By Bob Lebeaux, President, The Plastics Group of America
September 22, 2009
The primary shortcoming of polystyrene is a low softening temperature – it will sag and distort at about 200 degrees F, lower than the boiling point of water. Since many foods are water-based, heating to boiling or steaming will destroy the container. Worse yet, the polystyrene will partially dissolve in fatty foods, contaminating the food with plastic.
Here are two material types that can handle most microwave and heated food applications: Polythylene terephthalate (PET) and Polypropylene (PP).
PET has useful properties up to 400 degrees F, unfortunately, it is also much more expensive than polystyrene. PP doesn’t soften until about 300 degrees F, which is plenty high enough to withstand boiling water and steam. PP is both lighter in weight and lower in cost than polystyrene. And, talc can be used as a reinforcing agent to increase the stiffness of PP – when supplied as a fully formulated product, talc-filled PP is competitive in cost with polystyrene. Just some food for thought.
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