Natural microtubule encapsulated phase change material with high thermal energy storage capacity

A novel microtubule encapsulated phase change material (MTPCM) for thermal energy storage was successfully prepared by embedding lauric acid (LA) in kapok fiber (KF) microtubules. Using a facile vacuum impregnation method, the obtained MTPCM achieved an unprecedented high thermal energy storage capacity up to 87.5% that of pristine LA. This capacity is much higher than previously reported values which are generally '60%. The high encapsulation ratio and thermal energy storage capacity can be ascribed to the unique thin wall and large hollow structure of KF. Moreover, the LA was confined inside the KF hollow fibers, leaving the interfiber space and surface free of LA. The MTPCM exhibited robust cycling stability and reusability without significant thermal storage capacity deterioration or phase change temperature variation after 2000 continuous heating/cooling cycles. In addition, the MTPCM showed enhanced thermoregulatory capacity compared with that of KF Therefore, considering the nature microtubule is green, renewable, low cost, hollow structure with giant adsorption capacity, and the easily prepared MTPCM exhibits suitable phase change temperature, high latent heat, as well as excellent thermal reliability and thermoregulating capacity, the nature microtubule based MTPCM will have great potential from the viewpoint of renewable and sustainable development. (C) 2019 Elsevier Ltd. All rights reserved.