预聚合条件对密胺树脂相变微胶囊包覆效率的影响

通过改变预聚合条件制备了一系列密胺树脂相变微胶囊,采用扫描电镜(SEM)、差示扫描量热仪(DSC)和热重分析仪(TG)对其进行表征。探究了微胶囊包覆效率的计算方法,并结合SEM的测试结果,系统地研究了甲醛与三聚氰胺(F/M)摩尔比、预聚合时间和预聚体质量分数等因素对包覆效率(E_n)的影响。实验结果表明,采用DSC-TG联用的方法计算得到的E_n可以更准确地表征相变微胶囊的包覆情况。E_n随F/M摩尔比的增加和预聚合时间的缩短而增大,随预聚体质量分数的增加先增大后减小。当F/M摩尔比为2.5,预聚合时间为30min,预聚体质量分数为10%时,所制备微胶囊的E_n可以达到88.6%。

Effects of Prepolymerization Conditions on the Encapsulation Efficiency of Phase Change Microcapsules Based on Melamine-Formaldehyde

A series of phase change microcapsules based on melamine-formaldehyde were synthesized under different prepolymerization conditions.The properties of obtained microcapsules were investigated by SEM,differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).The calculation of encapsulation efficiency was discussed.Combined with SEM,the effects of parameters including formaldehyde/melamine (F/M) mole ratio,reaction time and mass concentration of prepolymer on the encapsulation efficiency were studied systematically.The experimental results indicate that the encapsulation efficiency(En) based on the results of DSC and TGA can reflect the effects of these parameters more accurately.The encapsulation efficiency shows significant increase with the decrease of reaction time and the increase of F/M mole ratio.And it decreases after obvious increase with the rise of mass concentration.When the F/M mole ratio is 2.5,the reaction time is 30 min and the mass fraction of prepolymer is 10 ％,the encapsulation efficiency of fabricated microcapsules can reach up to 88.6 ％.