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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 aim of this in vitro study was to evaluate cytotoxicity and genotoxicity of six diff erent dental nanocomposite materials, three conventional ones and three fl owable composite resin materials, in human lymphocytes. Th e following materials were tested: Tetric EvoCeram, Tetric Evo-Flow, Filtek Ultimate, Filtek Ultimate Flow, G-aenial and G-aenial Flo. Cytotoxicity was evaluated for two mass concentrations (0.007 g/mL and 0.013 g/mL) of each material, non-cured and cured, after 4 hours and 24 hours. Genotoxicity was evaluated using micronucleus assay under the same conditions as applied during the investigation of cytotoxicity. Uncured forms of Tetric EvoCeram, Tetric EvoFlow and Filtek Ultimate Flow in higher mass concentration caused genotoxic eff ect. Uncured G-aenial Flo in higher mass concentration induced apoptosis and necrosis. Uncured Tetric EvoFlow and uncured Filtek Ultimate Flow in higher mass concentration induced early apoptosis after both test periods. None of the conventional composite resin materials tested showed cytotoxicity except for uncured G-aenial, which induced apoptosis in higher mass concentration in both test periods. In conclusion, under the conditions of this in vitro study, cured conventional composites did not show cytotoxic or genotoxic eff ect, which is important for clinical application of these materials, whereas uncured forms exhibited certain level of cytotoxicity and genotoxicity, mainly because of monomers in their composition., Svrha ovoga istraživanja bila je ispitati in vitro citotoksični i genotoksični učinak šest različitih nanokompozitnih materijala, tri tekuća i tri konvencionalna kompozitna materijala na stanicama ljudskih limfocita. Istraživanje je provedeno na materijalima: Tetric EvoCeram, Tetric EvoFlow, Filtek Ultimate, Filtek Ultimate Flow, G-aenial i G-aenial Flo. Ispitivan je citotoksični učinak dviju masenih koncentracija (0,007 g/mL i 0,013 g/mL) svakog ispitivanog polimeriziranog i nepolimeriziranog materijala nakon 4 sata i 24 sata. Genotoksični učinak je ispitivan primjenom mikronukleus testa u istim uvjetima kao što je učinjeno u ispitivanju citotoksičnog učinka. Nepolimerizirani oblici materijala: Tetric EvoCeram, Tetric EvoFlow i Filtek Ultimate Flow u većoj masenoj koncentraciji pokazali su genotoksični učinak. Nepolimerizirani G-aenial Flo je u većoj masenoj koncentraciji izazvao apoptozu i nekrozu. U oba ispitivana razdoblja nepolimerizirani Tetric EvoFlow i nepolimerizirani Filtek Ultimate Flow su u većoj materijala nije uzrokovao citotoksični učinak osim nepolimeriziranog G-aeniala koji je izazvao apoptozu u većoj masenoj koncentraciji u oba ispitivana razdoblja. Ovo istraživanje provedeno je u in vitro uvjetima. Polimerizirani oblici konvencionalnih kompozitnih materijala nisu pokazali citotoksični i genotoksični učinak koji bi bio važan za kliničku primjenu ovih materijala, dok su nepolimerizirani oblici ukazali na citotoksični i genotoksični učinak uglavnom kao rezultat djelovanja monomera koji se nalaze u sastavu kompozitnih materijala.

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.

