Preparation of Rigid Bentonite/PAM Nanocomposites by an Adiabatic Process: Influence of Load Content and Nano-structure on Mechanical Properties and Glass Transition Temperature

Abstract

Polyacrylamide bentonite nanocomposites were prepared in an aqueous suspension. The suspension was obtained by mixing the dispersion of both bentonite and acrylamide in bidistilled water, and followed by adiabatic processes of radical polymerization with ammonium persulfate as initiator. The percentage by weight of bleaching clay (BC) was fixed at 1%, 3% and 5%. Thin films were obtained using an evaporation solution (thickness of films was in the range 100–300 μm). X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and micro-indentation technique were used to characterize the obtained films. SEM micrographs show an exfoliated structure in polymer composites that originates from the nature and method of polymerization used (a radical adiabatic polymerization under neutral condition). DSC measurements reveal that the glass transition temperature increases with percentage in weight of BC. The mechanical tests confirm that the obtained materials have high values of hardness. We conclude that our materials have a special nano-structure that determines the good mechanical properties. It is also shown that average micro-hardness decreases with increasing amount of BC which implies some changes from the initial structure.