Silicone is a material that is widely used in industrial manufacturing, food production areas, and more, but few people really understand it. Are you still worried about the safety of silicone material? Do you want to know if it is suitable for your products? Follow this article to learn more about silicone materials and make the right judgment.
What Is Silicone Material
Strictly speaking, silicone material is a generic term for a class of silicone-based polymers that includes silicone oil, silicone resin, silicone rubber, silicone gel, etc. In fact, in automotive, medical, and other fields, most people refer to silicone rubber, rather than the strict definition of silicone material.
Silicone rubber is a synthetic rubber, sometimes called silicone elastomer. Its special molecular skeleton consisting of silicon and oxygen gives it advantages such as high temperature resistance and stability, while the organic groups attached to the skeleton determine the type of silicone rubber and its properties. These backbones are linked together to form a complex three-dimensional lattice structure, which also gives silicone rubber its high elasticity.
Where Does Silicone Material Come from?
The initial raw material for silicone is typically quartz sand. Unlike ordinary sand, this is a screened, high-purity silica raw material. In general, the higher the quality of the silicone, the higher the purity of the quartz sand used.
After heating, hydrolysis, and polymerization, polydimethylsiloxane (PDMS) is obtained. The low molecular weight PDMS is the main ingredient of silicone oil and heavier raw silicone.
Add fillers, additives, vulcanizing agents to the raw silicone rubber and mix it well, vulcanize it, and it becomes the various silicone products you usually see.
If you would like to learn more about silicone formulations, you can read What Is Silicone Made Of? How Compositions Affect Safety and Performance.
Characteristics of Silicone Materials
Wide Temperature Tolerance Range
Thanks to a strong silicone oxygen skeleton, silicone material can remain flexible over a wide temperature range. It’s not afraid of the high temperatures that plastics fear, and can withstand temperatures as high as 230°C, and phenyl silicone rubber(PVMQ) can even withstand 300°C for a brief period of time.
This makes it useful not only in industrial manufacturing at room temperature, but you can also find it in food baking tools and even aerospace seals.
It also has excellent low-temperature resistance, is less likely to become brittle, and can operate at -60°C. Phenyl silicone rubber is even more dramatic in this regard, and you’d be hard-pressed to think that a common material could actually be flexible at 100°C.
Recommended reading: Temperature and Silicone: What You Need to Know.
Chemical Compatibility
Another major advantage that silicone’s molecular structure gives it is chemical stability. It rarely reacts with other substances, and this includes the common household items as well as industrial materials like water, most car coolants, grease, weak acids and bases like citric acid and baking soda.
Still, it will inevitably corrode when it encounters some chemicals. As well, when confronted with chemicals like petroleum, silicone will gradually expand until it fails. Therefore, it is not recommended to use silicone materials for long-term contact with the following substances:
- Hydrocarbon fuels
- Some solvents
- Strong bases and strong acids
- Aromatic hydrocarbons
Fluorosilicone rubber (FVMQ) gets along with a wider variety of chemicals and is more resistant to corrosion, so it can be used in automotive fuel systems.
Weather Resistance
Silicone is used outdoors in a variety of products and projects for its excellent weather resistance. It is highly resistant to UV, which means that it is less likely to deteriorate under constant sunlight. Unlike PVC and rubber, which tend to yellow easily, UV has a much harder time destabilizing the molecular structure of silicone for “ultraviolet degradation”.
It is also more resistant to ozone, a chemical that accelerates aging in outdoor environments. What‘s more, the humidity and frequent temperature changes found in outdoor environments are difficult to affect silicone. All of this makes silicone more adaptable to outdoor environments and gives it a longer service life.
Flexibility
Silicone is a soft material and its flexibility can be customized for different needs. Its hardness ranges from 25 to 80 Shore A, which means you can find silicone materials that are as soft as Play-Doh or you can get silicone rubber that is harder like oak.
It has a tensile strength of between 200 and 1500 PSI, depending on the flexibility. It’s also less prone to cracking, and those silicone materials that are most flexible can be stretched up to seven times their own length without breaking.
Because of this flexibility, it is often used for cushioning and shock absorption. It is difficult to deform under frequent external pressure, and will slowly return to its original shape after the pressure is gone.
Wear Resistance
Silicone has a certain degree of abrasion and tear resistance, but it is weaker compared to materials such as rubber. Its physical and mechanical strength has to be reinforced by fillers and additives, etc. It is not recommended to use silicone materials in areas that are exposed to long-term friction or sharp knives. However, for most products, such as everyday consumer goods or pipes, silicone is perfectly suited for the job.
Permeability
In reality, silicone material doesn’t completely insulate and seal, because it is permeable. This is not to say that it will leak like cloth, but it doesn’t completely block the slow leakage of small molecules of chemicals, such as oxygen and water vapor when confronted with them.
The reason for this permeability is that there are very small gaps in the middle of the three-dimensional lattice structure of silicone molecules through which these gases may slowly escape to the outside.
