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Laser beam machining (LBM) is used to machine a variety of materials economically and to obtain the required quality metrics. The quality of the surface finish of laser-machined components is affected by the improper selection of process parameters during machining. In this paper, microchannels were machined on Al/TiB2 nanocomposite using an Nd: YAG laser system. An atomic force microscope was used to obtain the surface roughness of microchannels. The aim of this process is to identify the influence of the individual and interactive effect of the process parameters on the surface roughness of the microchannels and to identify the optimum combination of the process parameters for minimum surface roughness. Taguchi’s L9 orthogonal array-based Design of Experiment (DoE) was implemented to conduct the experimental study. A statistical analysis of the results was performed for the experimental data. The results are presented in detail.

The reinforcing and conductive performance of carbon nanotube polymer-based nanocomposites depends on the established network and its configuration. Within this study, we report on the underlying mechanisms of such network formation utilizing single-walled carbon nanotubes (SWCNTs) in low- and high-density polyethylene matrices. Mechanisms were theoretically evaluated through Doi-Edwards theory and experimentally confirmed through plasma etching coupled with electron microscopy as well as rheological flow tests. Results showed that the established network is constructed from SWCNT bundles, which geometrically entangle at a critical volume fraction [phi]v,crit (number of rods: [beta approximately equal to] 30). Below [phi]v,crit, the bundles behave as individual units and may align in the flow direction. Above [phi]v,crit, the rotation of bundles is constrained by neighboring units, leading to a random network configuration. Moreover, the theory successfully explains SWCNT bundle behavior as a Brownian entity and predicts network formation through diminishing thermo- and hydro-dynamically driven diffusion, which can be manipulated during the production to enhance reinforcing/conductive functionality of such materials.

Ultra-high molecular-weight polyethylene (UHMWPE) composites reinforced with Graphene Oxide (GO), Nanodiamonds (ND), and Short Carbon Fibres (SCF) are characterised for their mechanical performance in tensile and short-term creep tests. A methodology to separate and analyse the materials’ viscoelastic (VE) and viscoplastic (VP) responses is applied and evaluated. The results show a clear dependence of the performance on size scale/morphology of the reinforcements. All composites show time-dependent VP responses that can be expressed by Zapas model and fit the experimental data with high accuracy. The analysed VE strains and creep compliance curves reveal the nonlinear stress-dependent VE behaviour of all composites at all tested creep stresses. Combining multiscale reinforcements results in an improvement that surpasses that of individual reinforcements. The results of this work offer valuable input for the design and selection of polymer-based materials in demanding applications where prolonged use under service conditions is critical to their performance.

&nbsp, The aim of the study was to characterize and compare films made of cellulose nanocrystals (CNC), nano-fibrils (CNF), and bacterial nanocellulose (BNC) in combination with chitosan and alginate in terms of applicability for potential food packaging applications. In total, 25 different formulations were made and evaluated, and seven biopolymer films with the best mechanical performance (tensile strength, strain)—alginate, alginate with 5% CNC, chitosan, chitosan with 3% CNC, BNC with and without glycerol, and CNF with glycerol—were selected and investigated regarding morphology (SEM), density, contact angle, surface energy, water absorption, and oxygen and water barrier properties. Studies revealed that polysaccharide-based films with added CNC are the most suitable for packaging purposes, and better dispersing of nanocellulose in chitosan than in alginate was observed. Results showed an increase in hydrophobicity (increase of contact angle and reduced moisture absorption) of chitosan and alginate films with the addition of CNC, and chitosan with 3% CNC had the highest contact angle, 108 ± 2, and 15% lower moisture absorption compared to pure chitosan. Overall, the ability of nanocellulose additives to preserve the structure and function of chitosan and alginate materials in a humid environment was convincingly demonstrated. Barrier properties were improved by combining the biopolymers, and water vapor transmission rate (WVTR) was reduced by 15–45% and oxygen permeability (OTR) up to 45% by adding nanocellulose compared to single biopolymer formulations. It was concluded that with a good oxygen barrier, a water barrier that is comparable to PLA, and good mechanical properties, biopolymer films would be a good alternative to conventional plastic packaging used for ready-to-eat foods with short storage time.&nbsp

