Preparation Of Phase Change Microcapsule And Its Application On Thermoregulation Fabric

Thermal comfort of fabric is affected by its thermoregulation performance,which is one of the main factors that consumers consider when choosing fabrics.Thermoregulation fabric is a new type of thermal comfort textile containing phase change microcapsules,which can automatically sense the changes of external temperature and react to the changes in the form of absorbing or releasing heat.Thermoregulation fabric can not only provide thermal comfort for human body but also realize the recycling of heat energy,which conforms to the dressing concept and ecological requirements.Therefore,it is significantly important to develop the thermoregulation fabric.Based on the requirements of phase change microcapsules for fabrics,choosing the suitable core materials,wall materials and synthesis methods of microcapsules,optimizing the synthesis process to prepare microcapsules with good performance,and applying the microcapsules to the cotton fabrics through appropriate finishing method,finally the cotton fabrics with thermoregulation performance were obtained.The main research contents and results were as follows:Firstly,the phase change microcapsule for fabric finishing was successfully synthesized by in situ polymerization,using octadecane as the core material and MUF resin as the wall material.The influence of process parameters including the type of wall material,emulsifier(SDS)dosage,pH value,emulsification time,the ratio of oil to water,the amount of MUF prepolymer solution,the molar ratio of melamine to urea on the morphology and thermal properties of microcapsules were systematically studied by single factor experiment.And the optimal synthesis process of microcapsules under the experimental system was determined as follows:the SDS dosage was 4%of octadecane,pH value was 5.5~6,emulsification time was 30min,the ratio of oil to water was 1:8,the amount of MUF prepolymer solution was 25g and the molar ratio of melamine to urea was 1:2.Secondly,the morphology,structure and thermal properties of the microcapsules prepared with the optimal synthesis process were characterized by a series of test including SEM,OM,POM,FTIR,XRD,DSC,TG and HS-POM.SEM showed that the microcapsule was spherical separately and the surface is smooth.OM results showed that the average particle size of the microcapsules was 12.2?m and the microcapsules with particle size ranging from 5?m to 20?m accounted for 79%,which indicated that the partical size distribution of microcapsules was concentrated.POM results showed that octadecane had been successfully encapsulated in MUF resin.FTIR and XRD results showed that the encapsulation did not affect the chemical structure and crystal structure of octadecane.DSC results showed that T_m and T_c of microcapsules were 27.91?and 26.71?respectively,which were close to the comfortable temperature of human body.The melting enthalpy and crystallization enthalpy of microcapsules were 223.3J/g and 222.6J/g respectively.And the content of core material in microcapsules was as high as 93.2%.TG results showed that,compared with octadecane,the initial weight loss temperature,the temperature of 5%weight loss and the final weight loss temperature were increased by 20?,34?and 250?respectively,which indicated that wall material possessed good compactness and strength.HS-POM showed that the microcapsules had good temperature sensitivity and the core material could melt or crystallize with the increase or decrease of temperature.And the microcapsules remained spherical during the process of changing the temperature.According to the above analysis,the microcapsules prepared with the optimal synthesis process were suitable for fabric finishing.Thirdly,the MUF/Octadecane microcapsules prepared with the optimal process were applied to cotton fabric by the combination of dip-padding and ultrasonic treatment,so that the cotton fabric could obtain the function of thermoregulation.The influence of impregnation method,the mass fraction of microcapsule suspension,the mass fraction of binder,ultrasonic power,ultrasonic time,baking temperature and baking time on the weight gain rate and washing resistance of cotton fabrics were studied by single factor experiment.Based on the results of single factor experiment,the optimal finishing process was determined as follows:the mass fraction of microcapsule suspension was 40%,the mass fraction of binder was 20%,ultrasonic power was 500W,ultrasonic time was 30 min,baking temperature was 120?and baking time was 3 min.After finishing,the melting enthalpy and crystallization enthalpy of cotton fabric was 11.27 J/g and 10.80 J/g respectively,and the cotton fabric had the function of thermoregulation in the temperature range from 29?~33?.After 5 times and 10 times of washing,the enthalpy retention of cotton fabric were 93.20%and 85.56%respectively,which reflected that the finished cotton fabric had good washing resistance.Lastly,the morphology and structure and wearability of cotton fabric treated with the optimal finishing process were characterized.And the results were as follows:SEM showed that the microcapsules were successfully embedded into the gap of fibers.EDS results showed that the content of nitrogen on the surface of cotton fabric increased to 13.5%.After finishing,the air permeability and moisture permeability of cotton fabric decreased by 15.5%and12.2%respectively,the quick and slow elastic recovery angles increased by 40.0%and 37.1%respectively,the hydrophilicity and breaking strength were not significantly affected.