EFFECTS OF FREEZE DRYING ON PAPER. INTRODUCTION OBJECTIVES MATERIALS USED EXPERIMENTAL SETUP TREATMENT OF SAMPLES TEST METHODS RESULTS AND DISCUSSION

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


12

Soaking in demineralized water


13

Freeze drying by cold chamber wall


14

Freeze drying by warm chamber wall


15


16

Accelerated ageing


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)

18

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


20

Folding enduranceGroundwood paper / Paper 1

Log

10

/ G

M

Ref

ere

nce


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


Nm

/g /

GM

Unaged

Aged

Nm

/g /

GM

Ref

ere

nce


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


mN

m2

/g /

GM

Unaged

Aged

mN

m2/

g /

GM

Ref

ere

nce


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


Mo

istu

re c

on

ten

t %

Unaged

Aged

Moi

stu

re c

onte

nt

%

Ref

ere

nce


24

Folding enduranceCotton paper / Paper 2

2,712,542,61 2,59 2,642,56

2,432,57

0

1

2

3

4

5


Log

10

/ G

M

Unaged

Aged

Log

10

/ G

M

Ref

ere

nce


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


mN

m2

/g /

GM

Unaged

Aged

mN

m2/

g /

GM

Ref

ere

nce


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


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


mN

m2/g

/ G

M

Unaged

Aged


27

Tearing resistanceCoated paper / Paper 3

mN

m2/

g /

GM

Ref

ere

nce


28


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

%


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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EFFECTS OF FREEZE DRYING ON PAPER. INTRODUCTION OBJECTIVES MATERIALS USED EXPERIMENTAL SETUP TREATMENT OF SAMPLES TEST METHODS RESULTS AND DISCUSSION