Plasticiser — Frequently Asked Questions

Ortho-phthalates, now largely restricted in consumer use; terephthalates such as DOTP; adipates such as DOA for low-temperature work; trimellitates such as TOTM for high temperature; citrates and DINCH as non-phthalate options; and bio-based esters including epoxidised soybean oil. Each family trades efficiency, permanence, temperature range and regulatory status differently.

By working out which property governs. If the article must stay flexible in the cold, an adipate. If it must survive continuous heat, a trimellitate. If it must be food contact or a toy, a non-phthalate with the appropriate approval. If cost dominates and none of those constraints apply, a general-purpose ester. Most commercial compounds blend two or more to balance the trade-offs.

Because the plasticiser leaves. It is held physically rather than chemically bonded, so it gradually migrates to the surface, evaporates or is extracted by contact with oils, fats or solvents. As the plasticiser content falls the polymer chains can no longer slide past one another, and the article becomes stiff and eventually brittle.

The film that forms on vehicle glass as plasticiser evaporates from dashboard and trim materials and condenses on the cold windscreen. It is both a visibility problem and evidence that the plasticiser is leaving the polymer. Low-volatility high molecular weight plasticisers are specified in automotive interiors specifically to prevent it.