Effect of different clay treatment on morphology and mechanical properties of PVC-clay nanocomposites

Three kinds of polyvinyl chloride (PVC)/montmorillonite (MMT) nanocomposites were prepared by melt blending of PVC with Na+-MMT and two organically modified MMTs. The nanostructure and relaxation behavior of the PVC/MMT nanocomposites were studied by wide angle X-ray diffraction (WAXD), transmission electron microscopy (TEM) and dynamic mechanical thermal analysis (DMTA). It was found that partially intercalated and disordered structure formed in PVC/Na+-MMT nanocomposites, while partially intercalated and partially exfoliated structures coexisted in the two PVC/organic MMT nanocomposites. The stiffness and impact strength of the three kinds of nanocomposites were improved simultaneously within 0.5-3 wt% MMT content with respect to that of bulk PVC. Below 5 wt% MMT content, the three kinds of nanocomposites retain good optical clarity. In addition, the addition of organic MMT should be kept below 5 wt% in order to enhance the mechanical properties and improve the processing stability of the PVC/MMT nanocomposites. (C) 2002 Elsevier Science Ltd. All rights reserved.