Thermoforming 2014

To extend the shelf life of sensitive pharmaceutical or food products without preservatives, modified atmosphere in packaging (MAP) will be applied. Therefore, the gas tightness of these packagings is most important for maintenance of this atmosphere.

The gas tightness is defined by the quality of seal seams and the permeability of material. The permeability is a standard disclosure in data sheets of materials and can be used in the evaluation of permeability of pouch packaging for example. In the area of thermoformed packaging the evaluation of permeability is more difficult because of the large elongation of material under high temperature and velocity. The inhomogeneous wall thickness distribution prevents a simple conclusion to the resulting permeability of the whole packaging.

In the field of industrial packaging development and material specification an approximately proportional relationship between permeability and material thickness will be expected independent from the stretching history. However, numerous academic publications show that there is an influence of some material parameters on permeability and their dependence on stretching parameters (e.g. temperature). But investigations on the relevance of these influences in relation to the thickness in thermoforming are missing.

Within this project, samples will be homogeneously stretched under defined temperature, velocity and deformation parameters. These samples will be measured in permeability. With these results it will be possible to describe the relevance and influence of individual parameters on the permeability. Based on the results the material specification and selection can be more focused and in addition, material efficiency can be improved.