The influence of viscose fibre properties on the absorbency of feminine hygiene tampons: the pivotal role of cross-sectional geometry

Abstract: Feminine hygiene products, used by millions of women worldwide on a daily basis, come in various forms. Among them, tampons are a prominent type that aims to absorb menstrual blood directly in the vagina. However, the underlying mechanisms governing liquid absorption in tampons have received limited research attention and remain poorly understood. This study aims to investigate these mechanisms by examining the two main types of viscose fibres used in tampons and their effects when employed in tampon production. The sole distinction between the fibre types lies in their geometric shape—round or trilobal—while all other fibre parameters remain constant. To explore these mechanisms, tampon proxies made from these fibres were created and subjected to tests measuring liquid absorption. In addition, a novel method employing infrared thermography was utilized to infer the stored energy within the compressed tampon. Furthermore, individual fibres were characterised for chemical composition, surface properties, fine structure, liquid interaction, mechanical parameters, and friction behaviour. The results revealed that trilobal fibres exhibited higher tampon absorbency compared to their round counterparts, despite sharing similar chemical composition and comparable mechanical characteristics. This disparity can be attributed to the greater specific surface area of trilobal fibres, leading to enhanced liquid uptake through fibre swelling. However, single fibre swelling only accounted for a minor fraction of the total liquid absorbency of a tampon. The most influential fibre parameter was the geometric shape, as trilobal fibres facilitated the construction and maintenance of a bulkier network with increased available volume for liquid absorption. Graphic abstract: [Figure not available: see fulltext.]