Fabrics of woven glass fibers are useful thermal insulators because of their high ratio of surface area to weight. However, the increased surface area makes them much more susceptible to chemical attack. By trapping air within them, blocks of glass fiber make good thermal insulation, with a thermal conductivity of the order of 0.05 W/(m·K).
| Fiber type |
Tensile strength (MPa)[10] |
Compressive strength (MPa) |
Density (g/cm3) |
Thermal expansion (μm/m·°C) |
Softening T (°C) |
Price ($/kg) |
|---|---|---|---|---|---|---|
| E-glass | 3445 | 1080 | 2.58 | 5 | 846 | ~2 |
| S-2 glass | 4890 | 1600 | 2.46 | 2.9 | 1056 | ~20 |
The strength of glass is usually tested and reported for "virgin" or pristine fibers—those that have just been manufactured. The freshest, thinnest fibers are the strongest because the thinner fibers are more ductile. The more the surface is scratched, the less the resulting tenacity.Because glass has an amorphous structure, its properties are the same along the fiber and across the fiber. Humidity is an important factor in the tensile strength. Moisture is easily adsorbed and can worsen microscopic cracks and surface defects, and lessen tenacity.
In contrast to carbon fiber, glass can undergo more elongation before it breaks.Thinner filaments can bend further before they break.The viscosity of the molten glass is very important for manufacturing success. During drawing, the process where the hot glass is pulled to reduce the diameter of the fiber, the viscosity must be relatively low. If it is too high, the fiber will break during drawing. However, if it is too low, the glass will form droplets instead of being drawn out into a fiber.
Uses
Uses for regular glass fiber include mats and fabrics for thermal insulation, electrical insulation, sound insulation, high-strength fabrics or heat- and corrosion-resistant fabrics. It is also used to reinforce various materials, such as tent poles, pole vault poles, arrows, bows and crossbows, translucent roofing panels, automobile bodies, hockey sticks, surfboards, boat hulls, and paper honeycomb. It has been used for medical purposes in casts. Glass fiber is extensively used for making FRP tanks and vessels.
Open-weave glass fiber grids are used to reinforce asphalt pavement.Non-woven glass fiber/polymer blend mats are used saturated with asphalt emulsion and overlaid with asphalt, producing a waterproof, crack-resistant membrane. Use of glass-fiber reinforced polymer rebarinstead of steel rebar shows promise in areas where avoidance of steel corrosion is desired.
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