An introduction into Jehbco Silicones, where the company started, key employees and the company’s manufacturing capabilities.
Articles posted by Jehbco Silicones
Silicone Tubing for Peristaltic Pumps
Jehbco’s Silicone has a number of excellent properties, making it a good choice for many applications. Jehbco has many years of experience designing and manufacturing parts for a wide range of applications, from aircraft parts to food and medical tubing. One area where we have expertise is peristaltic pump tubing.
Peristaltic pumps are used in sensitive applications where fluid cannot be exposed to pump components. They are often used when the fluid must remain sterile (such as in medical applications), and when the fluid is very aggressive or corrosive. A peristaltic pump works by squeezing fluid through a flexible tube. The tubing must be able to withstand thousands of squeeze repetitions and also not react with or absorb the fluid being pumped. Jehbco’s medical grade silicone is an ideal material for peristaltic pump tubing.
Peristaltic pump
Jehbco manufactures medical grade tubing from pure silicone. Our silicone is inert and non-absorbent, making it suitable for most medical fluids, acids, bases and many other chemicals. Furthermore, our silicone tubing can withstand the repeated squeezing that occurs in peristaltic pumps with minimum fatigue. Jehbco’s tubing meets pharmaceutical industry standards and is ready to install in pharmaceutical pumping applications.
Peristaltic pumps are just one of the many applications of Jehbco’s high-quality silicone products. For help with the design of your own application, review our website at www.Jehbco.com.au and contact our sales team with any questions.
Image Credit & Thanks: Wikipedia
O-Ring Design with Jehbco: Sneak Peek
O-Rings are an extremely common and effective seal, consisting of a rubber ring with a circular profile, which is pressed into a rectangular groove or gland. Most applications can use a standard, off-the-shelf o-ring, but for those special applications that need a non-standard o-ring, here at Jehbco we can manufacture a custom o-ring perfect for the task.
Several standards exist for o-ring design, the most common being AS5857. These standards simplify design of o-ring seals, giving dimensions for both the rectangular gland and the o-ring itself. But some applications require a non-standard o-ring – very large seals, seals for existing non-standard glands and seals for non-rectangular glands, for example. When the seal is non-standard, the design is a nightmare – working out the gland size, the seal size, checking the seal squeeze and fit all require many design iterations and physical tests. Here at Jehbco, we’re working to simplify the design process with our in-house o-ring design software.
Figure-1 Testing our face seal designs with Jehbco Silicones
We are conducting physical tests of our automated o-ring designs, to ensure that the values our software gives work in the real world. Of course, new designs will still require physical testing, but we aim to reduce the number of test iterations required to produce the final design, and eliminate all the tedious hand calculations required for non-standard o-ring designs.
Figure-2 A sneak peek of our o-ring design software with Jehbco Silicones
Our software is still under development, but stay tuned for more news as we put our design software into service. For more information on our products and services, review our website www.jehbco.com.au and contact us with any questions.
Improving Extreme Temperature Degradation of Silicone Rubber Using Flame Retardant Additives
Silicone rubber is well known for its durability at high temperatures. While other polymers such as nitrile, polyacrylate, and polyurethane have maximum service temperatures of around 70-150oC, silicone can withstand operating environments around 200-250oC. However, exposure to extreme temperatures will cause the silicone to combust. A common way to improve the resistance to extreme temperatures and fire is to include flame retardant additives in the manufacturing process. Not only does this increase the ignition temperature of silicone, but it also increases the durability of silicone at high temperatures and changes the way it combusts. Jehbco’s flame retardant silicones have been tested under AS1530.3, EN45545 and other standards to guarantee your peace of mind for high-temperature applications.
Silicone rubber has exhibits unique behavior at elevated temperatures. While most plastics will begin to melt at high temperatures, silicone does not have a melting point and remains solid until combustion occurs. At high temperatures (200-450oC), silicone rubber will slowly lose its mechanical properties over time, becoming brittle. The exact autoignition temperature of silicone depends on many factors such as the hardness of silicone, curing catalyst and any additives used. The standard autoignition temperature is around 450oC.