Medium-density fi berboards (MDF) were produced, using two different resins of urea-formaldehyde (UF) and phenol-formaldehyde (PF) at 10 % and 8 % contents, respectively. In order to find new source of raw material to satisfy the increasing need of composite manufacturing industry, 10 % of chicken feather was added to the furnish. Moreover, nano-clay was added to investigate its potential improving effects on MDF panel properties. Results showed that panels with PF resin demonstrated significantly lower water absorption and thickness swelling values in comparison to the panels with UF resin. However, mechanical properties of panels containing UF resin were generally higher; this was partially attributed to the higher resin content. It was concluded that panels with PF resin are recommended for applications where panels may be more exposed to water and vapor. In cases where the mechanical properties are of prime importance, panels with UF resin are more preferable. NC can be recommended in panels containing UF-resin to improve the properties, while it is not recommended in panels with PF-resin. Moreover, chicken feather can be included in MDF furnish to provide part of raw materials, though its addition can have diminishing effect on the properties to some extent., Ploče vlaknatice srednje gustoće (MDF) izrađene su uz dodatak dviju različitih smola, ureaformaldehidne (UF) i fenolformaldehidne (PF), i to u udjelu od 10 odnosno 8 %. Kako bi se pronašao novi izvor sirovine i pritom zadovoljile povećane potrebe industrije kompozitnih materijala, smjesi sirovine za izradu ploča vlaknatica dodano je 10 % pilećeg perja. Nadalje, dodana joj je i nanoglina da bi se istražilo moguće poboljšanje MDF ploča. Rezultati su pokazali da su ploče s PF smolom znatno slabije upijale vodu i da im je debljinsko bubrenje u odnosu prema pločama s UF smolom bilo manje. Međutim, mehanička svojstva ploča koje su sadržavale UF smolu u osnovi su bila bolja, što je djelomično povezano s većim udjelom smole. Zaključeno je da se ploče s PF smolom preporučuju za primjenu u uvjetima veće izloženosti vodi i pari. Kada su, pak, važnija mehanička svojstva ploča, pogodnije su one s UF smolom. Nanoglina se preporučuje za poboljšanje svojstava ploča koje sadržavaju UF smolu, a ne preporučuje se za ploče s PF smolom. Nadalje, pileće se perje može dodati sirovini za izradu MDF ploča iako ono može donekle pridonijeti pogoršanju svojstava ploče.

Nanocomposite polyHIPE foams with open-cellular morphology were obtained using nanoparticles ($γFe_2O_3/Fe_3O_4$), surfactant (Pluronic L121) or nanoparticle/surfactant stabilized dicyclopentadiene high internal phase emulsions (DCPD HIPEs). Upon curing, cavity sizes were found to vary drastically between 950 ± 360 µm down to 7 ±3 µm de- pending on the HIPE formulations. As-obtained nanocomposite polyHIPE foams were functionalized using elemental bromine in THF. Upon bromination the nanoparticles are moved from the cavities surfaces into the bulk phase of the polymer scaffold, which affects the inductive-heating capability of the magnetic nanocomposite foams decreasing it by the factor of 2. V tem strokovnem članku opisujem pripravo makroporoznih nanokompozitnih pen iz diciklopentadienskih HIP emulzij stabiliziranimi z $γFe_2O_3/Fe_3O_4$ nanodelci, t.i. Pickering emulzij in HIP emulzij stabiliziranimi s kombinacijo surfaktanta in nanodelcev. Tako pripravljene nanokompozitne pene smo primerjali s penami pripravljenimi iz HIP emulzij stabiliziranimi le s surfaktanti in ugotovili da se premer por spreminja in sicer od 7 ± 3 m do 950 ± 360 µm. V nadaljevanju smo nanokompozitne makroporzne pene funkcionalizirali z elementarnim bromom, ter raziskali vpliv bromiranja na samo lokacijo nanodelcev in sposobnost $γFe_2O_3/Fe_3O_4$ nanodelcev da ob prisotnosti zunanjega alternirajočega magnetnega polja proizvajajo toploto. V ta namen smo bromirano nanokompozitno peno izpostavili zunanjemu izmeničnemu magnetnem polju, ter ugotovili da se sposobnost segrevanje zmanjša za faktor 2.

Series of cross-linked polystyrene samples were prepared using an emulsion templating approach, where monomers were contained in the continuous phase of the emulsion, while the droplet aqueous phase induced primary pores, connected with a number of secondary pores. Emulsions with a high fraction of the droplet phase (HIPEs) were used and stabilised with a combination of a surfactant (sorbitan monooleate) and various types of particles (charcoal powder, copper powder and carbon nanopowder). The morphology of the resulting porous polymer depends on the type and amount of the particles added to the emulsion however, in all the cases open-cellular morphology was formed. The size of the primary pores (cavities) ranged from 5 µm to 25 µm, while the size of the secondary interconnecting pores was from 1 µm to 5 µm. The materials were investigated using scanning electron microscopy and nitrogen adsorption/desorption. Z uporabo emulzij z visokim deležem notranje faze smo pripravili serijo zamreženih polistirenskih vzorcev. Monomeri so bili vsebovani v kontinuirni fazi emulzije, kapljice notranje vodne faze pa so povzročile poroznost materiala z vrsto primarnih por, povezanih s povezovalnimi porami. Emulzije z visokim deležem notranje faze (HIPE) smo stabilizirali z uporabo surfaktanta v kombinaciji z različnimi delci (oglje v prahu, baker v prahu in ogljikov nanoprah). Na morfologijo pripravljenih odprtoporoznih materialov sta vplivala tako vrsta kot tudi količina dodanih delcev. Velikost primarnih por je bila v območju med 5 µm in 25 µm, medtem ko je bila velikost sekundarnih povezovalnih por v območju med 1 µm in 5 µm. Materiale smo karakterizirali z uporabo vrstičnega elektronskega mikroskopa in adsorpcijo/desorpcijo dušika.

