Preparation Of Phase Change Microcapsule Kapok Textiles And Study On Its Temperature Regulation Property

Phase change material(PCM)refers to the material that maintains its own temperature in a certain temperature range and stores and releases latent heat by changing the state of the material.Taking advantage of this property of PCM,temperature-regulating textiles can be prepared by finishing it inside the fiber or on the surface of the fabric.At present,the preparation methods can be divided into three categories: the spinning method is only applicable to chemical fibers;the padding and coating methods make the thermoregulatory textiles have low latent heat and poor air permeability;the hollow fiber filling method provides a stable form during phase change and high rate of loading,but the current research mainly focused on larger diameter chemical fiber,for the study of natural thermoregulatory fiber remains to be further.Kapok fiber(KF)is a natural fiber with a large hollow structure,high cellulose content,and large specific surface area.Microencapsulated phase change material(MPCM)is prone to physical deposition and chemical crosslinking inside the lumen and on the surface of the fiber.In this paper,a novel and simple vacuum impregnation method was used to load MPCM onto KF to prepare a natural thermoregulated fiber with good heat storage and release performance,high washing fastness,good comfort and breathability,and green sustainability.The main work of this paper is as follows:(1)Firstly,the suitable MPCM was selected from the microstructure,particle size,heat storage and release properties and thermal stability.Through the preliminary experiment of impregnation process,it is proved that the effect of the vacuum impregnation method on the preparation of kapok thermoregulatory fiber(KF/MPCM)is better than that of the water bath impregnation method.The effects of MPCM mass fraction,binder mass fraction,impregnation temperature and baking temperature on the weight gain rate and phase change enthalpy of KF/MPCM were investigated by single factor experiment.The optimum preparation process of KF/MPCM was obtained: the mass fraction of MPCM was 30%,the mass fraction of binder was 5%,the impregnation temperature was 45 ℃,and the baking temperature was 100 ℃.The KF/MPCM with a weight gain rate of 39.8% and a melting enthalpy of 18.42 J/g was obtained.(2)The pectin,wax and other impurities on the KF surface can be removed by treating KF with a light alkali solution,and the surface properties of KF and its interfacial interaction with phase change finishing solution can be changed.The alkali-treated thermoregulatory kapok fiber(Na@KF/MPCM)was prepared by vacuum impregnation method to further improve the loading rate of MPCM on KF.The weight loss rate of Na@KF,the weight gain rate of Na@KF/MPCM and the melting enthalpy of Na@KF/MPCM were taken as the indexes,and the concentration of sodium hydroxide,treatment temperature,treatment time and bath ratio were taken as the influencing factors.A four-factor and three-level orthogonal test was designed to obtain the best alkali treatment process: the alkali concentration was 2 g/L,the treatment temperature was 45 ℃,the treatment time was 30 min,and the bath ratio was 1∶100.The weight loss rate of Na@KF was 9.21%,the weight gain rate was 38.39%,and the melting enthalpy was 21.46 J/g.Compared with the unmodified KF/MPCM,the heat storage capacity increased by 16.50%.(3)The heat storage and release properties and washing resistance of 1# KF,2#KF/MPCM and 3# Na@KF/MPCM were analyzed and compared.Three kinds of thermoregulatory flakes were prepared with these three kinds of fibers as raw materials,and then the thermoregulatory performance,thermal conductivity,bulkiness and compression performance were tested and analyzed respectively.The results showed that the loading rates of MPCM on 2# and 3# thermoregulatory flakes were 25.72 % and 29.97 %,respectively,which had good heat storage and release properties.The weight retention rates after ten times washing were 97.81% and 97.73%,respectively,showing excellent washing fastness.In the process of heating and cooling,1# flake has no thermoregulatory capability,2# and 3# can significantly delay the temperature change of the fabric center and play a role in temperature regulation.The loading of MPCM increased the thermal conductivity of 2# and 3# flakes by 8.28 % and14.42 %,respectively,increasing the heat transfer efficiency between the human body and the core material of MPCM during heat storage and release.The bulkiness of 1#,2# and 3# flakes did not change significantly,but the loading of MPCM slightly deteriorated the compression resistance of 2# and 3#,and significantly reduced compression resilience.