Paraffin microcapsules with urea-formaldehyde polymer skin are prepared by in-situ polymerization of urea-formaldehyde prepolymer. It is found that the pH value of the aqueous solution, addition of NaCl and temperatur...Paraffin microcapsules with urea-formaldehyde polymer skin are prepared by in-situ polymerization of urea-formaldehyde prepolymer. It is found that the pH value of the aqueous solution, addition of NaCl and temperature affect the developing rate of microcapsules, and the most important appears pH value. The thermal properties of the microcapsules are explored by differential scanning calorimetry. The optimum conditions are:pH value 1.5, temperature 333.15～363.15 K, mass fraction of NaCl about 10%. The thermal analysis results show that the endothermic ability between 296.26 K and 308.15 K amounts to 9.11 J/g when the microcapsules undergo solid-liquid phase change at 300.53 K, the mean fusion heat of the microcapsule is 1.20 J/(g·K).展开更多
文摘Paraffin microcapsules with urea-formaldehyde polymer skin are prepared by in-situ polymerization of urea-formaldehyde prepolymer. It is found that the pH value of the aqueous solution, addition of NaCl and temperature affect the developing rate of microcapsules, and the most important appears pH value. The thermal properties of the microcapsules are explored by differential scanning calorimetry. The optimum conditions are:pH value 1.5, temperature 333.15～363.15 K, mass fraction of NaCl about 10%. The thermal analysis results show that the endothermic ability between 296.26 K and 308.15 K amounts to 9.11 J/g when the microcapsules undergo solid-liquid phase change at 300.53 K, the mean fusion heat of the microcapsule is 1.20 J/(g·K).