Silicone also exhibits unique behaviour during the combustion process. As the autoignition temperature is reached, the sample will smoke briefly before it begins to crack and combust. The silicone will expand in volume as volatiles are released, before the brittle combusted silicone breaks away from the sample, and will disintegrate into a fine powder upon any application of pressure. Silicone rubber primarily consists of a silicon-oxygen-silicon backbone with various carbon-containing methyl and vinyl groups. Upon combustion, silicon dioxide and carbon oxides are produced. The carbon monoxide and dioxide gasses are released into the atmosphere, while the silicon dioxide, as shown in Figure 1, creates a layer of white powder on the surface of the sample. This layer of silicon dioxide cannot be combusted further and acts as an insulating layer to help slow down and prevent further combustion of silicone.
Figure 1: Insulating silicon dioxide powder forming on a combusted silicone rubber sample
At Jehbco, we have been researching and developing new silicone rubber for over 40 years. Our flame retardant silicones have had extraordinary success in improving the flame retardant properties of silicone rubber. As shown in Figure 2, two different levels of flame retardant silicone were combusted along with a standard silicone rubber sample. The flame retardant silicone both ignited at higher temperatures than silicone rubber, and the extent of damage in the samples after combustion is much lower than the standard silicone rubber.
Figure 2: Combustion of standard silicone rubber (left) compared to various flame retardant silicone (right)
Ultimately, if you are looking for a reliable construction material for high-temperature applications, Jehbco’s flame retardant silicones are among the most durable and reliable materials available on the market. For further information or advice about which flame retardant silicone best suits your application, please review the Jehbco website www.jehbco.com.au, and contact us with any questions.
Silicone vs Natural Rubber
At Jehbco, we manufacture our products exclusively from pure silicone. Silicone is a type of polymer known as an “elastomer” – these polymers are stretchy or elastic. For many applications, it is not quite clear which elastomer is the best to use. Probably the most well known elastomer is natural rubber, commonly known as latex. In this article, we’ll look at the properties of silicone and natural rubber and discover when you might choose one or the other.
Natural rubber, with the chemical name polyisopropene, is produced naturally from the sap of the rubber tree. Silicone, on the other hand, is a synthetic material. While both materials are elastomers, they differ in many of their properties. Some of these properties are summarised in the table below.
| Natural Rubber | Silicone |
| -50 °C to 80 °C | -50 °C to 230 °C |
| Excellent compression set | Excellent compression set |
| Poor weather resistance | Excellent weather resistance |
| Approx. tensile strength 25 MPa | Approx. tensile strength 5 MPa |
| Excellent abrasion resistance | Poor abrasion resistance |
| Not compatible with: ozone, strong acids, fats, oils, greases, hydrocarbons. | Not compatible with: hydrocarbon fuels, alkalis and acids, steam over 121 °C, trichloroethylene, aromatic hydrocarbons. |
| Compatible with: hot and cold water, weak acids, alcohols, ketones, aldehydes. | Compatible with: ozone, oils, brake fluids, hot and cold water, salt water, high molecular weight chlorinated hydrocarbons, fire resistant hydraulic fluid. |
Both natural rubber and silicone are able to operate at very low temperatures – down to -50 °C. However, silicone is able to operate at much higher temperatures than natural rubber. Natural rubber starts deteriorating at 80 °C and melts at 120 °C. Silicone is able to be formulated to operate up to 230 °C. Silicone also has significantly better flame resistance than natural rubber. For high temperature applications, silicone is certainly the better choice.
Neither silicone nor natural rubber have good resistance to hydrocarbon fuels and lubricants. However, silicone exhibits a wider chemical resistance than natural rubber, often making it the better choice for chemical sealing applications. The choice of material in chemical applications will depend however on the exact chemicals that the material will come into contact with. Both materials are used in applications such as piping and tank lining.
A discussion on Silicone Vs Rubber with Jehbco Silicone Specialists
Natural rubber exhibits much higher tensile strength, tear strength and abrasion resistance than silicone. It is used in high wear applications such as tyre treads and conveyor belts. Silicone has relatively low abrasion resistance, and in applications where a part will be subjected to abrasion and wear, natural rubber is a better choice.
Silicone has excellent resistance to weathering and UV, and is often found in outdoor applications such as door and window seals. In contrast, natural rubber weathers very quickly and is not suited to outdoor applications. If your application involves exposure to the elements, silicone is the better choice.
