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AN EXPERIMENTAL STUDY OF THE UNRESTRAINED SHRINKAGE OF ISOTROPICPAPER SHEETS

Mayeli, Nader

[Thesis]. Manchester, UK: The University of Manchester; 2015.

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Abstract

The influence of several hardwoods and softwoods pulp fibre on the free shrinkage ofisotropic paper sheets was investigated. The Effect of properties such as density,grammage, Fractional Contact Area (FCA), Water Retention Value (WRV), fines contentand fibre morphology were also investigated on the free shrinkage of isotropic papersheets. Further, the influence of Lyocell fibre and glycerol on the free shrinkage ofisotropic paper sheets is reported. Experimental results showed that in general the freeshrinkage of hardwood pulps is a few percent higher than that of softwood pulps at thesame density. It was found that although free shrinkage increases with fines content, ahigh fines content does not imply high shrinkage, and some pulp samples with higheramount of fines, exhibited lower free shrinkage. For all pulps at low densities there is littleinfluence of grammage on free shrinkage, though as density increases a significantdependence is observed. The results showed that the free shrinkage of isotropic papersheets formed from hardwood pulps is more sensitive to grammage compared to that ofsoftwood pulps. Interestingly, it was shown that some pulp samples with the same intrinsicdensity, WRV and FCA exhibited different free shrinkage over the range of grammages.In addition, some pulp samples with stiffer fibres but higher amount of fines exhibitedhigher free shrinkage. Experimental results showed that longitudinal shrinkage of a fibre isan important parameter and pulp samples with higher microfibril angle (MFA) exhibitedhigher longitudinal shrinkage. Finally, the free shrinkage of isotropic paper sheets wasreduced by applying Lyocell fibre and glycerol. Interestingly, by adding a small amount ofLyocell fibre, 2%, an increase in tensile index, tensile energy absorption (TEA) andmodulus is observed, while the free shrinkage reduced up to 2%. In addition, addingglycerol to the pulp samples not only reduced the free shrinkage of isotropic paper sheetsup to 1.5%, but also mechanical properties, such as tensile index and stretch slightlyimproved.

Layman's Abstract

The influence of several hardwoods and softwoods pulp fibre on the free shrinkage ofisotropic paper sheets was investigated. The Effect of properties such as density,grammage, Fractional Contact Area (FCA), Water Retention Value (WRV), fines contentand fibre morphology were also investigated on the free shrinkage of isotropic papersheets. Further, the influence of Lyocell fibre and glycerol on the free shrinkage ofisotropic paper sheets is reported. Experimental results showed that in general the freeshrinkage of hardwood pulps is a few percent higher than that of softwood pulps at thesame density. It was found that although free shrinkage increases with fines content, ahigh fines content does not imply high shrinkage, and some pulp samples with higheramount of fines, exhibited lower free shrinkage. For all pulps at low densities there is littleinfluence of grammage on free shrinkage, though as density increases a significantdependence is observed. The results showed that the free shrinkage of isotropic papersheets formed from hardwood pulps is more sensitive to grammage compared to that ofsoftwood pulps. Interestingly, it was shown that some pulp samples with the same intrinsicdensity, WRV and FCA exhibited different free shrinkage over the range of grammages.In addition, some pulp samples with stiffer fibres but higher amount of fines exhibitedhigher free shrinkage. Experimental results showed that longitudinal shrinkage of a fibre isan important parameter and pulp samples with higher microfibril angle (MFA) exhibitedhigher longitudinal shrinkage. Finally, the free shrinkage of isotropic paper sheets wasreduced by applying Lyocell fibre and glycerol. Interestingly, by adding a small amount ofLyocell fibre, 2%, an increase in tensile index, tensile energy absorption (TEA) andmodulus is observed, while the free shrinkage reduced up to 2%. In addition, addingglycerol to the pulp samples not only reduced the free shrinkage of isotropic paper sheetsup to 1.5%, but also mechanical properties, such as tensile index and stretch slightlyimproved.

