Ανακύκλωση πολυπροπυλενίου (ΡΡ) με χρήση φυσικών αντιοξειδωτικών

Κουράνου, Διονυσία; Kouranou, Dionysia

dc.contributor.author	Κουράνου, Διονυσία	el
dc.contributor.author	Kouranou, Dionysia	en
dc.date.accessioned	2022-09-28T08:12:41Z
dc.date.available	2022-09-28T08:12:41Z
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/55783
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.23481
dc.rights	Αναφορά Δημιουργού-Όχι Παράγωγα Έργα 3.0 Ελλάδα	*
dc.rights.uri	http://creativecommons.org/licenses/by-nd/3.0/gr/	*
dc.subject	Πρόσθετα	el
dc.subject	Πολυπροπυλένιο	el
dc.subject	Ανακύκλωση	el
dc.subject	Αντιοξειδωτικά	el
dc.subject	Καφές	el
dc.title	Ανακύκλωση πολυπροπυλενίου (ΡΡ) με χρήση φυσικών αντιοξειδωτικών	el
heal.type	bachelorThesis	el
heal.classification	Μηχανική πολυμερών	el
heal.language	el	el
heal.access	free	el
heal.recordProvider	ntua	el
heal.publicationDate	2022
heal.abstract	The use of natural antioxidants as stabilizers for polymers is an innovative and much promising, rising, new trend. This trend is associated with the urgent need for “greener” technologies and ecological commodities, that no longer cause harm to humans or the environment. The natural antioxidants contribute to this end purpose by reducing the additives’ migration, as well as its negative effects. On a second note, in case the natural antioxidants are derived by residual natural sources, such as spent coffee residues, they also serve the principles of circular economy and endorse new ways of re-using old, waste products (upcycling). In this context, there are a numerous current research papers, which examine the isolation of natural antioxidants from natural sources, but only few of them explore the isolation of natural antioxidants from residual natural sources. One of the later, is this forthcoming dissertation. The natural antioxidants isolated from coffee residues were subjected to qualitative methods of analysis and were assessed relatively to their ability to effectively stabilize a post-consumer recycled (PCR) polypropylene, against thermal distress and oxidation, during reprocessing with multiple cycles of extrusion in a single-screw extruder. Specifically, five cycles of extrusion were chosen, in an attempt to simulate the industrial scale of the processing of an old material. The evaluation as to whether the stabilization via refusion-restabilization was successful or not, was achieved by a series of analyzes and quality characterization methods (MFR, TGA, DSC and ATR-FTIR). In particular, in the first stage of this thesis, it was found that the most appropriate process for isolating and receiving the natural antioxidants from spent coffee residues was a conventional method of extraction, under stirring and heating at 60-70°C, with an ethanol:water (70:30) solvent, for 90min of extraction time. In the second stage, a masterbatch of 4.0% concentration of natural antioxidants was prepared in a twin-screw extruder (200°C, 50rpm). In the third stage, the masterbatch was diluted with the recycled polypropylene in a twin-screw extruder (200°C, 70rpm) to a final concentration of 1.0% in antioxidants and then, processed with five cycles of extrusion in a single-screw extruder (190°C, 50rpm). The stabilization effect of the additives for the polypropylene was examined by determining the melt flow rate MFR(190°C, 2.16kg) and the oxidative stability indices (Oxidative Onset Temperature or OOT and Oxidative Induction Time or ΟΙΤ) at the end of each extrusion cycle. According to the results, by the end of the fifth extrusion cycle, the MFR index of the examined material had not changed as much as that of the non-stabilized material, but it was stabilized around 12.0 g/10min, respectively. Moreover, the OOT and OIT had increased by 9.0°C and 3.5 min respectively, compared to the ones of the corresponding specimens of the non-stabilized material. Thus, the results of the assessment methods confirmed the successful protection and stabilization against thermomechanical and oxidative distress of the tested PCR polypropylene during the reprocessing.	el
heal.advisorName	Βουγιούκα, Σταματίνα	el
heal.committeeMemberName	Δέτση, Αναστασία	el
heal.committeeMemberName	Παπαδόπουλος, Γεώργιος	el
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Χημικών Μηχανικών. Τομέας Σύνθεσης και Ανάπτυξης Βιομηχανικών Διαδικασιών (IV). Εργαστήριο Τεχνολογίας Πολυμερών	el
heal.academicPublisherID	ntua	el
heal.numberOfPages	160 σ.	el
heal.fullTextAvailability	false