You can cure silicone in various ways. And the method you choose depends on what you want to get out of your end product. Two of the most widely used curing methods are platinum curing and peroxide curing.
So what exactly is the difference between these two curing methods? What are their strengths and weaknesses? Which one is better for your application? Read on to learn about all of these and more.
1. What is Silicone Curing? How Does It Work?
Many silicone products used in various industrial functions need to be in a solid state. As you know, uncured silicone takes the form of a highly-adhesive, viscous gel. You need a way to convert it into a solid material. That’s where silicone curing comes in.
During the curing process, the synthetic silicone is chemically cross-linked via a curing agent. Two of the most widely used curing agents are peroxide and platinum.
These two reagents differ in terms of chemical properties. And the properties you get for your end product depend on which curing agent you apply.
2. What’s The Difference Between Peroxide and Platinum-Cured Silicone Rubber?
Peroxide-cured silicone products are considered conventional. But platinum-cured silicone has been increasing in popularity. Let’s go in depth into these two resulting products to see how they differ.
2.1 Platinum-Cured Silicone Rubber
This curing method is also known as the addition system. That’s because it undergoes an addition reaction to produce the desired polymer.
Platinum acts as the catalyst, producing a reaction from the raw siloxane polymer. This reaction creates an ethyl bridge between the platinum catalyst and the polymer. In other words, it creates a cross-link in the polymer chain.
In contrast to peroxide curing, platinum curing has zero byproducts. It also has a faster curing time.
- Platinum-cured silicone rubber is widely considered the “cleaner” choice. Unlike peroxide curing, which produces volatile acids, platinum curing results in no byproducts. This makes platinum-cured silicone preferred for food and medical applications.
- It has better visual clarity and transparency. These qualities make it suitable for when see-through visibility is a requirement.
- Platinum-cured silicone is superior in a number of desirable properties. These properties include higher levels of tensile strength, elongation, and tear strength.
- Platinum curing does not require the use of talc – a mineral that’s been linked to health issues.
- Platinum-curing is more expensive to perform. And the cost of its raw materials are also on the higher side. It may not be ideal if you’re concerned with high production costs.
- These variants tend to have a shorter shelf life, resulting in higher quantities of discarded products.
- Platinum is more reactive to contamination. Exposure to substances like latex, sulfur, and tin-cure silicone will hamper its curing capabilities.
Applications for platinum-cured silicone rubber are extensive. You’ll see them applied in automotive products, clothing, and electronics, to name a few.
The most notable use of platinum grade silicone, however, are in food and medical-grade equipment. It’s simply favored when health and safety are primary concerns.
This is because of its inertness and its absence of contaminants that can impact safety. For this reason, it can easily comply with various safety standards.
2.2 Peroxide-Cured Silicone Rubber
Peroxide curing is the most widely-used silicone rubber curing method. You can also refer to it as vulcanization. Polymer chain cross-linking occurs by breaking down peroxide at high temperatures.
Unlike platinum curing, peroxide curing leaves behind byproducts. To reduce byproduct content, the silicone rubber must undergo post-curing treatment.
- Peroxide-cured silicone is cheaper to produce. It also has less-costly raw ingredients. You can produce more materials at a fraction of the price.
- It has a longer shelf-life compared to platinum-grade variants. You’ll be able to store it much longer, which means less waste and scrapped materials.
- Lesser heat tolerance translates to simpler processing. You can cure these silicone rubbers at lower temperatures.
- Processing requires talc to prevent the silicone from self-adhering.
- It’s less transparent and clear than a platinum-cured finish. These silicone rubbers are not ideal if your application requires material clarity.
- The curing process results in volatile byproducts. You have to employ post-curing to remove these impurities. For this reason, it’s not the first choice for medical and food-grade materials.
Peroxide-cured variants also see extensive use in many industrial and manufacturing applications. You’ll find peroxide-cured silicone rubbers in the automotive, aviation, and electronics sectors.
But for applications within the food, medical, and pharmaceutical spaces, peroxide-cured silicone is not recommended. This is mainly because of its capacity for higher toxicity.
3. Platinum and Peroxide-Cured Silicone Rubber: Which is Better?
As you have learned, platinum and peroxide-cured silicone rubber both differ in processing. Each also has its own positives and negatives.
Generally, if your application must adhere to the highest health and safety standards, choosing platinum-cured silicone rubber is the way to go.
It also provides you with higher levels of tensile strength, tear strength, and elongation. Needless to say, these qualities are going to be useful for extreme conditions.
On the other hand, if budget is an issue, you might as well opt for peroxide-curing. It’s a cheaper and less complex process. Peroxide-cured products also have a longer shelf-life.
GX Silicone offers both platinum and peroxide-cured silicone variants. Our silicone rubbers undergo rigorous testing and quality assurance to make sure they meet industry standards and customer specifications.
For uses involving skin contact and food consumption, we recommend using platinum-cured silicone rubber, the ideal choice for these applications.
Both platinum-cured silicone rubber and peroxide-cured silicone have very stable characteristics and are widely used in our daily life. When purchasing silicone rubber raw materials, the most appropriate choice should be made according to your specific requirements.
If you need help in choosing a solution, just contact GX-SIlicone freely, our silicone rubber experts will give you helpful advice.