Rheological and thermal properties of polylactide/organic montmorillonite nanocomposites

Polylactide/organic montmorillonite (PLA/OMMT) nanocomposites were prepared by melt-compounding technique. Dynamic and steady rheological properties, as well as dynamic mechanical and thermal stability of the nanocomposites were evaluated using various characterization tools. It was found that the rheological behaviors of nanocomposites were related with both temperatures and OMMT loadings. At low OMMT loadings, the steady-shear viscosities and the complex viscosities showed a Newtonian plateau in low frequency region or low shear rate region. At high OMMT loadings, strong shear-thinning behaviors were observed in the full range of frequencies or shear rates. The complex viscosities and the storage modulus gradually decreased in the full frequency region with increasing temperature. The results demonstrated that rheology of PLA/OMMT nanocomposites was mainly sensitive to OMMT loadings. The relaxation time spectrum indicated that the relaxation of the PLA macromolecular chains was strongly confined by the layers of OMMT. The mechanical properties measured by dynamic mechanical analysis (DMA) and tensile test, and thermal stability of PLA/OMMT nanocomposites were improved at low OMMT loadings. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012