I get asked this question a lot: "Which is better, polycarbonate or nylon filament?" It's tempting to think there's a simple answer. But the 'stronger is better' advice ignores the fact that material selection is a trade-off triangle—strength, temperature resistance, and chemical compatibility rarely peak in a single polymer. Let me break this down by what you're actually trying to do.

Why the "One is Better" Question is the Wrong Starting Point

In my role coordinating material sourcing for industrial maintenance and production, I've handled over 200 rush orders for replacement parts in just the last 18 months. The worst failures I've seen weren't because an engineer picked the wrong material between polycarbonate and nylon. They failed because they asked the wrong question first.

The question isn't which material is universally stronger. It's: what is the failure mode you're trying to avoid? Bending? Melting? Cracking from chemical exposure? Each of these points to a different material, and sometimes, to something outside the standard thermoplastic category entirely.

Let's define nylon first, because there's a lot of confusion there, especially around the term "natural nylon."

Defining Nylon: The Misunderstood Workhorse

When people ask "define nylon," they're usually picturing the synthetic polyamide. Nylon is a condensation polymer, typically polyamide 6 or 6,6. It's strong, tough, and has good abrasion resistance. But here's where it gets tricky.

"Natural nylon" isn't a separate material class. It refers to the undyed, unmodified base polymer—usually a translucent off-white color. This was true 20 years ago when almost all nylon was used in its raw form. Today, "natural nylon" on a spec sheet usually just means no color additives. It doesn't mean it's a more pure or higher-grade material. The phrase is a historical artifact.

So when a client says they "need natural nylon" for a bushing or gear, I always push back: what are the temperature and chemical conditions? Because standard natural nylon (PA6 or PA66) absorbs moisture, which changes its dimensions and mechanical properties. That's why Dupont developed specific grades like Zytel with modified crystallinity. But I'm getting ahead of myself—let's get to the main comparison.

Scenario A: When Polycarbonate Makes More Sense Than Nylon Filament

If your part needs to maintain dimensional stability in varying humidity, or it needs high impact resistance at room temperature, polycarbonate is your answer. Nylon filament will swell with moisture absorption. I've seen a nylon gear seize up in a textile machine after a weekend shutdown in a humid plant. The tolerances shifted just enough.

For transparent covers, sight glasses, or housings where you need to see internal components, polycarbonate is the obvious choice. Its optical clarity is far superior to any nylon. If the application is static, indoors, and below 80°C (176°F), polycarbonate is often the cheaper and more reliable option.

Typical use case for this scenario: A protective window on a food processing machine where it won't see chemicals stronger than cleaning detergents.

Scenario B: When Nylon Filament is the Clear Winner (Polycarbonate Won't Work)

Nylon, particularly glass-filled grades, wins on fatigue resistance and durability under sliding friction. If your part is a gear, a bushing, or a cam, nylon's self-lubricating properties and wear resistance outperform polycarbonate. Polycarbonate under continuous sliding load will generate heat and fail faster due to its higher coefficient of friction.

For under-hood automotive applications or near an oven, nylon's higher melting point (around 220°C vs polycarbonate's 147°C for standard grades) is critical. Polycarbonate will soften and deform. Nylon will hold.

Typical use case: A conveyor guide rail in a bakery where heat is present and the part experiences constant friction.

But here's the kicker—in either scenario, if the part needs to survive contact with oils, solvents, or aggressive chemicals, both may fail. That's where you've gotta look at the specialty materials.

Scenario C: When You Need to Stop Debating Basics and Call in the Big Guns—Dupont Elastomers and Teflon Coating

If your application involves high temperatures (above 120°C continuous), exposure to chemicals, or extreme dynamic stress, looking at polycarbonate vs nylon is a waste of time. You need to think about the Dupont portfolio.

For sealing applications or parts that require flexibility with chemical resistance, Dupont elastomers like Viton (FKM) or Kalrez (FFKM) are the go-to. They can handle temperatures where standard nylon would melt and oils where polycarbonate would craze and crack. I recall a pump failure at a chemical plant last year—the original part was nylon, but it was degrading from exposure to ketones. Swapping to a custom-fabricated Kalrez seal wasn't cheap, but it solved the failure permanently.

And then there's Teflon coating (PTFE). People think of it as a non-stick pan spray. In industrial settings, applying a Dupont Teflon coating to a metal or even a plastic substrate gives you the chemical inertness and low friction of PTFE without the creep issues of pure PTFE. Is it the cheapest option? No. But in high-value applications where downtime costs thousands per hour, the cost is trivial.

Here's a specific example I've used before: In March 2024, 36 hours before a client's production line restart, their process called for a fluoropolymer lining in a pipe section. Standard nylon or polycarbonate wouldn't cut it—the process fluid was a chlorinated solvent at 90°C. We sourced a Dupont Teflon-coated metal component. Normal turnaround was 2 weeks. We paid an 80% rush premium on the $4,000 base cost. Delivered in 36 hours. The client's alternative was a full line shutdown costing $12,000 per day.

So How Do You Decide Which Scenario You're In?

Here's a simple triage you can apply right now:

  1. Check the operating temperature. Over 100°C continuous? Nylon and polycarbonate are both risky. Move to scenario C.
  2. Check the chemical exposure. Oils, solvents, fuels? Standard nylon and polycarbonate will degrade. Look at elastomers or PTFE coatings.
  3. Check the failure mode. Is it a static part or a moving part? Gears and bearings point to nylon or even UHMWPE. Transparent parts point to polycarbonate.

There's something satisfying about finally matching the material to the job. After all the back-and-forth on spec sheets, seeing a system that runs without unplanned downtime—that's the payoff. You won't find that in a generic "polycarbonate vs nylon" blog post. You find it by understanding your real constraint.

Oh, and one more thing: don't rely on memory for specs. I've made that mistake. Always verify the continuous temperature rating and chemical compatibility chart with the supplier before committing to a material.