Design and process optimization of binary low eutectic fatty acid phase change microcapsules

The phase transition temperature of single fatty acids is generally high and prone to leakage， which cannot meet the demand for using them as phase change materials for regulating the energy consumption of building air conditioning in summer.Based on conductor-like screening model for real solvents （COSMO-RS），136 binary low eutectic fatty acids of 7 medium chain fatty acids and 10 long chain fatty acids were designed and calculated by using COSMOthermX software，and the eutectic temperature and molar ratio of binary low eutectic fatty acids were predicted.Furthermore， the optimal combination was used as the core material， and melamine-urea-formaldehyde （MUF） resin was used as the wall material to prepare phase change microcapsules through in-situ polymerization. The effects of different process conditions （core-to-wall ratio， reaction temperature， reaction time， reaction speed，etc.） on the thermal and physical properties of the microcapsules were systematically discussed. The results show that the COSMO-RS model can judge the relationship between hydrogen bond donor （HBD） and hydrogen bond acceptor （HBA） more intuitively. The eutectic temperature （33.25 ℃） in theory is 98.08% similar to the experimental temperature （33.1 ℃） of lauric acid （LA）-myristic acid （MA） （LM） with the optimal combination of LA and MA with a molar ratio of 0.66 to 0.34. Under the conditions of a core-to-wall ratio of 2∶1， reaction time of 3 h， reaction temperature of 80 ℃， and stirring speed of 200 r/min， the encapsulation efficiency of MUF on the core material LM is 61.37%， which effectively solves the leakage problem and has potential application value in reducing the energy consumption of building air conditioning refrigeration.