Characterization of U-matic videotape deterioration by size exclusion chromatography and pyrolysis gas chromatography/mass spectrometry and the role of adipic acid

Magnetic tapes contain information that are an important part of our cultural heritage and must be preserved for further generations. However, they are unfortunately threatened due to the chemical deterioration of the magnetic layer. In order to develop a tool to assess the tape collection condition, 300 U-matic videotapes from the Institut National de l’Audiovisuel (INA) collection dated from 1975 to 1995 were analysed by different analytical techniques. The authors were attempting to constitute a group of 29 reference tapes representative of the INA collection using various analytical testing. The focus of this study was on hydrolytic tape stability using binder polymer identification and ageing tests. It was found that PET based polyester–polyurethane binders demonstrated a higher hydrolytic stability than binders made of poly(butyleneadipate)/polyurethane, which are more susceptible to fast deterioration. The authors examined the role of adipic acid in the hydrolytic degradation process. For such tape binders, a deterioration assessment method could be based on monitoring the adipic acid concentration and adipic acid rich oligomeric fragments in the binders. A method for measuring the amount of polymeric fragments in the low molecular weight region is proposed.