Characterization of microfibers released from chemically modified polyester fabrics — A step towards mitigation

Synthetic textiles are one of the significant contributors to microfiber pollution, a subclass of microplastics. The impact of microfibers on the environment is irreversible. Several attempts were made to mitigate and control the microfiber release from synthetic textiles by introducing filters and laundry aids in washing machines, whereas some came up with methods to modify the textile materials to release fewer fibers. Studies have related different textile properties with their microfiber release potential. However, moisture properties, one of the essential properties that determine comfort, are not well explored. Hence, this research attempted to mitigate the microfiber release by altering the hydrophilicity of the polyester fabrics through chemical treatment (sodium hydroxide) with the hypothesis that hydrophilicity reduces the microfiber release. Both woven and knitted polyester fabrics were treated with different concentrations of the alkali solution (0.25 M, 0.50 M, 0.75 M, 1.00 M) and evaluated for their microfiber release. Treated fabrics also showed variations in their moisture and physical properties. Woven fabrics showed reduced shedding compared to knitted fabrics due to their compact structure. The results showed that the increase in alkali concentration significantly reduced the microfiber release up to 89.6 % reduction with woven fabric (from 17.37 ± 1.55 fibers/sq.cm to 2.63 ± 0.23 fibers/sq.cm) and a reduction of 68 % was noted for knitted fabric treated with 0.75 M alkali concentration (from 24.38 ± 1.30 fibers/sq.cm to 8.74 ± 1.39 fibers/sq.cm). A higher negative correlation (r = 94 % for woven and 89 % for knitted) was noted between alkali concentration and microfiber release. The alkali treatment significantly reduced the average fiber length from 450 to 230 μm, and 63-93 % of the fibers identified were in size range of 100-500 μm. When the moisture properties of the alkali-treated fabrics are concerned, an increase in moisture properties reduces the microfiber release. Water contact angle and absorbency time positively correlated with microfiber release. However, the study did not show any significant effect of moisture regain percentage and vertical wicking on microfiber shedding. Except for abrasion resistance, the physical properties of alkali-treated fabric did not show any relationship with microfiber release. The study noted the order of factors influencing the microfiber release of polyester fabric as fabric structural parameters (Woven/Knits) > fabric hydrophilicity > fabric physical property.