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