While rolls made of POM reveal a rather little running smoothness after a long static load rolls out of PEEK do not. The objective of this diploma thesis was to characterise the complex time dependent deformation behaviour of POM and PEEK rolls and to determine possible reasons for the different behaviour. For that purpose static, dynamic and combined tests were performed. Thus the differences both in the short-time and the long-time behaviour between both materials were shown and conclusions were drawn. The investigation was done applying different experimental techniques and the simulation of these experiments were performed by the FEM-Program ABAQUS. To get detailed information about the time dependence of the strain distribution in the rolls, in addition to the conventional force and displacement measurements, Full Field Strain Analysis was also performed. All results confirmed the difference between the behaviour of POM and PEEK observed in service. The results of the simulations agreed with the experimental results in the case of POM. In contrast, the results of the numerical simulations of PEEK did not adequately reflect the experimental results. Moreover, the Full Field Strain Analysis of the rolling rolls has shown an unexpected time dependent deformation behaviour for PEEK, especially at the contact layer.