title: Ammonia diffusion through Nalophan™ bags.
abstract: The aim of the work is to verify the diffusion rate of ammonia through the Nalophan™ film that constitutes the sampling bag, considering storage times ranging from 1 to 26 h. The ammonia decay over time was evaluated using gas-chromatography for the quantification of ammonia concentration inside the bag. The research assesses the roles of both of ammonia and water concentration gradients at the polymeric film interface on the diffusion process. The results show that both the ammonia concentration gradient and, in a less pronounced way, the water concentration gradient are the main 'engines' of ammonia diffusion. Double bags seem to represent a simple solution for preventing ammonia losses during storage. Another interesting result concerns the role of the bag surface on the ammonia diffusion rate: the higher the surface/volume (S/V) ratio, the higher the ammonia diffusion rate through the polymeric film.
authors.affiliation: Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy E-mail: selena.sironi@polimi.it.
authors.forename: Selena
authors.initials: S
authors.lastname: Sironi
authors.affiliation: Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy E-mail: selena.sironi@polimi.it.
authors.forename: Lidia
authors.initials: L
authors.lastname: Eusebio
authors.affiliation: Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy E-mail: selena.sironi@polimi.it.
authors.forename: Licinia
authors.initials: L
authors.lastname: Dentoni
authors.affiliation: Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy E-mail: selena.sironi@polimi.it.
authors.forename: Laura
authors.initials: L
authors.lastname: Capelli
authors.affiliation: Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy E-mail: selena.sironi@polimi.it.
authors.forename: Renato
authors.initials: R
authors.lastname: Del Rosso
mesh_terms: D000641:Ammonia / Q000737:chemistry*; D004058:Diffusion; D011092:Polyethylene Glycols / Q000737:chemistry*; D011093:Polyethylene Terephthalates
chemical_list: D011093:Polyethylene Terephthalates; D011092:Polyethylene Glycols; D000641:Ammonia