Keywords: solid state NMR, polymer nanocomposites, flame retardancy, clay nanodispersion, polylactide, PLA, heat release rate, cone calorimetry, oxygen consumption, nanotechnology
PLA nanocomposites: quantification of clay nanodispersion and reaction to fire
In this work, the morphology of polylactide (PLA)/clay nanocomposite is quantitatively characterised by a novel solid state NMR method. Depending on the preparation conditions (low or high shear stress), about half of the available polymer/clay interfacial area is formed and the degree of homogeneity characterising the distribution of this interfacial area is about 40% at high shear stress. On the contrary at low shear stress, montmorillonite (MMT) platelets are evenly dispersed in PLA associated with an available polymer/clay interfacial area close to one and high degree of homogeneity (81%). The presence of clay in PLA (exfoliated morphology) leads to a significant decrease of peak of heat release rate measured by cone calorimetry by oxygen consumption.