Material selection is an extremely crucial aspect for manufacturing high-quality plastic parts. When it comes to material selection for flexible plastics, two of the most popular and preferred materials are Thermoplastic polyurethane and Silicone. Both flexible plastics are versatile and have distinct properties and applications.
TPU demonstrates excellent abrasion resistance and flexibility. Silicone, on the other hand, is chemically inert and demonstrates flexibility across various temperature ranges, thus making it a preferred choice for biocompatible products and soft-touch applications. In this article, we discuss each material of TPU vs Silicone in detail, compare their properties, and understand their distinct applications.
Thermoplastic polyurethane, commonly abbreviated for TPU, is a type of thermoplastic elastomer that consists of polyurethane and polyester and is created through the reaction of diisocyanates with polyols.
Thermoplastic polyurethane is highly elastic and demonstrates excellent flexibility. It stretches significantly without breaking and retains its shape and integrity. These aspects make it an apt material for applications that require products to be resilient and flexible.
Since TPU is a thermoplastic, it is recyclable. It can be re-melted and reprocessed, thereby making it an environmentally friendly option.
TPU demonstrates excellent abrasion resistance. It offers tear and wear resistance, enhancing part longevity.
TPU is compatible with various manufacturing processes and can be easily processed through custom injection molding, extrusion, and other techniques. It is also highly moldable, thereby making it one of the most preferred materials for manufacturing for various industries.
TPU absorbs moisture quickly from the atmosphere. It thus, requires strict drying protocols to be followed before processing.
It’s chemically vulnerable as it’s prone to degradation when exposed to strong acids, and bases.
Thermoplastic polyurethane softens and degrades when it’s consistently exposed to higher temperatures of above 100°C/212°F. It is thus not ideal for continuous use in high-temperature environments.
Silicone is a synthetic elastomer that’s concocted from silicon, oxygen, carbon, and hydrogen. It’s known for demonstrating chemical inertness, biocompatibility, and ability to be functional across an array of temperature ranges.
Silicone is a biocompatible material due to its inert properties, which is why it’s commonly applied to manufacture healthcare and medical devices.
It’s an inert material that also resists chemical degradation which makes it a great material for manufacturing products that come into contact with food, liquids, pharmaceuticals, etc.
Silicone is weather and UV-resistant. This property makes it an excellent material of choice for outdoor applications.
Silicone is inherently a soft material. It also demonstrates excellent tactile properties.
Silicone can withstand high temperatures of typically up to 200°C / 392°F. Its high resistance to heat enables Silicone to maintain its properties under high temperatures.
It maintains flexibility at lower temperatures, as low as -60°C / -76°F. Thus, it’s ideal for applications that require the material to perform and be stable under very low temperature environments.
Silicone demonstrates hydrophobic properties. It resists moisture absorption, which is why it’s preferred for applications that require waterproofing.
It has excellent electrical insulating properties, and is thus an apt material of choice for the protection and insulation of electrical and electronic components.
Silicone demonstrates a lower abrasion resistance than TPU, which makes it unsuitable for applications that require the products to undergo continual mechanical stress.
Silicone is prone to wear and tear under mechanical stress. Thus, its applications are limited for high-pressure environments.
Thermoplastic polyurethane and silicone differ significantly in their mechanical properties.
Silicone is flexible and elastic. It demonstrates excellent fatigue resistance and is able to maintain its softness and resilience across various temperature ranges. TPU, on the other hand, demonstrates excellent abrasion resistance, flexural strength, and high tensile strength. It demonstrates superior tear strength and toughness that can withstand repeated mechanical stress. You should also note that TPU has better creep resistance than Silicone which indicates that it maintains dimensional stability under continuous loads. In terms of abrasion resistance, Thermoplastic polyurethane has a much lower DIN loss than that of Silicone, which is why it is better able to resist surface damage.
TPU performs moderately towards weak acids but is attacked in the presence of strong acids and alkaline conditions. Silicone, on the other hand, demonstrates excellent resistance in both acidic and basic environments. It is able to maintain its chemical integrity across a wide range of concentrations and conditions. Silicone also demonstrates excellence over TPU in terms of gas permeability, biocompatibility, UV, hydrolysis, and oxidation resistance.
Silicone has a broader service temperature range than TPU. In the case of temperature flexibility, Silicone demonstrates superior low-temperature elasticity, whereas TPU begins stiffening. In addition, TPU softens and loses its mechanical properties between 170–220°C / 338–428°F, whereas Silicone has no true melting point. Thus, Silicone is preferred for extreme condition applications.
