Gelation modes

Dalgliesh, D.G. Home, D.S. Different coagulation and gelation modes of casein micelles followed by diffusing wave spectroscopy. In Protein Interactions-, Visser. H., ed. VCH Verlagsgesellschaft, Weinheim, Germany 1992, pp 87-101. 

Helen, W., de Leonardis, P., Uhjn, R.V., et al. Mechanosensitive peptide gelation mode of agitation controls mechanical properties and nano-scale morphology. Soft Matter 7, 1732 (2011). doi 10.1039/c0sm00649a... 

The glass transition involves additional phenomena which strongly affect the rheology (1) Short-time and long-time relaxation modes were found to shift with different temperature shift factors [93]. (2) The thermally introduced glass transition leads to a non-equilibrium state of the polymer [10]. Because of these, the gelation framework might be too simple to describe the transition behavior. 

Most ultrafiltration membranes are porous, asymmetric, polymeric structures produced by phase inversion, i.e., the gelation or precipitation of a species from a soluble phase. See also Membrane Separations Technology. Membrane structure is a function of the materials used (polymer composition, molecular weight distribution, solvent system, etc) and the mode of preparation (solution viscosity, evaporation time, humidity, etc.). Commonly used polymers include cellulose acetates, polyamides, polysulfoncs, dyncls (vinyl chlondc-acrylonitrile copolymers) and puly(vinylidene fluoride). 

N-isopropylacrylamide 1 is added to the polymerization mixture to increase hydro-phobicity of the monolith required for the separations in reversed phase mode. Vinylsulfonic acid 12 provides the chargeable functionalities that afford electroosmo-tic flow. Since the gelation occurs rapidly already at the room temperature, the filling of the channel must proceed immediately after the complete polymerization mixture is prepared. The methacryloyl moieties attached to the wall copolymerize with the monomers in the liquid mixture. Therefore, the continuous bed fills the channel volume completely and does not shrink even after all solvents are removed. Fig. 6.8 also shows scanning electron micrograph of the dry monolithic structure that exhibits features typical of macroporous polymers [34],... 

Versteeg et al. (50) have isolated various multiple forms of pectin esterases in oranges and shown that they differ in affinity to pectins and pectates and in heat stability and therefore may play different roles in cloud loss phenomena. One form (about 5% of the total PE activity) was found to be much more heat stable than the other forms it was also active at low pH (2.5) and at low temperatures. Another form did not cause self-clarification for this enzyme a similar mode of attack was proposed as for fungal pectin esterases which produce low-ester pectins less sensitive to calcium. Multiple forms of pectin esterases are present in the fruits of all of the orange varieties and citrus species tested. The two isoenzymes known to be responsible for cloud loss and gelation in citrus products were found to occur in all of the component parts of the orange fruit (51). In the French cider industry the endogenous PE of apple is used for the self-clarification of apple juice (52). 

The role of the absolute configuration at C3 is determinant not only for aggregation/gelation but also for the aggregation modes of monolayers developed at the air-water interface [98],... 

In the nonionic system observed under EVM, the initial microemulsion showed no tendency of gelation until it reached 60 C. After reaching 60<>C, the system gels and starts to polymerize after 10-12 hours. As polymerization proceeds, the water separates out. After about 20-24 hours, the gel starts to become a solid with an excess emulsion phase formed at the bottom. The polymerization is essentially complete after 36 hours. Due to different modes of polymerization in the anionic and nonionic surfactant systems, the mechanical properties of the solid are different. The polymers obtsuned from anionic microemulsions are brittle, while those obtmned from nonionic microemulsions are ductile. 

We have investigated the free-radical polymerization of a variety of diallyl dicarboxylates extensively, especially DAP, DAI, and DAT, in terms of allyl polymerization, cyclopolymerization, and gelation [38]. The cyclopolymerization resulted in cyclization constants Kc of 7.5, 1.6, and 0.6 mol/L at 60 °C for DAP, DAI, and DAT, respectively. In this coimection, it should be noted that in the polymerizations of DAP, DAI, and DAT, two different modes of intramolecular cyclization should be considered. The cyclization reaction of DAP... 

In addition, the interesting finding that no difference in the actual gel point was substantially observed among three isomeric diallyl phthalates (see Table 4) has been discussed in terms of the correlation between gelation and the difference in cyclization modes, and the difference in reactivity between the uncyclized and... 

The Brookfield DV-II+-series rotational viscometers and DV-IIl-series rheometers have a built-in Time-to-Torque feature. The selected instrument is run in stand-alone mode, at one constant speed with one spindle. The motor rotation automatically stops at a user-selected torque reading that is a percent of full-scale range or "FSR." The elapsed time and the setpoint torque are then shown on the instrument s display. This system can therefore be used as a type of gel timer - the instrument monitors the torque increase to 90 % of full-scale range, for example, as the sample s viscosity increases during gelation. However, it is a "one-point" test - that is, only one data point is acquired. If the instrument s "continuous printing" mode is selected and a... 

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