Reinforced absorbent material: a cellulosic composite of TEMPO-oxidized MFC and CTMP fibres

Fredrik Wernersson Brodin,Harald Brelid,Hans Theliander,Kristoffer Lund

doi:10.1007/s10570-012-9706-4

Fredrik Wernersson Brodin, Harald Brelid + Show 2 more

Open Access

https://doi.org/10.1007/s10570-012-9706-4

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Journal: Cellulose	Publication Date: Apr 29, 2012
Citations: 20	License type: CC BY 2.0

Affiliation: Chalmers University of Technology

Abstract

This research aims to develop new materials based on renewable resources that can fulfill the functions necessary in the absorption core of a disposable diaper. Absorbent foam was recently produced from softwood kraft pulp by TEMPO oxidation, disintegration and freeze drying. In this study, the TEMPO-oxidized MFC was mixed with pulp fibres, thus forming a cellulosic composite, in an attempt to improve the mechanical stability of the freeze-dried absorbent material. The fibres were added in different amounts and the freeze-dried materials were evaluated for their absorption and retention properties. The results of this study suggest that the composite material has a better mechanical stability than the absorbent foam without fibres. It was shown that using spruce CTMP fibres in the composite resulted in better absorption and retention capacities than in a composite with softwood kraft pulp fibres. The higher stiffness of the CTMP fibres is a probable explanation for this difference. For the composite material with CTMP fibres, liquid porosimetry showed that pore size distribution was more or less retained when put under load. Furthermore, it was seen that the retention properties reached a maximum around 85 % CTMP fibres and 15 % TEMPO-oxidized MFC. In the centrifuge retention test, the retention of the TEMPO-oxidized MFC in the composite material reached about the same capacity as conventional superabsorbent polymers.

Highlights

Wood derived fibres are widely used in different products where the liquid absorption properties of fibre networks are utilized
This is reflected in the high coarseness of the pulp fibres. This is in contrast to the softwood kraft pulp where virtually all lignin and a significant part of the hemicelluloses are removed from the fibre walls during cooking and subsequent bleaching
It has been shown that addition of fibres has a positive effect on the retention properties of the TEMPOoxidized microfibrillated cellulose (MFC) produced from softwood kraft pulp

Summary

Introduction

Wood derived fibres are widely used in different products where the liquid absorption properties of fibre networks are utilized These properties are at work in disposable diapers where so called fluff pulp fibres in combination with superabsorbent polymers (SAPs) form the absorbent core. The fibres are important for the distribution of liquid and, to some extent, they contribute to the absorption and retention of liquid To supply these functions, a porous network with defined capillary structure is needed. A porous network with defined capillary structure is needed This is accomplished by dry defibration of pulp and subsequent air-laying of the fibres in the absorption core. During the air-laying of the absorbent core, SAP particles are mixed with fluff pulp. The SAP particle swelling drains the fibre network and immobilizes the liquid (Chatterjee 2002)

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