Water-resistant gum-based phase change composite for thermo-regulating insulation packaging

The world's current energy crisis calls for green energy solutions that can preserve energy while incorporating renewable. As such, we have developed a leakage-proof phase change material (PCM) embedded in a biopolymeric matrix as a lightweight yet strong bio-based phase change composite (PCC) for passive energy storage and insulation purposes in packaging. This bio-based composite consists of gum tragacanth (GT) biopolymer and polyethylene glycol (PEG) PCM. It is further incorporated with biochar (BC) or mineral additive, i.e., Cloisite Na⁺, to enhance its mechanical strength and thermal stability, which are among the main challenges for insulation materials. A hydrophobic layer of octadecyl isocyanate (ODI) is developed on the surface of the composite to increase its water resistance. The composite provides a hydrophobic surface with a minor water uptake capacity of 3.6 ± 0.3 % after one-week immersion in the water. It shows high latent heat storage up to 160 J g⁻¹ and a stable phase change behavior, as demonstrated by over 100 differential scanning calorimetry heating-cooling cycles. It also possesses notable compressive mechanical properties, which were improved significantly after incorporating BC and Cloisite Na+. The thermal conductivity of the composite is as low as 0.035 W m⁻¹ K⁻¹ manifesting in better thermal regulation compared with commercial polyethylene foams. This energy-positive bio-based solution combines the advantages of excellent insulation as a highly porous, lightweight, and strong composite with the latent heat and thermal inertia of PCM, making it suitable for transportation packaging of temperature-sensitive products.