Investigation by electron microscopy and x‐ray diffraction of the microstructure of permselective membranes made from polyethylene

Abstract

Abstract Ion‐permselective membranes containing polyethylene in their base material have been examined by direct transmission electron micrography and x‐ray diffraction. All of the electron micrographs showed white lines of about 100 A. thickness between somewhat thinner black lines composed of granules. These lines often occur as black‐white‐black triplets. We tentatively explain these structural elements by assuming that they are cross sections of the crystallite platelets, characteristic for polyethylene, reacted on both of their faces during sulfochlorination. It is known, that these platelets are about 100 A. thick, X‐ray diffraction experiments also showed the characteristic lines of polyethylene crystallites, their intensity decreasing after sulfonation. The velocity of heterogeneous sulfochlorination of polyethylene sheets decreases abruptly when the film contains 6% S and 7% Cl (after hydrolysis). This m̀eans six substituted sites on a chain element across the platelet for a 100% crystalline film and accordingly less for a partially amorphous material. It is known that five CH 2 groups of each chain element are exposed at the surface of the platelets, in good agreement with our findings.