Abstract:

Objective When the ambient temperature changes suddenly, cotton products are weak to regulate the temperature, which affects the wearing comfort of the garment. Meanwhile, the moisture absorption of cotton fibres is strong, which makes the fabrics prone to breeding various microorganisms such as bacteria, fungi, algae and viruses. This is detrimental to human health. In order to improve thermoregulation and antibacterial ability of cotton fabrics, microencapsulated materials with thermoregulatory and antimicrobial properties were synthesised using microencapsulation technology. These materials were then used to treat cotton fabrics for enhancing their respective thermoregulatory and antimicrobial capabilities.

Method In this study, the microcapsule was prepared with the core materials including both n-octadecane, mugwort oil and the wall materials consisting of melamine urea-formaldehyde (MUF) resin by in situ polymerization method. The microcapsules with thermoregulation and antibacterial functions were then finished on pure cotton fabrics by dipping and rolling method. The microcapsules were characterized by scanning electron microscopy, laser particle size analyzer, Fourier infrared spectrometer, thermogravimetric analyzer and differential scanning calorimeter. The formaldehyde content, thermal insulation, thermal imaging, and antibacterial performance of the microcapsule finishing sample underwent testing as well as the temperature regulation and antibacterial properties of the fabric were evaluated.

Results Microcapsule materials with temperature regulation and antibacterial properties were prepared for this study. The results showed that, the microcapsules had a spherical appearance with a smooth surface and wear well-formed. The particle size was predominantly in the range of 1 100-2 500 nm, accounting for 95%, with an average particle size of 1 647 nm, demonstrating good uniformity. Infrared spectroscopy indicated that, the infrared spectral characteristic peaks of the microcapsules comprise the peaks of n-octadecane, mugwort oil, and MUF resin. This finding suggests that the wall material possesses excellent coating properties on the core materials. The latent heat test results and temperature of phase transformation indicate that, there are obvious heat absorption and exothermic peaks on the heating curve and cooling curve of microcapsules, and the phase transition temperatures of rising and cooling are 32 ℃ and 20 ℃. The enthalpy values for melting and solidification phase transition are 101.37 J/g and 107.93 J/g, indicating that microcapsules have strong heat storage capacity. The coating rate of prepared microcapsules is 74.3%. Thermal stability testing indicated that, the microcapsule exhibits great thermal stability at a temperature of 300 ℃, but experiences a high rate of weight loss once the temperature reaches 302.7 ℃. The pure cotton fabric with functions of thermoregulation and antibacterial was prepared. The results showed that, the formaldehyde content of the sample conforms to the national standard. The thermal resistance of the sample increased by 17.8%, and the insulation rate increased by 15.1% before washing, and after washing for 30 times, they are 26.5% and 23.2%. The sample thermoregulation capacity is 1.6 ℃ before washing, and after washing for 30 times, it is 1.4 ℃. The bacteriostatic rate of the samples against E. coli is more than 85% before washing, and after washing for 30 times, it is more than 40%. The bacteriostatic rate of the samples against Staphylococcus aureus is more than 97% before washing, and after washing for 30 times, it is more than 92%.

Conclusion The aforementioned test results show that, the formulated microcapsule material possesses a smooth surface, concentrated particle size dispersion, favorable coating ability, high latent heat of phase transformation, and good heat resistance, which can meet the requirements of the general conditions of textile processing. Additionally, cotton fabrics treated with this microcapsule material exhibit thermoregulatory and antibacterial properties. In the future, the research on microcapsules with phase change temperature regulation and antibacterial composite function for textile, it can be carried out from the shape and structure of microcapsules, size, thermal stability, and the combination technology of microcapsules and textile materials. This will enable the optimization of preparation technology for textiles with improved thermoregulation and antibacterial functions, thus enhancing the functionality and added value of textiles.

Key words: phase change energy storage, antibacterial, in situ polymerization, microcapsule, functional finishing, functional textile