Glass Fibres
In order to handle the fine filamentary fibres that are necessary
for structural composites the fibres are usually in the form of
bundles. The bundles are drawn continuously from platinum-rhodium
bushings, each producing several hundred filaments. The fibres are
pulled away at speeds approaching 1000 to 2000 m/min. as molten glass
and coated with size which lubricates the surface to prevent abrasion
before the filaments (100-1200) are brought together into a tow and
wound onto a mandrel.
The Glass fibres are available in several forms. The main
varieties are:- Chopped Strands - Short lengths of fibre in bundles of ~100fibres. Length 3 to 40 mm used in automated pressing and mouldingwith both thermosetting and thermoplastic matrices as well ascement.
- Chopped Strand Mat - chopped strands in the size 30 to 40mmare distributed over the area of a conveyor belt in randomorientations an a small amount of an organic binder (usually polyvinyl acetate) added to form a loosely bound open mat which isreadily impregnated by resin. Binder must be compatible with theresin - normally used with polyester or epoxy resins.
- Rovings - A number of strands are grouped together and woundwithout twisting onto a cylindrical package to give a longcontinuous rope or large tow that may be used for filament windingor for chopping and spraying.
- Yarn - twisted strands used in weaving cloth.
The glass comprises one of two main types: Traditional glass fibre
used for reinforcing rubbers and plastics and Alkali resistant for
reinforcing cement.Types of Glass
- E Glass is the all purpose fibre. Resistant to leaching inwater.
- C-Glass is acid resistant - not generally used as areinforcement.
- A Glass is a typical window glass for comparison purposes andis not used in fibre manufacture
- S Glass has highest strength and stiffness
- AR glass is alkali resistant and used for strengtheningcements.
| Fibre | SiO2 | Al2O3 | Fe2O3 | B2O3 | ZrO2 | MgO | CaO | Na2O | K2O | TiO2
|
| A-Glass | 73 | 1 | 0.1 | - | - | 4 | 8 | 13 | 0.5 | -
|
| E-Glass | 52-56 | 12-16 | 0-0.5 | 8-13 | - | 0-6 | 16-25 | - | - | -
|
| AR Glass | 60-70 | 0-5 | - | - | 15-20 | - | 0-10 | 10-15 | - | 0-5
|
| C Glass | 59-64 | 3-5 | 0.1-0.3 | 6-7 | - | 2-4 | 13-14 | 8-11 | 0.4-0.7 | -
|
| S Glass | 50-85 | 10-35 | - | - | - | 4-25 | - | 0 | | - |
| Fibre | E(GPa) | Strength (MPa) | u | Density (g/cm3) | Tm or Tg (°C)
|
| A-Glass | | | | |
|
| E-Glass | 72 | 1700 - 2100 | 0.2 | 2.50 | 1500
|
| AR Glass | 70 | 1500 - 1900 | | |
|
| C Glass | | | | |
|
| S Glass | 80 | 2000 - 2500 | 0.22 | 2.54 | 1400 |
Return to Class Index. Back to Previous
class. Forward to Next Class.
