Composites have been used successfully in sports, recreation and marine applications for several decades in areas such as winter sports equipment, golf, protective gear, mass structures, super yachts, work boats and leisure craft. More recently composites have been used in less well-known applications such as Olympic sports gear, off road vehicles, bearings, propellers, commercial hatch covers and boat exhausts. However, despite the many advantages that composites offer, there are still many perceived disadvantages of using composites.

Composites are difficult to repair

The belief that composites have poor reparability stems from the fact that composites are amorphous or heterogeneous materials in which certain properties like strength and stiffness are aligned in one or two directions. This is not the case with metals which are malleable and are homogenous. However, of the reasons people choose fiberglass boats and composite sports equipment overwhelmingly over other types of construction is the ease that damage can be repaired. Once a part is damaged, all repairs become secondary bonds attached to the original primary structure. This means all repairs are dependent upon physical bonding to the surface of the original primary structure. For this reason, fiberglass repairs rely upon the adhesive quality of their resin for their strength—the strength of physical bond to the primary structure. Because of this, the resin used for the repair should be just as strong as the resin used to fabricate the part. In fact, resins with strong adhesive properties are sometimes used for repairs.

Composites can’t be recycled

Many composite parts are made from cross-linked polyester and glass fiber. The molecular bonds between the two substances are very strong, but difficult to separate. However, a number of industries haven shown that techniques such as pyrolysis and solvolysis have potential to reclaim fibers, and techniques such as combining ground up composites and new material has shown promise as well. Another approach the industry has taken is to see energy conversation as the baseline technology of recycling instead of trying to reclaim individual fibers. In that approach, the fuel byproduct from the recycled composite can contain value.

Raw materials for composites are too expensive

The cost of composites (both in terms of raw materials and fabrication) has come down considerably from yesteryear. While composites may still have a higher initial upfront cost than competing materials, their maintenance and installation costs are lower over time, not to mention high performance vehicles and equipment simply cannot be made with the ultra-lightweight and ultra-strong advantages of composites.