Hi,
I am working on PA12 and want to increase the thermal stability of this polymer using radiation. Does anyone know which additive I can used to make PA12 radiatable? It is needed to be mentioned that this material is being used in medical field, so the additive must have FDA approval. Moreover, if someone knows other methods to improve thermal stability of PA12, would be also great.
Thank you in advacne.
Best regards,
Omid
Dear Omid Izadi, may be it is wise to avoid additives, just by playing on the following options :
- increase degree of crystallinity
- increase MW by using chain extenders
- introduce fair crosslinks
My Regards
Omid, your best source of advice might be the antioxidant manufacturers. See if Ciba Geigy is still in this business...my work in this was a ways back. Most likely you can use a radical trap like an oligomeric hindered phenol, synergistically combined with a peroxide decomposer. Mechanism of oxidation of PA12 is likely to be the same as polyolefins. Radiation blows a storm of free radicals throughout the polymer, which react with any oxygen dissolved, and continue reacting with atmospheric oxygen if it can diffuse in.
Abdelkader BOUAZIZ
Dear Abdelkader,
Thanks for your reply. could you please explain more the usage of the chain extenders? it is being used as additive or as sth like compound which can be used as granules to be mixed with main material during injection molding process?
moreover, a bit explanation for the fair crosslinks would be also great.
Thank you in advance
best regards,
No thanks. May be you are confusing between extenders fillers and chain extenders (or sometimes called chain extension). Its role is to link chain ends to increase MW. By doing so mechanical and stability are both enhanced.
https://www.researchgate.net/publication/309365650_Effects_of_Diisocyanate_and_Polymeric_Epoxidized_Chain_Extenders_on_the_Properties_of_Recycled_PolyLactic_Acid
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