U ovom radu istraživan je učinak dodatka višestjenih ugljikovih nanocjevčica (MWCNT) te MWCNT-a modificiranog skupinama COOH (MWCNT-COOH) u rasponu masenih udjela od 0 do 4 % na svojstva termoplastičnog poliuretana (PU). Uzorci nanokompozita pripravljani su postupkom polaganog sušenja iz smjese poliuretana i nanopunila u acetonu pri sobnoj temperaturi. Učinak dodatka nanopunila na sferolitnu morfologiju poliuretana te raspodijeljenost nanopunila u matrici PU analizirana je optičkom polarizacijskom mikroskopijom. Toplinska svojstva u neizotermnim i izotermnim uvjetima istraživana su diferencijalnom pretražnom kalorimetrijom (DSC). Optička polarizacijska mikroskopija pokazala je da dodatak oba punila razrušava krupnu sferolitnu morfologiju poliuretana. Utvrđeno je da je modificirani MWCNT-COOH bolje dispergiran u masi uzorka nego čisti MWCNT. Rezultati DSC-a pokazali su da u neizotermnim uvjetima do određenog udjela dodatak obje vrste MWCNT-a ubrzava kristalizaciju mekog segmenta poliuretana, pri čemu je ubrzanje kristalizacije izraženije u sustavima s punilom MWCNT. Vrijednosti entalpija kristalizacije pokazuju da punilo MWCNT, unatoč lošijoj raspodijeljenosti u masi uzorka, znatnije ometa kristalizaciju mekog segmenta PU-a nego MWCNT-COOH. U uvjetima izotermne kristalizacije punilo MWCNT također znatnije ubrzava kristalizaciju poliuretana nego MWCNT-COOH.