The aim of this thesis was to prepare composite nanomaterials for targeted delivery of radionuclides used for cancer diagnosis and therapy. Hydroxyapatite and TiO2 nanoparticles were used as vehicles for targeted delivery because of their suitable properties such as biocompatibility and radiochemical stability. Nanocomposites were prepared by precipitating phosphonate ligands or polyethylene glycol with nanoparticles. The role of the phosphonates is binding of radionuclides and stabilisation of nanoparticles. Prepared nanocomposites were labelled with 99mTc, a gamma emmiter used in tumor imaging and 223Ra, an alpha emmiter used in targeted alpha therapy. Phosphonic acids ethylenediamine tetra(methylenephosphonic) acid, propylenediamine tetra(methylenephosphonic) acid and 1,2-cyclohexyldiamine tetra(methylenephosphonic) acid were purified by ion exchange chromatography and used for preparation of nanocomposites. Besides mentioned ligands, methylene diphosphonic acid, etidronic acid, zoledronic acid, pamidronic acid and polyethylene glycol were used for experiments. For labelling with 99mTc, the best yields were obtained for 99mTc-CDTMP-HAp (89%), and 99mTc-PDTMP-HAp (93%) stabilised before labelling and 99mTc-MDP-HAp (92%) and 99mTc-HEDP-HAp (89%) stabilised during their preparation. TiO2 nanocomposites all had yields >93%. Nanocomposites 223Ra-zoledronic acid-HAp stabilised after labelling showed the best yields (60%) for labelling with 223Ra. Cilj ovog rada bio je priprema kompozitnih nanomaterijala za ciljanu dostavu radionuklida koji se koriste u dijagnostici i terapiji raka. Nanočestice hidroksiapatita i TiO2 korištene su kao nosači za ciljanu dostavu zbog njihovih pogodnih svojstava, kao što su biokompatibilnost i radiokemijska stabilnost. Nanokompoziti su pripravljeni miješanjem fosfonatnih liganda ili polietilen glikola s nanočesticama. Uloga fosfonata je vezanje radionuklida i stabilizacija nanočestica. Pripremljeni nanokompoziti obilježeni su s 99mTc, radionuklidom koji emitira gama zračenje i koristi se u dijagnostici tumora te 223Ra, koji emitira alfa zračenje i koristi se u ciljanoj alfa terapiji. Fosfonske kiseline, etilendiamin tetra(metilenfosfonska) kiselina, propilendiamin tetra(metilenfosfonska) kiselina i 1,2-cikloheksildiamin tetra(metilenfosfonska) kiselina, pročišćene su ionsko izmjenjivačkom kromatografijom i korištene su za pripravu nanokompozita. Osim navedenih liganda, u eksperimentima su korištene i metilen difosfonska, etidronska, zoledronska i pamidronska kiselina te polietilen glikol. Za obilježavanje s 99mTc, najbolje iskorištenje dobiveno je za 99mTc-CDTMP-HAp (89%), i 99mTc-PDTMP-HAp (93%) stabilizirane prije označavanja i 99mTc-MDP-HAp (92%) i 99mTc-HEDP-HAp (89%) stabilizirane tijekom sinteze nanočestica. Svi nanokompoziti TiO2 imali su iskorištenje veće od 93%. Nanokompoziti 223Ra-zoledronska kiselina-HAp stabilizirani nakon obilježavanja pokazali najbolje iskorištenje (60%) za označavanje s 223Ra.

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.

Pētīti Ba ferrita-polikarbonāta nanokompozīti. Auto sadegšanas reakcijas metode izmantota, lai iegūtu Ba ferrita nanodaļiņas, kuri vidējais izmērs bija 40 nm.

