5. Implementation

5.1 Rheology

The viscosity of styrenic polymers at processing temperatures depends on their molecular structure, in particular on molecular weight and distribution, which are a function of polymerization conditions and, above all, of the plasticizer content used during polymerization. Viscosity decreases with decreasing molecular weight and increasing plasticizer content. It is easily measured by the melt-index, expressed in g/min at 200 C and measured in accordance with IS0 1133. The higher the melt-index, the more fluid the polymer.

Like most thermoplastics, styrenic polymers in the molten state exhibit non-Newtonian behavior and viscoelastic character (cf. [AM 3 620] and [AM 3 630] references [5]...