2
Read the following statements
A. The permeability coefficient increases as the pressure increases
B. Diffusion coefficient increases with an increase in temperature
C. Highly polar polymers are excellent water vapour barriers
D. Non-polar polymers have excellent water barrier properties
Choose the correct answer from the options given below:
EXPLANATION
Food Packaging Materials
- 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
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