Celluloid in museum collections is very unstable; therefore, heritage professionals carry out research studies dedicated to understanding its decay and prolonging its lifetime. This paper addresses the need to compare and select suitable analytical methods for that purpose. Thermogravimetric analysis coupled with Fourier transform infrared spectroscopy, evolved gas analysismass spectrometry, double shotgas chromatography/mass spectrometry, and gel permeation chromatography (GPC) were employed to characterize the emission of gasses (decay products) and measure the molecular weight and camphor (plasticizer) content from unaged, artificially, and naturally aged celluloid samples. A pioneer GPC setup for the quantification of camphor was introduced for the first time in this study. Results demonstrated that GPC was the most suitable method for assessing material changes due to degradation. Both setups , for measuring molecular weight and quantifying camphor, appear promising for assessing the effect of conservation treatments and investigating the heterogeneous degradation of celluloid objects in future studies.

Exposure of heritage plastics to solvents can cause several changes to their surface layers and bulk. The amorphous nature of certain plastics, particularly polymethyl methacrylate (PMMA), allows penetration and diffusion of low-molecular liquids, which can lead to swelling, cracking, plasticisation or stiffening, extraction and dissolution of polymer and additive components. Such phenomena compromise the visual characteristics, chemical and physical structure of heritage collections and remain, for the most part, unexplored. Research studies present contradicting evidence concerning the use of solvents and their safe application on PMMA. The main discrepancy is about PMMA being permeable to water or not. Alcohols have also triggered debates about whether they cause leaching and/or depolymerisation. This paper investigates the potential effects that selected free polar and non-polar solvents—employed in different media as cleaning systems—can have on PMMA after prolonged contact. The Hildebrand solubility theory was used to select solvents based on PMMA’s miscibility. The effects of deionised water, ethanol, isopropanol and petroleum ether are examined through a 30-day immersion study of PMMA via microscopic examination, weight change measurements, ATR-FTIR, peak height ratios, and NMR MOUSE. All four solvents extracted soluble components, i.e. unreacted residual monomer, and increased PMMA’s surface sensitivity to abrasions. Water and petroleum ether did not cause any measurable chemical or physical changes. Alcohols caused surface crystallisation and crazing, with isopropanol leading to stiffening and ethanol to plasticisation of the material. These effects, although extreme and absent in most routine cleaning timeframes, demonstrate the cumulative damage these solvents can potentially induce to PMMA.

This paper discusses the use of solvent-gel systems for the cleaning of poly (methyl methacrylate) (PMMA) surfaces. Aqueous polymer gel systems have been introduced to the conservation field with a particular focus on paintings, painted surfaces of wooden artefacts and stone. However, their application on plastics is very recent. Statistically designed experiments aimed to assess the efficiency and damage potential of materials constituting selected solvent-gel cleaning systems. The effect of the free solvents (deionized water, ethanol, isopropanol and petroleum ether), the hydrogel carriers (Agar, Pemulen™ TR-2, Carbopol® EZ 2-Ethomeen® C-25 and 80% hydrolysed PVAc-borax) and their combinations after 5 and 60 minutes of application time on PMMA surfaces, were evaluated through qualitative visual microscopic observation and SEM imaging, and quantitative weight change measurements. Visual observations revealed that the action of solvents (i.e. ethanol and isopropanol) was moderated by gellation (i.e. Agar), while other gel systems (i.e. Pemulen) were unsatisfactory. Results of gravimetric studies showed that most solvent-gels resulted in inconsistencies and large weight changes.

This article describes the development of a suitable Gel Permeation Chromatography method for cellulose nitrate plasticised with camphor (celluloid) found in cultural heritage. Current sample preparation and dissolution methods, apart from focusing on native, nonderivatised cellulose, require long preparation times, and often employ solvents that induce degradation. This study aims to develop a systematic method for sample preparation of cellulose nitrate that uses the least sample amount possible, is nondegrading, and can be applied on differently aged samples. This is investigated through identification of a suitable solvent system and a statistically designed experiment testing the critical variables affecting the analysis, namely sample condition, sample, and salt concentration (lithium chloride) in N,N-dimethylacetamide. The use of 0.1% sample was inadequate for analysis because it did not fully dissolve in any salt concentration, while the 0.3% negatively impacted the analysis with its high molecular weight distributions. The 0.2% cellulose nitrate in a solution of 0.5% lithium chloride in N,N-dimethylacetamide offered the most consistent and repeatable molecular weight data. This method miniaturised the sample as much as possible and is suitable for museum objects in various ageing conditions.