The term Silicone in material sourcing is a linguistic minefield and presents great confusion for many people. Searching for silicone using the Internet can yield results such as shoe box packets that absorb moisture, as well as high-heat gaskets used on EVs.
These two products are not the same thing. Contributing to this confusion is the use of terminology translation in the manufacturing sector, specifically in the Chinese language, where the word Guijiao can refer, in a very broad sense, to both materials.
In fact, in professional English and chemistry, Silicone Rubber and Inorganic Silica Gel are two very different materials with very different uses. This should serve to clarify and help consumers to understand the differences between Organic Silicone Rubber and Inorganic Silica Gel.
The Terminology Trap: Clearing the Air
First, let’s clear up some of the confusion around the names associated with cross-border procurement before you start using chemistry.
1. Inorganic Silica Gel - (Also Known as “Absorber”
Silica Gel is what chemists and those who package products are referring to when they say “Silica Gel” – hard porous granules that are used for drying things out.
Chemical Composition – Inorganic
Common Form – Clear beads or white powder
2. Silicone Rubber - (Also Known as “Elastomer”)
Silicone is a polymer used to produce various parts in engineering and design. Silicone is organic, meaning it contains carbon atoms and derives its composition from silicon, but predominantly it is an organo-silicon hybrid.
Silicone can take on many different forms, such as sheets, tubes, liquids and molded parts.
Note: If you are visiting Hong Kong or Taiwan, you may hear the word Xi-li-kang, which is a Chinese word that phonetically translates to the English word “silicone” and refers specifically to silicone as a rubbery material; it does not refer to the desiccant that absorbs moisture from the air.
The Technical Showdown: Inorganic vs. Organic
Choosing suitable materials requires an understanding of the differences between inorganic silicate gel and silicone rubber (polysilicone) in terms of chemical composition.
1. Chemical Composition
Inorganic Silicate Gel: This product is a very active adsorptive material, and it consists of amorphous silicon dioxide. The production is accomplished by the reaction of sodium silicate with sulphuric acid and then aging and bathing in acid. The "magic" of the product is its unique structure, which contains a large number of nanometer-sized pores designed to trap moisture.
Polysilicone or Silicone Rubber: This product is a Polymer having a high molecular weight in combination with a chemical structure that has alternate Silicon and Oxygen atoms for its back-bone; in addition, the Silicon atoms within the polymer contain Organic Groups, which may include methyl, vinyl and phenyl.
Modification: The addition of phenyl groups creates Low Temperature Resistance (-110°C); and the addition of trifluoropropyl groups creates Fuel/Oil Resistance (Fluorosilicone).
2. Physical Properties Comparison
| Fonctionnalité | Inorganic Silica Gel | Silicone Rubber (Organic) |
| State | Hard granules, beads, or irregular rocks | Soft elastomer, liquid, or gel |
| Tactile Feel | Hard, brittle (like glass or rock) | Soft, rubbery, stretchable, flexible |
| Primary Function | Adsorption (Traps water/gas) | Sealing, Insulation, Flexibility |
| Stabilité thermique | Heat resistant, but loses function (desorption) at high heat | Excellent. Operates from -55°C to 250°C |
| Reactivity | Inert (reacts only with strong alkali/HF) | Inert, biocompatible, high oxygen permeability |
Applications: One "Drinks," The Other "Seals"
Because their properties are opposite, their applications rarely overlap.
1. Applications of Inorganic Silica Gel
Leveraging its microporous structure:
Desiccants: Moisture control packets in electronics, leather goods, and food packaging.
Purification: Chromatography silica used in labs for purifying pharmaceuticals and separating DNA.
Carriers: Used as a substrate for industrial catalysts.
Stabilizers: Used in beer and beverage filtration.
2. Applications of Silicone Rubber
Leveraging its elasticity and weatherability:
Electronics: Waterproof gaskets, conductive keypads, and potting gels for PCBs.
Power & Energy: High-voltage insulators and cold-shrink cable accessories (replacing ceramics).
