Dynamic mechanical loss

Figure 7.4 Dynamic mechanical loss curves of polyesters prepared from PET modified with 3 mol% of CHDM (relative to PCT)...

Figure 6. Dynamical mechanical loss at 110 Hz for three PPO-PS mixtures as a function of temperature...

The dynamic mechanical loss tangent, tan <5, determined [13] for PET at four different frequencies, over a range of temperature between - 150 and 75 °C is shown in Fig. 11. 

From the behaviour of the BXT copolymers, the authors concluded that j3 blocks of seven to nine units are required for a BPA-PC-like j3 transition. Such a conclusion can be questioned since the tan 8 curves for B3T and B5T copolymers show a clear shoulder in the - 100 °C region, suggesting that in these copolymers the motions involved in the ft transition of BPA-PC can occur within the B blocks. The larger tan 8 peak around - 25 to 0 °C reflects the motions encountered in the alternate BT copolymer. However, it is worth noting that a deeper analysis of the whole set of results would require consideration of the dynamic mechanical loss compliance, /", as done in Sects. 6, 7 and 8. 

Fig. 53 Dynamic mechanical loss spectrum of BPA-PC. The solid line is the result of simulation using the phenyl ring motion characteristics (from [34])...

It appears that it is mostly the high-temperature part of the fi transition which is suppressed, leading to a downward shift of the peak maximum. As presented in Fig. 71, the strength of the fi relaxation, expressed by the area under the dynamic mechanical loss, peak, Rsec, decreases much more rapidly with increasing the AP concentration that it should according to a dilution effect. It is worth pointing out that a similar behaviour has been reported, a long time ago, on the same system [53] and is encountered in BPA-PC-antiplasticiser mixtures, irrespective of the specific nature of the antiplasticiser small molecule [16,17,53,54]. 

To illustrate the transitions occurring in the glassy state, the temperature dependencies of the dynamic mechanical loss tangent at 1 Hz of the DGEBA/HMDA, DGEBA/tetramethylene diamine and DEBA/dodecamethyl-ene diamine systems [65] are shown in Fig. 93. They clearly exhibit two transitions ... 

It is interesting to compare the dynamic mechanical loss compliance, /", of a MGIM copolymer of intermediate glutarimide content with that of a CMIM copolymer of similar composition, taking as a reference the PMMA response weighted by the %(mol/mol) of MMA in each considered copolymer. Thus, the temperature dependencies of /"(MGIM21) and 0.79 / (PMMA)... 

Concerning the f) transition of MGIMx copolymers (described in [1] Sect. 8.3), the dynamic mechanical loss, E", at 1 Hz is shown in Fig. 53. The investigations lead to the following main conclusions ... 

Fig. 53 Temperature dependence of the dynamic mechanical loss modulus, El, at 1 Hz, for PMMA and various MGIMx copolymers (From [52])...

Before considering the various mechanical properties, it is important to notice that the transition of these copolyamides, as shown by the dynamic mechanical loss modulus, E", in Figs. 84 and 85 for the xTyl -y and MTyIi y series, respectively, occurs at quite low temperatures. Indeed, for the first series the ft peak maximum occurs at - 60 °C at 1 Hz, and at - 110 °C for the second series. From this point of view, these copolyamides look more like BPA-PC (Sect. 4) than PMMA (Sect. 3). 

The dynamic mechanical loss spectrum of polystyrene, in common with the spectra of most polymers, shows a small number of discrete loss peaks which are best resolved by a low-frequency test, preferably at or below 1 Hz. Figure... 

Atack D (1981) Dynamic mechanical loss properties of wood. Philosophical Magazine A, 43(3) 619-25... 

Analyses of (PP/PE)-g-IA by the method of dynamic mechanical losses using the inverted torsion pendulum tester (47) show a lack of compatibility between amorphous phases of the polymeric components. 

Samples of polymethacrylates mixed with PVC in ratios of 100 0, 5 95, 10 90, 15 85, 0 100 were examined on the Rheovibron. The relationships between the tangent of the dynamic mechanical loss angle and the temperature are shown in Figs. 5 and 6. From these data, the glass transition temperature regions were established for... 

Fig, 5. Temperature dependence of angle of dynamic-mechanical loss for PVC-(PMMA+PBMA) 30/70 system. 

Fig. 6. Angle of dynamic-mechanical loss vs. temperature for PVC-MMA/BMA 30/70 system.

Similar procedures have been used by several workers (Halasa et al., 1982) to hydrogenate poly(l,4-butadiene-co-1,2-butadiene) diblocks (Halasa, 1985) and poly(l,4-butadiene-co-l,4-isoprene-co-1,4-butadiene) triblocks. Hydrogenation of these diblock and triblock copolymers forms thermoplastic elastomers with crystalline and amorphous segments. All these materials exhibit crystallinity, glass transition, solubility, and dynamic mechanical loss spectra different from those of their unsaturated counterparts. 

Styrene Single dynamic mechanical loss peak... 

Figure 4. Dielectric loss factor e at lOHz and dynamic mechanical loss modulus E at 1 Hz as functions of temperature for polycarbonate. (Adapted from ref. 34 and 35.)...

The concepts derived from physical aging and water ingression into polymers will be used to interpret the dynamic mechanical results for the poly(amide-imide) in the present study. It is beneficial to examine the effects of water and aging simultaneously in order to decouple their influence on the dynamic mechanical loss properties of the polymer. 

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