Cellulose nitrate degradation

SUva, M. (2006). Investigating cellulose nitrate degradation caused by fungal attack. In Postprints of The Future of the Twentieth Century-collecting, interpreting and conserving modern materials. Second Annual Conference Arts and Humanities Research Board Winchester 26-28 July 2005 (P. Garside, ed.) pp. 72-76. Archetype Publications. London. 

The solid-state NMR technique may also be used in cellulose derivatives to follow the degree of substitution and degradation of the chain e.g. as found for cellulose nitrate 16). Investigations on the composition of copolymers may also been done as examplared by celluloseacetate-butyrate given in Fig. 6, 20). Here, owing to relaxation differences the spectra cannot be used for elementary analyses, but for estimating the relative number of the components. 

Cellulose nitrate (Celluloid) 1850 Moulding material, paints, glues, coatings, photographic films, varnishes Camphor, phthalate esters High flammability and degradability, with production of nitrogen dioxide... 

To broaden the scope of his interests, he spent another year as a postdoctoral fellow in the Physics Department of Pennsylvania State University, working on the X-ray analysis of biological compounds. Equipped with an exceptionally broad and multidisciplinary education and experience, he proceeded to The Ohio State University, Columbus, Ohio, to work with Professor M. L. Wolfrom. His initial job was to investigate the ignition of cellulose nitrate, a project left over from World War II. In Fred s hands, this project was turned into an isotopic investigation of the biosynthesis and degradation of cellulose. At this time, there was very little known about the preparation of specifically labeled sugars, let alone the biosynthesis of... 

Cellulose acetate was developed in 1894 as a safe alternative to the combustible cellulose nitrate. It was made with acetic acid instead of nitric acid. It was not put into commercial production until the 1920s - after the First World War - when it was called rayon . If not kept in ideal conditions it can, in rare cases, degrade, giving off a smell of vinegar. 

The most susceptible of the plastics used to simulate organics is cellulose nitrate. Signs of instability and imminent degradation are patches of discolouration, surface crazing or blistering, weeping, and fumes. 

By careful nitration of cellulosic materials with nitric acid in the presence of phosphoric acid and phosphoric anhydride, a minimum of degradation occurs. " According to Schieber, the resulting cellulose nitrate may be separated by stepwise dispersion with successively richer solvent mixtures into a series of fractions of var3dng chain lengths. 

Since the properties and degradation reactions of plastics are usually influenced by their formulations and manufacturing processes, this chapter will first discuss those areas. Four plastics have been identified as being more vulnerable to degradation than others in museum collections cellulose nitrate, cellulose acetate, plasticised PVC and polyurethane foam. The most frequently seen... 

Metal ions. Copper ions act as catalysts to accelerate deterioration reactions of many polymers, particularly synthetic rubbers. Spectacle frames constructed from cellulose nitrate are often more degraded in the area around copper-containing screws and around the wires in the arms, than... 

The major causes of instability of cellulose nitrate are due to the products of hydrolytic, thermal and photochemical reactions. Degradation of the polymer is autocatalytic, that is, the products of breakdown tend to catalyse a faster and more extensive degradation reaction than the primary processes, if allowed to remain in contact with degraded cellulose nitrate. 

Some metals, notably copper, accelerate the rate of degradation of cellulose nitrate. Copper screws and arm wires of cellulose nitrate spectacle frames... 

Activated charcoal has been used successfully to dramatically reduce the rate of degradation of cellulose nitrate objects. The charcoal is treated with oxygen... 

The combustion of plastics is a complex process and only a brief overview is given here. A detailed description with data relevant to the combustion processes of common plastics may be found in specialist literature (Beyler and Hirschler, 2002). The plastics in collections which are infamous for their behaviour on combustion are cellulose nitrate and polystyrene. Cellulose nitrate is highly flammable, particularly when new and in the early stages of degradation, and burns explosively producing sparks (Figure 4.4). Polystyrene... 

---