Why are thermosetting plastics used

For example, the thermoset plastic known as phenolic undergoes partial polymerization at the supplier. The supplier reacts under intense heat and pressure, and stops the chemical reaction at the stage of most of the linear chain formations. The final stage of vulcanization occurs in the molding press , where the unreacted portion of the phenol liquefies under heat and pressure, which creates a crosslinking reaction between molecular chains.

Traditional thermoplastics consist of vicious liquids that have a susceptibility to creep and deformation, which makes then unsuitable for many applications. Along with other characteristics, thermosets offer product designers chemically robust materials with a surface hardness and heat resistance, which exceeds that of thermoplastics. Material options include:. Many manufacturers are realizing the benefits of replacing traditional metal materials with thermoset. Thermosets have the characteristics necessary to meet demanding product specifications.

They also have a longer lifecycle and reliability. The material provides excellent value through improved performance at a lower cost. Product designers, engineers and managers have an ongoing mission to discover materials that have the properties and capabilities to meet very demanding performance requirements, as well as to save time and money. The use of LSR has been trending up since its introduction in the s, and has supplanted thermoplastic and other silicone materials for use in aerospace, food and beverage, automotive construction, communications, consumer products and more because of its superior durometer, elongation and modulus tear qualities.

Thermoset plastic products are typically produced by heating liquid or powder within a mold and allowing the material to cure into its hardened form. The molder can remove the part from the mold before it cools. The reaction used to produce thermosetting plastic products involve a chemical interaction between specialized materials. The depth of the screw flight decreases at the end of the screw nearest the mold, which compresses the LSR.

A check valve at the end of the screw facilitates high-pressure injection, by moving the screw forward — employing the screw like a plunger. This process is commonly used for products that require high precision, including seals, electrical connectors and medical applications. Many companies appreciate the high strength-to-weight ratio — thermoset components are up to 35 percent lighter than steel parts of equal strength.

This extremely strong material that offers ease of manufacturing and thermosetting materials provides a host of other characteristics at a low cost, including:. Although thermoset cannot be reheated and remolded, materials can be repurposed for other applications. For example, polyurethane foam can be shredded into small flakes and used for fabricating carpet underlayment. Though thermoset plastics and thermoplastics sound similar, they have very different properties and applications.

Understanding the performance differences can help you make better sourcing decisions and improve your product designs. The primary physical difference is that thermoplastics can be remelted back into a liquid, whereas thermoset plastics always remain in a permanent solid state.

Think of thermoplastics as butter — butter can be melted and cooled multiple times to form various shapes. Thermoset is similar to bread in that once the final state is achieved, any additional heat would lead to charring.

Thermoset plastics contain polymers that cross-link together during the curing process to form an irreversible chemical bond. In short, thermosets and their composites can be found in all markets and sectors. Utilizing the thermoset plastic manufacturing process , some great benefits of thermosetting materials are their light weight and flexibility. Thermoset composites remain stable in all environments and at many temperatures, too.

Parts are dimensionally stable and structurally sound, and can be processed at low pressures and viscosities with reinforcing composites such as fiberglass, carbon fiber, or Kevlar to produce an incredibly strong, durable material.

Osborne Industries, Inc. These materials see a wide variety of use in manufacturing products from clothing and non-stick cookware to carpets and laboratory equipment. Thermoplastics have seen common use in the injection molding process as they produce parts that are flexible, accurate and have aesthetically pleasing surface finishes.

Thermoplastics are also valued for their recyclability, as products created from them can be re-melted and formed into different shapes via the injection molding process. This has led to the popularity of thermoplastics in the toy, furniture and clothing industries, as it allows parts to be recycled and reformed after suffering damage, wear and tear.

The process of thermoplastic injection molding begins with the creation of a mold, usually from metal such as steel or aluminum. The thermoplastic resin is then melted into liquid form in a heated barrel before it is injected into the mold to cool as a solid. Once the part has fully set and cured, it is removed from the mold and the process is complete. However, thermoplastic injection molding requires high heat and high pressure in order to successfully create parts. For this reason, it is not always a cost-effective solution, especially for orders that require a high number of parts to be produced.

Thermoplastics are also ineffective for parts which are regularly exposed to extreme heat or rapidly varying temperatures, because of their ability to melt. In contrast to thermoplastics, thermosets alternately known as thermosetting plastics or thermosetting polymers are materials which remain in a permanent solid state after being cured one time.

Polymers within the material cross-link during the curing process to perform an unbreakable, irreversible bond. This means that thermosets will not melt even when exposed to extremely high temperatures. Common examples of thermoset plastics and polymers include epoxy, silicone, polyurethane and phenolic. In addition, some materials such as polyester can occur in both thermoplastic and thermoset versions.

Unlike thermoplastic pellets, the components of thermoset polymers are stored in liquid form, usually in large tanks or containers. Different thermosets provide different advantages when used as a production material. For example, epoxies are highly elastic, tough and resistant to many chemicals while phenolic is highly flame resistant. For a more in depth at the benefits of one popular thermoset, polyurethane, see our article here.