Preparation And Phase Change Properties Studying Of Emulsion Electrospun Dodecanol/Polyvinyl Alcohol Nanofibers With Core-Sheath Structure

Phase change material（PCM）is a new type of material.When PCM is added to textiles,the temperature of the "microenvironment" between the textile and the human body can be in an appropriate range through phase change,and the thermal comfort of the human body can be maintained.Phase change fiber is one of the common forms of phase change materials in textiles.By encapsulating the phase change material inside the core-sheath structure fiber,the liquid leakage problem that occurs when the PCM undergoes a solid-liquid state transition can be solved.Electrospinning process can produce nano-scale core-sheath structure phase change fibers,which have a series of advantages such as large specific surface area,high phase change efficiency,and fast thermal response.The current commonly used method is coaxial electrospinning;However,coaxial electrospinning has higher requirements for spinning equipment,and the preparation process is uncontrollable,so its application is limited.In contrast,the spinning device required for emulsion electrospinning is simpler,and only a uniaxial spinneret is required to prepare nanofibers.Therefore,it has important research significance and application potential to realize the forming of phase change fiber with core-sheath structure through emulsion electrospinning.For this reason,dodecanol（DD）and polyvinyl alcohol（PVA）are taken as the research objects in this article,and the research content is divided into three parts accordingly:（1）Research on the forming mechanism of the core-sheath structure of nanofibers in emulsion electrospinning.Sodium dodecylbenzene sulfonate（SDBS）and sorbitan monooleate（Span80）were selected as emulsifiers,DD was the dispersed phase material,and PVA was the continuous phase material.The obtained spinning emulsion was subjected to electrospinning.The viscosity,conductivity of emulsion and morphology of the electrospun fiber at different positions of the jet were tested.Based on this,the mechanism model of the formation of the emulsion electrospun nanofiber core-sheath structure was proposed and the influence of the spinning emulsion components on the fiber morphology was explored.（2）Research on the phase change performance of nanofiber with core-sheath structure by emulsion electrospinning.Based on the conclusion of the previous chapter,SDBS was determined to be the emulsifier,the content of PVA was determined to be 10wt%,and DD was used as PCM.Spinning emulsions with different SDBS content and DD content were prepared,and nanofibers were obtained after electrospinning.The stability and spinnability of the spinning emulsion,the morphology,phase change performance,temperature regulation performance,leakage resistance and thermal cycle stability of nanofibers were studied.（3）Preparation and performance study of glutaraldehyde（GA）cross-linked phase change fiber.The content of SDBS was determined to be 1wt% and the content of DD was determined to be 8wt%.In order to improve the water resistance of the phase change fiber,GA was used as a crosslinking agent to obtain a crosslinked spinning emulsion,which was electrospun to obtain a glutaraldehyde（GA）crosslinked phase change fiber.Infrared spectroscopy,morphology,phase change performance,thermal cycle stability and water resistance tests were performed on the phase change fiber,and the changes in the performance of the phase change fiber before and after GA crosslinking were analyzed.The research results show that:（1）When the emulsifier is SDBS,electrospun nanofibers with good surface morphology can be obtained.When the continuous phase content is 10wt%and above,the fiber can obtain a clear core-sheath structure.（2）When the SDBS content is1wt%,the spinning emulsion has good stability and spinnability,and the resulting fiber has a better morphology.When the content of PCM in the fiber is 8wt%,the phase change enthalpy value can reach 67J/g,and the maximum value of temperature regulation is 1.3℃.The latent heat loss of the fiber after 15 thermal cycles is not large,and it has good leakage resistance and thermal cycle stability.（3）The phase change temperature of 1wt%GA phase change fiber is more suitable,which is 25.0 ℃,the phase change melting enthalpy reaches 48.7J/g,the enthalpy loss rate after 15 thermal cycles is low and the mass loss rate after the water resistance test is only 5.18%.Fiber has good phase change performance,thermal cycle stability and water resistance.