The paradox of conserving plastics: a contemporary challenge

Plastic objects nowadays surround us in many ways, enough to consider these materials as modern par excellence. Plastics can be defined as semi or fully synthetic polymers modified with various typologies of additives designed to improve several properties of the final product. Additives, as well as polymerization and processing processes, have great influence on the resulting products, making possible to produce extremely versatile materials which can be shaped as three-dimensional objects, films, foams, fibers and much more. Aside from the environmentally non-friendly heritage, which disastrous consequences are well known, another kind of heritage made of plastics has been recently drawing the scientific community attention: the cultural one. As a matter of fact, artists worldwide have been choosing plastics to express their creativity since the beginning of XX century, thanks to the incredible adaptability of these modern materials. Nowadays, objects made of synthetic polymers are present in numerous art collections worldwide. However, differently from traditional ones, these manmade materials have not yet been extensively studied regarding their long-term durability in outdoor and indoor museum environments. It is indeed well known how plastics, especially the semi-synthetic ones, are susceptible of fast weathering processes which often have dramatical consequences, even when the artworks are not exposed to extreme environmental conditions. Moreover, the juxtaposition of different materials is often part of the artist’s design and contributes to the fast deterioration of plastics and surrounding components. Collecting and caring for contemporary artworks made of plastics are today marked as priorities for museums and conservators. Indeed, it is nowadays recognized by conservators and scientists worldwide how the conservation intervention must come along with a deep knowledge of materials and techniques chosen by the artists, in order to identify the best strategies for the restoration and conservation of cultural heritage. The lack of comprehension of materials and their degradation patterns may, in fact, easily lead to inaccurate or even wrong conservative interventions which can affect, often irremediably, the artworks. The aim of this PhD work was to study different plastics as constituents of contemporary artworks dated between 1966 and 1997 to understand materials and ageing pathways. One of the goals of this work was to provide the conservators with a complete overview about the ageing behaviors of synthetic and semi-synthetic polymers in order to support the restoration and to identify suitable conservation conditions. To achieve this purpose, the Physical and Chemical Sciences department of L’Aquila University has started a fruitful collaboration with the Istituto Centrale per la Conservazione ed il Restauro (ISCR) of Rome, the Scuola ENAIP of Botticino (Br) and several museum institutions as well as the Center for Research in Biological Chemistry and Molecular Materials (CIQUS) of Santiago de Compostela. The astonishing versatility of plastics often corresponds to complex compositions, which required a multi-analytical approach in order to obtain a complete set of information. Such approach was mostly based of molecular spectroscopy, as both FTIR (Fourier transformed infrared) and Raman spectroscopy allowed to get qualitative data and to determine functional groups in the molecules studied. Moreover, optical and scanning electron microscopy (SEM) in conjunction with energy dispersive spectroscopy (EDS) and portable XRF were used to study both macro and micro morphology of the surfaces and to get fundamental information on the inorganic components. These analytical techniques were applied successfully to the study of the materials, providing an interesting insight on the conservative conditions of the artworks investigated and often highlighting degradation products and inaccurate conservation interventions