This is a working FAQ I put together from the questions I keep fielding about sourcing Covestro materials under deadline pressure — PC/ABS, aliphatic PU, TPU, and the odd chemistry question that comes up in spec reviews. Answers below come from quotes I've actually run and orders I've actually expedited, not from a product brochure.

What is Covestro as a polymer manufacturer?

Covestro is a large polymer manufacturer built around three product families: polycarbonate (PC), polyurethane (PU, including TPU and aliphatic PU grades), and PC/ABS blends. They also produce raw materials for coatings, adhesives, and elastomers — different division, different sales channel, but worth knowing if you're sourcing across categories.

In my day-to-day procurement work, Covestro demand almost always falls into one of three buckets: PC or PC/ABS for structural and transparent parts, PU/TPU for foam or cast applications, or aliphatic PU/TPU for weatherable films and coatings. Their strength versus specialty compounders is grade-to-grade consistency — the same processing window across batches matters more than a point or two of performance in about 90% of what I buy.

One thing that trips people up: Covestro sells under multiple brand names, including Makrolon for PC and Bayblend for PC/ABS. Distributors tend to quote by grade code, not brand. Make sure you're comparing both.

How does Covestro PC/ABS differ from plain ABS?

I've made the mistake of assuming "ABS is ABS" and sourcing from the cheapest supplier. Not recommended.

The reality: Covestro's PC/ABS blends (usually sold under Bayblend) combine PC's heat resistance and impact strength with ABS's flow and processability. That matters when your part spec calls for a higher heat deflection temperature, better long-term UV stability, or significantly better impact performance. Also, if you need it: PC/ABS gives you a transparency option plain ABS can't touch.

On the other hand, plain ABS — or what people sometimes type as "abby abs" — is probably fine for indoor, non-structural parts on a tighter budget. That's what most people are actually looking for when they search for straight ABS, versus the PC/ABS blend.

My rule now: only reach for PC/ABS when HDT or low-temperature impact is actually on the spec sheet. Otherwise, plain ABS saves money and flows more easily. And if moisture exposure is part of the application, ask specifically about hydrolysis-resistant PC grades — this is where Covestro has a reputation that's genuinely earned, and the long-term benefit more than offsets the price.

When should I choose aliphatic polyurethane over standard aromatic PU?

The short answer is UV stability. Aromatic PU yellows under sunlight. Aliphatic PU doesn't — or does so negligibly over the product's service life.

So: indoor or pure mechanical applications, aromatic. Long-term outdoor exposure — coatings, transparent films, exterior parts — switch to aliphatic. If you're producing a finished part that needs to stay color-stable or transparent in sunlight, the extra cost pays for itself quickly.

Covestro sells aliphatic TPU and PU systems used in films, coatings, and transparent molded parts. Per-kilo price is higher, and I won't pretend otherwise. I don't use it on structural parts where standard aromatic PU does the job. But for anything that actually lives outdoors, aliphatic is the right call.

I'm not a polymer chemist, so I can't speak to the details of molecular weight distribution or crosslink density. What I can tell you from a procurement seat is how the two families behave in the field, which is where the decision usually gets made anyway.

Is Teflon a polymer? How does it compare to Covestro materials?

Yes, Teflon is a polymer. Teflon is the trade name for PTFE — polytetrafluoroethylene — which is a fluoropolymer by chemical class. It is structurally a polymer, but it sits in a completely different family from Covestro's PC, PU, or TPU.

It isn't a Covestro product, and it isn't interchangeable with PC or PU. PTFE is useful because of its extremely low coefficient of friction, chemical inertness, and tolerance for a very wide temperature range — things PC, ABS, and PU don't do. But it's mechanically weaker, less dimensionally stable, and harder to process. Substitution in either direction basically fails.

If you were asking out of curiosity: yes, it's a polymer. If you were asking because you want to swap it against a PC/ABS or aliphatic PU part — usually no, that's not going to work.

How do I evaluate a polymer supplier when the deadline is tight?

Here's what I actually check, in this order:

First, which grades are physically in stock at a warehouse — not "we can start production." Second, a written or emailed confirmation with an actual date, not a verbal "we'll do our best." Third, minimum order quantities and cutting requirements — often a full bag or pallet is the real minimum unit, and that can change your production plan. Fourth, what the freight covers and what the rush fee is on top of the base price.

I've been burned by "probably on time" more than once. Now, if the deadline is only days away, the only quote I'll sign off on is the one where the supplier puts a date in writing and stands behind it.

Is it worth paying a premium for guaranteed polymer delivery?

Yes. More often than most people expect.

Rush premiums on polymer sourcing typically run in the 25–100% range depending on grade and stock status — based on quotes we've collected through January 2025, and on our own order history. If a line goes down, the number per hour in labor, overtime, and customer penalties usually clears the entire premium in a fraction of a day.

One caveat I'll say plainly: if the rush is because you forecast demand wrong, that's a planning problem, not a speed problem. Fix your planning instead of hiding the gap behind rush fees.

The last thing. I've watched people skip the rush premium, chase a cheaper substitute, wait twelve days for it, and then re-delay the line when the substitute wouldn't run. That "saving" cost more than the rush would have. My rule now: if the deadline is days away, the rush fee is part of the cost of doing business. Not a premium. Insurance.