Preparation And Properties Of Phase Change Wax/Polyvinyl Alcohol Composite Materials

Phase change materials(PCM)is a functional material that can suck up and make lots of latent heat free by changing the phase within a certain temperature or temperature scope.Phase change materials have high latent heat and temperature.appropriate,stability,low price and reusable properties.As a solid-liquid phase change material with good stability,paraffin is a hotspot in the research of phase change materials in recent years,but because solid-liquid phase change materials need to change the phase state during the phase change process and the liquid phase appears,poor packaging will lead to phase change The leakage of materials has hidden safety hazards,and the phase change materials in the package will cause phase separation and aging problems.The packaging materials will also reduce the thermal conductivity of the phase change materials.Adding phase change materials to the polymer matrix to prepare shaped phase change energy storage materials is a research hotspot of phase change materials in recent years.The three-dimensional network structure of the polymer material is used to fix the phase change materials dispersed in the structure to make them macroscopically solid.New phase change materials with different phase states can be made according to demand,and the phase change materials fixed therein undergo phase change.Leakage is unlikely to occur when changes occur,and the polymer as a supporting material can take advantage of its own performance.Polyvinyl alcohol has excellent water solubility and biodegradability.Commonly used non-toxic solvents dissolve to prepare composite materials.Its melting temperature and decomposition temperature are close to each other.It is necessary to lower its melting point before melt processing.The research content of this paper is mainly divided into two parts:one is using phase-change wax(PC-WAX)as the phase-change medium,polyvinyl alcohol(PVA)as the polymer matrix,and water(H2O)as the solvent;PC-WAX/PVA/H2O ternary blend fluid,ternary composite sheet and frozen colloid.Observe the compatibility of the three.Rotary rheometer was used to perform steady-state and dynamic rheological performance tests on the three,and the surface appearance and mechanical properties of the materials were tested and analyzed by differential scanning calorimeter,scanning electron microscope,and universal material testing machine.The second is to blend and extrude PVA water particles swollen with water with PC-WAX and MEPCM through the Haul-off device of the capillary rheometer,observe the morphology of the composite extrusion filament,and analyze the extrusion process parameters.Impact.Differential scanning calorimeter,thermogravimetric analyzer,and spandex elastic tensile tester were used to test and analyze the thermal and mechanical properties of the composite extrusion yarn.The results show that PC-WAX/PVA/H2O at a certain ratio has good compatibility after high-temperature and high-speed stirring.Even mixing can obtain a milky white viscous ternary blend.Under the steady-state rheological test,the homogeneously blended samples exhibit the properties of non-Newtonian fluids.Increasing the PC-WAX content or decreasing the H2O content will increase the apparent viscosity of the ternary blend and shear thinning behavior.obvious.In the ternary blend,when the amount of phase change wax added increased from 0 to 4.5,its non-Newton index decreased from 0.92 to 0.59,the structural viscosity index increased from 1.22 to 6.42,the non-Newtonian enhanced,the degree of structure increased.Increasing the temperature will reduce the shear viscosity and viscous flow activation energy of the ternary blend.As the shear rate increases,the sensitivity of the shear viscosity to temperature decreases.The obtained PC-WAX/PVA/H2O ternary composite sheet is a crystalline polymer,and the ternary jelly colloid is a viscoelastic polymer with a large amount of hydrogen bonding inside.The rotational rheometer test found that the storage modulus of the material is greater than the loss modulus,indicating that there is a network structure inside.Angular frequency and temperature affect the storage modulus and loss modulus of PC-WAX/PVA/H2O ternary jelly.The sensitivity of ternary jelly to temperature is greater than the angular frequency.Mechanical stretching proves that PC-WAX/PVA/H2O ternary composite sheet has good tensile properties and breaking strength.PC-WAX/PVA/H2O ternary jelly has better resilience,and ternary jelly has better swelling ability.The PVA after water swelling can obtain a stable yarn by melt extrusion at a temperature of 130℃.The PC-WAX/PVA and MEPCM/PVA blended extruded filaments obtained by blending PC-WAX and MEPCM and melt-extruded have a phase change function,and the melting temperature and crystallization temperature are slightly higher than the theoretical values.The phase change performance of MEPCM/PVA blended extruded yarn is slightly better than PC-WAX/PVA,but the mechanical properties are reduced.The thermal degradation temperatures of the two blended extruded filaments are between PC-WAX and pure PVA,MEPCM and pure PVA,respectively.