Properties of Scots pine wood impregnated with capric acid for potential energy saving building material

Scots pine sapwood (Pinus sylvestris L.) was impregnated with different concentrations of capric acid (CA) (20, 40, 60 and 80%) as phase change material (PCM). The hygroscopic, mechanical properties and thermal energy storage (TES) characteristics of the CA-impregnated wood were studied. The morphology, crystalline properties, phase change properties and thermo-regulative performance of CA-impregnated wood were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermogravimetry (TGA), differential scanning calorimetry (DSC) and thermal performance analysis. CA-impregnated wood demonstrated an excellent performance of storing and releasing heat during phase change process, confirmed by DSC and FTIR analysis after an accelerated thermal cycling test. In addition, the accelerated thermal cycling test results indicated that CA-impregnated wood showed good thermal reliability and CA did not leach from the wood after the thermal cycling. Wood impregnated with CA solution of 80% concentration reduced the maximum temperature by 4.04 degrees C at the end of the heating period while it increased the minimum temperature by 2.83 degrees C at the end of the cooling period. The performance of storing and releasing heat during phase change process of CA impregnated Scots pine proves that it can be used as a thermal regulating building material to reduce energy consumption and cost caused by day and night temperature fluctuations.