The Difference Between Thermoset and Thermoplastic Materials
Each application will have its own unique circumstances and requirements. For some, the ability to resist abrasion will be the top priority, while another might need a material that can resist extreme temperatures.
Choosing the right material for your application will be an involved process that takes every factor into consideration. In order to select the right one, you will need to understand the properties of the material you are selecting. That’s why we are going to take the time today to distinguish between the two biggest categories of elastomers: thermoset and thermoplastic.
Thermoset Materials
Thermoset materials simply refer to those plastics which will cure (or harden) into a certain shape once a sufficient amount of heat is applied. This heating process is called curing or vulcanization, and it is meant to improve the physical property of a certain material by exposing it to heat or some other catalyst which can set off a chain reaction within the material.
Before undergoing vulcanization, a thermoset material consists of small, unlinked molecules called monomers. But during the vulcanization process, these monomers develop permanent connections with each other called cross-links.
These cross-links will form long molecular chains which give the material a much more rigid three-dimensional structure. Once vulcanization is complete, the material can no longer be remelted or process the way it was prior to vulcanization. For this reason, thermoset materials are relied on for high temperature applications like electronics and appliances.
Thermoset materials possess a number of advantages over thermoplastic materials, including superior mechanical properties, chemical resistance, heat resistance, and structural integrity. They generally have a much lower material cost and are much easier to process.
Common thermoset materials include polyurethane and silicone. Polyurethane is well-noted for having the highest tensile strength (i.e. resistance to tear and abrasion) of any plastic. Silicone, on the other hand, is well-regarded for its ability to resist compression set, flames, and extreme temperatures.
Thermoplastics
Thermoplastic materials typically come in a pellet form which becomes soft, fluid, and pliable after vulcanization. The vulcanization process for thermoplastics involves placing the material in a heated cavity. After a time, the thermoplastics are removed and placed in a cool mold, where they harden into the shape of that mold.
Thermoplastics are incapable of forming the strong cross-links found in thermoset materials. As such, thermoplastics do not have the same kind of strength or structural integrity which thermoset materials possess. However, this also means that a thermoplastic material may return to its original form after being exposed to heat. Thermoplastic materials can do this multiple times, since they only undergo physical changes during vulcanization, rather than chemical. The number of times this can be done is limited due to the damage the material sustains in its vulnerable, molten state.
Most thermoplastic materials will possess high strength, shrink resistance, and are capable of bending. They are found in everything from plastic bags to high-stress mechanical parts.
Thermoplastic Elastomers
Sometimes, an application requires a material with a range of properties too wide for either thermoset or thermoplastic materials to handle on their own. This led to the development of another type of plastic. Thermoplastic elastomers (or TPEs) are materials which combine the strength of a thermoset material with the processing advantages possessed by thermoplastic materials. They are primarily made of hard phases, with softer phases dispersed throughout. These soft phases consist of cured thermoset particles, while the hard phase consists of a thermoplastic. Though their versatility is unmatched, it also comes at a much higher price.
Whatever You Need: Thermoset, Thermoplastic, or TPE
No matter whether you need the strength of a thermoset material, the bending ability of a thermoplastic, or a unique application that requires both, Real Seal will have a material that will fit the needs of your application.
Give us a call today, and our full-time chemist will help you choose a material using his expertise and experience to produce the perfect component for your application.
