Microstructure and barrier properties of PHBV/organoclays bionanocomposites
Résumé
The impact of organomodified montmorillonite on morphology, thermal and barrier properties of PHBV-based nanocomposites prepared by melt intercalation was investigated. XRD analyses and TEM observations have shown the presence of aggregated and intercalated structures with individual nanoclay platelets and a significant orientation of nanoclays into the nanocomposites. No nucleating effect induced by nanoclays was detected in DSC measurements, which indicates that the crystalline phase of the PHBV copolymer was not impacted. The improvement of barrier properties to gas and water was found to be dependent not only on the dispersion and orientation of nanoclays but also the nature of permeated molecules, the quality of the matrix/nanoclays interface and degradation effects induced during melting process. A competition between kinetic and thermodynamic contributions of the permeation process was highlighted. A dependence of the water diffusion coefficient with water concentration was observed as a result of water plasticization effect.