Packaging Materials & Components Flashcards

In glass container manufacturing, what is the primary purpose of annealing?

Answer: Relieving internal stresses after forming

Annealing involves controlled slow cooling of glass containers to relieve internal stresses that would otherwise cause breakage.

Which property best describes the 'coefficient of friction' (COF) in flexible packaging films?

Answer: The ratio of friction force to normal force between film surfaces

COF measures the slipperiness between film surfaces, critical for machine runnability and stacking stability of finished packages.

What is the primary advantage of using aluminum foil as a packaging barrier material?

Answer: Near-zero transmission of gases, moisture, and light

Aluminum foil at sufficient gauge provides essentially complete barriers to gases, moisture vapor, and light, the best barrier among flexible packaging materials.

In metal can manufacturing, what does 'double seam' refer to?

Answer: The interlocking fold joining lid and body ends

A double seam is formed by mechanically rolling and interlocking the can end's curl with the body flange to create a hermetic seal.

Which packaging material property is expressed as 'cc·mil/100 in²·day·atm'?

Answer: Oxygen transmission rate (OTR)

Oxygen transmission rate (OTR) is expressed in cc·mil/100 in²·day·atm, quantifying oxygen permeation through a film under standard conditions.

What is the purpose of a 'tie layer' in coextruded multilayer packaging films?

Answer: To bond incompatible polymer layers together

Tie layers use adhesive polymers (like maleic anhydride-grafted polyolefins) to bond chemically incompatible layers such as PE and EVOH.

When evaluating paperboard for folding cartons, what does 'fold crack resistance' measure?

Answer: The board's ability to fold without surface coating fracture

Fold crack resistance measures whether the surface coating and board substrate fracture or remain intact when the carton blank is scored and folded.