聚丙烯蜡固-固相变材料的制备与工艺优化

针对聚丙烯蜡相变材料难以乳化分散、离子交联定型的问题,利用聚丙烯酸（PAA）羧基的亲水性,易离子化特性,设计了低聚合度聚丙烯酸（PAA）接枝聚丙烯蜡,以自乳化方法制备聚丙烯蜡乳液,通过常温离子交联,在水介质中、短周期内制备了聚丙烯蜡固-固相变材料（PPW SS-PCMs）。首先利用红外光谱仪、核磁共振波谱仪、扫描电子显微镜分析测试,探讨了丙烯酸的浓度及瞬时浓度对聚丙烯蜡（PPW）接枝产物自乳化能力的影响。然后,利用偏光显微镜、X射线衍射仪、差示扫描量热仪、热重分析仪对PPW接枝产物及PPW SS-PCMs的结晶性能、热稳定性做了测试和分析。结果表明：随着丙烯酸（AA）质量占比升高,定型相变材料的相变焓随AA含量的提升而下降。在一定范围内,通过提高AA瞬时浓度能提高改性PPW的自乳化能力,减少定型组分添加量。当AA、PPW、BPO质量比为0.36∶1∶0.05及滴加速率为9mL/min时,所制备的PPW SS-PCMs的结晶温度为52.46℃,结晶焓为-53.61J/g,储能效率为81.26%,具有较好的热稳定性。

Preparation and process optimization of polypropylene wax solid-solid phase change material

In view of the problems of difficult dispersion with emulsification and ion crosslinking of polypropylene wax phase change materials, the low degree of polymerization polyacrylic acid (PAA) grafted polypropylene wax was designed by taking advantage of the hydrophilic and easily ionized properties of polyacrylic acid (PAA) carboxyl group. The polypropylene wax emulsion was prepared by self-emulsification method. Polypropylene wax solid-solid phase change materials (PPW SS-PCMs) were prepared in aqueous medium in a short period. Firstly, the effects of acrylic acid concentration and instantaneous concentration on the self-emulsification ability of PP wax (PPW) graft products were investigated by means of infrared spectrometer, nuclear magnetic resonance spectrometer and scanning electron microscope. Then, the crystallization properties and thermal stability of PPW SS-PCMs and PPW SS-PCMs were tested and analyzed by polarizing microscope, X-ray diffrotometer, differential scanning calorimeter and thermogravimetric analyzer. The results show that the enthalpy of phase change materials decreases with the increase of acrylic acil (AA) content as the mass ratio of AA increases. In a certain range, the self-emulsification ability of modified PPW can be improved by increasing the instantaneous concentration of AA, and the amount of fixed components can be reduced. When the mass ratio of AA∶ PPW∶BPO was 0.36∶1∶0.05 and the drop acceleration rate was 9mL/min, the crystallization temperature, enthalpy and energy storage efficiency of the prepared PPW SS-pcms were 52.46℃, 53.61J/g, 81.26%, and has good thermal stability.