Oxyethylene Determination

Oxyethylene Content (apparent) Determine as directed under Oxyethylene Determination, Appendix VII, using 70 mg of sample, accurately weighed. 

Although the liquid crystalline phase of most polybibenzoates usually undergoes a rapid transformation into a three-dimensional crystal, the introduction of oxygen atoms in the spacer of polybibenzoates has been used to prevent or to slow down this transformation. The dynamic mechanical behavior of polybibenzoates with 2, 3, or 4 oxyethylene groups in the spacer (PDEB, PTEB, and PTTB, respectively) is determined by the composition of the spacer [24], as discussed in this section. 

ISO 2270 1989, Non-ionic surface active agents. Polyethoxylated derivatives Iodometric determination of oxyethylene groups. 

Dynamics of Poly(oxyethylene) Melts Comparison of 13C Nuclear Magnetic Resonance Spin-Lattice Relaxation and Dielectric Relaxation as Determined from Simulations and Experiments. 

Baleux B. Colorimetric determination of nonionic, poly(oxyethylene) surface-active agents using an iodine-iodide solution. CR Acad Sci Sci Chim 1972 274 1617. 

Kawaguchi et al.125) prepared an ionene-oxyethylene-ionene (IEI) triblock copolymer with the molecular weight 72 X 103 and measured its surface tension in aqueous KBr. They also determined by ellipsometry the adsorbance and the thickness of the adsorbed polyelectrolyte layer at the air-KBr solution interface as a function of the KBr concentration. The data obtained indicate that this copolymer is surface-active and that the effect of added KBr on the surface tension is stronger than in the case of polyoxyethylene (POE). 

CMC determinations as a function of temperature utilizing the change of the amount of solubilized water are inaccurate. This procedure has been frequently applied. In this way, for example, the effect of the temperature on the CMC of hexa-oxyethylene dodecylether in cyclohexane183) was determined. The CMC loses its well defined meaning in a ternary system, viz. to represent a thermodynamic property of the particular surfactant/solvent system (see Paragraph 2.2). 

From the field desorption mass spectra of standard samples, a table for identification of poly(oxyethylene) alkylphenyl ethers and determination of the degree of polymerisation of ethylene oxide was constructed as shown in Table 6.1 n is the number of alkyl carbon atoms and m is the degree of polymerisation of ethylene oxide. When the field desorption mass spectrum having a peak pattern with the difference of 44m/z was obtained such as the peaks at 484, 528, 572, 616 and 660m/z, Table 6.1 would show that those peaks are due to poly(oxyethylene) nonylphenyl ethers with the degree of polymerisation of 6-10 of ethylene oxide. Table 6.2 also shows the identification of poly(oxyethylene) dialkylphenyl ethers and determination of the degree of polymerisation of ethylene oxide based on calculations of the molecular weight. 

Apparatus The apparatus for oxyethylene group determination is shown in Fig. 35. It consists of a boiling flask, A, fitted with a capillary side tube to provide an inlet for carbon dioxide and connected by a condenser with trap B, which contains an aqueous suspension of red phosphorus. The first absorption tube, C, contains a silver nitrate solution to absorb ethyl iodide. Absorption tube D is fitted with a 1.75-mm spiral rod (23 turns, 8.5-mm rise per turn), which is required to provide a longer contact of the evolved ethylene with the bromine solution. A standard-taper adapter and stopcock are connected to tube D to permit the transfer of the bromine solution into a titration flask without loss. A final trap, E, containing a potassium iodide solution, collects any bromine swept out by the flow of carbon dioxide. 

FIGURE 10.20 (a) Normalized segment density distribution ivmction determined by neutron scattering for polyCvinyl alcohol) with a hydrodynamic radius of 18 nm, (b) poly(oxyethylene) cvirve 1 theoretical segment density distributions of the adsorbed polymer, taken from Hesselink [35], and curve 2 experimental results. Both experimental results taken from Cosgrove et td. [36]. Figure redrawn from Napper [27] with permission from Academic Press. 

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