Heat energy storage systems were fabricated with the impregnation method using MgO and Mg(OH)₂ as supporting materials and polyethylene glycol (PEG-6000) as the functional phase. MgO and Mg(OH)₂ were synthesized from the salt Mg(NO₃)·6H₂O by performing hydrothermal reactions with various precipitating agents. The precipitating agents were NaOH, KOH, NH₃, NH₃ with pamoic acid (PA), or (NH₄)₂CO₃. The result shows that the selection of the precipitating agent has a significant impact on the crystallite structure, size, and shape of the final products. Of the precipitating agents tested, only NaOH and NH₃ with PA produce single-phase Mg(OH)₂ as the as-synthesized product. Pore size distribution analyses revealed that the surfaces of the as-synthesized MgO have a slit-like pore structure with a broad-type pore size distribution, whereas the as-synthesized Mg(OH)₂ has a mesoporous structure with a narrow pore size distribution. This structure enhances the latent heat of the phase change material (PCM) as well as super cooling mitigation. The PEG/Mg(OH)₂ PCM also exhibits reproducible behavior over a large number of thermal cycles. Both MgO and Mg(OH)₂ matrices prevent the leakage of liquid PEG during the phase transition in phase change materials (PCMs). However, MgO/PEG has a low impregnation ratio and efficiency, with a low thermal storage capability. This is due to the large pore diameter, which does not allow MgO to retain a larger amount of PEG. The latent heat values of PEG-1000/PEG-6000 blends with MgO and Mg(OH)₂ were also determined with a view to extending the application of the PCMs to energy storage over wider temperature ranges.

A polyurethane (PU) is a multifunctional polymer prepared by using more than two types of monomers. The unique properties of PU come from monomers, thus broadening the applicability of PU in many different sectors. The properties can be further improved by using many nanoparticles. Different metal oxides as nanoparticles are also widely used in PU materials. ZnO is a widely used inorganic metal oxide nanoparticle for improving polymer properties. In this review article, the techniques to prepare a PU/ZnO composite are reviewed; the key protective properties, such as adhesive strength and self-healing, and applications of PU/ZnO composites are also highlighted. This review also highlights the PU/ZnO composite’s current challenges and future prospects, which will help to broaden the composite practical application by preparing environmentally friendly composites.

Tertiary oil recovery, commonly known as enhanced oil recovery (EOR), is performed when secondary recovery is no longer economically viable. Polymer flooding is one of the EOR methods that improves the viscosity of injected water and boosts oil recovery. Xanthan gum is a relatively cheap biopolymer and is suitable for oil recovery at limited temperatures and salinities. This work aims to modify xanthan gum to improve its viscosity for high-temperature and high-salinity reservoirs. The xanthan gum was reacted with acrylic acid in the presence of a catalyst in order to form xanthan acrylate. The chemical structure of the xanthan acrylate was verified by FT-IR and NMR analysis. The discovery hybrid rheometer (DHR) confirmed that the viscosity of the modified xanthan gum was improved at elevated temperatures, which was reflected in the core flood experiment. Two core flooding experiments were conducted using six-inch sandstone core plugs and Arabian light crude oil. The first formulation—the xanthan gum with 3% NaCl solution—recovered 14% of the residual oil from the core. In contrast, the modified xanthan gum with 3% NaCl solution recovered about 19% of the residual oil, which was 5% higher than the original xanthan gum. The xanthan gum acrylate is therefore more effective at boosting tertiary oil recovery in the sandstone core.