Study on thermal comfort of aloe viscose seamless knits

Aloe viscose fiber is rich in a variety of active ingredients, with excellent moisturizing and antibacterial properties, and gradually widely used in clothing production. Therefore, this paper focuses on the thermal comfort of aloe viscose seamless knitted clothing, 15 sets of seam knitting sets with different yarn blending ratios and knitted structures were designed. thermal manikin was used in artificial climate to test the thermal resistance and the voting rate of whole body thermal sensation. SPSS two-factor variance analysis and Duncan multiple comparison method were used to analyze the experimental data. The results show that the difference of veil material and knitted structure has an impact on clothing thermal comfort. In all the samples, the veil is made of 100:0 aloe viscose/viscose fiber, and the thermal comfort of the seam knitting garment w Abstract: In order to study the thermal comfort performance of aloe viscose fiber seamless knitted clothing, 15 sets of seam knitting sets with different yarn blending ratios and knitted structures were designed. Thermal manikin was used in artificial climate to test the thermal resistance and the voting rate of whole body thermal sensation. SPSS two-factor variance analysis and Duncan multiple comparison method were used to analyze the experimental data. The results show that the difference of veil material and knitted structure has an impact on clothing thermal comfort. In all the samples, the veil is made of 100:0 aloe viscose/viscose fiber, and the thermal comfort of the seam knitting garment with the knitted structure of 1 + 3 false rib fabric is the best, with the sets thermal resistance of 0.289 m2 K/W and the sets PMV value of −1.75. It provides theoretical basis and guiding significance for the future production of aloe seamless knitted clothing with excellent thermal resistance.


Introduction
2][3] Aloe viscose fiber is also becoming more popular in clothing fabrics.Clothing's thermal and the experimental clothing is made on a Santoni Company, Italy, SM8-TOP2 electronic seamless knitting circular machine.Based on a thermal manikin simulation of a real human body, the exchange between the human body, clothing, and environment was tested, as well as the thermal resistance of clothing and the predicted mean vote rate (PMV) of whole body heat sensation, in order to investigate the influence of the blending ratio and knitted structure of veil raw materials on the thermal comfort performance of seamless knitting clothing, which has important reference value for the development. 7,8

Establishment of material scheme
As the inner yarn, 11.81 tex (50 s) Aloe Viscose yarn and aloe viscose/viscose blended yarn developed by Shandong Hengfeng New Yarn and Fabric Innovation Center Co., Ltd. and 11.81 tex (50 s) viscose yarn developed by Shandong Dezhou Huayuan Ecological Science and Technology Co., Ltd. are used, and 2.22 tex/3.33 tex(20D/30D).
The full-factor experimental design method was used, 9 with the raw material and veil structure serving as experimental factors.The blending ratio of the veil's raw material aloe viscose/viscose yarn was five levels, which were 0:100, 25:75, 50:50, 75:25, and 100:0.There are three organizational levels: plain stitch, 1 + 1 false rib fabric, and 1 + 3 false rib fabric (see Figure 1 for organizational chart).A total of 15 groups of clothing samples are established, with each group prepares three samples of the same clothing.For more information, see Table 1.

Experimental equipment
Artificial climate.The thermal manikin experiment was carried out in Zhejiang Sci-Tech University's artificial climate.The artificial climate is 5 m long, 3 m wide, and 2.5 m tall.The climate chamber has a temperature control range of −1040°C, an adjustment accuracy of 1°C, a humidity control range of 45%−75%, and an adjustment accuracy of 10%.The air duct system is top air supply and bottom air return, with a wind speed of 0.1 m/s controlled.The artificial climate room can simulate the temperature and humidity climate