For help selecting a material for your application, please contact us with any questions.
Parylene-C Coatings on Silicone
In the silicone industry, a wide variety of coatings are implemented to enhance the physical properties of silicone products. There are many benefits of using chemical coatings, which include, but are not limited to: increased chemical resistance, decreased coefficient of friction, and decreased permeability to moisture.
Amongst the many types of chemical coatings available for silicone products, Parylene coatings are one of the most commonly used materials for silicone products in the food and medical sectors. Parylene is the colloquial name for a series of vapour-deposited coatings that provide chemical and moisture resistance to a range of different products. Parylene-C is the most popular type of Parylene coating used in the silicone industry, due to its ease of application, low cost, and the significant barrier properties it provides. Below is the chemical structure of a Parylene-C monomer, as well as its raw dimer form, known as diparaxylene.
Currently, Parylene-C coatings are used in the silicone industry to provide a low-friction, almost impervious barrier that can resist chemical attack and high electric currents. The inert, non-toxic properties of Parylene-C make it an ideal coating for silicone materials in the medical industry. Additionally, Parylene-C coatings are FDA approved, which make it an ideal coating for silicone products in the food industry. Furthermore, the high level of coating thickness control during the vapour deposition process can allow Parylene-C coated products to be used in high-precision instruments, such as seals in medical sterilisers.
Parylene-C is a thin conformal coating, meaning that it conforms to the topography of the material it is applied to. This is very beneficial for products such as oddly-shaped silicone extrusions, that may not be compatible with other forms of coatings. The ability of Parylene-C to conform to the topography of the given product is due to its unique vapour-deposition application process. Additionally, the vapour-deposition of the Parylene-C coating is normally conducted at room temperature, with no additional catalysts or solvents needed, which allows for the coating of thermo-sensitive or delicate products.
The application process of Parylene-C, while relatively simple, is an integral factor of the effectiveness of Parylene-C coatings. Raw, solid Parylene-C dimer is vapourised into a gas at 100-150°C and is split into individual Parylene-C monomers following exposure to temperatures >500°C. Under vacuum, the monomer gas is pulled into a deposition chamber, in which the desired product is coated at room temperature as the monomer gas polymerises into a solid, uniform coating. The product is removed to storage, and a cold trap at -100°C following the deposition chamber is used to remove residual Parylene-C.
At Jehbco, we strive to provide the perfect silicone product for your needs. For further information or advice about which silicone rubber and coating best suits your application, please review the Jehbco website www.jehbco.com.au, and contact us with any questions
Silicone Extrusions in the Rail Industry
Silicone is a versatile material with excellent properties. As such, silicone is a valuable material in many industries, and Jehbco manufactures silicone extrusions for a range of applications. One key application area is rail transport.
Trains are complicated pieces of machinery which are required to run frequently and reliably for many years of service. There are many parts of a train requiring an elastomer material and often these parts are subject to severe operating conditions. For example, door seals see repeated deformation and are exposed to the weather, while seals in engine compartments are subject to high temperatures and exposed to oil. For many of these parts, silicone is a natural choice.
Rail applications are safety critical, and all materials used in trains must conform to strict standards on fire safety. Historically, toxic smoke in train crashes has led to increased fatalities, and modern trains are constructed from materials that do not produce toxic smoke, so as to avoid this hazard. Jehbco’s silicone extrusions are able to meet national and international standards on flame resistance and smoke toxicity. This is a key reason for our silicone’s widespread use in train construction.
Silicone exhibits a range of other desirable properties. Silicone is flexible, strong, and extremely durable, being resistant to UV and ozone. This range of properties makes Jehbco’s silicone extrusions ideal for a number of internal and external applications, including door seals, window seals, HVAC gaskets and sealing of electronic enclosures.
Silicone is an elastomer, or flexible rubber. This means silicone is able to dampen vibrations and sound. Silicone sheeting is used in train walls and ceilings as sound insulation, and in other areas to dampen vibrations and increase passenger comfort.
Jehbco’s silicone can operate over an extremely large range of temperatures (from -50 °C to 230 °C), allowing it to be used for sealing applications near engines and other hot mechanical components. Silicone is unaffected by water, brake fluids and oils, making it a good choice for many applications requiring flexible tubing.
