A preliminary study on the physicochemical properties of pigmented StyBA/MMA emulsion films: The effect of thermal ageing

摘要

The effect of temperature on the physicochemical and mechanical properties of pigmented StyBA/MMA emulsion polymers containing synthetic organic pigments was studied. Thin films of artist's commercial paints from Liquitex (U.S.A.) and Rembrandt (NL) containing Azo yellow (PY3), diketo-pyrrolopyrrole red (PR264), phthalocyanine blue (PB15) and phthalocyanine green (PG7) were naturally dried and subjected to moderate artificial ageing at 60 degrees C and 55% RH and artificial soiling, to simulate thermally aged paints exposed to heat, humidity and dirt deposition. The changes in the paints' surface morphology were studied by Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS), Fourier Transform Infrared Spectroscopy in ATR mode (FTIR-ATR) and Differential Scanning Calorimetry (DSC) were used for their physicochemical characterization. In addition, mechanical testing was performed to investigate variations of the tensile properties. The study allowed the detection of deterioration patterns and defects, which include micro wrinkling and roughening of the surface due to the exposure of the inorganic fillers. Additionally, the extent of soil particles' penetration was observed to be dependent on the type and the mobility of the surfactant during and post artificial ageing. Physicochemical changes include increase of the polymer's T-g and decrease of the overall paint's physical and mechanical stability. Certain observations regarding the interaction of the components within the paint and the resultant resistance to thermal and mechanical stresses are discussed. (C) 2018 Elsevier Ltd. All rights reserved.