Experimental methods
Thermal resistance test.Open the artificial climate and configure its parameters in accordance with ISO 15831-2004 "Measurement of thermal insulation using a thermal manikin." 10 The temperature is sets to 22°C, the fluctuation range is 1°C, the relative humidity is sets to 50%, and the fluctuation range is sets to 10%.Fifteen groups of knitted garments were placed in the artificial climate cabin for 12 h prior to the test.Following the stabilization of the environment, the thermal manikin is placed in a standing position in the center of the artificial climate, with the feet raised to a height of 5 cm from the floor to eliminate conduction heat loss, as shown in Figure 3. Figure 3(a) shows the thermal manikin in the artificial climate, and Figure 3(b) shows the artificial climate. 11Start the thermal manikin, select constant temperature control mode, and sets the surface temperature of each part to 34°C.The skin temperature control accuracy is 0.1°C.According to Figure 1, areas 3, 4, 5, 6, 9, 10, 11, and 12 are designated as top grouping (hereinafter referred to as top grouping), and areas 13, 14, 15, 16,  17, 18, 19, and 20 are designated as bottom grouping (hereinafter referred to as bottom grouping) (hereinafter referred to as bottom grouping) The experimental dummy  was heated for more than 30 min and the heat flow of each section of the dummy was recorded every 1 min.Each group of clothing was tested three times, and the average of the three times was used to determine the final result of each group.
PMV test.Open the climate chamber and sets the parameters of the climate chamber according to ISO 7730-2005 Ergonomics of the thermal environment − analytical determination and interpretation of thermal comfort using calibration of the PMV and PPD indicators and local thermal comfort criteria. 12The air pressure is sets to standard atmospheric pressure, the temperature is sets to 22°c, the fluctuation range is ±1°c, the relative humidity is sets to 50%, and the fluctuation range is ±10%.Before the test, put 15 groups of knitted clothes in the artificial climate cabin for temperature and humidity regulation for 12 h.After the environment is stable, the test posture is placed in a standing position, which is consistent with the thermal resistance of the test clothing, because posture affects the prediction of thermal comfort by affecting the thermal resistance of the clothing. 13lace it in the center of the climate bin, and lift your feet to a height of 5 cm from the floor to eliminate heat conduction loss.Start the warm manikin, use comfort mode, and the value of each control area is closest to the real human condition.During the experiment, the manikin keeps heating for more than 1 h, and record the heat flow of each section of the manikin every 1 min.Each group of clothing was tested three times, and the average value of the three times was taken as the final result of each group.

Calculation method
Calculation method of thermal resistance.Clothing thermal resistance is classified into three types: total thermal resistance (I t ), relative thermal resistance (I clu ), and surface air layer thermal resistance (I a ).The dummy's total thermal resistance (I t,i ) at the I section can be calculated using (1).Where: T sk,i is the skin temperature of the I segment of the dummy's body in degrees Celsius; T a is the ambient temperature in °C; and H i is the heating flow rate for the I section of the dummy's body in units of W/m 2 .
Use parallel method to calculate the total thermal resistance of the whole body through (2).Where: f i is the ratio of the surface area of the first segment of the dummy to the total surface area.
The relative thermal resistance of clothing is the increase in thermal insulation over naked clothing, which can be calculated using (3), where I a is the thermal resistance of the air layer around the skin surface when naked.The study's findings include the relative thermal resistance of clothing.
PMV calculation method.Based on previous research findings, Danish scholars proposed the PMV (Predicted Mean Vote) index, which can predict thermal comfort using a large number of human physiological experiments and when combined with the thermal comfort equation of the human thermal balance equation. 14The comfort index of PMV is divided into sections based on the numerical interval of PMV through research on the quantitative method of numerical simulation data of PMV comfort in thermal environment (see Table 3 for details). 15MV can be calculated from (4, 5, 6, 7, 8). 11 In which: M is metabolic heat production of human body, W/m 2 ; W is the effective mechanical power, W/m 2 ; I cl is the thermal resistance of clothing, m 2 «K/W; f cl is the surface area coefficient of clothing; t a is the air temperature, °c; t r is the average radiation temperature, °c; V ar is the relative air speed, m/s; Pa is the partial pressure of water vapor, Pa; h c is the convective heat transfer coefficient, W/ (m 2 «k) ; t cl is the surface temperature of clothes, °c.

