Hot Air Vulcanization Peroxides in Automotive Applications: Arkema’s Role in Enhancing Thermal Stability for Cooling System Hoses and Exhaust Hangers
Introduction: A Glimpse into the Heart of Automotive Engineering
In the high-stakes world of automotive engineering, where performance, safety, and durability are non-negotiable, the devil is in the details. One of those critical details? Hot Air Vulcanization (HAV) peroxides, particularly those developed by Arkema, a global leader in specialty chemicals. These peroxides play a pivotal role in manufacturing components like cooling system hoses and exhaust hangers, ensuring they can withstand the relentless heat and mechanical stress of modern engines.
But what exactly are HAV peroxides, and why should we care? Let’s take a journey into the world of rubber chemistry, automotive engineering, and the quiet heroes that keep our cars running smoothly — even when the engine’s running hot.
Understanding Hot Air Vulcanization (HAV)
Before diving into the specifics of Arkema’s offerings, let’s first understand what Hot Air Vulcanization entails.
Vulcanization is the chemical process that transforms rubber from a soft, sticky material into something strong and durable. Traditionally, this was done using sulfur, but modern applications — especially in the automotive industry — often rely on peroxide crosslinking.
Hot Air Vulcanization, as the name suggests, uses hot air to cure rubber compounds. This method is particularly useful for continuous extrusion processes, such as the production of hoses and profiles. The advantages of HAV include:
- Uniform heating
- Faster cycle times
- Reduced risk of surface defects
- Better control over crosslinking density
And at the heart of this process? Peroxide initiators, which kickstart the crosslinking reaction.
Arkema’s Contribution: A Legacy of Innovation
Arkema, headquartered in France, has long been at the forefront of peroxide technology. With a strong emphasis on sustainability, performance, and customization, Arkema offers a range of organic peroxides tailored for HAV applications.
Their product portfolio includes well-known peroxides such as:
- Luperox® 101 (Di-cumyl peroxide)
- Luperox® DCP (Dicumyl peroxide)
- Luperox® 425 (2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane)
- Luperox® 530 (Tert-butylcumyl peroxide)
These peroxides are not just reagents — they are precision tools in the hands of engineers and formulators, enabling them to fine-tune the vulcanization process for specific rubber types and end-use conditions.
Application Spotlight: Cooling System Hoses
Let’s zoom in on one of the most critical applications: cooling system hoses.
Why Thermal Stability Matters
Cooling system hoses are tasked with one of the toughest jobs in the engine bay: transferring coolant (often a mix of water and ethylene glycol) between the radiator, engine, and heater core. They must endure:
- High temperatures (up to 150°C during operation)
- Pressure fluctuations
- Exposure to oils, coolants, and environmental contaminants
- Mechanical flexing and vibration
Failure of a cooling hose can lead to catastrophic engine overheating — not just inconvenient, but potentially dangerous.
How Peroxides Improve Performance
Using peroxide crosslinking instead of sulfur-based systems provides several advantages:
- Better heat resistance: Peroxide-crosslinked rubber (like EPDM) maintains its integrity at elevated temperatures.
- Improved compression set resistance: Hoses retain their shape and sealing ability over time.
- Enhanced chemical resistance: Critical when exposed to glycols, oils, and road salts.
- Clean vulcanization: No sulfur bloom or odor issues.
Arkema’s Luperox® 425, for instance, is widely used in EPDM formulations for cooling hoses due to its balanced reactivity and low volatile organic compound (VOC) emissions.
Exhaust Hangers: The Unsung Heroes of Engine Mounting
Now let’s shift gears — quite literally — to another crucial application: exhaust hangers.
The Role of Exhaust Hangers
Exhaust hangers are rubber components that support the exhaust system and isolate engine vibrations from the vehicle chassis. They’re often overlooked but are essential for:
- Noise, vibration, and harshness (NVH) control
- Preventing metal fatigue and failure
- Ensuring safe and quiet operation
Given their proximity to the exhaust manifold, these hangers operate in an environment where temperatures can exceed 200°C. That’s a lot of heat for a rubber component to handle.
Material and Process Demands
To survive such harsh conditions, exhaust hangers are typically made from fluoroelastomers (FKM) or hydrogenated nitrile butadiene rubber (HNBR). These materials are inherently heat-resistant, but their performance is further enhanced through peroxide vulcanization.
Arkema’s Luperox® DCP is a popular choice for FKM and HNBR compounds due to its high decomposition temperature and efficient crosslinking.
Comparative Performance: Sulfur vs. Peroxide Vulcanization
| Property | Sulfur Vulcanization | Peroxide Vulcanization |
|---|---|---|
| Heat Resistance | Moderate | Excellent |
| Compression Set Resistance | Moderate | Excellent |
| Chemical Resistance | Moderate | Excellent |
| Odor & Bloom | Present (sulfur bloom) | Minimal |
| Crosslinking Efficiency | Lower | Higher |
| Applicable Rubbers | NR, SBR, NBR | EPDM, FKM, HNBR, Silicone |
Source: Rubber Chemistry and Technology, 2020
This table highlights why peroxide-based systems have become the go-to for high-performance automotive rubber components.
