Physical characteristics, fiber compositions, and tensile properties of nonwoven wipes and toilet papers in relevance to what is flushable.

Numerous products, such as moist wipes, are marketed worldwide as "flushable." Recent studies indicate that wipes cause operational problems (e.g., pipe blockages) in sewer systems. This study investigates potential reasons for why wipes are problematic in sewer operations. Physical characteristics, fiber compositions, and tensile properties of non-flushable wipes, flushable wipes, and toilet papers (TPs) were assessed. Flushables, non-flushables, and TPs, respectively, had sheet masses of 1.5, 1.5, 0.5 g; surface areas of 250, 300, and 120 cm2 per sheet; thicknesses of 360, 370, and 160 μm; and volumes of 9.2, 11, 1.9 cm3 per sheet. While TPs were made of only plant-based fibers, wipes contained plant-based, and regenerated-cellulose (RC) fibers at various ratios, including up to 100% RC fibers. For tensile strength, the maximum force to break a specimen (Fmax) averaged 3 N for dry TPs, and 0.26 N for wet TPs. In contrast, the average Fmax values were 7 N for dry flushables and 5.9 N for their wet sheets. In wet states, TPs lost their strength by an average of 91%, but flushable wipes had variable changes: some wipes gained wet strength by 25%, some lost as much as 90%, and the average effect was a reduction by 29%. Thus, nonwoven wipes retain their strength and structure when wet, presumably because they contain RC fibers, which are known for their high wet strength. Accordingly, using synthetic fibers in flushable wipes seems to be the key reason for why the wipes cause operational problems in sewer systems.