Packaging Materials & Processes Flashcards

Which polymer property is most critical when selecting a film for retort packaging that must withstand 121°C sterilization?

Answer: High heat deflection temperature

High heat deflection temperature ensures the film maintains structural integrity during high-temperature retort sterilization cycles.

In blown film extrusion, the blow-up ratio (BUR) primarily affects which film property?

Answer: Transverse direction tensile strength

A higher blow-up ratio stretches the film in the transverse direction, increasing molecular orientation and tensile strength in that direction.

What is the primary function of an ethylene vinyl alcohol (EVOH) layer in a multilayer flexible packaging structure?

Answer: Oxygen barrier

EVOH provides exceptional oxygen barrier properties, preventing oxidation of oxygen-sensitive products like meat and snack foods.

Which corrugated board flute size offers the best cushioning for heavy industrial products?

Answer: A-flute

A-flute has the tallest flute height (~4.8mm), providing maximum cushioning and stacking strength for heavy industrial goods.

During thermoforming, what defect occurs when the heated sheet contacts the cold mold too quickly before fully stretching?

Answer: Webbing

Webbing occurs when excess material folds onto itself between the mold cavities because the sheet is not stretched uniformly before forming.

Which coating applied to paperboard converts it into a grease-resistant substrate suitable for fast-food containers?

Answer: Fluorochemical treatment

Fluorochemical (PFAS-type) treatments repel both oil and water, providing the grease resistance needed for direct food contact in fast-food packaging.

What is the purpose of a 'tie layer' in a coextruded multilayer film structure?

Answer: To bond incompatible resins together

Tie layers (typically maleic anhydride-grafted polyolefins) provide adhesion between incompatible resin layers such as polyolefins and EVOH.