Evaluation of length and fiber count determinations for natural and synthetic microfibers using the OpTest Fiber Quality Analyzer

Authors: Santiago Cintron, Michael; Fortier, Chanel; Nam, Sunghyun

Submitted to: Microplastics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/26/2024
Publication Date: 12/6/2024
Citation: Santiago Cintron, M., Fortier, C.A., Nam, S. 2024. Evaluation of Length and Fiber Count Determinations for Natural and Synthetic Microfibers Using the OpTest Fiber Quality Analyzer. Microplastics. https://doi.org/10.3390/microplastics3040045
DOI: https://doi.org/10.3390/microplastics3040045

Interpretive Summary: Microfibers are small fiber particles in the millimeter length range and can be classified as natural or man-made fibers. Many microfibers are generated through the home laundering and daily wear of textile garments. Microfibers released from man-made textiles are a global pollution problem marked by their slow biodegradation and steady environmental accumulation. Thus, the quantification and study of factors controlling the generation of microfibers is of interest. In the current study, an imaging system was employed to determine the fiber counts and fiber lengths of microfibers derived from cotton, flax, ramie, hemp, acrylic, polyester, viscose, and polyamide. Probe sonication of sample microfibers led to higher fiber counts compared to examinations where sonication was not used. Average fiber lengths were comparable for sonicated and non-sonicated sample microfibers, with only hemp and ramie samples showing statistically shorter microfibers following sonication. Detection estimates for cotton, viscose and ramie microfiber were high, at close to or higher than 100%. In contrast, the detection of synthetic microfibers of acrylic, polyamide and polyester showed 77, 43 and 14% detection, respectively. These observations confirm the significance of properly suspending the samples to accurately quantify microfibers with the imaging system. Furthermore, the reduced detection of the examined synthetic microfibers suggests limitations of the imaging system as a technique for direct comparison of natural and synthetic microfiber counts.

Technical Abstract: Microfibers are small fiber particles that range from 1 µm to 5 mm in length and can be classified as natural or man-made fibers. Many microfibers are generated through the home laundering and daily wear of textile garments. Microfibers stemming from synthetic textiles are a global pollution problem marked by their slow biodegradation and steady environmental accumulation. Thus, the quantification and study of factors controlling the generation of microfibers is of interest. In the current study, a Fiber Quality Analyzer-360 (FQA) imaging system was employed to determine the fiber counts and fiber lengths of microfibers derived from cotton, flax, ramie, hemp, acrylic, polyester, viscose, and polyamide. Probe sonication of sample microfibers led to higher fiber counts compared to examinations where sonication was not used. Average fiber lengths were comparable for sonicated and non-sonicated sample microfibers, with only hemp and ramie samples showing statistically shorter microfibers following sonication, and a marked uptick in very short microfibers (< 0.07mm) following sonication. FQA detection estimates for cotton, viscose and ramie microfiber were high, at close to or higher than 100%. In contrast, the detection of synthetic microfibers of acrylic, polyamide and polyester showed 77, 43 and 14% detection, respectively. These observations confirm the significance of properly suspending the samples to accurately quantify microfibers while using the FQA system. Furthermore, the reduced detection of the examined synthetic microfibers suggests limitations of the FQA as a technique for direct comparison of natural and synthetic microfiber counts.