Glass fiber

The glass fiber is a filament of extremely fine Verre. By extension, the reinforced composite materials of this fiber (generally associated with Polymeric S) are also called glass fiber .

Introduction

The glass fiber is, historically, older than the Fiberoptic 30 years. It was indeed patented in 1930, against the Sixties for fiberoptic. It is however only recently that it revolutionized the glass industry, used for its mechanical and optical qualities.

It is present in several forms, according to the applications envisaged:

chechmate of glass, wire simple or mingled with plastics;
veils not woven for the bituminous covers;
fabrics for the planes, the Mosquito nets;
grids to reinforce cements, the bitumen.

Properties

The glass fiber is interesting at more than one point. Thus it allows reduction of weight by improving the performances, for a competitive price: one can make a mass production of it. It allows for example a lightening of the structures from approximately 30% compared to steel.

Among the other properties, let us quote chemical inertia, the impact resistance, the insulation,…

The principal uses of fiber are, by order of importance (Source: St Gobain-Vetrotex) :

buildings and the infrastructures (29%);
transport (25%);
electricity and electronics (16%);
sports and leisures (14%);
industrial plants (11%).

Manufacture

Manufacture of material of sport, like the poles of Athletics, the Ski S, boards of Surfing.

Raw materials

Several types of glass compositions are used as raw materials, according to the specific use which it will be made of fiber. For fibers of reinforcement, principal glasses used are the suivants :

One also uses boron to lower the melting point and the fluidity of the mixture (what improves the spinning).

Manufactoring process

This process proceeds in 5 principal stages.

Refining with 1500 °C : the composition is heated; it becomes viscous (towards 800 °C), then liquid, and finally is vitrified. With 1500 °C, it is homogeneous, and the last bubbles and impurities disappear.
Spinning by stretching : glass in fusion is transformed into filament while being stretched at high speed; the spinning mill of the filaments is connected in fact with the traditional textile spinning mill to produce a wire. This wire of glass is wound then around a pin.
Oiling : drawing and winding do not have sufficient effect to durably gather the hundreds of filaments in a wire (glass is too smooth to agglomerate). Oiling consists in adding a protective coating to allow the agglomeration of the filaments and to facilitate integration in polymers.
Completion : the wire are then wound or cut according to the finalities.
Drying (oven drying): the wire are finally dried at temperatures of 600 with 700°C.

Uses

The glass fiber finds applications in reinforcement, insulation and optics. The first application is most important by far: the glass fiber is then used to reinforce the polymeric concretes or the in order to manufacture composite materials. Those are then able to replace for steel or the paperboard. The resulting, known composite material under the name of knell-reinforced plastic (GRP) often called “glass fiber” in current language.

In reinforcement

In 9 cases out of 10, the glass fiber is used as generally braces in composite Materials with resin Thermodurcissable S, Polyester, Vinylester or epoxy ( glass fiber epoxy , LIKING). In these materials, as for the Reinforced concrete, the two materials are complementary, compensating for the weaknesses of the other. The fibers bring resistance in traction whereas the matrix enables them to support loads of compression. One uses either the moulding with the contact, or the moulding by compression. In both cases, the use of moulds requires the use of a model (often out of wood).

In the moulding with the contact, the fabric (it is an example) of glass fiber is posed at the bottom of the mould; resin is added, then a roller compresses the whole. The operation is repeated as much once than necessary to obtain the desired thickness.

The moulding by compression uses a heated mould and a against-mould (to accelerate polymerization). A hydraulic press ensures a good distribution of the resin and glass fibers, just like their compression.

In insulation

From the rise to power of the policies of energy-savings, the fiber, by its qualities of insulation, is an obliged test. For this case of figure, manufacture is carried out by gluing of fibers by a synthetic resin. The end product will have the shape of rigid panels or flexible mattresses to protect walls and ceilings, or the shape of shells to insulate the pipes.

In optics

The glass fibers, thanks to their flexibility, their transparency and their excellent line capacity of the light, are united in beam and are used like fiberoptics. The queen use is certainly the endoscopy: a channel makes it possible to light, for example the bronchi, while an other channel returns reflected light on the bronchi to the expert (or with a computer support).

In telecommunication

One can also use it in the applications telecom , by translating the useful signal not into electric impulses, but into luminous impulses. But the long distances require a purity and a mechanical resistance perfect, without what a too great dispersion of the light leads to a loss of the message.

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