Silicone has quickly become the extremely popular safe alternative to toxic plastics due to its excellent characteristics such as high & low-temperature resistance, low chemical reactivity, water repel, resistance to UV, etc. It is consistently marketed as inert and versatile, thus silicones have many uses in a variety of industries and consumer products, silicone cookware is one of the most popular applications, silicone bake mold, silicone ice tray, silicone fermentation lids, etc.

1. What is silicone?

So, what is silicone? where does silicone come from? To answer these questions, let’s figure out some terminologies relate to silicone first.

  • Silicon
    Silicone vs silicon, many take the two as one thing, because they are almost spelled the same and sound similar. But, in fact, they are two very different things, silicone should not be confused with silicon. Silicon(Si) is the fourteenth element on the periodic table, which is a metalloid, meaning it has the properties of both metal and nonmetal, and it is the second most abundant element in the earth’s crust, following oxygen. Silicon is most commonly combined with oxygen in the form of silicon dioxide or silica, it doesn’t occur in its pure form in nature.
  • Silica
    Silica, also known as silicon dioxide, is reduced to produce silicon metal, which is reacted with other compounds to produce silicones.  Found in nature as quartz, silica, or silicon dioxide is the most common component of beach sand, that’s why we say silicones are made of sands.
  • Silicone
    Silicone also known as siloxanes, is a man-made polymer made up of silicon, oxygen, carbon, and hydrogen. Silicones are produced in forms including silicone fluids, resins, and liquid or flexible rubber-like solid silicone.

In short, silicone is a synthetic substance made up of silicon, well, silicon is an element extracted from silica.

silica silicon silicone

2. How is silicone made?

Silica is put into a silicon furnace at a high temperature to drive the oxygen out of silica, the reaction between silica and carbon produces silicon. The powdered silicon was then combined with methyl chloride and heated once again, forming methysilane, phenylsiane, vinylsilane, and fluoroalkylsilane, which after further reaction and refinement, made the silicones including fluids, rubbers, liquid rubbers, resins, and silanes.

3. Is silicone environmentally friendly?

Is silicone safe or toxic? is silicone environmentally friendly? these are frequently asked questions, as we are paying more attention to safety and nature. The answer lies in the safety of silicone compounds: siloxanes D4 and D5.

The European Chemicals Agency 2016 stated that:

D4 is a persistent, bioaccumulative and toxic (PBT) substance and D5 is a very persistent, very bioaccumulative (vPvB) substance .

But the silicone industry, independent scientific panels, and government authorities in several world regions initiated environmental monitoring program in 2016, had produced a robust data demonstrating that:

Siloxanes pose little or no risk to the environment
No regulatory restrictions are warranted

In 2017, members of  SEHSC (Silicones Environmental, Health, and Safety Center ) submitted the final result of the D4 environmental monitoring program to EPA( the U.S. Environmental Protection Agency ) and concluded that: D4 does not harm the environment.

4. Is silicone recyclable?

Wasted silicone products can be recycled and processed back into silicone oil used as lubricants, thermic fluid oil, or hydraulic fluids.

5. Is silicone biodegradable?

Besides the siloxanes D4 & D5 which are very persistent, other silicones can be biodegraded readily in the environment. Though D4 / D5 is almost complete inertness, they are no harm to our environment.

P.S. In another text: Is silicone safe? we had discussed the safety of silicone to humans.