Solubility of polyethylene

Fig. 4. Upper temperature limit for solubility of polyethylene oxide) in water. Molecular weight is 2 x 106 (3).

However, it should be borne in mind that, due to poor solubility of polyethylene oxide powder in water, certain difficulties are encountered in preparing solutions on its base. 

Xiong, Y, and Kiran, E., 1995. Comparison of Sanchez-Lacombe and SAFT model in predicting solubility of polyethylene in high-pressure fluids. J. Appl. Polym. Set, 55 1805-1818. 

In the preceding discussion of the operation of the tubular reactor polymerization scheme, we stated that the heat of reaction is removed by through-wall heat transfer. What exactly occurs in the vicinity of the wall If the characteristic of the high-pressure (300 bar) naphthalene isobar is interpreted as a schematic representation of the solubility of polyethylene in ethylene at a pressure of 2,700 bar, we can use it to predict that polyethylene will precipitate in the boundary layer near any relatively cold surfaces in the reactor or downstream lines. If the precipitation of polyethylene does occur on these internal surfaces and if it is not appropriately removed, the buildup of the polymer on the wall can result in decreased heat transfer from the hot gas-polymer solution, and the attendant decrease in heat transfer can lead to the runaway reaction that is occasionally encountered in high-pressure polyethylene plants. 

Figure 1 Catalyst recovery and product separation by temperature-dependent solubility of polyethylene oligomers. (Reprinted with permission of ACS from [la], 2002).

KIR Kiran, E. and Zhnang, W., Solubility of polyethylene in n-pentane at high pressures, Polymer, 33, 5259, 1992. 

Kiran, E., Zhuang., W. (1992) Solubility of Polyethylene in n-pentane at High Pressures, Polymer 33,5459-5263. 

The behaviour at normal temperatures against aromatic hydrocarbons (toluene, xylene) corresponds to the case just discussed. At high temperatures ( 80 °C), however, the effect of swelling is irreversible organic solvents can dissolve even a HDPE material under these conditions. This very poor solubility of polyethylene requires special high-temperature equipment in liquid chromatography for the determination of the molecule mass distribution or in viscosity measurement, since these measurements must be performed with a hot test solution. 

AGA A rwal, R., Prasad, D., Maity, S., Gayen, K., and Ganguly, S., Experimental measurements and model based inferencing of solubility of polyethylene in xylene, J. Chem. Eng. Japan, 37, 1427, 2004. 

Figure 1 Impact of solvent size, which is related to solvent quality, on the solubility of polyethylene in normal aUcenes (closed circles, ethylene open circles, propylene closed squares, 1-butene open squares, 2-butene) (8,9).

Table 1. Solubility of polyethylene-6-polyaimde [39], The molar masses of the oligoethers (PE) and ohgoamides (PA) are 3900 and 3200 (copolymer Ci) and 7400 and 8300 (copolymer G2), respectively. Processes I and II are described in the text. Solubility ++ soluble at room temperature, + soluble on heating, swelling, - insoluble...

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