Temperature sweep experiment

Mechanical Properties. Dynamic mechanical properties were determined both in torsion and tension. For torsional modulus measurements, a rectangular sample with dimensions of 45 by 12.5 mm was cut from the extruded sheet. Then the sample was mounted on the Rheometrics Mechanical Spectrometer (RMS 800) using the solid fixtures. The frequency of oscillation was 10 rad/sec and the strain was 0.1% for most samples. The auto tension mode was used to keep a small amount of tension on the sample during heating. In the temperature sweep experiments the temperature was raised at a rate of 5°C to 8°C per minute until the modulus of a given sample dropped remarkably. The elastic component of the torsional modulus, G, of the samples was measured as a function of temperature. For the dynamic tensile modulus measurements a Rheometrics Solid Analyzer (RSA II) was used. The frequency used was 10 Hz and the strain was 0.5 % for all tests. 

Steady-state shear stress-shear rate measurements are by far the most commonly used method in many industrial laboratories. Basically, the dispersion is stored at various temperatures and the yield value and plastic viscosity r are measured at various intervals of time. Any flocculation in the formulation should be accompanied by an increase in tr and r. One rapid technique for studying the effect of temperature changes on the flocculation of a formulation is to perform temperature sweep experiments, running the samples from perhaps 5 to 50 °C. Any trend in the variation of tr and r with temperature can quickly provide an indication of the temperature range at which a dispersion will remain stable, since during that temperature range cr and r will remain constant. 

The features of the standard SCR reaction (Rl) system (feed devoid of NO2) are first highlighted. A typical temperature sweep experiment (Fig. 11.4a) shows the changes in the effluent concentrations as a function of temperature when a dry feed containing equal concentrations of NO and NH3 (NO = NH3 = 500 ppm) in excess O2 was passed over an Fe-ZSM-5 catalyst. Negligible NO conversions (<20 %) were observed up to 250 °C. At a temperature of about 300 °C there is a nonlinear increase in NO conversion, which approaches 91 % at 450 °C. The NH3... 

Figure 8.12 Complex viscosity of the EVA/LDPE polymer blend with nanoclay and /or FR (ATH) as a function of (a) frequency and (b) temperature. For frequency-sweep experiments, the temperature is 140 °C and the stain at 1% for temperature-sweep experiments, the frequency is 10 rad/s and the strain at 10%.

Fig. 20.7 Variations of lq l with temperature during isochronal dynamic temperature sweep experiments at a = 0.1 rad/s for (a) open circle) PyHQ12 and open triangle) PSHQ12, and for (b) open circle) PyHQ12/Cloisite SOB nanocomposite, open triangle) PyHQ12/Cloisite 15A nanocomposite, and open square) PSHQ12/Cloisite SOB nanocomposite (Reprinted with permission from Huang and Han (2006a). Copyright 2006 American Chemical Society)...

Figure 8.9 Temperature dependence of G for a highly asymmetric SIS triblock copolymer specimen having a 0.18 weight fraction of PS block (Vector 4111, Dexco Polymers Company), which was annealed at 140 °C for 2 days prior to the isochronal dynamic temperature sweep experiments at an angular frequency of 0.01 rad/s in the heating process. (Reprinted from Sakamoto et al., Macromolecules 30 1621. Copyright 1997, with permission from the American Chemical Society.)...

Figure 8.15 Log G versus log G" plots for a highly asymmetric solvent-cast SIS triblock copolymer (SIS-110) specimen during heating at various temperatures (°C) (O) 140, (A) 151, ( ) 155, (V) 160, (O) 162, (O) 164, ( ) 166, (A) 168, ( ) 170, (T) 172, ( ) 174, m 180, (C) 190, (A) 200, (H) 202, (V) 204, ( ) 206, (O) 208, (A) 210, (11) 212, and (V) 214. Prior to the rheological measurements, the specimen was annealed at 110 °C for 3 days. The inset describes the temperature dependence of G obtained from the isochronal dynamic temperature sweep experiment at < = 0.01 rad/s during heating. (Reprinted from Choi et al.. Macromolecules 36 7707. Copyright 2(X)3, with permission from the American Chemical Society.)...

In this section, we present the effect of thermal history on the oscillatory shear rheometry of block copolymers. We will show that the occurrence of a minimum in G in the isochronal dynamic temperature sweep experiment does not necessarily signify OOT for highly asymmetric block copolymers instead, it sometimes reflects imperfect bcc spheres, as determined by SAXS and TEM, due to an insufficient annealing of a specimen. Here, we will show that a minimum in G, observed for an unannealed specimen in the isochronal dynamic temperature sweep experiment, may disappear completely when the specimen is annealed for a sufficiently long time at an elevated temperature below the TmoT of highly symmetric SI diblock copolymer. 

Figure 8.23 gives the tempa ature dependence of G during the isochronal dynamic temperature sweep experiments at > = 0.01 rad/s in the heating process for highly asymmetric SI diblock copolymer SI-7/29 (M = 3.6 x 10", — 1.03, —... 

Figure 8.32 Temperature dependence of G obtained from isochronal dynamic temperature sweep experiments at = 0.1 rad/s for ( ) dPS-fc/ock-PnPMA-H with = 5.33 x 10, (O) dPS-fc/ocUP PMA-L with = 4.5 x 10, (A) dPS-WocUPnPMA-BH composed of 55 wt % dPS-Wocyfe-P PMA-H and 45 wt % dPS-Nocfe-PwPMA-L, ( ) dPS-Wocfe-PnPMA-BM composed of 50 wt % dPS-Wock-P PMA-H and 50 wt % dPS-Wucfc-PnPMA-L, and (V) dPS-l Zock-PnPMA-BL composed of 45 wt % dPS-block-PnPMA-H and 55 wt % dPS-Wock-PnPMA-L. (Reprinted from Ryu et al., Macromolecules 36 2894. Copyright 2003, with permission from the American Chemical Society.)...

Temperature Dependence of Dynamic Moduli of TPU during Isochronal Dynamic Temperature Sweep Experiment... 

Figure 12.48 compares logG versus logG" plots of S1-14/3-OH with those of 95/5 (SI-14/3-OH)/Cloisite 30B nanocomposite at various temperatures, in which the insets show the results of the isochronal dynamic temperature sweep experiments at... 

Figure 12.52 describes the temperature dependence of dynamic storage modulus G during the isochronal dynamic temperature sweep experiment at an angular frequency (ty) of 0.1 rad/s for PS, PS-t-COONa, (PS-t-COONa)/Cloisite 20A nanocomoposite, and (PS-t-COONa)/Cloisite 30B nanocomposite. The following observations are worth noting in Figure 12.52. Not only is the magnitude of G for PS-t-COONa much larger than that for neat PS, but also the values of G for PS-t-COONa decrease slowly, as compared with the values of G for neat PS, with increasing temperature. We attribute this observation to the formation of ionic clusters in PS-t-COONa. It has been reported...

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