Views: 0 Author: Site Editor Publish Time: 2026-05-11 Origin: Site
Selecting the right transparent material for injection-molded medical connectors is more challenging than it seems. You need optical clarity, dimensional stability, biocompatibility, and — most importantly — no yellowing after sterilization.
If you’re designing transparent medical connectors (e.g., luer locks, Y-sites, tubing connectors), this guide compares six proven materials that meet the following criteria:
✅ Injection moldable
✅ Medical grade (ISO 10993 or USP Class VI)
✅ High transparency
✅ Resistant to yellowing after sterilization (gamma, EtO, e-beam)
✅ Latex‑free
Best for: general‑purpose transparent connectors requiring impact resistance
Tritan™ (Eastman) is a copolyester that has become the go‑to material for many medical injection‑molded parts.
Property | Performance |
|---|---|
Transparency | Glass‑like, >90% light transmission |
Yellowing after sterilization | ✅ Excellent stability under gamma, EtO, e‑beam |
Impact resistance | Very high (comparable to PC, but BPA‑free) |
Chemical resistance | Good (oils, alcohols) |
Biocompatibility | ISO 10993, USP Class VI |
Latex‑free | ✅ Yes |
Typical applications: luer connectors, filter housings, manifolds, single‑use medical device components.
Proven grades: Eastman Tritan™ MX711, Ensinger TECADUR MT TR natural
Best for: high‑purity applications and precision thin‑wall parts
COC is a high‑purity amorphous thermoplastic with extremely low extractables and outstanding dimensional stability.
Property | Performance |
|---|---|
Transparency | Glass‑clear, good light transmission |
Yellowing after sterilization | ✅ Stable under gamma, EtO, steam (121°C) |
Extractables | Extremely low (protects drug stability) |
Water absorption | <0.01% (excellent dimensional stability) |
Biocompatibility | Meets medical standards, BPA/phthalate‑free |
Latex‑free | ✅ Yes |
Typical applications: pre‑filled syringe barrels, microfluidic chips, diagnostic consumables, vial containers.
Proven grade: TOPAS® 6013M‑07 (heat resistant to 130°C)
Best for: cost‑sensitive, high‑volume connectors
Ordinary PP yellows after sterilization. But specially formulated radiation‑stabilized PP grades maintain clarity and color stability.
Property | Performance |
|---|---|
Transparency | Good (slight haze, lower than Tritan/COC) |
Yellowing after sterilization | ✅ Stable (with proper grades) |
Cost | Low |
Low‑temperature toughness | Good down to 0°C (special grades) |
Biocompatibility | Meets YY/T 0242, non‑cytotoxic, non‑pyrogenic |
Latex‑free | ✅ Yes (polyolefin base) |
Typical applications: syringe barrels, needle caps, luer slip fittings, lab consumables.
Proven grades: JPP RP348P (gamma/EtO resistant), Exxon PP9074MED, Sinopec PPR‑MT20
Best for: connectors that frequently contact alcohol or lipid‑containing drugs
CYROLITE® (Evonik) is specifically designed for medical applications requiring excellent chemical resistance.
Property | Performance |
|---|---|
Transparency | High clarity |
Yellowing after sterilization | ✅ Turns to a permanent blue‑green tint (not yellow) |
Chemical resistance | Excellent against alcohols (isopropanol), lipids, and plasticizers from PVC tubing |
Biocompatibility | USP Class VI, ISO 10993‑1, BPA‑free |
Latex‑free | ✅ Yes |
Typical applications: luer connectors, IV spikes, needle hubs, Y‑sites, valve components, filter housings.
Proven grades: CYROLITE® Protect 2, CYROLITE® MD H12
Best for: soft, elastic connectors or sealing elements
SEBS is a thermoplastic elastomer that offers flexibility without plasticizers. Hydrogenated grades resist yellowing.
Property | Performance |
|---|---|
Transparency | Good clarity, no fogging over time |
Yellowing risk | ✅ Low (hydrogenated grades reduce oxidation) |
Hardness | Adjustable (soft and flexible) |
Extractables | Very low VOC, low residual catalysts |
Biocompatibility | USP Class VI, ISO 10993 |
Latex‑free | ✅ Yes (developed as latex/PVC alternative) |
Typical applications: port seals, syringe plungers, soft tubing connectors, gaskets.
Proven grades: LCY high‑transparency SEBS, Mediprene® series
Best for: injection‑molded connectors that require both clarity and toughness
TPU offers a wide hardness range. For yellowing resistance, choose aliphatic TPU over standard aromatic grades.
Property | Performance |
|---|---|
Transparency | High clarity (grade‑dependent) |
Yellowing after sterilization | ✅ Excellent for aliphatic TPU; aromatic grades may yellow |
Hardness | Very wide range – from soft elastomer to rigid engineering plastic |
Biocompatibility | ISO 10993, latex‑free, phthalate‑free |
Injection moldability | Excellent – many dedicated injection grades |
Typical applications: rigid connectors (luer locks), device housings, catheters (soft grades), seals.
Proven grades: Lubrizol Tecoplast™ (aromatic, high hardness), Nan Liu UREAMAX® (aliphatic, non‑yellowing), Covestro Texin® Rx
Material | Transparency | Yellowing Resistance | Hardness | Cost | Best Use Case |
|---|---|---|---|---|---|
PCT‑G (Tritan) | ⭐⭐⭐⭐⭐ | Excellent | Rigid | Medium‑High | General connectors (top pick) |
COC | ⭐⭐⭐⭐⭐ | Excellent | Rigid | High | Precision / high‑purity parts |
Medical PP | ⭐⭐⭐ | Good (special grades) | Rigid | Low | Cost‑sensitive high volume |
CYROLITE | ⭐⭐⭐⭐ | Good (blue‑green tint) | Rigid | Medium | Alcohol/lipid contact |
SEBS | ⭐⭐⭐⭐ | Good (hydrogenated) | Soft | Medium | Soft seals, elastic parts |
Aliphatic TPU | ⭐⭐⭐⭐ | Excellent | Rigid/Adjustable | Medium‑High | Non‑yellowing tough connectors |
Your Priority | Recommended Material |
|---|---|
Best overall transparency + no yellowing | PCT‑G (Tritan™) |
Ultra‑high purity + precision | COC (TOPAS®) |
Low cost + high volume | Medical PP (radiation‑stabilized) |
Frequent alcohol or lipid contact | CYROLITE® |
Soft / elastic connector elements | SEBS |
Non‑yellowing tough connectors (injection molded) | Aliphatic TPU |
Always request ISO 10993 or USP Class VI certification from your supplier.
Even if a material is listed as “medical grade,” final device validation is your responsibility.
For non‑yellowing requirements, ask for accelerated aging test reports (QUV or gamma sterilization) with ΔE values.
