Composite materials, also widely known to “composites,” are materials composed of at least two components with significantly different physical or chemical properties that, when combined, form a new material with superior performance and with properties different from the individual components.
Etymology: Borrowed from Middle French composite, from Latin compositus, past participle of compōnō (“put together”)
Composite materials are microscopic or macroscopic combinations of two or more distinct engineered materials, non-miscible. The physical and chemical properties of each of the constituent materials remain distinct in the new material. The materials are separated by a distinct interface.
These constituent materials work synergistically to produce a composite material that has different properties when compared with the individual constituent materials. In essence, composite materials are heterogenous, combining a “matrix” and “fibers” as a reinforcement:
- As matrix, polymer resins are the most significant, in volume and value terms.
- The fibers have a considerable length-over-diameter ratio (or “aspect ratio”), excluding spherical or ellipsoidal “inclusions” (when these are added to polymers, the resulting materials are called “particle reinforced” materials). Continuous fibers have an infinite aspect ratio, discontinuous or short fibers have finite aspects ratios (ranging from 10 to many thousands); higher aspect ratios result in higher stiffness and strength of the composite.
- The “reinforcement” indicates that this phase has mechanical properties superior to those of the matrix in terms of stiffness, strength and toughness
Manufacturing & Technologies
Composites are usually made with a combination of the following materials:
- Reinforcement fibers such as glass fibers, carbon fibers, aramid, basalt, or natural fibers like flax, hemp, bamboo…
- Matrix materials such as polymer resins, bioresins, concrete, ceramic…
- Additives and finishes enabling this combination and/or providing additional properties
Polymer composite products are manufactured using various processes and technologies, such as resin transfer molding, infusion, pultrusion, filament winding, fiber placement and more recently 3D printing. Simulation, automation and testing also play an important role in optimizing the development and manufacturing processes and in ensuring the highest levels of quality and performance.
The various combinations of materials, manufacturing processes, finishes and all the technologies involved in the composites industry offer an almost unlimited range of possibilities for end-users in all markets.
Milestones in the History of Composites:
50 Years from now. Composites Past, Present & Future:
JEC Group commissioned Ignaas VERPOEST, Emeritus Professor at the Composite Materials Group of the Department of Materials Engineering, Katholieke Universiteit Leuven, to document the history of composites and its key milestones and achievements. Focus is on the most important breakthroughs (“disruptive” innovations). The hundreds of “incremental innovations” in academia and industry have been important as well but describing them all would lead to a few hundreds of pages.
Ignaas VERPOEST was assisted by an international advisory board consisting of Frédéric REUX, Editor in Chief, JEC Composites Magazine; Franck GLOWACZ, Innovation Content Leader, JEC Group; Dale BROSIUS, Chief Commercialisation Officer, Institute for Advanced Composites Manufacturing Innovation (IACMI), Kenichi YOSHIOKA, General Manager Composite Materials Research Laboratories, Toray Composites and Christophe BINETRUY, Professor, Ecole Centrale de Nantes.