Study On Preparation And Properties Of Continuous Polyurethane Phase Change Fibers

The unidirectional thermal insulation function of traditional fibers is affected by climate and humidity,making it difficult to meet people’s requirements for comfort.Phase change fibers can utilize phase change materials to absorb or release thermal energy for bidirectional temperature control,which is currently a research hotspot.In the manufacturing technology of phase change fibers,melt spinning is a clean method that doesn’t use any solvents.Melt spinning is the use of PCMs or microencapsulated PCMs mixed with polymer solution and melt to spun into continuous phase change fibers,playing an extremely important role in the preparation of continuous phase change fibers.Unfortunately,the phase change fibers obtained by the above melt spinning method suffered from low phase transition enthalpy due to the limited addition of PCMs to the polymer melt,resulting in poor thermal management capability.In addition,phase change fibers generally have poor conductivity,thermal conductivity,and light absorption,and low conversion efficiency for different forms of energy(such as light and electricity),which limits the application range of phase change fibers.In this paper,based on the analysis of the above problems,polyurethane phase change materials(PUPCM)with high phase transition enthalpy are synthesized,and prepared continuous polyurethane phase change fibers(PUPCFs)are prepared by melt spinning method with PUPCM as raw materials.Furthermore,multi walled carbon nanotubes with strong light absorption,high conductivity,and thermal conductivity were introduced into PUPCM after acid treatment,and continuous polyurethane phase change fibers with photo/electro thermal conversion functions were prepared by melt spinning method.The main details are as follow:Polyurethane phase change material(PUPCM)was synthesized with polyethylene glycol as phase change component.A continuous polyurethane phase change fiber(PUPCFs)with high phase change enthalpy(about 110 J/g)was prepared by melt spinning method.In order to optimize the spinning process,the effect of draw ratio on the performance of PUPCFs was investigated.The results showed that with the increase of draw ratio,the surface of PUPCFs became smoother,and the degree of orientation and crystallinity increased.Draw ratio increased and then decreased the breaking strength of PUPCFs.When the draw ratio was 6,the breaking strength reached its highest point at 1.20 c N/dtex,while the breaking elongation of PUPCFs decreased with the increase of drawing ratio.The PUPCFs prepared by optimizing the process exhibited great mechanical properties,with breaking elongation of 141.38%.Moreover,PUPCFs still exhibited superior elastic recovery performance after 100 tensile cycles when the strain is less than 40%.PUPCFs also exhibited smooth surface morphology and excellent thermal cycling stability,maintaining a high phase transition enthalpy(approximately 110 J/g)after 100 thermal cycles.Further,PUPCFs could be woven into textile and modified with PDMS to obtain thermal regulation textile(PUPCT/PDMS),which had good flexibility,hydrophobic breathability and excellent bidirectional temperature regulation function.It is believed that this work will bring inspiration for efficient and economical preparation of continuous phase change fibers.In order to improve the energy utilization efficiency of phase change fibers and expand its application range,multi walled carbon nanotubes after acid treatment with strong absorbance,high conductivity,and thermal conductivity were introduced into PUPCM with high phase change enthalpy to prepare polyurethane/multi walled carbon nanotube composite phase change materials.Polyurethane/multi walled carbon nanotube composite phase change fibers(A-M/PUPCFs)were prepared by melt spinning.The influence of A-M content on the properties of A-M/PUPCFs was explore,the results showed that with the increase of A-M content,the orientation,crystallinity,and fracture strength of A-M/PUPCFs showed a trend of first increasing and then decreasing.In addition,after adding A-M,A-M/PUPCFs still had higher phase transition enthalpy(>90 J/g),excellent thermal stability,and significantly improved thermal conductivity.Furthermore,A-M/PUPCFs-3 were woven into phase change textile(A-M/PUPCT),which exhibited high enthalpy of phase change and excellent thermal cycling stability.At the same time,the A-M endowed A-M/PUPCT with good light absorption,thermal and electrical conductivity.As a result,A-M/PUPCT could be heated from room temperature to 80.47°C under sunlight radiation of 120 m W/cm~2 for320 s,and the photo-thermal conversion efficiency could achieve 80.69%.In addition,under a constant voltage of 8 V for 480 s,A-M/PUPCT could be heated from room temperature to 78.10°C,and the electro-thermal conversion efficiency reached 56.26%.It is believed that the work has considerable potential applications in improving energy utilization efficiency and thermal management.