Preparation And Properties Of Thermoresponsive Composite Electrostatic Twisted Yarns Induced By Magnetic Field

Temperature-sensitive smart textiles have the ability to sense the temperature of the environment and actively self-regulate,with applications in intelligent temperature regulation,bio-medicine.In the 2022 Beijing Olympic Games,the US team has adopted a temperature-sensitive yarn that senses the ambient temperature to prepare their uniforms,enabling the garments have the ability to automatically change body temperature.Inspired by this,this project explores the feasibility of using temperature-sensitive poly(N-isopropylacrylamide)(PNIPAM),based on temperature-sensitive polyacrylamide,to design and prepare temperature-sensitive yarns through electrostatic spinning technology.In order to explore the potential of yarns prepared from P(NIPAM)in the biomedical field,the combination of the polymer’s nature of contraction by heat with the magneto-thermal conversion properties of magnetic particles Fe3O4 nanoparticles,which can be manipulated spatially under the stimulation of alternating magnetic fields,paves the way for its subsequent combination with biomedical materials such as drug release.In this project,the temperature-sensitive polymer PNIPAM was chosen as the source of the temperature-sensitive properties of the yarn.The temperature-sensitive polymer poly(N-isopropylacrylamide-co-4-acryloyloxybenzophenone)P(NIPAM-ABP)was first synthesised and the photocrosslinker 4-acryloyloxybenzophenone(ABP)was introduced during the preparation process to enable the polymer to be crosslinked under UV irradiation.The polymer was characterised using a series of characterisation methods to determine the molecular weight,polydispersity coefficient and LCST of the polymer and to determine the LCST of the polymer.Pure P(NIPAM-ABP)polymer films were prepared by electrostatic spinning method using the synthesized P(NIPAM-ABP),and the electrostatically spun fiber films were twisted by a film spooling device to prepare twisted yarns.The effects of film spooling twist,spinning solution concentration,film width and thickness on the basic properties and shrinkage of the yarns were investigated.It was found that the diameter,shrinkage,mechanical properties,abrasion resistance and water conductivity of the P(NIPAM-ABP)membrane spools were affected by the twist,spinning solution concentration,cut width and thickness of the membrane spools.After comparing the experimental results,select the appropriate parameters to produce twisted yarns.Although the properties were relatively good,the mechanical properties were poor,strength at break below 200 c N,elongation at break not exceeding 12%,which is needed further improvement.In order to enhance the mechanical properties of the polymer yarn before and after heat treatment,the blended yarn was prepared by blending thermoplastic polyurethane(TPU)with P(NIPAM-ABP),and three different blending ratios were prepared for the TPU/P(NIPAM-ABP)film.The addition of TPU was found to increase the mechanical properties of the twisted yarn,increasing the elongation at break to more than 80%,as well as increasing the abrasion resistance and water conductivity by more than two times.However,the introduction of TPU reduces the shrinkage of the yarn.It can be observed that the shrinkage of the blended film roll yarn decreases by more than 10% in the axial direction compared to the P(NIPAM-ABP)film roll yarn,and by more than 15% in the radial direction.Choose the blending ratio with both shrinkage and mechanical properties for further study.To explore the potential of yarns prepared from them in the field of biomedical excipients,magneto-thermally converted Fe3O4 particles were loaded into TPU/P(NIPAM-ABP)blended fibrous membranes to prepare composite membrane,and the effects of Fe3O4 particle loading and magnetic field strength on the temperature and shrinkage of the membrane were investigated.TPU/P(NIPAM-ABP)-Fe3O4 composite film’s temperature warms up faster and the higher,the more pronounced the shrinkage and the difference in the transverse and longitudinal shrinkage of the composite film.The effect of Fe3O4 loading and twist on the surface temperature of the twisted yarn,and the effect of twist direction and temperature on the shrinkage of the TPU/P(NIPAM-ABP)-Fe3O4 composite twisted yarns were investigated.In summary,this project has successfully prepared thermo-sensitive twisted yarns induced by magnetic field,the basic properties of the composite twisted yarns have been tested,characterized and optimized,and the factors and laws affecting the magnetic induction and shrinkage properties of the yarns have been investigated.