Dear Colleagues,

It is well known that polymers, thanks to their versatility and their high resource efficiency, have become key materials for strategic sectors such as packaging, transportation, building and construction, electrical and electronic, agriculture, medical and sport devices. Furthermore, polymers have allowed for the development of products and services in many other sectors that would be not possible otherwise. Considering the fast growing population, the high security demand, and the control of climate change, our society is called to choose the most efficient solution, in order to guarantee the most sustainable development. Plastic materials and products offer these advantages, because they are extremely resource efficient during their service-life, and they help us to avoid waste, save energy, and decrease CO₂ emissions.

In order to achieve the best engineering solution, the optimization of the barrier behavior is actually of crucial importance. In contrast to glass or metal packaging materials, plastic packaging is permeable to molecules such as gas, water vapor, and organic vapor, as well as the aromas, flavors, and additives that are present food, when polymers are employed in the field of food. The transfer of these molecules could range from high to low, depending on the barrier properties of such materials. Knowledge of the permeation behavior, together with the solution and diffusion of such molecules throughout the polymer films is of crucial importance, especially for polymers used in the field of food, where contamination from the external environment has to be avoided, while preserving the internal package’s atmosphere. The final properties of the packaging materials could be influenced by engineering procedures such as manufacturing, handling, and distribution, but the final barrier properties are strictly correlated to the intrinsic structure of the polymers, such as the degree of crystallinity, crystalline/amorphous phase ratio, thermal and mechanical treatment, food contact, nature of chemical groups present into the polymer, degree of crosslinking, thermal behavior, molecular weight, and so on. Furthermore, the intrinsic composition of the packed food, such as the pH, fat content, aroma compound, and so on, could influence the sorption characteristics of these materials, while the temperature and relative humidity may affect their barrier behavior.

The aim of this Special Issue is to collect and provide an overview on the state-of-the-art of the barrier behavior of polymers, either fossil fuel-based or bio-based, that are used for packaging applications. This Special Issue could be considered as a chance for the academic and industrial world to present an overview of novel polymers, with focussed attention on their barrier performances in order to establish a structure–property relationship. The mechanisms and pathways of molecules’ transport behavior throughout polymer films will be taken into account.

Research papers, as well as reviews, are welcome.

Prof. Valentina Siracusa
Dr. Carlo Ingrao
Guest Editors

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• Gas barrier behavior
• Gas diffusion through polymer films
• Gas barrier properties of polymers
• Gas barrier behavior of bio-based/biodegradable polymers
• Gas permeability
• Water vapor permeability
• Gas barrier-properties relationship of polymers
• Barrier properties for a sustainable packaging
• Barrier behavior of food packaging materials
• High gas barrier polymers
• Gas barrier behavior of polymers after stressed treatments
• Water vapor permeability after stressed treatments