The silicone family consists of a wide variety of compounds and is probably the most widely used family of materials in the world. Liquid silicone rubber materials are used in consumer products such as electrical and electronics, astronomy, biotechnology, and the automotive, aerospace, beverage, construction, paint, plumbing, textile and toy industries.
There are a number of myths and misconceptions about silicone materials as a whole, including liquid silicone rubber, that prevent some practitioners from using these materials with complete confidence. Below are the most common myths about the family of silicone materials, with a special focus on liquid silicone rubber, and a brief explanation of why each material is inaccurate.
misunderstanding #1: Silicone is a chemical element or ingredient
Silicone products that come to mind first are often breast implants, lubricants, an ingredient in some cosmetic products, and may even be confused with silicone. The reality is that silicones are a family of chemicals with different states (liquid, gel, solid). Specifically, silicone rubbers, which are long molecules formed from silicon (Si) and oxygen (O), can have different properties and be used in different applications depending on how they are arranged.
Misunderstanding 2: Silicone rubber is a synthetic material
Silicone rubber, including liquid silicone rubber, is synthetic in the sense that it was created by humans. However, the raw material is completely natural: sand or "silica" is formed from silicon and oxygen. In fact, humans have been using natural silicon materials in arrows and bowls for years. Although silicon, silica, and silica are different, the confusion is understandable. To clarify: silicon is a chemical element; silica is a type of silicon dioxide (sand) used to produce the silicone family of materials.
Misunderstanding 3: Silicone rubber can only be processed and applied at high temperatures
There are different types of silicones, such as room temperature vulcanized (RTV) silicone rubbers that can be processed and applied at room temperature. If the application requires the use of liquid silicone rubber (LSR), it can be modified so that it can be molded and cured at low temperatures. This is mainly used for electrical and electronic applications and the making of silicone molds.
Misunderstanding 4: Silicone rubber is very sticky
This myth has to do with the feel of silicone rubber. Generally, people tend to think that all silicone rubbers are tacky, but this depends on processing and application requirements. For example, in cable insulation or medical applications using liquid silicone rubber, the surface of the part must be as smooth as possible without stickiness. Silicone rubber formulations can be modified to incorporate mica or to change processing conditions.
Misunderstanding 5: Silicone rubber is soft and elastic
Shore hardness is a scale used to measure the hardness of silicone, for example, rubber bands have a shore hardness of 25, while rollers or skates have a shore hardness of 100. All silicones are generally considered to have a hardness of less than 40 Shore, so they are considered to have low mechanical properties. However, this is not the case, there are many ways to increase the hardness of silicone rubber, such as creating more crosslinks or adding fillers. For example, optical liquid silicone rubber has a Shore hardness of 70 and is almost inflexible.
Misunderstanding 6: Silicone rubber produces a lot of smoke when it burns
It is believed that burning silicone rubber produces fumes and gases, which are detrimental for some applications. In fact, silicone rubber is inherently self-extinguishing. According to the combination of silicone rubber, adding flame retardants can completely eliminate the generation of gas and smoke and meet the standard requirements.
Misunderstanding 7: Silicone rubber will cause air pollution
The chemicals that cause environmental pollution are volatile organic compounds (VOCs) such as acetone, alcohols, methacrylates, acetates, etc. Chlorofluorocarbons (CFCs) have been identified as having an impact on the ozone layer. Due to their inorganic nature, organosilicon compounds or mixtures do not contain these contamination-causing chemicals.
Misunderstanding 8: Silicone rubber takes thousands of years to degrade
From the literal definition of biodegradation, silicone rubber is not biodegradable. However, under certain environmental conditions, the silicon-oxygen backbone can decompose into water, silicic acid, and carbon dioxide. Sunlight and atmospheric oxygen produce low molecular weight silicone chains (cyclopentasiloxane). When they are buried, soil minerals act as catalysts, accelerating chain scission and degrading silicone rubber in just a few days.
Misunderstanding 9: Silicone can cause allergies and irritation
Many studies have been done on this topic, and unlike other types of rubber (i.e. natural latex rubber), silicone rubber does not irritate the skin or cause allergic reactions. In fact, the inherent biological inertness of silicone (including liquid silicone rubber) is an advantage.
Misunderstanding 10: Silicone rubber bioaccumulates in the human body
Bioaccumulation is "the accumulation of toxic substances in the tissues of living organisms. This occurs when the rate of ingestion of a substance is greater than the rate of excretion or metabolic transformation of the substance". In extensive testing, compared to other elastomers, silicone rubber has excellent compatibility with human tissues and fluids, and minimal tissue response when implanted. Odorless and tasteless, silicone does not support bacterial growth and will not stain or corrode other materials. They are typically formulated to comply with FDA, ISO, and tripartite biocompatibility guidelines for medical products.
Misunderstanding 11: Silicone rubber can cause disease
Since many applications of silicone rubber come in contact with the human body or food, there are concerns that the material can cause disease. In terms of release of molecules during application, they are too large to penetrate tissue. The U.S. Food and Drug Administration (FDA) is very strict about materials that come into contact with humans and has been approved for use with consumables such as food and beverages, and food-safe silicones are also used in the cosmetic and pharmaceutical industries.