Flexible composite phase change films enhanced by hectorite and graphene nanoplates

Abstract

Phase change materials (PCMs) are essential for improving energy efficiency in thermal management systems, yet their widespread adoption is hindered by challenges such as flammability and low thermal conductivity. This thesis explores the integration of hectorite and graphene nanoplatelets (GNP) into flexible PCMs to address these limitations and expand their use in various applications. The incorporation of hectorite significantly bolsters the mechanical and fire retardant properties of PCMs. Experiments reveal that flexible PCMs with 15% hectorite content demonstrate an increase in tensile strength to 16.84 MPa and a reduction in fracture strain to 3.27%, which is a marked improvement over PCMs without hectorite, which exhibit a tensile strength of 9.56 MPa and a fracture strain of 3.92%. Furthermore, the addition of GNP has profoundly enhanced the thermal conductivity and phase change efficiency of polyethylene glycol/cellulose nanofiber (PEG/CNF) composite films. The introduction of 5% GNP elevates the thermal conductivity coefficient to 3.22 W/mK, and with 15% GNP, it further escalates to 12.2 W/mK, a substantial rise from the base composite's conductivity of 0.184 W/mK. This enhancement is critical for applications requiring swift and efficient heat management. Practical tests of these enhanced PCMs in building management, wearable technology, and electronics illustrate their versatility. In building applications, these materials stabilize indoor temperatures, effectively reducing energy demands for heating and cooling systems. For wearable technologies, the PCMs help maintain stable skin temperatures, enhancing user comfort and safety. In electronics, these materials adeptly manage heat, preventing overheating and extending device longevity. This research highlights the successful integration of hectorite and GNP in overcoming the traditional limitations of PCMs, significantly enhancing their functionality and safety. The findings bridge the gap between laboratory research and practical implementation, suggesting that the advanced PCM composites have the potential to revolutionize thermal management practices across diverse sectors.