Medical & Consumer: Baby nipples, medical-grade tubing, and respiratory masks (Biocompatible, FDA/USP Class VI compliant).
Automotive: Engine gaskets, hoses, and spark plug boots (Oil and heat resistance).
Conclusion
Let's get down to business and forget the big words.When you mix these 2 substances, it's like mixing up a sponge with a wetsuit. They are both concerned with water, but they work with it in very different ways.
To help you avoid making a huge mistake in sourcing something, here is a quick checklist:"SQUISH"TEST If it is stiff and hard with sharp edges, that's Silica Gel — a product to keep things dry.
If it is flexible and stretchy and regains its shape, then that is Silicone Rubber — a product used for constructing parts.
SUPPLIERCHECK
If a supplier uses the phrase "Xi-li-kang" or "Organic Silicon," you know that you're getting Silicone Rubber for molding.
So remember, Silica Gel is used to absorb moisture and Silicone Rubber is used to keep it out.
Techniquement, il s'agit d'un caoutchouc synthétique (élastomère). Bien que les plastiques et les silicones soient tous deux des polymères, leur chaîne principale diffère. Les plastiques (comme le PE ou le PP) sont à base de carbone et dérivés du pétrole brut. Le caoutchouc de silicone possède une chaîne principale silicium-oxygène (issu du sable de quartz), ce qui lui confère des propriétés uniques, plus proches de celles de la roche (résistance à la chaleur) que de celles du plastique.
R : C'est là toute la confusion autour du #1 dans le secteur.
Silicium (sans ' e ') : Élément chimique naturel (Si) présent dans le sable et les roches. C'est un métal dur et cassant utilisé pour fabriquer des puces informatiques.
Silicone (avec un ' e ') : Un matériau souple synthétique dérivé du silicium. Qu'il soit souple, extensible ou liquide, c'est Silicone.
C'est un synthétique semi-organique Ce matériau occupe une place à part. Il n'est pas " naturel " comme le latex (issu de l'hévéa), mais il ne s'agit pas non plus d'un synthétique purement dérivé du pétrole comme le PVC. Son origine minérale (le sable) le rend chimiquement plus stable que les caoutchoucs organiques.
Non. Contrairement aux thermoplastiques, le silicone est un matériau thermodurcissable. Une fois durci, il ne fondra pas et ne redeviendra pas liquide. Il conserve sa forme jusqu’à 250 °C (482 °F). S'il est exposé à une chaleur extrême (supérieure à 400 °C), il finira par devenir cassant et se décomposera en poudre de silice, mais il ne fondra jamais.
On peut affirmer qu'il s'agit du caoutchouc le plus résistant aux intempéries qui soit. Sa liaison moléculaire (Si-O) étant similaire à celle du quartz, il est pratiquement insensible à Rayonnement UV, ozone et pluie. Alors que les pneus en caoutchouc naturel se fissurent au bout de quelques années, les isolateurs en silicone des lignes électriques peuvent durer 20 à 30 ans à la lumière directe du soleil sans se détériorer.
Il s'agit de la même composition chimique, mais sous des formes différentes :
HCR (caoutchouc à haute consistance) / HTV : Se présente sous forme de blocs compacts (comme de l'argile). Idéal pour le moulage par compression, l'extrusion (tubes) et la fabrication de pièces à moindre coût.
LSR (caoutchouc de silicone liquide) : Livré dans deux bidons de produit liquide (A + B). Idéal pour le moulage par injection de haute précision, la production en série automatisée et les pièces de qualité optique.
Non. Contrairement aux bouteilles d'eau, il ne se décompose pas en microplastiques, mais il n'est pas non plus compostable. Il restera dans une décharge pendant des décennies sans libérer de substances chimiques.
Yes, but not in your curbside bin. It requires a specialized recycling facility. Cured silicone can be ground down into crumbs (for playground mats) or chemically depolymerized back into silicone oil (a process currently being scaled up by major manufacturers like Dow and Wacker).