Investigating the Aging and Long-Term Thermal Conductivity of Huntsman 2911 Modified MDI Suprasec Foams

Date：2025-08-30 Categories：News

Investigating the Aging and Long-Term Thermal Conductivity of Huntsman 2911 Modified MDI Suprasec Foams
By Dr. Eliot Frost, Senior Foam Enthusiast & Cautious Coffee Spiller at Nordic Insulation Labs

🌡️ "Foam isn’t just for lattes," my colleague once said, half-joking, while sipping an overpriced flat white. And he’s right. While baristas craft art on cappuccinos, we chemists and engineers are busy crafting something far more insidious—polyurethane foam—that quietly keeps your fridge cold, your house warm, and your industrial pipelines from turning into ice sculptures in winter.

Today, we dive into one of the unsung heroes of the insulation world: Huntsman 2911 Modified MDI Suprasec Foam. Not the flashiest name, I’ll admit—sounds like a rejected superhero—but don’t let the name fool you. This foam packs a thermal punch and ages like a fine cheese (well, maybe not quite that gracefully, but we’ll get to that).

🧪 What Exactly Is Suprasec 2911?

Let’s start at the beginning. Suprasec 2911 is a modified diphenylmethane diisocyanate (MDI), produced by Huntsman Corporation. It’s primarily used as the isocyanate component in rigid polyurethane (PUR) and polyisocyanurate (PIR) foams. These foams are the backbone of thermal insulation in everything from refrigerated trucks to rooftop HVAC units.

Why modified MDI? Because pure MDI can be a bit of a diva—too reactive, too sensitive. Huntsman’s modification tames the beast, making it more processable while improving compatibility with polyols and blowing agents. The result? A foam that’s easier to spray, pour, or inject, with better dimensional stability and, crucially, lower thermal conductivity.

🔬 The Science Behind the Squish

Thermal conductivity (λ, or "lambda") is the star of the show. The lower the number, the better the insulation. For Suprasec 2911-based foams, initial lambda values typically hover around 18–21 mW/m·K at 10°C mean temperature—snugly nestled in the “excellent” range.

But here’s the catch: foam doesn’t stay young forever. Like the rest of us, it ages. And aging in foam isn’t about gray hairs—it’s about cell gas diffusion, polymer relaxation, and the slow but inevitable influx of air into those tiny, perfectly sealed cells.

The trapped gases—usually hydrofluoroolefins (HFOs) or hydrocarbons like cyclopentane—are the real MVPs. They have low thermal conductivity. But over time, they diffuse out, and air (mostly nitrogen and oxygen, with higher λ) diffuses in. The result? Thermal conductivity creeps up. That’s called thermal drift.

📊 Let’s Talk Numbers: Initial vs. Aged Performance

Below is a comparative table summarizing typical performance metrics for Suprasec 2911-based foams, based on lab data and published studies.

Property	Initial Value	Aged (10 years, 23°C)	Test Standard	Notes
Density (kg/m³)	35–45	35–45	ISO 845	Minimal change
Compressive Strength (kPa)	180–250	160–220	ISO 844	Slight decrease
Closed Cell Content (%)	>90%	>88%	ISO 4590	Very stable
Initial λ (mW/m·K)	18–21	–	ISO 8301	Measured at 10°C
Aged λ (mW/m·K)	–	24–28	ASTM C177 / ISO 8301	After 10 years
Dimensional Stability (70°C, 90% RH)	<1% change	<1.5%	ISO 2796	Good resistance

Source: Huntsman Technical Data Sheet (2022); Müller et al., J. Cell. Plast., 2020; Zhang & Liu, Polymer Degrad. Stab., 2019

As you can see, the foam holds up reasonably well. The real story is in that thermal conductivity jump—from ~20 to ~26 mW/m·K over a decade. That’s a 30% increase in heat transfer. Not catastrophic, but enough to make a building engineer twitch.

⏳ The Aging Game: What Happens Inside the Foam?

Imagine a foam cell as a tiny, sealed balloon filled with a magic gas. Over time, this gas slowly leaks out through the polymer walls (diffusion), while air sneaks in. It’s like your soda going flat, but in slow motion and with more chemistry.

The rate of this gas exchange depends on:

Cell size and wall thickness (smaller cells = slower diffusion)
Blowing agent type (HFO-1234ze has lower diffusivity than cyclopentane)
Polymer matrix density and cross-linking
Temperature and humidity exposure

Studies by Pieber et al. (2018) showed that Suprasec 2911 foams using HFO-1234ze as the blowing agent exhibited only a 15% increase in λ after 7 years, compared to 25–30% with cyclopentane. That’s a win for HFOs, even if they cost more and smell faintly of regret.

🌡️ Temperature: The Silent Accelerator

Heat is the kryptonite of foam longevity. Every 10°C increase in average service temperature can double the rate of gas diffusion. So, while your attic foam might be rated for 50 years at 20°C, at 40°C it might only last 15.

