Polymer Classification

Most plastics materials used in the industry today fall into one of the three categories. These are the commodity, engineering, and specialty resins.
(i) Commodity Resins
Commodity resins are the least expensive and most commonly used polymers. These polymers are easy to produce and process. Commodity resins are materials such as polyolefins, polyvinyls, and polyureas.
Commodity resins typically have poor mechanical strength, and usually have only one useful property. For example, polystyrene has low mechanical strength, and poor impact and chemical resistance, but has excellent clarity.
Polyolefins are thermoplastics polymers such as polyethylene and polypropylene.
Vinylic polymers include thermoplastics such as PVC, polyvinyl alcohol, and polystyrene.
Phenolics are thermoset polymers, such as polyurea formaldehyde, and melamine formaldehyde.
(ii) Engineering Resins
Engineering resins are more expensive, and less commonly used than the commodity resins. Engineering polymers include thermoplastics materials such as nylon, polycarbonate, polyester, and PET, as well as themoset materials, such as certain polyureathanes.
Engineering polymers are more difficult to process and produce. Engineering resins are known for their good mechanical strength.
Each individual material usually has several particularly good properties। For example, polycarbonate has good mechanical strength, impact resistance, and clarity, but has poor chemical resistance, and fades in ultraviolet light.

(iii) Specialty Resins

Specialty resins are the most expensive, and least used type of polymer. These polymers are typically thermoplastics, and include materials such as PEEK, polysulfone, liquid crystal polymers, and flouropolymers. These polymers are difficult to process and produce.
Specialty resins are known for their high heat resistance, and each specialty resin has one or two excellent properties. For example, PEEK has very high heat resistance and mechanical strength, but is very expensive, and difficult to process.
Many specialty resins also have to be annealed after processing. Annealing involves the heat treating of the produced parts to reduce any stress within the part, which increases the long term part performance.
Your material supplier should be able to tell you whether or not your specialty material should be annealed, as well as provide the required annealing times and temperatures.