Phase Transitions and Structure Of Crystalline Polymers

Crystalline polymers build up complex structural entities, which blend amorphous and crystalline domains at a very small scale (≈ 10 nm). The coexistence of domains, which are of molecular, dimensions stems from the fact that the chains tend to fold upon crystallisation: this chain folding is a characteristic feature of polymers, and creates an organisational scale which is unique to polymers. It induces a small scale subdivision of the polymer space, and makes it necessary to describe the structure of crystalline polymers at three different length scales: at the level of the unit-cell (characteristic dimensions: fractions of nanometers), at that of the chainfolded lamellae (thickness: 10 nm, lateral dimensions: several μm) and finally, spherulites (from μm to mm).