Fibre-matrix adhesion -glass fibres

Surface treatments used are discussed elsewhere under Silane adhesion promoters. Fibre-matrix adhesion - glass fibres. 

The performance of all Composite materials is dependent on the adhesion between the different phases. In this article, aspects relevant to carbon-fibre reinforced plastics are discussed. There is a parallel article on Fibre-matrix adhesion - glass fibres. A discussion of the fibre-matrix interface can be found in Fibre composites - introduction. 

As with glass, a range of cloth constructions is available. Further details of the fibres and their surface treatment are discussed under Fibre-matrix adhesion - carbon fibres. 

Scholtens, B. J. R. and Brackman, J. C., Influence of the film former on fibre-matrix adhesion and mechanical properties of glass-fibre reinforced thermoplastics, J. Adhes., 52, 115 (1995). 

The effect of AAPP treatment on the properties of namral fibre reinforced cellulose acetate butyrate (CAB) composites was then further studied [66]. At a fibre loading fraction of 30 wt%, the storage modulus of the short fibre composites improved by as much as 370% (Fig. 6.4). This is due to the enhanced interfacial adhesion between the fibres and the matrix as a result of AAPP treatment (as measured by single fibre pull-out test) [79], In addition to this, the increment in the mechanical glass transition temperature and a reduction in the height of tan 5 showed better fibre-matrix bonding and fibre-in-matrix distribution. It is evident that AAPP treatment is able to improve the fibre-matrix interface, resulting in composites with improved mechanical properties. 

This treatment is known as sizing. As mentioned earlier, the joint between the matrix and the fibre is critical if the reinforcement is to be effective and so the surface film on the glass ensures that the adhesion will be good. 

In practice, there must be some transverse stress. Since Poisson s ratios of matrix and fibres normally differ, in the absence of transverse stress there would be incompatible transverse strains—fibres would no longer fit in their holes in the matrix Often, Poisson s ratio of the fibres is less than that of the matrix, e.g. for glass fibres VfsO.2, and for most plastics v -= 0.3-0.4. This has an advantageous result. Under tension parallel to the fibres, the matrix exerts a pressure on the fibres which assists in maintaining adhesion between them. 

Strength of glass fibre/NR composites can be improved by modification of NR and glass fibre. Modified NR can also give higher strength and better adhesion properties. Modification of glass fibre helps to improve the fibre/matrix adhesion. It is discussed very shortly in this section. 

For systems involving, on the one hand, poorly polar matrices, such as polyethylene, polyvinylchloride and polyurethane and, on the other hand, untreated and surface treated glass or carbon fibres, it has been shown in our laboratory [12,13] that a linear relationship can be established to a first approximation between t and the reversible work of adhesion W defined by equation (5). However for more polar matrices, like epoxy resin for example, such a relationship is no longer valid, since strong specific interactions are now established at the fibre-matrix interface. 

The creep and fatigue behaviour for natural fibre-reinforced plastics is less weU understood than for glass fibre-reinforced plastics because of the lack of systematic and detailed information. Limited information is currently available oti the effects on the fatigue behaviour of natural fibre-reinforced plastics of different composite parameters such as fibre type, the quality of fibre-matrix adhesion and fibre properties and their content. 

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