Characterization and thermophysical properties of unsaturated polyester-layered silicate nanocomposites

The thermophysical properties of unsaturated polyester (UPE) nanocomposites reinforced by organo-montmorillonite clay nanoplatelets are reported. The organo-clay nanoplatelets were sonicated in acetone for 2 hours to be dispersed in the UPE matrix. Vacuum extraction removed not only the acetone but also the styrene present in the UPE solution. The same mechanical and thermophysical properties of UPE were regained after adding the lost amount of styrene to the UPE solution. Both delaminated and intercalated clay morphologies were observed by transmission electron microscopy. It was found that the sonication process was effective to delaminate clay nanoplatelets for more homogeneous dispersion, dependent on organic chemical modifications for clay nanoplatelets. A higher storage modulus enhancement was obtained when the organo-clay nanoplatelets were delaminated and more homogeneously dispersed. The reinforcing effect of both delaminated and intercalated clay nanoplatelets was theoretically evaluated with the Halpin-Tsai equations. It was evaluated that the aspect ratio of delaminated clay nanoplatelets was approximately 150. The increase of the storage modulus below and above the glass transition temperature was achieved without reducing glass transition temperature and Izod impact strength with increasing clay content.