Out With the Old: Advancing the Chemical Cleanliness of Rubber Components

The chemical cleanliness of elastomeric rubber components is not a single material property — it is the cumulative result of every ingredient decision made during compound formulation, from the polymer backbone to the crosslinking system, fillers, antioxidants, plasticizers, and other additives, each of which contributes its own extractables and leachables (E/L) profile to the drug contact surface. This on-demand webinar, presented by Datwyler's Manager of Material Development, provides pharmaceutical formulation scientists, packaging engineers, and regulatory professionals with a chemistry-grounded framework for understanding how modern rubber formulation advances have progressively reduced the E/L burden of elastomeric closures. The session begins with rubber composition fundamentals — elastomer crosslinking chemistry, the role of fillers in providing hardness and rigidity, and the principle that fewer ingredients means lower extractables potential. The evolution of pharmaceutical elastomers is then traced from natural rubber (prone to latex allergy, poor gas barrier, complex crosslinking) through halobutyl (clean crosslinking system, low gas permeability, suitable for accelerator-free cure) to BIMS — brominated isobutylene para-methylstyrene — the polymer basis of FM457, which eliminates rubber oligomer extractables entirely by removing unsaturated C=C bonds that require antioxidants and stabilize radicals after gamma irradiation. Crosslinking system chemistry is examined in detail, with particular attention to accelerator elimination — explaining that halobutyl crosslinking does not require accelerators, removing the primary source of secondary amine and nitrosamine risk that affects older polyisoprene formulations. A comparative case study presents one-year HS-GC/MS (VOC) and GC/MS (SVOC) extraction data for FM257 (classic halobutyl), FM457 (low extractables BIMS), and NeoFlex™ coated FM457 plungers in IPA at room temperature, demonstrating the progressive reduction in extractables profile across the three generations of compound and coating technology.