The Impact of Fillers on UV-Aging of Rotomolded Polyethylene Items: A Case Study on Ignimbrite Dust, Arundo donax L. Fibers, and Their Combination

Different composites of polyethylene and two fillers (ignimbrite dust and <i>Arundo donax</i> fibers) were obtained by rotational molding. Both fillers were also combined among them to produce hybrid composites. The blends, prepared by dry-blending, were later rotomolded to determine the effect of such fillers into the tensile properties of the materials, before and after subjecting them to accelerated weathering on a UV chamber for up to 500 h. No significant differences are observed in the mechanical behavior of the different sample series, regardless their type or ratio of filler (5 or 10% by weight), due to the modifications only taking place on the sample surface and the rotomolded items having a thickness of nominally 4 mm. The carbonyl index was obtained from the FTIR spectra, determining an increase in this parameter with irradiation time. The samples with the <i>Arundo</i> fibers exhibit a lower carbonyl index, showing the potential stabilization effect of this lignocellulosic filler against UV, while the composites with the mineral powder tend to increase the oxidation of the samples when included at high loadings (10%).