Shear storage

FIGURE 5.17 Temperature versus G —the shear storage modulus at a frequency of 1.6 Hz for diblock copolymer poly(ethylene propylene)-poly(ethylethylene) (PEP-PEE). The order-disorder transition (ODT) calculated to be 291°C 1°C. (From Rosedale, J.H. and Bates, F.S., Macromolecules, 23, 2329, 1990. With permission of American Chemical Society.)... 

Fig. 10. Effect of field intensity on the ER effect in a polymer gel. AG (O) and AG" ( ) represent increments in shear storage and loss moduli of the gel induced by applied electric fields. The dotted line displays the relationship AG = kE2 (k constant, E field intensity)...

Fig. 11. Effect of dielectric constant of dispersed particle on the ER effect in a polymer gel. The increment in shear storage modulus induced by an ac electric field of 0.4 kV/mm is plotted as a function of the real part of the dielectric constant of the particle...

Fig. 14. Effect of the volume fraction of ethylene glycol on the temperature dependence of the shear storage and toss moduli of poly(2-hydroxyethyl methacrylate) 1 = 0.15 2 = 0.33 3 = 0.47 4 = 0.58 5 = 0.76 6 = 0.84...

Fig. 21. Effect of the volume fraction vd of ethylene glycol on the decrease in the shear storage modulus in the transition from the glassy to rubberlike state. Gg is the modulus of the glassy state (140 K), G represents the boundary between the /8d and a dispersions (cf. Fig. 14), Ge is the modulus in the rubberlike state...

The shear storage modulus of the network is proportionally related to the force constant K. Thus, G is also related to the particle volume fraction via the fractal dimension D) of the network. 

In practice, the fractal dunensions of fat crystal networks, are measured by determining the shear storage modulus, G, of the fat crystal networks within the LVR measured by small deformation rheology. The fractal dimension of the fat crystal network may be calculated from the slope of the curve as > = 3-1/slope of logarithm of G at different SFC, O. 

Figure 6. Shear storage modulus versus temperature for a series of 25/75 SIM PUR/PAc IPNs obtained with various amounts of stannous octoate ( ) 1.0% ( ) 0.5% ( ) 0.35% (A) 0.25% ( ) 0.1%.

Figure 1. Shear storage modulus vs. cure time for 10 phr filler loading.

Fractal Dimension Evaluation using Small Deformation Rheology (Dr) To determine for a particular system by rheological methods, the shear storage modulus (G ) must be measured at different solids volume fractions. The solids volume fraction, which is equal to the SEC/100, is varied by diluting the fat with an inert solvent that will not cocrystallize, or otherwise alter the behavior of the system. Canola oil has been used as a suitable AMF diluent for these purposes. A log-log plot of G versus <1) yields a slope p from which Dj can be... 

Figure 1. Dynamic shear storage modulus and loss tangent as a function of temperature for PS-0.02MAA-Na plasticized to varying degrees by diethylbenzene (DEB) curves 1, "5 2, 80 3, 84 4, 88 5, 92 6, 100 wt % polymer(adapted from ref. 25).

Figure 28. Temperature dependence of the mechanical shear storage...

The dynamic shear storage modulus (G1) and loss modulus (G") were measured from -150° to 50°C using the forced torsion fixture on a Rheometric Mechanical Spectrometer (RMS). When the storage modulus dropped below 10 Pa. this fixture became insensitive. For moduli less than 10 Pa, the parallel plate fixture with serrated disks was used. The parallel plate fixture was used to extend the dynamic mechanical measurements to high temperatures. Degradation above about 250°C dictated this temperature as an upper limit for RMS measurements. Further discussion of equations and use of these fixtures are given elsewhere (2,8). 

Figure 4. The high-temperature shear storage and loss moduli of Halthane 73-14 and 73-19 adhesives are controlled by the presence or absence of the cross-linking agent quadrol in the hard segments. In the linear urethane (73-14), viscous flow follows the melting of the hard segments, whereas in the cross-linked urethane (73-19), the modulus drops only when the polymer begins to degrade.

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