AO, AO … it’s home from work we go
In my December 29, 2010 post, the question was asked…
Q: How can Novinium achieve effective cable-life extension without a soak period? It would seem to me that Novinium puts less fluid into the cable than one would get with a soak period.
A: In my first post addressing this question I provided an abbreviated answer. We learned from the abbreviated answer that that when Novinium founders conceived of the first generation of treatment fluid over two decades ago we failed to check the relative diffusion rates of the phenylmethyldimethoxysilane (PMDMS) monomer and the condensation catalyst we had chosen to provide long life. This turned out to be a grave mistake, which we have corrected. In a subsequent post on January 3, 2011, Catalytic Considerations—Component I, I provided a more comprehensive answer, but I promised five new posts that would explain the functional improvement of the five kinds of ingredients in Cablecure 732 fluid.
In this third of five sub-posts we will explore the role of the antioxidants (AO). Every human knows the benefits of including anti-oxidants in their diets, consuming foods such as raspberries and blueberries. Besides their sweet taste, the antioxidants found in berries are single-shot deals. A single anti-oxidant molecule consumes a single oxidizer. What we need for cables is a molecule that quenches the nasty oxidizer and then regenerates itself—indefinitely. It would be nice for people too, but don’t hold your breath. For cables the folks at BASF® and Novinium have a solution.
The primary AO in Novinium’s Cablecure 732 fluid formulation is BASF’s Irgastab® Cable KV10. Furthermore all of the components of the Cablecure 732 UV package have antioxidant properties. These materials were described in To UV or not to UV. In the vernacular, these UV components are “two-fers” or “two-for-one” ingredients, because they fulfill at least two1 independent and important life-extension functions.
Antioxidants are included in virtually all modern cable compound formulations. Originally deployed by polymer compound manufacturers to prevent oxidation during cable extrusion, it has been shown by Matey and Labbe, in “Exploring the Water Treeing Inhibition Effect of Antioxidants for XLPE Insulation”, presented at Jicable ’07, the 7th International Conference on Insulated Power Cables (see pp 754-757), that antioxidants also slow the growth of water trees. It was further demonstrated be Sekii et al, in “Effects of Antioxidants on Electrical Tree Generation in XLPE”, presented at the 2001 IEEE 7th International Conference on Solid Dielectrics (see pp 460-464), that the presence of antioxidants increases the electrical tree inception voltage. KV10, the sulfur containing phenolic antioxidant utilized in Novinium Cablecure 732 formulation, has been demonstrated to slow the growth of water trees by a factor of four. The class of sulfur containing phenolic antioxidants has been shown to increase electrical tree initiation voltage by up to 75% at a concentration of just 0.2%w. KV10 enjoys a very high solubility in polyethylene and EPR, and because of its high molecular weight of 424.7, a very low diffusion rate. The combination of high solubility and low diffusivity yields a very low sweat-out or exudation flux as was shown by Matey and Labbe. AO can be found only in Cablecure 732 fluids, because it enjoys protection of U.S. patent 7,658,808, other pending patent applications, and their foreign equivalents.
1Ferrocene and Tinuvin® 123 are “three-fers.” Ferrocene is an antioxidant (AO), an ultra-violet absorber (UVA), and a voltage stabilizer. Tinuvin® 123 is an antioxidant (AO), a hindered amine light stabilizer (HALS), and a methanolic corrosion inhibitor.