Structure design and determination of curing kinetics for epoxy based functional hybrid materials

U ovoj doktorskoj disertaciji je ispitan uticaj montmorilonita i termoplastičnih segmentiranih poliuretana na kinetiku reakcija umrežavanja, strukturu i svojstva funkcionalnih hibridnih materijala na osnovu epoksidnih smola. Pripremljene su dve serije uzoraka hibridnih materijala: prva na osnovu epoksidne smole sa različitim sadržajem organski modifikovanog montmorilonita (0, 1, 3, 5 i 10 mas.%) umrežene sa umreživačem Jeffamine D-230; druga serija je sintetisana na osnovu epoksidne smole, sa različitim sadržajem (10, 15 i 20 mas.%) termoplastičnog poliuretanskog elastomera sa različitim sadržajem tvrdih segmenata (20, 25 i 30 mas.%) sintetisanih na osnovu alifatičnog polikarbonatnog diola i heksametilendiizocijanata i produživača lanca butandiola, kao i katalizatora dibutiltin dilaurata; kao i bez dodatog elastomera umrežene sa diaminom Jeffamine D-2000. Umrežavanje reaktivnih sistema sa projektovanim sirovinskim sastavom je praćeno diferencijalnom skenirajućom kalorimetrijom (DSC). Modeli izokonverzije primenjeni su da se ustanovi da li dodatak punila utiče na reakciju umrežavanja hibridnih materijala. Sintetisani materijali su analizirani dinamičkomehaničkom analizom (DMA), mikroskopijom atomskih sila (AFM), kao i TG-DSC i TG-MS metodama i određena su mehanička svojstva (zatezna čvrstoća, prekidno izduženje i tvrdoća po Šoru A). Epoksidni materijal sa 10 mas.% organski modifikovanog montmorilonita ima značajno niže vrednosti energija aktivacije za definisane stepene reagovanja, čime je potvrđen katalitički efekat gline sa slojevitom strukturom kada je prisutna u reakcionoj smeši u dovoljnoj količini. Uticaj otežane difuzije pri kraju reakcije je izraženiji u prisustvu montmorilonita, čime je pokazano da njegovo prisustvo utiče na ceo mehanizam umrežavanja. Utvrđeno je da na vrednosti G', pored udela montmorilonita, utiče i stepen dispergovanja čestica unutar polimerne matrice. Zaključeno je da dodatak punila do 3 mas. % utiče povoljno na ispitana mehanička svojstva, dok pri sadržaju od 5 i 10 mas. % dolazi do aglomeracije čestica punila, što negativno utiče na ispitana svojstva, osim tvrdoće, koja se povećava linearno sa dodatkom punila montmorilonita. Na osnovu rezultata TG analize zaključeno je da je sa porastom udela montmorilonita u epoksidnoj matrici termička stabilnost uzoraka ispitivanih u atmosferi vazduha neznatno poboljšana, dok u inertnoj atmosferi nema uticaja na termičku stabilnost, niti na mehanizam raspada hibridnih materijala na osnovu epoksidnih smola sa različitim udelima montmorilonita. Kod sistema kod kojih je dodavan termoplastični poliuretanski elastomer, zaključeno je da pri većem sadržaju segmentiranih poliuretana u epoksidnoj matrici (10 i 15 mas.%) proces umrežavanja započinje na nižim temperaturama i maksimalna brzina se ostvaruje na nižim temperaturama, a najveća vrednost promena ukupne entalpije reakcije umrežavanja je određena za hibridni materijal sa poliuretanom koji u svojoj strukturi ima 30 mas.% tvrdih segmenata. Zatezna čvrstoća hibridnih materijala raste sa porastom udela tvrdih segmenata u strukturi poliuretana, kao i sa porastom masenog udela poliuretanskog elastomera u epoksidnoj matrici. Dodatkom termoplastičnih segmentiranih poliuretana značajno je povećano prekidno izduženje epoksidnih smola. Sa porastom udela tvrdih segmenata kod poliuretana dodatih u istom masenom procentu u epoksidnu matricu, tvrdoća raste. Ustanovljeno je da na konačna svojstva hibridnih materijala utiče izbor polaznih komponenti, način umešavanja punila u matricu i uslovi pri kojima se vrši umrežavanje. Zaključeno je da je dobro poznavanje kinetičkih parametara reakcije umrežavanja važno za pravilan odabir optimalnih uslova za proizvodnju i preradu hibridnih materijala u industrijskim uslovima.In this thesis the