|
|
|
| Acrylonitrile/Butadiene/Styrene |
1,000 |
Protected by Benzene ring structure. |
| (ABS) |
|
Avoid high dose on high impact grades. |
| Aromatic Polyesters |
1,000 |
Very stable, retains excellent clarity. Drying is essential. |
| (PET, PETG) |
|
Good in luer connectors. |
| Esters and Ethers |
100 |
|
| Paper, Card, Corrugated, Fibers |
100-200 |
Paper and natural fibers scission, discolor and embrittle. |
| Cellulose Acetate Propiconate and |
100 |
Retains good clarity and impact. |
| Butyrate |
|
|
| Tetrafluroethylene (PTFE) |
5 |
Liberates fluorine gas, disintegrates to powder. Avoid use. |
| Polychlorotrifluoroethylene (ECTFE) |
200 |
|
| Polyvinyl Fluoride |
1,000 |
|
| Polyvinylidene Fluoride (PVDF) |
1,000 |
|
| Ethylene-Tetrafluoroethylene (ETFE) |
1,000 |
|
| Fluorinated Ethylene Propylene (FEP) |
50 |
Avoid use. |
| Polyacetals (Delrin, Celcon) |
5 |
Avoid use due to embrittlement. |
| Polymethylmethacrylate |
100 |
Yellows at 20-40 kGy; clarity recovers partially on aging. |
| Polyacrylonitrile |
100 |
Yellows at 20-40 kGy. |
| Polyacrylate |
100 |
Yellows at 20-40 kGy. |
| Polycyanoacrylate |
200 |
Adhesives function at 100 kGy with less than 30% degradation. |
| Polyamides (Nylons) |
|
|
| Aliphatic & Amorphous Grades |
50 |
Discolours. Avoid thin films and fibers. Dry before molding. |
| Aromatic Polyamide/Polyimide |
10,000 |
High heat/strength grade. |
| Polycarbonate |
1,000 |
Discolours, clarity recovers after aging. Dry before molding. |
| Polyethylene (LDPE, LLDPE, |
1,000 |
Crosslinks to gain strength, loses some elongation. |
| HDPE, UHMPE, UHMWPE) |
|
All polyethylene radiation stable, low density most resistant. |
| |
|
|
| Note: Physical properties of polymers that are irradiated may vary due to: section thickness; molecular weight distribution; morphology; moisture; oxygen levels; and either residual or functional stress. Each polymer must be tested in the specific application under consideration. |
|
|
|
| Polyimides |
10,000 |
|
| Polymethylpentene |
20 |
Subject to oxidation degradation. Avoid use. |
| Polyphenylene Sulfide |
1,000 |
|
| Homopolymer |
20-50 |
Subject to orientation embrittlement. Validate with real time aging. |
| Copolymers of Propylene-Ethylene |
25-60 |
More stable than Homopolymer. |
| Polypropylene, natural |
20 |
Avoid use of unstabilized polypropylene. |
| Polystyrene |
10,000 |
All styrenes are stabilized by Benzene ring structure. |
| Polysulfone |
10,000 |
Amber colour before irradiation. |
| Polyurethane |
10,000 |
Excellent clarity and chemical resistance to stress-cracking. Drying is essential. |
| Polyvinylbutyral |
100 |
Yellows. |
| Polyvinylchloride (PVC) |
100 |
Yellows, can be tinted for colour correction. |
| Polyvinylidene Chloride (PVDC) |
100 |
Yellows, releases HCL. |
| Styrene/Acrylonitrile (SAN) |
1,000 |
Yellows at 40 kGy. |
| Allyl Digylcol Carbonate (Polyester) |
5,000-10,000 |
All thermosets as a class are highly resistant. |
| Epoxies |
1,000 |
Many good formulations available. Success depends on joint design and application process. |
| Phenolics |
50,000 |
|
| Polyesters |
100,000 |
|
| Polyurethanes |
100-1,000 |
Wide formulation variations for urethanes. |
| Butyl |
50 |
|
| Ethylene-Propylene Diene Monomer (EPDM) |
100-200 |
Crosslinks, yellows slightly. |
| Fluoro Elastomer |
50 |
Avoid multiple sterilization. |
| Natural Rubber (Isoprene) |
100 |
Very stable with sulfur or resin cure systems. |
| Nitrile |
200 |
Avoid multiple sterilization. |
| Polyacrylic |
50-200 |
Avoid multiple sterilization. |
| Polychloroprene (Neoprene) |
200 |
Avoid multiple sterilization. |
Silicones
(Peroxide & Platinum Catalyst Systems) |
50-100 |
Crosslink density increases more in peroxide systems than in platinum systems. |
| Styrene-Butadiene |
100 |
Avoid multiple sterilization. |
| Urethanes |
100-200 |
Wide variations in urethane chemistry applied to medical devices. |
* Elastomers:
1) Radiation tolerance is affected by the base polymer and the curing system used. Sulfur and resin cures are more durable.
2) All elastomers are subject to cross-linking. Avoid folds, coils, curves in the shape packaged. Typical sterilization processing dose: 20-50 kGy (2.0-5.0 Mrads).
It is recommended that all materials should be tested thoroughly to verify the compounds’ performance after irradiation. An excellent reference source is the Association for the Advancement of Medical Instrumentation web site at www.aami.org for a material qualification technical information report and sterilization standard. |
