Modulus, lossy

Figure 4. Values of lossy modulus, E". Data from references 1, 5, and 8. The data for PEMA was obtained from 3G" at 1 Hz and converted to 110 Hz. The PEMA homopolymer is seen to have a very high E" value over a broad temperature range brought about by the strong secondary transition. With no common comonomer the loss peaks and also tan S peaks (Figure 5) of the IPN s tend to be bimodal.

Figure 10. Idealized lossy modulus behavior as a function of polymer I/polymer II incompatibility. With increasing incompatibility, the loss peak first broadens, then forms two distinct loss peaks as the components separate into two distinct phases.

The equations which describe the lossy modulus behavior product and maximum temperature bandwidth for random copolymers of P(EMA-co-EA) and a maximum E"maX of PnBA. The product of T. /2N and E"max(dy/cm2 x 10" ), simi-... 

This model of lossy modulus behavior is thus strongly influenced by the exceptionally large secondary transition of PEMA,... 

The empirical temperature bandwidth constant (K), a measure of extensional damping effectiveness, is strongly affected by polymer secondary loss mechanisms. Polymers such as PMMA and PEMA form very effective damping materials because they possess broad temperature span lossy modulus curves. 

The elastic moduli of a lossy material can also be represented as complex quantities [3,4]. The complex dynamic modulus M is related to the corresponding complex sound speed c as follows [3],... 

The elastic moduli of a lossy material are also complex quantities. The relation between the complex shear wave speed and the complex shear modulus is... 

This method can be used for materials which are too soft or too lossy to support resonance vibrations alone. By making measurements at various vibration modes (up to 20 nodes along the sample length), a considerable frequency range can be obtained with a single sample. The choice of the thickness ratio for the two layers depends on th ir modulus and loss tangent ratios. Interest in such measurements stems not only from the opportunity of deriving viscoelastic data but also from the... 

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