Resistance of plastics to chemicals – how to choose the right material for the contents?

Basic plastics – PE, PP, PET

Polyethylene (PE) remains the most popular material thanks to excellent resistance to most acids and bases. HDPE shows better chemical resistance than LDPE, especially in contact with oils and fats. A weakness of PE is its susceptibility to organic solvents – toluene, xylene, or acetone cause swelling and degradation. In 2025, PE availability remains high, with short lead times (7–14 days). Polypropylene (PP) offers the broadest spectrum of chemical resistance among popular plastics. It performs well against acids, bases, and most solvents. Its exceptional thermal resistance (up to 120°C) makes it ideal for products requiring sterilization. PP is widely available in the European market, though prices rose by 15% compared to 2024.

Table 1: Chemical resistance of basic plastics

*PET undergoes hydrolysis in an alkaline environment.

Specialist plastics – PVC, PS, PA

PVC, despite environmental controversies, is still used thanks to excellent resistance to oils and fats. Its transparency and rigidity make it popular in pharmaceutical blisters. Availability of PVC in 2025 is limited by EU regulations, with lead times extended to 4–6 weeks.

Table 2: Resistance of specialist plastics

PS (polystyrene) shows limited resistance, particularly to aromatic solvents. PA (polyamide) offers excellent resistance to hydrocarbons but weakens with acids. Availability in 2025 varies – PS is readily available, while PA requires imports from Asia (6–8 weeks).

Practical guidelines for material selection

Cosmetics with high concentrations of essential oils require PP or PETG. PE may degrade under prolonged contact with certain fragrance components. For products with pH > 8 (e.g., hair dyes), avoid PET due to hydrolysis risk. PP or PE are safe alternatives. Products containing solvents (nail polishes, removers) require glass or special copolymers. Standard plastics degrade or allow volatile components to permeate. For fruit acids >10% concentration, PP or HDPE with an EVOH barrier is recommended. PET may develop microcracks with long-term contact.

Resistance is not everything – how to approach material selection?

Choosing the right plastic is a balance between chemical resistance, availability, and cost. In 2025, flexibility is key – having approved alternatives for each material. PP remains the most universal choice for a wide range of products. The growing popularity of recycled plastics requires additional compatibility testing. Investing in stability tests early in product development helps avoid costly complaints. Working with suppliers offering local warehouses minimizes production downtime risks in uncertain times.