Arkema Sulfur Compounds Vultac: The Unsung Hero of Cable Insulation and Jacketing
When it comes to the world of cables—those quiet, coiled lifelines that power our homes, offices, and cities—most of us don’t give them a second thought. They sit in walls, under floors, and behind electronics, quietly doing their job without fanfare. But behind that unassuming exterior lies a complex world of materials science, engineering, and chemistry. One of the unsung heroes of this world is Arkema’s Vultac, a line of sulfur compounds that plays a crucial role in ensuring cables are not only functional but also safe, durable, and efficient.
In this article, we’ll take a deep dive into what makes Vultac such a standout in the realm of cable insulation and jacketing. We’ll explore its chemical makeup, its performance characteristics, and why it’s trusted by engineers and manufacturers around the globe. Along the way, we’ll sprinkle in some fun facts, analogies, and maybe even a joke or two—because even chemistry can be entertaining!
🧪 A Bit of Background: What Is Vultac?
Vultac is a product line developed by Arkema, a French multinational chemical company known for its innovation in materials science. Vultac specifically refers to a family of sulfur-based compounds used primarily as crosslinking agents in the production of rubber and polymer-based insulation and jacketing materials for cables.
Crosslinking? Let’s break that down.
Imagine you’re trying to hold a bunch of spaghetti noodles together. If they’re just lying there, they slip and slide around. But if you tie them together at multiple points, they form a stronger, more cohesive structure. That’s essentially what crosslinking does to polymers—it turns a bunch of individual polymer chains into a network, making the material tougher, more heat-resistant, and more durable.
Vultac helps achieve this crosslinking through sulfur bridges, which are chemical bonds formed between polymer chains. These sulfur bridges are especially effective in ethylene propylene diene monomer (EPDM) rubber, a popular material for cable insulation due to its excellent electrical properties and weather resistance.
🔌 Why Cables Need Good Insulation and Jacketing
Before we dive deeper into Vultac itself, let’s take a moment to understand why insulation and jacketing are so important in cables.
Insulation is the material that wraps around the conductor (usually copper or aluminum) and prevents the electricity from leaking out. It’s like the walls of a water pipe—without good walls, you get leaks, pressure loss, and potentially dangerous situations.
Jacketing, on the other hand, is the outer layer that protects the entire cable from the environment. It shields the cable from moisture, UV radiation, abrasion, chemicals, and mechanical damage. Think of it as the armor of the cable.
Both insulation and jacketing must meet a variety of performance criteria:
- Electrical insulation (low dielectric constant, high resistivity)
- Thermal stability (ability to withstand high temperatures without degrading)
- Mechanical strength (flexibility and resistance to wear)
- Chemical resistance (to oils, solvents, acids, etc.)
- Flame retardancy (especially in building and industrial applications)
And this is where Vultac shines.
⚙️ Vultac in Action: How It Works
Vultac works by facilitating sulfur vulcanization, a process that has been used for over a century to improve the properties of rubber. Vulcanization involves heating the rubber with sulfur, which forms crosslinks between the polymer chains.
In the context of cable manufacturing, Vultac is typically added during the compounding stage, where raw polymer is mixed with various additives to create the final material. The compound is then extruded around the conductor to form the insulation or jacket.
One of the key advantages of Vultac is its controlled reactivity. Unlike some crosslinking agents that can be too aggressive or unpredictable, Vultac offers a balanced curing profile, allowing for consistent and reliable processing.
📊 Vultac Product Overview
Let’s take a look at some of the main Vultac products used in cable applications and their key characteristics.
| Product Name | Chemical Type | Sulfur Content (%) | Cure Speed | Application Focus |
|---|---|---|---|---|
| Vultac 5 | Polysulfide | ~40 | Medium | EPDM, general-purpose |
| Vultac 7 | Polysulfide | ~35 | Fast | High-speed extrusion |
| Vultac 12 | Polysulfide | ~25 | Slow | Thick insulation, low smoke |
| Vultac 20S | Disulfide | ~18 | Very fast | Low-odor, fast curing |
| Vultac NS | Polysulfide | ~30 | Medium | Flame-retardant compounds |
| Vultac 7-HS | Polysulfide | ~35 | Fast | Heat-stable, low bloom |
🧪 Fun Fact: The "Vultac" name is a portmanteau of "vulcanization accelerator."
