Introduction
In Silicone Rubber world ‘Platinum Cure Silicone’ and ‘Peroxide Cure Silicone’ are pretty common words. If you are new to silicone elastomer world, it may be create some confusion while selecting one as both are silicone grades with different curing mechanism and have their merits and demerits. In this blog post, we will try to provide a detailed comparison and address the common confusions. This will help you to make a better selection.
What is Curing?
In accordance with Wikipedia definition, ‘Silicone Curing’ is a fundamental chemical process used in polymer chemistry for cross-linking polymer chains. It is a crucial process of elastomer industry for hardening or solidifying un-cured synthetic or natural rubber material into a desired shape and size. Curing is normally done either by adding chemical additives (curing agent or hardener) or without chemical additives by using heat or UV system.
Silicone Rubber Curing
Since Silicone elastomer is also made out of a polymer chain, it also needs a similar kind of curing before making finished silicone rubber products. Silicone rubber, when not cured or solidified is a sticky, gummy and thick fluid. To harden it, it has to undergo cross linking and cure mechanism (hardening mechanism) which is done by a catalyst reaction i.e. cross link a liquid polymer system where it sets up and solidifies. Silicone is brought to an ideal shape and size mostly by a two-step process. This is done at the point of manufacture and then continued in an after cure process. The operative elements while curing vary synthetically to give the finished result with various properties. This process is irreversible.
For silicone rubber, there are two most commonly used curing systems. Platinum Cure System, and Peroxide Cure System.
Platinum-Cure System (Addition Cure system)
Platinum-cure technology has been accessible for quite a while, especially for applications which need high purity products like medical equipment, food & beverage processing industry, pharmaceutical application. In platinum cure silicone system two different chemical groups react in the presence of platinum. It is also called as “addition cure” or two-part system. The detailing is more complicated as compared to peroxide compounds. It necessitates that the base silicone polymer contains vinyl functional groups.
Dissimilar to the peroxide cure system, platinum is a genuine catalyst. It is not ingested through the process. Practically, in the platinum cure system, the activity has to be technically decreased as the platinum-catalyzed response happens even at normal temperature and pressure. This first request response happens considerably more rapidly than one started by peroxide, as it doesn’t confide in the rate-deciding step.
Peroxide-Cure System (Free Radical System)
Curing of silicone elastomer using peroxide has been a customary approach for a long time. Peroxide cure procedure is clear and straightforward which use free radicals for cross-linking generated by organic peroxides. There are basically two parts: different kind of peroxides and the silicone gum resin.
Although the term “catalyst,” is used while peroxide cure, it isn’t in a proper manner a true catalyst reaction as it gets absorbed during the process. A peroxide inducted method is categorized as a second order reaction. It generally has three steps.
At the point when the silicone elastomer is put in the heated process, the peroxide thermally deteriorates to make free radicals. These free radicals strike either a methyl or a vinyl group, depending upon the polymer and peroxide utilized thus forming active cross link sites. The active sites on the silicone polymer at that point join, framing a carbon-carbon bond.
| Peroxide Cure Silicone System | Platinum Cure Silicone System | |
|---|---|---|
| By Product | May produce by-product which is volatile in nature so it can be driven out by using high-temperature post curing | No by-products |
| Opacity | Final products are translucent & cloudier | Final products are more clear & transparent which offers better visual flow inspection of fluid |
| Purity | Pure & Clean | Consider purer and cleaner than peroxide cure |
| Physical Properties | Tensile strength, elongation and tear strength are good | Tensile strength, elongation and tear strength are comparatively better than peroxide cure |
| Mechanical Properties | Better | Good |
| Shelf Life | After mixing compound, it has a long shelf life | After mixing compound, it has a short shelf life |
| Processing | Easy to process, need lower temperature for curing | Hard to process, requires a high temperature for curing |
| Cost | Economical | Higher Cost |
Conclusion
To wind up, the two most broadly used silicone cure systems, i.e. peroxide cure system and platinum cure system, both offer safe, and durable silicone rubber parts. However, they differ in procedures, efficiency, qualities, results, and cost.
When high quality, crucial quantities, or recurrent purification is all-important, platinum cure system is the best choice. On the other hand, the peroxide cure system is a better choice for cost-effective, flexible, and undemanding products. It is normally, yet not all around, a more affordable option in contrast to platinum cured silicone, and regularly displays longer pump life in peristaltic-pump applications.
Accurate Rubber Corporation is experienced, reliable and customer-centric silicone rubber parts manufacturer which makes & offers silicone tubing, platinum cure tubing, food grade gasket, and other rubber parts as per your requirements. They possess the extensive experience to work with peroxide cure silicone as well as the platinum cure silicone systems and can guide you in your decision and all through your development to achieve the execution levels you require.