We compare the ion exchange selectivity of phenol-type sorbents based on phenol formaldehyde resins, products of condensation of diatomic phenols with formaldehyde, and crosslinked polymer based on C-phenyl[4]resorcinarene resin, for cesium and rubidium ions. It is shown that phenol formaldehyde sorbents are the ones most selective. The interaction of alkali metal cations with the anion of calix[4]arene is investigated via quantum-chemical modeling. It is shown that the selectivity toward cesium and rubidium ions in ion exchangers of the phenolic type is not due to specific interactions of ions with phenolic groups.

It is shown that at a temperature of 295 K, phenol groups of phenol formaldehyde sorbents are characterized by the value pK ∼ 13.0–13.7. It is found that raising the temperature to 343 K reduces the pK value by one. It is concluded that the reason for the lower acidity of phenol formaldehyde sorbents relative to phenol in an aqueous solution is the smaller amount of firmly bound water.

The structure of aqua complexes of alkali metal ions Me+(H2O) n , n = 1−6, where Me is Li, Na, K, Rb, and Cs, and complexes of 2,6-dimethylphenolate anion (CH3)2PhO− selected as a model of the elementary unit of phenol-formaldehyde ion exchanger with hydrated alkali metal cations Me+(H2O) n , n = 0−5, was studied by the density functional method. The energies of successive hydration of the cations and the energies of binding of alkali metal hydrated cations with (CH3)2PhO− depending on the number of water molecules n were calculated. It was shown that the dimethylphenolate ion did not have specific selectivity with respect to cesium and rubidium ions. The energies of hydration and the energies of binding of alkali metal cations with (CH3)2PhO− decreased in the series Li+ > Na+ > K+ > Rb+ > Cs+ as n increased. The conclusion was drawn that the reason for selectivity of phenol-formaldehyde and other phenol compounds with respect to cesium and rubidium ions was the predomination of the ion dehydration stage in the transfer from an aqueous solution to the phenol phase compared with the stage of binding with ion exchange groups.

It is shown that ion-exchange sorbents based on phenol-formaldehyde resins can be used for a long time for isolating and separating rare alkali metals without any significant changes in the ion-exchange selectivity and capacity. When the phenol sorbents were used in alkaline solutions at elevated temperatures, carboxyl groups gradually accumulated in them as a result of the oxidation of methylol groups with oxygen dissolved in the solution. This led to a considerable increase in the ion-exchange capacity of the sorbents and a simultaneous decrease in the selectivity with respect to Cs + -Rb + and Rb + -K + ions (it is desirable to avoid the drying of phenol ionites in air by storing them in a swelled state in closed vessels).

The new phenomenon of a two-temperature non-reagent concentration of alkali solutions on sorbents based on the phenol-formaldehyde resin Amberlit XAD 761, PFR-1.4/0.7, and sulfonated phenol-formaldehyde ionite KU-1 was investigated. It was found that during an alkali solution’s passage through a column with a sorbent and a periodical change in temperature in the “cold” stage, the concentration of alkali in the filtrate appeared to decrease, while in the “hot” stage, the alkali concentration appeared to increase. It was shown that the increase in alkali concentration in a solution in contact with phenol-formaldehyde resin is determined by the ion-exchange properties of the phenol groups, and is associated with an increase in water dissociation upon a rise in temperature.

The influence of temperature on cation exchange on phenol groups of macroporous materials based on phenolformaldehyde resins (PFRs) was studied for Amberlit XAD 761 with irregularly shaped grains obtained by breaking up polycondensation resin blocks and FFS-1.4/0.7 with spherical granules. An increase in temperature caused some decrease in the sorption capacity of PFRs in the alkaline region, but almost did not influence the selectivity of alkali metal ion exchange. The sorption capacity and selectivity of PFRs did not change after multiple (dozens of cycles) transfer of phenol groups from the hydrogen to salt form and back. Ion exchangers of this type can effectively be used for separating mixtures of alkali metal ions containing cesium and rubidium.

Stress relaxation which occurs on applying a periodic deformation at constant amplitude and infrasonic frequencies to a uniaxially compressed rubber sample is studied experimentally. The application of vibrations during stress relaxation leads to an additional reduction in the relaxing stress. This process is called vibrorelaxation. The extent of the additional reduction in stress during vibrorelaxation increases substantially on raising the content of activating filler in the rubber.

Methods of determining the continuous and discrete relaxation spectra are analyzed with the object of choosing a characteristic describing the actual relaxation processes. It is shown that the discrete spectrum is a physically sounder characteristic and makes it possible to distinguish the most probable elementary relaxation processes. Problems of predicting the relaxation processes in real polymers can be simplified by using the discrete relaxation spectrum.