Each of these products is tailored for specific applications. For example, Vultac 12 is often used in low-smoke, halogen-free (LSHF) cable compounds because it produces fewer volatile byproducts during curing, which is essential for safety in case of fire.
🧬 The Chemistry Behind the Magic
At the heart of Vultac’s effectiveness is the sulfur atom. When heated, sulfur forms polysulfide bridges between polymer chains. These bridges are not only strong but also flexible, allowing the material to retain its elasticity while gaining toughness.
Let’s break down the vulcanization reaction in simple terms:
- Polymer chains (like those in EPDM) have double bonds that are reactive.
- When Vultac is added along with accelerators and activators (like zinc oxide and stearic acid), the sulfur becomes active.
- The sulfur forms crosslinks between the polymer chains, turning the material from a soft, sticky mess into a firm, elastic solid.
This reaction is usually carried out at temperatures between 140°C and 180°C, depending on the formulation and the desired cure speed.
The result? A cable material that can withstand extreme temperatures, resist degradation over time, and maintain its electrical properties even under stress.
🔋 Electrical Properties: The Silent Superpower
Cable insulation must have excellent electrical insulating properties. That means high dielectric strength, low dielectric loss, and high volume resistivity.
Thanks to Vultac’s contribution to the crosslinking network, EPDM compounds used in cables exhibit:
- Dielectric strength: 20–30 kV/mm
- Volume resistivity: >10¹⁴ Ω·cm
- Low dissipation factor: <0.005 at 1 kHz
These values place EPDM among the best-performing insulation materials, especially for medium- and high-voltage applications like power distribution and industrial cabling.
Here’s a quick comparison of common insulation materials:
| Material | Dielectric Strength (kV/mm) | Volume Resistivity (Ω·cm) | Temp. Resistance (°C) |
|---|---|---|---|
| PVC | 10–15 | 10¹²–10¹³ | 70–105 |
| XLPE | 25–35 | 10¹⁴–10¹⁵ | 90–125 |
| EPDM (Vultac) | 20–30 | 10¹⁴–10¹⁵ | 100–150 |
As you can see, EPDM with Vultac crosslinking holds its own against more commonly used materials like XLPE, especially in terms of thermal resistance and long-term stability.
🔥 Thermal Stability: Keeping Cool Under Pressure
One of the biggest challenges for cable materials is thermal aging. Over time, exposure to heat can cause materials to degrade, crack, or lose flexibility. Vultac helps combat this by creating a dense, stable crosslinking network that resists thermal breakdown.
Studies have shown that EPDM compounds with Vultac crosslinking can maintain their mechanical and electrical properties even after thousands of hours at elevated temperatures. For example, a 2019 study published in Polymer Degradation and Stability found that EPDM cables cured with Vultac retained over 90% of their tensile strength after 3,000 hours at 135°C.
That’s like putting a steak in the oven at 300°F and finding it still tender after a week. Okay, maybe not that dramatic, but you get the idea.
🧼 Chemical and Environmental Resistance
Cables often have to survive in harsh environments—exposed to oils, solvents, ozone, UV light, and even seawater in offshore applications. Vultac-crosslinked EPDM is particularly good at resisting:
- Ozone cracking (a common issue with rubber exposed to air)
- UV degradation (thanks to the stability of the crosslink network)
- Oil and solvent resistance (important in automotive and industrial settings)
- Moisture absorption (critical for underwater and outdoor cables)
A 2021 paper in Journal of Applied Polymer Science demonstrated that Vultac-cured EPDM showed significantly lower swelling when immersed in mineral oil compared to other crosslinking systems. This is a big deal in automotive wiring, where cables are often exposed to engine fluids.
🔧 Processability: Making Life Easier for Manufacturers
From a manufacturing standpoint, Vultac offers several advantages:
- Consistent cure profiles across different batches
- Low scorch risk (prevents premature curing during processing)
- Compatibility with standard rubber processing equipment
- Reduced blooming (migration of sulfur to the surface, which can cause tackiness)
Blooming, by the way, is kind of like when your chocolate bar gets that white film on the surface—it’s not dangerous, but it looks weird and can affect adhesion in downstream processes. Vultac 7-HS, for example, is specifically formulated to minimize blooming, making it a favorite among cable producers.
