This study investigated the effectiveness of nonwoven and woven fabrics in improving the performance of all-cotton masks. The researchers evaluated individual materials based on their quality factor (Q), which combines filtration efficiency and breathability, against particles with aerodynamic diameters ranging from 0.5 to 5 microns. Nonwoven polyester and nonwoven polypropylene demonstrated higher quality factors than woven materials such as flannel cotton, Kona cotton, and sateen cotton. Materials with meltblown nonwoven polypropylene were found to filter best, particularly against submicron particles. The researchers then combined high-performing fabrics into multi-layer sets and evaluated their quality factors before and after a washing protocol that included machine washing, machine drying, and isopropanol soak. Sets incorporating meltblown nonwoven polypropylene designed for filtration degraded significantly post-wash in the submicron range where they excelled prior to washing. Washing caused lesser quality degradation in sets incorporating spunbond non-woven polypropylene or medical wraps. Post-wash quality factors were similar for all multi-layer sets in this study but higher than Kona quilting cotton. Washed multi-layer sets filtered between 12-42 percent of particles with a diameter of 0.5 microns, between 27-76 percent of particles with a diameter of one micron, between 58-96 percent of particles with a diameter of 2.8 microns, and between 72-100 percent of particles with a diameter of 4.2 microns. The filtration and pressure drop measurements of both homogeneous and heterogeneous multi-layer fabric combinations agreed with the estimations from the layering model. Overall, this study provides valuable insights into the effectiveness of different fabrics in improving mask performance and highlights the importance of considering washing protocols when evaluating their efficacy.
Scientists studied different types of materials to see which ones make the best masks. They found that some special fabrics called "nonwoven polyester" and "nonwoven polypropylene" work better than regular cotton. The best material for filtering tiny particles is called "meltblown nonwoven polypropylene". However, this material doesn't work as well after it's been washed. All the multi-layer masks they tested worked pretty well, but not as well as the meltblown nonwoven polypropylene on its own. Scientists used a model to predict how well different layers of fabric would work together in a mask.
Definitions
- Nonwoven: A type of fabric that is made without weaving threads together.
- Polyester: A type of synthetic (man-made) fiber often used in clothing and other textiles.
- Polypropylene: A type of plastic often used in packaging and textiles.
- Flannel cotton, Kona cotton, sateen cotton: Different types of woven cotton fabrics.
- Meltblown: A process where hot air is blown onto a material to create very small fibers that can filter out tiny particles.
- Filtration: The process of removing unwanted particles from a substance (in this case, air).
- Pressure drop: The decrease in air pressure caused by something blocking or slowing down the flow of air (like a mask).
The Effectiveness of Nonwoven and Woven Fabrics in Improving the Performance of All-Cotton Masks
Masks have become an essential part of our lives during the COVID-19 pandemic, but not all masks are created equal. This study investigated the effectiveness of nonwoven and woven fabrics in improving the performance of all-cotton masks. The researchers evaluated individual materials based on their quality factor (Q), which combines filtration efficiency and breathability, against particles with aerodynamic diameters ranging from 0.5 to 5 microns.
Nonwoven Polyester and Polypropylene Demonstrated Higher Quality Factors Than Woven Materials
Nonwoven polyester and nonwoven polypropylene demonstrated higher quality factors than woven materials such as flannel cotton, Kona cotton, and sateen cotton. Materials with meltblown nonwoven polypropylene were found to filter best, particularly against submicron particles.
Multi-Layer Sets Incorporating Meltblown Nonwoven Polypropylene Degraded Significantly Post-Wash
The researchers then combined high-performing fabrics into multi-layer sets and evaluated their quality factors before and after a washing protocol that included machine washing, machine drying, and isopropanol soak. Sets incorporating meltblown nonwoven polypropylene designed for filtration degraded significantly post-wash in the submicron range where they excelled prior to washing. Washing caused lesser quality degradation in sets incorporating spunbond non-woven polypropylene or medical wraps. Post-wash quality factors were similar for all multi-layer sets in this study but higher than Kona quilting cotton.
Filtration Results After Wash Protocols
Washed multi-layer sets filtered between 12–42 percent of particles with a diameter of 0.5 microns, between 27–76 percent of particles with a diameter of one micron, between 58–96 percent of particles with a diameter of 2.8 microns, and between 72–100 percent of particles with a diameter of 4.2 microns. The filtration and pressure drop measurements of both homogeneous and heterogeneous multi-layer fabric combinations agreed with the estimations from the layering model used by the researchers to evaluate mask performance pre/post wash protocols..
Conclusion
Overall, this study provides valuable insights into the effectiveness of different fabrics in improving mask performance and highlights the importanceof considering washing protocols when evaluating their efficacy
This study explores nonwoven and woven fabrics to improve upon the performance of the widespread all-cotton mask, and examines the effect of layering, machine washing and drying on their filtration and breathability for submicron and supermicron particles. Individual materials were evaluated for their quality factor, Q, which combines filtration efficiency and breathability. Filtration was tested against particles 0.5 to 5 micron aerodynamic diameter. Nonwoven polyester and nonwoven polypropylene (craft fabrics, medical masks, and medical wraps) showed higher quality factors than woven materials (flannel cotton, Kona cotton, sateen cotton). Materials with meltblown nonwoven polypropylene filtered best, especially against submicron particles. Subsequently, we combined high performing fabrics into multi-layer sets, evaluating the sets quality factors before and after our washing protocol, which included machine washing, machine drying, and isopropanol soak. Sets incorporating meltblown nonwoven polypropylene designed for filtration (Filti and surgical mask) degraded significantly post-wash in the submicron range where they excelled prior to washing (Q = 57 and 79 at 1 micron, respectively, degraded to Q = 10 and 15 post-wash). Washing caused lesser quality degradation in sets incorporating spunbond non-woven polypropylene or medical wraps (Q = 12 to 24 pre-wash, Q = 8 to 10 post-wash). Post-wash quality factors are similar for all multi-layer sets in this study, and higher than Kona quilting cotton (Q = 6). Washed multi-layer sets filtered 12-42 percent of 0.5 micron, 27-76 percent of 1 micron, 58-96 percent of 2.8 micron, and 72-100 percent of 4.2 micron particles. The measured filtration and pressure drop of both the homogeneous and heterogeneous multi-layer fabric combinations agreed with the estimations from the layering model.