The permeability of silicone materials is a double-edged sword. When being made into a wound dressing, permeability allows for faster recovery while insulating the wound from outside bacteria. But if you’re looking to use it to achieve a vacuum inside your machine, there may be no way for the silicone to reach your expectations.
Don’t worry, this permeability is generally only noticeable when used over a long period of time and used to seal some chemicals. In addition, you can reduce permeability by surface coating and adding other fillers.
Electrical Insulation
Silicone material has a very high ability to block the passage of electric current. With a resistivity of 10¹³ Ω-cm to 10¹⁵ Ω-cm, it provides effective protection against electrical leakage that can damage machinery or even cause fires and threaten the lives of your customers.
By adding carbon black, copper, or other conductive fillers to silicone, it can also become an electrically conductive material. By adjusting the type and content of conductive fillers, conductive silicone materials can achieve different conductive effects. Whether it is an antistatic grade silicone product or a highly conductive silicone that is used in EMI and RFI Shielding Components, it can meet your needs.
Read Silicone Rubber: Electrical Insulator or Conductive Material? to learn more about the conductivity of silicone materials.
Easy to Clean
For silicone cups used in bulk or for food and medical products where cleanliness is strict, using silicone materials is certainly a way to make cleaning easier.
First of all, most silicone materials have a non-stick surface. With the exception of those special-purpose silicone rubber sponges, the surface of most silicone materials can be smooth and dense, making it difficult for stains to remain on them.
Silicone materials are generally non-absorbent, and dirt will only be present on the surface, unlike bamboo, where the material draws outside chemicals to the interior, eventually leading to mold and odors. Even if dirt sticks to silicone material, because of prolonged use, a mild detergent, soapy water and a towel will be enough to take care of it.
Bacteria and mold also find it difficult to grow on them if they are properly cleaned and dried. This is why silicone sealants are often used in damp places like bathrooms.
Not only that, but many everyday silicone products support dishwasher-safe cleaning. With suitable use, you don’t need to worry about the dishwasher damaging them. Medical-grade silicone rubber can even be thoroughly sterilized using autoclaving, gamma irradiation, and many other methods.
Is Silicone Material Safe?
Certified food-grade and medical-grade silicone materials are safe when used correctly, but the safety of common silicones is not guaranteed.
Safety Standards and Regulations
Food-grade silicone materials need to pass the FDA’s food contact safety standards, and medical-grade silicone materials are not only subject to ISO 10993 and USP restrictions, but also to corresponding safety tests based on their use. These regulations and standards are the most direct guarantee of their safety.
Hypoallergenic
By themselves, silicone materials are biocompatible. Unlike latex, it is not prone to allergic reactions. Silicone allergy is rare and is usually caused not by the silicone but by other ingredients added to the material. Medical-grade silicone needs to pass a sensitization test, so it is much less likely to cause allergies.
Toxic Substances
Talc, PFAS, and other fillers or additives used to enhance performance may be present in silicone materials used for industrial manufacturing, but certified food-grade and medical-grade silicone materials don’t contain these strictly monitored hazardous substances. They also don’t have BPA, Phthalates or other toxic chemicals that can be released from the material and cause harm to the human body.
Vulcanization System
Food and medical-grade silicone materials are typically vulcanized using a platinum vulcanization system with safer vulcanizing agents and no harmful byproducts, which further enhances their safety.
Stability
They are very stable and hardly react with food or tissues in the human body, even at higher baking temperatures. As long as they are used correctly and within the labeled temperature tolerance range, you and your customers can enjoy the convenience of high-quality silicone materials with confidence.
Here is more information about the safety of silicone materials and how to choose safe silicone materials: Is Silicone Toxic: Silicone Safety Guide.
Types of Silicone Material
High-temperature Vulcanized Silicone Rubber(HTV/HCR)
High-temperature vulcanized silicone rubber is also called HCR silicone, because it is a very viscous liquid when it is a raw material. It is sold in the form of blocks or sheets and needs to be cured at high temperatures. The physical and mechanical properties of this silicone material are better, and it is suitable for making conveyor belts and gaskets. However, it is more difficult to make fine parts with HCR.
Room-temperature Vulcanized Silicone Rubber(RTV)
RTV Silicone is a type of silicone material that can be easily cured at room temperature. It is widely used in life because it is easy to use. For example, the glass adhesive you normally see is made using RTV, and it can also be used to make molds or for 3D printing.
Liquid Silicone Rubber(LSR)
Liquid silicone rubber is a silicone material that is a low-viscosity liquid before processing. It has good flow properties, so it is possible to replicate many of the details of the product in the mold, creating very fine parts. Some shapes that are difficult for other silicone rubbers to process, such as films and barbs, can also be mass-produced with LSR.
It is also highly transparent, so it can be used to produce lamps or optical components. LSR is well known for its use in food production and medical applications. Food-grade liquid silicone rubber and medical-grade liquid silicone rubber are highly pure, safe, and biocompatible.
Click A Simple Guide to Silicone Rubber Types and Applications to learn more about different types.
