Brussels (Brussels Morning) Masks currently in use for personal protection are mostly made of disposable fibre cloth.Woven fabric masks, which were in medical use until the 1970s, can offer, so the experts say, a “better than nothing” alternative. Some countries, such as Germany, now require filtering masks to be worn in public indoor spaces. Belgium still allows the use of cloth masks, but requires everyone to wear them when outdoors in busy areas in the cities. Most single-use face masks are produced from polypropene, a plastic-based material because of its filtering capacity and it ability to retain a static charge and resist fluids.
”Of course we should control the use of these single-use plastic products,” sighs Ali Harlin, a research professor with the Finnish Technical Research centre, who studies sustainability of biomass.
In the wake of the pandemic, the environmental impact of the billions of masks now in use will present a considerable problem. This raises the question of whether such personal protection equipment could be produced from bio-based materials that would be biodegradable.
”Only cellulose does not have that capacity since the filtering effect is not fully achieved”, Harlin says, explaining why a common paper material cannot be used for making protective masks. ”It is crucial to achieve that static charge and so far polypropene has turned out to be the most cost-effective material that could readily be scaled up in terms of production.”
Paper-based masks emerging
Sustainable options do exist, but upgrading them for commercial use is slow given the technology required for their production. ”But there are now technologies to make a bio-based product work, the challenge is just to do it at an industrial scale”, Harlin believes.
Having researched and compared the efficacy of surgical masks with textile masks made of of different materials, polyester seems a better option than the cotton-masks favoured by many for its softness. A mask’s capacity to filter the air varies considerably depending on the fabric and the number of layers. However, the plastic waste caused by the large-scale use of disposable masks and related personal protective equipment such as gloves and gowns, strongly suggests the need to turn to other materials. To avoid the use of plastic fibre, which can be recycled rather than incinerated when collected, disposable masks using bio-based materials are entering the market.
Different types of masks protect against aerosol droplets to varying degrees. The best surgical masks protect against small aerosol droplets while fabric masks are only good for dealing with droplets bigger than three micrometers. Two layers of tissue paper on top of a layer of textile protects almost as well as a plastic fibre surgical mask, but few have succeeded in exploiting paper-based materials on a commercial scale. A wood-based material is biodegradable, unlike materials containing plastic fibre.
“The challenge is to make paper-based masks breathable, so it does not choke the user,” Harlin says.
Enters new bio-filtre fabric
One of the first to market disposable face masks made of paper is the Finnish-Swedish company Ahstrom-Munksjö, which just this week launched its new material for medical-use, face masks that are biodegradable and compostable. The material is mainly comprised of polylactic acid, a bio-based replacement for plastic, a biopolymer from sustainable sources. The new fabric is made up of a blend of cellulose fibres, which render the filter entirely bio-based.
“Using technology from our business and the expertise of the medical product development team, we were able to advance product functionality in our smart, fibre-based solutions. Having products that are sustainable, renewable, and biocompatible allows for the opportunity to provide environmentally-friendly options,” Stuart Nixon, VP, Beverage and Casing, Ahlstrom-Munksjö, stated.
Another new fabric with bio components is being developed for controlling infectious disease as well as other civil use applications. This entirely bio-based fabric can be used as an inner or outer layer of a non-medical face mask, since it is both breathable and biocompatible, having benefited from the technology used to produce medical fibre materials.