Study on fabric structure parameters and clothing thermal resistance
All experimental garments are tested and the results are recorded in accordance with the test standard.Table 4 displays the thermal resistance results of sets, tops, and bottoms.When the thermal resistance values of sets, tops, and bottoms of 15 groups of experimental garments are compared, it is clear that the thermal resistance values of all knitted underwear samples are greater than those of sets, and the thermal resistance values of tops are greater than those of bottoms.Because of the large gap area between the abdomen, waist, and clothing, which can accommodate more still air, the lower garment area has a relatively high thermal resistance.The tops has many exposed parts, such as the chest and hands, which causes its thermal resistance to be lower than that of the lower garment, while the sets is somewhere in the middle.Sets, tops, and bottoms have a thermal resistance of F12, which means that the yarn is aloe viscose/viscose 100:0 yarn and the organizational structure is 1 + 3 false rib fabric.
The relationship between the material and structure of the veil and the thermal resistance of clothing was explored further using SPSS two-factor analysis of variance.Table 5 depicts the two-factor variance analysis of clothing thermal resistance.Whether sets, top, or bottom, the clothing thermal resistance of different veil materials is significantly different (p < 0.05), as is the clothing thermal resistance of different fabric structures (p < 0.05).The interaction between veil materials and fabric structures is not significant (p > 0.05).According to the square value of Eta, whether it is suit, top or bottom, the influence of organizational structure on the thermal resistance of clothing is greater than that of veil material.
To compare the changes in veil raw materials and the differences between different levels of knitted structure, we use veil raw materials and knitted structure as factors, clothing thermal resistance as the dependent variable, and Duncan multiple comparison with one-way ANOVA to analyze the differences.Tables 6 and 7 show the outcomes.The data in the tables is analyzed and studied, and the following conclusions are reached.
(1) The blending ratio of aloe viscose/viscose fiber in the raw material of veil is 0/100, 25/75, and 50/50, indicating that there is no significant difference between these three levels.The aloe viscose/viscose fiber blending ratios are 75/25 and 100/0, indicating that there is no significant difference between these two levels.Aloe knitted underwear has a  higher thermal resistance than viscose knitted underwear, and moisture content is an important factor influencing fabric warmth retention.The fabric's moisture retention performance improves as the blending ratio of aloe viscose fiber in yarn increases, and a thicker air layer forms between the garment layers, resulting in a fabric with low thermal conductivity and good warmth retention.As a result, in terms of raw material adoption, aloe viscose/viscose fiber fabric has the greatest influence on clothing thermal resistance (100:0 > 75 :25 > 50:50 > 25:75 > 0:100).
(2) There are significant differences in organizational structure between plain stitch, 1 + 1 false rib fabric, and 1 + 3 false rib fabric.The thickness of the fabric has a significant impact on the thermal resistance of clothing.Because the 1 + 3 false rib fabric has the longest floating length and is the thickest, heat flow is difficult to lose through the fabric and thermal insulation is good.As a result, the order of influence of knitted structure on clothing thermal resistance is: 1 + 3 false rib fabric is better than 1 + 1 false rib fabric, and 1 + 1 false rib fabric is better than plain stitch fabric.

Fabric structure parameters and PMV research
Figure 4 and Table 8 show the test results in accordance with the test standard.When the PMV values of sets, tops, and bottoms are compared, it is clear that the comfort level of the same knitted sample garment is the same, and the PMV values of all knitted underwear samples are higher than those of sets, and the PMV values of tops are higher than those of bottoms.Furthermore, the PMV for sets, tops, and bottoms is F12, which means that the yarn raw material is aloe viscose/viscose 100/0 yarn and the organizational structure is 1 + 3 false rib fabric.
According to comparison Table 3, there are three levels of cold and warm feeling of the dummy in this test: very cold, cold, and slightly cold.This is because the dummy only wears a pair of knitted underwear at 22°C, and the thermal manikin obviously feels cold in this environment, so the PMV of the test results are all negative, with F01 and F13 in very cold grades, and F02, F03, F04, F05, and F06 in cold grades.However, the evaluation of reference comfort level only provides a broad range and cannot directly demonstrate differences in PMV between knitted samples.Table 7 shows the specific differences between each sample.The data obtained in this manner effectively avoids the impact of individual differences in human experiments, and the results are stable and consistent.
The relationship between veil raw materials, tissue structure, and PMV was investigated further using SPSS two-factor analysis of variance.Table 9 displays the results  of a two-factor variance analysis of PMV.There are significant differences in PMV of different veil materials (p 0.05) and PMV of different fabric structures (p 0.05) regardless of sets, top, or bottom, and the interaction between different veil materials and different fabric structures is significant (p 0.05).The influence of organizational structure on PMV is greater than that of veil material, according to the square value of Eta, whether it is sets, top, or bottom.
To compare the changes in yarn raw materials and the differences between different levels of organizational structure, yarn raw materials and organizational structure are treated as factors, and PMV is treated as a dependent variable, with the differences further analyzed using Duncan multiple comparison with one-way ANOVA.Tables 10 and 11 show the results.The data in the tables is analyzed and studied, and the following conclusions are reached.
(1) The blending ratio of aloe viscose/viscose fiber in the raw material of veil is 100/0 and 25/75, indicating that there is no significant difference between these two levels.The aloe viscose/viscose fiber blending ratios are 50/50, 75/25, and 100/0, indicating that there is no significant difference between these three levels.The thermal resistance of clothing is an important factor that influences human body comfort.At the same temperature, the thermal resistance of clothing has a significant impact on PMV.Previous experiments have revealed that increasing the blending ratio of aloe viscose fiber in yarn increases the clothing thermal resistance of fabric.This is because the fabric with a higher aloe content contains more water in the skin.A good microclimate is formed in the clothes as a result of proper air temperature and humidity, and the dummy feels more comfortable.Therefore, in terms of raw material selection, the order of influence on PMV is aloe viscose/viscose fiber fabric (100:0 > 75:25 > 50:50 > 25:75 > 0:100).
(2) On the organizational structure, plain stitch, 1 + 1 false rib fabric, and 1 + 3 false rib fabric each occupy a subset, indicating that these three levels differ significantly.The 1 + 3 false rib fabric has the highest underfill coefficient and the loosest structure, allowing gas to diffuse from inside to outside.Furthermore, the fabric thickness is thicker, and the temperature inside the garment is higher, creating a favorable microclimate.In terms of knitted structure, 1 + 3 false rib fabric is superior to 1 + 1 false rib fabric, and 1 + 1 false rib fabric is superior to plain stitch fabric.