The properties of Jehbco’s silicone make it an ideal choice for many train parts. But is the shape and size of our product right for the application? Jehbco is able to custom engineer a silicone extrusion to any shape and size, and we work with our customers to design the perfect fitting part for any application.
For more details on Jehbco’s silicone extrusions and their applications, consult our website www.Jehbco.com.au and contact us with any questions.
Silicone vs Nitrile
When designing your next product, there are a myriad of elastomer materials to choose from. Jehbco manufactures all our products from 100% silicone. Is silicone the right elastomer for your application? In this article, we’ll explore the differences between silicone and a common competitor – nitrile – and clarify which material is the best choice for your design.
Acrylonitrile-butadiene, commonly known as nitrile or NBR, has excellent chemical resistance, similar to silicone. However, the two materials differ in many of other properties. The table below summarises some of their key differences.
| NBR | Silicone |
| -57 °C to 121 °C | -50 °C to 230 °C |
| Great compression set | Excellent compression set |
| Poor weather resistance | Excellent weather resistance |
| Approx. tensile strength 15 MPa | Approx. tensile strength 5 MPa |
| Good abrasion resistance | Poor abrasion resistance |
| Not compatible with: ozone, ketones, esters, aldehydes, chlorinated hydrocarbons, brake fluid, concentrated acids. Some formulations are not food grade. | Not compatible with: hydrocarbon fuels, alkalis and acids, steam over 121 °C, trichloroethylene, aromatic hydrocarbons. |
| Compatible with: hot and cold water, petroleum-based oils and fuels, silicone greases, hydraulic fluids, alcohols, weak acids and alkalis. | Compatible with: ozone, oils, brake fluids, hot and cold water, salt water, high molecular weight chlorinated hydrocarbons, fire resistant hydraulic fluid. |
Both silicone and nitrile exhibit excellent resistance to cold temperatures, remaining flexible down to -50 °C, with special formulations of nitrile remaining flexible to -57 °C (at the expense of other physical properties such as wear resistance). Nitrile can operate to 100 °C, or 121 °C with reduced longevity. Silicone can operate at much higher temperatures, up to 230 °C. This makes silicone the best choice for high temperature applications.
Both materials are resistant to a range of chemicals. Nitrile has excellent resistance to hydrocarbon fuels and oils, making it ideal for automotive fuel applications. Formulations of nitrile containing phthalate plasticizers cannot be used with food or children’s toys. Silicone, on the other hand, is food grade and is often used in food and water processing equipment. For any application, it is important to check that the elastomer is resistant to the chemicals it will come into contact with.
Nitrile has high tensile strength and excellent wear and abrasion resistance. By contrast, silicone has poor abrasion resistance, and for dynamic applications where elastomers must have good wear characteristics, nitrile is a better choice.
Nitrile exhibits poor resistance to weathering, UV and ozone, making it unsuitable for outdoor applications. Silicone has excellent weathering characteristics and is highly resistant to both ozone and UV. For outdoor applications, silicone is a clear winner.
While both materials exhibit good compression set, silicone generally undergoes less compression set than nitrile. This makes silicone a better choice in sealing applications where a long-lasting, reusable seal is required.
For help selecting a material for your application, please contact us with any questions.
Peroxide Curing in Silicone Manufacturing
An important part of the silicone manufacturing process is the kind of catalyst used to create the product. During production, a catalyst is added to make the silicone cure, which hardens and sets the final product. Typically, a peroxide catalyst is the cheapest and most common catalyst used to manufacture silicone gaskets, o-rings, strips and cords in the construction sector. The kind of catalyst used can have a significant impact on the product’s appearance, physical behaviour and chemical properties. Thus, it is important to understand how different catalysts can affect the properties of peroxide cured silicone. At Jehbco, we work with our clients to ensure that the ideal catalyst is used to deliver the best silicone product for your application.
Silicone Chemistry with Jehbco Silicones
By definition, a catalyst is a substance that facilitates a forward chemical reaction without being depleted as the reaction takes place. The first step in a peroxide cure is the spontaneous formation of peroxide radicals. These peroxide radicals then break double bonds in the silicone chain structure. The site where the double bond is broken is free to form a single bond with various chemical groups on another silicone chain through a variety of reaction pathways. The bonds that stretch between silicone chains forms a cross-link. This cross-linking between silicone chains is what causes an increase in toughness in the curing process.
