Chemistry of the Interactions of Acetaldehyde Scavengers for Poly(ethylene terephthalate)

The acetaldehyde (AA) scavenging mechanisms of anthranilamide, metaxylenediamine (MXDA), and alpha-cyclodextrin were investigated through a combination of proton nuclear magnetic resonance (H-1-NMR) and mass spectrometry techniques. AA was found to react with the amide and amine groups of anthranilamide to produce a two-ring structure with water as a byproduct. MXDA possesses two terminal, primary amines that make it difunctional. The aldehyde group of AA reacts with each primary amine to create an imine group and water. The imine groups were found to act as chromophores, supporting the results of previous work with poly (ethylene terephthalate). The AA scavenging mechanism for alpha-cyclodextrin was determined through concentration dependent NMR experiments. As the concentration of alpha-cyclodextrin was increased, the chemical shifts of AA's protons increased until a saturation point was reached at a molar ratio of one to one. This indicates that each alpha-cyclodextrin accommodates one AA molecule through hydrogen bonding and a size-enclosure mechanism. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4191-4200, 2013