Ultramarine blue are a family of mineral pigments that are commonly dispersed in construction materials (concrete, paints, and polymers) to obtain colored materials. Two different methods for encapsulating phase change materials (PCM) in pigments have been studied to obtain PCM/pigment composites with thermal storage capacity: capillary and vacuum impregnation methods. The aim is to obtain a pigment providing thermal storage capacity to construction materials (apart from color) by an easily scalable process. The optimized vacuum impregnation process provides an hexadecane/pigment composite having a latent heat of fusion of 44 J/g (around a 20%wt. hexadecane adsorbed in the pigment) while the optimized capillary impregnation process allows the fabrication of a pigment with a latent heat of fusion of 41 J/g (around a 18%wt. hexadecane). Durability of both materials has been tested by the rmodiffrac to metric measurements indicating in both cases, slow reductions of the area intensity of the XRD signals (up to 10% and 15% after 100 cycles). The long term degradation behavior at room temperature was tested by DSC showing a reduction of a 3% of the thermal storage capability after 1000h.Considering the degradation and scalability issues, capillary impregnation seems to be the most suitable process for the mass production of pigments having high thermal storage capacity.

Ultramarine Blue, Hexadecane, Phase Change Material, Thermal Storage