influence of clay fillers and thermoplastic segmented polyurethanes on the curing kinetics, structure and properties of functional hybrid materials based on epoxy resins was assessed. Two sets of hybrid material samples were prepared. First type of samples was based on epoxy resin with a different content of organically modified montmorillonite (0, 1, 3, 5 and 10 wt. %) and crosslinking with hardener Jeffamine D-230. Second type of samples was based on epoxy resin, having different content (10, 15 and 20 wt. %) of thermoplastic segmented polyurethane with different content of hard segments (20, 25 and 30 wt. %) based on aliphatic polycarbonate macrodiols and hexamethylene diisocyanate, with chain extender 1,4-butanediol and the catalyst, dibutyltin dilaurate, and also a sample without added elastomeric polyurethane and crosslinking with hardener Jeffamine D- 2000. The curing of the hybrid materials based on epoxy resins systems were investigated by non-isothermal differential scanning calorimetry (DSC). The kinetic study by isoconversion models has been carried out using data from DSC. The synthesized materials were analyzed by dynamicmechanical analysis (DMA), atomic force microscopy (AFM) as well as TG-DSC and TG-MS methods and mechanical properties (tensile strength, elongation and hardness at Shore A) were determined. Epoxy based hybrid material with 10 wt. % of the organically modified montmorillonite has significantly lower activation energy values for the defined reaction rates, thereby confirming the catalytic effect of the clay with the layered structure when present in the reaction mixture in sufficient quantity. The diffusion effects at the end of the reaction are more pronounced in the presence of montmorillonite, which indicates that its presence affects the entire curing mechanism. It was found that G', along with montmorillonite content, is affected by the degree of particle dispersion inside the polymer matrix. It was concluded that the addition of montmorillonite up to 3 wt. % improves investigated mechanical properties, while the samples with 5 and 10 wt. % of montmorillonite resulted in agglomeration of the filler particles, which negatively influenced the investigated properties, except for the hardness which increases linearly with the addition of montmorillonite. TG analysis shows that the increase of montmorillonite content in the epoxy matrix slightly improves the thermal stability in the air, while in the inert atmosphere there is no influence on the thermal stability nor on the mechanism of the decomposition of epoxy based hybrid materials. In the system with a thermoplastic polyurethane filler, it was concluded that hybrid materials with a higher content of segmented polyurethane (10 and 15 wt. %), curing process starts at lower temperatures and the maximum speed is achieved at lower temperatures and the highest value of changes in total enthalpy of the crosslinking reaction is determined for the epoxy hybrid material with polyurethanes containing 30 wt. % of hard segments. Tensile strength of hybrid materials increases with the increase of hard segments content in the polyurethane elastomer as well as with the increase of polyurethane content in the epoxy matrix. The addition of thermoplastic segmented polyurethanes significantly increased the elongation at break of prepared epoxy resins hybrid materials. The increase of the hard segments content in polyurethane, in the same ratio, improves hardness of epoxy based hybrid material. It was concluded that the final properties of hybrid materials are influenced by the selection of initial compounds, methods of processing and the curing conditions. It was concluded, as well that knowing the kinetic parameters of curing reaction is important for the proper selection of optimal parameters for production and processing of hybrid materials in industrial conditions

