How does the resistance to discoloration from tannins vary among these plastics?

Tannins, naturally occurring compounds found in plants, can cause unsightly discoloration on plastics over time. However, the resistance to this staining varies significantly among different types of plastics.

Polyethylene (PE) and polypropylene (PP) generally exhibit high resistance to tannin discoloration due to their non-polar molecular structures, which repel water-based stains. These plastics are often used in food containers and outdoor furniture where tannin exposure is likely.

Polyvinyl chloride (PVC) shows moderate resistance but may yellow over time when exposed to high tannin concentrations. Polystyrene (PS) and acrylics are more susceptible, often developing visible stains from prolonged tannin contact.

For applications requiring maximum stain resistance, engineered polymers like polycarbonate (PC) or specially treated surfaces provide superior protection against tannin discoloration. Understanding these differences helps in selecting the right plastic for tannin-rich environments.