Case Study of Fungal Mycelium/Eicosane Composite as an Energy Storage Additive for Gypsum Plaster in a Model Experiment

The adsorption of organic phase-change materials (PCMs) on the supporting fibers has been demonstrated as a versatile and efficient method for developing stable composites with thermoregulatory properties. These composites are promising as energy saving additives in dry building mixtures. However, developing composite fibers with an optimal morphology to maximize their content and thermoregulation in the desired material is still a significant challenge. In this study, we have created stable composite fibers by depositing the organic PCM eicosane on fungal mycelial biopolymer fibers. The resulting composite has a fibrous structure with a lateral size of 1.5–2 μm and a latent heat capacity of 70 J/g. It was mixed with dry gypsum powder at a weight ratio of 30%. Electron microscopy analysis showed a uniform distribution of fibers throughout the hardened gypsum layer. The DSC analysis revealed that the inclusion of the composite to the plaster significantly improved its thermal properties, allowing for the storage and release of latent heat with heat capacity of 30 J/g. Temperature measurements within the hardened plaster showed that the presence of thermoregulating fibers slowed down the heating process between 32–38°C and cooling between 38–35°C, corresponding to the melting and solidification of eicosane in the composite structure. Finally, model experiments with a testing chamber demonstrated that the accumulation and release of the thermal energy resulted in the decrease in internal air temperature during the heating cycle and in the increase of internal air temperature during the cooling cycle, respectively.