The effects of the weathering methods on the properties of the ABS, ASA and PMMA polymers

In this study, the effects of natural and accelerated weathering methods on the mechanical and color properties of three commercially available thermoplastic polymers used in the automotive industry were investigated. The polymers are poly (methyl methacrylate) (PMMA), acrylonitrile butadiene styrene (ABS) and acrylonitrile styrene acrylate (ASA). All the samples were exposed to natural weathering conditions directly during one year (between November 11th, 2019 and November 11th, 2020) in Bursa, Turkey. This pioneering research was carried out for the first time in Turkey. The chosen accelerated weathering methods against the natural weathering are by Xenon-arc lamp and UV lamps, respectively. Statistical evaluation of data obtained from the tensile stress and the tensile strain curves was performed by Student–Newman–Keuls (SNK) test. The determination of color change values was carried out either visually by the grey scale assessment or spectrophotometrically. The correlation coefficients amongst weathering methods were investigated for visual and instrumental assessment methods with the Kendall's correlations method. PMMA samples showed the best performance for all three different weathering methods. While the fastest degradation occurred in ABS and ASA samples, which contained butadiene monomer, no remarkable change was observed in the tensile stress of all samples. However, the tensile strain values of weathered samples decreased. This shows that the polymers harden when exposed to either natural or accelerated weathering by photo-oxidation reaction. The correlation coefficients of the assessments of the color change by the spectrophotometer are lower than the ones by the grey scale. Therefore, the correlation coefficient of the assessments of the color change by the grey scale was taken into account. There was a high correlation between natural weathering and the accelerated weathering by Xenon-arc lamp. The correlation coefficient was 0.755. On the other hand, the correlation coefficient between natural weathering and the accelerated weathering by UV fluorescent lamps was 0.591.