Abstract

CASTELLANOS, Isabel Cristina et al. Monitoring via Infrared Spectrometry and Rheometry of a Vulcanization-Like Process of Chewing Gum Waste. Ing. Investig. [online]. 2023, vol.43, n.2, pp.1-.  Epub Apr 17, 2024. ISSN 0120-5609.  https://doi.org/10.15446/ing.investig.99467.

Once chewed, chewing gum becomes a disposable and non-degradable cumulative residue that causes environmental, economic, and social problems. Collecting and treating chewing gum waste until its properties are adapted for some profitable use will generate environmental and economic savings. In this work, chewing gum waste was collected, sanitized, and subjected to a laboratory-scale rubber vulcanization-like process with sulfur. The evolution of the process was monitored via sequential measurements of torque and the acquisition of a series of ATR-FTIR spectra on the raw and resulting material of aliquots isolated from the reaction medium every 10 minutes for 4 hours. The absorbance values of the signals in the series of ATR-FTIR spectra were normalized and subjected to a descriptive statistical analysis, which allowed detecting intensity variations in bands attributed to carboxylate, as well as a slight decrease in the intensity of the bands attributed to hydroxyl, carbonyl, methylene in alpha to carbonyl, and other CHn groups in aliphatic fragments. These intensity changes and the trend of rheometric measurements during the process (vulcanization curve) evidenced that chewing gum waste did indeed react. Its vulcanization process had an absolute cross-linking maximum 5,15 minutes into the process and caused a remarkable increase in the torque of the resulting material; the Shore A hardness changed from 20 to 95 units, and the density varied from 1 280 to 1 510 kg/m3. These findings hint at an alternative treatment to reduce environmental pollution and revalue chewing gum waste.

Keywords : chewing gum waste; vulcanization; rheometry; mid-infrared; ATR-FTIR spectroscopy.

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