METHOD FOR DETERMINING DIFFUSION COEFFICIENT OF SOLVENTS IN SHEET CAPILLARY-POROUS MATERIALS

摘要

FIELD: measuring equipment.;SUBSTANCE: method for determining the diffusion coefficient of solvents in sheet products made of capillary-porous materials is proposed, which consists in creating a uniform initial content of the solvent distributed in the solid phase in the test sheet material. Then the test material is placed on a flat substrate of a solvent-proof material, the upper surface of the material is hydroisolated, and at the reference time the impulse point wetting of the upper surface of the test product is carried out with a dose of solvent. Then the time variation of the galvanic converter signal is measured at a predetermined distance from the application point of the pulse with a dose of solvent, the values of the galvanic sensor signal are fixed at two-time points, and the diffusion coefficient is calculated. The measurement of the diffusion coefficient is carried out under the condition that the maximum of the galvanic converter signal E_max is reached, which equals to 0.75-0.95 of the maximum possible value of the given signal E_e, corresponding to the transition of the solvent from the area of the test material connected with solid phase to the area of free state. Time points τ₁ and τ₂ are fixed, at which the same values of signals of the galvanic sensor E₁ and E₂ from the range (0.7-0.9)E_e on the ascending and descending branches of the signal change curve in time are achieved, and the diffusion coefficient is calculated by the formula: ; ;where r₀ is the distance between the electrodes of the galvanic converter and the point of action of the solvent dose on the surface of the controlled product.;EFFECT: increased accuracy and speed of measuring the diffusion coefficient of solvents in the sheet products made of capillary-porous materials.;2 cl, 1 tbl, 3 dwg