Elastomer Solution Research Articles

Determination of the diffusivity in elastomer solutions by batch sorption studies from a dilute liquid phase

A simple batch sorption method is examined for diffusivity determinations of binary solutions of low molecular weight organic compounds in amorphous polymers. The method is based on solute uptake from a stirred liquid solution by a polymer sheet sample submerged in the liquid solution and measurement of the liquid-phase concentration as a function of time. A transport model is discussed for the transient process of mass transfer between the stirred solution and the polymer phase, accounting for swelling of the polymer sheet and for concentration dependence of the diffusivity. The diffusion coefficient is evaluated by curve fitting of the results of numerical solution of the model equations to experimental data. Experimental toluene diffusivity data for the elastomers EPDM and PDMS are presented, as determined by the batch sorption method using an aqueous solution as the liquid phase. Good agreement between the experimental data and the calculated sorption curves is observed. A key parameter of a free-volume theory for diffusion in amorphous polymer was determined, by which the binary diffusion coefficient can be determined as a function of the composition and temperature, for a variety of diffusing solute compounds in the two elastomers examined. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 347–353, 1997

Express Method for Determination of the Antiozonants Efficiency

Abstract An express method for determination of the efficiency of antiozonants, based on their inhibiting effect towards ozone degradation of elastomers in solution, is proposed. An efficiency coefficient of the antiozonant was defined as a ratio between the amount of ozone consumed in an elastomer solution containing antiozonant and the amount of ozone that reacted in a solution without antiozonant, through which an equal decrease in the relative viscosity of both the solutions is attained. A stoichiometry coefficient of the protection effect can be determined by monitoring the changes in inhibiting activity of the antiozonants during their ozone conversion. The proposed method was demonstrated in the study of the inhibiting effect of the N-phenyl-N′-isopropyl-p-phenylenediamine, polimerised 1,2-dihydro-2,2,4-trimethylquinoline and tributhylthiourea antiozonants.

Vas deferens occlusion by percutaneous injection of polyurethane elastomer plugs: Clinical experience and reversibility

A non-incision method of vas occlusion based on the percutaneous injection of polyurethane elastomer solution to form plugs is described. The results are based on clinical experience in 12,000 men in which only 56 cases of minor complications were recorded. Follow-up of 500 men for up to 3 years demonstrated an azoospermia rate of 98%. Plugs have been removed from 86 men and, to date, 51 have made their wives pregnant. In those from which the plugs have been removed for more than 1 year (n = 31), the pregnancy rate is 100%.

Viscoelastic behavior of concentrated oil solutions of sulfonated polymers. V. Effect of metal stearate plasticizers

AbstractLinear viscoelastic studies of concentrated blend solutions of metal neutralized sulfonated elastomers and low molecular weight metal stearate plasticizers are presented. The data of the magnesium and zinc salts of sulfonated EPDM polymer solutions in 100 N oil solvent as a function of magnesium and zinc stearate polar plasticizers show that addition of the latter species into the ionomeric elastomer solutions enhances their low temperature relaxation spectrum. The changes in properties are directly related to the enhancement of ionic interactions and filler effects of the plasticizers. At high temperatures, the zinc stearate molecules behave more as a conventional plasticizer. For ionomeric associating polymers, the phenomenon appears to be quite general in nature. The enhancement in properties is found to be a function of the counterion structure on the ionomer and stearate. In the case of these solution blends, the studies confirm that an ion‐exchange process can occur, especially at high temperatures, resulting in the counterion on the stearate moieties “exchanging” ionic sites on the ionomer. Apparently, this process proceeds quite slowly at low temperatures. However, it is clear from these measurements that the incorporation of metal stearates into the ionomeric solution changes the network structure at both low and high temperatures.

Copolyether-urethanes as materials for artificial hearts.

A method has been developed for constructing artificial hearts from Biomer elastomer solution and from a segmented copolyether-urethane (PU 1025). Durability and function tests of Biomer hearts are quite promising.