Dynamic mechanical relaxation effects in some poly(arylene sulfones)

Abstract

synopsisPoly-4,4'-oxydiphenylenesulfonyl and poly-4,4'-methylenediphenylenesulfonyl were synthesized by an electrophilic substitution polymerization of the arylene monosulfonyl chloride monomers. The glass-transition temperatures T, of these polymers were determined by calorimetric and dynamic mechanical measurements, and the number-average molecular weights were determined by vapor-pressure osmometry. Both polymers were found to have the same T, at equivalent molecular weight; the limiting value a t high molecular weight is 238°C. Both polymers have two dynamic mechanical relaxation peaks at temperatures far below T,. One is in the neighborhood of O"C, and the other is at -110°C. Plausible origins for these relaxations, and the absence of any near 0°C in poly(4,4'-isopropylidenediphenylen~,4'-~~1lfony~diphenylene dioxide), are discussed. 14. J. M. Barrales-Rienda and D. C. Pepper, J . Polym. Sci. B, 4,939 (1966). riam, J . Po/ym. Sci. A-1, 5 , 2378 (1967).

Radiation crosslinking of poly(butylene succinate) in the presence of low concentrations of trimethallyl isocyanurate and its properties

“…The γ relaxation of polymers such as polyethylene, poly(methyl methacrylate), and polystyrene can be attributed to the molecular motions of short branching or the local motion of chains existing on the crystallite surface, or both. For rigid aromatic polymers the low‐temperature mechanical relaxation can be attributed to the local motion of aromatic units in the main chain 17–19. The γ‐relaxation peak of the crosslinked sample broadened, which also could be a result of the local motion of cyclic units in the main chain, and the β‐relaxation shifts to a higher temperature could be from an increasing glass‐transition temperature ( T g ).…”

Mechanical properties of electron‐irradiated polysulfones

“…The low-temperature y peak of polymer I1 was attributed to the relaxation of the phenylsulfonyl groups by Baccaredda et a1.l and by Kurz e t al. 3 Robeson et aL4 indicated that the relaxation of the phenylether groups overlaps the relaxation of the sulfonyl moiety. For polymer 111, the y relaxation is attributable to the relaxation of the phenylether groups and/or the phenylester groups.…”

Influence of electron beam irradiation on properties of fluorine‐containing poly(aryl ether ketone)s

“…This relaxation temperature and the magnitude of tan δ are not remarkably changed on the dried film. Therefore, this relaxation is not influenced by water uptake as reported 9, 15–17. This kind of relaxation has not been reported on the spectra of PEEK and noncrystalline PEEK, but the relaxation at −80°C was observed as the relaxation arising from the aryl ether group, called mechanical secondary relaxation or low‐temperature mechanical relaxation 17, 35.…”

“…These results suggest that movement of polymer chains in the glassy state is restricted by the irradiation because of the structural change of F‐PEK to a more rigid structure. This kind of phenomenon was also characterized on the irradiated PEEK film and was never observed on PS and PES 15–17. The lowering of the glass transition of PS and PES was accounted for by lowering of the cohesive energy density attributed to polymer chain scission.…”

“…In the last few decades many aromatic polymers showing good resistance to degradation by high‐energy radiation have been developed to be used as materials in high‐energy radiation environments, such as those found in the nuclear and aerospace industries 4–7. Among them, poly(ether ether ketone)s (PEEK)4, 8–11 and polyamides6 exhibit better resistance than that of other aromatic polymers such as poly(sulfone)s (PS),12–14 poly(ether sulfone)s (PES),13–18 and polyesters 14, 19. However, their potential is less than that of polyimides represented by Kapton 20–24…”