Melt rheology of polylactide/montmorillonite nanocomposites

In this article, the linear and nonlinear shear rheological behaviors of polylactide (PLA)/clay (organophilic-montmorillonite) nanocomposites (PLACNs) were investigated by an Advanced Rheology Expanded System rheometer. The nanocomposites were prepared by master batch method using a twin-screw extruder with poly(epsilon-caprolactone) (PCL) as a compatibilizer. The presence of org-MMT leads to obvious pseudo-solid-like behaviors of nanocomposite melts. The behaviors caused by the formation of a percolating network derived from the reciprocity among the strong related sheet particles. Therefore, the storage moduli, loss moduli, and dynamic viscosities of PLACNs show a monotonic increase with MMT content. Nonterminal behaviors exists in PLACNs nanocomposites. Besides the PLACNs melts show a greater shear thinning tendency than pure PLA melt because of the preferential orientation of the MMT layers. Therefore, PLACNs have higher moduli but better processibility compared with pure PLA. (c) 2007 Wiley Periodicals, Inc.