Photocatalysis is a well-known process for the last few decades it is predominantly used for water and air purification, but also for self-cleaning and antibacterial surfaces. The photocatalytic process is one of the advanced oxidation processes, where semiconductors are mainly used as photocatalysts. The most known and used semiconductor is nanosized titania, which can non-selectively decompose organic matters. One of the side effects of nano TiO2 under UV irradiation is photoinduced hydrophilicity, which furthermore improves the self-cleaning effect. The main drawback of TiO2 is that for its activation UV light is needed, which represents only 5 percent of the solar spectrum. Consequently, actinic irradiance power is low and the response of photocatalyst is limited. Novel approaches are being introduced to improve TiO2 response to visible light such as doping, coupling, modification of surface morphology and others. The thesis consists of five principal chapters. The first chapter is focused on a short literature review and explanation of some basic terms and principles that are related to this thesis. The aim of the research was to prepare transparent photocatalytically active thin films on glass and thermosensitive substrates. Four thermosensitive substrates were used: polyvinyl chloride (PVC) foil, polymethyl methacrylate (PMMA) sheet and polyester (PES) fabric coated with a polyvinyl and acrylic coating, with (D1) or without (D2) an additional polyvinylidene fluoride topcoat. The synthesis of films was modified with the introduction of zirconium aiming at improving the photocatalytic activity of the TiO2 films, and the final films had a SiO2 phase present for increased mechanical robustness. The third chapter is dedicated to the experimental part of the thesis. The detailed process of synthesis is described. The sol-gel process was used to prepare initial Ti-Zr sols, colloidal aqueous solutions with TiO2 and ZrO2 nanoparticles derived from titanium and zirconium alkoxides. The four different Ti-Zr sols were prepared with 0, 5, 10 and 20 molar % of Zr according to Ti. The depositing solution was prepared by mixing Ti-Zr sol, SiO2 sol binder, 1-propanol and 2-propoxyethanol, and then thin films were deposited by dip-coating technique. After the deposition, samples did not require high-temperature calcination since the photocatalytic anatase phase was present already after drying the deposited layers. Coated glass slides were put into a furnace at 150 °C, while samples on thermosensitive substrates were just treated by a heat gun. Samples in powder and thin film form were characterized by UV-Vis, FTIR-ATR and laser beam deflection spectroscopy, X-ray diffraction, scanning electron microscopy and thermal analysis. One of the main aspects of the photocatalyst is its activity. Photocatalytic activity of the thin films was determined, either quantitatively by the formation of fluorescent hydroxyterephthalic acid, one of the first degradation products of terephthalic acid deposit, or qualitatively by a visual-based method where degradation of resazurin ink was observed. Two additional methods were used on glass samples, electron paramagnetic resonance, and degradation of methyl stearate by observing the change in water contact angle under UVA irradiation. Mechanical stability of films on various substrates is an essential factor, describing how successful was immobilization of the photocatalytic materials on the substrate. It was determined by the pencil hardness test, i.e., Wolff-Wilborn method. In the fourth chapter, titled “Results and Discussion,” the most important part of the thesis is placed. Materials characterization and associated discussion of the results are divided into three major parts: i) powder samples characterization ii) characterization of thin films on a glass substrate, and iii) characterization of films on thermosensitive substrates. In the conclusions, the main findings of the Ph.D. research work are summarized. One of our initial hypotheses was disapproved, thin films were not more active with a higher content of zirconium. However, they were more durable. All the obtained films were transparent