Thermal, Dynamic Mechanical, and Dielectric Properties of Hydrogenated, Sulfonated Polypentenamers

Abstract

Hydrogenated, sulfonated polypentenamers containing from 2.9 to 19.l mol % pendant groups in the form of sodium salts were examined by differential scanning calorimetry (DSC) and dynamic mechanical and dielectric relaxation techniques. DSC results display two endotherms and provide evidence of a room-temperature annealing phenomenon. Four relaxations, a, {3, y, and y, in order of decreasing temperature, are observed dynamic mechanically. The a relaxation is composite in origin but appears to arise partially from an ionic-phase mechanism which suggests the existence of ionic clusters. The {3 relaxation is related to the glass transition and is affected by the crystalline content.• Large increases in l and tan 8. accompany the dielectric results. A dielectric a relaxation displays behavior that parallels that of the mechanical a peak. w e have reported previously the sulfonation of a polypentenamer (PP) under reaction conditions that preclude the formation of covalent cross-links (1). The sulfonated materials are isolated in the form of sodium salts to give ion-containing elastomers. The thermal and dynamic mechanical properties of the sulfonated PP's indicate the existence of phase-separated ionic clusters above a sulfonate concentration of roughly 10 mol % (2). It has been shown (1) that the unsaturation in the sulfonated PP' s can be removed by a diimide hydrogenation reaction to yield a material that is essentially linear polyethylene with pendant sulfonate groups. In this manner the effect of backbone crystallinity on

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A Review of the Glass Transition in Surlyns and Polypentenamer Ionomers

“…The unsaturated polypentenamer backbone can be hydrogenated (19) and this changes its character and that of its derivatives from essentially elastomeric to thermoplastic. Because of its linear nature and the fairly low substituent concentration range studied, hydrogenation leads to a high degree of crystallinity.…”