Thermal properties and surface chemistry of cotton varieties mineralized with calcium carbonate polymorphs by cyclic dipping

Abstract

In this study, hydroentangled cotton nonwovens were identified as effective hosts for mineralization of calcium carbonate (CaCO₃) polymorphs to modify and improve their properties. All cotton varieties studied, including raw white cotton, scoured white cotton, and raw brown cotton, readily crystallized CaCO₃ via a simple cyclic dipping process. A combination of analyses agreed that the surface chemistry of cotton fibers influenced the formation of different CaCO₃ polymorphs. Scoured white cotton that consisted of almost pure cellulose predominantly produced the most stable calcite, whereas raw white and raw brown cottons that contain proteins facilitated the production of partial metastable vaterite. The morphology of calcite was better defined on the scoured cotton. The mineralization altered the hydrophobic surface of raw cottons to be hydrophilic, i.e., two-fold increase in moisture regain and decrease in water contact angle from 130 to 0 degrees. The mineralized cottons also exhibited improved thermal resistance, i.e., slower thermal decomposition with decreased activation energies and reduction in heat release capacity by up to 40%.