and photoactive, despite the low-temperature synthesis procedure. Besides commonly used glass substrate, immobilization on thermosensitive substrates was also successful. Fotokataliza je postala v zadnjih nekaj desetletjih zelo razširjena uporablja se predvsem za čiščenje vode in zraka, za samočistilne ter protibakterijske površine. Fotokatalitski proces spada med napredne oksidacijske procese in kot fotokatalizatorji so največkrat uporabljeni polprevodniki. Najbolj znan in najpogosteje uporabljen polprevodnik je (nano) titanov dioksid, ki lahko neselektivno razgradi organske snovi ob UV sevanju. Pri obsevanju TiO2 z UV svetlobo se pojavi tudi fotovzbujena hidrofilnost, ki še dodatno izboljša samočistilni učinek. Ena od glavnih pomanjkljivosti TiO2 je, da se za njegovo fotoaktivacijo uporablja UV svetloba, ki predstavlja le pet odstotkov sončnega spektra. Za boljši odziv TiO2 na vidno svetlobo se razvijajo novi postopki, na primer dopiranje, kombiniranje z drugimi polprevodniki, modifikacija morfologije površine itd. Doktorsko delo ima pet glavnih poglavij. Prvo poglavje je osredotočeno na krajši pregled obstoječe literature in razlago nekaterih osnovnih pojmov. V drugem poglavju je predstavljen namen doktorskega dela. Pripravila sem transparentne fotoaktivne tanke plasti na steklu in temperaturno občutljivih podlagah. Izbrala sem štiri različne občutljive podlage: polivinil kloridna (PVC) folija, polimetil metakrilat (PMMA) plošča in poliesterska (PES) tkanina, prevlečena s slojem polivinila in akrila z (D1) ali brez (D2) dodatne poliviniliden fluoridne (PVDF) prevleke. Postopek priprave filmov smo obogatili z vpeljavo cirkonija, tako naj bi izboljšali aktivnost samih TiO2 filmov, končni raztopini je bil dodan tudi SiO2, ki je izboljšal mehanske lastnosti filmov. Tretje poglavje je posvečeno eksperimentalnemu delu. V poglavju je opisan podroben proces sinteze tankih plasti. Sol-gel postopek sem uporabila za pripravo začetnih Ti-Zr solov izhajajoč iz titanovega in cirkonijevega alkoksida. Pripravila sem štiri različne Ti-Zr sole z 0, 5, 10 in 20 množinskimi % cirkonija glede na titan. Raztopine za nanašanje so vsebovale Ti-Zr sol, SiO2 vezivo, 1-propanol in 2-propoksietanol tanke plasti pa so bile nanešene s tehniko potapljanja. Tanke filme po nanosu ni bilo potrebno termično obdelati na visoki temperaturi, ker je fotoaktivna anatazna faza že prisotna po sušenju vzorcev. Tako so bili vzorci na steklu toplotno obdelani v peči pri 150 ° C, vzorce na termično neobstojnih podlagah pa sem utrdila zgolj s toplotno pištolo. Praškaste vzorce in tanke plasti smo karakterizirali z naslednjimi metodami: UV-Vis, FTIR-ATR spektroskopijo in spektroskopijo z odklonom laserskega žarka, rentgensko praškovno difrakcijo, presevno elektronsko mikroskopijo in termično analizo. Najpomembnejša lastnost fotokatalizatorja je fotoaktivnost, ta je bila določena na tankih plasteh z dvema različnima metodama kvantitativno z merjenjem koncentracije hidroksiteraftalne kisline po razgradnji teraftalne kisline in kvalitativno, z opazovanjem razgradnje barvila resazurin. Z dvema dodatnima metodama smo izmerili fotoaktivnost tankih plasti na stekleni podlagi, z elektronsko paramagnetno resonanco in z merjenjem kontaktnega kota po razgradnji metil stearata pri UV obsevanju. Zelo pomembna lastnost tankih plati je mehanska odpornost in z merjenjem le te lahko ocenimo, če je bila imobilizacija na podlago uspešna. Mehansko stabilnost filmov smo določili z Wolff-Wilborn-ovo metodo. V četrtem poglavju je opisana karakterizacija materialov s spremljajočo razpravo o rezultatih, ki je razdeljena na tri glavne dele: i) karakterizacija praškastih vzorcev ii) karakterizacija tankih plasti na stekleni podlagi in iii) karakterizacija tankih plasti na termično neobstojnih podlagah. V zaključku so povzete glavne ugotovitve. Ena od naših začetnih hipotez ni bila potrjena, saj tanke plasti z višjo vsebnostjo cirkonija niso bile aktivnejše, izkazovali pa so večjo mehansko odpornost. Vsi vzorci so bili, kljub nizki temperaturi pripravi, transparentni in fotoaktivni. Imobilizacija fotokatalizatorjev je bila uspešna na steklu kot tudi na termično neobstojnih podlagah.

