Chapter 26Analysis of Completely Formed, Filled, and Sealed Containers
Written in cooperation with Manfred Reidast, Remshalden, Germany
In Chapters 23 to 25 test methods were described concerning thermoforming film thickness measurements, shrinkage, gloss level, DSC, DMA, and some others. Analytical methods for completely formed containers have yet to be explained.
This chapter details the most important analysis methods for completely formed, filled, and sealed containers.1 This concerns mainly the determination of:
- Burst pressure and impermeability (which are closely connected)
- Opening force
Methods for the examination of the overall quality of the finished and closed containers are discussed, particularly, the quality of the sealing, by which the lid film is applied to the filled containers.
26.1 BURST PRESSURE AND IMPERMEABILITY
26.1.1 Vacuum
A vacuum chamber is used to determine the quality of the sealing of the lid film onto filled and closed cups or trays. Sealing quality mainly depends on:
- Sealing conditions (time, pressure, and temperature)
- Type and quality of the sealing medium of the lid film
- Type of the bottom film
The vacuum chamber is usually filled with water, so that the containers are immersed in water. Slowly a vacuum is created in the chamber. The emerging pressure difference tasks the sealed seams, and potential leakages can be discovered as air bubbles leak out of the interior of the container into the surrounding water.
The exact test conditions ...
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