The sorption process of methyl methacrylate (MMA) -acrylamide (AM) copolymer (MMA/AM=0.95/0.05 in mole ratio) was followed up by the decrease of ζ-potential with time. The activation energies of sorption obtained from the Arrhenius plot of the rate constants were ΔE1z=-5.62 kcal/mol (T<<Tg) and ΔE2z=7.19 kcal/mol (T>>Tg) where Tg is the glass transition point of the copolymer (50.7°C). On the other hand, from the Arrhenius plot of the diffusion constants obtained directly from sorption experiment, ΔE2s (T>>Tg) was 1.88 Kcal/mol and sorption amounts were about 10 times as large as those of ordinary hydrophobic polymers. The authors compared these results with those obtained from sorption of methyl methacrylate-N- (hydroxymethyl) acrylamide (MAM) copolymer (MMA/MAM=0.95/0.05 in mole ratio) and discussed the effect of NH2 and NHCH2OH groups in MMA copolymers on sorption process.
This paper deals with the influence of solvent composition upon viscoelastic properties of paint films. The samples of various solvent-diluent ratio in the solvent composition were prepared for typical nitro-cellulose lacquer, typical acrylic lacquer, acid catalyzed melamine alkyd resin paint, alkyd resin paint, polyamide resin cured epoxy resin paint and melamine alkyd resin paint. Viscoelastic properties of the films were determined by the measurements of stress-strain relation and dynamical viscoelasticity. Meanwhile, degree of swelling of the films was measured and also the retained solvent in the films were measured by gas chromatography. Experimental results are summarized as follows. (1) It was generally found for air drying type paint that when the concentration of diluent increased, values for dynamical modulus E and stress σ decreased and breaking elongation ε showed maximun value. Influence of the solvent composition was not found for nitrocellulose lacquer due to the rigidity of the nitrocellulose molecule. (2) Although acid catalyzed melamine-alkyd resin paint gave apparently the similar results as (1), the mechanism is not the same. The main reason is in the difference of the cross-link density of the films. (3) As a rule, viscoelastic properties of baking type paint were not affected with the solvent composition. (4) The results described above were considered from the viewpoint on the state of vehicle polymer in the solution.