Fourier-trasform infrared spectroscopy spectra database validation for microplastics identification

Mikroplastika, koja zbog malih dimenzija i male gustine lako dospeva do svih delova Zemlje, je zaokupila pažnju naučne zajednice u poslednjoj deceniji. Najveća pažnja, posvećena je uticaju, kao načinima unošenjana u ljudski organizam. Jedini način za sprečavanje ulaska mikroplastike u lanac ishrane je poštovanje principa cirkularne ekonomije. Postoji veliki broj različitih čestica mikroplastike u odnosu na vrstu polimera iz kojih su dobijene. Kako bi se analiziralo poreklo čestica mikroplastike, neophodno ih je prvo izolovati, a zatim identifikovati. Neke od metoda za identifikaciju mikroplastike su Infracrvena spektroskopija sa Furijeovom transformacijom (FTIR), Raman spektroskopija, pirolitička gasna hromatrografija – masena spektroskopija, od kojih su FTIR i RAMAN nedestruktivne metode. U radu je ispitan granulat 9 najčešće korišćenih komercijalnih polimera u izvornom obliku. Urađena je FTIR analiza, a dobijeni rezultati poznatih polimera upoređeni su sa bazom podataka uređaja. Utvrđen je stepen podudaranja sa pronađenim polimerom. Dobijeni rezultati su validirani u odnosu na deklarisane polimere. Na osnovu dobijenih rezultata data su uputstva za dalju interpretaciju rezultata FTIR-a prilikom identifikacije mikroplastike, kao i predlozi za buduća istraživanja.Microplastics have captured the attention of the scientific community in the last decade. Due to small dimensions and low density, they can easily reach all parts of the Earth. Lately, the attention is shifted towards the health effects, and the pathways of entering into the human organism. The only way to prevent microplastics from entering the food chain is to respect the principles of circular economy. There are many different types of microplastic particles regarding the polymer from which they are obtained. In order to analyse the origin of microplastic particles, firstly it is necessary to isolate them, and then identify them. Some of the methods for identifying microplastics are Fourier-Transform Infrared Spectroscopy (FTIR), Raman spectroscopy, pyrolytic gas chromatography - mass spectroscopy, of which FTIR and RAMAN are non-destructive methods. This paper investigates beads of 9 most commonly used commercial polymers in their virgin form. FTIR analysis was performed, and the obtained results of known polymers were compared with the device database. The degree of matching with the found polymer was determined. The obtained results were validated in relation to the declared polymers. Based on the obtained results, instructions are given for further interpretation of FTIR results during the identification of microplastics, as well as suggestions for future research

The necessity for monitoring of microplastics in Serbia

Microplastics are silent pollutants present in the almost every corner of the planet, even the most isolated. European legislative has recognized the necessity for the monitoring of microparticles, which involves the establishment of monitoring programmes, enabling the assessment of the status of marine waters on a regular basis. Serbia continuously adopts and harmonizes laws and regulations with the regulations of the European Union (EU). Unfortunately, microplastics is not yet the subject of our Regulations. Main source of pollution of oceans with microplastics are rivers, therefore it is necessary to estimate river microplastic emissions to the world's oceans. Microplastics find the way to rivers, mostly from the waste waters from washing machines. Serbia is country with long network of freshwaters, including the second largest river in Europe – Danube. River that flows through many industrial cities, and carries great industrial and communal burden. By detail analysis of Serbian legislative, it was found that no law or regulative considers microplastics as pollutant. Therefore, the monitoring of microplastics is not obligatory. We consider that it is time that Serbia finally recognizes this environmental problem, and includes it in the existing legal framework. We propose that the microplastics in sewage waters are monitored on the regular basis, including tap and bottled waters, to see if there is contamination with microplastics. This information will contribute to establishment of monitoring programmes in Serbia and thus prevent further microplastic pollution

