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Spherical TiO2 particles of different size were dispersed in alkyd resin based on soybean oil. Four samples of TiO2 particles were used, three commercial and one obtained by acid catalyzed hydrolysis of titanium tetraisopropoxide. The size of the synthesized nanoparticles was determined by transmission electron microscopy. Surface modification of TiO2 nanoparticles was performed with propyl gallate and lauryl gallate. The influence of the size of TiO2 nanoparticles, their concentration and type of the surface modification on the rheological properties of alkyd resin was investigated. The obtained results have shown that the viscosity of the prepared dispersions was higher than the viscosity of the pure resin, increases with decreasing particle diameter and decreases with frequency increase. Surface modified particles showed higher influence on the viscosity of alkyd resin than unmodified, because their hydrodynamic volume is higher due to the presence of the adsorbed gallates, leading to the increase of effective volume fraction of particles in dispersion. For the lowest TiO2 concentration, the viscosity was higher for the sample modified with lauryl gallate, due to the higher thickness of the adsorbed layer. The increase of concentration, because of less dispersion stability of the particles modified with propyl gallate, leads to particle agglomeration. The presence of agglomerates, which was confirmed by a change in the slope of the functional dependence of storage modulus on loss modulus, leads to a rapid increase in viscosity. Sferne čestice TiO2 različitih veličina dispergovane su u alkidnoj smoli. Površinska modifikacija nanočestica TiO2 izvedena je propil galatom i lauril galatom. Ispitivan je uticaj veličine nanočestica TiO2, koncentracije, kao i vrste površinske modifikacije na reološka svojstva alkidne smole. Dobijeno je da je viskoznost pripremljenih disperzija veća od viskoznosti čiste smole, da raste sa smanjenjem prečnika čestica i opada sa povećanjem frekvencije. Površinski modifikovane čestice imaju veći uticaj na viskoznost alkidne smole nego nemodifikovane zbog povećanja efektivnog zapreminskog udela čestica u disperziji. Za najmanju koncentraciju TiO2 viskoznost je veća kada je modifikacija izvršena lauril galatom, dok sa povećanjem koncentracije, zbog manje disperzione stabilnosti čestica modifikovanih propil galatom, dolazi do njihove aglomerizacije i naglog povećanja viskoznosti.

Two series of crosslinked poly(urethane-ester-siloxane)s were synthesized from α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS- -EO), 4,4'-methylenediphenyl diisocyanate and Boltorn® hyperbranched polyesters of the second and third pseudo generation, by two-step polymerization in solution. The effect of the EO-PDMS-EO content and functionality of the applied crosslinking agent on the morphology and surface properties of the prepared poly(urethane-ester-siloxane)s was investigated by FTIR spectroscopy, small-angle X-ray scattering (SAXS), atomic force microscopy (AFM), scanning electron microscopy (SEM) and water absorption measurement. Different techniques (FTIR peak deconvolution, SAXS and AFM) revealed that decrease of the crosslinking agent functionality and EO-PDMS-EO content promotes microphase separation in the synthesized poly(urethane-ester-siloxane)s. SEM analysis and water absorption experiments showed that, due to the hydrophobic character of EO-PDMS-EO and its ability to migrate to the surface of poly(urethane-ester-siloxane)s, samples synthesized with higher EO-PDMS-EO content and crosslinking agents of lower functionality had more hydrophobic surfaces and better waterproof performances. The obtained results indicate that the synthesis of poly(urethane-ester-siloxane)s based on EO-PDMS-EO and Boltorn® hyperbranched polyesters leads to the creation of networks with interesting morphological and surface properties, which can be easily tailored by changing the content of EO-PDMS-EO segment or functionality of hyperbranched polyester. U ovom radu sintetisane su dve serije umreženih poli(uretan-estar-siloksana) (PUS) korišćenjem α,ω-dihidroksi-(etilenoksid-poli(dimetilsiloksan)-etilenoksida) (EO-PDMS-EO), 4,4'-diizocijanatodifenilmetana i dva Boltorn® hiperrazgranata poliestra (HRP) druge i treće pseudo generacije kao umreživača. Svaka serija se sastoji od uzoraka koji imaju različiti udeo mekog segmenta (EO-PDMS-EO). Uticaj funkcionalnosti korišćenog HRP i udela mekog segmenta na morfologiju i površinska svojstva PUS ispitan je primenom FTIR spektroskopije, SAXS, AFM i SEM analize i merenjem količine apsorbovane vode. Pokazano je da sa smanjenjem funkcionalnosti umreživača i udela EO-PDMS-EO dolazi do povećanja stepena mikrofaznog razdvajanja kod sintetisanih PUS. Pored toga, uzorci PUS sa većim udelom mekog segmenta i sintetisani primenom HRP niže funkcionalnosti pokazuju bolju otpornost na vodu.

