Tangent delta

Quinone diimines are capable of reacting rapidly with radicals formed during intensive mixing. The product, a polymer-bound PPD moiety, provides a polar functionality which is capable of improving polymer-filler interactions. In general the improvements can result in modest reductions in tangent delta (rolling resistance) and modest improvements in abrasion resistance. 

The dielectric loss data calculated from the I(discharge) currents according to equation 5.19 show a clear maximum due to the glass-rubber transition for the experiments at 29°C and 20°C. These data are plotted in Figure 5.7 as a function of the frequency together with the AC data. The results of both measuring systems can be fitted reasonably. The measured dielectric loss and tangent delta maximum temperatures are... 

Table 5.1 The dielectric loss/tangent delta maximum...

Table 5.2 The dielectric tangent delta of SSBR (vulcanised...

The results of these measurements are listed in Table 5.2 and plotted in Figure 5.8. The tangent delta maximum value due to the glass-rubber transition is clearly visible in the curves measured at 3°C, -9°C and -17°C. 

The resulting tangent delta/frequency relation of the SSBR sample at 18°C is shown in Figure 5.9. These results indicate that such a shifting possibility offers data extending over more than eleven decades of frequency while the actual measurements were performed over only four decades. 

In contrast with the dielectric constant, the tangent delta/temperature relation between 0°C and 240°C is not (detectably) influenced by these moisture concentrations. The tangent delta/temperature curves of both wet systems show, however, a clear relaxation effect with maxima between -60eC and -70°C. These effects disappear after drying i.e. they stem from the water phase. Such a low-temperature, low-frequency loss process was also detected in dynamic mechanical measurements. Banhegyi et al. reported such an effect due to absorbed water for CaC03 filled polyethylene samples [21]. 

INFLUENCE OF MOISTURE UPTAKE DURING STORAGE UNDER ATMOSPHERIC CONDITIONS ON THE TANGENT DELTA... 

The mechanical spectra of fully cured adhesive measured by shear rheometry, are shown In Figures 5 and 6. These figures Illustrate how modulus (loss and storage) and tangent delta vary with temperature and frequency. To evaluate the variation of mechanical properties with respect to percent conversion of an adhesive containing low boiling monomers, as In the case with the adhesive of this study. It was decided to assess only property/frequency response. 

Tg Is reported as tangent delta maximum from mechanical spectra. 

Figure 6 Comparison between the various thernial methods of analysis for a typical semicrystalline polymer. Notice that the beta and alpha peaks in the DMTA trace of tangent delta give much more information than the DSC. For most geometries the expansion given by TM A is also available.

Study of Foly(methyl Methacrylate) with Dynamic Mechanical Analysis by Determination of Tangent Delta... 

Results of the Data Analysis of the Tangent Delta Measuremeny of FMMA in Fig. 4.104... 

Figure 4.3 Tangent delta curve for tread compound property prediction [6].

All three systems give similar tensile strength, elongation, and hardness properties. Conventional and semi-EV systems tend to display better hysteresis (heat buildup) as measured by tangent delta and imaged fatigue resistance. 

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