Resins

This phenolic resin insert is extremely versatile because of its light weight, density, structural strength, and resistance to heat and moisture.

Polymer resins are generally grouped into two categories, thermoset and thermoplastic. The main difference between these two classes of resin is their malleability after processing. Thermoset resins are initially liquids or solids with a low melting point that are cured using heat, a catalyst, or both in combination; once cured, thermoset resins cannot be converted back to their original form. In contrast, thermoplastic resins require no curing, can be recycled, and are able to be shaped or molded as they soften when heated.

Thermoset resins are used by MMC in their fiber-reinforced polymer products. Some thermoset resins identified by the Composites Institute are: unsaturated polyester resins, epoxies, vinyl ester, polyurethanes, and phenolics. Resins are often chosen for their specific functionality, for example polyesters can be tailored to fit the needs of a particular application. Characteristics of specialty polyesters can include flexibility, corrosion resistance, heat resistance, fire retardation, translucence, and others.

Resins offer good resistance to water and other aggressive substances along with the ability to withstand constant stress cycling.

Thermoplastic resins are inherently tough and resistant to impact damage. There are a wide variety of thermoplastic resins, each with its own advantageous properties. Some of the most popular thermoplastic resins are: nylon, liquid crystal polymers, polyetheretherketone, polypropylene, polyethermide, and fluoropolymers. The large number of choices in thermoplastic resins allows for many potential applications, however when evaluating the potential for a set of specific requirements the burden placed on an engineer or designer can be large as they must understand the relative characteristics and other physical attributes of the materials, and also consider compatability, performance and cost issues.