I'm a quality/compliance manager at a rubber & plastics company. I review every material batch before it reaches customers—roughly 200 items a year—and I've rejected 11% of first deliveries in 2024 for spec deviation or missing documentation. These are the questions I get from buyers, answered straight.

  • Is TPU like silicone?
  • How transparent is Pirelli's sustainability report data, really?
  • What should I look for on the Pirelli website?
  • What should a proper o-ring kit include?
  • Can I use Sunlu TPU for production parts?
  • TPU patch kits vs. rubber patch kits: what's the difference?
  • How do I verify material claims?

Is TPU like silicone?

No, and assuming they're interchangeable is the kind of mistake that costs real money.

When I first started working with TPU, I assumed it would behave like silicone. Both are soft and rubbery, and in a quick hand-feel test, it's easy to confuse them. Three years and one cracked fuel-line prototype later, I learned how wrong that assumption was.

TPU (thermoplastic polyurethane) is tough, abrasion-resistant, and can be melted and reprocessed. It holds up well against oils, grease, and repeated flexing. Silicone is a thermoset: you can't re-melt it, but it survives roughly -50°C to 200°C and stays flexible at temperatures where TPU stiffens. Silicone also resists UV and aging better, but it tears more easily and doesn't tolerate fuel or petrochemicals.

So think of it this way: both feel rubbery, but they're engineered for different jobs. Specify by function—chemical exposure, temperature range, abrasion—not by how the material feels in your hand.

How transparent is Pirelli's sustainability report data?

The phrase "data transparency" gets thrown around loosely, so let's be specific. Pirelli publishes an annual sustainability report following the GRI framework; the version covering FY2023 data is out as of early 2025. It includes scope 1, 2, and 3 emissions, energy sourcing with the renewable share, waste, water, and health & safety metrics—plus an independent assurance statement from a third-party auditor. Pirelli also holds B Corp certification (they were the first tire manufacturer to earn it), which brings its own audit cycle.

What I don't like about "data transparency" is the implication that there are no limits. There are limits. Raw-material emissions—natural rubber, synthetic rubber, steel—still rely on industry-average estimates instead of actual supplier data, and the report says so. That's not a scandal; it's typical for the sector as of 2025, at least. What matters is whether methodology and boundaries are disclosed clearly enough that a buyer can compare one report against another. In Pirelli's case, they are.

What should I look for on the Pirelli website?

The Pirelli website is useful, but treat it as a starting point, not a spec database.

For tires, you'll find OE fitments, technical datasheets, and the EU tire label values for fuel efficiency, wet grip, and rolling noise. That's verifiable information that matches what's printed on the physical tire label.

For industrial rubber goods—flooring, rubber webbing, TPU tubes, TPU patch kits—the product pages describe the material family and general performance, but the numbers you need for a specification (durometer, tensile strength, operating temperature range) usually live in a technical datasheet you have to request from sales. I've implemented a rule for our own procurement: no datasheet, no purchase order. A product page without a spec PDF is marketing.

What should a proper o-ring kit include?

An o-ring kit is only useful if you know exactly what you're installing. I've opened kits where rings were tossed into a box with no identification (unfortunately, still common). That's a quality failure waiting to happen.

A proper kit should include:

  • Several material classes (NBR, FKM, EPDM, silicone), each ring identifiable
  • Hardness rating—because "70 Shore A" is not universal even among general-purpose rings
  • Sizes referenced to ISO 3601-1 or AS568A dash numbers
  • A chemical compatibility chart mapping each compound to the media it can handle
  • Storage and shelf-life guidance: no UV, no ozone (keep rings away from electric motors), no stretching, no high heat

If you can't identify a ring's compound, you can't verify chemical compatibility. In our Q1 2024 quality audit, we found two maintenance shops using look-alike rings from nondescript "assorted o-ring" kits—one EPDM, the other NBR. Both looked identical. One was incompatible with the oil in the system. That's the kind of failure you don't discover until the equipment is already down.

Can I use Sunlu TPU for production parts?

I get this one frequently, because Sunlu makes good, reasonably priced TPU filament, and their 95A TPU prints well on hobbyist machines. For prototypes, spacers, and gaskets that don't seal, it's useful.

For production parts, the answer is no, for three reasons. First, 3D-printed TPU has layer lines, so parts tend to leak along those layers under pressure. Second, printed parts are anisotropic: strong in one direction, weak in another. Third, consumer filament doesn't guarantee batch-to-batch consistency. I've seen two spools from the same box behave differently after a supplier changed a process parameter without any public notice.

That doesn't mean Sunlu is a bad product. It means it's a different product category. If your part must seal, hold fluid, or handle load, specify injection-molded or extruded TPU with a datasheet, a hardness range, and a test method. That's what "industrial" means to a quality manager.

TPU patch kits vs. rubber patch kits: what's the difference?

A TPU patch kit is designed for TPU products: inflatable paddleboards, packrafts, air mattresses, and TPU inner tubes (which Pirelli also makes). TPU patches bond through heat or a polyurethane adhesive formulated to fuse the same material class—not merely sit on the surface.

A rubber patch kit, like the classic bicycle tube repair set, uses a butyl patch and solvent-based vulcanizing cement. It works on butyl rubber tubes, not TPU tubes. When solvent-based rubber cement meets TPU, the solvent can swell and attack the TPU before a proper bond forms. I've seen that exact repair fail in cold-temperature testing: the patch looked fine at 20°C and lifted at 5°C.

The quality check before any repair: identify the base material first, then match the patch to it. A good kit lists exactly which plastics and rubbers it can reliably repair. If it doesn't, pick one that does.

How do I verify material claims?

You can't verify everything as a buyer. What you can do is focus on the properties that will break your part, and demand evidence.

Ask for third-party test data on the property that matters. For seals, that's compression set and chemical compatibility. For TPU, abrasion and flex fatigue. When you get a number, ask how it was measured. If the supplier can't name the test method—ASTM D2240 for hardness, ISO 1817 for chemical resistance—the number doesn't mean much. I often tell suppliers: I do not care what the number is, only what standard produced it.

Run an incoming inspection on the first batch. A durometer check and dimensional sampling catch most spec drift. We digitized that process last year, and it cut our verification turnaround from five days to two. Of the first deliveries I've reviewed this year, roughly 11% still come back with a spec deviation or missing paperwork.

And please, cut the word "standard" out of contracts unless a standard number follows it. I said "standard TPU" in a purchase order once (this was back in 2023). The supplier heard "whatever they had on the shelf." The result was a $22,000 redo and a delayed launch. Now every contract I touch names the material, hardness range, and test method. That single change has eliminated more quality arguments than anything else I've done.