When designing a new product that requires elasticity and a premium feel, engineers or procurement managers may encounter a critical choice: TPE or Silicone?
Although they are similar in tactile sensations, selecting the wrong material may cause product failure in many aspects. Therefore, it is significant to understand their differences. This article is dedicated to comparing them.
Introduction
What is TPE?
Thermoplastic elastomers are recognized as high-performance functional materials possessing plastic processing characteristics in the field of materials science.
From a microstructural perspective, you can visualize TPEs as a multiphase segregated structure with hard and soft segments. This unique block copolymer physical structure enables your TPEs products to exhibit outstanding physical crosslinking elasticity at room temperature. And when you heat the material to reach its melting temperature, TPE softens and becomes flowable. This allows it to be quickly injection molded under high pressure into the desired shape, with very short cycle times.
Unlike the traditional rubber, you don’t need chemical vulcanization when using TPE. Its molecular chains spontaneously rearrange upon cooling. This characteristic not only enables your material to be 100% recyclable but also provides you excellent base material compatibility for complex 2-color injection molding processes.
What is Silicone?
Silicone, academically known as polysiloxane, is a special elastomer with a semi-inorganic structure. Unlike TPE with its carbon-chain backbone, silicone’s core consists of an inorganic main chain formed by alternating silicon-oxygen (Si-O) atoms. This backbone structure with exceptionally high bond energy endows your material with outstanding thermal stability and chemical inertness.
During your production process, silicone rubber must undergo the vulcanization, where permanent chemical bonds can be established by a catalyst between polymer molecules. Once the crosslinked network forms, the silicone transforms into a typical thermosetting material with exceptional compression set resistance. Even under the extreme high or low temperatures or when you expose it to strong chemical reagents, its three-dimensional network structure maintains stable physical properties without melting or flowing. Such high molecular stability also makes it the gold standard for your biocompatible materials.
Comparisons of TPE and Silicone
Physical and Chemical Properties
When you select the elastomer materials, you will realize a single hardness indicator is often insufficient to support decision-making. The key to ensure the quality of the products contains many factors, including your understanding of the molecular behavior of the material under extreme pressure, temperature fluctuations and long-term service conditions.
Heat Resistance
You may notice the most significant performance distinction between TPE and silicone lies in thermal stability. Due to its high-energy Si-O bond backbone, silicone maintains nearly constant physical properties across an exceptionally wide temperature ranging from -40℃ to 250℃. This outstanding thermal stability makes it the optimal choice for automotive engine seals, high-temperature baking utensils, and industrial-grade heat-resistant seals.
In comparison, as a thermoplastic material, TPE exhibits significant performance fluctuations under varying temperatures. Although you can source some certain specialized grades of TPE that can withstand short-term exposure to temperatures ranging from 120°C to 150°C, you must be aware that prolonged exposure to high temperatures may cause the material to creep or soften.
However, TPE excels at low-temperature flexibility, maintaining excellent rebound elasticity even in extremely cold conditions without exhibiting glass transition brittleness like certain synthetic rubbers.
Hardness and Tactile Feel
In Tactile Engineering, Shore Hardness Range serves as your benchmark. The hardness spectrum of TPE ranges widely, spanning from ultra-soft gels(Shore 000) to near-plastic hardness(Shore D). In terms of touch, TPE is often described as dry or silky smooth, providing you a comfortable and non-sticky touch that is well-suited for handled and user-contact components.
The hardness of silicone you encounter usually ranges from Shore 30A to 70A. Compared with TPE, silicone tends to feel softer and more rubber-like at the same hardness level, with a slightly tacky surface texture that is often preferred in applications where grip and friction are important.
Elasticity
Although silicone cannot achieve extreme low hardness like TPE, it possesses unique strength and a high elastic recovery rate. From the microscopic level, you will find the compression set resistance of silicone significantly outperforms TPE. Therefore, the silicone can rapidly return to its original shape after prolonged compression, delivering sustained sealing force, whereas TPE is prone to permanent deformation under long-term stress.
Lifespan
The service life of your material depends on its resistance to environmental factors.
With unparalleled aging resistance that chemical inertness and oxidation resistance endows, silicone exhibits exceptional resistance to ozone, ultraviolet radiation and extreme climates. Even after years of exposure to direct sunlight outdoors, its physical properties keep stable.
