Maximum wetted radius indicates maximum radius of wetting area. According to SPSS One-way ANOVA results, the difference of top radius among all samples was significant (F(13,69) = 28.185, P = 0.000 < 0.05). The difference of bottom radius among all samples was also significant (F(13,69) = 28.185, P = 0.000 < 0.05) showed in Table 3. The maximum wetted radius is 50 mm in tester.
Table 3 The one-way ANOVA test of maximum wetted radius (top and bottom)Full size table
As Fig. 3 shows, to compare the sample group 1 (1-1, 1-2, 1-3, 1-4, 1-5) and sample group 2 (2-1, 2-2, 2-3, 2-4, 2-5) where GB1 used 100D polypropylene, full-thread and density(16–24 cpc), Structure I had larger maximum wetted radius (30 mm) than that of structure II (25–27 mm). It was also the same observation, when comparing samples 3 (radius in 30 mm) and 4 (radius in 27 mm) which were manipulated by 75D polyester, full-thread and 20cpc density, samples 5 (radius in 30 mm) and 6 (radius in 28 mm) where GB1 used 100D polypropylene, part-thread and 20 cpc density, Therefore, it proved that the structure I can spread water further. This might be the miss lapping in knitting create long float on the inner surface which can spread water in yarn but not between yarns. More interloop by yarns will impede conductive pathway and weaken the diffusion ability.
Fig. 3The results of maximum wetted radius by MMT test
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Under the same warp density (20cpc) and thread type, the result of wetted maximum radius was 30 mm for the sample 1-3 (100D polypropylene on GB1) and sample 3 (75D polyester on GB1) in structure I. But there was a difference between sample 2-3 (25 mm) and 4 (27 mm) in structure II. This might be there is a denser construction for structure II. Sample 4 had finer yarn which could spread liquid further.
Under the same warp density (20 cpc), GB1 treaded with 100D polypropylene, the result of wetted maximum radius was 30 mm for the sample 1-3 and sample 5 in structure I. But, sample 6 in structure II exhibited larger wetted radius than sample 2-3.
Under same thread type and structure, warp density did not affect the maximum wetted radius for structure I. But for structure II, the lower warp density could result in higher maximum wetted values.
In this study, when varied the density, material and thread type, no differences were found. Besides, there was no difference on the maximum wetted radius between top layer and bottom layer.
One-way transport capacity is the ability of liquid water to transfer from the top surface to the bottom surface is the ratio of the difference of water absorption on both sides of the fabric. According to SPSS One-way ANOVA results, there was a significant difference of one-way transport capacity among all samples (F(13,69) = 76.560. P = 0.000 < 0.05) showed in Table 4. One-way transport capacity presents the water content difference between face and back side. If the value is high, it means the top surface (close to skin) retain less water than bottom surface.
Table 4 The one-way ANOVA test of one-way transport capacityFull size table
From Fig. 4, when comparing sample group 1 and 2 which were made of same yarns, density and threading, structure I exhibited higher one-way transport capacity. The increase reached 103.57%, 86.91%, 102.75%, 86.77% and 158.67% correspondingly. Besides, when comparing the samples 3 and 4, samples 5 and 6 which were made of same yarn, density and thread type, structure I also exhibited higher values than structure II. This is due to miss lapping of structure I on GB1. The underlap at the back side of structure I is longer than that of structure II. The long float was not interstitched into the loop and appeared at the back. This could increase the continuous transport channels by which water can be directly transported along yarns but not by contact areas between yarns. It was prove that the large difference of hydrophilicity determined the one-way transport capacity, such as cotton (outer side)-polypropylene (inner side) fabric (Babu et al., 2020; Chen et al., 2020).
Fig. 4The results of one-way transport capacity by MMT test
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To compare samples 1-3 and 3 with different yarn on GB1 (in structure I, 20 cpc, and full thread), samples 2-3 and 4 with different yarn on GB1 (in structure II, 20 cpc, and full thread), the values of one-way transport capacity decreased from 133.05 (sample 1-3) to 61.9 (sample 3), and from 65.62 (sample 2-3) to 42.61 (sample 4). The decrease attained 144.83% and 54% respectively. It can be concluded that polypropylene used on GB1 could increase one-way transport capacity with comparison of polyester on GB1. Even more importantly, miss lapping used on GB1 could highly improve water transport. Firstly, this is because GB1 was threaded with polypropylene which is hydrophobic in both structures I and II. Furthermore, the longer float at the back side in structure I could make water flow easier than short underlap in structure II.
When thread type varied from full thread to part thread in structure I, sample 5 exhibited 182.17 which increased by 36.79% compared with sample 1-3 (133.05). For structure II, there was also increase by 80.8% from 65.62 (sample 2-3) to 118.66 (sample 6). This is probably that the density of underlap at the back side reduce to a half. The less water could be retained at the back side, and this increased the difference of water content retained between back and face side.
Regarding the effect of density on one-way transport capacity, it is interesting that for both structures I and II, the values increased to a peak from 16 to 20 cpc, and then decreased from 20 to 24 cpc. This demonstrated that the density at 20 cpc could help to reach the optimizing one-way transport for one-way transport capacity within groups 1 and 2.
Overall moisture management capacity is weighted values of water absorption rate, one-way transfer index and liquid water diffusion rate on bottom surface of fabrics. According to SPSS One-way ANOVA results, there was significant difference of overall moisture management capacity among all samples (F(13,69) = 38.540. P = 0.000 < 0.05) showed in Table 5. The value of overall moisture management capacity given by tester ranged from 0 to 1 (Fig. 5).
