Xylene-polypropylene system

Coughlin and Canevari (1%9) have published experimental data on two systems at a variety of operating conditions the extraction of xylene from polypropylene and the extraction of methanol from polypropylene. These studies were conducted in a single screw extruder at low pressures and w was assumed to be small in comparison with w. Coughlin and Canevari developed a model which they used in conjunction with their experimental data to obtain a value for the diffusion coefficient. The values that they computed were of the order of 10 mVsec, which obviously means that the model is incorrect. Coughlin and Canevari also computed values for the mass transfer coefficient and found it to be independent of screw speed. This observation is particularly noteworthy since they saw no evidence of bubble formation. 

Alexandridis et al. have studied a number of block copolymers of ethylene oxide (EO), propylene oxide (-OCH2CHCH3-, PO) and butylene oxide (-OCH2CH(CH2CH3)-, BO) in water and in ternary systems with p-xylene. The polypropylene oxide and butylene oxide blocks are the hydrophilic portions. Obviously, the short methyl and ethyl branches will need to be included in any packing constraints considerations. 

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