With the structure of the carbon chain, TPE is relatively sensitive to ultraviolet light and specific chemical solvents such as certain oils and organic solvents. Although modern TPEs can extend their lifespan through the addition of UV stabilizers and antioxidants, silicone rubber still holds an absolute advantage in terms of physical performance durability under extremely harsh outdoor conditions or in industry environments involving contact with strong chemicals.
Manufacturing and Cost Analysis
In the decisions of selecting material, physical properties are often just the tip of the iceberg. As a project leader, you must thoroughly evaluate the total cost of ownership(TCO) because the differences of production logic can determine your capital expenditures and long-term operational returns.
Production Efficiency
If you pursue higher turnover rates, TPE would be a reliable partner for your project. As a thermoplastic material, TPE allows you to leverage existing efficiency injection molding processes with single-cycle injection time ranging from 30 to 60 seconds. That means you can keep a high speed operation in your production line, fulfilling massive orders in minimal time.
In contrast, you need to reserve a longer period if you choose silicone. Whether using liquid silicone rubber(LSR) or solid silicone rubber, the vulcanization process is a must in the mold. In order to ensure your products’ molecular chains are fully cross-linked, the injection molding cycle typically extends to 2 to 5 minutes.
If you’re handling a consumer project with high volume, this distinction in production can affect your delivery times and labor costs per suit unit produced.
Tooling and Secondary Operations
In the process of mold development, you’ll also notice distinction between them. Silicone injection molds must withstand extremely high pressures and precise temperature control, which often means you need to pay higher costs for precision CNC machining. Additionally, you may need to arrange extra post-processing steps like deburring or secondary vulcanization, both of which increase labor expenses.
Things become much simpler if you choose TPE. Due to TPE’s high compatibility of process logic and standard plastics like PP or ABS, you can achieve overmolding easily, combining a rigid skeleton with a soft overmold layer on the same machine. It not only eliminates the hassle of purchasing adhesives and manual assembly but also makes your product structure more reliable.
Waste and Material Economics
The raw material consumption is another point you should take into consideration.
Silicone typically carries a high unit cost exceeding 30,000 RMB per ton and it cannot be recovered once molded. Your production waste, overflow material or defective products can only be discarded as industrial waste.
When using TPE, however, the raw material utilization rate reaches 100%. All the production waste can be reground and reintroduced into your next production run. For cost-effective projects with tight profit margins, the zero-waste capability of TPE becomes a powerful tool to boost profitability.
Application Comparison
Maternity and Baby Products
Choosing Silicone
If you’re designing baby bottle nipple, pacifiers or tableware, silicone is commonly regarded as the industry standard. It possesses excellent thermal stability, allowing parents to repeatedly boil or steam sterilize items at high temperatures without ever developing odors or leaching harmful substances. For these applications, high-precision components like a silicone nozzle or custom silicone adapter are often essential.
Choosing TPE
If your design focuses on slip-resistant overmolding for baby bath tubs, stroller handles or early learning toys, TPE is the smarter choice. Not only can it offer a wide range of vibrant colors, but also seamlessly integrates with rigid plastices through a 2-shot molding process, significantly reducing your assembly costs.
Wearables and Electronics
Choosing Silicone
In this field, silicone stands out with its naturally hypoallergenic properties and silky-smooth wearing experience, making it suitable for high-durability sealed buttons. It is also an ideal choice for precision gaskets and seals that cushion and protect internal components. These components directly impact the product’s quality and lifespan.
Choosing TPE
When faced with significant cost pressure and the need to produce a high-volume sports band, TPE is your best choice. It maintains outstanding elasticity while enabling faster market entry through shorter processing cycles.
Medical Device Engineering
Choosing Silicone
In the medical fluid management system, tubings that come into prolonged contact with human tissue must be constructed from materials that offer exceptional biocompatibility, flexibility, and resistance to kinking. Silicone tubing, with its pure and stable properties, ensures sterile and reliable fluid delivery while minimizing irritation to patient tissue.
Choosing TPE
It is a smart choice for single-use medical supplies such as syringe plunger seals, infusion bag connectors or tubing. And they have a high output ratio and ease of processing, which can save you significant costs in mass production.
Safety and Compliance
No matter how outstanding your product design may be, it cannot reach your target users without passing stringent industry certifications. There are three dimensions you can assess from: chemical inertness, biocompatibility and international standard certifications.
