Polymers for gas separations: the next decade

Membranes for gas separation

Interpenetrating polymer networks (IPN’s) are a unique type of polyblend, synthesized by swelling a crosslinked polymer (I) with a second monomer (II), together with crosslinking and activating agents, and polymerizing monomer II in situ (Sperling, 1974–1975 ; Sperling and Friedman, 1969). The term IPN was adopted because, in the limiting case of high compatibility between crosslinked polymers I and II, both networks could be visualized as being interpenetrating and continuous throughout the entire macroscopic sample.* As with other types of polyblends, if components I and II consist of chemically distinct polymers, incompatibility and some degree of phase separation usually result (Sperling, 1974–1975; Sperling and Friedman, 1969; Sperling et al., 1970a,b,c; 1971). Even under these conditions, the two components remain intimately mixed, the phase domain dimensions being on the order of hundreds of angstroms. If one polymer is elastomeric and one polymer is plastic at the use temperature, the combination tends to behave synergistically, and either reinforced rubber or impact-resistant plastics result, depending upon which phase predominates (Curtius et al., 1972; Sperling and Mihalakis, 1973; Sperling et al., 1971; Huelck et al., 1972). Among the other kinds of polymer blends discussed in this monograph, the graft-type copolymers are the ones most closely related to the IPN’s.

Interpenetrating Polymer Networks

A very large amount of information is available in the open literature on the diffusion, or transport, of small molecules in polymers. A comprehensive discussion of this field would require an amount of space exceeding by far the confines of the present monograph. It is to be hoped that this herculean but extremely useful task will be undertaken by some enterprising investigator, or investigators, in the not-too-distant future. In the meantime, a review is presented here of some of the important and more recent work on the diffusion of small molecules in both rubbery and glassy polymers. The main purpose of the review is to outline the thrust of this work and thus provide a perception of possible new developments in the field.

Diffusion of small molecules in polymers

Edible films made from natural resources ; microcrystalline cellulose (MCC), methylcellulose (MC) and corn starch and polyols - Part 2

Interpenetrating polymer networks of polyacrylate (A) and poly (urethane-urea) (U) were prepared by mixing lattices of self-curing polyacrylate and urethane-urea prepolymer followed by subsequent curing of each network. The structures of the mixtures were analyzed by the dynamic viscoelasticity and the electron microscopy. It was found that a phase inversion occurred from the “U-phase particles in A-phase matrix” to the “A-phase in U-phase matrix” at A/U ≑ 30/70 as the U-phase content increases.



With increasing A-phase content, tensile strength started to increase and elongation-to-break becomes almost constant after the A-phase formed a continuous phase. This implies that the tensile properties are closely related to the morphological features.

T. K. Kwei

Papers

Structure‐Property relationships in polyacrylate‐poly(urethane‐urea) interpenetrating polymer networks

Modified Free-Volume Theory of Penetrant Diffusion in Polymers

Chemiluminescence of incompatible polymer mixtures