Materials for practical smart sensor applications are attracting serious interest over last few years. The major problem of conventional rigid sensor materials are difficulty to integer them into soft flexible structures. Polyisoprene/nanostructured carbon composite appears as promising materials for such application. Previous research approved nanostructured carbon black filled composites as finger pressure sensitive piezoresistive materials [1]. The change of tunneling currents between carbon aggregates causes rapid change of composite electrical conductivity under applied external load. Thus current phenomena can only be achieved if high structure carbon blacks (DBP apsorption is 380ml/100g) are used as conductive filler. Single and multi wall carbon nanotubes (CNT) originate with variable length to width ratio and high electric conductivity in longitudinal direction of tube. The specific properties mentioned above should make it possible to obtain electric percolation in polymer-CNT composites at very low loads of filler. However our recent experience [2] shows quite high value of percolation threshold but still good sensing properties in the vicinity of percolation region, if the CNT has been dispersed by “roll in” method. In this work an attempt to reduce percolation threshold of polyisoprene/multiwall CNT composite by sonicated and stirred dispersion of CNT in chloroform solution is presented. The percolation threshold and the excellent piezoresistive behavior of polyisoprene/multiwall CNT composite have been determined as well.

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.

Poboljšanje adhezijskih svojstava na međupovršini u nanokompozitima, u odnosu na standardne mikrokompozite, posljedica je velike specifične površine nanopunila i uspostavljenih interakcija na nanorazini. U ovom radu dan je pregled rezultata istraživanja svojstava međupovršine i svojstava materijala u uvjetima promjene parametara adhezije kontroliranom predobradom površine punila. Predobrada nanopunila kalcijeva karbonata (CaCO3) silanom, stearinskom kiselinom, radijacijskim cijepljenjem poli(vinil-acetata) i/ili njihovom kombinacijom mijenja adhezijske parametre na međupovršini u istraživanim kompozitima i polimernim mješavinama na osnovi poliuretana (PUR) i poli(vinil-acetata) (PVAC). Energija površine komponenata u kompozitu i polimernoj mješavini mjerena je metodom kontaktnoga kuta. Morfologija je istražena primjenom optičke mikroskopije, a mehanizam popuštanja kompozita tehnikom pretra`ne elektronske mikroskopije (SEM). Mehanička svojstva kompozitnih sustava određena su rasteznim ispitivanjem, a toplinska svojstva metodom diferencijalne pretražne kalorimetrije (DSC). Strukturne promjene matrice pod utjecajem nanopunila analizirane su metodom raspršenja rendgenskih zraka pod malim kutom (SAXS). Rezultati poboljšanja mehaničkih svojstava polimernih sustava punjenih nanočesticama u vezi su s postignutom homogenom morfologijom i smještanjem nanopunila na međupovršini u uvjetima optimalne adhezije. Uvjeti optimalne adhezije u kojima je energija međupovršine minimalna i teži nuli, a postižu se kontroliranom predobradom površine punila, rezultiraju znatno boljim svojstvima u odnosu na sustave u kojima su uvjeti na međupovršini daleko od optimalnih., Improvements in adhesive properties at the interface in nanocomposites, with respect to the standard microcomposites, are a consequence of the great specific surface area of nanofillers and established interactions at nanolevel. An overview of investigations related to the interface and material properties in the conditions of the changed parameters of adhesion by the controlled pre-treatment of the filler surface is given in this paper. The pre-treatment of nanofiller calcium carbonate (CaCO3) by silane, stearic acid, irradiation grafting of poly(vinyl-acetate) and/or its combination changed the adhesion parameters at the interface in the investigated composites and polymer blends based on polyurethane (PUR) and poly(vinyl acetate) (PVAC). The surface energy of the components in the composite and polymer blends is measured by a contact angle technique. The morphology of composites is investigated by the optical polarization microscopy and the failure mechanism by the scanning electron microscopy (SEM). Mechanical properties of composites are determined by a tensile test and thermal properties by the differential scanning calorimetry (DSC) technique. Structural changes of the matrix under the influence of nanofillers are analyzed by the small angle X–ray scattering (SAXS) technique. Improved results in mechanical properties are related with the homogeneous morphology and the preferential location of nanofillers at the interface. Conditions of the optimal adhesion when the interfacial energy between nanofillers and a particular matrix is minimal and tends to zero can be achieved by a controlled filler surface pre-treatment. They result in significantly improved properties in comparison to the systems with the conditions at the interface that cannot match the optimal ones.

