What are the differences in gas permeability between PVC and polypropylene?

PVC (Polyvinyl Chloride) and polypropylene are two widely used plastics with distinct properties, including differences in gas permeability. PVC is known for its relatively low gas permeability, making it suitable for applications requiring a barrier to gases, such as packaging for food and medical supplies. Its molecular structure, which includes chlorine atoms, contributes to its tighter packing and reduced gas diffusion.

Polypropylene, on the other hand, has higher gas permeability due to its semi-crystalline structure, which allows gases to pass through more easily. This property makes it less ideal for applications requiring strict gas barriers but more suitable for breathable packaging or filtration systems.

Key factors influencing gas permeability in these materials include temperature, thickness, and the type of gas involved. For instance, oxygen permeability is typically higher in polypropylene compared to PVC, while CO₂ diffusion rates may also vary.

Understanding these differences helps industries select the right material for specific needs, balancing cost, durability, and performance in gas-sensitive environments.