What types of reinforcing fibers are there?
Commonly available fibers include glass, aramid, carbon, polyester, and polyethylene. Natural 'low tech' fibers include jute, hemp and sisal. More exotic fibers include boron, quartz and ceramic.

What is glass fiber?
Glass fiber is made from the natural materials sand, kaolin, limestone and coalmanite. These are blended together at 1600 degrees Celsius and the molten liquid is drawn through micro sized bushings to produce very fine glass filaments. These are then bundled together in a strand or roving and coated with a 'size' that promotes adhesion and protects the fibers from abrasion. Different types of glass fiber with optimized characteristics include A-glass, E-glass, C-glass, R, S, or T-glass.

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What is Kevlar®?
'Kevlar®' is actually a brand of aramid fiber, which is produced by spinning a solid fiber from a liquid synthetic organic polymer. Composites made using aramid fiber feature high strength, low density and good resistance to impact. Aramid fibers are extremely tough, which makes them ideal for use in automotive applications where high abrasion resistance is required such as under-body panels. However due to this same toughness, aramid composites are hard to repair as broken fibres are very hard to cut, and getting them back below a surface finish is extremely difficult. Aramid has good resistance to chemical and thermal degradation, however the fiber will slowly degrade when exposed to UV rays in sunlight. Several manufacturers offer grades of aramid fiber under brands such as 'Kevlar®' and 'Twaron®' that feature different modulus and surface finishes.

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What is carbon fiber?
Carbon fiber is produced by processing carbon-rich organic pre-cursors, which are already in fiber form. Carbon fiber has the highest specific strength of any commonly available fiber. It features very high strength and low density (weight), very high compressive and tensile strength, and high resistance to fatigue and corrosion. Due to its extremely high stiffness (tensile modulus) carbon fiber has relatively low impact strength. However composite design can overcome this as evidenced by Formula 1 racing cars that can withstand huge impacts. Different types of carbon fiber with optimized characteristics include High Strength (HS), Intermediate Modulus (IM), High Modulus (HM) and Ultra High Modulus (UHM).

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Why use different types of fiber?
One of the key benefits of composites is the ability to engineer different laminates to suit different applications. For example, a carbon fiber composite that uses 200 gsm (gram per square metre) fiber and epoxy resin will have a considerably higher tensile strength, tensile modulus and lower weight than the same component made with 200gsm chopped strand matt glass fiber and the same epoxy resin. The type of reinforcing fibre selected may be based on a wide range of criteria from the highest performance, to the lowest possible cost.

   • Click here to see relative tensile strength of glass, aramid & carbon fiber
   • Click here to see relative tensile modulus of glass, aramid & carbon fiber
   • Click here to see relative specific tensile strength of glass, aramid & carbon fiber

What are the characteristics of different types of fiber?
The following chart summarizes the different characteristics of the three most commonly used fiber reinforcements.

   • Click here to see properties of glass, aramid & carbon fiber
   • Click here to see properties of fibers & other engineering materials

What are the most common reinforcing fibers?
Glass fiber is the most common because it is the cheapest. Chopper guns facilitate fast, economical production and use glass fibers. Chopped Strand Mat is popular because it's inexpensive and easy to use. It conforms easily to complex mold shapes and its porous, low fibre density makes it quick to 'wet out' with resin.

What is the relative cost of different reinforcing fibers?

Aramid and carbon fiber offer significantly higher performance at a higher price. However, due to their superior mechanical properties, lesser quantities can be used to achieve equivalent performance to glass fiber at substantially lower weight..........read more

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