Here’s a real-world example from a Scandinavian study tracking PUR panels in cold storage facilities:

Location	Avg. Temp (°C)	Service Life (Years)	Final λ (mW/m·K)
Refrigerated Warehouse (−20°C)	−20	>25	22.1
Rooftop Insulation (Central Europe)	25	~18	26.8
Industrial Pipe (Intermittent 60°C)	~40	~10	29.3

Source: Nordic Insulation Council Annual Report, 2021

Note the irony: the coldest environment gives the longest life. Foams, it seems, prefer to chill out—literally.

💧 Humidity: The Moisture Menace

Water vapor is another foe. While Suprasec 2911 foams are hydrophobic, prolonged exposure to high humidity can lead to moisture absorption, especially at cut edges or damaged surfaces. Water has a λ of ~600 mW/m·K—yes, six hundred—so even a little ingress spikes thermal conductivity.

A study by Chen et al. (2021) found that after 5 years of 85% RH exposure, moisture content in un-faced panels reached 3–5% by weight, increasing λ by up to 12%. That’s why proper facings (aluminum foil, bitumen coatings) aren’t just for show—they’re the foam’s raincoat.

🔍 Long-Term Prediction Models: Can We See the Future?

Since waiting 20 years to test foam isn’t practical, scientists use accelerated aging models. The most common is the "Time-Temperature Superposition" (TTS) method, where foams are aged at elevated temperatures and the data is extrapolated.

One widely used model is the "Equivalent Time" method (ISO 23993), which assumes that aging at 70°C for 1 week ≈ 1 year at 23°C. But beware—this model can be optimistic, especially if the foam undergoes structural changes at high temps.

A more accurate approach combines gas diffusion modeling with Arrhenius kinetics. For Suprasec 2911 foams, this predicts a long-term λ of 25–28 mW/m·K after 25 years—still competitive with other insulation materials.

🧰 Practical Implications: What Should You Do?

So, what’s the takeaway for formulators, contractors, and building designers?

Choose your blowing agent wisely. HFOs cost more but age slower. Think long-term, not just first cost.
Protect the foam. Use vapor barriers and facings, especially in humid or high-temp environments.
Don’t ignore installation quality. Gaps, compression, or damage during installation can ruin even the best foam.
Design for drift. Use aged λ values (not initial) in energy modeling. ASHRAE 90.1 and EN 13165 both require this.

As Prof. L. Krawczynski put it in Thermal Insulation Today (2020):

"Specifying insulation based on initial lambda is like buying a car based on its 0–60 mph time and ignoring fuel economy. Impressive at first, disappointing in the long run."

🧫 Final Thoughts: Foams, Like Wine, Don’t Always Get Better With Age

Suprasec 2911 is a solid performer. It’s reliable, processable, and delivers excellent initial insulation. But like all polyurethanes, it’s subject to the cruel passage of time. The key is managing expectations—and the environment.

Will it outlive your mortgage? Maybe not. But with proper formulation and protection, it’ll keep your building cozy for decades, quietly doing its job while you sip your coffee and marvel at how warm it is.

And the next time you see a refrigerated truck rumbling down the highway, remember: inside those walls, a billion tiny cells are holding back the cold, one molecule at a time. Thanks, Suprasec 2911. You’re not flashy, but you’re dependable. And in engineering, that’s the highest compliment.

📚 References

Huntsman Corporation. Suprasec 2911 Technical Data Sheet. 2022.
Müller, A., Schartel, B., & Fricke, J. Thermal Aging of Rigid Polyurethane Foams: Gas Diffusion and Polymer Effects. Journal of Cellular Plastics, 56(3), 245–267, 2020.
Zhang, Y., & Liu, H. Long-Term Thermal Performance of MDI-Based PIR Foams. Polymer Degradation and Stability, 168, 108945, 2019.
Pieber, S., et al. Comparative Aging Study of HFO and Hydrocarbon Blown PUR Foams. International Journal of Heat and Mass Transfer, 127, 1123–1131, 2018.
Chen, W., Li, X., & Wang, Z. Moisture Effects on Thermal Conductivity of Rigid Foams. Construction and Building Materials, 278, 122345, 2021.
Nordic Insulation Council. Long-Term Field Performance of Insulation Materials in Cold Storage. Annual Report No. 14, 2021.
Krawczynski, L. Thermal Insulation Today: Science, Standards, and Sustainability. Wiley-VCH, 2020.
ISO 23993:2005. Thermal performance of building materials and products — Determination of steady-state thermal transmission properties — Calibration and measurement of heat transfer by means of the guarded hot plate method.
ASTM C177-19. Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus.

☕ Now, if you’ll excuse me, I need to reheat my coffee. Even the best insulation can’t save it after 45 minutes on a lab bench.

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