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Gamma Compatible Materials

Radiation Stability of Selected Medical Grade Polymers
( KGY)
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.
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.

( KGY)
Polyimides 10,000  
Polymethylpentene 20 Subject to oxidation degradation. Avoid use.
Polyphenylene Sulfide 1,000  
Polypropylene, Radiation Stabilized
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.
(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 for a material qualification technical information report and sterilization standard.