Preparation And Performance Study Of Cool Feeling Polylactic Acid Fibers And Textiles

In today’s society of green and sustainable development,traditional petroleum based synthetic fibers are difficult to degrade in the natural environment,and the problem of huge energy consumption in the production process is becoming increasingly prominent.Green textiles have gradually become a competitive hotspot in the global textile industry,and the demand for developing environmentally friendly textiles is urgent.Polylactic acid(PLA),as a new type of bio based material,is renewable and can be naturally degraded into carbon dioxide and water in the environment,without causing pollution or damage to the environment.It attracts people’s attention and widely used in the field of green textiles.As the rapid development of economy,people have put forward more and higher requirements for the comfort performance of textiles and clothing.Contact cooling fabric,as a type of comfort fabric,can quickly transmit heat from the human skin during wearing,bringing a cool feeling,and is widely popular in summer clothing fabrics.In order to prepare PLA fabrics with contact cooling properties,boron nitride(BN)and shell powder(SP)were selected as functional powders to improve the thermal conductivity of PLA.Cooling PLA fibers were prepared by melt spinning method,and cooling PLA fabrics were woven.Firstly,BN/PLA,SP/PLA,and SP/BN/PLA composite materials were prepared by melt blending PLA with BN,SP,and SP/BN composite powders with different mass fractions(0.5%,1.0%,1.5%).Their thermal conductivity was tested,and the crystallization performance indicators of the composite materials and their isothermal crystallization kinetics at different temperatures were studied by DSC.The results show that both BN and SP improve the thermal conductivity of the composite material.The SP/BN composite powder has a more significant improvement effect on the thermal conductivity,reaching a maximum of 0.319 W/(m·K).Adding low mass fraction inorganic powder can improve the crystallinity of composite materials and shorten the half crystallization time.However,higher mass fraction inorganic powder will hinder the crystallization of composite materials.At the same time,as the isothermal crystallization temperature increases,the semi crystallization time of the composite material shows a trend of first decreasing and then increasing.Subsequently,BN/PLA,SP/PLA,and SP/BN/PLA composite materials with different mass fractions were melt spun,and the properties of the resulting fibers were characterized.The results indicate that as the mass fraction of inorganic powder increases,the fracture strength and elongation at break of the fibers gradually decrease.The fracture strength and elongation at break of SP/BN/PLA fibers are higher than those of BN/PLA fibers.The overall orientation of SP/BN/PLA fibers is higher than that of BN/PLA fibers.With the increase of mass fraction,the crystallinity of BN/PLA fibers shows a trend of first increasing and then decreasing,while the crystallinity of SP/BN/PLA fibers has always shown an upward trend.As the mass fraction of inorganic powder increases,the moisture regain and boiling water shrinkage of the fibers first decrease and then increase.This is because lower mass fractions of inorganic powder play a nucleating agent role in PLA,promoting the crystallization of PLA,thereby reducing the moisture absorption and improving the size stability of the fibers.As the mass fraction increases,inorganic powder begins to hinder the crystallization process and will produce more defects and pores,Improve the moisture absorption of fibers and reduce their dimensional stability.With the increase of inorganic powder mass fraction,the K/S value of the fiber has significantly improved,with the highest value rising from 8.3 to 15.2.Finally,the spun BN/PLA and SP/BN/PLA fibers were woven into plain weave fabric samples on a small sample loom,and the woven fabric samples were characterized for their various wearing properties.The results show that as the mass fraction of inorganic powder increases,the thermal conductivity of the fabric shows an upward trend,increasing from 0.093W/(m·K)to 0.178 W/(m·K)and 0.221 W/(m·K),respectively;After adding high thermal conductivity inorganic powder,the qmax value of the fabric was significantly increased,with the highest values reaching 0.201 J/cm~2·s and 0.215 J/cm~2·s,respectively,showing contact cooling performance.At the same time,as the mass fraction of inorganic powder increased,the qmax value of the fabric gradually increased.Compared with pure PLA fabric,the soaking time of cool PLA fabric is significantly shortened,the water absorption rate and liquid water diffusion rate are significantly accelerated,and the unidirectional transfer index is significantly improved.The various moisture absorption and rapid drying performance indicators of cool PLA fabric are between 4~5 levels,meeting the requirements for moisture absorption and rapid drying performance of summer clothing fabrics.As the mass fraction of inorganic powder increases,the moisture permeability of the fabric gradually increases,with the highest increasing from 214.3g/m~2·h to 294.1 g/m~2·h and 296.0 g/m~2·h,indicating that the addition of inorganic powder can significantly improve the moisture permeability of PLA fabric.The breathability of cool PLA fabric is around 240-280 mm/s,and there is little difference in the breathability of cool PLA fabrics with different inorganic powder types and mass fractions.This indicates that the addition of inorganic powder has little effect on the breathability of the fabric under the weaving process designed in this study.