FDA’s safety evaluation of food contact materials is driven by probable exposure assessments based on combining migration data with consumer usage information. Migration models are useful tools in calculating potential migration of polymer additives and contaminants as an alternative to experimental migration testing. The generally recognized Piringer diffusion model defines a polymer parameter, AP, to describe the basic diffusion behavior of a polymer matrix in relation to its migrants. However, AP values for ethylene vinyl alcohol (EVOH) of any ethylene content have not been defined in a publicly available resource. EVOH is a random copolymer of ethylene and vinyl alcohol frequently used as a high-oxygen barrier within multilayer flexible packaging structures. Blown film of EVOH 48 mol% ethylene was tested as a monolayer after physical delamination from a custom LDPE/EVOH/LDPE/EVA structure. Diffusion coefficients (DP), permeability coefficients, and solubility coefficients of surrogate migrants (methylene chloride, toluene, ethyl butyrate, and chloroform) were determined by an isostatic permeation method using an organic vapor permeation analyzer. Diffusivity, permeability, and solubility of tested migrants in EVOH increased with experimental temperature. DP values for EVOH were determined in the range of 10-9 to 10-10 cm2/s at temperatures of 121°C (retort sterilization) and 100°C (boiling water sterilization). At temperatures of 121°C and 100°C, mean AP values for EVOH were calculated as -0.7 and 0.4, respectively. As a reference for these same migrants, AP values for PET were calculated as -1.7 at 121°C and -2.2 at 100°C. The higher AP values of EVOH relative to PET are likely due to several factors which result in increased migrant mobility within the polymer, including its high 48 mol% ethylene content, its lower Tg, and the closer proximity to its Tm. The mean polymer specific constant for EVOH 48 mol% is AP' = 0.0 with tau = 0.

Permeation properties of EVOH with high ethylene content for use in migration modeling of food contact materials

256th National Meeting (2018)

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