The Influence of Solvent Vapors on the Rheological Properties and Permeability of Butadiene–Styrene Films Studied by Quartz Acoustic Gravimetry

Resumo

Rheological properties and diffusion permeability of butadiene–styrene film in vapors of organic solvents were studied in both the equilibrium and nonequilibrium states. The investigations by quartz acoustic gravimetry showed that, under the influence of butadiene, acetone, ethanol, dimethylformamide and water vapors, the shear modulus and mechanical losses of the film decreased. This effect was inversely proportional to distance R_a between the centers of the Hansen solubility spheres of a polymer and solvent. The extent of this decrease for R_a = 13 MPa^0.5 is significantly higher than that within a range of R_a ≥ 13 MPa^0.5. The dependences describing the changes in the shear modulus coincided qualitatively with that for the swelling degrees versus distance R_a. Under the influence of vapors, the kinetics of frequency changes in a “resonator–film” system can be described by two exponents: the first short exponent characterizes the permeability of a polymer film before the exposure in vapors and during the first minutes of the process, and the second one is one to two orders slower and covers a subsequent period. The time constant of the short exponent is proportional to R_a.