Jeans Pai Nai, Spotlight on Jeans Fashion
Moisture Management: Myths, Magic, and Misconceptions
Results indicated the overwhelming influence of fabric thickness, even though the finish treatment does inhibit absorption. Additionally, thickness was the primary factor controlling drying time. It is interesting to note that extrapolation of the thickness vs. drying time relationship indicated that cotton samples of the same thickness as the synthetic benchmark would have about the same drying time.
The absorption capacity of the cotton fabrics was up to 41% greater than that of the benchmark. Note that the cotton fabrics were 65-99% thicker than the benchmark. The greater thickness provides more space between fibers and between yarns for water to accumulate. In addition, the water absorbed by the cotton fibers was greater than for the benchmark material. Finishing the cotton reduced the capacity of the fabrics about 20%; but, as shown earlier, the wicking and transport rate were reduced.
By reducing fabric thickness to nearer that of the benchmark, the amount of water to be dried would also be reduced. Thus, an important experiment would be to calender the cotton fabrics to flatten them. If one could also finish the fabrics to reduce internal capacity of the cotton without slowing wicking rate, an additional significant reduction in drying time should be obtained.
In practical terms, if cotton fabrics with low levels of moisture remaining are perceived as comfortable, performance standards may be met without the fabric being dried to the baseline regain.
Wicking and Sorption of Calendered Fabric
After cold calendering at 10 kN, the thickness of the cotton fabrics was determined to be around 1.00 mm, which was greater than expected from previous laboratory experiments with fabrics 1 through 5 (0.7-0.9 mm). The thickness of the samples was evaluated after one and five wash cycles. Finish 2 (10% DMDHEU) and the benchmark increased the most. Almost all of the change was observed after the first wash. The water sorption capacity (as measured by GATS) of the test fabrics was generally related to thickness. Sorption capacity increased with wash cycles for all fabrics and increased more where the fabric increased more in thickness (S8-2).
It was found that the cotton fabrics exceeded both the wicking requirements for high performance moisture management fabrics (15 cm in less than 30 mm) and the wicking performance of the synthetic benchmark fabric. Wicking in the warp direction was found to be higher than in the weft direction in all cases. Washing was found to significantly increase the wicking rate of the cotton fabrics, but the DMDHEU-only treated fabrics (S8-l and S8-2) increased more. The DMDHEU/melamine sample was more stable to washing. The synthetic benchmark increased in wicking rate with washing, as well. Wicking results (average of warp and weft for each sample type) are shown in Figs. 5 and 6.
CONCLUSIONS
Thorough scouring and bleaching of cotton to remove residual waxes and oils has proven to be an effective means of increasing the wicking rate of cotton fabrics. Two of the fabrics tested were fully equivalent to the “high-tech” synthetic benchmark in wicking rate, and all of them would probably meet the usually accepted criteria for vertical wicking. The influence of construction variables such as yarn size and twist on wicking rates appears to be small. All of the fabrics (benchmark and cotton samples) required long drying times, but the drying of the cotton test items were extended due to the higher sorption capacity compared to the benchmark. The differences in dryness observed between the cotton fabrics and the benchmark are unlikely to be practically significant from a comfort viewpoint. Since the drying rate of the synthetic benchmark was only slightly different from the finished cotton samples, a key step to making faster drying cotton materials would be to make thinner structures.
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