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Filling the Gaps: Effects of Organic Acids on Objects in Museums, Libraries
and Archives
Part I: Parchment, Leather, Cellulose
Rene LarsonDorte V.P. SommerKathleen Mühlen AxelssonMarianne Odlyha
Myung-Joon JeongKyujin AhnAntje Potthast
Outline
The Approach Aging and Analytics
Volatiles - what happens with: Parchment, Leather and Cellulose
From chemical analysis to museum From chemical analysis to museum reality: How to translate data into practical applications
Conclusions
The Approach
(Accelerated) Aging / Exposure
Acetic acidFormic acid
TemperatureHumidityTime ….
Aging / Exposure
Parchment (p)
Historical parchment (hp)
Mimosa tanned leather (m)
Sumac tanned leather (s)
Historical leather (hl)
Historic rag paper
Book paper
Whatman paper
Newsprint paper
1- 16 weeks Several months up to 1.5 years
(Accelerated) aging
Acetic acidFormic acid
TemperatureHumidityTime ….
The Approach
(Accelerated) aging
Acetic acidFormic acid
TemperatureHumidityTime ….
aging
Tim e (m in)5 6 7 8 9 10
Abso
rbance
(m
Au)
0
10
20
30
40
Lyx
Ara
Xy
l
Rib
Gu
l
Ta
lG
lc Ma
nId
o
All
Alt
Ga
l
20 22 24 26 28 30 32 34 36 38 40
a.u
.
Retention time [min]
RI Fluoreszenz
MALLS 90°
ANALYSIS
The Approach
T im e (m in)5 6 7 8 9 10
Abso
rbance
(m
Au)
0
10
20
30
40
Lyx
Ara
Xyl
Rib
Gu
l
Tal
Glc M
an
Ido
All
Alt
Gal
20 22 24 26 28 30 32 34 36 38 40
a.u
.
Retention time [min]
RI Fluoreszenz
MALLS 90°
Retention time [min]
ANALYSIS
Translate analytical data into practically relevant measures
Reference immediately after exposure after exposure, degassing 2 weeks
Organic acids and parchment: What happens ?
parchment 1 week Swelling and pH
Extreme swelling after One week of exposure degassing shows some deswelling, but still drastic morphological changes remainDegassing only raises the pH less than one pH unit in both cases. Around pH 4 risk for extreme swelling and deswelling in moist humid condition
3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0.55
historic parchment 16 weeks
parchment 1 weekno degassing
historic parchment 1 week average historic parchment
historic parchment 1 weekno degassing
parchment 8 weeks
thic
kness
[m
m]
pH
parchment 16 weeks
average parchment
Swelling and pH
pI
Organic acids and leather:
What happens ?
Color based on CIE L*a*b*
color changes (RED) acid induced condensation of tannin stiffer, less flexible surface
Damage assesment of collagen : From macro to nano
Nano-levelMacroscopic testing
Triple helices held by cross links to give a structure with regular banding D=67nm and image as seen by Atomic Force Microscopy
Macro Nano
undamaged
1.5
2
2.5
Dis
pla
ce
me
nt
D (
%)
Extension vs RH%
Damage assesment of collagen : From macro to nano
0
0.5
1
20 30 40 50 60 70 80
RH (%)
Dis
pla
ce
me
nt
D (
%)
Acid exposed new parchment (more damaged) has lowerextension and lower rate of expansion than unexposed parchment
damaged
Gelatinisation
5µmx5µm 5µmx5µm
AFM cantilever
tip
AFM for damage assessment of parchment
Four damage categories defined by AFM:
• Almost intact D-spacing• Local collapse of D-spacing• Wrinkle formation• Gelatinisation
sample surface tip
5µmx5µm
AFM and µDMA: Mechanical testing on the nano-level
Damaged gelatinised surfaceAcetic acid exposure
Peak broadening indicative of
damage and gelatinisation.
Acid induced damage: two weeks acetic acid vapour at 75%RH
Micro-Thermal Analysis
L.Bozec and M.Odlyha 2011 Thermal denaturation studies of collagen by micro-thermal analysis and AFM Biophysical Journal 101:228-236
C–Collagen like G-Gelatine like
5µmx5µm 5µmx5µm
Ref A
Organic acids and parchment: AFM
Intact Collagen (triple helix)
Collagen disordered shrinkage Ts ↓
Ref A
6 weeks
Unexposed new parchment: some damage (lower left)
2 weeks HAc.Gelatinisationand loss of D-banding
Atomic force microscopy
J de Groot Ph.D thesis & W.Zhou M. Res Birkbeck, University of London
In situ measurementsRoyal Library, Copenhagen
In situ measurements, Royal Library, Copenhagen
Outside box HAc (µg/m3) YearsNovember 2011 Royal Library 107.9 309January 2012 MEMORI 213.3 156June 2012 MEMORI 156.5 213
Average 159.2
Years of exposure to reach 400 mg/m3 of acetic caid
Average 159.2
Theoretical years of in situ exposure to obtain a decrease of pH from 7 to 4 in historical and modern parchment: ≈ 400 years.
