Feb 23, 2024

TPE vs. Silicone: Which is Best for Your Application?

Reading Time: 4 minutes

Thermoplastic elastomers are an essential material for manufacturing a wide array of products across automotive, medical, industrial and consumer sectors. When considering TPE vs. silicone, keep in mind that different thermoplastic elastomers have distinct characteristics that make them ideally suited to certain applications.

While products developed with these elastomers may have a similar appearance and texture, they possess distinct properties, which are a result of the specific material used.

For instance, TPE and silicone are both synthetic polymers that are commonly used in injection molding processes. Products made from liquid silicone rubber (LSR) have different chemical resistance than those made with TPE.  Conversely, TPE is often used for providing favorable tactile sensations while balancing the price point and processing.

Understanding the distinct processing behaviors and characteristics of TPE and silicone is vital to making an informed choice for your specific application.

Chemical Composition

TPE, also referred to as thermoplastic elastomer, is a hybrid material combining elements of both plastic and rubber. It achieves a semi-melted state when heated yet does not become a liquid. TPE can be modified with various materials to produce different grades, such as TPV (thermoplastic vulcanizate) or TPU (thermoplastic polyurethane), each with its own set of properties.

LSR is a thermoset characterized by its polysiloxane bonded molecular structure.  This composition grants distinctive qualities that TPE lacks.  The mechanical and material properties of LSR can be further enhanced by integrating other additives and functional groups to the siloxane polymer.

Moldability Differences

TPE and LSR react differently when exposed to heat. TPE, which often comes in pellet form, becomes malleable under heat. It is then shaped into components through pressure molding. Upon cooling,

it solidifies without forming chemical bonds, allowing it to maintain its chemical structure even after cooling. This consistency enables TPE to be reprocessed or recycled i.e., ground to pellet, melted down and re-molded. If exposed to high temperatures for prolonged periods of time the TPE will start to degrade.

LSR, a viscous silicone polymer, that forms a cross-linked bond when heated. This process creates a durable chemical bond that defines the product’s final shape once it cools. The cross-linking means that once LSR is set, the process is not reversible. However, this chemical bonding contributes to the significant strength and longevity of the finished product.

Performance Properties

Along with their diverse chemistries, TPE vs. silicone offers their own set of attributes.

TPE Pros

• Flexible: can be reused & reground
• Able to be remolded
• Recyclable
• Consumes less energy during production
• Easy to process using conventional thermoplastic methods such as injection molding, extrusion and blow molding
• Can be produced to a spectrum of hardness and toughness
• Abrasion resistant
• Moldable into virtually any shape

TPE Cons

• If exposed to high temperatures, it will melt after originally cooled
• Creeping and deformation can result under sustained pressure

One of the most significant benefits of TPE is its recyclability as sustainability becomes ever more important in preserving natural resources and the world.

LSR Pros

• High water, chemical and heat resistance
• Excellent compression set
• Excellent electrical insulation properties
• Excellent elasticity
• Biocompatible for clinical uses and creating nontoxic, nonallergenic parts
• High-precision manufacturability; can be made into parts with tight tolerances

LSR Cons

• Not recyclable and cannot be remolded
• Longer curing period
• Thicker in appearance

LSR offers properties such as resistance to heat, chemicals and temperature as well as biological compatibility that cannot be achieved with TPE. Offering greater thermal stability, the temperature range of silicone is -58 °F to 446 °F; temp stability is limited to -50 °F to 210°F for PTE. The table below compares important characteristics of LSR and TPE.

TPE vs. Silicone for Various Applications

Both TPE and LSR (silicone) are used across multiple sectors to produce components and commodities. Choosing one over the other depends on budget, performance requirements and the environment in which the product will be used.

LSR is pricier, yet delivers superior performance compared to other rubbers in the marketplace. Its biocompatibility makes it a preferred material in medical and health care sectors. Also, LSR’s purity and resistance to steam and high temperatures render it excellent for producing components in sterile ISO-certified clean rooms. Thanks to its low viscosity, LSR is capable of filling molds completely, allowing for the creation of intricate and complex shapes.

On the other hand, TPE is often chosen for its reduced production time and cost benefits, especially in applications where resistance to extreme temperatures and chemicals is less critical. TPE is particularly suitable for consumer goods that demand appealing aesthetics and fine surface finishes.

Common TPE Uses

• Sealrings
• Window gaskets
• Dashboard components
• Closure liners
• Bottle caps, baby bottles
• Surgical gloves, medical bags
• Phone covers
• Toys
• Footwear
• Soft-to-the-touch grips

Common LSR Uses

• Implants
• Medical tubing and device seals
• Surgical components
• Seals for disposable syringes
• Valves for IVs
• Liners for prostheses
• Hypoallergenic products such as hearing aids
• Keypad electronic interfaces
• Automotive, aerospace and industrial gaskets and seals

H.M. Royal supplies a variety of grades of Wacker’s Silpuran solid and liquid silicone elastomers that meet the high standards of the health care industry. Products fabricated from Elastosil & Silpuran are physiologically safe, resistant to heat and radiation, and biocompatible. Grades meet certain test requirements of ISO 10993 and the United States Pharmacopeia Class VI.

When considering TPE vs. silicone, remember that though they can look and feel similar, each has unique properties that make them suitable for different uses. Liquid silicone rubber is more chemically resistant and biocompatible, while TPE offers a better tactile feel. H.M. Royal understands their specific properties and processing behaviors, so we can help you select the best one for your application.

To find out more about our silicone elastomer products, contact an expert at H.M. Royal today.

Download this selection guide to help choose the best Wacker LSR Product for your application: