Polyoxyethylenes, linear

Hazardous Ingredients Polyoxyethylene linear fatty alcohol phosphate, phosphoric... 

Furthermore, in a series of polyoxyethylene nonylphenol nonionic surfactants, the value of varied linearly with the HLB number of the surfactant. The value of K2 varied linearly with the log of the interfacial tension measured at the surfactant concentration that gives 90% soil removal. Carrying the correlations still further, it was found that from the detergency equation of a single surfactant with three different polar sods, was a function of the sod s dipole moment and a function of the sod s surface tension (81). 

The addition of linear chained alkyl alcohols shifts the percolation of AOT microemulsions to higher temperature, whereas the opposite effect is obtained by adding polyoxyethylene alkyl ethers [261]. 

In many polymerizations cyclic material is produced by a concurrent backbiting reaction as linear polymer is formed. For example dioxan Is formed In the cationic polymerization of ethylene oxide to polyoxyethylene, and polyoxyethylene can be degraded to... 

Each stationary phase is characterised by a calibration curve made with iso-molecular standards of known masses, M polystyrene in THF or polyoxyethylenes, pullulanes, polyethyleneglycols in water (Fig. 7.3 and Table 7.1). The curves representing log(M) as a function of the elution volume have a sigmoidal shape. However, by mixing stationary phases, the manufacturers can provide columns for which the calibration curves are almost linear for a wide range of masses. 

They are now being replaced by the polyoxyethylene derivative of straight-chain primary or secondary alcohols with C10-C18. These linear alcohol ethoxylate nonionic surfactants are more biodegradable than nonylphenol derivatives and have better detergent properties than linear alkylbenzenesulfonate. 

Calibration graphs of polyoxyethylene, octylphenyl and nonylphenyl ethers with a scale range of 0.05 absorbance units were linear between 0 and 20pg. 

The effects of surfactants on the hydrolysis of 2,4-dinitrophenyl sulfate are, however, smaller in magnitude (Fendler et al., 1970a). Above the critical micelle concentration both CTAB and polyoxyethylene(24) dinonylphenol, Igepal DM-730, increase the rate of the neutral hydrolysis of 2,4-dinitrophenyl sulfate by factors of 3-15 and 2-58, respectively, but NaLS has no effect (Fig. 8). A good linear relationship was obtained between — 10 /(i — o) a fid lj Gj — CMC) (equation 10a) from which the binding constant between 2,4-dinitrophenyl sulfate and CTAB was calculated to be 1-9 x lO M . This value was found to agree well with... 

The autooxidation of linoleic acid has been investigated as a function of polyoxyethylene(23) dodecanol (Brij 35) and linoleic acid concentration (Swarbrick and Rhodes, 1965). At constant surfactant concentration, the rate of oxidation increased linearly with increasing linoleic acid... 

Toshima, S., Moriya, T. Yoshimura, K. 1992. Effects of polyoxyethylene (20) sorbitan monooleate on the acute toxicity of linear alkylbenzenesulfonate (C12-LAS) to fish. Ecotoxicol. Environ. Safety 24 26-36... 

A wide variety of this group of surfactants is commercially available. They include some of the Tritons (alkyl phenol additives, as far as they are non-ionic). Tweens (sorbitan fatty acid ester polyoxyethylene ethers). Spans (sorbitan fatty acid esters) and alkyl polyoxyethylenes (C Ej, where n and x stand for the number of CH2- or CH3-. and CHjO-groups in the hydrophobic and hydrophilic parts of the molecule, respectively). Given our interest in the fundamentals we shall emphasize only the last-mentioned group, and only when n and x are sharply defined emd the two moieties are either linear or branched in a defined way. Unless specified otherwise, there is an OH-group at the end of the E-chain. Notwithstanding the non-ionic nature of these molecules, micelles sometimes appear to cany a (low) charge probably caused by preferential uptake of ionic species. 

Polyoxyethylene alkyl ethers are nonionic surfactants produced by the polyethoxylation of linear fatty alcohols. Products tend to be mixtures of polymers of slightly varying molecular weights and the numbers used to describe polymer lengths are average values. 

Polyoxyethylene alkyl ethers are prepared by the condensation of linear fatty alcohols with ethylene oxide. The reaction is controlled so that the required ether is formed with the polyethylene glycol of the desired molecular weight. 