The acidification of parchment with a pH below 5 may be faster when all calcite buffer present has been consumed.
How to quantify these changes ???
Hydrolysis and the concept of Half-life DP ?
? years
Hydrolysis and the concept of Half-life DP ?
The time (in years) until only 50% of the original degree of polymerization (DP) of cellulose remain
? years
Natural Aging : up to several 100 years at room T
Artificial Aging : Several decades ~ several 100 daysat elevated T
1.80
Degradation
The concept of Half-life DP ? First measure DP !
10,000 100,000 1,000,000-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
log
dif
fMw
Molar mass [g/mol]
0
5 days
15 days
30 days
The rate of chain scission(Ekenstam equation)
Kt= 1/DPn – 1/DP0
different Temperatures
The concept of Half-life DP ? Extrapolate toroom temperature
-14
-12
-10
50C
21C
65C80C
100C
No Acid
Acetic acid (14.5 mg/m3)
Formic acid (14.5 mg/m3)
8
10
12
14
Ag
ein
g t
ime (
days
)
50C
R2=0.9987
62 years
172 years
103 y.
21C65C80C100C
No acid
Arrhenius plots0.00260.0027
0.00280.0029
0.00300.0031
0.00320.0033
0.00340.0035
-20
-18
-16
-1421C
ln k
1/T
Extrapolation to roomtemperature
0.00
26
0.00
27
0.00
28
0.00
29
0.00
30
0.00
31
0.00
32
0.00
33
0.00
34
0
2
4
6
8
Ag
ein
g t
ime (
days
)T-1 (K-1)
Calculate years forhalf-life DP
The concept of Half-life DP ? Considerdifferent acid concentrations and papers
100
Whatman
Half-life DP for different acid
concentrations and different paper types
10
15
20
y=2.58Ac*10-1
100°C 80°C 65°C 50°C
1d
ayA
Cn
0 10 20 30 400
20
40
60
80
Half
-lif
e D
P [
Yea
r]
Acetic acid [mg/m3]
Whatman
0 10 20 30 40 50 60 70 80
0
5
10
y=8.73Ac*10-3
y=3.13Ac*10-2
y=6.25Ac*10-2
K
't1d
ayA
Cn
Acetic acid [mg/m3]
Consider different concentrations of acid
50
100
150
200
250
300
350
400
No acid
Acetic acid (73 ppm)
Mw
(kg
/mo
l)
Half-Life DP
15 days (acetic acid)
21 days (No acid)
Mw (DP)
10,000 100,000 1,000,000
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
logdiff
Mw
Molar mass (g/mol)
0 5 days 15 days 30 days
SEC--MALLS
Half-life DP vs. mechanical properties (Zero-Span tensile)
0 5 10 15 20 25 300
Aging time (days)
0 5 10 15 20 25 300
5
10
15
20
25
Ze
ro s
pa
n t
en
sil
e (
N/m
m)
Aging time (days)
Z-span Tensile
Zero-span tensile tester
Half-life DP 40% loss in Zero-Span tensile strength
Results
Formic acid
(µg/m3)
Rate of degradationCotton
linterHistorical
rag paper
Bleached
chemical
pulp
Book
paper
0 1.00 1.00 1.00 1.00
<200 < 1.05 < 1.02 < 1.01 < 1.01
200-375 1.05 - 1.091.02 -
1.04
1.01 -
1.02
1.01 -
1.02
375-750 1.09 - 1.191.04 - 1.02 - 1.02 -
375-750 1.09 - 1.191.04 -
1.08
1.02 -
1.04
1.02 -
1.04
750-1,500 1.19 - 1.421.08 -
1.16
1.04 -
1.07
1.04 -
1.09
1,500-
3,0001.42 - 1.98
1.16 -
1.35
1.07 -
1.15
1.09 -
1.19
>3,000
(3,000 –
6,000)
1.98 - 3.581.35 -
1.82
1.15 -
1.32
1.19 -
1.40
Dataset available for MEMORI monitoring
Conclusion
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