Colloidal instability

Figure 8 illustrates the relationship between the surface concentration of the dispersed phase S and the coagulant dosage Ct necessary to affect a certain degree of colloid instability at constant pH. If the described model of destabilization is correct, one should observe a direct relation-... 

A specific example of this behavior is shown in Figure 12.9 [23] where the viscosity of AlgOg suspensions is plotted as a function of pH. Near the isoelectric point, the viscosity is hi due to the colloid instability and the formation of floccs, and away from the lEP the viscosity is low due to colloid stability. 

From the above summary of experimental investigations into Uving miniemulsion polymerization, we can see that controlled mini emulsion polymerization (SFRP, ATRP, and RAFT) is less colloidal-stable during polymerization than its non-living counterpart. Colloidal instability leads to phase separation in the worst cases. In improved cases, the latex that results from the controlled mini-... 

The above argument suggests that the initial droplet size distribution may play an important role in super-swelling or colloidal instability. This indicates that one should monitor the emulsification procedure for controlled free radical emulsion polymerization closely. 

Data on Bonderite 37 treated steel are shown in Table IV. The samples are listed in order of reduci-bility. The difference in coating weights between reducible and non-reducible systems is clearly evident. The former deposit coating weights in the same range as for an amine-stabilized styrene/butyl acrylate latex. The latter was coated at pH 4 because of colloidal instability at a higher pH. 

Many attempts have been made to characterize the stability of the colloidal state of asphalt at ordinary temperature on the basis of chemical analysis in generic groups. For example, a colloidal instability index has been defined as the ratio of the sum of the amounts in asphaltenes and flocculants (saturated oils) to the sum of the amounts in peptizers (resins) and solvents (aromatic oils) (66) ... 

The major factors limiting the In vivo effectiveness of the proteln/DNA complexes may be the poor bloavallablllty to many target cells and their colloidal Instability In physiological media. The endocytotic uptake of the receptor complex also limits the effectiveness of the delivery system, because the DNA Is quickly destroyed In the endosome/lysosome pathway. 

The basic CRP techniques and mechanisms are discussed in Chapter 4 here only those issues associated with the presence of water in the system are dealt with. The subject has been reviewed by several authors [206, 266, 267]. Perhaps the most important challenge in this field is the development of a robust and general ab initio emulsion process (without using a seed). An essential problem in this endeavor is to avoid the nucleation in monomer droplets, which causes colloidal instability. 

Despite their unusual and interesting optical and electronic properties, inorganic QCNs have inherent disadvantages like toxicity (heavy metal based, e.g., CdTe QDs [112]), costly precursors, high density, and sometimes colloidal instability or compatibility issues. This prompted the researchers to look for better alternatives and the perfect answer has been found in terms of organic QCNs viz. C-dots, GNRBs, and GQDs [50,113-116]. They... 

Stripping No toxic solvents required Tendency to foam Possible thermal degradation of polymer Colloidal instability of the latex High throughputs of the stripping medium required... 

When colloid instability artifacts are evident, use TEM to detect their nature and assess their extent, then use TEM as a monitor to aid method modifications designed to minimize the artifacts (tuning the method to suit the sample). 

In fact, none of the LRP techniques are easily performed via emulsion polymerization and it is common to observe colloidal instability and loss of polymerization control in all cases. The general cause of these problems involves mass transfer limitations of the controlling species which are usually not soluble in water and recent reviews describe in detail the mechanisms that cause these problems [32-35]. However, some recent progress has been made in developing emulsion systems for NMP reactions, typically by using water-soluble nitroxides [36, 37]. 

Colloidal instability (coagulation) (291) in latexes can become an issue when the latex is sheared through pumping or mixing (shear-induced coagulation) when the latex is frozen and then thawed (freeze-thaw stability) when contaminants or additives are... 

Colloidal instability due to interactions between polyphenols and proteins limits the shelf life of beer. A lag phase is usually observed in lager beers before chUl-haze development [23-25]. The time needed to form critical amounts of tanning polyphenols leading to visible chiU-haze particles corresponds to the lag phase. As described by Leemans et al. [25] for different batches, the longer the lag phase, the better the colloidal stability. 

Catechin does not rapidly induce strong haze. Upon storage, however, it does. Likewise, colloidal instability caused by dimers and trimers is enhanced after oxidation (not true for tetramers and pentamers) [26-28]. Free radicals are known to enhance haze [29]. Tannoids have been defined by Chapon [30] as intermediates in the oxidatimi of simple flavanoids to tannins, forming complexes with proteins. On the other hand, according to O Rourke et al. [28], oxidized flavanols cause chUl haze, but only subsequent polymerization leads to tannoids and permanent haze [28, 31]. 

Leemans et al. [25] have proposed a model in which aldehydes and oxygen play key roles in tanning polyphenol formation [25, 31]. Not CMily dissolved oxygen but also shaking, higher temperature, polyphenol-rich raw materials, light, and heavy metals will significantly increase colloidal instability [25, 31]. 

Colloidal instability, 2335 Colloidal stability, 2342 Colon, 4118, 4120,4127,4133,4136 Colon adenocarcinmna, 1836 Colon cancer (CCa), 2403, 3485 incidence, 2409 mOTtality, 2409 Colon cancer cell, 3485 Colon tissues, 2295 Color, 1755, 1807, 2343,2350 Color-developing agents, 3314 Colorectal cancer, 2302 Colpomenia... 

Since hydrolysis of SSC during polymerization might be responsible for colloidal instability and polydisperse latexes, its stability in water was tested as follows at 25 °C and at 60 °C (the temperature used for emulsion polymerization). D2O was added to a solution of acetone/SSC to give a two-phase mixture, and the... 

There are no standard tests for measuring the onset of asphaltenes precipitation. Among the techniques and analytical methods frequently used to measure sediment and asphaltenes onset for the adjustment of different process parameters in the refineries are spot test (ASTM-D-4740-95) total sediment (ASTM-4870-96) solubility parameters, optical microscope light scattering (PORLA) peptization value (P-value) ° colloidal instability index (CII) coking index. ... 

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