Why ABS Plastic Isn't Always the Answer: An Avient Quality Manager's Story

The Phone Call That Started It All

Back in March 2024, I was sitting in our lab reviewing a new batch of thermoplastic tubes for a medical customer—clear tubes with a tight bend radius that needed to hold up under repeated pump pressure. My phone rang, and it wasn't the medical customer. It was a manufacturer who makes plastic Birkenstocks, those sandals with the contoured footbed that appear on every sidewalk in summer. They had a cracking issue in the toe strap area, and they asked the question I hear a lot: is ABS plastic strong?

And honestly? Yeah, ABS is strong. It's rigid, impact-resistant, easy to process, and usually cheaper than most alternatives. In my early days, I probably would've said "use ABS for everything." But over years of reviewing materials, I've learned that "strong" doesn't mean the same thing in every application. That's the reason our quality process exists.

When On Paper Isn't Enough

The customer had already switched to ABS for the straps. Their team figured more strength would equal fewer failures. On paper, it worked. The straps passed initial bench tests. But in the field, the cracks came back. The stress at the toe strap connection was too much for a rigid material that doesn't like repeated bending.

So I asked them to send samples. We ran tensile tests per ASTM D638 and notched Izod per ASTM D256. The ABS did fine again—no arguments, it's strong. But when we placed it side by side with an Avient TPE grade from our lab, the difference became obvious. The TPE flexed and snapped back. The ABS held a bend, then whitened, then showed micro-cracks. I've seen that happen gradually until a part fails completely after a few thousand cycles.

That side-by-side comparison changed how I think about specs. We kept the samples on the lab bench for a week. Every time I walked past, I found myself looking at the ABS sample the way a consumer might: stiff, almost brittle. Our account manager joked that we should do a blind feel test. So we did, with our own team. Nine out of ten people picked the TPE sample as "more premium" based on touch alone. They didn't know what it was. They just knew it felt better.

The Two-Week Tug-of-War

Needless to say, that changed the conversation. The customer went back and forth for two weeks—ABS offered cost savings and a proven supply chain, but the TPE felt like the right answer for their brand. I've seen that hesitation before. The spreadsheet says one thing; your gut says another. Honestly, I didn't blame them. Switching materials is never a small decision.

The owner called me twice a week, sometimes just to talk through the numbers. He had a spreadsheet with ABS on one side and TPE on the other. Every time we talked, I could hear the same tension: the ABS price was lower, but the TPE was the material he'd want to put his name on. That's the kind of decision that keeps a quality person up at night.

And the plastic Birkenstock line wasn't the only thing on their plate. They also manufacture thermoplastic tubes for medical equipment—the ones that carry fluids and need to bend without kinking. They'd been using a generic PP compound. It worked, but it wasn't reliable enough for the tighter bend radius the new design required. We tested ABS as an alternative. The results were mixed, and I remember saying, "ABS is strong, but it's not the best choice when you need repeated flexing and chemical resistance." That's exactly where a specialty TPU or TPE can help—it absorbs the stress instead of resisting it.

The Numbers Speak (and So Does the Hand Feel)

After the pilot, the data came in. The new TPE straps passed 50,000 flex cycles in our lab test. I'm not rounding—that's the actual log entry. The return rate for the sandals dropped by about 30% over the following quarter, if I remember correctly. And the medical tube product passed all its required tests. The end customers probably didn't consciously notice the material change. But they noticed. That's the thing about quality: it doesn't always get credit, but it always gets noticed.

What I'd Tell Anyone Specifying Materials

People think the extra cost of a better material is just a cost. Actually, the real cost is a product that fails and makes your brand look bad. If a customer picks up a sandal and the strap feels brittle, they don't say "the strap is too rigid." They say "this brand is cheap." If a tube kinks under a hospital bed, the clinician doesn't blame the polymer. They blame the supplier who didn't think it through.

So next time you're settling on a spec, ask yourself: what does this material say about my brand? Because material choice is a brand decision before it's an engineering one. And if you want to avoid the cracks showing up in the field, look at the total cost—not just the per-pound price.

If you're in the middle of a similar material decision, our team at Avient can help. We have the lab data, the industry experience, and the range of materials to compare. Set up an Avient login on our customer portal—it's the easiest way to request datasheets and talk to someone who's tested more polymers than they've eaten hot meals. I'd rather help you spec it right the first time than call you about a cracked batch later.

That phone call in March turned into a relationship that's still going strong. The customer still uses ABS in some parts, by the way—not everything needs to be flexible. But the parts that touch skin and bend under load? They're TPE now. And that's exactly how it should be.