Polyethylene systems

There Is a large body of experimental literature relating to polymer fractionation In liquid-liquid equilibria. In addition, numerous authors have analyzed polymer fractionation using Flory-Huggins theory. We have considered use of the corresponding states theory to model polymer fractionation for the ethylene/ polyethylene system at reactor conditions (18). Results of the... 

Recent preliminary studies (8,9) indicate that when specific inorganic salts such as lithTum perchlorate and nitrate are used to replace mineral acid, analogous grafting enhancement is observed in the styrene polyethylene system, representative results being shown in Table III. Since this salt work, the first... 

ISO/TR 11647 1996 Fusion compatibility of polyethylene (PE) pipes and fittings ISO 12176-1 1998 Plastics pipes and fittings - Equipment for fusion jointing polyethylene systems - Part 1 Butt fusion... 

In the irradiation of polyethylene Dole et al.71 have found that the initially present vinylidene unsaturation decreases markedly with dose and have suggested a free-radical migration mechanism. Charge transfer could equally well explain these results this would be a direct extension of the results from solid n-hexane to the polyethylene system. The close correspondence of these two systems in their response to high-energy radiation will be pointed out below. 

Wang, D. Y Liu, Y Ge, X. G Wang, Y. Z Stec, A., Biswas, B Hull, T. R and Price, D. 2008. Effect of metal chelates on the ignition and early flaming behaviour of intumescent fire-retarded polyethylene systems. Polymer Degradation and Stability 93 1024—30. 

The scope of this method is by far too broad to be presented in detail. The on-line NIR technique is especially valuable for studies under unusual or extreme conditions. The fluid phase equilibrium in the ethene-polyethylene system has been studied by Nees (1978) up to 300 °C and 3000 bar the solubility of adamantane, of octacosane, and of squalane in fluid CO2 up to 1000 bar has been determined NIR-spectroscopically by Swaid et al. (1985). 

Application of high-pressure vibrational spectroscopy in order to study and to monitor technically relevant fluid phase processes under extreme conditions is exemplified by high-pressure ethene polymerization. Several vibrational bands in the IR and the NIR may be used to detect concentrations directly in the ethene/polyethylene system (Buback, 1984). Some of these are plotted in Fig. 6.7-20. The conversion of unsaturated (ethylenic)... 

Ethylene-o-dichlorobenzene system, 39 Ethylene glycol, 181,182, 327 Ethylene-methanol system, 183 Ethylene-naphthalene system, 69 Ethylene-polyethylene system, 319 Ethylene-n-propanol system, 39 Ethylene-water-organic solvent phase diagrams, 71 Explosives, 347 Extractibility, 367... 

The most intensely studied species are the group 6 pentacarbonyls, M(CO)5(H2), which have been observed in rare-gas matrices, in liquid Xe solutions at - 70°C (a very useful medium), in alkane solvents, and in the gas phase. Perhaps the most novel preparation is photolysis of the hexacarbonyls impregnated in polyethylene disks under H2 or N2 pressures to give M(CO)6 n(L)n, where n = 1,2 for L = H2 and 1-4 for N2.175 Reactivity follows the order Mo > Cr > W, and H2can displace coordinated N2 in the polyethylene systems. In all media, vibrational spectroscopy provides evidence for H2 rather than dihydride binding, and the H-H, H-D, and... 

HAR Haruki, M., Takakura, Y., Sugiura, H., Kihara, S., and Takishima, S., Phase behavior for the supercritical ethylene + hexane + polyethylene systems, J. Supercrit Fluids, 44, 284, 2008. 

The polyethylene system, a loosely connected bond network, was chosen as a worst possible case in order to illustrate the limitations of classical MD simulation. Systems with external constraints (such as nearby chains in a crystal) or cyclical bond networks would be expected to exhibit significantly restricted motion. In fact, classical simulations of carbon nanotubes, which have a two-dimensional bond network, showed a sizeable but significantly smaller disagreement with quantum results. 

