Pseudo-solid-like

A pseudo solid-like behavior of the T2 relaxation is also observed in i) high Mn fractionated linear polydimethylsiloxanes (PDMS), ii) crosslinked PDMS networks, with a single FID and the line shape follows the Weibull function (p = 1.5)88> and iii) in uncrosslinked c/.s-polyisoprenes with Mn > 30000, when the presence of entanglements produces a transient network structure. Irradiation crosslinking of polyisoprenes having smaller Mn leads to a similar effect91 . The non-Lorentzian free-induction decay can be a consequence of a) anisotropic molecular motion or b) residual dipolar interactions in the viscoelastic state. 

Aggregation, agglomeration and flocculation are structural phenomena ranging from transient rotating doublets observed within dilute region, to a pseudo-solid-like behavior of flocculated suspensions with yield stress. Aggregation can occur... 

When NR was the rubber, a NR latex was mixed with Na-bentonite and Na-fluorohectorite, varying the concentration of clays from 1 to 2.5 phr and determining rheological properties with a coaxial cylinder viscometer. Viscosity increased with clay loading. Pseudo solid-like behaviour was observed in bentonite-filled composites at the loading of 2.5 phr, whereas a behaviour close to that of the Newtonian fluid was shown by unfilled NR. Stronger rubber bentonite interaction was revealed by the higher viscosity, the lower power-law indexes and the slope of the Kraus plot. ... 

Figure 15a illustrates the frequency dependence of tan 5 for the 1 wt% elastomeric EP random copolymer and well dispersed MCNFs nanocomposites at varying temperatures [120]. For clarity, these curves have been shifted along the x-axis. At high temperatures (i.e. in the range of 130-200 °C), the nanocomposite exhibited a pseudo-solid-like behavior as determined from the positive slopes in the low frequency regime. At 129 °C, the nanocomposite reached the critical gel state i.e. the tan 8(a) curve exhibited a zero-slope plateau in the low firequency regime. 

The terminal regions slope of the master curves for G and G" are presented in Table 3.7. The slope of and in the terminal region of the master curves of PLA matrix was 1.85 and 1, respectively, and these values are in the range expected for polydisperse polymers. On the other hand, the slopes of G and G" were considerably lower for all PLACNs compared to those of pure PLA. In fact, for PLACNs with high C18MMT content, G becomes nearly independent at low atut and exceeds G", characteristic of materials exhibiting a pseudo-solid-like behaviour. 

When the clay content exceeded 1 wt.%, not only the classical power laws for the frequency dependence of G and G" were deeply modified, particularly in the case of G, but the moduli increased dramatically at low frequency. This behaviour is characteristic of a pseudo-solid-like response of the material. The... 

Prior to gelation, two types of radicals with solid- and liquid-like mobility are present they are possibly located in microgels (solid-like mobility) and in monomers (liquid-like mobility). The concentration of free radicals increases continuously, so that the pseudo steady-state assumption cannot be applied to model the reaction kinetics. 

Figure 15.2 2H NMR relaxation function obtained in a PDMS model network in the relaxed state, showing the two components the fast relaxing component (the curve with alternatively long and short dashes) is pseudo-solid and belongs to elastic chains (which have restricted motions), the slowly relaxing, exponential component (dashed line), is liquid-like and belongs to dangling chains. The total signal (black points) is a superposition of both contributions, which gives the fraction of dangling chains...

Polyester BB1 was run twice in steady mode at 290°C (Figure 10), and shows that the orientational effect of the first run has a drastic effect on steady shear viscosity. In the first run the log viscosity vs. log shear rate had a slope of -0.92 (solid like behaviour, yield stress), but in the second run a pseudo-Newtonian plateau was reached from approx. 1 sec 1. Capillary viscosity values corresponded reasonably well with the second run steady shear data. The slope at high shear rates was close to -0.91 which corresponds nicely to the first-run steady shear run. All this could suggest, that this system is not completely melted, but still has some solid like regions incorporated. At 300°C capillary viscosity data showed an almost pseudo-Newtonian plateau. This corresponds quite well to the fact that fiber spinning as mentioned earlier was difficult and almost impossible below 290°C, but easy at 300°C. At an apparent shear rate of 100 sec 1, a die-swell was found to be approximately 0.95. 

The primary mon-amines are in part colourless liquids, e.g., aniline, o-toluidine, xylidine or colourless solids like p-toluidine, pseudo-cuminidine, the naphthyl amines, etc. They can be distilled without decomposition, are volatile with steam, and difficultly soluble in water. The di- and poly-amines are for the most part solids, non-volatile with steam, and much more readily soluble in water than the mon-amines. 

A successive X-ray study [64] showed that in the solid state calix[8]arene 1,5-diquinone 32a adopts a pseudo-chair-like conformation (Fig. 7.18). In this structure, two anti-oriented 3/4-c(Mie moieties can be seen (in magenta and green in Fig. 7.18) while the two quinone rings (in grey) are on parallel planes. Two quinone oxygens point towards the centre of the molecule with a short distance of 3.27 A [64]. 

The resulting star-like macromers with CTA were solid materials with distinct crystallinity, even at 20 and 40% HPL (Fig. 6). This suggests that even short CTA chains (i.e., DP 12) have the ability to organize into a crystalline lattice, thereby serving as pseudo-crosslinks. Depending on the chemical nature, and the molecular weight, multiphase materials result with variable mechanical properties. Above Tm of the chain segment,... 

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