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EFFECTS OF FREEZE DRYINGON PAPER
INTRODUCTION
OBJECTIVES
MATERIALS USED
EXPERIMENTAL SETUP
TREATMENT OF SAMPLES
TEST METHODS
RESULTS AND DISCUSSION
CONCLUSION
2
INTRODUCTION
3
INTRODUCTION
to investigate how freeze drying effects paper characteristics critical to preservation of archive and library materials
to determine how freeze drying might effect the mechanical strength and ageing stability of paper
4
INTRODUCTION
5
MATERIALS USED
6
MATERIALS USED
7
Groundwood paper / Paper 1
Fibre composition 75 % groundwood and 25 % softwood cellulose
Filler 22 % kaolin clay
Sizing Alum rosin and casein
pH extract 5,9
Ash content, % 20
Grammage, g/m2 80
Producer Unknown. Supplied by STFI
MATERIALS USED
8
Cotton paper / Paper 2
Fibre composition 100 % cotton
Fillers 2-4 % calcium carbonate and 0,5-1 % titandioxide
Sizing Alkyl ketene dimer and polyvinyl alcohol
pH extract 9,9
Ash content, % 2,45
Grammage, g/m2 80
Producer Tumba AB. Supplied by STFI
MATERIALS USED
9
Coated paper / Paper 3
Fibre composition 100 % chemical cellulose
Filler (base) Calcium carbonate
Sizing (base) Alkyl ketene dimer
Sizing (coating) Styrene butadiene latex and carboxy methylcellulose
Pigment (coating) Kaolin clay
pH extract -
Ash content, % 32
Grammage, g/m2 80
Producer Grycksbo. Supplied by Grycksbo
EXPERIMENTAL SETUP
10
Freeze dried cold Freeze dried warm Air driedUnaged Unaged Unaged
EXPERIMENTAL SETUP
11
ReferenceUntreated
Freeze dried cold Freeze dried warm Air driedUnaged Unaged Unaged
Accelerated ageing Accelerated ageing Accelerated ageing Accelerated ageingFreeze dried cold & aged Freeze dried warm & aged Air dried & aged Untreated but aged
TREATMENT OF SAMPLES
12
Soaking in demineralized water
TREATMENT OF SAMPLES
13
Freeze drying by cold chamber wall
TREATMENT OF SAMPLES
14
Freeze drying by warm chamber wall
TREATMENT OF SAMPLES
15
TREATMENT OF SAMPLES
16
Accelerated ageing
TREATMENT OF SAMPLES
17
Accelerated ageing
12 days (288 hours)
90 ºC
50 % RH
TEST METHODS
Moisture content SCAN P 4:63
Alkali reserve ISO 10716
Folding endurance SCAN P 17:77
Tearing resistance SCAN P 11:73
Zero span tensile Cowan/TAPPI 231 (dry and wet determination)
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RESULTS & DISCUSSION
freeze drying particulary influences moisture content, folding endurance and tearing resistance
freeze drying and accelerated ageing influence moisture content, folding endurance and tearing resistance in the samples, but differently from one paperquality to another
the effect on alkali reserve and zero span tensile strength is relatively small
19
2,18
2,62
2,3
2,59
1,91 1,97
0,69
0,96
0
1
2
3
4
5
Untreated Freeze dried cold Freeze dried warm Air dried
Log
10
/ G
M
Unaged
Aged
RESULTS & DISCUSSION
20
Folding enduranceGroundwood paper / Paper 1
Log
10
/ G
M
Ref
ere
nce
RESULTS & DISCUSSION
21
Zero span dryGroundwood paper / Paper 1
73,2769,1673,07 70,664,78
58.667,55
71,95
0
25
50
75
100
125
150
175
200
Untreated Freeze dried cold Freeze dried warm Air dried
