Preparation and properties of multifunctional thermochromic energy-storage wood materials

Abstract

To develop a smart multifunctional wood material, thermochromic energy-storage microcapsules were incorporated into coatings while painting medium density fiberboard (MDF). The morphologies, chemical structures, and thermal properties of the microcapsules were characterized. The coating performance, including the thickness, wearability, and adhesion were investigated. The thermochromic and energy-storage properties of the coated MDF were evaluated using chroma meter and differential scanning calorimeter, respectively. Four different microcapsule concentrations were determined to analyze the effect of the concentration on performance of the multifunctional material. The microcapsules demonstrated a sensitive color change phenomenon and possessed a latent heat of over 90 J/g. The color of the surface of the coated MDF could repeatedly change between blue and light brown within a temperature range of 20–39 °C, presenting a “color hysteresis” phenomenon over a heating (decolorization) and cooling (coloration) cycle. Meanwhile, the coated MDF could be considered an energy-storage material with a phase-change temperature range of 12–38 °C. The multifunctional MDF could be suitable for use as a decorative and thermo-regulating material. The concentration of the microcapsules obviously reduced the wearability of the coatings, but had no significant effect on their adhesion. The total color contrast of the MDF increased from 31.26 to 57.03 as the microcapsule concentration increased from 2.5 to 10 % (of the coating weight), while a linear positive correlation was verified between the enthalpy of the coating and the concentration. The microcapsule concentration could potentially be used to adjust the performance of the multifunctional MDF.