A MODEL FOR THE DESCRIPTION OF THE VISCOE LASTIC PROPERTIES OF SYNTHETIC-FIBERS

The evaluation of the viscoelastic response of synthetic fibres from s tress-relaxation data over a wide range of time at different strain ra tes is very time-consuming. Therefore, mathematical models are used to describe the viscoelastic response. The characteristic of synthetic f ibres is that already at very low deformation rates like an elongation <1% a nonlinear viscoelasticity has to be considered. Based on the an alytical representation of isothermal viscoelastic behaviour by Boltzm ann a new model making an assertion to the nonlinear viscoelasticity i s proposed. Applying this model, the calculated values of moduli and r elaxation tensions of the fibres Nomex(R) and PEEK are in good agreeme nt with the experimental values.