Plasticisation

Plasticisation, in materials science, refers to the process of making a material more plastic or flexible, typically by adding a plasticizer. It can also describe the softening of a polymer by solvent exposure or heat. A plasticizer is a low‑molecular‑weight compound that interposes between polymer chains, increasing free volume and reducing intermolecular forces. The result is a lower glass transition temperature and modulus, with higher ductility and processability. Plasticisation can be reversible (solvent-induced swelling) or permanent (chemical interaction or degradation altering chain mobility).

External plasticisers are miscible with the polymer but not covalently bonded; internal plasticisation involves covalent attachments to the polymer backbone that confer flexible segments. Common plasticisers for polymers include phthalates, adipates, citrates, and sebacates, though health and environmental concerns have driven the development of non‑phthalate alternatives. In PVC, for example, plasticisation greatly increases flexibility but can also reduce barrier properties and cause migration over time.

In cement technology, plasticisers or superplasticisers are admixtures that disperse cement particles, allowing higher workability at lower water contents. They are essential for modern concrete such as high-performance formulations.

Practical considerations include compatibility between plasticiser and polymer, potential migration or blooming to the surface, effects on mechanical properties, aging, and environmental or health impacts of the plasticiser.