materials Article Biodegradable Polymers for the Production of Nets for Agricultural Product Packaging Francesco Paolo La Mantia 1,2, * , Manuela Ceraulo 2 , Paolo Testa 1 and Marco Morreale 3   Citation: La Mantia, F.P.; Ceraulo, M.; Testa, P.; Morreale, M. Biodegradable Polymers for the Production of Nets for Agricultural Product Packaging. Materials 2021, 14, 323. https:// doi.org/10.3390/ma14020323 Received: 1 December 2020 Accepted: 6 January 2021 Published: 9 January 2021 Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional clai- ms in published maps and institutio- nal affiliations. Copyright: © 2021 by the authors. Li- censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and con- ditions of the Creative Commons At- tribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Department of Engineering, University of Palermo, Viale delle Scienze, 90128 Palermo, Italy; paltest94@gmail.com 2 Consorzio INSTM, Via Giusti 9, 50121 Firenze, Italy; manuela.ceraulo@gmail.com 3 Faculty of Engineering and Architecture, Kore University of Enna, Cittadella Universitaria, 94100 Enna, Italy; marco.morreale@unikore.it * Correspondence: francescopaolo.lamantia@unipa.it Abstract: It is well known that the need for more environmentally friendly materials concerns, among other fields, the food packaging industry. This regards also, for instance, nets used for agricultural product (e.g., citrus fruits, potatoes) packaging. These nets are typically manufactured by film blowing technique, with subsequent slicing of the films and cold drawing of the obtained strips, made from traditional, non-biodegradable polymer systems. In this work, two biodegradable polymer systems were characterized from rheological, processability, and mechanical points of view, in order to evaluate their suitability to replace polyethylene-based polymer systems typically used for agricultural product net manufacturing. Furthermore, laboratory simulation of the above-mentioned processing operation paths was performed. The results indicated a good potential for biodegradable polymer systems to replace polyethylene-based systems for agricultural product packaging. Keywords: biodegradable polymer; fruit packaging; fibers; films; elongational flow 1. Introduction Nets for packaging of fruits and vegetables are usually made from blown films of high-density polyethylene (HDPE) or blends of polyethylenes (PEs) cut into small slices, and then cold drawn. To date, the production of polymer films used for this application relies on polyolefins, either neat or blended, and the main mechanical properties of interest in such application are rigidity and elongation at break. Furthermore, a fundamental property for this application is weldability, which cannot be easily obtained by only using HDPE; this issue is overcome by blending it with a low-density polyethylene (LDPE) or metallocene (M-PE), which make the processing much easier. Therefore, in order to find suitable candidates for replacing polyolefins in these applications, the research should be focused on filmability properties, as well as the ability to be efficiently cold drawn and to give rise to slices with a good rigidity and deformability. At the same time, the large use of plastics in the packaging industry has been increasing the environmental concern; therefore, the interest in the use of biodegradable polymers to replace conventional poly- mers, in order to reduce the environmental impact caused by inappropriate disposal, has grown [1]. Poly(lactic acid) (PLA) is a thermoplastic, biodegradable, and biocompatible polymer that can be produced from renewable resources [2]. PLA is known to have low toughness at room temperature and low melting resistance compared to conventional polymers, with these factors actually hindering its application in large-scale processes, such as industrial blown film extrusion, blowing, and foaming, where stability to the melt is a fundamental factor [3,4]. The melting resistance of PLA must be, therefore, improved in order to widen its processing frame and therefore its field of application. Copolymeriza- tion, the addition of plasticizers, and blending with other polymers are some of the main ways to achieve improvements in the properties of PLA [5]. PLA blends with polymers Materials 2021, 14, 323. https://doi.org/10.3390/ma14020323 https://www.mdpi.com/journal/materials