Gel-like behavior

Fernandez et al. (2007) have characterized the rheological behavior of the mashed potatoes with added biopolymers using steady shear measurements. Fresh and frozen/thawed mashed potatoes present shear thinning with yield stress (Canet et al., 2005a), and dynamic shear data reveal weak gel-like behavior in potato purees (Alvarez et al., 2004). The effects are strongly... 

It was observed early on that solutions of PPEs in toluene are colorless at temperatures above 35 °C, while they turn yellow at room temperature. Almost all PPE samples prepared for 13C NMR spectroscopy show gel-like behavior at concentrations exceeding 5 % weight. Perahia et al. [61] investigated the behavior of the yellow/colorless toluene solutions of PPEs. 

Figure 4-30 shows the dynamic properties, storage modulus (G, Pa) and loss modulus G", Pa) versus frequency o> (rad s ) of gelatinized cross-linked waxy maize (CLW) starch dispersions of 3, 4, and 5% solids. In all dispersions, G was much higher than G", that is, the dispersions exhibited gel-like behavior over the studied range of frequencies. Both G and G" increased with concentration and showed a weak dependence on frequency at low values. This dependency was more pronounced in dispersions of higher concentration. 

The com starch-SP isolate dispersions displayed tme gel-like behavior. Table 4-12 contains magnitudes of the slopes ( and n") and intercepts (K and K") in the equations ... 

Applications . NMR has found the following applications in filled systems carbon black adsorption of SBR, the effect of carbon black loading on cure rate of natural rubber, gel-like behavior of polybutadiene/carbon black mixtures, structure and dynamics of carbon black filled rubber vulcanizalcs, " interaction of... 

E. Ruckenstein, Emulsion pathways to composite polymeric membranes for separation processes, Colloid Polym. Sci., 1989, 267, 792-797 J.P. Cohen-Addad and C. Bogonuk and V Granier, Gel-like behavior of pH dependent latex films, Macromolecules, 1994, 27, 5032-5036 T.-H. Young, L.-W. Chen and L.-P. Cheng, Membranes with a microparticulate morphology, Polymer, 1996, 37, 1305-1310. 

Harada and coworkers reported forming a photoresponsive hydrogel system by combination of a-cyclodextrin, dodecyl-modified poly(acrylic acid), and a photoresponsive competitive guest, 4,4 -azodibenzoic acid. An aqueous solution of dodecyl-modified poly(acrylic acid) exhibits a gel-like behavior, because polymer chains form a network structure via hydrophobic associations of Ci2 side chains. When a-cyclodextrin is added to the gel-like aqueous solution, the gel is converted to a sol mixture because hydrophobic interactions of Ci2 side chains are dissociated by the formation of inclusion complexes of a-cyclodextrin with the C12 side chains. Upon addition of 4,4 -azodibenzoic acid to the binary sol mixture of the modified poly(acrylic acid) and a-cyclodextrin, the cyclodextrin interacts predominantly with 4,4 -azodibenzoic acid ... 

In the whole range of measurement G -values are higher than G"-values independent of acrylate or PEG-12 concentration (Eigs. 2 and 3). The gel-like behavior shown here is also reported for multiple emulsion systems [33] and w/o-emulsions [34],... 

Fechner et al. indicated that for an optimum extrusion process, a mixture of spongelike and gel-like behavior might be desirable which are possible by the use of MCC and powder cellulose (39). 

Exponential t)q)e gels are possibly observed when the networks assume a hierarchical structure, which does not possess characteristic length. Clarke and Ross-Murphy [193] termed this gel-like behavior. 

Most of the multilayers show gel-like behavior [222]. However, Nolte et al. [222] pointed out that in the dry state the multilayers have a quite rigid behavior. The changes of geometry, from flat multilayers to capsules, do not modify the mechanical response of the polyelectrolyte layers. 

With certain products which exhibit gel-like behavior, exercise care that flow time measurements are made at sufficiently high temperatures for such materials to flow freely, so that similar kinematic viscosity results are obtained in viscometers of different capillary diameters. 

Even when no gel-like behavior occurs, that is, the precursor density is too low, the growing crystalline structures will form a mixture of a polymer melt and elastic solid-like particles that can be looked upon as a viscoelastic dispersion (anisotropic, in the case of fibrillar nucleation) [20,21,70]. 

Azodibenzoic acid (ADA) can be isomerized from trans to cis conformer under irradiation with UV light ca. 355 nm) and from cis to trans conformer under irradiation with visible light ca. 430 nm). These photoisomerism behaviors can be used in the design of photoinduced molecular shuttle [33], because a-CD can only interact with trans-kDA. but not interact with cw-ADA. Harada and his coworkers [34] have reported a kind of sol-to-gel and gel-to-sol transitions that can occur repeatedly by repetitive irradiations of UV and visible light. An aqueous solution of dodecyl (Ci2)-modified poly(acrylic acid) exhibited a gel-like behavior due to the polymer chains forming a network... 

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