EFFECTS OF FREEZE DRYING ON PAPER

INTRODUCTION OBJECTIVES MATERIALS USED EXPERIMENTAL SETUP TREATMENT OF SAMPLES TEST METHODS RESULTS AND DISCUSSION CONCLUSION 2

INTRODUCTION 3

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

7 Groundwood paper / Paper 1

MATERIALS USED 8 Cotton paper / Paper 2

MATERIALS USED 9 Coated paper / Paper 3

EXPERIMENTAL SETUP 10

EXPERIMENTAL SETUP 11

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 contentSCAN P 4:63 Alkali reserveISO Folding enduranceSCAN P 17:77 Tearing resistanceSCAN P 11:73 Zero span tensileCowan/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

RESULTS & DISCUSSION 20 Folding endurance Groundwood paper / Paper 1 Log 10 / GM Reference

RESULTS & DISCUSSION 21 Zero span dry Groundwood paper / Paper 1 Nm/g / GM Reference

RESULTS & DISCUSSION 22 Tearing resistance Groundwood paper / Paper 1 mNm2/g / GM Reference

RESULTS & DISCUSSION 23 Moisture content Groundwood paper / Paper 1 Moisture content % Reference

RESULTS & DISCUSSION 24 Folding endurance Cotton paper / Paper 2 Log 10 / GM Reference

RESULTS & DISCUSSION 25 Tearing resistance Cotton paper / Paper 2 mNm2/g / GM Reference

RESULTS & DISCUSSION 26 Folding endurance Coated paper / Paper 3 Log 10 / GM Reference

RESULTS & DISCUSSION 27 Tearing resistance Coated paper / Paper 3 mNm2/g / GM Reference

RESULTS & DISCUSSION 28

RESULTS & DISCUSSION 29 Retention of folding endurance and tearing resistance after accelerated ageing Retention %

RESULTS & DISCUSSION 30 Retention of zero span tensile strength after accelerated ageing Retention %

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 your attention 36