CPE Packaging Materials & Components 5 — Questions and Answers
Question 1: Which packaging material property is critical when designing packages for high-altitude distribution environments?
- Tensile strength
- Seal integrity under reduced external pressure (Correct answer)
- UV resistance
- Surface gloss
Correct answer: Seal integrity under reduced external pressure
At high altitude, reduced external air pressure can cause sealed flexible packages to balloon and potentially rupture weak seals.
Question 2: What is 'retort packaging' designed to withstand?
- Frozen storage at -40°F
- High-temperature sterilization (typically 121°C/250°F or above) (Correct answer)
- UV exposure for extended periods
- High-humidity tropical environments
Correct answer: High-temperature sterilization (typically 121°C/250°F or above)
Retort packaging must survive thermal processing at 121°C (250°F) or higher, used for shelf-stable food sterilization equivalent to canning.
Question 3: In injection-molded plastic packaging, what is 'sink mark' and what causes it?
- A surface depression caused by insufficient material fill during cooling (Correct answer)
- A mark left by the injection gate location
- Discoloration from excessive mold temperature
- Warpage from asymmetric cooling
Correct answer: A surface depression caused by insufficient material fill during cooling
Sink marks are depressions on the surface caused by volumetric shrinkage in thick sections where the outer skin solidifies before the interior.
Question 4: What is the key functional difference between 'peelable' and 'pierceable' lidding films used on thermoformed trays?
- Peelable films have higher oxygen barrier; pierceable films do not
- Peelable films allow consumer hand-opening; pierceable films require fork or utensil to puncture (Correct answer)
- Peelable films are aluminum-based; pierceable films are polyester-based
- Pierceable films are resealable; peelable films are not
Correct answer: Peelable films allow consumer hand-opening; pierceable films require fork or utensil to puncture
Peelable lidding is designed for easy consumer hand-opening, while pierceable lidding is intended for cooking pouches where steam venting occurs through puncture.
Question 5: What does the term 'basis weight' mean when applied to paper and paperboard?
- The weight of a single sheet
- The weight in pounds of a ream of sheets cut to the standard size for that grade (Correct answer)
- The weight per square inch of material
- The weight of a full roll on the press
Correct answer: The weight in pounds of a ream of sheets cut to the standard size for that grade
Basis weight is the weight in pounds of 500 sheets (one ream) cut to the standard reference size for that particular paper grade.
Question 6: Which test evaluates a flexible packaging film's resistance to repeated flexing, simulating distribution stresses?
- Elmendorf tear test
- Gelbo flex test (Correct answer)
- Gurley stiffness test
- Pendulum impact test
Correct answer: Gelbo flex test
The Gelbo flex test subjects films to combined twisting and compression cycles to evaluate flex crack resistance and resulting barrier property loss.
Question 7: In sustainable packaging design, what does 'downgauging' refer to?
- Switching from plastic to paper substrates
- Reducing the thickness or basis weight of packaging materials while maintaining performance (Correct answer)
- Eliminating secondary packaging layers
- Using recycled content in primary packaging
Correct answer: Reducing the thickness or basis weight of packaging materials while maintaining performance
Downgauging reduces material thickness or weight to decrease material use and cost while still meeting performance specifications.
CPE Packaging Materials & Components 5
Which packaging material property is critical when designing packages for high-altitude distribution environments?