Nm
/g /
GM
Unaged
Aged
Nm
/g /
GM
Ref
ere
nce
RESULTS & DISCUSSION
22
Tearing resistanceGroundwood paper / Paper 1
3,863,693,31
3,7
2,42,38
3,172,54
0
2
4
6
8
10
12
14
Untreated Freeze dried cold Freeze dried warm Air dried
mN
m2
/g /
GM
Unaged
Aged
mN
m2/
g /
GM
Ref
ere
nce
RESULTS & DISCUSSION
23
Moisture contentGroundwood paper / Paper 1
8,227,55
8,46
7,66
6,757,5
8,38
4,84
0
2
4
6
8
10
12
14
Untreated Freeze dried cold Freeze dried warm Air dried
Mo
istu
re c
on
ten
t %
Unaged
Aged
Moi
stu
re c
onte
nt
%
Ref
ere
nce
RESULTS & DISCUSSION
24
Folding enduranceCotton paper / Paper 2
2,712,542,61 2,59 2,642,56
2,432,57
0
1
2
3
4
5
Untreated Freeze dried cold Freeze dried warm Air dried
Log
10
/ G
M
Unaged
Aged
Log
10
/ G
M
Ref
ere
nce
RESULTS & DISCUSSION
25
Tearing resistanceCotton paper / Paper 2
8,328,66
7,76
9,22
7,547,87
8,46
7,17
0
2
4
6
8
10
12
14
Untreated Freeze dried cold Freeze dried warm Air dried
mN
m2
/g /
GM
Unaged
Aged
mN
m2/
g /
GM
Ref
ere
nce
RESULTS & DISCUSSION
26
Folding enduranceCoated paper / Paper 3
2,182,02
2,36
1,852,031,93
1,62
2,22
0
1
2
3
4
5
Untreated Freeze dried cold Freeze dried warm Air dried
Log
10
/ G
M
Unaged
Aged
Log
10
/ G
M
Ref
ere
nce
5,525,48
4,6
5,795,225,23
5,63
4,66
0
2
4
6
8
10
12
14
Untreated Freeze dried cold Freeze dried warm Air dried
mN
m2/g
/ G
M
Unaged
Aged
RESULTS & DISCUSSION
27
Tearing resistanceCoated paper / Paper 3
mN
m2/
g /
GM
Ref
ere
nce
RESULTS & DISCUSSION
28
RESULTS & DISCUSSION
29
Retention of folding endurance andtearing resistance after accelerated ageing
0
80
160
FC P1 FW P1 AD P1 FC P2 FW P2 AD P2 FC P3 FW P3 AD P3
Re
ten
tio
n %
/ G
M
Folding endurance
Tear index
FC: Freeze dried cold
FW: Freeze dried warm
AD: Air dried
Ret
ent
ion
%
RESULTS & DISCUSSION
30
Retention of zero span tensilestrength after accelerated ageing
0
80
160
FC P1 FW P1 AD P1 FC P2 FW P2 AD P2 FC P3 FW P3 AD P3
Re
ten
tio
n %
/ G
M
Zero span tensile index, dry
Zero span tensile index, wet
FC: Freeze dried cold
FW: Freeze dried warm
AD: Air dried
Ret
ent
ion
%
CONCLUSION
31
CONCLUSION
32
freeze drying particularly influences moisture content, folding endurance and tearing resistance
freeze drying and accelerated ageing effect moisture content, folding endurance and tearing resistance differently in various paperqualities
freeze drying of groundwood paper and alum-rosin sized paper with a high amount of fillers reduces the mechanical strength
CONCLUSION
33
freeze drying of cotton paper with a high content of calcium carbonate has a relatively limited effect on mechanical strength and ageing stability
freeze drying of coated paper particularly reduces folding endurance
CONCLUSION
34
ACKNOWLEDGEMENT
35
Jonas Palm, The Royal Library
Grethe Jørgensen, The School of Conservation
Jørn Bredal-Jørgensen, The School of Conservation
Anette Linde, Swedish Pulp and Paper Research Inst.
Poul Jensen, The National Museum
Julie Fryd Johansen, The Royal Library
Stora Papyrus, Grycksbo
Thank you for yourattention
36
:-)
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