Outdoors! Transparent acrylics in cultural heritage exposed to weather - case studies. Degradation phenomena and their possible causes

Transparent outdoor acrylics face more and stronger degradation factors and mechanisms than indoor museum objects, leading to severe degradation of the polymer, poly(methyl methacrylate, PMMA). In the paper at hand, six degradation phenomena (dp) of acrylic sheet are presented using the example of two listed monuments in Bavaria, Germany. The Felix-Wankel-Institute of 1961 in Lindau and the roof of the Olympic Sports facilities of 1972 and 1998 in Munich have construction elements with transparent acrylic sheets that show dp ranging between a cloudy, hazy but smooth surface and a white, opaque and crystalline surface that delaminates in flakes. The materials were analysed by means of Fourier Transform Infrared Spectroscopy and gas chromatography coupled with mass spectroscopy, pyrolysis and thermodesorption, which showed different compositions of the acrylics in the various buildings. By means of archival and literature research, the production techniques of the cast and thermoformed or stretch-formed acrylic sheets were reconstructed. Using the microscope and the polariscope, dp were characterised and mechanical stress was detected in the acrylic sheets. Possible factors and mechanisms that lead to the dp of PMMA are described in the literature and were examined by means of Gel Permeation Chromatography / Size Exclusion Chromatography.      «

Transparent outdoor acrylics face more and stronger degradation factors and mechanisms than indoor museum objects, leading to severe degradation of the polymer, poly(methyl methacrylate, PMMA). In the paper at hand, six degradation phenomena (dp) of acrylic sheet are presented using the example of two listed monuments in Bavaria, Germany. The Felix-Wankel-Institute of 1961 in Lindau and the roof of the Olympic Sports facilities of 1972 and 1998 in Munich have construction elements with transpare...     »