Radiopaque medical TPU: barium-sulphate-filled polycarbonate for X-ray visibility
Polycarbonate TPU carrying a barium sulphate (BaSO4) filler makes the device itself visible under X-ray, removing the need for welded marker bands in cardiovascular, neuro and peripheral devices.
Why radiopacity matters
In cardiovascular, neuro-interventional and peripheral devices, "not being able to see it" is a persistent pain point. Once a catheter, guidewire or stent cover enters the body, the clinician has to locate it under fluoroscopy — for intra-operative positioning and for post-operative follow-up.
Nilun solves this at the material level: a polycarbonate TPU that carries a barium sulphate (BaSO4) filler, so the polymer itself is visible under X-ray rather than relying on a separately welded metal marker ring.
How barium-sulphate radiopacity works
Barium sulphate has a high atomic number, so X-rays barely pass through it. Dispersed at a 20%–40% loading in a polycarbonate TPU matrix, it produces a clear contrast against soft tissue on a standard cardiovascular angiography system.
Unlike a traditional add-on marker ring, the radiopacity is in the material itself — it forms in one piece during extrusion and does not depend on any secondary attachment step.
What it delivers
- Real-time visibility — the device is clearly identifiable on a standard angiography system during the procedure.
- One-piece radiopacity — no extra metal marker ring or additional process step; extrusion carries the radiopacity with it.
- Two adjustable contrast levels — 20% BaSO4 for light visibility and 40% for high contrast, matched to the procedure.
- Broad coverage — radiopaque guidewire jackets, vascular stent covers, balloon substrates, and neuro-interventional and peripheral devices.
Grade selection
The radiopaque option is configured onto three aliphatic polycarbonate grades. Aromatic polycarbonate grades (85A / 55D) complement the aliphatic set; selection is driven by the device's stiffness and mechanical requirements.
| Grade | Hardness | Radiopacity | Typical use |
|---|---|---|---|
| NLMD6575A | 75A | 20% / 40% BaSO4 | Cardiovascular catheters, radiopaque guidewire jackets, neuro & peripheral devices |
| NLMD6585A | 85A | 20% / 40% BaSO4 | Vascular stent covers, balloon substrates, radiopaque structural layers |
| NLMD6595A | 95A | 20% / 40% BaSO4 | Rigid radiopaque components, long-term cardiovascular implants |
Built on a domestic-substitution system
Radiopacity is not a single point capability — it sits on a full domestic system. Nilun was the second company worldwide to certify a full medical TPU range (70A–85D, January 2024), the five implant-grade polycarbonate grades carry a national master-file (MAF) registration that downstream device makers can reference for their own NMPA submission, and a 52-week intramuscular implant study (13/26/52 weeks) reported a 52-week irritation index of 0.0, no different from the negative control.
Grade performance, radiopacity loading and compliance status are subject to the latest TDS, biocompatibility reports and NMPA registration documents.