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Chemical analyses of glycol-modified copolyester surface abrasion: Beyond the scratches from a mechanochemistry perspective

Abstract:

Thermoplastic abrasion constitutes an important consideration for not only improving the application lifetime of polymeric materials but also reducing the volume and impact of solid waste. This study explores the abrasion characteristics of a series of glassy glycol-modified polyesters without focusing exclusively on mechanical properties. Here, we demonstrate how changes in chemical characteristics, which are discernible by surface-sensitive spectroscopic methods, can be used to monitor the abrasion process, elucidate molecular-level mechanisms and differentiate the three polyesters under investigation on the basis of their abrasion response. Moreover, we introduce the carboxyl index discerned from Fourier-transform infrared spectroscopy in attenuated total reflection mode and utilize this novel index, in conjunction with the carboxyl bond content ascertained from X-ray photoelectron spectroscopy, to quantitatively describe polyester surface degradation. Comparison of several surface-related degradation mechanisms upon appropriate data normalization to account for material-specific abrasion properties or other relevant exposure conditions yields surprisingly similar responses, implying that polymer abrasion is an example of a mechanochemical process wherein both mechanical degradation and distinct chemical changes influence the abrasion-driven evolution of surface properties.