Lin Lin,Ziqi Li,Jian Zhang,Tonghua Ma,Renzhong Wei,Qiang Zhang,Junyou Shi
Phase change energy storage microcapsules were synthesized in situ by using melamine-formaldehyde–urea co-condensation resin (MUF) as wall material, n-octadecane (C18) as core material and styryl-maleic anhydride copolymer (SMA) as emulsifier. Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry and thermogravimetric analysis were used to study the effects of emulsifier type, emulsifier dosage, core–wall ratio and pH on the morphology and thermal properties of microcapsules. The results show that the pH of core material and the ratio of core to wall have a great influence on the performance of microcapsules. SMA emulsifiers and MUF are suitable for the encapsulation of C18. When the pH is 4.5 and the core–wall ratio is 2/1, the latent heat and encapsulation efficiency of phase transition reaches 207.3 J g−1and 84.7%, respectively. The prepared phase-change microcapsules also have good shape stability and thermal stability.
Wenyi Chen,Fangyuan Cheng,Caleb John Swing,Shuqin Xia,Xiaoming Zhang
Cinnamaldehyde is an active component of some plant essential oils, which has broad antibacterial activity. However, the strong volatility and instability of cinnamaldehyde limits its application. Cinnamaldehyde was encapsulated by liposomes, and the effects of core-wall ratio on the stability and antibacterial activity during storage were investigated. The particle size during storage showed that cinnamaldehyde liposomes with high core-wall ratios aggregated more easily, and the retention ratio of it can maintained at around 60%. The increase of cinnamaldehyde loading could reduce the fluidity of the liposome membrane. The antibacterial activity of cinnamaldehyde liposomes against Staphylococcus aureus during storage was investigated by fluorescence labeling and the killing log value. It was found that liposome-encapsulated cinnamaldehyde might still inhibit bacteria by destroying cell membrane integrity after storage and the persistence was more efficient than that of pure cinnamaldehyde. Therefore, liposomes could improve the stability and long-term antibacterial activity of cinnamaldehyde.
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