In terms of long-term durability under heat, TPU is vulnerable to thermal aging. Silicone, on the other hand, can maintain elasticity and stability between 200–250°C / 392–482°F when exposed to prolonged time. TPU typically burns readily unless it’s formulated with flame-retardant additives, whereas silicone is naturally flame-resistant.
Thermoplastic polyurethane offers toughness and can be aesthetically pleasing which is why it is popularly applied to manufacture interior automotive components such as steering wheel covers, cup-holder inserts, and flexible trims. Silicone, on the other hand, is applied to manufacture HVAC seals and anti-vibration pads. You should note that Silicone remains elastic under extreme temperature shifts whereas TPU might stiffen or lose elasticity.
TPU demonstrates excellent impact absorption and scratch resistance, which is why it’s preferred in exterior automotive components for paint-protection films, and bumper covers. Silicone, on the other hand, demonstrates excellent resistance towards UV light, ozone, and moisture and is thus applied to manufacture exterior seals, gaskets, and wiper blades.
TPU is commonly applied for flexible tubing in fuel lines, protective cable jackets, and decorative films due to its excellent balance of chemical resistance, toughness, and processability.
Silicone is applied for more demanding thermal and chemical environments such as O-rings, high-temperature gaskets, and vibration isolators inside the engine compartment as it can withstand extreme heat and oil exposure.
TPU is moldable into highly flexible, durable forms, which is why it’s preferred for manufacturing fitness bands and smartwatch straps. Silicone, on the other hand, has a more soft-touch comfort. It’s applied to manufacture premium straps and skin-contact patches due to its hypoallergenic nature, and sweat resistance. You should note that both materials are flexible enough to be applied for wearable devices, but Silicone provides more comfort for prolonged hours of use.
In medical devices and components, Thermoplastic polyurethane is employed where flexibility, and transparency are crucial parameters. For instance: catheters, IV systems, and prosthetic coatings. Silicone, on the other hand, is applied for manufacturing implants and respiratory masks due to its excellent biocompatibility over long periods.
TPU is often applied for housings of diagnostic instruments or flexible connectors due to its toughness and resistance to repeated cleaning.
Silicone is ideal for surgical grips, reusable tubing, and seals that must endure sterilization cycles without hardening or cracking.
TPU is typically applied when toughness, abrasion resistance, and aesthetics are a priority. For instance: water bottles and protective phone covers. Silicone, on the other hand, is applied to manufacture products that are non-toxic and need to be flexible after repeated use. For instance: Baking molds, spatulas, and reusable containers.
TPU can endure impact which makes it the preferred choice for active-lifestyle products such as sports gear and accessories. Silicone is applied to manufacture products that are in prolonged skin contact due to its hypoallergenic, soft-touch nature. For instance: baby pacifiers, and skincare massagers.
TPU provides design flexibility and toughness, which is why they are applied to manufacture lifestyle accessory products such as transparent handbags and some parts of luggage.
Silicone’s elasticity and soft feel enhances user comfort and is thus applied to manufacture everyday reusables such as eco-friendly straws, and non-slip household grips.
TPU is popularly applied to manufacture transparent smartphone cases and screen protectors as it resists scratches while maintaining clarity. It gives products a rigid yet flexible structure that absorbs impact. Silicone provides a premium feel and grips surfaces well which is why it’s applied for soft protective covers, and dust caps.
Thermoplastic polyurethane is applied to manufacture jackets for cables and connectors due to its flexibility. Silicone on the other hand, is chosen for high-temperature connectors and insulation in environments such as industrial chargers or lab equipment. It doesn’t degrade under heat, where TPU might soften or fail.
TPU balances strength and design while reducing weight, which is why it’s applied to manufacture lightweight products for cabin interiors. Silicone is elastic in a wide range of temperatures which ensures safety and reliability and is thus applied to manufacture seals and gaskets that are often exposed to extreme altitude changes.
TPU is applied to manufacture protective films and hoses due to its flexibility and impact resistance. Silicone on the other hand, is applied to manufacture wiring insulation, high-temperature seals, and anti-icing coatings due to its stability.
TPU and Silicone demonstrate distinct properties and unique advantages. They cater to specific applications, and it’s crucial to understand the technicalities and unique properties of the material to consider them for your application.
VEM-Tooling has over 20 years of experience in manufacturing high-quality plastic parts and providing other manufacturing solutions. Our experienced engineers can guide you with material selection and help you understand which material is apt for your part.