A series of novel polyurethane crosslinked structures (PUs) was prepared from α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS-EO), 4,4'-methylenediphenyl diisocyanate and Boltorn ® hyperbranched polyester of the third pseudo generation. The hydroxyfunctional hyperbranched aliphatic polyester with 26 end groups was used as a crosslinking agent. In order to improve the compatibility of all the reactants during the synthesis, the PU samples were prepared by two-stage, step-growth polymerization in solution. The content of the soft EO-PDMS-EO segments was varied in the range from 15 to 40 wt. %. The influence of the EO-PDMS-EO content on the swelling behavior, crosslink density, hardness, and the thermal and surface properties of the synthesized PUs was investigated. The structure of the synthesized polyurethanes was confirmed by the presence of specific bands in the Fourier transform infrared spectra. Swelling studies were performed to determine the crosslink density and polyurethane networks with lower EO-PDMS-EO contents had higher crosslink densities. The glass transition temperature of the synthesized PUs, determined by differential scanning calorimetry, slightly increased from 50 to 58°C on decreasing the EO-PDMS-EO content because of the higher crosslink density of the samples. Increasing the EO-PDMS-EO content led to better thermal stability, as was evidenced by the onset temperature of weight loss. The surface of the polyurethane networks became more hydrophobic with increasing EO-PDMS-EO content. The surface morphology of synthesized polyurethanes was analyzed by scanning electron microscopy. U ovom radu prikazana je sinteza, struktura i neka svojstva novih umreženih poliuretana pripremljenih polazeći od α,ω-dihidroksi-(etilenoksid-poli(dimetilsiloksan)-etilenoksid) pretpolimera (EO-PDMS-EO), 4,4'-metilendifenildiizocijanata i Boltorn® hiperrazgranatog poliestra treće pseudo-generacije. Hiperrazgranati hidroksi funkcionalni alifatski poliestar sa 26 krajnjih grupa služio je kao umrežavajući agens pri sintezi poliuretana. U cilju poboljšanja kompatibilnosti reaktanata tokom sinteze, poliuretani su sintetisani dvostepenom polimerizacijom u rastvoru. Sadržaj mekog EO-PDMS-EO segmenta variran je u opsegu od 15 do 40 mas. %. Ispitan je uticaj EO-PDMS-EO sadržaja na ponašanje pri bubrenju, gustinu umrežavanja, tvrdoću, termička i površinska svojstva sintetisanih poliuretana. Struktura sintetisanih poliuretana potvrđena je FTIR spektroskopijom. Ponašanje pri bubrenju je ispitivano kako bi se odredila gustina umrežavanja i pokazano je da poliuretanske mreže sa nižim EO-PDMS-EO sadržajem imaju veću gustinu umrežavanja. Rezultati diferencijalne skenirajuće kalorimetrije pokazali su povećanje temperature ostakljivanja poliuretana od 50 do 58°C sa smanjenjem EO-PDMS-EO sadržaja kao posledicu veće gustine umreženosti uzoraka. Sintetisani poliuretani sa većim sadržajem EO-PDMS-EO segmenata pokazuju bolju termičku stabilnost, što je potvrđeno porastom početne temperature degradacije, određene TG analizom. Hidrofobnost površine poliuretana je rasla sa povećanjem sadržaja EO-PDMS-EO u odgovarajućem uzorku. Površinska morfologija sintetisanih poliuretana je analizirana skenirajućom elektronskom mikroskopijom.

Two series of polyurethane films based on hyperbranched polyester of the second pseudogeneration (Boltorn?), 4,4'-methylenediphenyl diisocyanate and two different siloxane prepolymers, ?,?-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS-EO) and ?,?-dihydroxypropyl-poly(dimethylsiloxane) (HP-PDMS), were prepared by two-step polymerization in solution. The influence of the type and content of soft segment on the morphology, thermomechanical and surface properties of the synthesized polyurethanes was studied by atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), dynamic mechanical thermal analysis (DMTA) and water absorption measurements. It was found that these techniques confirmed existence of microphase separated morphology. Synthesized polyurethanes exhibited two glass transition temperatures and one second relaxation process. The results showed that polyurethanes based on HP-PDMS had higher surface roughness, better microphase separation and waterproof performances. Samples synthesized with lower PDMS content had less hydrophobic surface, but higher crosslinking density and better thermomechanical properties. (Projekat Ministarstva nauke Republike Srbije, br. 172062]

World packaging market achieves turnover of about $620 billion per year with one third of this amount being associated with packaging made from polymer materials. It is expected that this kind of packaging consumption will hold at least 3% of the world packaging market share in the next five years and that it will surpass the consumption of all other materials used in the packaging production. This can be contributed to product quality, low production costs as well as significant investments made in the development of polymer materials, packaging technology and packaging. This paper presents some development directions for packaging made from polymer materials, such as: packaging in protective atmosphere, the use of active and intelligent packaging, and the use of biopolymers and recycled polymers for packaging production that come into direct contact with the packed product. Na svetskom tržištu ambalaže godišnje se ostvari promet od oko 620 milijardi US dolara. Jedna trećina ove sume otpada na ambalažu od polimernih materijala. Očekuje se da će porast potrošnje ambalaže od polimernih materijala biti najmanje 3% u sledećih pet godina i da će biti veći od porasta potrošnje svih drugih materijala, koji se koriste za izradu ambalaže. Zbog kvaliteta i cene polimerni materijali polako istiskuju druge materijale i u ovoj oblasti primene. Veliki doprinos tome daju proizvođači polimernih materijala i ambalaže od polimernih materijala, kao i svi oni koji koriste ovu ambalažu za pakovanje svojih proizvoda, značajnim ulaganjem u razvoj polimernih materijala, tehnologiju izrade ambalaže i pakovanja. U okviru ovoga rada prikazani su neki od pravaca razvoja ambalaže od polimernih materijala, kao na primer: pakovanje u zaštitnoj atmosferi, primena aktivne i inteligentne ambalaže, sve veća primena biopolimera i reciklata polimera za izradu ambalaže koja dolazi u direktan kontakt sa pakovanim proizvodom.

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.