What are the differences in vapor permeability between PVC and polyethylene?

The vapor permeability of plastics like PVC (polyvinyl chloride) and polyethylene is a critical factor in applications requiring moisture control, such as packaging, construction, and agriculture. PVC generally has lower vapor permeability compared to polyethylene, making it a better barrier against moisture transmission. This is due to its denser molecular structure and lower porosity.

Polyethylene, on the other hand, is more permeable to water vapor, especially in its low-density form (LDPE). High-density polyethylene (HDPE) offers slightly better resistance but still falls short of PVC's impermeability. The choice between the two depends on the specific needs of the application—PVC for strict moisture barriers and polyethylene for breathable or flexible solutions.

Understanding these differences helps industries select the right material for products like food packaging, waterproof membranes, and protective coverings.