pps proceeding - Abstract Preview
pps proceeding
Symposium: S15 - Rheology and rheometry
Oral Presentation
 
 

Determination of the viscoelastic Poisson’s ratio of polymers using DMA in torsional and axial direction

Arnold Gunther (1)*, Troiss Alexander (2), Klutz Alexander (2)

(1) Anton Paar Germany GmbH - Ostfildern - Germany, (2) Anton Paar GmbH - Graz - Austria

The lateral contraction of a material when stressing the material in axial direction is described by the Poisson’s ratio [1]. In case of viscoelastic materials, like polymers, this parameter is a function of time (frequency) and temperature and important for e.g. structural mechanics simulations [1,2]. Several methods are described to determine the viscoelastic Poisson’s ratio. The methods can be classified in direct methods which directly measure the change of the dimensions of the specimen and indirect methods from which the measurement of two moduli like shear modulus and Young’s modulus seems to be the most effective [3]. The contribution highlights a testing procedure using a combined torsional-axial dynamic mechanical analyzer (MCR 702 MultiDrive) and clamping fixtures for cylindrical as well as rectangular specimens in order to determine the viscoelastic Poisson’s ratio of different solid polymers. Using a linear and a rotational measuring drive in one instrument enables the determination of complex Young’s modulus |E*| as well as the complex shear modulus |G*| with a single sample in a continuous measurement run. Consecutive frequency sweeps at different temperatures in both, torsion and tension deformation modes were performed to obtain the viscoelastic Poisson’s ratio, following the protocol proposed by Tschoegl et al. [2].The suitability of the method is further examined and discussed by comparing the results with literature data. [1] Pandini, S., Pegoretti, A.: Time and temperature effects on Poisson’s ratio of poly(butylene terephthalate). Polymer Letters 5 (2011) 685-697. [2] Tschoegl, N.W. et al.: Poisson’s Ratio in linear viscoelasticity – a critical review. Mechanics of Time-Dependent Materials 6 (2002) 3-51. [3] Pritz, T.: Measurement methods of complex Poisson’s ratio of viscoelastic materials. Applied Acoustics 60 (2000) 279-292.