The choice of barrier structure will depend on several considerations:

• Required shelf life - 6 months, 1 year, more than 1 year
• Type of product being packaged - is it more or less oxygen sensitive
• The conditions under which the product is stored and transported
• Bag filling machine conditions such as time, temperature, type of sterilizing medium used

This graph illustrates the typical oxygen and moisture transmission rate properties of various classes of barrier structures. All of these structures comprise an oxygen barrier "core" in addition to one or more polyethylene layers.

Note:

• "Clear" refers to a structure that is transparent or translucent
• "Double barrier" refers to a bag structure containing two barrier components rather than just one.

Additional performance attributes in addition to oxygen and moisture barrier when choosing the right structure for an end-use application include:

• Flex-crack resistance
• Puncture and tear resistance
• Degree of clarity
• Tensile strength
• Oil and grease resistance
• Cost

Structures based on biaxially-oriented nylon have only moderate oxygen barrier, but have good flex-crack resistance and oil/grease resistance.

Structures containing metallized polyester on the other hand have significantly better oxygen barrier, but are somewhat less flex-crack resistant and are not transparent. The best oxygen and moisture barrier is provided by foil.

DuPont Liquid Packaging Systems assists each customer in developing the right barrier film to protect your product. For the right barrier film for your product, a DLPS sales representative would be happy to assess and determine your particular needs.