FT-IR spectroscopy is often used in industry to test the decay rate of isocyanate (NCO) in a freshly applied adhesive because unreacted aromatic NCO molecules can migrate through laminated packaging into food to react with water molecules, generating carcinogenic primary aromatic amines that are harmful to humans and pets alike. Transmission spectroscopy is routinely used in industry; however, the coating weight must be carefully controlled to ensure consistent pathlength. This requires preparation techniques such as screen printing that adds complexity and requires user know-how. ATR spectroscopy would eliminate this sample preparation owing to its fixed pathlength; however, this ties up the expensive ATR accessory for the duration of the experiment and can be difficult or impossible to clean once the glue is set. Arrow eliminates these difficulties and opens the door to the use of ATR spectroscopy in more applications than ever before.
Analysis of packaging adhesives with the Arrow ATR