Effect of biaxial drawing on morphology and properties of copolyamide nanocomposites produced by film blowing

In this work, extensional behavior in non-isothermal and isothermal conditions of copolyamide-based nanocomposites was analyzed and correlated to bubble stability in the film blowing processing of these materials. The higher values of transient extensional viscosity and 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. Oxygen barrier and mechanical properties of the films were investigated and correlated to the resulting polymer crystal structure and filler morphology. At the higher draw ratios and blow up ratios the nanocomposite specimens were present essentially in the mesomorphic β-form, nevertheless, significant improvements in barrier and mechanical properties of the hybrid films were observed, likely due to a good dispersion and orientation of the silicate platelets in the polymer matrix.

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► Higher extensional viscosity and melt strength for copolyamide nanocomposites.
► Nanoplatelets in copolyamide matrix slightly affect breaking draw ratio values.
► Silicate platelet bending and filler re-aggregation phenomena upon stretching.
► Higher stretching conditions promotes the mesomorphic β-form in all the films.