Polymer matrix composite materials have become increasingly popular in recent years due to their ability to provide resistance to corrosion, heat, and impact damage. They consist of a matrix material (which is generally a thermosetting polymer) and fibers (usually a reinforcing agent such as glass, graphite, or carbon). The combination of the two creates a composite material with unique properties not found in either component alone.
The chemical composition of the polymer matrix is an important factor in the overall performance of the composite material. Polymers usually contain a variety of monomers, or repeating subunits, which provide the desired properties. Common types of monomers found in many matrix materials include epoxies, phenolics, acrylics, and urethane-based systems.
Epoxies are a type of thermoset, or crosslinked, polymers which are composed of epoxide groups. The epoxide group reacts with curatives, or catalyst agents, which initiate the curing process, resulting in a stable and durable matrix. Once cured, the epoxy matrix offers excellent mechanical and chemical resistance properties, making it a popular choice for matrix-based composite materials.
Phenolics are the second type of thermoset polymer that are commonly used in composite materials. Also known as phenoxy resin, phenolicsare created from the reaction of phenol with aldehyde. Phenolics exhibit good flame resistance properties and its ability to absorb energy makes it useful for applications where shock and vibration are of concern.
The third type of monomer commonly used in polymer matrixes is acrylate. Acrylate polymers are created from a reaction of acrylic acid with an initiator or curative. The resulting polymer matrixes are often found in adhesives, pressure sensitive tapes, sealants, and coatings. It offers excellent UV resistance, making it ideal for outdoor applications.
Finally, the fourth type of monomer found in many polymer matrixes is urethane. Urethane polymers are produced through the reaction of diisocyanate and a polyol. Urethane exhibits excellent properties such as flexibility, which makes it ideal for applications where it will be subjected to shear or dynamic loading.
The chemical composition of a polymer matrix can vary greatly depending on the specific application in which it is being used. For example, an epoxy matrix used in a composite material may contain multiple monomers such as epoxy, phenolic, acrylic and urethane, in order to provide the desired properties. In any case, knowing the unique properties of the individual monomers makes it easier for designers and engineers to understand and work with the resulting composite material.