Conclusion
Fifteen sets of knitted underwear samples were created for this paper.The thermal resistance and PMV of 15 sets of knitted underwear were tested using a thermal manikin testing instrument.The test data were analyzed using two-factor and one-factor variance analysis in SPSS software, as well as the Duncan multiple comparison method, and the influence of veil material and knitted structure on clothing thermal comfort was investigated.The following are the findings: (1) 15 sets of knitted underwear samples were tested for thermal resistance and PMV.Each knitted underwear sample had a higher thermal resistance and PMV than the sets, and the sets had a higher thermal resistance and PMV than the tops.This is due to the large gap area between the abdomen, waist and clothing, which can accommodate more static air, so that the thermal resistance of the lower garment area will remain relatively high.For the upper garment, there are many exposed parts of the warm manikin, such as the chest, hands, etc., which causes the thermal resistance of the upper garment to be lower than that of the lower garment, while the sets is between the two.
(2) In the thermal resistance test of clothing, the influence of fabric structure is greater than that of veil material, but both are significant.In terms of knitted structure, 1 + 3 false rib fabric outperforms 1 + 1 false rib fabric and 1 + 1 false rib fabric outperforms plain stitch fabric.In terms of veil raw materials, aloe fabric outperforms viscose fabric, and as the blending ratio of aloe viscose fiber in yarn increases, so does the thermal resistance of clothing.The knitted underwear sample F12 has the best thermal resistance, as the veil material is aloe viscose/viscose  100/0 yarn and the knitted structure is the seam knitting underwear sets with 1 + 3 false rib fabric weave.
(3) In the PMV test, organizational structure has a greater influence than veil raw materials, but both are significant.In terms of knitted structure, 1 + 3 false rib fabric outperforms 1 + 1 false rib fabric and 1 + 1 false rib fabric outperforms plain stitch fabric.In terms of veil raw materials, aloe fabric outperforms viscose fabric, and the PMV value increases as the blending ratio of aloe viscose fiber in yarn increases.The PMV is preferably a knitted underwear sample sets F12, with the veil material being aloe viscose/viscose 100/0yarn and the knitted structure being a seam knitting underwear sets with a 1 + 3 false rib fabric weave.
At the moment, aloe is widely used as a raw material with super moisturizing performance in the research and development of skin care products, 16,17 home textiles and industrial textiles, 18,19 but there is still a lack of research on the thermal comfort performance of aloe fiber clothing.This paper focuses on the effect of the veil raw material blending ratio and fabric structure on the thermal comfort of aloe viscose fiber clothing, which has important implications for the future production of aloe viscose knitted fabric with excellent thermal comfort.

Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figure 3 .
Figure 3. (a) Thermal manikin in artificial climate and (b) Schematic diagram of artificial climate.

Figure 4 .
Figure 4. Comfort level of each knitted underwear sample.

Table 2 .
Warm body dummy comparison table of various parts.

Figure 2. The warm manikin produced by PT TEKNIK Company in Denmark was used in the experience, with a height of 172 cm The thermal manikin system can
independently control the surface temperature and heat dissipation of 22 areas, and can group 22 areas to simulate the thermal resistance test and human comfort test Schematic diagram of each part of the warm body dummy.

Table 3 .
PMV values and human thermal sensation.

Table 4 .
Heat resistance of suits, tops, and bottoms.

Table 5 .
Two-way ANOVA analysis of thermal resistance in garments.

Table 6 .
Duncan multiple comparison table of the effects of different yarn raw materials on moisture absorption.

Table 8 .
PMV values for sets, tops, and bottoms.

Table 7 .
Duncan multiple comparison table of the effects of different tissue structures on hygroscopicity.

Table 9 .
Two-way ANOVA for PMV.* indicate that the value is too small to display, and a Sig.value less than 0.05 is interpreted as a significant impact of this factor on the results. *

Table 10 .
Duncan multiple comparison table of the effects of different yarn raw materials on moisture absorption.

Table 11 .
Duncan multiple comparison table of effects of different tissue structures on hygroscopicity.