Abstract:

Objective As the greenhouse effect intensifies, the ambient temperature in summer becomes hotter. This research aims to alleviate that influence of the hot environment in summer on the sleep comfort of the human body, and solve the problems of hard texture, poor moisture absorption and air permeability, and poor heat dissipation of the traditionally made cool mat. From the perspectives of yarn selection and structure design, the soft mat fabric with soft hand feel, good air permeability, moisture absorption, moisture permeability, heat permeability and cooling properties was designed.

Method Three types of yarn with ultrahigh molecular weight polyethylene (UHMWPE) of 1.85 dtex, nylon with 1.62 dtex and polyester of 2.31 dtex and polyester with superfine polyester draw texturing yarn (DTY) of 0.24 dtex were combined into three groups of yarn. Using the knitted composite structure, three types of knitted soft mat fabrics were produced on KSC-132 domestic Longxing computerized flat knitting machine. The three types of woven fabrics are numbered as 1^#, 2^# and 3^# in turn. The two types of straw mats and rattan mats on the market selected in this paper were numbered 4^# and 5^# respectively. The softness, air permeability, moisture permeability, moisture absorption and moisture conductivity and cool sensibility of the fabric were tested, and were compared with the two types of mats on the market.

Results Fabric softness are shown that the longitudinal and transverse bending stiffness of 1^# to 3^# soft mat fabrics is less than 5.000 mN·cm, far less than 4^# straw mat and 5^# rattan mat, indicating that the softness of the 3 soft mat fabrics is better than the straw mat and the rattan mat. The air permeability test results of fabrics are shown that the air permeability of all 5 fabrics is 658.19, 303.79, 427.56, 59.82 and 961.74 mm/s, indicating that the air permeability of 5^# rattan mat is the best, 4^# straw mat is the worst, and the air permeability of 1^# soft mat fabric is better than that of 2^# and 3^#. The moisture permeability test results of fabrics shows that the moisture permeability of 1^#-3^# soft mat fabrics is 7 615.55, 7 539.22 and 6 801.41 g/(m²·24 h), while the moisture permeability of 4^# straw mat and 5^# rattan mat is much less than that of the three soft mat fabrics, indicating that the moisture permeability of 1^# soft mat fabric is the best. The results of the moisture absorption rating of the 5 fabrics demonstrates that 1^#-3^# soft mat fabrics soaking time and water absorption rate are rated at grade 3, suggesting that the 3 designed soft mat fabrics have good moisture absorption, and 4^# straw mat and 5^# rattan mat have lower water absorption rate which is less than grade 3, and they failed to meet the requirement, indicating that poor moisture absorption. The one-way transfer index for 1^# and 3^# fabrics are rated at level 3, indicating that only 1^# and 3^# fabrics have good wet conductivity. The test results of the cool sensitivity of fabrics show that the heat transfer coefficient of 1^# soft mat fabric is 54.05 W/(m²·℃), which is the largest among the 5 types of fabrics and has the best cool sensitivity. The performance evaluation of the 5 types of fabrics was conducted, and the result shows that the comprehensive rating value of 3 soft mat fabrics is greater than the 2 commercial mats, and the comprehensive evaluation value of 1^# fabric is 0.769 4, which is the largest among all 5 fabrics, indicating that its comprehensive performance is the best.

Conclusion Based on three combinations of fiber materials and one knitted double-sided stitch, three knitted soft mat fabrics were produced. A series of hot and wet comfort performance tests were conducted on these 3 soft mat fabrics, and the results show that the soft mat fabric with UHMWPE is better than the fabrics containing nylon and polyester in related performance. The 3 soft mat fabrics were compared to 2 commercial mats made from straw and rattan respectively, and the results show that the 3 soft mat fabrics are superior in softness, moisture permeability, and moisture absorption over the straw mat and rattan mat, and UHMWPE soft mat fabric introduced cool sensation which is better than the straw mat and rattan mat. For comprehensive evaluation and analysis of the hot and wet comfort performance of all 5 fabrics, the result is that the comprehensive performance of 1^# soft mat fabric is the best, and the comprehensive performance of straw mat and rattan mat is worse than that of the 3 soft mat fabrics, so the soft mat fabrics designed in this research can replace the straw mat or rattan mat as a good bed to deal with the hot sleep environment in summer.

Key words: knitting, cool-feeling fiber, ultrahigh molecular weight polyethylene, soft mat fabric, thermal-wet comfort