One of the more popular materials used in the packaging industry today is polypropylene. The properties of this material will change depending on the molecular structure chosen (homopolymer, copolymer, impact modified, etc..) and the additives used during the polymerization process for polypropylene (anti-oxidants, performance additives, and nucleating agents). That being said the following list provides some general guidelines regarding polypropylene packaging.
Advantages of Polypropylene
- Cost competitive when material properties such as clarity, stiffness, toughness and impact strength are considered.
- Grades available to handle hot fill, and microwavable applications.
- Grades available that can provide high heat deflection properties that are required during retort applications.
- Grades available to handle frozen food to microwave applications.
- Crystalline structure lends well to resistance to fats and oils that can cause ESC.
- Provides very good moisture barrier properties.
- Excellent chemical resistance.
- Low taste and odor concerns. FDA grades available.
Disadvantages of Polypropylene
- High specific heat means longer heating and cooling times, i.e. long cycle times.
- High shrinkage rate creates trimming issues.
- Narrow melting point, yields smaller processing temperature window.