Thermophysical properties and grain size effects in Luffa Cylindrica-modified clay composites for thermal insulation

Abstract

The study explored the thermal insulation potential of composite material made from clay and Luffa cylindrica. Clay/ Luff cylindrica composite (denoted as Clay/L-C) was developed from natural resources. In the research, Luffa cylindrica particles of different grain sizes and different proportions were mixed with clay, and thermal evaluations were done with respect to thermal conductivity, thermal diffusivity, specific heat capacity, mass depletion with temperature, and microstructure. Two different mixture ratios, namely 4:1and 3:2 corresponding to 20 wt % and 40 wt % Luffa cylindrica particle, respectively, were used for Clay/ Luffa cylindrica combination. While Luffa cylindrica particle sizes varied from 600µm to 300µm and 150µm, the effects of Luffa cylindrica content and particle size on thermal properties were then examined. These novel composite materials developed in this study demonstrate motivating potential for enhanced thermal insulation when compared to unmodified clay. Improved thermal insulation performance indicated by thermal properties was observed for all the modified samples. This is on the account of reduced thermal conductivity of the modified samples. The best sample possessed thermal conductivity, thermal resistivity, thermal diffusivity, specific heat capacity, and porosity values of 0.216 W/mK, 462.90°C.cm/W, 0.123 mm/s2 1.493 MJ/m3K, and 89.3%, respectively. Results show that Luffa cylindrica fiber can be applied as an additive for effective thermal insulation. Development in this area of study is very necessary especially as the raw materials are readily available and cost-effective.