260: FTIR differentiation of polyethylene and polypropylene toy building blocks by brand

Abstract: Plastics are ubiquitous in modern society, with applications spanning packaging, construction materials, and consumer goods. Consumer goods such as plastic toys are of particular concern for human health and environmental safety due to the vulnerability of the target audience and the low recycling rates for these products. Although modern toy production in the United States and Europe is highly regulated, older (second-hand) or imitation samples may not meet these standards, posing an increased risk to consumers. Plastic building blocks provide a representative model system because of their decades-long popularity, use of multiple polymer types, and presence of competing brands. In this study, Fourier transform infrared spectroscopy (FTIR) with attenuated total reflectance (ATR) was used to collect spectra from commercial plastic building blocks. Samples composed of polyethylene and polypropylene were emphasized because their relatively simple FTIR spectra enable streamlined analysis and comparison. Principal component analysis (PCA) was applied to the FTIR spectra to differentiate samples by manufacturer, color, and piece type. The results highlight spectral features that can be used to distinguish polymer composition among building block brands, enabling assessment of the safety, quality, and material integrity of these plastic products.