Understanding the core-shell interactions in macrocapsules of organic phase change materials and polysaccharide shell.

The main objective of this work is to prepare completely biodegradable macrocapsules containing organic phase change materials (PCMs) for thermal energy storage applications. Three different PCMs hexadecane (paraffin), butyl stearate (ester) and caprylic acid (fatty acid) were encapsulated inside barium crosslinked pectin shell using ionic gelation method. Millimeter size(≤2 mm) pectin-PCM capsules were prepared with highest encapsulation efficiency of 83.66 wt% (H5), 83.21 wt% (B5) and 84.39 wt% (C5) containing hexadecane, butyl stearate and caprylic acid respectively as core, while corresponding melting enthalpies were 184.89 kJ kg-1 (H5), 116 kJ kg-1 (B5) and 118 kJ kg-1 (C5). Pectin encapsulation improved thermal stability of PCM-capsules by 70 °C-130 °C compared to core PCMs. 25 g of H5, B5 and C5 capsules provided thermal buffering of 62 min, 50 min and 51mins respectively during discharge experiments. Thus, the prepared biodegradable pectin-PCM capsules are effective for thermal energy storage.