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W.M. Trochimczuk



The transport of organic vapors through interpolymers. Part. I. Tire isotactic polypropylene (PP-i)//polystyrene
and PP-i//poly(methyl methacrylate) systems


Polimery 1999, No 10, 666


DOI: dx.doi.org/10.14314/polimery.1999.666


Summary

Intermesh polymerization was used to prepare thin interpolymer membranes (IPM) involving networks 1 and 2 formed by iso tactic polypropylene (PPw-i) and polystyrene (PS) or poly(methyl methacrylate) (PMMA), respectively. Network 1 was swelled in styrene or methyl methacrylate, which contained benzoyl peroxide as initiator, at a temperature lower than the PPw-i dissolution temperature (Table 2) and, as step two, the swollen network was heated in, to interpolymerize with, an appropriate monomer. Membranes were prepared with up to 21.9 wt. % PS and 23.9 wt. % PMMA as the respective networks 1 and 2 (Table 3). Physical and mechanical properties of interpolymers and of the membranes containing PPw-i were determined (Tables 4, 5). Structural analysis carried out by electron microscopy showed the interpolymers to exhibit microheterogeneous structures with spherical microdomains of PS and PMMA (Figs. 2b, 2c). At network contents sufficiently high with respect to the PPw-i amorphous phase, the network phase was found to be continuous. Permeation of гг-hexane, benzene, chloroform, ethyl acetate and acetone vapors through the PPw-i membranes and interpolymers was followed gravimetrically at 25 °C. Diffusion rate (S), permeability (К ), diffusivity (D), and time lag were determined (Tables 6, 7). Incorporation of PS into the amorphous PPw-i phase was found to improve the transport of nonpolar vapors, whereas the introduction of PMMA improved the transport of polar vapors. Ethyl acetate and acetone vapors were found to permeate through each IPM examined, but not through any PPw-i membrane studied. These differentiated membrane transporting properties of IPM can be used to remove, separate or purify certain organic compounds


Keywords: isotactic polypropylene, polystyrene, poly(methyl methacrylate), interpolymerization, transport of vapors, modification of membrane transporting properties

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