Evaluation of Cellulose Ethers for Conservation

Table of Contents
Foreword
Chapter 1
Chapter 2
The Structure of Cellulose
Manufacture of Cellulose Ethers
Comparison of Cellulose Ethers with Cellulose
Specifications and Typical Properties of Cellulose Ethers
Solubility of Cellulose Ethers
Influence of Degree of Substitution (DS)
Solubility of Ethylhydroxyethylcellulose
Stability of Cellulose Ethers as Reported in Manufacturers’ Brochures
Effect of pH on Cellulose Ether Solutions
Degradation by Acid
Initial pH
Properties of Films
Mechanical Properties
Equilibrium Moisture Content
Solubility/Temperature Relationships
Effect of Carboxyl Groups (Carboxymethylcellulose)
Viscosity/Temperature Relationships
Rheological Behavior of Solutions
Properties Not Related to Hydrophilicity
Chapter 3
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11
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37 Standards of Stability
Resistance to Photochemically Induced Degradation
Resistance to Thermally Induced Degradation
Microbiological Resistance
Behavior of a Generic Chemical Class of Commercial Products
Upgrading
Standards of Thermal Stability
A Simple Test of Thermal Aging
Effect of Exposure to Light
Proposed Test of Thermal Stability
Controls
Objective Measurement of Discoloration
Weight Loss
Viscosity Loss
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1
3
3
4
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5
9
Introduction
Objectives
AATA Survey
Questionnaire to Conservators
Reported Aging Studies on Cellulose Ethers
Properties of Cellulose Ethers
Chapter 4 Summary of Previous Investigation Supported by the National Museum Act
Introduction
Measurement of Reflectance at 500 nm
Principal Test Procedure
Results
Ethylcellulose (EC)
Hydroxyethylcellulose (HEC)
Carboxymethylcellulose (CMC)
Hydroxypropylcellulose (HPC)
Methylcellulose (MC) and Hydroxypropylmethylcellulose (HPMC)
Oxygen Uptake
Conclusions
Chapter 5
Chapter 6
Description of Materials and Experimental Procedures
Materials
Experimental Procedures
Weight Loss and Color Change of Powders
Weight Loss and Color Change of Films on Glass
Color Changes of Cellulose Ethers Applied as Paper Size
Peroxide Determination
Viscosity Determination
Intrinsic Viscosity
Brookfield Viscosity Determination
Exposure to Light
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Results and Discussion
Discoloration and Weight Loss
Thermal Aging of Powders at 110 °C
Thermal Aging of Powders at 90 °C
Films on Glass After Aging at 90 °C
Microscopic Examination
Color Change
Color Change on Sized Paper
Conclusions
Peroxide Formation in Cellulose Ethers
Thermal Aging at 90 °C
Cellulose Ether Films Aged Under Fluorescent Lamps
Photochemical Aging of Cellulose Ether Powders at 90 °C
and 50% Relative Humidity
Peroxides in Old Samples of Cellulose Ether Powders
Decomposition of Peroxides at 90 °C
Conclusions Regarding Peroxide Formation
Fall in Intrinsic Viscosity of Cellulose Ethers During Accelerated Aging
Powders Thermally Aged at 90 °C
Exposed Under Fluorescent Lamps
Brookfield Viscosity of “Shelf-Aged” Cellulose Ethers
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Brookfield Viscosity of Aged Cellulose Ethers
Relationship Between Intrinsic Viscosity, Brookfield Viscosity, and Degree of
Polymerization
The Brookfield Viscosity of Solutions of Cellulose Ether Powders Aged at 90 °C
Hydroxyethylcellulose (HEC)
Hydroxypropylcellulose (HPC)
Methylcellulose (MC)
Hydroxypropylmethylcellulose (HPMC)
Carboxymethylcellulose (CMC)
Relative Stability of Several Cellulose Ethers Commonly Used by Conservators
Fall in Viscosity
Change in Inverse of Viscosity
Photochemical Stability: Brookfield Viscosity Films Exposed Under Daylight
Fluorescent Lamps
Hydroxypropylcellulose
Methylcellulose
Carboxymethylcellulose
Chapter 7
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Appendices
Conclusions
Cellulose Ethers Considered Unsuitable for Long-Term Applications
Findings with Respect to Hydroxypropylcellulose
Cellulose Ethers of Intermediate Thermal Stability
Cellulose Ethers with Excellent Long-Term Stability
Need for Testing
Final Remarks
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A: Cellulose Ethers in AATA
B: Questionnaire on the Use of Cellulose Ethers by Conservators
C: Cellulose Ethers Available to Conservators
D: Technical Notes on Methylcellulose and Carboxymethylcellulose
E: Enzymatic Degradation of Cellulose Ethers
F: Peroxide Formation in Ethylcellulose
G: Complete Characterization of Cellulose Ethers: Distribution of Substituents
H: Analysis of Cellulose Ethers
I: The Relationship of Molecular Weight and Intrinsic Viscosity
References Cited
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Supplementary References
Index
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