19 Apr 2019 Bhor Chemicals
There are many different types of fibers which can be used to reinforce polymer matrix composites. However the most common are carbon fibers and fiberglass.
Read on to know more about the different types of fiber reinforcement.
1. Carbon (Graphite) Fiber Reinforcement
Carbon fibers are much conductive, but have an excellent combination of high modulus and high tensile strength. Also they have a meagre CTE and thus they offer good resistance to high temperatures.
Carbon fibers are mostly categorised using tensile modulus. There are five categories in carbon fibers which are generally used in composites:
- Low modulus
- Standard modulus
- Intermediate modulus
- High modulus
- Ultra-high modulus
The exact cut-off in these categories may vary depending on the reference but generally, low modulus fibers have a tensile modulus of lesser than 30Msi. Also the ultra-high modulus fibers have tensile modulus greater than 75Msi. For comparison, the steel has a tensile modulus of 29Msi.
As the modulus increases, fibers tend to get more and more brittle, more expensive and much harder to handle.
Furthermore, the tensile strength of the fibers generally increases with the modulus increases from low to intermediate, but then falls off in the high and ultra-high modulus fibers. Thus it can be said that the tensile strength of carbon fibers tends to be the greatest for the intermediate modulus fibers. For such reasons, standard and intermediate modulus fibers are considered to have great performance unless the application is very stiffness oriented.
2. Fiberglass Fiber Reinforcement
Fiberglass is a glass which has been spun into the form of fibers. Fiberglass is comparatively less strong and stiff but has the characteristics which make it desirable in many applications. Fiberglass is non-conductive and is an insulator. It is usually invisible to most types of transmissions. This makes it a great choice while dealing with the electrical or broadcast applications.
There are five major types of fiberglass:
- A-glass (alkali glass)- Good chemical resistance
- C-glass (chemical glass)- Very high chemical resistance
- E-glass (electrical glass)- Excellent insulator and resists attacks from water.
- S-Glass (structural glass)- Optimised for mechanical properties.
- D-glass (dielectric glass)- Has the best electrical properties but lacks in mechanical properties as compared to E and S glass
These types are great combinations of chemical resistance, mechanical properties and insulating properties.
3. Other Fiber Reinforcements
Even though carbon fibers and fiberglass are the most popular fiber reinforcements in thermoplastic composites, there are other alternatives like Aramid fibers like Kevlar, Twaron and boron fibers which are previously used in composites and offer some beneficial properties like amazing toughness and compressive strength. However, they have characteristics which have limited use. These fibers include ceramic fibers, including SiC or aluminum oxide. These fibers may be useful for their compression, insulating, and high-temperature properties.
Automated Dynamics’ staff can also assist with the selection of the best fiber for your application based on program needs, availability, economics, and other factors as well.
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