But their high persistency causes long term problem and provide poor bio-degradability when they are thrown as waste. As also, covalent binding or adsorption of inorganic materials furthermore aﬀect the biodegradability of cellulose, contributing to textile waste.
Aalto researchers have developed an ecological and water repellent wax particle coating suitable for wood cellulose fibers, which also retains the breathability and natural feel of the textile.
The coating uses carnauba wax, which is also used in such things as medicines, foodstuffs, as well as the surface treatment of fruits and car waxes. The new coating is suitable not only for textiles but also for other cellulose-based materials.
“We tested the coating on different textile materials: viscose, Tencel, cotton, hemp and cotton knitwear. We found that the surface roughness of textiles affects how well it repels water – the rougher the surface, the better.”
To do this, the team thawed the wax, which was allowed to decompose in water, then producing anionic particles similar to cellulose fibers. Having the same charge, the anionic particles will not be able to bind with cellulose, so a cationic buffer like polylysine was ideal for this study since it is a natural protein.
With the difference in properties between the polylysine and the cationic starch, the researchers used a mixture of two layers of starch and two wax particles, enough to make the garment effectively waterproof.
The team found that the wax coating is not resistant to detergent washing, so the product is best suited for less frequently washed outer garments such as jackets.
For the sake of simplicity of use, the consumer could potentially apply the coating themselves to the textile after each wash, and this requires more research and development though.
The effect of the drying temperature after wax treatment on waterproofing was also observed, and it was concluded that the best water resistance is obtained when the drying temperature is lower than the melting temperature of the wax.
“We tested the coating on different textile materials: viscose, Tencel, cotton, hemp and cotton knitwear. We found that the surface roughness of textiles affects how well it repels water – the rougher the surface, the better,” explained by Aalto University Ph.D. student Nina Forsman about how the roughness of the garment also affects the efficiency of the product.
“This is because, on a rough surface, water droplets contact the textile surface in a smaller area,” Nina added.
In the experiment it was found that a curing temperature of 70°C gave the highest WCA, and curing temperature of 60°C or higher gave good long-term water-repellency. So they have shown that, the wax can be used as in surface free energy and combine the roughness to make water repellent function in fabric.