🌍 Sustainability and Safety
In today’s world, sustainability is no longer optional—it’s a necessity. Arkema has responded to this by developing low-odor, low-emission versions of Vultac, such as Vultac 20S, which reduces volatile organic compound (VOC) emissions during curing.
Additionally, Vultac is used in halogen-free flame-retardant (HFFR) cable compounds, which are increasingly preferred in public buildings, transportation systems, and marine applications. These compounds don’t release toxic halogen gases when burned, making them safer in fire situations.
A 2020 report by the European Committee for Electrotechnical Standardization (CENELEC) highlighted the importance of HFFR materials in reducing smoke and toxicity in cable fires, further cementing Vultac’s role in sustainable cable design.
📚 References (Selected)
- Polymer Degradation and Stability, Vol. 167, 2019 – Long-term thermal aging of EPDM compounds.
- Journal of Applied Polymer Science, Vol. 138, Issue 15, 2021 – Oil resistance of sulfur-crosslinked EPDM.
- Rubber Chemistry and Technology, Vol. 93, No. 2, 2020 – Vulcanization mechanisms and crosslinking efficiency.
- CENELEC Technical Report CLC/TR 50588-1:2020 – Fire performance of cables in public buildings.
- Arkema Technical Data Sheets – Vultac product line specifications.
- Journal of Materials Science, Vol. 55, Issue 21, 2020 – Advances in cable insulation materials.
🧩 Vultac Around the World: Global Applications
From the skyscrapers of Shanghai to the wind farms of Texas, Vultac is a global player in the cable industry. It’s used in:
- Power cables for utilities and renewable energy systems
- Automotive wiring (especially in engine compartments)
- Railway signaling and traction cables
- Marine and offshore cables
- Building and construction wiring
In Japan, for instance, Vultac is a key component in the JR East Shinkansen bullet train cables, where reliability and fire safety are paramount. In Europe, it’s used extensively in smart grid infrastructure and data center cabling.
🤝 The Human Side of Vultac
Behind every chemical compound is a team of scientists, engineers, and technicians who bring it to life. Arkema’s R&D teams work closely with cable manufacturers to tailor Vultac formulations to specific needs.
One engineer from a major European cable manufacturer shared in a 2022 industry forum:
“Vultac gives us the flexibility to fine-tune our compounds without compromising on performance. It’s like having a reliable co-pilot in the lab.”
And that’s the beauty of Vultac—it’s not just a product, it’s a partnership. It adapts, it evolves, and it empowers manufacturers to push the boundaries of what cables can do.
🧠 Final Thoughts: The Future of Vultac
As the world moves toward smart cities, electric vehicles, and renewable energy, the demand for high-performance, sustainable cables will only grow. Vultac is well-positioned to meet that demand, offering a blend of technical performance, environmental responsibility, and manufacturing flexibility.
In the years ahead, we can expect to see Vultac playing a role in:
- High-temperature superconducting cables
- Flexible DC transmission systems
- Hybrid and electric vehicle (EV) charging infrastructure
- Undersea data cables for global internet connectivity
And who knows? Maybe one day, Vultac will even find its way into space cables—because even satellites need insulation.
✨ In Summary
- Vultac is a family of sulfur-based crosslinking agents from Arkema.
- It enhances the mechanical, electrical, and thermal properties of EPDM rubber used in cable insulation and jacketing.
- It offers controlled cure profiles, low odor, and compatibility with halogen-free formulations.
- It’s used globally in power, automotive, rail, marine, and industrial applications.
- It supports sustainability goals through low emissions and fire-safe compounds.
So the next time you plug in your phone, turn on a light, or ride a train, take a moment to think about the invisible hero inside that cable—Vultac, quietly doing its job, one crosslink at a time. ⚡
“In a world full of electrons rushing to get somewhere, Vultac makes sure they don’t take any detours.” — Unknown cable poet.
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