Exploring Colloidal and Interfacial Phenomena in Coating Processes to Unlock the Potential of Palm Oil toward Energy...

Effective resource management and byproduct valuation are two of the main obstacles to using renewable materials in a sustainable economy. Due to production costs and resource availability, the palm oil industry, a significant source of bioenergy, struggles to grow, while byproducts including long-chain hydrocarbon byproducts are severely underutilized. In the spirit of colloid and interface, this study investigates the scientific mechanisms supporting favorable circumstances and develops scalable methods to integrate microencapsulated palm oil-derived phase change materials (PCMs) into textiles for thermal energy storage, focusing on pad-dry-cure and screen-printing processes. Three bio-based PCM microcapsules with thermal transitions (8-20 °C), latent heat (52-232 J/g), and high stability (>300 °C) were embedded into synthetic and natural fabrics. Key challenges involved managing colloidal interactions in aqueous solutions, particularly for negatively charged melamine-based microcapsules (-38 to -59 mV), which were stabilized using a dispersing agent to provide partial charge screening and ionic compatibilization, and enable ever-challenging pilot-scale process stability. Four substrates of different chemical and physical structures (cotton, pineapple-based, polyester woven, and polyester spunbond) were tested, with nonwoven polyester spunbond achieving the highest wet pick-up of 177% (vs 43% for woven polyester) due to its porous, intermingled microfiber structure that trapped microcapsules like a filter. Stable coating formulations incorporated multifunctional and protective additives for water repellency, UV protection, abrasion resistance, antibacterial efficacy (>99.90% for both the Gram-positive bacterium Staphylococcus aureus and the Gram-negative bacterium Klebsiella pneumoniae according to AATCC 100 standards), and fire retardancy (meeting UL 94:2014 (VTM-0) standard), expected to enhance the useful life of the composites. Screen printing with layered pigment and elastic pastes optimized PCM retention, enhancing tensile strength (>20-40% in warp/weft directions) without compromising abrasion resistance. Thermal testing via DSC and T-history methods confirmed storage capacity, with polyester spunbond exhibiting the highest latent heat (77.96 J/g cooling, 76.51 J/g heating). While wet pick-up directly correlated with latent heat, cooling/heating times showed weaker links to heat capacity. The study highlights the importance of colloidal stability and substrate microstructure in the development of industrial-scale high-PCM-loading coatings that can also be used on a range of substrates in sectors other than traditional textiles.