10 Misconceptions About Liquid Silicone Rubber

10 Misconceptions About Liquid Silicone Rubber

The family of silicones includes a vast array of compounds, making it the most widely used group of materials worldwide. Liquid silicone rubber (LSR) is extensively utilized in consumer goods such as home appliances, faucets, electronics, baby items, food and beverage products, and healthcare applications. It also has considerable applications in industries like automotive, aviation, industrial and construction, textiles, toys, and recreational products.

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Many myths and misconceptions about silicone materials, especially Liquid Silicone Rubber, can hinder industry professionals from fully utilizing these materials. Below are some of the prevalent myths about the silicone family, along with explanations of why they are inaccurate.

1. Silicone Is a Chemical Element or Ingredient

Silicones represent a collection of chemicals that can exist in different forms such as liquids, gels, and solids. It's important to note that silicone is not a standalone chemical element; instead, it is a nonmetal in the carbon family found in group 14 on the periodic table. Liquid silicone rubber consists of two components that reinforce long polysiloxane chains aided by specially treated silica. The first component may include a platinum catalyst that cross-links with a second component, which is a methyl hydrogen siloxane combined with an alcohol inhibitor. Silicone rubbers are constructed from long macromolecules formed by silicon (Si) and oxygen (O), and their properties can vary based on their arrangement, enabling diverse applications.

2. Silicone Rubbers Are Synthetic Materials

While it's true that silicone rubbers, including LSRs, are synthesized through human intervention that modifies naturally occurring silicon, the base material is completely natural. Silica, or sand, consists of silicon and oxygen. Historically, humans have utilized natural silicon materials in the creation of arrowheads and bowls. Silicone arises from silica’s transformation and processing, connecting it to natural elements.

3. Silicone Rubbers Can Only Be Processed and Applied at High Temperatures

Various silicone types, like Room Temperature Vulcanization (RTV) silicone rubbers, can be processed and applied at ambient temperatures. If an application requires LSR, it can be adjusted to allow for molding and vulcanization at lower temperatures, primarily for use in electrical and electronic sectors. This exceptional elastomer not only exhibits good low-temperature flexibility but also boasts remarkable high-temperature resistance. The three primary types of silicone rubber include:

• High-temperature vulcanized (HTV): A solid silicone rubber that requires temperatures similar to traditional rubbers for vulcanization, offering high temperature and chemical resistance.
• LSR: Injected into molds using specialized equipment, LSR is key in fabricating components for a variety of industries.
• Room temperature vulcanized (RTV): This silicone rubber cures at room temperature, providing a soft to medium hardness, making it ideal for automotive, electronics, and aerospace applications.

4. Silicone Rubbers Are Tacky

This misconception is linked to the tactile experience of silicone rubber. While many believe all silicone rubber is sticky, this varies depending on processing and application requirements. For certain uses, such as cable insulation or medical applications of LSR, the surface of the part must be smooth without any tackiness. Modifications can be made using additives like Mica or adjusting processing conditions to achieve the desired finish.

5. Silicone Rubbers Are Soft and Flexible

Silicone hardness is measured using the shore scleroscope; typical rubber bands score around 25 Shore while skate wheels may reach 100 Shore. The hardness scale varies from 0 to 100 Shore A, from gel-like materials to firm substances. There's a common misconception that all silicones possess a hardness of less than 40 Shore, which inaccurately suggests they have low mechanical properties. In reality, there are numerous ways to enhance silicone rubber hardness, including crosslinking and adding fillers. Notably, optical liquid silicone rubber showcases a hardness of 70 Shore with minimal elasticity. Moreover, silicone rubbers exhibit a tensile strength of psi, contributing to their durability and flexibility across varying temperature ranges, vital for challenging applications.

6. Silicone Rubbers Generate a Lot of Fumes When They Burn

Some individuals worry that burning silicone rubber releases harmful fumes, potentially impacting specific applications. However, depending on the type of silicone, certain types—particularly platinum-cured silicone rubber—do not emit significant gases during processing, while peroxide-cured types may require proper ventilation. Silicone rubbers are naturally self-extinguishing, and gas generation can be minimized by incorporating flame retardants and following industry standards.

