Wastes from Agricultural Silage Film Recycling Line as a Potential Polymer Materials.

Jerzy Korol,Aleksander Hejna,Klaudiusz Wypiór,Ewelina Chmielnicka,Krzysztof Mijalski

doi:10.3390/polym13091383

Abstract

The recycling of plastics is currently one of the most significant industrial challenges. Due to the enormous amounts of plastic wastes generated by various industry branches, it is essential to look for potential methods for their utilization. In the presented work, we investigated the recycling potential of wastes originated from the agricultural films recycling line. Their structure and properties were analyzed, and they were modified with 2.5 wt % of commercially available compatibilizers. The mechanical and thermal performance of modified wastes were evaluated by tensile tests, thermogravimetric analysis, and differential scanning calorimetry. It was found that incorporation of such a small amount of modifiers may overcome the drawbacks caused by the presence of impurities. The incorporation of maleic anhydride-grafted compounds enhanced the tensile strength of wastes by 13–25%. The use of more ductile compatibilizers—ethylene-vinyl acetate and paraffin increased the elongation at break by 55–64%. The presence of compatibilizers also reduced the stiffness of materials resulting from the presence of solid particles. It was particularly emphasized for styrene-ethylene-butadiene-styrene and ethylene-vinyl acetate copolymers, which caused up to a 20% drop of Young’s modulus. Such effects may facilitate the further applications of analyzed wastes, e.g., in polymer film production. Thermal performance was only slightly affected by compatibilization. It caused a slight reduction in polyethylene melting temperatures (up to 2.8 °C) and crystallinity degree (up to 16%). For more contaminated materials, the addition of compatibilizers caused a minor reduction in the decomposition onset (up to 6 °C). At the same time, for the waste after three washing cycles, thermal stability was improved. Moreover, depending on the desired properties and application, materials do not have to go through the whole recycling line, simplifying the process, reducing energy and water consumption. The presented results indicate that it is possible to efficiently use the materials, which do not have to undergo the whole recycling process. Despite the presence of impurities, they could be applied in the manufacturing of products which do not require exceptional mechanical performance.

Highlights

IntroductionFor the preservation of fodder by ensilage, mostly polyethylene (PE) films are used, mainly low-density polyethylene (LDPE)
Primary use are suitable for landfilling or utilization in a waste incineration plant
Material recycling represents the most straightforward way of managing plastic waste and, at the same time, it enables attainment of new polymer-based materials which can be reused in other sectors than agriculture

Summary

Introduction

For the preservation of fodder by ensilage, mostly polyethylene (PE) films are used, mainly low-density polyethylene (LDPE). It is a low-cost material that can be processed into products meeting the criteria related to agricultural films’ optical and physical properties [2]. In southern European countries, plastics are mainly used for crop protection (in greenhouses, cultivated tunnels, mulching). It is associated with unfavorable climate conditions, so films are applied to improve the microclimate for crop growth [3]. The foil used to cover the silage stocks could be reused

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