Thermal performance improvement of plant-based fabrics via pyrophyllite impregnation: an environmentally friendly approach to geocomposite insulation materials

Pyrophyllite is a mineral known for its chemical inertness, thermal stability and low thermal conductivity. Such properties are making it a suitable material for modern and advanced insulation technologies. The study evaluates the potential of pyrophyllite-rich natural resources for industrial usage in heat-resistant, eco-friendly and sustainable geocomposite insulation panels when combined with plant-based fabrics such as cotton, jute and linen.

The samples obtained from the Pütürge district of Malatya, where the majority of pyrophyllite deposits in Türkiye are located, were characterized mineralogically and geochemically in order to evaluate their suitability for industrial purposes and geocomposite production. Pyrophyllite-rich sample powders were micronized to improve bonding between mineral particles and fabric fibers, while plant-based fabrics were mercerized with sodium hydroxide for better surface reactivity. Mercerized fabrics were impregnated with a binder solution which includes the micronized powder and sodium silicate and later subjected to heat treatment to provide stability. Thermogravimetric (TGA) and Differential Scanning Calorimetry (DSC) analyses on both untreated and impregnated fabrics revealed their mass-loss characteristics, thermal decomposition behavior and their flame-retardant potential.

The results indicate that impregnating the plant-based fabrics with pyrophyllite significantly increases the thermal performance. Among these fabrics, the best improvement in thermal mass retention is observed in cotton, followed by jute and linen. Jute fabrics exhibit the highest degree of thermal endurance, maintaining structural stability up to approximately 600 °C. The positive change in heat resistance for cotton and linen is relatively weaker, but all mineral-impregnated fabrics develop a char layer after combustion, with residual masses of 33-43% for jute, 17-20% for cotton, and 15-18% for linen. This mineral-based barrier is essential for sustainable thermal insulation, as it reduces heat transfer and supports the long-term integrity of the resulting geocomposites. In conclusion, the results demonstrate that pyrophyllite-impregnated plant-based fabrics, especially jute, are highly suitable for production of environmentally friendly, sustainable, thermally resistant and flame-retardant geocomposites for insulation purposes.