Sorption of moisture on segmented poly(urethane3ureas) with flexible segments of various chemical structures and the effect of a humid atmosphere on the mechanical properties of these materials were studied. Poly(urethane3urea) prepared from mixtures of oligoethers shows advantages from the viewpoint of preservation of high strength in a humid atmosphere.Block polyurethane elastomers, so-called segmented polyurethanes (SPUs), are widely used in various branches of industry thanks to their high strength, good deformation characteristics, and resistance to a number of solvents [1]. Depending on the destination, polyurethane items can operate in air or in direct contact with water (e.g., polyurethane coatings of squeeze rolls in paper-making industry).Published data on the behavior of SPUs in moist media mainly concern the moisture transfer in these materials [235] and changes in the structure [2, 5, 6] and glass transition point [5, 6] of moistened polyurethanes. Experiments were performed with thin polyurethane films prepared from solution; in this case, correct estimation of changes in mechanical properties on moistening is complicated by intense moisture exchange with the surrounding medium. Data on the mechanical properties of the films are limited to the results of their mechanical tests before moistening [3]. Therefore, it is unclear to what extent the mechanical characteristics of various SPUs vary on moistening and how the extent of their variation depends on the polymer structure.Studies in this direction are necessary for understanding how the mechanical characteristics of polyurethanes change on moistening and for choosing formulations of polyurethane materials suitable for operation in moist media.In this study we examined the influence of the relative air humidity, varied in a wide range, on the mechanical properties of SPUs with various flexible segments. Our main goal was to reveal what structure of flexible blocks would provide the highest strength of the polyurethane material in a humid atmosphere. EXPERIMENTALWe used segmented poly(urethane3ureas) with poly(tetramethylene oxide) flexible blocks (SPUM-1), poly(propylene oxide) segments (SPUM-2), mixed polyether blocks (SPUM-3), and mixed polybutadiene3poly(tetramethylene oxide) flexible segments (SPUM-4). To prepare SPUMs, we took prepolymers based on oligo(tetramethylene oxide)diol (M~1700), oligo(propylene oxide)diol Laprol 2102 (M~1950), and polybutadienediol (M~2100, SKU-DF-2 prepolymer). The molecular weight of the oligomeric diols was estimated from the content of hydroxy groups. The prepolymers were prepared by the reactions of appropriate diols with toluylene-2,4-diisocyanate. The prepolymers and their mixtures (in preparation of SPUMs with mixed flexible segments) were cured with 3,3`-dichloro-4,4`-diaminodiphenylmethane (Diamet Kh) by the procedure described in [7].The molar ratio of the prepolymers (or their mixture) to Diamet Kh was 1.03, and the molar ratio of the NCO and OH groups in the synthesis of the prepolymers, 2.1.The isotherm...

The effect of a mixture of di(2-ethylhexyl) phthalate and tributyl phosphate on the properties of segmented polyether3urethane3ureas was examined. The data obtained for the elastomers with individual and mixed plasticizers were compared. The efficiency of using the binary plasticizer for controlling the properties of polyether3urethane3ureas was assessed.

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