Resin pellets aging and degradation investigation from long term in situ experiment: first results

Abstract

Experimental studies in recent years highlight the presence of an increasingly high quantity of microplastics worldwide [1]. The "resin pellets" represent a significant share among the first generation microplastics in the millimeter range (from 1 to 5 mm). They disperse in the environment, even unintentionally, during transport, storage and processing and recent studies show that their content varies from 3% to about 30% of all microplastics surveyed on beaches [2]. A three-years experiment was carried out on a simulated beach and in marine water in Santa Teresa Bay (Gulf of La Spezia, Italy). In detail, special cages have been installed on the underwater observatory, LabMARE coastal station [3], placed at ten meters deep. The submarine station is equipped with a sensor for monitoring environmental parameters, recording data every 10 min. The experiment, aimed at investigating the behavior of plastic items and HDPE, PP, PLA and PBAT pellets, began on March 3, 2020 and is still ongoing. Here, the comparison between the properties of the raw pellets and those placed in the two different environments after six months, is discussed. Through chemical, spectroscopic and thermal analyses (GPC, SEM, FTIR-ATR, DSC, TGA) of granules, variations in color, surface morphology, chemical composition, thermal properties and molecular weight, and polydispersity of materials are analysed to show the different influences of environmental conditions.