Applications of Silicone Materials
Industrial Manufacturing
Silicone materials are common in industrial manufacturing. Silicone O-rings and gaskets can be friendly with a wide range of industrial raw materials to provide a long-term, stable seal. Mixing two-component silicones can also be used to create delicate molds that can accept a variety of contents. Flexible silicone can provide acoustic, cushioning, and thermal insulation, so it is often used as a cushioning material.
Construction and Decoration
In the construction industry, silicone materials are often found in the form of coatings and sealants. Silicone-based paints and coatings have a bright, uniform color and are not prone to fading after long periods of use. Silicone-based paints and coatings adhere strongly to a wide range of materials, and are useful on metal and glass where acrylic paints don’t perform well.
Silicone sealants have good water resistance and are more resistant to UV as well as temperature changes, so they can help you achieve a reliable seal even in damp interiors, waterlogged fish tanks or variable outdoor environments.
Automotive and Aerospace
In the automotive and aerospace fields, silicone is a sealing material that can remain elastic at both high and low temperatures. For automobiles that use electricity as a power source, silicone foam gaskets not only provide reliable electrical insulation but can also be used as a highly elastic, flame-retardant material.
Silicone can also be made into a silicone hose that is more durable than traditional rubber hoses. It is compatible with a wide range of coolants and can tolerate the high temperatures generated by the operation of high-performance vehicles.
Electronics and Appliances
Because of their ability to block electrical currents, silicone materials are used in electronic component housings, wire insulation, and potting compounds. Silicone rubber with thermally conductive fillers not only prevents power from escaping, but also helps dissipate heat. Food-grade silicone materials that are safe enough to be used in microwave ovens and refrigerators are also used in sealing strips to provide double protection for the safety of your customers.
Food Processing
Silicone materials are your reliable partner for food processing. Whether it’s silicone baking mats and cupcake molds for baking, silicone ice trays for year-round cold temperatures, or silicone conveyor belts used in food processing and high-temperature conveying applications, silicone products are non-toxic, odorless, and safe within the recommended temperature range.
If you’re looking for a baking glove material that is insulating and safe, silicone is a good choice. Silicone fresh-keeping bags are lightweight, durable, easy to clean, and are ideal for storing vegetables because they are breathable.
Medical Field
Flexible and biocompatible silicone materials are a hot topic in the medical field. For chest drains that need to be in the body for a long period of time, silicone is the material of choice.
Silicone handles made using the overmolding process save costs and prevent surgical instruments from slipping during use. Precisely sized and shaped silicone parts in medical devices greatly enhance precision and improve medical efficiency.
Daily Consumer Products
Even for babies, silicone baby pacifiers are safe enough. In addition, you must be no stranger to silicone cell phone cases and silicone powder puffs, which don’t easily adhered by dirt and can be used for a long time without yellowing. Soft silicone watch bands are more comfortable to wear and can withstand outdoor UV.
Silicone Material vs. Rubber Material vs. Plastic Material
| Characteristic | Silicone | Rubber | Plastic |
| Cost | expensive | cheap | cheap |
| Lifespan | 8-30 years | 3-10 years | 2-20 years |
| Hardness
| 25-80 Shore A | 30-80 Shore A | 60-90 Shore D, much harder |
| Temperature tolerance range | -60°C-230°C | -40°C-125°C | -20°C-100°C (Special plastics such as Teflon are higher) |
| Chemical compatibility | good but not fuel-resistant | resistant to fuel oil but not solvents | poor (Teflon: excellent) |
| Mechanical strength | flexible but not wear-resistant | high elasticity, abrasion resistant, tear resistant | high tensile strength, high hardness |
| Weather resistance | excellent | poor | poor |
| Safety | excellent | prone to allergies, contains harmful additives | may contain BPA and plasticizers safer: PP/PE |
A more detailed comparison is also available here: Difference Between Silicone and Rubber.
FAQ
Is Silicone Material Environmentally Friendly?
Silicone materials are environmentally friendly compared to materials such as plastic and rubber. Silicone is non-toxic, and the chemicals produced when it is incinerated are also non-toxic. Although it takes a lot of energy to manufacture silicone materials, the durability of silicone makes up for it. In addition, silicone can be recycled by specialized recycling chains, but it is not yet widespread.
Silicone Sustainability: Is Silicone Recyclable?
Will Silicone Melt at High Temperatures?
No. Silicone material will deteriorate and lose its properties when it exceeds the range it can withstand, but it will not really melt into a liquid like plastic. At high temperatures, the internal structure of the silicone material is destroyed. Its surface will yellow or even turn black, and its original pliability disappears, and it becomes fragile.
Final Thoughts
Silicone is a high-performance material with a wide range of applications. Its properties of weather resistance, high and low temperature resistance, safety and flexibility allow it to be made into many products, and the quality of the products is closely related to the quality of the silicone.
As a silicone product manufacturer with more than 20 years of experience, Legensilico specializes in liquid silicone injection molding, compression molding, and many other silicone processing and production techniques, as well as providing custom silicone services. If you want to know more, please click on us!
