THE EFFECTS OF INTERMOLECULAR FORCES ON POLYMER RHEOLOGY. III. IONIC FORCES ABOVE TG.

In an effort to determine the effects of ionic interactions on the physical properties of polymers, two series of butadiene copolymers were tested for stress strain and stress relaxation behavior. The first group of copolymers were those of butadiene and methacrylic acid which were converted to their anionic form by titration with LiOCH3. The second series were copolymers with 2-methyl, 5-vinyl pyridine which were reacted with CH3I to form the polycations. Finally stoichiometric mixed polysalts were prepared by mixing solutions of the oppositely charged polyions. The modulus-temperature currves of the various materials showed relatively stable plateau values over moderate temperature spans. Both the pyridinium copolymers and the mixed polysalts showed sharp decreases in modulus over a narrow temperature range. This unusual behavior was confirmed in the stress relaxation tests, being manifested as a rapid increase in the shift factors and E(visc), the activation energy for viscous flow. The patterns indicate a transition of one form or another but whether it is indicative of the onset of ionic interchange is not clear. (Author)
See also Part 2, dated Mar 66, AD-630 019.