Kinetic Water Sorption in Poly(ethylene furanoate) Compared to Poly(ethylene terephthalate)

Poly(ethylene furanoate) (PEF), which is a bio-based, performance-enhanced furanic analog to poly(ethylene terephthalate) (PET), is being investigated as a possible replacement for PET in the beverage packaging industry. The current work investigates concentration dependence in diffusion coefficients for water at 35°C in both amorphous PEF and PET over the entire water activity range. PEF exhibits increased chain rigidity compared to PET as evidenced by reduced diffusion coefficients over the entire water activity range. Transport is governed by simple Fickian diffusion up to ~0.6 activity, after which long-term non-Fickian relaxations induce morphological changes in both polymers. Various diffusion models are used to describe the kinetic sorption curves, including the simple Fickian model, the Berens-Hopfenberg model, and the model proposed by Long and Richman. Additionally, activation energies of water diffusion calculated from measurements at 15, 25, 35, and 45°C and a sorption interval of 0.1 – 0.2 activity will be presented.