What are the differences in chemical resistance between polyethylene and polypropylene?

Polyethylene (PE) and polypropylene (PP) are two of the most commonly used thermoplastic polymers in industrial and consumer applications. While both share some similarities, their chemical resistance properties differ significantly due to variations in their molecular structures.

Polyethylene exhibits excellent resistance to acids, alkalis, and most solvents, making it ideal for containers storing harsh chemicals. However, it is susceptible to oxidizing agents and certain hydrocarbons. In contrast, polypropylene offers superior resistance to a broader range of chemicals, including many organic solvents and acids, but performs poorly against chlorinated solvents and strong oxidizers.

The higher melting point of polypropylene (160-170°C) compared to polyethylene (115-135°C) also contributes to its enhanced chemical resistance in high-temperature environments. For applications requiring prolonged exposure to aggressive chemicals, polypropylene is often the preferred choice, while polyethylene remains cost-effective for less demanding conditions.

Understanding these differences is crucial for selecting the right material for specific industrial, medical, or packaging applications where chemical compatibility is a critical factor.