A relationship between the lipophilicity of the solubilisate, expressed by the partition coefficient between octanol and water, Poctanoi (see Chapter 5), and its extent of solubilisation has been noted for the soluhilisation of substituted barbituric acids by polyoxyethylene stearates, of substituted benzoic acids by polysorbate 20, and of several steroids by polyoxyethylene nonionic surfactants. An exhaustive survey of data for the solubilisation of some 64 dmgs by bile salt micelles revealed linear relationships between log (partition coefficient between micelles and water) and log Poctanoi ach of seven bile salts... 

A similar detergency maximum at almost the same oxyethylene content has been observed in the removal of oily soil from metal surfaces using similar surfactants in an alkaline, built formulation (Komor, 1969). The maximum here is at 68% oxyethylene (about 11 oxyethylene units per nonylphenol) at bath temperatures from 40 to 80°C. For a series of polyoxyethylenated nonrandom linear alkylphenols with Cg-Cig alkyl chains, optimum removal of sebum soil from cotton at 49°C and 50 and 300 ppm water hardness was obtained at 63-68% oxyethylene content (Smithson, 1966). A study of the removal of oily soil from cotton and permanent press cloths, and of clay from permanent press cloths by commercial POE alcohols, showed that POE Ci2-Ci4 alcohols with 60% or greater ethylene oxide content achieved the best soil removal (Cox, 1989). 

Comparable results were obtained in formulations containing sodium silicate as a builder together with (M-5% sodium tripolyphosphate, using 250 ppm hard water and a bath temperature of 49°C (Illman, 1971). A nonionic surfactant prepared by polyoxyethylenation of a C12-15 alcohol mixture with 9-11 mol of ethylene oxide generally showed similar detergency to an anionic prepared by sulfation of a Ci2 i5 alcohol mixture previously polyoxyethylenated with 3 mol of ethylene oxide at all percentages of sodium tripolyphosphate, and both were considerably superior to a linear tridecylbenzenesulfonate and a sulfated C16-I8 alcohol mixture. The nonionic was somewhat better than the sulfated POE alcohol for removing nonpolar fatty soil from Dacron-cotton permapress, and the reverse was true for the removal of polar soil from Dacron-cotton permapress and carbon soil from cotton, but similar results for the two surfactants were obtained for clay removal from both Dacron-cotton permapress and cotton, and polar and nonpolar fatty soil from cotton. 

Application of Eq. 5.4 to experimental data [13] led to values for linear coefficients of around 0.5, which is lower than 0.67, the theoretical value. The difference between the theoretical and experimental values can be explained in terms of the contact angle, which is greater than zero in the aqueous surfactant solutions used in the experiments. The decrease in liquid tension tends towards lower linear coefficients. For most practical situations, the following coefficients can be assumed 0.5 for aqueous surfactant solutions, 0.35 for most organic liquids and 0.6 for water without surfactant [13]. These numbers demonstrate the need for surfactant addition in most analytical procedures implemented in segmented flow systems, and Brij-35 (1.0 ml L-1 polyoxyethylene lauryl ether2 solution) is by far the mostly commonly used surfactant [16]. 

To allow for an access of two anchor groups to two identical or different active sites from the non-primed S subsites, the crystal structure of Ac-Leu-Leu-Nle-H bound to pS and pS of the yeast 20S proteasome was used as a template [34]. The entry of substrates into the proteolytic chamber is restricted by the bottle-neck of the a ring, which recruits from outside only fully unfolded linear polypeptides for digestion. This fact significantly restricts the choice of spacers for bivalent inhibitor constructs. Such a spacer should mimic as much as possible the unstructured polypeptide chain of an unfolded protein, and reach a length of about 50 A. Peptides of appropriate size are known to be rapidly degraded by the yeast proteasome, and thus linear polyoxyethylene (PEG) chains were selected as mimic of random-coiled polypeptide chains [37, 64], since this polymer is known to be highly solvated and... 

We also note that certain polymer melts crystallize partially upon cooling. The transition occurs at a well-defined temperature rf. Crystallization takes place only if the polymer has a perfect linear structure for instance, it must not contain any asymmetric carbon. However, this tacticity condition is not sufficient, since polydimethylsiloxane, which is perfectly periodical, does not crystallize under normal conditions. On the contrary, polyethylene and isotactic polyethylene crystallize easily. In general, these polymers contain a large amorphous fraction. This is why they are called semi-crystalline. In certain conditions, it is possible to prepare polymer samples that are perfect crystals, in particular by polymerization in situ of a crystal made of monomers (polydiacetylene and polyoxyethylene). 

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