From sand to fibre
- Batch: silica sand with limestone, alumina and other minerals is melted.
- Fibre drawing: molten glass is drawn through fine bushings into filaments, coated with a sizing, and gathered into strands.
- Forms: continuous strands (rovings), chopped strands, mat and woven fabric.
| Glass type | Typical characteristic | Typical use |
|---|---|---|
| E-glass | General purpose; good electrical insulation | Most pultruded profiles and gratings |
| E-CR (corrosion-resistant) | Better acid resistance than E-glass | Chemical and wastewater uses |
| S-glass | Higher strength and stiffness | High-load and special parts |
| Alkali-resistant (AR) | Resists alkaline attack | Cement and concrete reinforcement |
Why the sizing matters
The thin coating on each filament protects it during handling and chemically links glass to the resin. A poor sizing or a mismatch with the resin reduces strength and water resistance, so fibre and resin are chosen as a pair.
What the polymer does
Glass is stiff and strong but brittle and cannot carry load as loose fibres. The cured resin keeps the fibres aligned, transfers load between them and protects them from water and chemicals. Resin choice is explained in the FRP resin guide, and how fibre layers are arranged in rovings, mat and veils.
Overview of the composite: what FRP is.
The fibre–resin interface and ageing
- A silane coupling agent in the sizing bonds the glass surface to the resin; without it, water creeps along the interface and the composite loses strength.
- Water can wick along fibres at cut edges, so cut surfaces are sealed in wet or chemical service.
- Hydrolysis attacks the resin’s ester groups; vinyl ester and isophthalic resins resist it better than orthophthalic (see resin guide).
- UV degrades the resin at the surface, which exposes fibres (bloom); a surface veil and UV stabiliser slow this.
- High temperature lowers stiffness near the resin’s heat distortion temperature, so keep service temperature well below it.
Send us your requirement
Guangdong Haikuo Composite Materials Co., Ltd. (Huizhou, Guangdong) designs pultrusion moulds in-house and produces custom FRP profiles. Send a drawing, a sample or just the application and the environment, and we will tell you what is feasible.
Email: helena@frphk.cn | Phone: +86 189 5198 8522