The mesh formation of single-walled carbon nanotube (SWCNT) superstructure, i.e. nano-mesh, in low- and high-density polyethylene (LDPE and HDPE) matrices was observed by using plasma etching technique and SEM analysis. Nano-mesh was established by two mechanisms: i) alignment of SWCNT bundles (forming network backbone) and ii) shish-kebab induced crystallization (forming network net). The network was formed at low SWCNT content due to the high aspect ratio of nano-filler, which additionally contributed to alignment. Established nano-mesh superstructure caused confinement effect disrupting crystallization and melting kinetics, which directly affected mechanical properties. Although mechanical properties of LDPE and HDPE nanocomposites profoundly improved, i.e. Young’s modulus increased for 230% and 30%, respectively, at only 1 wt% of SWCNTs, HDPE nanocomposites showed visible confinement that reduced effective reinforcement. It seems that HDPE nanocomposites cannot achieve full reinforcing potential since confinement effect restricts the crystal growth, which gradually reduces effective reinforcement in semi-dilute regime.

U ovom radu istraživan je učinak dodatka višestjenih ugljikovih nanocjevčica (MWCNT) te MWCNT-a modificiranog skupinama COOH (MWCNT-COOH) u rasponu masenih udjela od 0 do 4 % na svojstva poliuretana. Uzorci nanokompozita pripravljani su dispergiranjem nanopunila u otopini poliuretana u acetonu te polaganim isparavanjem otapala pri sobnoj temperaturi. Utjecaj punila na mehanička svojstva kompozita ispitan je testom jednoosnog istezanja, a električna provodnost uzoraka određivana je metodom četiri kontakta. Toplinska postojanost istražena je termogravimetrijskom analizom (TGA). Obje vrste punila MWCNT povećavaju modul, ali snižavaju prekidnu čvrstoću i prekidno istezanje kompozita. Rezultati ispitivanja električne provodnosti pokazali su da se, u odnosu na čisti PU koji ima provodnost reda veličine 10–13 S cm–1, provodnost nanokompozita s masenim udjelom punila MWCNT 0,2 % znatno povećava na vrijednost reda veličine 10–6 S cm–1. Daljnjim povećanjem do masenog udjela obje vrste MWCNT-a 4 %, provodnost se dalje povećava do vrijednosti većih od 10–2 S cm–1. Taj učinak povećanja provodnosti neznatno je jače izražen u sustavima s MWCNT-COOH-om. Rezultati termogravimetrijske analize upućuju na to da se dodatkom obje vrste MWCNT-a znatno poboljšava toplinsku postojanost u istraživanom rasponu udjela nanopunila, pri čemu je ovaj učinak nešto izraženiji za sustave s punilom MWCNT. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna., In this paper, the influence of multiwalled carbon nanotubes (MWCNT) and carbon nanotubes modified with COOH groups (MWCNT-COOH) on the mechanical and electrical properties as well as on thermal stability of polyurethane (PU) were investigated. The samples of nanocomposite were prepared by dispersion of the nanofiller in a solution of polyurethane in acetone, followed by slow evaporation of the solvent at room temperature. The effect of the fillers on the mechanical properties of PU nanocomposites was examined by the uniaxial deformation test, and electrical properties of the samples were determined by the four probe method. Thermal stability was investigated by thermogravimetric analysis (TGA). The addition of both types of MWCNTs fillers increases modulus (Fig. 1), due to higher modulus of the nanofillers. Due to the better distribution in PU matrix and stronger interactions between COOH groups and carbonyl group in PU matrix, nanocomposites with MWCNT-COOH have higher modulus than nanocomposites with MWCNT filler. Most of the composites have lower strength and elongation at break than PU (Figs. 2 and 3). Smaller MWCNT-COOH aggregates and stronger interactions between this filler and the PU matrix cause less pronounced decreasing of strength at break. Compared to the pure PU, with conductivity of the order of 10–13 S cm–1, the conductivity of the nanocomposite with mass fraction of MWCNT nanofiller 0.2 % substantially increases up to the value of the order 10–6 S cm–1 (Fig. 4). A further increase up to 4 % for both types of MWCNTs, resulted in a further increase in conductivity up to values exceeding 10–2 S cm–1. Due to the better distribution in PU matrix and stronger interactions between COOH groups and carbonyl groups in PU matrix, the conductivity increase effect in systems with MWCNTs-COOH is slightly more pronounced. All investigated nanocomposites have potential applications as electric discharge materials and for electrostatic painting. The results of the thermogravimetric analysis indicate that the addition of both types of MWCNTs significantly improves the thermal stability (Figs. 6 and 7). The maximal degradation rate temperature of polyurethane increased by about 45 °C, thereby this effect is slightly more pronounced for systems with MWCNTs (Fig. 7). This work is licensed under a Creative Commons Attribution 4.0 International License.

The properties of polymer nanocomposites exceed the properties of common composite materials due to the nanoscale size and morphology of the fillers used. Particulate fillersare commonly used in polymers forimproved mechanical and thermal properties, as well as modified electrical properties and cost reduction. Organically modified layered clays, such asmontmorillonite, are among the most widely used fillers for the improvement of polymer matrices. Presented in this review are some of the most studied clay nanocomposites including clay-polyolefin, clay-polyester and clay-thermoplastic polyurethanenanocomposites. Additionally, the properties of clay-biopolymers nanocomposites will also be discussed. Svojstva polimernih nanokompozita prevazilaze svojstva uobičajenih kompozitnih materijala zbog nanodimenzija i morfologije upotrebljenih punioca. Čestični punioci se uglavnom koriste u cilju poboljšnja mehaničkih i toplotnih svojstava polimera, kao i za modifikovanje električnih svojstava polimerne matrice i smanjenja cene koštanja. Organski modifikovane slojevite gline, kao što je montmorilonit, su između ostalih, najzastupljeniji punioci u upotrebi za poboljšanje svojstava polimernih matrica. Ovim preglednim radom biće prikazani najznačajniji i najviše proučavani glina-polimerni nanokompoziti, kao što su glina-poliolefini, glina-poliestar i glina-termoplastični poliuretan nanokompoziti. Takođe, svojstva biopolimer-glina nanokompozita biće predstavljena i razmatrana u radu.