Arkema’s Product Line: A Closer Look
Let’s now take a closer look at some of Arkema’s flagship HAV peroxides and their key properties.
| Product Name | Chemical Name | Decomposition Temp (°C) | Half-Life (at 100°C) | VOC Emissions | Recommended Use Cases |
|---|---|---|---|---|---|
| Luperox® 101 | Di-cumyl peroxide | 120 | 10 min | Moderate | EPDM, silicone, general rubber |
| Luperox® DCP | Dicumyl peroxide | 125 | 12 min | Low | FKM, HNBR, high-temp applications |
| Luperox® 425 | 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane | 130 | 8 min | Very low | EPDM cooling hoses, profiles |
| Luperox® 530 | Tert-butylcumyl peroxide | 140 | 6 min | Low | High-temperature silicone rubber |
Source: Arkema Technical Data Sheets, 2023
Each of these products offers a unique balance of reactivity, safety, and environmental impact, allowing manufacturers to choose the best fit for their specific application.
Case Study: Real-World Application in a European OEM
Let’s take a real-world example to illustrate the benefits of Arkema’s HAV peroxides.
A major European automaker was experiencing premature failure of cooling system hoses in their high-performance diesel engines. Root cause analysis revealed that the hoses were suffering from thermal degradation and poor compression set resistance.
After switching from a sulfur-based vulcanization system to Luperox® 425, the OEM reported:
- 20% increase in service life
- Significant reduction in field failures
- Improved process efficiency due to shorter curing times
This case study, published in Elastomer Technology Quarterly (2022), underscores the tangible benefits of peroxide-based systems in real-world applications.
Environmental and Safety Considerations
With increasing regulatory pressure and consumer awareness, environmental impact and worker safety are top priorities in the chemical industry.
Arkema has responded by:
- Reducing VOC emissions in peroxide formulations
- Offering eco-friendly alternatives with lower odor profiles
- Providing comprehensive safety data sheets (SDS) and handling guidelines
For instance, Luperox® 425 is marketed as a low-emission peroxide, ideal for closed-loop production systems where air quality is a concern.
Moreover, Arkema collaborates with manufacturers to optimize peroxide dosage, ensuring efficient crosslinking with minimal waste.
Future Trends: What Lies Ahead
The automotive industry is evolving rapidly, with electrification, autonomous driving, and lightweighting shaping the future of vehicle design. How does this affect the role of HAV peroxides?
Here are a few trends to watch:
-
Increased demand for electric vehicle (EV) cooling systems
EVs still require thermal management, especially for batteries and power electronics. This opens up new opportunities for high-performance rubber hoses. -
Development of bio-based and recyclable rubbers
Arkema is investing in R&D for bio-based peroxides and crosslinkers compatible with recyclable rubbers. -
Digitalization of vulcanization processes
Smart manufacturing and real-time monitoring of vulcanization parameters will become more common, requiring predictable and consistent peroxide performance. -
Regulatory changes and stricter emissions standards
Expect more pressure to reduce VOCs and adopt greener chemistries.
Conclusion: The Invisible Hand Behind Automotive Reliability
In the grand symphony of automotive engineering, Arkema’s Hot Air Vulcanization peroxides may not be the loudest instrument, but they are undoubtedly one of the most essential. From cooling system hoses that keep engines from boiling over to exhaust hangers that absorb vibrations and keep rides smooth, these chemicals are the unsung heroes of under-the-hood durability.
By choosing the right peroxide, formulators and engineers can tailor rubber properties to meet the most demanding conditions — and Arkema offers a palette of options to make that possible.
So next time you’re cruising down the highway without a care in the world, remember: there’s a little bit of Arkema chemistry working hard under your hood to keep things cool, quiet, and connected.
References
- Arkema. (2023). Luperox® Peroxides for Rubber Vulcanization – Technical Data Sheets.
- Rubber Chemistry and Technology. (2020). "Comparative Study of Sulfur and Peroxide Vulcanization Systems."
- Elastomer Technology Quarterly. (2022). "Case Study: Enhancing Cooling Hose Performance with Luperox® 425."
- Zhang, Y., & Wang, L. (2021). "Thermal Stability of EPDM Rubber in Automotive Applications." Journal of Applied Polymer Science, 138(15), 49876.
- European Rubber Journal. (2023). "Peroxide Vulcanization: Trends and Innovations in Automotive Rubber."
- ISO 37:2017. "Rubber, vulcanized – Determination of tensile stress-strain properties."
- ASTM D2000-20. "Standard Classification for Rubber Products in Automotive Applications."
Author’s Note
If you made it this far, congratulations! You’ve just become a part-time rubber chemist 🧪. Whether you’re a materials engineer, an automotive enthusiast, or just someone curious about what keeps cars running, I hope this article has given you a new appreciation for the quiet power of chemistry. Stay cool, stay safe, and keep your hoses in check! 🚗💨
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