S Stephen, T Shah, AE Pillay and E Siores
Keywords: ICP-MS, SEM, polymers, metal leaching, laser ablation
Abstract: In this study polypropylene samples doped with varying levels of Mg, Ti and Zn were subjected to leaching under different pH conditions for a period of six months. Laser ablation and SEM techniques were used to investigate the samples in order to verify the presence of metals in the matrix. The leachates were subsequently analyzed by ICP-MS and the data were processed to compute the reaction kinetics. It was found that for all three metals of interest the leaching process was governed by first-order kinetics. The rate constant for the leaching reaction was noticeably low denoting that metal migration from polypropylene is protracted and does not particularly constitute a potential hazard. Significant differences between the leaching behavior of Ti and Mg/Zn from the polypropylene matrix were observed. The mechanism of the leaching process was considered to be analogous to aqueous degradation of polymorphic crystal structures of the embedded dopants.
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