7. Silicone Rubbers Contribute to Atmospheric Contamination

Environmental pollutants typically include volatile organic compounds (VOCs), such as acetones and alcohols, which are absent in silicone rubber and more common in plastic materials. Chlorofluorocarbons (CFCs) can harm the ozone layer. Due to their inorganic nature, silicone compounds do not contain these detrimental chemicals, making them less impactful on the environment. The LSR molding process is notably efficient, yielding minimal waste.

8. Silicone Rubbers Take Thousands of Years to Degrade

Under appropriate environmental conditions, the silicon-oxygen backbone of LSR can decompose into water, silicate acid, and carbon dioxide. Elements like sunlight and atmospheric oxygen encourage the breakdown into lower molecular-weight silicone chains or Cyclopentasiloxane. When buried, soil minerals act as catalysts, expediting degradation in just a few days. LSR components are recyclable, and with minimal waste during production, they present a remarkable eco-friendly profile.

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9. Silicone Rubbers Create Allergies and Irritations

This topic is well-researched, and unlike rubbers derived from natural latex, silicone rubbers do not generally irritate the skin or cause allergic reactions. Silicone-related allergies often arise from contaminants present during the manufacturing of silicone-containing products. The innate biological inertness characteristic of silicone, including Liquid Silicone Rubber, makes it biocompatible and hypoallergenic, presenting a safe alternative for individuals with latex allergies.

10. Silicone Rubbers Bioaccumulate in the Human Body

Bioaccumulation refers to a toxic substance's buildup in the tissues of a living organism. This happens when the intake of a substance surpasses its rate of expulsion or metabolic breakdown. Silicone rubbers demonstrate compatibility with body fluids and human tissues, leading to minimal tissue response in implants when compared with other elastomers. Although Liquid silicone rubber may pass through the body if injected or ingested, there are no applications intended for injectable forms. Compliance with FDA, ISO, and Tripartite biocompatibility guidelines for medical products is mandatory. Silicones do not support bacterial growth, offer stain and corrosion resistance, and are easy to clean.

Bonus Misconception: Silicone Rubbers Cause Disease

Given that several silicone rubber uses involve direct contact with the human body or food, there are concerns about potential health risks. However, the molecules released during use are too large to penetrate bodily tissues. The Food and Drug Administration (FDA) imposes strict standards on materials that come into contact with humans, sanctioning their use in food and beverage applications. Moreover, food-safe silicone is utilized extensively in cosmetics and pharmaceuticals.

Choose SIMTEC for LSR Components

LSR is tailored for a variety of applications and can integrate smoothly with different materials and processes. It also boasts one of the most efficient tooling processes for high-volume production, facilitated by rapid cycle times. Silicone rubber presents numerous optimization avenues, ensuring efficiency in manufacturing parts essential for your operations.

With over two decades of experience in working with LSRs, SIMTEC offers advanced automation and technology, alongside a knowledgeable team specializing in LSR and liquid injection molding (LIM). Our commitment is to supply consistent, high-quality LSR components, accommodating simple to complex design specifications across diverse industries. We are ISO, ISO, and IATF certified, guaranteeing that your products meet the rigorous quality standards demanded in manufacturing. Reach out to us today for more information on optimizing your products with LSR materials.

Liquid Silicone Rubber(LSR): Properties, Molding, and ...

Liquid silicone rubber is favored by manufacturers for its outstanding properties that suit demanding applications.

Tasteless and Odorless

This material is particularly suitable for food and beverage, as well as baby products, due to its lack of taste or odor, allowing it to meet stringent FDA standards.

Biocompatibility

Compared to other elastomers, liquid silicone rubber has superior bacterial resistance and does not corrode or stain materials. It showcases significant compatibility with bodily fluids and human tissues, making it ideal for skin-contact items since it is hypoallergenic.

Chemical Resistance

Liquid silicone rubber materials can endure oxidation, water, and various chemical solutions such as acids and alkalis. They are suitable for sterilization processes, including e-beam, ethylene oxide (ETO), and steam autoclaving, along with several compatible methods for medical and healthcare applications.

Transparency and Pigmentation

Liquid silicone rubber is naturally translucent. Its inherent white color is also compatible with pigmentation, allowing for custom-colored molded products.

Electrical Properties

Components made from liquid silicone rubber offer excellent insulating properties that adapt well to electrical applications, functioning efficiently across a wide range of temperatures better than traditional insulating materials.

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