Table 5 The one-way ANOVA test of overall moisture management capacityFull size table
Fig. 5The results of overall moisture management capacity by MMT test
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When comparing the groups 1 and 2, samples in structure I always exhibited higher overall moisture management capacity than samples in structure II. Besides, When GB1 was full-threaded with 75 D polyester, samples 3 made in structure I and full thread also had higher values than samples 4. When GB1 was part-threaded with 100D polypropylene, sample 5 in structure I had higher values than sample 6 in structure II. This might be that the back side surface of sample 1-3 exhibited more hydrophobic properties than that of sample 3.
Base on same conditions such as structure I, 20 cpc, and full thread, samples 1-3 (0.6) with 100 D on GB1had higher overall moisture management than sample 3 (0.55) with 75D on GB1. Samples 2-3 and 4 were both in structure II. The former (0.53) had higher overall moisture management than the latter (0.51). The same conclusion was conducted that polypropylene used on GB1 could enhance the overall moisture management. As a results, the water absorption and transport difference of face side and back side could be enlarged.
When the number of thread reduced to 50% in structure I, sample 5 (0.63) had higher overall moisture management than sample 1-3 (0.6). For structure II, sample 6 (0.57) had higher overall moisture management than sample 2-3 (0.53). This might be that the relatively loose knitting structure could help to transport liquid water.
Regarding the effect of density on overall moisture management capacity, the same observation with one-way transport capacity was found. The samples with 20 cpc in structure I or II still reached the best performance.
According to SPSS One-way ANOVA results, there was significant difference of overall moisture management capacity among all samples (F(13,41) = 10.218. P = 0.000 < 0.05) showed in Table 6. As noted in Fig. 6, sample group 1 exhibited lower water vapor permeability than sample group 2 under same density by comparing samples in two structures correspondingly. This is because the long floats formed by miss-lapping in structure I could result fabric bulkier, the pores size within fabrics increase. In addition, the fabrics in group 1 had higher mass and thickness than that in group 2, the average increase by 4–6 g/m2 and 0.1 mm.
Table 6 The one-way ANOVA test of water vapor permeabilityFull size table
Fig. 6The results of water vapor permeability
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Samples 3 and 4 where GB1 threaded with 75D polyester had higher water vapor permeability than that of samples 1-3 and 2-3 where GB1 threaded with 100D polyproperlene. This is due to thinner yarn was used in samples 3 and 4 where mass and thickness reduced by 25–50 g/m2 and 0.1 mm.
As a result of the varition of thread type, sample 5 and 6 had higher water vapor permeability than samples 1-3 and 2-3 correspondingly. This is due to the fabric mass dropped from 155.2 to 87 g/m2 and 151.7 to 97.3 g/m2, and thickness dropped from 0.54 to 0.37 mm and 0.53 to 0.5 mm.
When density increased from the 16cpc to 24 cpc, there was no consistent conclusion drawn from structure I and II. For structure I, there was a increasing trend when warp density increased. This might be that the structure with long float become denser, less still air could trapped in fabric.
Figure 7 illustrates the air permeability test results. There was significant difference of overall moisture management capacity among all samples (F(13,69) = 410.387. P = 0.000 < 0.05) showed in Table 7. Compared with the results of water vapor permeability, the variation of knitting structure, yarn type, threading type as well as density could lead to much difference.
Fig. 7The results of air permeability
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Table 7 The one-way ANOVA test of air permeabilityFull size table
When yarn type, threading type, density were same, structure I had lower air permeability. This is because structure I had loose and bulky structure which resulted in higher fabric thickness (0.53–0.55 mm) and mass (152.7–160.8 g/m2). Structure II had relatively lower values (0.52–0.54 mm, 148.1–154.9 g/m2). Air permeability of fabric were determined by structure, yarn count, and density (Raja & Das, 2020).
According to the test results, sample 3 (3159.6 mm/s)and 4 (1902 mm/s)possessed much higher air permeability than sanples 1-3 (925.08 mm/s) and 2–3 (964.4 mm/s) at same density and structure. The GB1 of sample 1-3 and sample 2-3 were threaded 100D polypropylene, and that of sample 3 and sample 4 were 75D polyester. This is mainly due to the change of the yarn fineness, the decrease of the volume density and the increase of the porosity of the fabric.
When thread type varied from full to part, air permeablity of samples 5 (3305.2 mm/s)and 6 (2014.8 mm/s) increased highly compared with 1-3 (925.08 mm/s) and 2-3 (964.4 mm/s) respectively. It can be seen that the threading type imparted air flow, and the fabric with part-thread was better than that with full-thread. This is due to the thin thickness, light weight, small volume density, and more air exchange spaces. Therefore, the air permeability of sample 5 had highest values.
With the same raw material, threading type and structure, the influence of the density on the air permeability of the fabric was analyzed. The comparison group was sample 1-1 to 1-5, sample 2-1 to 2-5, and the warp density of samples was 16, 18, 20, 22, 24. It can be seen from the test results that the air permeability of the fabric decreased with the increase of the density of the fabric. When density increased from 16 to 24cpc, the air permeability decreased by16.6% for structure I, and by 15.6% for structure II. When the warp density was 16, the air permeability was the best, where sample 1-1 was 1029.20 mm/s and sample 2-1 was 1035.8 mm/s. The main reason that the structure II in the plain knit was tight. When the density of the fabric increases, the structure of the fabric becomes more compact, the volume density increases, and the channels for air pass through become less.
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