Functionalization of aluminium oxide for composites based on unsaturated polyester resins synthesized from waste poly(ethylene terephthalate)

Abstract

Cilj ove doktorske disertacije je ispitivanje fizičkih i hemijskih svojstava kompozita na bazi nezasićene smole poliestera (NZPE) sintetisanoj od proizvoda katalitičke depolimerizacije poli (etilen tereftalata) (PET) u višku od 1,2-propilena glikol (PG) sa ojačanjem od nano/mikro čestica alumine. Korišćena su dva tipa alumine: komercijalna (cAl2O3) i sintetizovana dopirana sa Fe (Fe-Al2O3). Da bi dodatno poboljšali gore navedena svojstva NZPE smole, čestice alumine su modifikovane sledećim silanima: Viniltris (2- metoksietoksi)silan (VTMOEO), 3-metakriloksipropil-trimetoksisilan (MEMO) i 3- (aminopropil) trimetoksizilan (APTMS) kao metil estri masnih kiselina lanenog ulja (biodizel - BD). Ispitan je uticaj veličine čestica i udela netretiranih/modifikovanih čestica alumine na mehanička, dinamičko-mehanička i termička svojstva dobijenih kompozita. Sintetisana NZPE smola kvalitativno je okarakterisana korišćenjem NMR i FTIR tehnika, dok su čestice alumine ispitivane uz pomoć XRD, FTIR, SEM i analizom slike kako bi se dobile njihove morfološke karakteristike. Najbolja zatezna čvrstoća postignuta je udelom 1 mas% VTMOEO modifikovanog Fe-Al2O3 u poređenju sa čistom NZPE smolom, dok je mikro Vickers tvrdoća značajno poboljšana u svim analiziranim uzorcima. Rezultati DMA pokazali su značajan uticaj ugradnje čestica alumine u NZPE matricu. Primećeno je da Fe-Al2O3 glinica poseduje veću toplotnu stabilnost u poređenju sa c-Al2O3. Trodimenzionalno orijentisana makroporozna (3DOM) γ-alimina sintetisana je koristeći PMMA kao agens za dobijanje poroznosti konačnog proizvoda. XRD merenja su potvrdila kristalnu fazu γ-alumine, dok su mikro i makro pore potvrđene SEM analizom. Sintetisani adsorbenti su korišćenii za uklanjanje Pb2+, Ni2+ i Cd2+ jona, gde se pokazalo da pH vrednost predstavlja esencijalni parametar za efikasno uklanjanje navedenih polutanata iz vode. Kvalitet adsorpcije je potvrđen modelovanjem izotermi, gde se najadekvatnijim modelom za uklanjanje Pb2+ pokazala Frojndlihova, a za uklanjanje Ni2+ i Cd2+ Dablin-Raduškevičova izoterma. Vrednosti entalpije od 9.59 kJ/mol za Pb2+, 2.45 kJ/mol za Ni2+ i 6.20 kJ/mol for Cd2+ ukazuju na dominantnu fizičku adsorpciju. Kinetički podaci adsorpcije na svim ispitivanim adsorbentima su u dobroj korelaciji sa kinetičkim modelima pseudo drugog reda i Veber-Morrisom, što sugeriše da je adsorpcija difuziono kontrolisana. Izračunate energije aktivacije, Ea, od 4.60 kJ/mol for Ni2+, 0.58 kJ/mol for Cd2+ and 5.71 kJ/mol for Pb2+ dodatno su potvrdile da je adsorpcija navedenih jona na aluminu fizičke prirode. Predstavljeni tehnološki postupci upotrebe otpadnog PET i keramičkog materijala pokazali su mogućnost dobijanja korisnih proizvoda sa dobrim mehaničkim i relativno zadovoljavajućim termičkim karakteristikama. Predstavljena inovativna tehnologija uključuje preradu čvrstog komunalnog otpada, što predstavlja nacionalni interes davanja prednosti ovoj vrsti tehnologije za razvoj/implementaciju zelene i cirkularne ekonomije, kao što je to slučaj u svim razvijenim zemljama

The aim of this doctoral dissertation is investigation of physical and chemical properties of composites based on unsaturated polyester resin (UPR) resin, produced from the product of the catalytic depolymerization of poly(ethylene terephthalate) (PET) in the excess of 1,2- propylene glycol (PG), with the reinforcement of nano-/micro-scaled alumina particles. There were two types of alumina fillers: commercial (c-Al2O3) and synthesized one doped with Fe (Fe-Al2O3). To additionally improve properties of UPR resin, alumina particles were modified by following silanes: Vinyltris(2-methoxyethoxy)-silane (VTMOEO), 3- methacryloxypropyl-trimethoxysilane (MEMO) and 3-(aminopropyl)trimethoxysilane (APTMS) as well as methyl ester of linseed oil fatty acids (biodiesel - BD). The influence of the pristine and modified alumina particles size and loading on the mechanical, dynamicmechanical and thermal properties of the obtained composites was studied. Synthesized UPR resin is qualitatively characterized by NMR and FTIR analysis, while alumina particles were examined by XRD, FTIR, SEM and Image analysis to obtain their morphological characteristics. The best tensile strength was achieved by incorporating the 1 wt% of VTMOEO modified Fe-Al2O3 compared to pure UPR resin, while the micro Vickers hardness was significantly improved in all analyzed samples. The results of DMA showed significant influence of the embedding the alumina particles into UPR matrix. It was remarked that Fe-Al2O3 possessed higher thermal stability in comparison to c-Al2O3. Three-dimensionally ordered macroporous (3DOM) γ-alumina was synthesized using PMMA as porogen agent. XRD measurements confirmed the γ-alumina crystal phase, while SEM confirmed macro and micro porosity. Synthesized adsorbent was used for Pb2+, Ni2+ , and Cd2+ removal, and the results showed that pH is an important parameter which control effectiveness of pollutant removal. The quality of the isotherm modelling of adsorption data was proved by the correlation coefficients and error functions, and the best adsorption model was found to be Freundlich isotherm for Pb2+ removal and Dubinin-Radushkevich isotherm for Ni2+ and Cd2+ removal. The ΔH 0 value of 9.59 kJ/mol for Pb2+, 2.45 kJ/mol for Ni2+ and 6.20 kJ/mol for Cd2+ adsorption onto γ-alumina indicated the dominance of physical adsorption. The kinetic data of the adsorption on all the investigated adsorbents were well fitted with the pseudo-second-order kinetic and Weber-Morris models, suggesting that the rate-limiting step was diffusion rather than chemical sorption. Calculated activation energies, Ea, of 4.60 kJ/mol for Ni2+, 0.58 kJ/mol for Cd2+ and 5.71 kJ/mol for Pb2+ indicate that the adsorption of all three ions onto γ-alumina is a mainly physical adsorption process. The presented technological procedures of waste PET and ceramic material utilization, have shown that they can be used to obtain useful products with good mechanical and relatively satisfactory thermal characteristics. Presented innovative technology involves the processing of municipal solid waste, which represents a national interest in favoring this type of technology for the development/implementation of the green and circular economy, as is the case in all developed countries.