Abstract
In this work, we evaluate the water vapor transmission rate (WVTR), the permeability (P), solubility (S), and diffusion (D) coefficients of Paraloid B44, Paraloid B72, and Incralac coatings in the temperature range of 5–35°C. The Arrhenius function—diffusion activation energy and preexponential factor—has also been determined from the data: D_{B44} = 35.2;{text{cm}}^{2} ;{text{s}}^{ - 1} exp left( { - 25;{text{kJ mol}}^{ - 1} /{text{RT}}} right); D_{B72} = 9.5;{text{cm}}^{2} ;{text{s}}^{ - 1} exp left( { - 23;{text{kJ mol}}^{ - 1} /{text{RT}}} right); D_{text{Incralac}} = 622.8;{text{cm}}^{2} ;{text{s}}^{ - 1} { exp }left( { - 28;{text{kJ mol}}^{ - 1} /{text{RT}}} right). These resins are important coating materials, for example, for conservators to protect metallic artifacts, such as statues, against corrosion. Despite Paraloid B44 and B72 resins being considered as reference materials in conservation practice, that is, new coating materials (either water vapor retarders or transmitters) are often compared to them, there are no comprehensive data for the quantities describing the vapor permeability (P, S, D) of these materials. The measurements are based on the ISO cup-method using substrate/coating composite samples. The strength of this technique is that it can also be used when the coating is non-self-supporting; nevertheless, P, S, and D can be deduced for the coating layer itself, and it seems to be a standardizable procedure for comparative performance testing of coating materials. Paraloid B72 layers exhibited higher WVTRs—from 39 to 315 g m−2 day−1 as the temperature increased from 5 to 35°C—compared to Paraloid B44 and Incralac coatings—from 17 to 190 g m−2 day−1, respectively. The transmission rate parameters were also compared to the results of corrosion tests. Incralac was the most effective corrosion inhibitor, and the performance of the B44 was better than the B72, which is in good agreement with the transmission rate tests.
Highlights
Several kinds of polymeric resins are used in the art conservation practice, mainly in conservation and bonding
The resins were dissolved in acetone (Honeywell, assay minimum 99.5%) with different concentrations: 15 g Paraloid B44 and B72 dissolved in 100 ml acetone, and 40 g Incralac dissolved in 100 ml acetone, that is, 15 and 40 weight/volume percent (w/v %) solutions, respectively
The transmission rate data of the B44 and the Incralac are very similar, the Incralac provides better protection against corrosion. This is related to its Despite the fact that the Paraloid B44 and Paraloid B77 resins are reference materials, that is, new coating materials are often compared to them qualitatively, there are no comprehensive data for the quantities describing the vapor permeability (P, S, D) of these materials
Summary
Several kinds of polymeric resins are used in the art conservation practice, mainly in conservation and bonding. One of the most important tasks is the corrosion protection of cultural heritage.[1,2,3] Protective coatings made of these resins are applied to prevent corrosion.[4,5] It is, necessary to take into consideration the visual appearance and visualization of the objects in addition to corrosion protection. This principle poses a restriction on the applied coatings, mainly the type and the thickness of resins. Acrylic polymers, such as Paraloid B72, Paraloid B44, and Incralac, are largely used, for example, in art conservation because of their
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