Erasure of the processing effects in polyamide 6 based cast films by the introduction of montmorillonite: Effect on water and oxygen transport properties

In this paper the influence of montmorillonite layers and of the processing conditions on the morphology and transport properties of polyamide 6 based films was investigated. Films were prepared by cast extrusion keeping all the extrusion parameters constant except the chill-roll temperature. Two chill-roll temperatures were used: 50 °C and 125 °C. The nanoclay amount contained in the different systems was low and varied from 0 to 1 wt%. The state of dispersion of the nanoclays and the structure of the matrix crystalline phase were investigated as a function of the film processing conditions. The water sorption properties and the oxygen and water permeation were determined and a detailed analysis of the transport mechanism was proposed. For the neat PA6 films, a great dependency of the processing conditions on the morphology and the transport properties was observed. A significant improvement of barrier properties was obtained for the film elaborated with the high chill-roll temperature. For the nanocomposites, independently of the nanoclay amount and the processing conditions, the polymer matrix morphology and the barrier properties were close to each other. Moreover they were similar to those observed for the neat matrix elaborated with the high chill-roll temperature. From this result, the nanoclay can be considered as an efficient additive to make PA6 films properties much less processing dependent.