Tensile Properties of Cold‐formable Aluminium‐Plastics Laminate Films

Abstract

AbstractThe work was based on the need to develop a horizontal form/fill/seal pouch machine to produce retortable meal‐and‐ready‐to‐eat pouches for the military. The pouch‐forming process can be considered as cold‐forming involving non‐uniform biaxial stretching of the film. Tensile properties are well‐established characteristics of films, which can be used to describe their deformation ability.An Instron Universal Testing Machine was used to measure the tensile properties of ten cold‐formable aluminium‐plastics laminate films, with structure of PET/AI/PP or OPP/AI/PP, in which the aluminium foil thickness ranged from 10 to 51 μ. The data showed that elongation of the films was not affected significantly by separation speed. All the films failed at or very close to maximum peaks of the load‐elongation curves. Because of the orientation of the OPP layer, the tensile properties were found to depend on whether the films containing OPP were stretched in the machine direction or in the transverse direction. The aluminium layer was the most critical factor in determining the maximum elongation of the entire laminate film, and the elongation‐at‐break of the films ranged from 25 to 45%. The load‐at‐break values of the films increased linearly with increasing aluminium thickness, and values of the tensile properties versus aluminium thickness curves extrapolated at zero thickness provided a measure of the strength of the plastic layers in the lamination. There was synergism between the laminate layers allowing the aluminium layer to stretch more than the normal elongation.