Nies, E., Stroeks, A., Simha, R., and Jain, R. K., LCST [lower critical solution temperature] phase behavior according to the Simha-Somcynsky theory apphcation to the n-hexane/polyethylene system. Colloid Polym. Sci., 268, 731-743 (1990). 

The ultra-high molecular weight polyethylene system exhibits the highest wear rate although it has the lowest friction coefficient [90]. 

The amount of wear in alumina-alumina couples can be as much as 10 times less than in a metal-polyethylene system depending on experiment conditions and surface roughness of the ceramic (Davidson, 1993 Kumar et al., 1S>91). The coefficient of friction of both alumina-alumina and alumina-polyethylene is less than that of metal-polyethylene because of alumina s low surface roughness and wettability (Boutin et al., 1988 Semlitsch et al., 1977). 

The most detailed investigation of single-molecule vibrational spectra has been carried out on the terrylene in polyethylene system by Tchenio et al. [38, 43, 44]. For this study the setup shown in Fig. 8 was used. Single molecule fluorescence spectra were obtained with excitation wavelengths both to the red and slightly to the blue of Aniax (569 nm) of the inhomogeneous distribution. 

We now examine the equilibration of a system containing 10 chains each of 78 units ( polyethylene ) at 450 K and 0.1 MPa. The mean-squared displacement of the chains vs cycles is linear as well (see Fig. 5) however, after almost 31000 cycles the mean-squared displacement is only 41.1 (not shown in Fig. S). Therdbre, the chains have displaced by only about one-third their unperturbed radius of gyration. Figure 6 shows Mi and M2 vs cycles and Fig. 7 shows the running average of for the two chains that have the largest and smallest initial values in the polyethylene system. We see that at the end of the... 

Fig. 7. Running average erf the squared end-to-end distance vs Monte Carlo c les for the chain that initially had the largest end-to-end distance and for the chain that initially had the smallest end-to-oid distance in a 10-chain 78-mer ( polyethylene ) system at 450K and Oil MPa. The horizontal line shows the value for continuous unperturbed chains...

Fig. 9a, b. Intra-chain pair density function radial distance a dotted curve result of bulk NPT Monte Carlo simulation of a 32-chain 24-mer (n-tetracosane) system at 450 K and 0.1 MPa dashed curve result from fast sampling of continuous unperturbed chains curves are neatly identical b dotted curve result from bulk NPT Monte Carlo simulation of a 10-chain 78-mer ( polyethylene ) system at 450 K and 0.1 MPa dashed curve result from fast sampling of continuous unperturbed chains... 

Full-water-reflected critical Infinite cylinder diameters are plotted as a function of Pu concentration in Fig. 2 for the same homogeneous systems. Very similar behavior is evidenced, with polyethylene systems being much more reactive than water-moderated systems, n-dodecane and ethylene glycol systems being slightly more reactive, and LA-2 stowing a crossover behavior. 

J. K. THOMPSON, Minimum Critical Mass of Plutonium-Polyethylene System Found to be Significantly Lower Than Plutonium-Water System, Nttcf. Techno/., 33, 235 (1977).-... 

Firstly Patterson et al. [10] calcidated "Yrt 12 3 nd Zfj for n-dodecane-branched polyethylene and -decaue-linear polyethylene systems to show how the interaction parameter may be calculated from chromatographic data. In the same year Hammers and de Ligny [57] determined X12 for -pentane-, benzene-, cyclochexane- and n-oetane-polyisobutylene systems from standard residual partial molar free energies of mixing at infinite dilution. Comparison of data extrapolated at 25 0 with those obtained from swelling and vapour pressure measurements at the same temperature [74—78] extrapolated to [Pg.143]

Acrylic toughening has been studied by Charnock and Martin in a methyl methacrylate/chlorosulfonated polyethylene system. The authors concluded that the classic toughening mechanism developed for rubber-toughened epoxies and polystyrene does not fully explain the acrylic-toughening observed. 

Fig. 13. Concentration dependence of the self-diffusion coefficient and the thermodynamic factor Q for the toluene-polystyrene system at 110°C and for the o-xylene-polyethylene system at 150°C. Q = (l a>A)(d In a /d In coa- From Ref. 45.

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