The directional dependence of properties of a molded part is called anisotropy.
During processing (injection molding) the macromolecules are aligned in the direction of flow.
This results in different strengths depending on the direction.
In general, the strengths are higher in the direction of flow than at right angles to it.
Therefore, in material data sheets, information is usually given in the longitudinal and transverse directions.
Anisotropy is particularly pronounced in fibre-reinforced plastics.