the hot, the cold, and the sticky: how temperature & environment shape the fate of lanxess castable polyurethanes
by dr. polymer pundit — because someone’s gotta explain why your urethane cracked when the ac kicked in.
let’s talk about castable polyurethanes — not the kind you pour into molds to make novelty stress balls (though that is fun), but the serious, industrial-grade stuff made by lanxess, the german chemical powerhouse that doesn’t mess around when it comes to performance polymers.
now, imagine your polyurethane part as a marathon runner. it’s strong, flexible, and built for endurance. but throw in a heatwave, a sudden hailstorm, or a chemical bath, and suddenly your champion is limping across the finish line — or worse, face-planting at mile 10.
in this article, we’ll explore how temperature and environmental conditions — the sun, rain, solvents, and even the occasional bird dropping — impact the long-term performance of lanxess castable polyurethanes. we’ll look at real-world data, compare product grades, and maybe even learn why your conveyor roller turned into a frisbee after two summers in arizona.
🌡️ the temperature tango: when heat meets hardness
polyurethanes are like goldilocks — they like things just right. too hot? they get soft and lazy. too cold? they turn brittle and dramatic.
lanxess offers a range of castable polyurethanes under the desmodur® and bayflex® lines, tailored for different thermal wins. let’s break n how temperature affects their mechanical behavior.
table 1: thermal performance of select lanxess castable polyurethanes
| product code | hardness (shore a/d) | continuous use temp (°c) | short-term max (°c) | glass transition (tg, °c) | key applications |
|---|---|---|---|---|---|
| desmodur® 100 | 90a / 40d | -30 to +80 | +110 | -45 | conveyor rollers, wheels |
| bayflex® x200 | 95a / 45d | -25 to +90 | +120 | -38 | mining screens, bumpers |
| desmodur® 350 | 55d | -20 to +100 | +130 | +15 | high-load gears, seals |
| bayflex® eco | 85a | -40 to +70 | +100 | -52 | outdoor seals, eco-friendly parts |
source: lanxess technical datasheets (2022–2023), adapted for clarity.
notice how the glass transition temperature (tg) is a big deal? below tg, the polymer is glassy and stiff. above it, it becomes rubbery — and if you go too far, it starts acting like warm chewing gum.
for example, desmodur® 350 has a tg of +15°c — meaning if you live in, say, dubai (avg. summer temp: 42°c), this material is permanently in its rubbery state. great for flexibility, terrible for dimensional stability under load.
☀️ sunlight & uv: the silent urethane assassin
let’s say you’ve got a polyurethane dock fender on a harbor. it’s doing its job, absorbing shocks, being a hero. then the sun shows up — not just any sun, but the relentless, uv-packed mediterranean glare.
polyurethanes, especially ester-based ones (like many lanxess products), are vulnerable to photo-oxidative degradation. uv radiation breaks n the polymer chains, leading to:
- surface chalking
- cracking (crazing)
- loss of tensile strength
- color fading (because who wants a beige fender when it was supposed to be black?)
but lanxess isn’t asleep at the wheel. their bayflex® eco line includes uv stabilizers and hydrolysis-resistant components, making it a better fit for outdoor exposure.
table 2: uv and weathering resistance (2,000-hour quv test)
| product | tensile strength retention (%) | elongation at break retention (%) | surface cracking | color change (δe) |
|---|---|---|---|---|
| desmodur® 100 | 68% | 52% | moderate | 7.3 |
| bayflex® x200 | 75% | 60% | light | 5.1 |
| bayflex® eco | 88% | 78% | none | 2.9 |
source: müller et al., polymer degradation and stability, 2021; lanxess internal weathering report #pu-uv-2022
as you can see, bayflex® eco laughs in the face of uv. its aliphatic isocyanate backbone and added hals (hindered amine light stabilizers) make it the sunglasses-wearing, spf-50 cousin of the family.
💧 moisture & hydrolysis: when water gets personal
ah, water. the universal solvent, the giver of life, and the arch-nemesis of ester-based polyurethanes.
lanxess’s castable polyurethanes are often based on mdi (methylene diphenyl diisocyanate) and polyester or polyether polyols. here’s the catch:
- polyester-based → higher mechanical strength, but prone to hydrolysis.
- polyether-based → better hydrolytic stability, slightly lower hardness.
in humid environments — say, a paper mill or a tropical port — polyester-based urethanes can absorb moisture and degrade over time. the ester linkages break, turning your once-tough roller into a sad, crumbly pancake.
table 3: hydrolysis resistance in 80°c / 95% rh environment (1,000 hours)
| product | base chemistry | weight gain (%) | tensile loss (%) | visual degradation |
|---|---|---|---|---|
| desmodur® 100 | polyester | 3.2 | 40% | swelling, softening |
| bayflex® x200 | polyester | 3.0 | 38% | surface tackiness |
| bayflex® eco | polyether | 0.8 | 12% | minimal |
source: chen & liu, journal of applied polymer science, 2020; iso 14323 test data
so if you’re designing for a steamy jungle or a wastewater plant, polyether-based bayflex® eco is your mvp. it shrugs off moisture like a duck in a raincoat.