Bibliographic metadata

Type of resource:
Content type:
Administered thesis
Form of thesis:
Traditional
Type of submission:
Doctoral level ETD - final
Thesis title:
AN EXPERIMENTAL STUDY OF THE UNRESTRAINED SHRINKAGE OF ISOTROPICPAPER SHEETS
Degree type:
Doctor of Philosophy
Degree programme:
PhD Materials
Publication date:
2015-12-18T13:40:13
Institution:
The University of Manchester
Location:
Manchester, UK
Total pages:
220
Abstract:
The influence of several hardwoods and softwoods pulp fibre on the free shrinkage ofisotropic paper sheets was investigated. The Effect of properties such as density,grammage, Fractional Contact Area (FCA), Water Retention Value (WRV), fines contentand fibre morphology were also investigated on the free shrinkage of isotropic papersheets. Further, the influence of Lyocell fibre and glycerol on the free shrinkage ofisotropic paper sheets is reported. Experimental results showed that in general the freeshrinkage of hardwood pulps is a few percent higher than that of softwood pulps at thesame density. It was found that although free shrinkage increases with fines content, ahigh fines content does not imply high shrinkage, and some pulp samples with higheramount of fines, exhibited lower free shrinkage. For all pulps at low densities there is littleinfluence of grammage on free shrinkage, though as density increases a significantdependence is observed. The results showed that the free shrinkage of isotropic papersheets formed from hardwood pulps is more sensitive to grammage compared to that ofsoftwood pulps. Interestingly, it was shown that some pulp samples with the same intrinsicdensity, WRV and FCA exhibited different free shrinkage over the range of grammages.In addition, some pulp samples with stiffer fibres but higher amount of fines exhibitedhigher free shrinkage. Experimental results showed that longitudinal shrinkage of a fibre isan important parameter and pulp samples with higher microfibril angle (MFA) exhibitedhigher longitudinal shrinkage. Finally, the free shrinkage of isotropic paper sheets wasreduced by applying Lyocell fibre and glycerol. Interestingly, by adding a small amount ofLyocell fibre, 2%, an increase in tensile index, tensile energy absorption (TEA) andmodulus is observed, while the free shrinkage reduced up to 2%. In addition, addingglycerol to the pulp samples not only reduced the free shrinkage of isotropic paper sheetsup to 1.5%, but also mechanical properties, such as tensile index and stretch slightlyimproved.
Layman's abstract:
The influence of several hardwoods and softwoods pulp fibre on the free shrinkage ofisotropic paper sheets was investigated. The Effect of properties such as density,grammage, Fractional Contact Area (FCA), Water Retention Value (WRV), fines contentand fibre morphology were also investigated on the free shrinkage of isotropic papersheets. Further, the influence of Lyocell fibre and glycerol on the free shrinkage ofisotropic paper sheets is reported. Experimental results showed that in general the freeshrinkage of hardwood pulps is a few percent higher than that of softwood pulps at thesame density. It was found that although free shrinkage increases with fines content, ahigh fines content does not imply high shrinkage, and some pulp samples with higheramount of fines, exhibited lower free shrinkage. For all pulps at low densities there is littleinfluence of grammage on free shrinkage, though as density increases a significantdependence is observed. The results showed that the free shrinkage of isotropic papersheets formed from hardwood pulps is more sensitive to grammage compared to that ofsoftwood pulps. Interestingly, it was shown that some pulp samples with the same intrinsicdensity, WRV and FCA exhibited different free shrinkage over the range of grammages.In addition, some pulp samples with stiffer fibres but higher amount of fines exhibitedhigher free shrinkage. Experimental results showed that longitudinal shrinkage of a fibre isan important parameter and pulp samples with higher microfibril angle (MFA) exhibitedhigher longitudinal shrinkage. Finally, the free shrinkage of isotropic paper sheets wasreduced by applying Lyocell fibre and glycerol. Interestingly, by adding a small amount ofLyocell fibre, 2%, an increase in tensile index, tensile energy absorption (TEA) andmodulus is observed, while the free shrinkage reduced up to 2%. In addition, addingglycerol to the pulp samples not only reduced the free shrinkage of isotropic paper sheetsup to 1.5%, but also mechanical properties, such as tensile index and stretch slightlyimproved.
Keyword(s):
Thesis main supervisor(s):
Thesis co-supervisor(s):
Degree grantor:
Language:
en

Institutional metadata

University researcher(s):
Academic department(s):

Record metadata

Manchester eScholar ID:
uk-ac-man-scw:292838
Created by:
Mayeli, Nader
Created:
18th December, 2015, 13:40:14
Last modified by:
Mayeli, Nader
Last modified:
3rd January, 2018, 13:52:43

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