Bioremediation of soil polluted with oil

Microplastics have reached all corners of our planet, including soil and water. Plastic-degrading bacteria are seen as a promising, environmentally friendly tool for the bioremediation of soil polluted with microplastics. The petroleum origin of plastics makes them candidates for bioremediation analogous to the bioremediation of soil polluted with oil and its derivatives. A mud pit, located near the village of Turija, used for mud formation for the lubrication of drill pipes for drilling rigs, ended up polluted with oil and its derivatives. It was bioremediated using the in situ procedure. The content of n-hexane extractable substance, total petroleum hydrocarbon, dry substance, and loss on ignition were analyzed.Микропластика се може наћи у сваком кутку наше планете, укључујући земљиште и водене површине. Сматра се да су бактерије које разграђују пластику будућност еколошки прихватљиве биоремедијације земљишта загађеног микропластиком. Због нафтног порекла, постоји оправдана сумња да се поступак биоремедијације земљишта загађеног нафтом и дериватима нафте адекватним избором микроорганизама може применити и код биоремедијације земљишта загађеног микропластиком. Исплачна јама у близини села Турија, која се користила за прављење исплаке за цеви за бушење нафтних бушотина, након завршетка бушотине, била је загађена нафтом и дериватима. Извршена је биоремедијација ин ситу поступком. Одређен је садржај супстанци растворних у хексану, укупних нафтних угљоводоника, суве супстанце и губитка при жарењу, непосредно пре и 90 и 180 дана након поступка биоремедијације

A Brief Bibliometric Analysis of Microplastic and Nanoplastic Particles in Food

Microplastic and nanoplastic particles have gained significant attention in recent years due to their potential presence in various environmental matrices, including food. This bibliometric analysis aims to explore the scientific landscape surrounding the study of microplastic and nanoplastic particles in food, shedding light on key research trends, prominent authors, and notable journals in this field. To conduct this analysis, a comprehensive search was performed on scholarly databases, including Web of Science, PubMed, and Scopus, using relevant keywords such as “microplastic”, “nanoplastic”, “food”, and related terms. The analysis focused on peer-reviewed articles published between 2020 and 2023. The search found 313 articles on microplastic and nanoplastic particles in food, indicating a growing interest in this research area. The number of publications showed an upward trend, with the most productive year being 2020 (38% of papers), followed by 2023 and 2021 (23% each). In 2020, 16% of papers were published. Among the analyzed articles, 48% were original research papers, 46% were reviews, and the remaining 6% included book chapters, perspectives, and other publications. The analysis revealed that the most prolific authors in this field include researchers such as Jansen, M.A.K., Abbasi, S., and Banerjee, A., who have significantly contributed to the study of microplastics and nanoplastics in food. Additionally, several collaborations between different research institutions were observed, emphasizing the multidisciplinary nature of this research area. Furthermore, the analysis identified key journals publishing research on microplastics and nanoplastics in food, including Science of the Total Environment, the Journal of Hazardous Materials, and Environmental Pollution. The increasing number of publications on microplastic and nanoplastic particles in food indicates the growing awareness and concern regarding the potential risks associated with these contaminants. This bibliometric analysis provides insights into the scientific landscape of microplastic and nanoplastic particles in food. The analysis demonstrates the upward trajectory of research in this field, identifies influential authors, and highlights the significant role of specific journals. Continued research and collaboration are essential to further our understanding of the impacts of microplastics and nanoplastics on food safety and human health, facilitating the development of effective mitigation strategies.Proceedings of The 14th European Nutrition Conference FENS 2023, Belgrade, Serbia, 14–17 November 202

Legal framework and possibilities for regulation of microplastics content in waters in Serbia