Two types of innovative coatings based on fluoroethylene/vinylether alternating copolymers are investigated as protective systems for bronze works-of-art. The influence of a polyhedral oligomeric silsesquioxane (POSS), i.e. open-cube trisilanol-heptaisooctyl-POSS, on the surface, mechanical, optical and electrochemical properties of coatings is examined. It is found that the isooctyl groups in the organic shell of POSS cause an increase in the hydrophobicity of the surface. On the other hand, nanoindentation tests show that the reduced modulus, hardness and plasticity index decrease with the addition of POSS, while abrasion resistance is slightly improved. Haze of coatings increases when POSS nanoparticles are present. More importantly, a beneficial effect of POSS addition on the protective efficiency against corrosion is assessed by exposure of coatings to acidic vapours and electrochemical treatments. In this regard, potentiodynamic polarisation clearly shows that the protective efficiency is systematically larger for coatings comprising POSS. The ex situ IR reflection-absorption spectroelectrochemistry shows that cuprous oxide can eventually form at the coating|bronze interface, which is identified through the spectroelectrochemistry of unprotected bronze. Keywords: Bronze, Protective coating, Nanocomposite, Fluoropolymer, POSS nanoparticle, Nanoindentation

In this paper, the preparation and characterisation of polymer materials suitable for single point incremental forming (SPIF) technology were performed. Three different kinds of mixtures were selected: a mixture of neat polyamide 12 (PA12), a nanocomposite with PA12 matrix and 1% clay (Cloisite 93A), and a nanocomposite with PA12 matrix and 3% clay (Cloisite 93A). Materials were produced using a melt intercalation method followed by compression moulding. According to the needs of SPIF technology, morphological and mechanical properties were investigated in the obtained mixtures. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to characterize morphological properties. It was determined that the most desired obtained exfoliated structure of clay in the polymer matrix was achieved. Static tensile testing and dynamic mechanical analysis as well as the determination of glass transition temperature and crystallinity of all analysed materials were used to obtain mechanical and thermal properties of the mixtures. The results obtained for each mixture were compared with respect to the content of clay. The content of clay (Cloisite 93A) showed a strong influence on the properties of the obtained materials. The presence of clay (Cloisite 93A) affected the increase of tensile strength and Young's modulus, while its influence on the attained elongation was not unique., Ministry of Education, Youth and Sports of the Czech Republic (Program NPU I) [LO1504]; Slovenian Research AgencySlovenian Research Agency - Slovenia [P2-0248]; University of Rijeka [Uniri-tehnic-18-100-589]; Tomas Bata University in Zlin RVOE

Organsko-anorganski hibridni materijali nova su vrsta nanostruktuiranih materijala koji ujedinjuju svojstva obiju faza od kojih se sastoje. Hibridni materijali s polimernom matricom mogu se nazvati i nanokompozitima kod kojih punilo nastaje unutar matrice, što omogućuje mnogo bolji doticaj među fazama. Polietilen tereftalat (PET) nanokompoziti dopirani ugljikovim nanočesticama pripremljeni su uz pomoć ekstrudera kako bi stvorili nanokompozit otporniji na zračenje. Provedena je studija, korištenjem diferencijalnog pretraživanja kalorimetrije (DSC), o strukturalnim promjenama nanokompozita izloženog protonskom zračenju. Pokazano je kako kompozitni materijali koji u sebi sadrže mali udio nanočestica grafena i nanodijamanta, pokazuju bolju strukturalnu stabilnost pri izlaganju radijaciji od čistog polietilen tereftalata. Nanopunila, naročito nanografen zaslužni su za stabilizaciju amorfne faze i povećane kristalnosti očuvajući pritom svojstva polimerne matrice izložene radijaciji. Organic-inorganic hybrid materials are a new class of nanostructured materials, which unite the properties of both their constitutive phases. The polymer matrix hybrid materials can also be considered as nanocomposites where filler is formed inside the matrix, which significantly improves the interphase contact. Poly(ethylene terephthalate) nanocomposites reinforced with a small quantity of carbon nanostructures were prepared by simple melt blending in a twin-screw extruder in order to create polymer nanocomposites for application in high radiation environments. A study of structural modifications introduced by proton beam irradiation was conducted using Differential Scanning of Calorimetry (DSC). It was shown that the composite materials containing a small concentration of nanographen and nanodiamonds exhibit improved structural stability when compared with neat poly(ethylene terephthalate) exposed to proton irradiation under the same irradiation conditions. Nanofillers, particularly nano-graphene platelets stabilized the amorphous phase and increased the crystallinity of polymer matrix exposed to proton irradiation, preserving polymers physical - chemical properties.

