Dynamic storage modulus

Dynamic mechanical analysis curve Graphical representation of the data collected by a dynamic mechanical analyser, where the dynamic loss modulus, dynamic storage modulus and tan 5 are plotted as a function of temperature (scanning mode) or time (isothermal mode). 

Figure 1 Plots of dynamic storage modulus against temperature at 3.5 Hz [33]. EPO (-), EPl (— —), EP2...

Fig. 24. Schematic of the evolution of the dynamic storage modulus, G, with extent of reaction, p, at four different frequencies...

Dynamic mechanical testers apply a small sinusoidal stress or strain to a small sample of the polymer to be examined and measure resonant frequency and damping versus temperature and forced frequency. Instrument software computes dynamic storage modulus (G ), dynamic loss modulus (G") and tan delta or damping factor. Measurements over a wide range of frequency and temperature provide a fingerprint of the polymer with sensitivity highly superior to DSC. 

In analysis of the dynamic storage modulus, toluene diamine-cured resins schibited the highest modulus in standard-cured san les, vAiereas all the HT-cured resins showed nearly similar elastic moduli. 

Figure 4. The variation of tli dynamic storage modulus (C) with oscillation...

Figure 6. The variation of the dynamic storage modulus (G ) with oscillation frequency at 0 C for UHMWPE pseudo-gel (4% w/w) first run , second run V, third run A, fourth run.

Figure 8. The variation of dynamic storage modulus (G ) of UHMWPE pseudo-gel (3% w/w) with ten perature at w=100 sec" heating cycle, o cooling cycle.

The static modulus and dynamic storage modulus were investigated for some open-celled PE foams by static compression tests and dynamic viscoelastic measurements in compression mode. Experimental data were compared with theoretical predictions. 8 refs. 

The dynamic storage modulus of closed-cell PE foams was investigated by dynamic viscoelastic measurement in the compression mode. It was found that dynamic modulus correlated with compression hardness and that the resistance against pressure inside the cells had no effect upon static modulus or dynamic storage modulus. 8 refs. 

Fig. 9. The effect of magnesium hydroxide filler type on the dynamic storage modulus G of polypropylene (PP) at 200 °C (strain amplitude 10%, filler level 60% by weight). Magnesium hydroxide fillers differed in origin particle size and treatment. Mean particle size (pm) type A ( ), 7.7 type B (+), 0.9 type C ( ), 4.0 type D ( ), 0.53 type E, stearate-coated version of type A, (X), 3.7 unfilled PP (O) [36]...

Fig. 12. The frequency dependence of dynamic storage modulus G at 200 °C for calcium carbonate filled polypropylenes (mean particle size 0.15 pm).Filler loading wt%, (o) 0 (6) 10 (o) 20 (9) 30 [47]...

Fig. 21 Plots of log dynamic storage modulus versus strain amplitude for ACM/silica hybrid nanocomposites at different silica concentrations at 50°C...

It turns out that stress relaxation following a simple shear deformation is seldom employed experimentally. A more common technique is to measure the steady state response to small sinusoidal deformations as a function of angular frequency to. The dynamic storage modulus G (to) and loss modulus G"(to) in small sinusoidal deformations are related to G(t) ... 

A schematic of the system is illustrated in Figure 1. For dynamic frequency sweeps (refer to Figure 2), the polymer is strained sinusoidally and the stress is measured as a function of the frequency. The strain amplitude is kept small enough to evoke only a linear response. The advantage of this test is that it separates the moduli into an elastic one, the dynamic storage modulus (G ) and into a viscous one, the dynamic loss modulus (G"). From these measurements one can determine fundamental properties such as ... 

Fig. 4 Temperature dependence of the dynamic storage modulus E and loss modulus E" for CELL/PACMO composites. (Reproduced from [72])...

With physical aging at 140 °C in nitrogen/dark atmosphere, the dynamic storage modulus is very sensitive to aging time. The modulus increased from 13 GPa (10 minutes-aged) to 18 GPa for samples aged up to 105 minutes at 140 °C (see Fig. 16). These results agree with observations made in the stress relaxation experi-... 

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