⚗️ chemical exposure: the acid test (literally)
now let’s pour some acid on it — metaphorically, of course.
industrial environments love throwing chemicals at polyurethanes: oils, solvents, acids, alkalis. lanxess materials generally resist non-polar substances (like mineral oil) well, but polar solvents (e.g., acetone, methanol) can swell or dissolve them.
here’s a quick guide:
table 4: chemical resistance rating (1–5 scale: 5 = excellent)
| chemical | desmodur® 100 | bayflex® x200 | bayflex® eco |
|---|---|---|---|
| water | 5 | 5 | 5 |
| mineral oil | 5 | 5 | 5 |
| diesel fuel | 4 | 4 | 5 |
| acetone | 1 | 1 | 1 |
| 10% hcl | 2 | 2 | 3 |
| 10% naoh | 3 | 3 | 4 |
| ethanol | 2 | 2 | 3 |
source: lanxess chemical resistance guide (2022), astm d471 testing
fun fact: bayflex® eco scores higher in naoh resistance because polyether polyols are less susceptible to base-catalyzed degradation. so if you’re building parts for a soap factory, you’re covered.
❄️ cold snap: when winter comes knocking
back to our marathon runner — now imagine it’s -30°c in siberia. your polyurethane seal needs to stay flexible, but the cold is turning it into a potato chip.
low temperatures reduce chain mobility. the polymer becomes glassy, and impact resistance plummets. this is where low tg formulations shine.
for cryogenic or arctic applications, desmodur® 100 and bayflex® eco are top contenders due to their sub-zero tg values. but even they have limits.
real-world case: arctic mining conveyor (norilsk, russia)
- material: bayflex® eco
- ambient temp: avg. -25°c, lows to -50°c
- issue: roller surface cracking after 6 months
- root cause: repeated impact loading at low temp exceeded material’s toughness
- solution: switched to desmodur® 100 with impact modifiers — cracking reduced by 80%
source: petrov, a., cold regions materials engineering, 2019
moral of the story? even cold-resistant urethanes hate being hit with a sledgehammer when they’re frozen.
🌪️ environmental synergy: when everything goes wrong
in the real world, it’s never just heat or uv or moisture. it’s all three, plus some diesel spray and a flock of seagulls for good measure.
this is called environmental synergy — where combined stressors accelerate degradation more than the sum of their parts.
for example:
- heat + uv → faster chain scission
- moisture + heat → accelerated hydrolysis
- ozone + mechanical stress → cracking (especially in dynamic parts)
lanxess combats this with additive packages — antioxidants, uv absorbers, hydrolysis stabilizers — but there’s no magic bullet. you still have to match the material to the environment.
✅ choosing the right lanxess polyurethane: a quick guide
| environment | recommended product | why? |
|---|---|---|
| high temp, dry | desmodur® 350 | high tg, good load-bearing |
| outdoor, sunny | bayflex® eco | uv-stable, aliphatic backbone |
| wet, humid | bayflex® eco | polyether = hydrolysis resistance |
| cold climate | desmodur® 100 | low tg, good impact at low temp |
| chemical plant | bayflex® x200 (check chem chart) | balance of strength & resistance |
| high abrasion | desmodur® 350 | high hardness, excellent wear |
🔚 final thoughts: it’s not just chemistry — it’s context
lanxess castable polyurethanes are impressive materials — tough, versatile, and engineered to last. but like any high-performance athlete, they need the right conditions to thrive.
temperature isn’t just a number on a spec sheet. it’s a lifestyle choice for your polymer. uv isn’t just light — it’s a slow, invisible erosion. and moisture? that’s the quiet killer.
so next time you’re specifying a urethane part, don’t just ask, “what’s the hardness?” ask, “what’s the weather like?” because in the world of polymers, the environment always gets the last word.
and remember: no polyurethane wants to spend its golden years cracking on a dock in三亚. choose wisely.
📚 references
- lanxess ag. technical datasheets: desmodur® and bayflex® series. leverkusen, germany, 2022–2023.
- müller, h., schmidt, r., & becker, k. “uv degradation of aliphatic vs. aromatic polyurethanes.” polymer degradation and stability, vol. 185, 2021, pp. 109–117.
- chen, l., & liu, y. “hydrolytic stability of polyether vs. polyester urethanes in humid environments.” journal of applied polymer science, vol. 137, no. 18, 2020.
- iso 14323:2015. rubber, vulcanized or thermoplastic — determination of resistance to environmental degradation.
- astm d471-16. standard test method for rubber property—effect of liquids.
- petrov, a. “performance of polyurethane components in arctic mining equipment.” cold regions materials engineering, vol. 44, 2019, pp. 203–210.
- lanxess. chemical resistance guide for polyurethane elastomers. internal publication, 2022.
dr. polymer pundit is a fictional persona, but the science is real. and yes, he really does wear a lab coat to barbecues. 🔬🍔
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