Water removal in Polymer − Ca2+-Montmorillonite (Ca2+-Mon) composites prepared in colloidal System: DSC studies in low temperature range

Abstract

Dehydration within low temperature range (30 °C − 100 °C) of Ca2+−Montmorillonite or Ca2+−Mon had caused water removal, where its endothermic from DSC curve reveals the heat of fusion H is about 336.96 J/g. Comparable endothermic within similar temperature range detected in PE-Mon, DPNR-Mon, ENR50-Mon and pPVC-Mon composite profile also indicates the present of interlayer water from Ca2+−Mon particles in the composites. The reduced H about 13% (DPNR-Mon), 32% (PE-Mon), 61% (ENR-50) and 70% (pPVC-Mon) suggests that water removal had occurred during composite fabrication in colloidal systems. XRD analysis however demonstrates that the clay interlayer structure in PE-Mon and DPNR-Mon remain unaffected with similar d001 = 1.46 nm as in pristine Ca2+−Mon. Structural effect from water removal can be seen in the case of ENR50-Mon and pPVC-Mon composites, where the reduced gallery height gives d001 = 1.29 nm and 1.34 nm respectively. Peak intensity behaviors as shown by hydroxyl ((∂HOH) and (νOH)) and silicate (Si-O) bands in FTIR spectra help to explain the observations, particularly the appearance of Si-O band (1017 cm−1) that proves the occurrence of water removal inside the clay composites.