Conservation Science

186 Chapter 8 War designs were marketed in large numbers as housewares. They developed a long-lasting image as low value, low qu ...

Plastics 187 objects are collected for the same reasons. In this way, museums act, often unintentionally, as storage depots for ...

188 Chapter 8 degradation reactions and the possibilities for conserving these plastics will be presented in this chapter. 2 The ...

Plastics 189 They are made by esterifying cellulose, in the form of either cotton linters or wood pulp. Cotton linters, the shor ...

190 Chapter 8 The acetylation of cellulose to cellulose acetate involves three stages, pre- treatment of the cellulose, acetylat ...

Plastics 191 The process used to produce more than 80% of commercial PVC polymers is suspension polymerisation. An aqueous suspe ...

192 Chapter 8 To produce polyurethane foam, water is added to the polyol and isocyanate starting materials. The water molecules ...

Plastics 193 For example, raw PVC polymer is a brittle, inflexible material with rather limited commercial possibilities. Attemp ...

194 Chapter 8 lubricant may act as a plasticiser once incorporated into a formulation. The major requirements for additives in p ...

Plastics 195 may be converted into films or sheets, solid or hollow three-dimensional forms, fibres and foams. Early plastics, l ...

196 Chapter 8 and instrumental techniques. Before examining plastic objects, it is helpful to have as much historical informatio ...

Plastics 197 Universal Indicator paper at the mouth of the tube. The results may be interpreted as: ●pH 1–4 (Acidic): cellulose ...

198 Chapter 8 as shown in Figure 1. The quality of spectra is dependent on intimate contact between the diamond crystal and the ...

Plastics 199 Unknown plastics may be identified either by comparing spectra with those from reference or known samples; or with ...

200 Chapter 8 of the earliest commercial plasticisers, sublimes at ambient temperatures and so was lost rapidly from cellulose n ...

Plastics 201 by cleavage of the N
O bonds joining the cellulose ring that are the weakest bonds in the molecule. Nitrogen dioxid ...

202 Chapter 8 from the 1930s accelerate degradation of surrounding cellulose nitrate and are, in turn, corroded by the nitric ac ...

Plastics 203 degradation of PVC takes place is complex. In general, it comprises one major reaction; the evolution of hydrogen c ...

204 Chapter 8 to the touch and embrittled. Low-density polyethylene is an effective absorber of oily materials, including plasti ...

Plastics 205 processes. Exposure to moisture, heat and light leads to polyurethanes’ degrad- ation by hydrolysis. Degradation re ...