Reaction Chain with Jehbco Silicones
Above: An example reaction to illustrate the formation of a cross-link between two separate silicone chains. The peroxide catalyst allows the double bond to be broken.
A side effect of peroxide curing is a phenomenon known as ‘blooming’. This occurs when the left-over catalyst migrates to the surface of the silicone, forming a powdery white substance or ‘bloom’. This bloom primarily consists of volatile organic acids. Due to this phenomenon, peroxide cured catalysts undergo a post-curing process where they are heated in a controlled and ventilated environment at 200OC for 4 hours. This process removes all of the catalyst and other extractables from the silicone, leaving behind a pure silicone rubber product. However, peroxide cured catalyst unsuitable for food grade applications, as any minuscule amount of extractables left in the silicone is undesirable due to contamination concerns.
The addition of around 1-1.5% w/w of peroxide catalyst to a silicone mixture is enough to facilitate cross-linking. The small amount of catalyst required, as well as the lower cost of peroxide catalyst, is what makes it useful and effective for silicone manufacturing. Peroxide cured silicones are typically more rigid than platinum cured silicones, making them an ideal material for construction or transportation applications. Peroxide cured silicones are often more opaque and sometimes darker than platinum cured silicone.
Ultimately, cross-linked, peroxide cured silicone is a strong, versatile material that is used to manufacture a variety of products. Deciding whether or not peroxide cured silicone is best for your application can depend on a number of factors, but it is most important to think about the cost of the product, product appearance and whether or not food grade silicone is required. At Jehbco we offer both peroxide and platinum cured silicones for an extensive range of applications and industries.
For further information or advice about which silicone rubber best suits your application, please review the Jehbco website www.jehbco.com.au, and contact us with any questions.
Talc and Silicone Extrusions
Jehbco manufactures custom silicone extrusions in our Sydney-based factory, carrying out all steps in-house, from product design and development to die cutting, material preparation and manufacture. This gives us fine grained control over the properties and quality of the final product, allowing us to tailor each product to the requirements of our varied customer base.
Jehbco’s manufacture of silicone extrusions is a process with several steps. The raw silicone material is first mixed and then fed to an extruder. The extrusion that comes from the extruder is passed through several stages of heating and then boxed or coiled. Finally, extrusions are placed in an oven for several hours to post-cure. The post-cure process reduces the stickiness of silicone, as well as removing volatiles and improving other properties.
In its raw form, silicone is quite sticky. While some applications require a high degree of stick and friction, such as gaskets which must be retained in joints without additional adhesive, many applications require lower friction than silicone naturally has. For example, o-rings must slide easily against machine parts and some seals must slide easily into a joint.
A problem with silicone’s natural stickiness is the tendency of some silicones to self-adhere when coiled. The coils of silicone extrusion may stick to each other, which can lead to tearing of thin sections during uncoiling. As extrusions are coiled prior to post-curing, the post-curing process does not solve the issue of self-adherence.
To reduce the stickiness of our extrusions, both for low friction applications and to eliminate the risk of self-adherence, we use a talcing process. After curing and before coiling, a thin layer of talc is applied to the surface of the extrusion. This layer of talc acts as a lubricant and prevents the extrusions from self-adhering when coiled. The talc does not react with the silicone and has no effect on the material properties of the extrusion; it only serves to reduce surface friction.
While the talcing process has previously been done by hand, Jehbco are currently implementing an automated talc application process. This will allow quicker application of a more even and consistent layer of talc on our extrusions.
Figure 1: An extrusion passing through Jehbco’s new talc applicator
On the other side of the coin, some applications require higher friction than our standard extrusions can offer. Not a problem! Jehbco can increase the coefficient of friction of our silicone in a number of ways: specifying softer (lower durometer) silicone, different grades of silicone and removing the post-cure process.
Jehbco makes every effort to ensure our product fits your application, from profile design to material properties.
For help matching our products with your application, please review our website www.Jehbco.com.au and contact us with any questions.