Thermally stable micro-sized silica-modified wool powder from one-step alkaline treatment

Across the world, waste wool generated in farms and textile industries is often discarded without any utilisation. Low thermal stability of wool, i.e., melting of alpha-helix near 160 degrees C and degradation around 185-210 degrees C, further limits its use where a higher temperature is required. In the past, wool powder with slightly enhanced thermo-stability has been prepared using ionic liquids (from those containing toxic imidazole and pyridine), though the search for finding a sustainable and economic alternative is still ongoing. The current study proposes a conversion method of wool waste into highly thermo-stable micro-sized silica-modified powder through controlled disintegration of wool using a single-step chemical treatment. This study for the first time, reports an optimised method of wool powder preparation using sodium silicate solution while also maintains comparatively lower chemical to wool ratio among the previous reports. The properties of chemically prepared powder were thoroughly compared with powder of similar size prepared using mechanical milling. The chemical modification of wool showed improvement in its crystalline structure through alpha-helix to beta-sheet transition and reduction in the interlayer spacing. The known high thermal stability of silicate groups significantly enhanced the thermal stability of the modified wool, given only 12-38% weight loss was recorded even at 600 degrees C. Overall, this research reveals an innovative method of transforming waste wool into thermally stable micro-sized powder for potential wider applications, such as high temperature extrusion, 3D printing, thermo-resistive coating, insulation in automotive and construction industries. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study proposes a method of converting waste wool into thermally stable micro-sized silica-modified powder through controlled chemical treatment. The chemically prepared powder showed significant improvement in thermal stability and crystalline structure compared to mechanically prepared powder. This research reveals an innovative method for transforming waste wool with potential applications in various industries.