Glass fibre matrix

Extraction discs (0.5 mm thick, 25 to 90 mm diameter) constitute a variation of column-based SPE. These discs allow rapid extraction of large volumes of sample, which is not possible using a small column. The discs are made of bonded-phase silica particles, a few micrometres in diameter, trapped in a porous Teflon or glass fibre matrix. The discs are operated in a similar way to a paper filter on a vacuum flask. After extraction, the analyte is recovered by percolating a solvent through the filter. The major application of this technique is the isolation of trace amounts of compound dispersed in an aqueous medium. 

A 2.5 X 2.5 cm glass fibre matrix is fitted into a plastic case (tab) (Fig. 53). The prepared antibody can now be applied to the glass fibre matrix. The specific antibody for each test is firmly crosslinked into this matrix by a carrier antibody, the bonding by the carrier antibody being effected by a chemical bond. The specific antibody is produced in the rabbit the antibody for fixation is an anti-rabbit antibody from the goat. The glass fibre matrix is used to prevent unspecific reactions. On these carriers prepared in this manner the tests can be performed according to the competitive, sequential or sandwich technique. 

A composite material for a car-repair kit consists of a random mixture of short glass fibres in a polyester matrix. Estimate the maximum toughness of the composite. You may assume that the volume fraction of glass is 30% the fibre diameter is 15 pm the fracture strength of the fibres is 1400 MPa and the shear strength of the matrix is 30 MPa. 

The poor stability on exposure to air and water, particularly at elevated temperatures, which results in a reduction in conductivity, also poses problems. In the case of polypyrrole it has been found that conductivity can, however, be maintained either by the drastic measure of storing under the protective layer of the inert gas argon or embedding polypyrrole film in a matrix of an epoxide resin-glass-fibre composite. 

Polyesters. The main application of this material is as a matrix for glass fibre reinforcement. This can take many forms and is probably most commonly known as a DIY type material used for the manufacture of small boats, chemical containers, tanks and repair kits for cars, etc. 

Example 3.1 The density of a composite made from unidirectional glass fibres in an epoxy matrix is 1950 kg/m. If the densities of the glass and epoxy... 

A hybrid composite material is made up of 20% HS carbon fibres by weight and 30% E-glass fibres by weight in an epoxy matrix. If the density of the epoxy is 1300 kg/m and the data in Fig. 3.2 may be used for the fibres, calculate the density of the composite. 

A reinforced plastic sheet is to be made from a matrix with a tensile strength of 60 MN/m and continuous glass fibres with a modulus of 76 GN/m. If the resin ratio by volume is 70% and the modular ratio of the composite is 25, estimate the tensile strength and modulus of the composite. 

If the matrix in 3.7 was reinforced with the same volume fraction of glass but in the form of randomly oriented glass fibres rather than continuous filaments, what would be the tensile strength of the composite. The fibres are 15 mm long, have an aspect ratio of 1000 and produce a reinforcement efficiency of 0.25. The fibre strength is 2 GN/m and the shear strength of the interface is 4 MN/m". 

A polyester matrix is reinforced with continuous glass fibres. A 15 mm wide beam made from this material is to be simply supported over a 300 mm length and have a point load at midspan. For a fixed beam weight of 90 g/m investigate how the stiffness of the beam changes with the volume fraction of glass and state the optimum volume fraction, (p/ = 2560 kg/m. p , = 1210 kg/m Ef = 76 GN/m = 3 GN/m ). 

The highest mechanical strengths are usually obtained when the fibre is used in fine fabric form but for many purposes the fibres may be used in mat form, particularly glass fibre. The chemical properties of the laminates are largely determined by the nature of the polymer but capillary attraction along the fibre-resin interface can occur when some of these interfaces are exposed at a laminate surface. In such circumstances the resistance of both reinforcement and matrix must be considered when assessing the suitability of a laminate for use in chemical plant. Glass fibres are most commonly used for chemical plant, in conjunction with phenolic resins, and the latter with furane, epoxide and, sometimes, polyester resins. 

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 properties of polymers reinforced with chopped glass fibres dispersed in the polymer matrix depend on ... 

Depending on the rigidity and the ductility of the matrix, when a stress is applied to a short glass fibre reinforced composite the following steps can be observed ... 

Note in both cases that the specific tensile strength of glass fibres is very much higher than the specific tensile strength of the matrix. The ratio is 4.8 for dry samples and 3.5 at 50% RH. 

In all cases, carbon fibres lead to the highest mechanical performances compared to glass and aramid fibres. Nevertheless, their impact behaviour and price restrict their consumption. Glass fibres yield the cheapest composites but performances are more limited. Table 6.10 compares the properties of the main fibre types and shows some examples of properties for a nylon matrix reinforced with short fibres of the three types. 

Fibre-reinforced glass/glass-ceramic matrix composites... 

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