THE DEGRADATION OF POLYESTER POLYURETHANE: PRELIMINARY STUDY OF 1960s FOAM-LAMINATED DRESSES

Abstract

Four 1960s dresses that form part of the costume collection at the Museum of London (UK) are made from a laminated fabric, which consists of a layer of foam sandwiched between two knitted fabrics. As the foam deteriorates, it breaks up into small particles that escape through the knitted fabric as dust. The foam was identified as one of two types of polyurethane (PUR): polyester polyurethane or PUR(ES). The foam dust was found to be acidic and accelerated corrosion tests confirmed volatile organic acids as end-products of PUR(ES) foam breakdown. Accelerated aging tests, performed on samples of new PUR(ES) in a variety of environmental conditions, suggest that hydrolysis rather than oxidation is the dominant mechanism for deterioration and that the rate is slowed at low relative humidity. The authors suggest that objects containing PUR(ES) should be stored at low relative humidity and away from acid-sensitive items, and emphasize the importance of correct identification of this synthetic material in museum collections.