Nanostructure Preparation And Thermal Performance Study Based On Octadecanoic Acid

Energy crisis is the bottleneck of restricting economic development, so the study for new energy resources and energy saving technology got the attention of people, energy storage technology with phase change materials can be used to solve the supply and demand of energy which does not match in with time, phase change materials can store energy and control temperature, which make they become the research hot spot on energy storage technology. Organic phase change materials do not existed supercooling and phase separation problems, and they have high latent heat, but low thermal conductivity and liquid leakage is the main problem of organic phase change materials. We make use of the nano technology in this paper, it effectively resolved the existed problems of organic phase change materials in store energy process. We chose the octadecanoic acid as the research object, we prepared different morphologies of octadecanoic acid in nanometer scale and core-shell nanocapsule structure. The thermal performance of phase change materials under the nanometer scale was enhanced.(1) We use the template method to prepare nano structure octadecanoic acid with different morphologies, without other materials, avoiding the thermal test influence of matrix, we can independently study the thermal properties of octadecanoic acid in the nanometer scale. We synthesized several different morphologies of octadecanoic acid, such as hexagonal piece, square piece, cluster, branche and nanowire, the properties of the nano octadecanoic acid were characterized by SEM, EDS, FT-IR and XRD. From the thermal results, we compared the nano octadecanoic acid to the traditional octadecanoic acid, thermal properties were changed. DSC data showed that the phase transition temperature after nanometer was slightly lower, but some were higher; Thermal conductivity data showed that the thermal conductivity was improved in nanometer scale.(2) We prepared core-shell octadecanoic acid nanocapsule which was encapsulated by silica, the nanocapsule structure can effectively solve the leakage problem when liquid-solid phase change process occurs. We use the micro emulsion method to prepare the core-shell structure, firstly, the materials were formed into oil in water microemulsion, and then PTMS was added into the microemulsion dropwisely, the hydrolysis and condensation procedures occurred on the surface of octadecanoic acid, finally octadecanoic acid was wrapped by silica, the core-shell nanocapsul was synthesized successfully. The nanocapsule was analyzed by SEM, TEM, FT-IR, XRD, and the thermal properties were tested by DSC tester, DSC results showed that melting temperature and solidification temperature of nanocapsule increased 15℃and 12℃respectively than traditional octadecanoic acid, but the thermal enthalpy didn't decreased. We study the influence to the nanocapsule of different experimental conditions, different core-shell ratio, different hydrolysis and condensation time, different temperature, which obtains the best experimental conditions.