Structure-Property Relationships of Nanocomposites Based on Polylactide and Layered Double Hydroxides - Comparison of MgAl and NiAl LDH as Nanofiller

Nanocomposites based on poly(l-lactide) (PLA) and organically modified Ni/Al layered double hydroxides (NiAl/LDHs) are prepared by melt blending and investigated by a combination of size exclusion chromatography, differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), wide-angle X-ray scattering, and broadband dielectric spectroscopy. A detailed comparison to the behavior of the corresponding MgAl/LDH-PLA nanocomposites is made. SAXS investigations show that the morphology of the NiAl/LDH-PLA nanocomposites is more intercalated compared to the MgAl/LDH based PLA nanocomposite, which is more exfoliated. The DSC investigation gives a different dependence of the degree of crystallization on the concentration of LDH for NiAl/LDH-PLA than for MgAl/LDH-PLA nanocomposite system. These differences are discussed taking the differences of the morphologies of both systems into account. Broadband dielectric spectroscopy reveals information about the molecular dynamics where essential differences are observed for all relaxation processes taking place in both systems which were related to the different morphologies.