石蜡相变微胶囊的合成与表征

Synthesis and characterization of phase change paraffin microencapsules

以三聚氰胺-甲醛为囊壁,混合石蜡为芯材,通过原位聚合法合成相变储能微胶囊材料,采用单因素比较法和TEM、FT-IR分析手段研究了乳化剂、pH值和NaCl对相变微胶囊制备的影响。研究表明,乳化剂的种类对微胶囊的合成有着重要的影响;当体系pH值太大时,形成的微胶囊不够坚固,易被渗透,微胶囊化产率较低,而当溶液的pH值太小,酸性太强时,囊壁形成过快,质量不易控制,容易发生团聚和结块现象;在酸催化预聚体缩聚过程中,向体系中加入一定质量比的NaCl,可以得到更坚固的微胶囊材料。研究发现,当乳化剂为OP-10,pH为3.5,并加入NaCl时,密胺树脂成功的包覆上了石蜡芯材,其包裹率为80.4%,所合成的相变微胶囊,呈均匀分散的球形,外形完整,平均粒径为2.5μm,粒度分布比较窄,且具有很好的分散性。

The phase change microcapsules with melamine-formaldehyde cystic wall and mixed wax core material were fabricated by in-suit polymerization. The effects of emulsify types, pH value and NaCl on fabrication process were in vestigated by Fourier transform infrared spectroscopy （FT-IR）, differential scanning calorimetry （DSC）, transmission elec- tron microscope （TEM） and single-factor experiment. The results indicated that emulsify types affected synthesis of the mi- crocapsules greatly. When the pH value was too high, the microcapsules were easily permeated with fragile cystic wall and low productivity. While the pH value was too small, the growth rate of cystic wall was too big which would lead agglomera- tions in solution. Also, the addition of NaCl in the polycondensation process of acid-catalyzed prepolymer could enhance the toughness of cystic wall. When the pH value equaled 3.5 with the addition of OP-10 and NaCI, the wax core were success- fully coated by melamine resin with a high encapsulation rate of 80.4%. The microcapsules also achieved the best disper sion performance with a smallest average diameter and narrowest size distribution.