Structure of ionic aggregates of ionomers. II. Effect of humidity and temperature on ethylene and styrene ionomers

Small-angle X-ray scattering profiles of ethylene and styrene ionomers were studied to clarify the structure of ionic aggregates as a function of humidity or temperature. The intensity and position of ionic cluster peaks were observed for ionomers with a certain degree of neutralization. The intensity of the ionic cluster peak for the ethylene ionomer increased with increasing relative humidity, but it decreased for the styrene ionomer. With increasing humidity, the position of the ionic cluster peak shifted to smaller angles for both ionomers. The size of the ionic aggregates and the closest approach distance between the aggregates were analyzed, and the results varied with humidity for both ionomers. The size did not vary markedly with a change in temperature, whereas the closest approach distance and number of ionic aggregates changed slightly with the melting temperature of the ethylene ionomer and the glass-transition temperature of the styrene ionomer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 831–839, 2002