Unsaturated polyester resins (UPe) were synthesized from maleic anhydride and products of glycolysis, obtained by polyethylene terephthalate (PET) depolymerization with dipropylene glycol (DPG) in the presence of tetrabutyl titanate catalyst. Waste PET glycolyzed product and UPes were characterized by FTIR and NMR spectroscopy, elemental analysis, acid value (AV), hydroxyl value (HV) and iodine value. Nanocomposites, based on unsaturated polyester resins and hexamethyldisilazane modified silica nanoparticles, were prepared with intention to show one of valuable applicative commercialization of UPe resin. In order to determine potential of the possible implementation of developed new technology for UPe production some aspect of techno- economic analysis was analyzed. Economic potential/benefit and process profitability of the presented technology was based on the use of recycled raw input materials, i.e. waste PET, which is one of the most effective ways to save natural resources, protect the environment, and save money. Principles of green economy was incorporated in the results of developed UPe production technology which is related to both environmental protection and profitability achievement with no additional negative impact to environment, i.e. pollution decrease without negative effect of implemented technology. Nezasićene poliestarske smole (UPe) su sintetisane iz anhidrida maleinske kiseline i proizvoda glikolize, dobijenih depolimerizacijom poli(etilen tereftalata) (PET-a) sa dipropilen-glikolom (DPG) u prisustvu tetrabutil-titanata kao katalizatora. Proizvod glikolize otpadnog PET-a i UPe smole su okarakterisani pomoću FTIR i NMR spektroskopije, elementalne analize, kiselinskog (AV), hidroksilnog (HV) i jodnog broja. Nanokompoziti, bazirani na nezasićenim poliestarskim smolama i nanočesticama silicijum-dioksida modifikovanim heksametildisilazanom, pripremljene su sa namerom da se prikaže jedna od značajnih komercijalnih primena UPe smola. U cilju određivanja mogućnosti mogućih implementacija razvijenih novih tehnologija proizvodnje UPe smola, urađena je neki tehno-ekonomska analiza. Ekonomska korist i profitabilnost procesa prikazane tehnologije su zasnovani na primeni reciklaže sirovog materijala, otpadnog PET-a, što predstavlja jedan od najefektivnijih načina da se očuvaju prirodni resursi, zaštiti životna sredina i uštedi novac. Principi zelene ekonomije su ugrađeni u razvijenoj tehnologiji proizvodnje UPe smola, što se odnosi i na zaštitu životne sredine i dostizanje profitabilnosti bez dodatnih negativnih uticaja na životnu sredinu, odnosno na smanjenje zagađenja bez negativnog uticaja na implementiranu tehnologiju.

