Degradation of polymers in objects of museum collections at the micro-scale: a novel study with ATR-FTIR spectroscopic imaging
File(s)
Author(s)
Vichi, Alessandra
Type
Thesis or dissertation
Abstract
The characterisation of materials composing objects of museum collections is vital
for understanding the degradation mechanisms affecting them. Polymers of either natural or synthetic origin constitute a widespread class of materials commonly
found in these objects. Although natural polymers have been the subject of several
studies, aspects about their reactivity and degradation are still not fully understood.
Synthetic polymers have been more recently introduced in collections, causing new
and complex conservation issues to arise.
Over the last decade, Attenuated Total Reflection (ATR)-FTIR spectroscopic imaging
has emerged as a powerful method for the analysis of a broad range of materials.
FTIR spectroscopic imaging utilises a Focal Plane Array detector (FPA) that reveals
the spatial distribution of the compounds on the micrometre scale. Besides, this method is inherently non-destructive to the sample/objects analysed. However,
the application of the ATR-FTIR spectroscopic imaging approach in conservation science has been limited and its great potential has yet to be fully realised.
The aim of this thesis was to investigate degrading polymers in selected historical
samples and objects of museum collections with both macro and micro ATR-FTIR
spectroscopic imaging. The macro ATR imaging set-up revealed new insights into
the degradation of these samples, such as the formation of calcium soaps both in
parchment and leather book covers. Micro ATR-FTIR spectroscopic imaging allowed
a deeper understanding of mechanisms affecting the stability of cellulose nitrate
items to be obtained.
For the first time, depth profiling analysis of these polymeric materials using custom-designed apertures with both macro and micro ATR-FTIR spectroscopic imaging was applied. Depth profiling with micro ATR-FTIR imaging detected evidences of the degradation of plastic objects beneath the surface, without complex sample preparation steps. Furthermore, as with this method anomalous dispersion causing shift of strong bands in ATR spectra can be reduced, it aided the assignment of specific spectral bands of components in historical leather and parchment.
The results obtained provide useful information to improve methods for preserving objects of cultural heritage.
for understanding the degradation mechanisms affecting them. Polymers of either natural or synthetic origin constitute a widespread class of materials commonly
found in these objects. Although natural polymers have been the subject of several
studies, aspects about their reactivity and degradation are still not fully understood.
Synthetic polymers have been more recently introduced in collections, causing new
and complex conservation issues to arise.
Over the last decade, Attenuated Total Reflection (ATR)-FTIR spectroscopic imaging
has emerged as a powerful method for the analysis of a broad range of materials.
FTIR spectroscopic imaging utilises a Focal Plane Array detector (FPA) that reveals
the spatial distribution of the compounds on the micrometre scale. Besides, this method is inherently non-destructive to the sample/objects analysed. However,
the application of the ATR-FTIR spectroscopic imaging approach in conservation science has been limited and its great potential has yet to be fully realised.
The aim of this thesis was to investigate degrading polymers in selected historical
samples and objects of museum collections with both macro and micro ATR-FTIR
spectroscopic imaging. The macro ATR imaging set-up revealed new insights into
the degradation of these samples, such as the formation of calcium soaps both in
parchment and leather book covers. Micro ATR-FTIR spectroscopic imaging allowed
a deeper understanding of mechanisms affecting the stability of cellulose nitrate
items to be obtained.
For the first time, depth profiling analysis of these polymeric materials using custom-designed apertures with both macro and micro ATR-FTIR spectroscopic imaging was applied. Depth profiling with micro ATR-FTIR imaging detected evidences of the degradation of plastic objects beneath the surface, without complex sample preparation steps. Furthermore, as with this method anomalous dispersion causing shift of strong bands in ATR spectra can be reduced, it aided the assignment of specific spectral bands of components in historical leather and parchment.
The results obtained provide useful information to improve methods for preserving objects of cultural heritage.
Version
Open Access
Date Issued
2018-05
Online Publication Date
2020-11-30T07:00:20Z
2020-12-09T15:07:04Z
Date Awarded
2018-12
Copyright Statement
Creative Commons Attribution NonCommercial Licence
Advisor
Kazarian, Sergei G.
Sponsor
Imperial College London
Publisher Department
Chemical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)