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Comparison of water absorption in natural cellulosic fibres from wood and one-year crops in polypropylene composites and its influence on their mechanical properties
KTH, Superseded Departments, Fibre and Polymer Technology.
KTH, Superseded Departments, Fibre and Polymer Technology.ORCID iD: 0000-0003-3572-7798
KTH, Superseded Departments, Fibre and Polymer Technology.ORCID iD: 0000-0002-5394-7850
2004 (English)In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, Vol. 35, no 11, 1267-1276 p.Article in journal (Refereed) Published
Abstract [en]

Environmentally beneficial composites can be made by replacing glass fibres with various types of cellulose fibres. Fibres from pine or eucalyptus wood and also one-year crops such as coir, sisal, etc. are all good candidates. The poor resistance towards water absorption is one of the drawbacks of natural fibres/polypropylene composites. New natural fibres/polypropylene composites were made and the water absorption in them was studied by immersion of the composites in water at three different temperatures, 23, 50 and 70 degreesC. The process of absorption of water was found to follow the kinetics and mechanisms described by Fick's theory. In addition, the diffusivity coefficient was dependent on the temperature as estimated by means of Arrhenius law. A decrease in tensile properties of the composites was demonstrated, showing a great loss in mechanical properties of the water-saturated samples compared to the dry samples. The morphology change was monitored by scanning electron microscopy studies of the samples before and after exposure to water and the devastating effect of water on the fibre structure was shown.

Place, publisher, year, edition, pages
2004. Vol. 35, no 11, 1267-1276 p.
Keyword [en]
polymer-matrix composites (PMCs), mechanical properties, water absorption, behavior, morphology, moisture
National Category
Chemical Sciences
URN: urn:nbn:se:kth:diva-23744DOI: 10.1016/j.compositesa.2004.04.004ISI: 000224021600004ScopusID: 2-s2.0-4444369381OAI: diva2:342443
QC 20100525 QC 20111101Available from: 2010-08-10 Created: 2010-08-10 Last updated: 2011-11-01Bibliographically approved
In thesis
1. Strategies for improving mechanical properties of polypropylene/cellulose composites
Open this publication in new window or tab >>Strategies for improving mechanical properties of polypropylene/cellulose composites
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The interest for polypropylene/cellulose composites has experienced a great increase in different applications such as car interiors and construction materials. Cellulose fibres are inexpensive, renewable, biodegradable, they present lower density and their mechanical properties can be compared to those of inorganic fillers. However, several factors must be considered when designing polypropylene/cellulose composites: the poor compatibility between the hydrophilic fibres and the hydrophobic thermoplastic matrix leads to a weak interface, which has to be improved by coupling agents; the hydrophilic nature of the fibres makes them very sensitive towards water absorption, which also leads to a loss of properties and swelling with subsequent dimensional instability; the reduced thermal stability of cellulose fibres leads to degradation of the fibres at thermoplastic processing temperatures producing odours in the final material; and finally the properties of composites are greatly influenced by the structure, size and quality of the fibres.

Pulp fibres modified by different methods in order to enhance the compatibility fibre-matrix, were tested. Modified fibres led to improved mechanical properties and thermal behaviour when used in composites with recycled polypropylene.

Four different types of natural fibres were used as reinforcement in two different polypropylene types: virgin and recycled polypropylene. The mechanical properties of the composites were mostly dependent on the fibre loading and slightly dependent on the type of fibre. Moreover, water absorption kinetics was studied by the Fickian diffusion theory. After absorption, a remarkable loss of properties was observed.

Hydrolysed cellulose fibres showed a greater enhancing effect on polypropylene than non-hydrolysed cellulose fibres. This is attributed to the greater mechanical properties of reduced cellulose structures.

The effect of using cellulose fibres in PP/clay nanocomposites was also studied. The interaction between the clay particles and the cellulose fibres and the combined effect of both reinforcements were believed to be the main reasons for the enhancing properties.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. 58 p.
Trita-FPT-Report, ISSN 1652-2443 ; 2005:12
Chemistry, polymer technology, chemical engineering, materials science, polymer, Kemi
National Category
Chemical Sciences
urn:nbn:se:kth:diva-179 (URN)91-7283-998-8 (ISBN)
Public defence
2005-04-29, Sal K1, Teknikringen 56, Stockholm, 10:00
QC 20101011Available from: 2005-04-27 Created: 2005-04-27 Last updated: 2010-10-11Bibliographically approved

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Espert, AnaVilaplana, FranciscoKarlsson, Sigbritt
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