The properties of composites are dependent on the type, amount, and orientation of reinforcements that are selected for a particular service. Many materials are capable of reinforcing polymers. Although most commercial reinforcements are man-made, naturally occurring materials find use such as biomass.
There are many commercially available reinforcement materials and forms to meet the design requirements of the user. The ability to engineer the reinforcement architecture allows for the optimized performance of a product that translates to weight and cost savings.
Today, glass fibers account for more than 90% of the fibers used in reinforced polymers because they are inexpensive and have relatively good strength-to weight characteristics.
Reinforcements = Fibers
The majority of composites are manufactured with fibrous reinforcements due to their unique features:
Fibers have high mass-specific strength and stiffness as compared to bulk materials.
Textiles can be oriented to provide tailored properties in any direction.
Fiber reinforcements carry the load efficiently along the length of the fiber to provide strength and stiffness.
Main forms of fibrous reinforcement structures:
Woven, Stitched, Braided & 3-D Fabrics
Unidirectional tapes, tows
Chopped & Milled Short Fibers
Stronger than steel in certain forms
Transparent to radio signal
High-Performance Polymer Fibers
Extremely Tough, Lightweight
Aramids, UHMWPE, LCPs etc.
Damage / impact resistance
Heat, electricity insulation
Additives & Fillers
Additives are used in composites to modify materials’ properties and tailor the laminate’s performance. When added to the resin, fillers can reduce cost and improve properties including water resistance, weathering, surface smoothness, stiffness, conductivity, and stability.
Common fillers: calcium carbonate, kaolin, clays
Hollow glass beads