TPE vs. Silicone and Their Differences

When you’re manufacturing with plastics, thermoplastics, rubbers, and elastomers, rarely will you ever have the problem of not having enough choice. The issue tends to be choosing which material of the thousands out there has all the properties you need—especially when some are so similar. That’s often the case when you’re weighing up thermoplastic elastomers (TPEs) and silicone, so let’s get into what makes each different and the applications where they’ll really shine.

What is Thermoplastic Elastomer (TPE)?

Manufacturers tend to opt for TPEs when they’re after a material with a blend of plastic and rubber properties. This synthetic rubber has excellent elasticity and a high melting point. It can be heated up, stretched, and returned back to its original shape before going through the whole process again.

It’s these properties that have given TPE a name in manufacturing, and why it’s often compared to silicone, as they share a few properties—but equally have quite a few differences. When you’re choosing a TPE to work with, you’ll find it’ll be based on how you’re processing or manufacturing it. For instance, there are TPEs for blow molding, extrusion, and injection molding.

What is Silicone?

Silicone may look and act a bit like rubber, but it’s much more complex. This synthetic material is made up of a bunch of oxygen-silicon molecules (called siloxanes) and it’s a popular pick that manufacturers still like using today. Like TPE, it has elastomeric properties, too.

There are a few cases where silicone falters—it’s not particularly well suited when up against steam, hydrocarbon fuel, or specific types of hydrocarbons, like those that are alkali, acidic, or aromatic. Still, those reasons shouldn’t be enough to put you off, as it’s a very common material used across plenty of sectors.

What is Thermoplastic Elastomer Made of?

A thermoplastic elastomer material is in a class of copolymers or a physical mix of polymers, which is usually a plastic and a rubber, that are made of materials with both thermoplastic and elastomeric properties. A thermoplastic elastomer is, therefore, a mix of plastic and rubber.

What Material is Silicone Made of?

Is silicone rubber or plastic? Scientifically, silicone lies in a gray area but is generally considered a rubber. It’s a human-made elastomer with both plastic and rubber properties. Silicone can be used to form liquids, hard solids, and rubbery products, but since elastomers are generally referred to as rubbers, it’s also usually referred to as rubber. Silicone is also easily confused with silicon, though they are different materials. Silicon is an element, while silicone is a polymer (a large molecule with repeating units).

What is the Product Performance of TPE and Silicone?

TPE and silicone both make high-quality products. Silicone products have exhibited excellent properties, such as thermal conductivity, fire resistance, good chemical stability, flame retardancy, and excellent resistance to heat and cold, etc. TPE products are extremely versatile, naturally chemical resistant, cost-effective, and have outstanding thermal properties and material stability.

What is Thermoplastic Elastomer’s (TPEs) Melting point?

The temperature resistance range of TPE is theoretically 130 to 150C, and above that range, TPE will age and crack. Thermoplastic elastomer has a melting point of 260-320C.

What is Silicone’s Melting Point?

Silicone does not have a melting point. It remains solid until combustion occurs. At high temperatures (200-450C), silicone rubber will slowly lose its mechanical properties over time, becoming brittle. The temperature resistance range of silicone is considered to be 200 to 300C.

What is the Process of TPE and Silicone Injection Molding?

Both of these rubber-like materials are great when it comes to injection molding processes. For silicone injection molding, you’ll need a molding tool made with CNC machining that has an excellent heat-resistant finish in order to mold silicone—especially with its wild ability to handle high temperatures without degrading or melting. Once you have this tool made, it’ll be added to a press that can create precise shots of material. From there, tons of different items can be made with silicone injection molding, including cooking utensils, gaskets, and prosthetics.

When Should You Use Thermoplastic Elastomer (TPE) and Silicone?

The main difference between TPE and silicone is how they react to heat. After TPE is heated, it can be reprocessed. If you’re deciding between thermoplastic elastomer and silicone for a product, and it needs to be reprocessed, you should choose TPE. Silicone cannot be reprocessed or altered after heat has been applied.

Suppose you’re deciding between thermoplastic elastomer and silicone for a product that needs to withstand extremely high temperatures. In that case, silicone is the better option, as its temperature resistance range is much higher than TPE’s.

How Do I Choose the Right TPE Materials?

When you’re thinking of using either TPE or silicone, you’ll want to take stock of each of their characteristics and what they both excel at (and aren’t so great at). Silicone is great if you need products that will have good thermal conductivity and have good resistance to fire, heat, and cold. It also has a remarkable quality that’s hard to find in any other plastic or rubber—it doesn’t have a melting point. It’ll either combust or turn brittle after 450 ℃.

In this instance, thermoplastic elastomers are a good alternative as items made of this material are affordable but still have good chemical resistance, stability, and heat resistance. TPEs, of course, have a melting point, too, but a pretty high one. The biggest deciding factor in many scenarios is twofold. If you need a product that can be heated and reprocessed, you’ll want to go with TPE (silicone can’t do this), but if extreme heat resistance is the biggest priority, silicone is the winning material.

How Do I Choose the Right Silicone Material?

When choosing the right silicone, you should consider the required properties for the product’s intended purpose. The reality is there is no one single type of silicone that should be used for everything. Instead, many different types have different flexibility, durability, and resistance.

Consider the desired chemical, mechanical, and physical properties.

Where Can I Buy Silicone and TPE Materials?

Xometry can injection mold a variety of materials, including thermoplastic elastomers and silicone. Xometry also works with other thermoplastics, Engineered Thermoplastic Polyurethane, and liquid silicone rubber.

Is Thermoplastic Elastomer (TPE) Safe To Use?

Yes, it is safe to use thermoplastic elastomers. TPE is less likely to cause allergic reactions than latex. However, some people are concerned about the safety of TPE because it contains chemicals called phthalates. Phthalates are added to TPE to make it more flexible, but they can also harm human health.

Studies have linked phthalates to hormone disruption, reproductive problems, and cancer. However, it is essential to note that the levels of phthalates in TPE products are generally low and pose minimal risk to human health. As a result, TPE is legal to use and generally considered safe.

Is Silicone Safe To Use?

Yes, silicone is safe to use. Silicone is used for medical, electrical, and other applications. Because silicone is chemically stable, experts say it’s safe and likely not toxic. Additionally, according to the FDA, food-grade silicone cookware does not cause harmful chemical contamination of foods.

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