The preparation and characterization of thermal expansion capric acid microcapsules for controlling temperature

Although the microencapsulation technology can encapsulate the organic phase change materials (PCMs), the vaporized PCMs break the microencapsulation at a high temperature and can be ignited before the polymer materials, which contributes to the fire spread. The thermal expansion capric acid (CA) microcapsules (TCAMs) were successfully fabricated based on polyurethane/polyacrylate in this study, which can prevent the capric acid from escaping at a high temperature and increase the temperature control ability. The results indicated that the diameter of TCAMs after heat treatment increases from 100 μm to 400 μm. The vaporized capric acid broke the microcapsule between 220 °C and 280 °C. Although the phase change behavior of TCAMs was similar to that of normal microcapsules, the residues of TCAMs after heat treatment were much higher. The result from small room model test also proved that the TCAMs have more robust and stable temperature control ability. Because the capric acid containing high content of C and H contributed to the combustion of composite, the normal microcapsules increased the heat release rate of the composite to 366.27 kW/m 2 , while the heat release rate of the composite containing TCAMs was 332.88 kW/m 2 because the thermal expansion shell prevented liquid and vaporized CA from leaking. • The thermal expansion capric acid microcapsules (TCAMs) is prepared. • The TCAMs can prevent the CA from escaping at a high temperature. • The TCAMs expand to 400 μm after heat treatment. • The TCAMs reduce the fire risk of composite. • The TCAMs have robust and stable temperature control ability.