Gas & Vapour Permeability in Packaging: Water Vapour Transmission Rate (WVTR), Oxygen Permeability & Detector Film

• Mass Transport through Food Packaging Polymers:
• Pressure dependence: Gas permeability ($P = D \times S$) through polymeric barriers increases as pressure differential increases due to higher gas solubility and matrix plasticization.
• Temperature dependence: Gas diffusion coefficient increases exponentially with temperature according to Arrhenius kinetics ($D = D_0 e^{-E_d/RT}$).
• Polymer polarity: Non-polar hydrocarbon polymers (Polyethylene - LDPE/HDPE, Polypropylene) lack hydrophilic groups, exhibiting excellent water vapor barrier properties (low WVTR).
• Statement C is false: Polar polymers (EVOH, cellophane, polyamide) absorb moisture and possess poor water barrier properties.
• Conclusion: A, B, D only (Option 2).

Correct option: (2) A.B,D only

• Water Vapour Transmission Rate (WVTR) of Packaging Polymers:
• Polyamide (Nylon 6) contains recurring polar hydrophilic amide groups ($-\text{CONH}-$) that form hydrogen bonds with water molecules, resulting in high moisture permeation ($\gt 150 - 200\text{ g/(m}^2\cdot\text{day)}$).
• In contrast, non-polar polyolefins (LDPE) provide low WVTR ($10 - 15\text{ g/(m}^2\cdot\text{day)}$).
• Conclusion: Nylon 6 (Option 1).

Correct option: (1) Nylon 6

• Detector Film Method for Packaging Permeability:
• Analytical Principle:
• Utilized to measure the gas and vapor permeability of polymeric barrier films.
• Uses a sensitive reagent-coated detector film that changes spectral absorbance as permeating gas diffuses through the test substrate.
• Conclusion: Permeability of film (Option 3).

Correct option: (3) Permeability of film