Composites World magazine recently published a story about a UK project dedicated to creating high-performance discontinuous fiber (HiPerDiF) composites in hopes of improving composites in general. For the project to make any sense, you need to know what a discontinuous fiber composite is. Explaining it is the purpose of this post.
Discontinuous fiber composites represent an emerging trend within the larger composites sector. These new composites, when perfected, could open up an entirely new market for recycled composite waste. They could bring down the overall cost of composites too. For this reason, HiPerDiF composites are viewed by some in the industry as the most exciting thing to happen in a long time.
Here are the top four things to know about discontinuous fiber composites:
1. What They Are
Discontinuous fiber composites are composites made with fibers that are not connected in a long continuous fashion, like carbon fiber thread or tow. Rather, the fibers are much smaller pieces very similar to shredded cotton thread. The individual fibers can be part of a matrix in random fashion or purposely aligned to provide strength in a specific direction.
2. How They Are Made
Discontinuous fiber composites are made in a fashion similar to their continuous cousins, explains Salt Lake City-based Rock West Composites. The fibers are added to a polymer resin that will eventually be cured to create a single material. However, that’s where the similarity ends.
A continuous composite substance starts with either a thread or a woven fabric created from that thread. We will use carbon fiber fabric as an example. The fabric is laid in a mold, then combined with epoxy resin before being put into a high heat autoclave to cure.
A discontinuous product can be created in many different ways. Engineers can use spray layups, an injection process, 3D printing, or even casting.
3. What They Are Used For
To the extent that discontinuous fiber composites are currently being used, they are primarily for applications that do not require maximum structural rigidity. A good example is manufacturing carbon fiber frames for sunglasses. Those sunglasses don’t need to withstand the same kinds of forces as an airplane flying at 30,000 feet. Thus, the discontinuous fiber composite is appropriate.
Discontinuous fiber products are also used in the automotive industry for nonstructural parts. They are used to create interior components for sound systems, dashboards, etc. They may be used externally to create aesthetic parts like rear spoilers.
4. Why They Matter
The most important part of this discussion is why discontinuous fiber composites matter in the modern era. Quite simply, it is all about money. The composites industry has been in search of ways to produce composite parts at a lower cost for years. At the same time, they’ve been looking for a cost-effective way to recycle carbon fiber waste. Discontinuous fiber composites represent the answer to both.
Discontinuous fiber products can be made from recycled waste. Imagine all of the carbon fiber waste produced by an aerospace company like Boeing. That waste can be chopped and shredded before being put through a process to separate fibers from resin. The resulting fibers can then be used to create discontinuous fiber composites.
This makes for cheaper composites for applications that don’t require virgin continuous carbon fiber. Lower prices will encourage more manufacturers to embrace discontinuous materials, with the sales thereof boosting bottom lines and bringing the cost of continuous product down as well.
Discontinuous fiber composites will ultimately lead to more recycling and reduce the overall costs of manufacturing with composites. That’s what makes them so exciting.