Ne postoji deo planete do koga nije došla mikroplastika. Uticaj mikroplastike na čoveka se još uvek ispituje. Ali dokazano je da se lancem ishrane unosi u organizam. Mikroplastika je do sada pronađena u brojnim namirnicama za ljudsku ishranu. Osim toga, izaziva promene u biodiverzitetu. Reke Srbije se ulivaju u tri morska sliva čime direktno utiču na zagađenje tih mora. Stoga je važno da se Srbija uključi u borbu protiv mikroplastike. Zakonodavstvo EU je prepoznalo problem mikroplastike. Iako Srbija usklađuje zakone i propise sa propisima Evropske unije, nijedan zakon niti drugi propis ne smatra mikroplastiku zagađivačem. Pošto je mikroplastika globalni problem, za njegovo rešavanje neophodno je udružiti snage, i zajedničkim delovanjem države, nevladinog sektora, naučne zajednice, pojedinaca, ali u najvećoj meri i samih kompanija krenuti u akciju.There is no part of the planet that has not been contaminated with microplastics. The impact of microplastics on humans is still being investigated. But it has been proven that it is taken into the body through the food chain. Microplastics have so far been found in a number of foods for human consumption. In addition, it causes changes in biodiversity. The rivers of Serbia flow into three sea basins, which directly affects the pollution of those seas. Therefore, it is important for Serbia to get involved in the fight against microplastics. EU legislation has recognized the problem of microplastics. Although Serbia harmonizes laws and regulations with the regulations of the European Union (EU), no law or other regulation considers microplastics as a pollutant. Since microplastics is a global problem, in order to solve it, it is necessary to join forces, and by joint action of the Government, the scientific community, individuals, but mostly of the companies themselves, to take action

Supercritical fluids as green solvents

Supercritical fluids(SCFs) offer the possibility for obtaining and designing of new environmentally friendly and sustainable products with special characteristics. Recently, SCFs have been applied for polymer processing,polymer extraction and purification, preparation of optical materials, supercritical blending of additives into polymers,as a foaming agent for microcellular materials, impregnation, fractionation, purification and formation of powdered polymers. This review is focused on some applications of supercritical fluids with special emphasis on their properties of supercritical fluids in water and carbon-dioxide green industrial chemical processes

Microbial bioremediation of residual heavy oil waste from power plants (Serbia) and its reuse: example of circular economy

In this study the ex-situ bioremediation of waste heavy residual oil fuel was examined. Microbial consortium was isolated from the polluted site at Belgrade Heating Plants (Serbia) and was added to the projected biopile. The nutrients, aeration-periodic mixing was used during process. The biopile was inoculated and biostimulated for 150 days. As a result, the total petroleum hydrocarbons (TPH) decreased by approximately 80 times. Also, the content of humic acids increased which indicated the beginning of pedogenesis phase – soil formation (soilification). Level of humic acids during process at the end is higher about 40%. Also, bioremediation microorganisms from the inorganic matrix (river sand) generate clay minerals (content increases by about 50%) which are characteristic of the soil. At the same time, due to the microbial generation of organic acids, the concentration of carbonate minerals from sand (calcite and dolomite) decreases. All these indicators confirm the efficiency of bioremediation and the simultaneous formation of man-made soil (MMS) as new resource for agriculture, landscaping and reforestation. The obtained soil was used for the stabilization of municipal waste as an overlay at this time. In conclusion: bioremediation that generates some useful geo-material is a great example of a circular economy that is different from the usual ones (such as aluminum can and paper recycling).Poster: [https://cer.ihtm.bg.ac.rs/handle/123456789/5411

Microbial bioremediation of residual heavy oil waste from power plants (Serbia) and its reuse: example of circular economy

Poster presented at: The 24th International Biohydrometallurgy Symposium (IBS) 20/11 2022Abstract: [https://cer.ihtm.bg.ac.rs/handle/123456789/5410

Gamma irradiation ageing study of elastomers based on ethylene/propylene/5-ethylidene-2-norbornene rubber

V International Conference on Radiation in Various Fields of Research : RAD 2017 : book of abstracts; June 12-16, 2017; Budva, Montenegr