Razvoj polimernih nanokompozitov predstavlja pomemben inovacijski potencial pri načrtovanju polimernih materialov z izboljšanimi lastnostmi. Kljub izjemnim prednostim polipropilena (PP), predvsem izotaktičnega PP (iPP), je v razvoju novih polimernih materialov še vedno velika pozornost namenjena njegovim modifikacijam z različnimi polnili. V zadnejm obdobju so se raziskave iPP mikrokompozitov razširile še na študij iPP nanokompozitov, ki so odličen substitut za osnovne polimerne materiale in polimerne mikrokompozite. Preučevali smo binarne - iPP/silika in ternarne - iPP/silika/PP-g-MA nanokompozite. Vzorce smo pripravili v talini v Brabenderjevem sistemu in s stiskanjem v plošče na laboratorijski stiskalnici. V ta namen smo uporabili komercialno dosegljiva tipa nanosilike, ki se med seboj razlikujeta po površinski obdelavi in specifični površini. Vzorce smo karakterizirali s preučevanjem predelovalnih lastnosti s torzijsko reometrijo, preučevanjem mehanskih lastnosti z merjenjem nateznih lastnosti in zarezne udarne žilavosti ter trdote po Shoru D, morfologijo pa smo opredelili z vrstično elektronsko mikroskopijo. Rezultati raziskav so pokazali, da s površinsko obdelavo silike dosežemo večjo hidrofobnost površine polnila in s tem boljšo kompatibilnost z nepolarnim iPP. Z dodajanjem kompatibilizatorja PP-g-MA smo dosegli izboljšanje predelovalnih lastnosti. Nanodelci silike niso individualno dispergirani v polimerni matriki, temveč bolj ali manj kot aglomerati. Stopnja aglomeracije je odvisna od količine dodane nanosilike, kot tudi od njenega hidrofilnega ali hidrofobnega značaja. Najustreznejši profil mehanskih lastnosti binarnih iPP/silika nanokompozitov je bil ugotovljen pri uporabljenih 2 vol. % polnila. Pri ternarnih iPP/silika/PP-g-MA nanokompozitih smo ugotovili, da je za doseganje ustreznega profila mehanskih lastnosti potrebno v primeru dodatka hidrofilnega polnila uporabiti več PP-g-MA. Pri hkratnem dodajanju silike in kompatibilizatorja je glede togosti ugotovljen sinergijski učinek (večje vrednosti Youngovega modula kot pri ustreznih binarnih kompozitih), medtem ko se žilavost lažje uravnava in dosega višje vrednosti pri uporabi obdelanega polnila

Organsko-anorganski hibridni materijali nova su vrsta nanostrukturirani materijala koji ujedinjuju svojstva obiju faza od kojih se sastoje. Hibridni materijali s polimernom maticom mogu se nazvati i nanokompozitima kod kojih punilo nastaje unutar matice, što omogućuje mnogo bolji doticaj među fazama. U ovom radu dan je pregled hibridnih materijala na osnovi epoksidne smole, sa silicijoksidnim punilom nastalim in situ sol-gel postupkom. Morfologija anorganske faze ovisi o uvjetima hidrolize polaznih alkoksida i prisutnosti dobro umrežene polimerne faze, a većinom nastaje interpenetrirana mreža anorganske i polimerne faze. Neumrežena organska faza ne utječe na nastajanje anorganske faze sol-gel postupkom, a nehidrolizirani alkoksidi nemaju utjecaja na reakcije epoksidnih skupina. Svojstva hibrida poboljšavaju se stvaranjem kovalentnih veza među fazama, dok svi hibridi pokazuju povećanu toplinsku postojanost u usporedbi s nemodificiranom epoksidnom smolom. Porast udjela anorganske faze iznad optimalnog ne poboljšava, ili čak pogoršava mehanička svojstva hibridnih materijala., 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. This paper gives an overview of the hybrid materials based on epoxy resin with silica filler formed by in situ sol-gel process. The morphology of the inorganic phase depends on hydrolysis of alkoxides and the presence of crosslinked polymeric phase, and in most cases an interpenetrated organic-inorganic network is formed. Uncrosslinked organic phase does not influence sol-gel reaction of the inorganic phase, and unhydrolysed alkoxides do not influence the reactions of epoxy groups. The presence of covalent bonding between the phases improves the properties of hybrid materials, and all hybrids show improved thermal stability in comparison with unmodified resin. The increase of inorganic phase content above the optimal one does not improve, or even deteriorates the mechanical properties of the hybrids.