Our Own Comparative Trials

Motivated by the above related circumstances, we set out to compare all currently available viscoelastics on the German market using Advanced Rheometric Expansion System (Fig. 31 ARES) and RMS 800 (Rheometric Scientific Inc., Piscata-way, USA) as our measuring systems with regard to their physicochemical pro- 

The shear moduli, G, the elasticity modulus and G , the viscosity modulus, were determined. The elasticity modulus is defined as the relationship of elastic pressure (in phase) to the applied force and is dependent on the ability of a substance to store energy elastically. It represents a measure of the number of interactions in a specific system. The value of the elasticity modulus G is proportional to the 

The viscosity is a function of the applied stress and is named dynamic viscosity q and complex viscosity 

As to the prevailing measurement conditions, the following becomes obvious room temperature was 23°C, duration of measure in ARES totaled 10 minutes per preparation, not exceeded in any measurement. Measurements were taken beginning at the high frequencies, down to the low frequencies. 

The test for dynamic frequency-dependency of complex viscosity q was used as the measuring method for each substance. Relaxation time was calculated from G to G above the intersection point, and the zero shear viscosity was mathematically derived by means of the so-called Ellis-fit (Fig. 32). The viscosity model, according to Ellis allows the calculation of zero shear viscosity using the following formula (compare Fig. 32)  

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