The effects of strain rate and temperature on commercial acrylic artist paints aged one year to decades

Abstract

Acrylic artist paints are viscoelastic composites containing a high molecular-weight copolymer, pigment and a variety of additives. The glass transition temperature of the latex binder is typically slightly below ambient conditions, giving mechanical properties that are strongly dependent on strain rate and temperature. In previous work, the viscoelastic behaviour of custom-formulated latex artist paints was reported for films with known volume fractions of pigment using data from uniaxial tensile tests at different strain rates and temperatures. Secant Young's modulus and failure strain mastercurves were constructed for each film through time-temperature superposition (TTS), allowing predictions beyond the experimental timescale at a selected reference temperature. A similar analysis is now presented for a small set of commercial artist paints tested at ages of one year and 27 years. Experimental shift factor values are reported with fits to the Arrhenius, WLF and Vogel Fulcher (VF) equations, along with a comparison to published data for acrylic polymers. The tensile results highlight a spectrum of properties that acrylic paints may exhibit-brittle glass to hyperelastic-depending on the conditions during deformation. Strong similarities are shown between products from different manufacturers, and the findings suggest a high degree of stability with age. A method for predicting failure as a function of strain rate and temperature is also presented, and the methodology gives a framework for investigating other artist materials and the factors influencing their mechanical properties.

Sistemas de limpieza gelificados para pinturas acrílicas en emulsión: una revisión de la literatura científica

“…En pinturas acrílicas se han reportado efectos similares en función de la T g y los cambios de temperatura y humedad relativa: las pinturas aumentan su rigidez conforme baja la temperatura, produciéndose cierta reducción de su capacidad de deformación. Cuando la temperatura se reduce por debajo de la T g , la película presenta un deterioro significativo de las propiedades mecánicas (menor estiramiento e incremento de la rigidez), mostrándose como un material frágil y quebradizo (Hagan et al 2015). En cuanto a la concentración de pigmentos, se considera que un volumen alto de partículas sólidas en una pintura puede producir películas poco cohesionadas, con poca resistencia y alargamiento hasta la rotura.…”

“…Similar effects have been reported in acrylic paints as a function of T g and changes in temperature and relative humidity: the paints increase their stiffness as the temperature decreases, producing an inevitable reduction in their deformation capacity. When the temperature is reduced below T g, the film significantly deteriorates mechanical properties (lower stretching and increased stiffness), showing itself as a brittle and fragile material (Hagan et al 2015). Regarding pigment concentration, it is considered that a high volume of solid particles in a paint can produce poorly cohesive films, with low strength and elongation to breakage.…”

After the paint has dried: a review of testing techniques for studying the mechanical properties of artists’ paint

“…Inorganic pigments also tend to be much stiffer than the binding media, also leading to a significant increase in the stiffness of the sample. Many of the studies focused on the effects of temperature [18,29,30,36,37,41,43,46,50,54,57] and relative humidity [15,29,30,34,36,37,41,43,44,46,52,57,59] on the stiffness of the sample. There is a general trend across all three binding media classes of increasing stiffness as the temperature of a paint decreases, shown in Fig.…”

“…Hagan et al varied the strain rate during their research on acrylic and oilbased paint systems to apply time temperature superposition (explained more fully in Sect. 3) to their results and observe the material response over a wider range of testing strain rates [18,19,46,50,54]. The studies also considered the effects of PVC as well as the shape of the pigment particles on the overall response of the pigment/binding medium composite sample using mathematical models focused on filler effects in a composite, highlighting the importance of understanding the PVC of a paint sample [19].…”

Ge-conservación Nº20

“…Similar effects have been reported in acrylic paints as a function of T g and changes in temperature and relative humidity: the paints increase their stiffness as the temperature decreases, producing an inevitable reduction in their deformation capacity. When the temperature is reduced below T g, the film significantly deteriorates mechanical properties (lower stretching and increased stiffness), showing itself as a brittle and fragile material (Hagan et al 2015).…”