Polyethylene oxide coils

PGSE measurements on polyethylene oxide) in aqueous dextran solutions were performed by Brown and Stilbs A2) as function of the concentrations of both polymers. The results for D(PEO) depend on the product of the concentration and the intrinsic viscosity of the dextran (host) component, and suggest that coil overlap in the concentrated host solution is the principal impediment to PEO diffusion. 

Lee et al. also reported on small rod—coil systems with a mesogenic rod segment. Their molecules are based on flexible polyethylene oxide) or polypropylene oxide) as a coil block.62-63 The rod—coil molecule based on poly(ethylene oxide) coil (8) exhibits a... 

Lee et al. also reported the assembling behavior of coil—rod—coil ABC triblock molecules where the rod block is connected as the middle block, consisting of polyethylene oxide) with different degrees of polymerization, two biphenyl unit as rod and docosyl coil (Chart 4).67 All of the coil—rod—coil ABC triblock molecules (12) exhibit three different crystalline melting transitions associated with polyethylene oxide), docosyl, and rod blocks, respectively, as determined by DSC, indicative of phase separation among blocks. 

Lee et al. showed that control of the supramolecular structure in rod—coil molecular systems containing either polyethylene oxide) (8) or polypropylene oxide) (17) coils and induction of ordered structures... 

When describing dilatant behavior, the maximum stretch rate, e, in the converging flow at the contraction is a better parameter, but more difficult to be calculated. Instead of the term stretch rate, other authors also used deformation rate (e.g., Chauveteau, 1981) or elongational rate (e.g.. Sorbic, 1991). The shear-thickening viscosity is also called elongational viscosity (often referred to as the Trouton viscosity Sorbie, 1991) or extensional viscosity in the literature. James and McLaren (1975) reported that for a solution of polyethylene oxide (a flexible coil, water-soluble polymer physically similar to HPAM), the onset of elastic behavior at maximum stretch rates was of the order of 100 s and shear rates of the order of 1000 s. In this instance, the stretch rate is about 10 times lower than the shear rate. However, some authors use shear rate instead of stretch rate in defining the Deborah number—for example, Delshad et al. (2008). 

Calculate the segment density distribution in a random coil of polyethylene oxide (PEO) at 0 conditions. Assume for the persistence length Inm (-three ethylene oxide units). Do the calculations for [-CH2-CH2-0-]5oo and [-CH2-CH2-O-15000-... 

It appears, then, that the mechanical degradation process is intimately connected with the molecular structure of the macromolecule and the resulting fluid rheology that arises from this structure. For a flexible coil macromolecule, such as HPAM or polyethylene oxide, the polymer solutions are known to display viscoelastic behaviour (see Chapter 3) and thus a liquid relaxation time, may be defined as the time for the fluid to respond to the changing flow field in the porous medium. It may be computed from several possible models (Rouse, 1953 Warner, 1972 Durst et al, 1982 Haas and Durst, 1982 Bird et al. 1987). The finite extendible non-linear elastic (FENE) (Warner, 1972 Bird et al, 1987a Haas and Durst, 1982 Durst et al, 1982) dumbbell model of the polymer molecule may be used to find the relaxation time, tg, as it is known that this model provides a good description of HPAM flow in porous media (Durst et al, 1982 Haas and Durst, 1982) the expression for fe is ... 

They studied solutions of polyethylene oxide (a flexible coil, water-soluble polymer similar physically to HPAM) flowing through porous beds of different grain sizes and reported the onset of elastic behaviour at maximum stretch rate to be of the order 100 s and shear rates of the order 1000 s" More recently, Durst and Haas have made an extensive study of the flow of viscoelastic polymers in porous media (Durst et al, 1981, 1982. Haas et al, 1981a, b). They characterised the onset of high resistances by using a product of a resistance factor / and the Reynolds number Re, defined as ... 

Chem. Descrip. Oxidized polyethylene aq. emulsion based on A-C 392 CAS 68441-17-8 EINECS/ELINCS 200-815-3 Uses Lubricant, antiblocking agent, mar resist, aid, rub resist, aid for paints, coatings, varnishes, can and coil coatings, textiles, leather, building materials, inks, graphic arts lubricant, mar resist, aid, rub resist, aid, water resist, aid in floor finishes... 

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