Nanocomposite-based polyamide 12/montmorillonite: relationships between structures and transport properties

Water transport through nanocomposite-based polyamide 12/montmorillonite was investigated by permeation kinetics. Intercalated and semi-exfoliated nanocomposite structures were studied. For low montmorillonite content (£ 5%) a decrease of water permeability was obtained for a both structures and mainly explained by an increase of the tortuosity (decrease of water diffusivity). However, this barrier effect is affected by other phenomena which depend on the structures: the plasticization phenomenon, the water solubility and the role played by the clay/polymer interface.

Two types of nanocomposite-based PA12 and montmorillonite modified C30B are prepared by melt compounding with two processing conditions and different volume fraction of C30B ranging from 0; 1.5; 3; 5 and 8%. The structure and morphology of these nanocomposites are observed by using wide-angle X-ray scattering and transmission electron microscopy. Water permeation measurement is studied from these nanocomposites. The water permeability and the diffusivities coefficients decrease with increase volume fraction of organoclay C30B into these nanocomposites. These results are conforming to Nielsen and Bharadwaj model. The same water permeability is observed for nanocomposites intercalated and semi-exfoliated having a same volume fraction of C30B. This result is not conforming to the model. However, during the water permeation water plasticize nanocomposites. Moreover, the plasticization phenomenon depends on the structures of nanocomposites intercalated or semi-exfoliated. This phenomenon is not included in the model. In the future work, this phenomenon will be studied by water sorption measurement.