Modell zur beschreibung der viskoelastischen eigenschaften von synthetischen fasern

The evaluation of the viscoelastic response of synthetic fibres from stress-relaxation data over a wide range of time at different strain rates is very time-consuming. Therefore, mathematical models are used to describe the viscoelastic response. The characteristic of synthetic fibres is that already at very low deformation rates like an elongation < 1% a nonlinear viscoelasticity has to be considered. Based on the analytical representation of isothermal viscoelastic behaviour by Boltzmann a new model making an assertion to the nonlinear viscoelasticity is proposed. Applying this model, the calculated values of moduli and relaxation tensions of the fibres Nomex® and PEEK are in good agreement with the experimental values.     

Solution properties of comb‐like polymers consisting of dimethylsiloxane monomer units

A series of comb‐like polymers consisting of dimethylsiloxane monomer units and differing by side‐chain length have been studied in hexane solution using analytical ultracentrifugation, translational diffusion and viscometry. Analysis of the hydrodynamic parameters and their molar mass dependences based on the Fixman–Stockmayer theory or wormlike spherocylinder model shows that with side chain lengthening, the Kuhn segment length A of the polymers under study increases from the value of A for linear polydimethylsiloxane to values typical for semi‐rigid chain polymers A = 8–10 nm. © 2016 Society of Chemical Industry