The influence of periodate oxidation on the moisture sorptivity and dimensional stability of paper |
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Authors: | Per A Larsson Magnus Gimåker Lars Wågberg |
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Institution: | (1) Fibre and Polymer Technology, KTH, The Royal Institute of Technology, 100 44 Stockholm, Sweden;(2) BIM Kemi Sweden AB, Box 3102, 443 03 Stenkullen, Sweden |
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Abstract: | The hygroexpansion of paper was significantly reduced, up to 28% lower amplitude of change when the paper was subjected to
a change in relative humidity from 20 to 85% RH, by oxidation of the fibre wall. Never-dried bleached kraft fibres were oxidised
with sodium periodate, which specifically oxidises the C2–C3 bond of 1,4-glucans so that the cellulose is partly converted
into dialdehyde cellulose. Since both the dry and wet strength of laboratory sheets were significantly improved, the dry tensile
strength increased from 24 kNm/kg up to 66 kNm/kg and the relative wet tensile strength increased from 1.5% up to 40%, it
is suggested that the aldehydes form hemiacetal linkages within the fibre wall during the consolidation and drying of the
sheets. The mechanical, hygroexpansive and moisture sorptive properties of the sheets made from the oxidised fibres were studied.
The results showed that the main reason for the reduced hygroexpansion was a decrease in moisture sorptivity, i.e. when the
sheets made of fibres with different degrees of cross-linking were subjected to the same change in relative humidity, the
more cross-linked fibres showed a smaller change in moisture content. It was also shown that the hygroexpansion coefficient,
i.e. the moisture-normalised dimensional change, was not significantly changed by the periodate oxidation, i.e. indicating
that there are no improvement in dimensional stability if the paper is subjected to a specific amount of water. |
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Keywords: | Cross-linking Dimensional stability Hygroexpansion Moisture adsorption Periodate oxidation |
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