Mechanical and barrier properties of copolyamide based nanocomposites by film blowing

In this work, bubble stability in the film blowing processing of copolyamide-based nanocomposites, produced by melt-compounding, were correlated to their underling extensional behavior in non isothermal and isothermal conditions. The higher values of transient extensional viscosity and of melt strength of the nanocomposites, compared to the neat matrix, imply that they are able to better resist the extensional external force during bubble formation. On the other hand, the nanoparticles, being well dispersed and having good adhesion with the matrix, do not act as “defects” in the molten polymer and no significant worsening of the melt deformability is revealed. Hybrid films with different loadings of nanoclay were produced by film blowing. Oxygen barrier and mechanical properties of the films were investigated and correlated to the resulting polymer crystal structure and filler morphology. With regards to the crystalline structure, the HADS film is only characterized by the -crystal form, while all the nanocomposite specimens are present essentially in the mesomorphic beta form. Nevertheless, significant improvements in barrier and mechanical properties of the hybrid films were observed, likely due to a good dispersion and orientation (along the extrusion direction) of the silicate platelets in the polymer matrix