Silicone
If you seek for ultimate in chemical inertness, silicone can be your ideal choice because it contains no phthalates, BPA or latex, and it rarely causes allergic reactions when in contact with skin or food.
Food Contact Certification:
To make your products pose no risk of chemical migration under boiled at high temperatures or exposed to acidic foods, the silicone should meet U.S. FDA 21 CFR 177.2600 and Germany’s stricter LFGB standards.
Medical-Grade Compliance:
For your medical device projects, silicone is a frequent candidate for ISO 10993 biocompatibility testing. It can withstand repeated autoclaving without degradation, making it ideal for long-term implants and complex surgical instrument handles.
TPE
Unlike the silicone with relatively pure ingredients, the safety of TPE heavily depends on the formulation you choose. You must work closely with suppliers to ensure their formulations contain no prohibited plasticizers or heavy metals.
The Rise of Medical-Grade TPE:
You may notice that an increasing number of USP Class VI Grade TPEs are entering the market. Designed for single-use medical consumables, this material now offers safety comparable to silicone.
Consumer Product Safety:
When developing children’s toys or personal care products, you can specify TPE compliance with EN71-3 (toy safety standard) or environmental regulations like REACH/RoHS.
Sustainability
While pursuing exceptional performance, you may also take consideration into the product’s environmental footprint. As a responsible designer, you must weigh up the end of life and production consumption.
TPE: Recyclable and Low-carbon Material
TPE is fully recyclable. The waste and components it produced can be melted and reshaped, which creates a close-loop cycle, reducing the cost and footprint. In addition, the processing temperature is lower than silicone, making it more energy-sufficient and environmentally friendly.
Silicone: Durable and Eco-Friendly Material
Though it is difficult to recycle conventionally, silicone embodies eco-friendness through longevity and durability.
FAQs
Q: Is silicone a type of plastic?
A: It is a common misconception. Silicone is not plastic. Actually, it is a synthetic rubber with an inorganic siloxane backbone. Although it can be processed as plastic, it lacks the thermoplastic properties of plastic, which means that it doesn’t melt when heated. And when it burns, it produces white silica smoke rather than toxic black smoke.
Q: Do they retain odors when contacting food?
A: Silicone possesses high chemical inertness and typically does not absorb odors. In contrast, containing carbon chain structures, TPE readily absorbs oils and odor molecules from food. If your project involves containers designed to hold spices or greasy foods long-term, silicone provides more lasting freshness.
Q: Can the silicone or TPE be painted?
A: TPE exhibits good surface polarity, making it relatively easy to spray or screen print. Silicone, however, has extremely low surface energy, making it difficult for standard inks to adhere. If you need high-quality surface painting, silicone typically requires flame treatment or uses expensive specialized inks, resulting in significantly greater processing challenges than TPE.
Q: Does TPE or silicone support laser marking?
A: TPE is highly suitable for laser marking, clearly presenting the logos or serial numbers. While silicone also can be marked, the results are typically less sharp than on TPE and often require special photoactive additives to achieve high contrast.
Q: Are they resistant to common solvents like alcohol?
A: Silicone shows exceptional inertness to common solvents such as isopropyl alcohol. While TPE remains unaffected during brief exposure, prolonged immersion in alcohol or strong cleaning agents may cause swelling or surface cracking.
Q: What are the differences between their sterilization methods?
A: Silicone can be fully compatible with autoclave sterilization. However, due to its thermoplastic nature, TPE is prone to deformation under high-temperature sterilization. Therefore, it is typically sterilized using gamma radiation or ethylene oxide(EtO).
Q: Why does TPE feel sticky after long-term use?
A: This is typically caused by the migration of plasticizers within the TPE formulation or physical degradation due to exposure to skin oils and cleaning agents. For silicone, it is nearly impossible to exhibit this migration or stickiness due to its stable molecular structure, resulting in a significantly longer service life compared to TPE.
Final Thoughts
In the debate of TPE vs. Silicone, the right choice depends on balancing your project’s performance needs with production efficiency. At legensilico, we specialize in helping you navigate these complex material decisions. Whether you need medical-grade precision or durable consumer solutions, our experts are ready to provide the technical support and high-quality materials your innovation deserves.
