Fiber Composites: Properties and Matrix Comparison

Posted on Jan 26, 2025 in Materials Engineering

Glass Fiber

• Easily converted into high resistance fibers.
• Easily available and economically achievable.
• Compatible with most manufacturing processes.
• Relatively strong fibers, but stiffness not very high.
• Chemically inert when combined with many plastics.
• Good adhesion with most resins.
• Small thermal expansion.

The basic constituent of glass fiber is silicon, combined with other elements. To avoid surface defects due to abrasion during the wire drawing process, a sizing coating is used.

Carbon Fiber

• Very high elastic modulus.
• High strength (HS) or high modulus (HM) fibers.
• High compression and fatigue strength.
• High temperature resistant in non-oxidant atmosphere.
• Chemically resistant at room temperature.
• Thermal expansion is zero, even negative in the fiber’s longitudinal direction.
• Good electrical and thermal conductivity.
• Good resistance to humidity.

Disadvantages

• Expensive.
• Low toughness and bad abrasion-resistant.
• Does not support oxidant acids at high temperatures, nor metals that can form carbides.

Organic Fibers

Difficult manufacturing

Aramid or Aromatic Polyamide

• High specific tensile strength.
• Zero or negative thermal expansion in longitudinal direction.
• Very good absorption of vibrations.
• Very good impact resistant, as well as penetration, abrasion and fatigue resistant.
• Good chemical resistant except to very hard acid or bases.

Drawbacks

Weak at compression (so in bending), hygroscopic (absorb water) and adhesion with resins not good. Must be cut with specific cutters or scissors.

Fibers Comparison

Glass Fiber: Cheap, especially mat. Lightweight, toughness, stiffness and strength. Improvements in stiffness and strength when cloth glass fiber is used.

Aramid Fibers: High strength, toughness and low density, BUT expensive. Low compressive strength, UV degradation and difficult to cut.

Carbon Fibers: High tensile and compressive strength, stiffness, low density, good fatigue response BUT very expensive. Fragile when subjected to impact and aesthetically attractive. Lightweight applications in which, stiffness and strength are crucial.