Incorporation of inorganic nanoparticles can significantly affect the properties of the polymer matrix. The properties of polymer nanocomposites depend on the type of incorporated nanoparticles, their size and shape, their concentration, and interactions with the polymer matrix. Homogeneity of polymer nanocomposites is influenced very much by the preparation method. In this study, TiO2 nanoparticles surface modified with 6-palmitate ascorbic acid (6-PAA) were encapsulated in poly(methyl methacrylate) (PMMA) by in situ radical polymerization of methyl methacrylate initiated by 2,2'-azobisisobutyronitrile (AIBN). The surface modification of the TiO2 nanoparticles was achieved by the formation of a charge transfer complex between TiO2 nanoparticles and 6-palmitate ascorbic acid. The radical polymerization of MMA in the presence of TiO2-PAA nanoparticles was conducted in solution (PMMA/TiO2-PAA-R), in bulk (PMMA/TiO2-PAA-M) or in suspension (PMMA/TiO2-PAA-S). The main purpose of this study was to investigate the influence of the preparation method on the molar masses and thermal properties of PMMA/TiO2-PAA nanocomposite. It was obtained that molar masses of PMMA extracted from the composites had smaller values compared to molar masses of pure PMMA synthesized in the same manner, which indicated that TiO2-PAA nanoparticles affected the reaction of termination. Thermal properties were investigated by DSC and TGA. The values of glass transition temperature, Tg, were influenced by the way the radical polymerization was conducted, even in the case of the pure PMMA. The Tg of composite samples was always smaller than the value of the corresponding PMMA sample and the smallest value was obtained for PMMA/TiO2-PAA-M since they contained the largest amount of low molar mass residue. The TGA results showed that thermal and thermooxidative stability of polymer composites obtained in solution and in suspension was better than for the pure PMMA obtained in the same way. Predmet ovog rada je dobijanje i karakterizacija nanokompozita kod kojih polimernu matricu čini poli(metil metakrilat) (PMMA), a kao neorgansko punilo nanočestice titan-dioksida. Svi uzorci nanokompozita dobijeni su in situ polimerizacijom preko slobodnih radikala metil metakrilata (MMA) u prisustvu čestica punila. Površinska modifikacija korišćenih nanočestica titan-dioksida izvršena je palmitatom askorbinske kiseline. Uzorci nanokompozita su pripremljeni polimerizacijom metil metakrilata u rastvoru, u masi i suspenzionom polimerizacijom. Određene su vrednosti molarne mase PMMA ekstrahovanog iz kompozitnih uzoraka i dobijeno je da su one manje od vrednosti molarne mase čistog PMMA dobijenog na isti način, na osnovu čega se može zaključiti da nanočestice TiO2-PAA prisutne u toku polimerizacije u sva tri slučaja utiču na reakcije terminacije i dovode do smanjenja molarne mase PMMA matrice. Diferencijalnom skenirajućom kalorimetrijom i termogravimetrijskom analizom utvrđeno je i da način sinteze polimerne matrice i koncentracija čestica punila utiču na termička svojstva dobijenih polimernih nanokompozita.

Cink (II) oksidne mikročestice (300 nm) i nanočestice (100 nm) su sintetizirane u različitim glikolima i kasnije upotrijebljene za pripravu ZnO/poli(metil-metakrilatnih) nanokompozita. Vrlo niske koncentracije dodanog cink-oksida potpuno apsorbiraju UV svjetlo u području od 290 do 380 nm. Osim odlične apsorpcije u UV području, nano cink-oksid bitno poboljšava stabilnost nanokompozita na sunčevu svjetlost kao i na toplinsku postojanost, dok je submikrometarski ZnO manje učinkovit UV apsorber i toplinski stabilizator od nanometarskog ZnO., Zinc (II) oxide micrometer (300 nm) and nano particles (100 nm) were synthesized in different glycols and were used for the preparation of ZnO/poly(methyl methacrylate) nanocomposites. Very low concentrations of zinc oxide quantitatively absorb UV light in the region between 290 and 380 nm. Besides having extraordinary UV absorption properties, nano zinc oxide also substantially enhances the stability towards sunlight as well as thermal stability of resulting nanocomposites. On the other hand, submicrometer ZnO is less effective UV absorber and thermal stabilizer than nano ZnO.

In order to achieve improved mechanical properties of dispersion strengthened nanocomposite, without influencing electrical and thermal conductivity it is necessary for dispersoide to be nano sized and uniformly distributed in base metal matrix. In this paper are presented the results concerning possibility of using UV spectrophotometry for determination of alumina particle size in Cu- AL2O3 system. Presented results show that this method is unefficient as method for determination of dispersoide particle size, due to the coalescence of particles false results are obtained, i.e. particle size significantly higher then one determined by image analysis. Izvod U cilju postizanja poboljšanih mehaničkih osobina disperzno ojačanih nanokompozita, bez uticaja na električnu i termičku provodljivost neophodno je da je dispergovana faza nano veličine i ravnomerno raspoređena u osnovnom metalu. U radu su prikazani rezultati vezani za mogućnost određivanja veličina čestica glinice u nanokompozitnim materijalima iz sistema Cu- AL2O3 primenom UV spektrofotometrije. Dobijeni rezultati pokazuju da je ova metoda nedovoljno pouzdana kao adekvatna metoda za određivanje veličine čestice diperzne faze, jer usled koalescencije čestica dolazi do pojave lažnih rezultata, tj. određena veličina čestica je višestruko veća od veličine određene analizom slike.