Analyses and findings of unusual substitute materials in a raincoat from WWII

Due to the coating materials used, historic raincoats are vulnerable to degradation and rarely survive long periods of time. The investigated raincoat dating from 1943 is no exception—the coating is unusually stiff and flaking off in areas around folds and cracks. Study into its material composition can contribute to important knowledge of the availability of materials for waterproof clothing during the time of the German occupation of Denmark (1940–1945) when the usual materials for raincoats, cotton fabric and rubber, were in short supply. Optical microscopy and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) identified the fabric to consist of rayon staple fibres and paper yarn, and the coating to be based on cellulose nitrate (CN) lacquer and an unknown plasticiser. Though the results are atypical for a raincoat, they are in good accordance with the raw materials available in Denmark in 1943. Analysis by matrix-assisted laser desorption-ionisation mass spectrometry (MALDI-MS), and 1H and 13C nuclear magnetic resonance spectroscopy (NMR), identified the plasticiser as poly(1,3-butylene) adipate. Powder X-ray diffraction (PXRD) moreover identified the pigment as titanium white of the anatase form. By historical discussion, this study argues that IG Farben is the likely producer of poly(1,3-butylene) adipate, even though the first known marketing of the plasticiser is from 1986 where the Swiss firm Ciba-Geigy introduced poly(1,3-butylene) adipate as a plasticiser for PVC cling films under the tradename Reoplex® 346. The results give an interesting insight into the use of substitution products during WWII and provide new information on polymer science of the time.