Crystallinity Measurement Testing
Using X-ray diffraction, the crystallinity of packaging polymers and ingredients are easily determined and the miscibility of composite materials is also evaluated.
As an example of the practical importance of knowing the percent crystallinity of polymers, a major food company recently had problems with their plastic ketchup bottles.
Some consumers noted that the ketchup bottles contained significantly less ketchup than specified on the label. The state authorities were notified and they verified that the ketchup was not up to specified levels. The ketchup bottles from this particular food company were removed from the store shelves and the company was fined.
It was later found that the plastic bottles were defective (due to a greater concentration of recyclates in the plastic) and were less crystalline that they should have been. The lower crystallinity of the bottle permitted the water in the ketchup to seep through to the outside (poor barrier resistance) and this led to the decrease in the weight of the ketchup inside the bottle.
Testing of the plastic bottles would have shown that the bottles were defective through the lower than desired percent crystallinity.
Package materials testing, as well as package evaluation and testing, are important parts of the research and development process. Testing helps ensure that new primary packaging materials and package designs are created specifically to handle real-world situations.