Tan S vs. temperature

FIGURE 28.20 Curves of tan S vs temperature for rubber and carbon nanotubes (CNTs)/rubber nanocomposite. (From Lopez-Manebado, M.A. et al., J. Appl. Polym. Sci., 92, 3394, 2004.)... 

Our study of pure polyurethane, PU/E, and PU/E/UPE IPN elastomers, has shown that IPNs have very broad glass transitions (broad tan S vs. temperature peak) centered around room temperature. The pure polyurethanes have a relatively high and sharp T well below RT. Fillers such as mica and graphite have not shown any significant effect on tan 6 height or temperature range. 

Figure 1. Dynamic mechanical spectrum (left log E (Pa), right tan S vs temperature (°C)) of the thermal cure of PMDA-ODA polyamic acid film at a.) 5 °C/min. and b.) 0.5 °C/min.

Fig. 33. Multifrequency modulus and tan S vs temperature plots. To convert N/m to psi, multiply by 1.45x10. ...

FIG. 87 Dynamic Yoimg s modulus vs temperature for PE (Rigidex 140-60) samples at different draw ratios (measured at 20 Hz, experimental points shown for Cor = 35). (b) tan S vs temperature for PE (Rigidex 140-60) samples at different draw ratios. Draw ratio curve 1,11 curve 2,15 curve 3, 28 curve 4, 35. (From Ref. 117.)... 

Figure 6.19 shows the tan S vs. temperature at 1 Hz frequency for the SPTES polymers. The maximum damping peaks of SPTES-100 appear at 202 and 238°C. 

Plots of loss modulus or tan S vs temperature for pol5miers give peaks at energy absorbing transitions, such as the glass transition and low temperature secondary transitions (Fig. 17). Such plots are useful for characterizing polymers and products made from them. 

Figure 10. DMTA (tan S vs. temperature) of PEBA Samples F, G, and H with a constant PTMG block length and PA12 block lengths ranging from 1500 to 4000 g/mole...

Figure 7.1 6 Complex shear modulus and tan 5 vs. temperature for an IPN containing inverted coreshell particles of SAN/poly ethyl hexyl methacyriate (El-Aasser, M. S. et a/., Colloids Surf A, 153, 241, 1999) Elsevier.

Figure 8.19. Tan 6 vs. temperature for several IPN s. The loss tangent of semicompatible compositions remains high over a broad temperature range. (Huelck et al, 1972.)...

The damping factor, tan 6 vs. temperature for the pseudo and full IPN s showed two peaks corresponding to the Tg s of the polyurethane and the acrylic copol3nner networks. The size of the damping peaks changed systematically with concentration of the alloys, i.e., decreased with the component concentration. 

Tan delta vs. temperature at lOx frequency intervals from 0.1 rad/s(B)to 100 rad/s (A) via time-temperature superposition for a general purpose tape adhesive based on styrenic block copolymers... 

Subsequently, several research teams became interested in studying the damping characteristics of IPN s. Wong and Williams characterized the tan d vs temperature behavior of polyurethane-epoxy semi-IPN s, noting one very broad peak ranging from 273 to 363 K for the 50/50 composition. Klempner and co-workers also studied the polyurethane/epoxy system, but prepared foams by a one-shot method, producing SIN s. Using an impedance tube method of measurement, enhanced sound absorption was found. 

Figure 4.1 Variation of physical properties vs temperature, used to determine the glass transition (a) volume (V) or enthalpy (H) (b) expansion coefficient (a) or heat capacity (cp) (c) storage modulus (E ) (d) dissipation modulus (E") and dumping factor (tan 8) (e) real part of the complex dielectric permittivity (s ) (f) imaginary part of the complex dielectric permittivity (e").

Figure 2. Mechanical loss tangent (tan 5) and elastic storage modulus at 102 c.p.s. and spin-lattice relaxation time (20) vs. temperature for poly (4-methyl-l-pentene) crystallized from dilute solution...

Pig. 17. L< arithmic decrement (related to tan S and loss modulus) vs temperature for a fluorocarbon dibenzoxazole (174). After drying up to 200°C, the experiment was conducted at 200 —180 200°C AT/At = 1.5°C/min in a helium atmosphere. The Tg gives a sharp damping peak, whereas the secondary glassy state transitions, Tsec, are very broad. 

The torsion pendulum determinations were made at low frequency ( lHz) while the duration of the impact strength measurements is on the order of 1 msec. To correct for this frequency difference, we used the WLF equation (9) and found that the 10°C (1 Hz) tan 8 information should approximately correspond to the impact measurements taken at room temperature. In Figure 1, we plot the impact strengths vs. tan 8 (10°C). A single linear correlation does not exist, but the tan 8 values predict that the S sample would have a higher impact strength than the B/S sample and that the B sample, at the other extreme, would have a lower impact strength than the S/B5 specimen. Most models would favor... 

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