Ricinusovo ulje kao obnovljiva sirovina za dobijanje poliuretanskih materijala

Traditionally, polyurethanes (PU) are manufactured by reacting isocyanates with petroleum-based polyols (polyether or polyester). Because oil resources are diminishing and are becoming expensive to produce, engineers and scientist have discovered new technologies to fabricate plastics from renewable resources. The goal of this work was to determine mechanical properties of polyurethanes synthesized from castor oil and different isocyantes: isophorone diisocyanate IPDI, 1,6-diisocyanatohexane (HDI) and aliphatic polycyclotrimer (HDIt). The samples were prepared by a one-step reactive process with stoichiometric balance of reactive groups. The catalysed synthesis was performed at normal pressure. It was estimated that a mechanical properties of prepared samples were strongly influenced by the isocyanate type.Tradicionalno se poliuretani (PU) dobijaju reagovanjem izocijanata sa poliolima (polietarski i poliestarski) koji se uobičajeno dobijaju iz nafte. Pošto se ti resursi smanjuju i postaju sve skuplji inženjeri i naučnici su razvili nove tehnologije za proizvodnju plastike iz obnovljivih sirovina. Cilj ovog rada je bio da se odrede mehanička svojstva poluretanskih materijala dobijenih jednostepenim reaktivnim procesom od ricinusovog ulja i različitih izocijanata: izoforon diizocijanata (IPDI), 1,6-diisocianatoheksana (HDI) i alifatičnog poliizocijanata ciklotrimera (HDIt) sa stehiometrijskim balansom reaktivnih grupa. Katalitička sinteza se odvijala na normalnom pritisku. Ustanovljeno je da su mehanička svojstva dobijenih materijala bila uslovljena tipom izocijanata

Razvoj postupaka polimerizacije L-laktida

To determine the appropriate conditions for the polymerization of (Llactide), to obtain poly(L-lactide) a few different methods were applied: in closed vials under vacuum, in the reactor under high pressure, in the microwave reactor and in a reactor with solvent using the initiator. The molecular masses of prepared samples were determined using GPC method. It was assessed that by microwave synthesis method for the polymerization time less than 30 minutes the resulting polymer have the highest molecular mass, 178.000 g mol-1. It was estimated that the samples synthesized with trifluoromethanesulfonic acid as initiator have the best thermal stability.Za određivanje optimalnih uslova za polimerizacije (L- laktida), za dobijanje poli (L-laktida) (PLLA) primenjene su različite metode polimerizacije: u zatvorenim posudama pod vakumom, u reaktoru pod visokim pritiskom, mikrotalasnom polju i u rastvoru sa inicijatorom. Za određivanje molekulskih masa korišćena je GPC metoda. Ustanovljeno je da je mikrotalasna sinteza postupak sa najkraćim vremenom polimerizacije (manjim od 30 minuta) pri čemu je nastaje polimer koji ima najveću molarnu masu 178.000 g mol-1. Najbolju termičku stabilnost imao je uzorak PLLA sintetisan sa trifluorometansulfonskom kiselinom kao inicijatorom

Strukturiranje i primena materijala na osnovu biopolimera hitozana

Derived from chitin, chitosan is a unique biopolymer that exhibits, beside biocompatibility and biodegradability, outstanding adsorption properties. The layer-by-layer (LBL) deposition technique is based on the alternated adsorption of materials bearing complementary charged or functional groups, in aqueous medium. As a consequence of the polycationic nature of chitosan, chitosan-based films can be used as sensors, drug delivery systems and in tissue engineering. The goal of work was to obtain innovative nano-composites beads based on hitosan, alginate and iron-oxide prepared using LBL deposition method, as magnetic adsorbents used for the separation of dyes from solutions and suspensions.Hitozan je jedinstveni biopolimer koji, pored biokompatibilnosti i biodegradabilnosti, pokazuje i odlična adsorpciona svojstva. Sloj po sloj tehnika (layer-by-layer, (LBL)) se zasniva na naizmeničnoj adsorpciji materijala sa komplementarno naelektrisanim ili funkcionalnim grupama, u vodenoj sredini. Polikatjonska priroda hitozana omogućava njihovu primenu u LBL procesima, i zbog toga se filmovi na osnovu hitozana koriste kao senzori, nosači lekova i u inženjerstvu tkiva. Cilj rada je strukturiranje inovativnih nanokompozitnih granula na osnovu hitozana, alginata i Fe2O3 primenom LBL tehnike radi njihove primene kao magnetnih adsorbenata za uklanjanje boja iz rastvora i iz suspenzija

Dobijanje razgranatih kopoliestara od ricinusovog ulja kao inicijatora

Using renewable feedstocks, such as biomass, for the production of polymers can have both environmental and economic benefits. The goal of this project was to synthesize the renewable copolymers from monomer l-lactide and castor oil as an initiator. In sample formulation the mass ratio of the monomer to the initiator was in the range from 4,53 to 21,5. The ring-opening polymerization was carried in a microwave reactor using tin(II)2- ethylhexanoate as a catalyst. The molar masses of obtained star-shaped polymers were assessed using SEC method. The thermal properties of the branched polymer were evaluated using differential scanning calorimetry. The molecular mass of the branched polymer increased with increasing the feed ratio of lactide and castor oil.Korišćenje obnovljivih sirovina, kao što je biomasa, za proizvodnju polimera može da ima i ekološke i ekonomske prednosti. Cilj ovog rada je bila sinteza obnovljivih kopolimera na osnovu monomera L-laktida i ricinusovog ulja kao inicijatora. U sirovinskom sastavu uzoraka maseni odnos monomera L-laktida i inicijatora ricinusovog ulja bio je u opsegu od 4,53 do 21,5. Polimerizacija otvaranjem prstena je izvršena u mikrotalasnom reaktoru primenom kalaj(II)etilheksanoata kao katalizatora. Molske mase dobijenih zvezdastih polimera su određene pomoću SEC metode. Toplotna svojstva razgranatih polimera određena su metodom diferencijalne skenirajuće kalorimetrije. Molske mase razgranatog polimera rastu sa porastom masenog odnosa laktida i ricinusovog ulja

Metode uklanjanja fenola iz otpadne vode

Phenol is a major pollutant in the wastewater because of its presence in the effluent of major processing and refining plants. It has severe effect on human being, both short term and long term. Various methods are used for removal of the phenol from wastewater such as adsorption, photodecomposition, volatilization and other various biological and non-biological methods. In the present study attempt is done to present the survey of the research on the phenol removal by various methods. The methods such as polymerization, electrocoagulation, extraction, photodecomposition, advanced oxidation and ion exchange were used effectively by various investigators. These methods are reported to be efficient for the phenol removal. Suitable method for phenol removal can be selected based on availability of the material, extent of separation required and properties of phenolic effluent.Fenol je jedan od glavnih polutanata u otpadnoj industrijskoj vodi. Utiče na zdravlje ljidi i taj uticaj se ispoljava kako posle kraćeg tako i posle dužeg prisustva. Za uklanjanje fenola iz otpadne vode koriste se metode kao što su adsorpcija, fotorazgradnja, isparavanje (volatilizacija) kao i biološke i nebiološke metode. U ovom radu daje se prikaz istraživanja o uklanjanju fenola različitim metodama kao što su polimerizacija, elektrokoagulacija, fotorazgradnja, unapređena oksidacija i jonska izmena. Izbor metode za uklanjanje fenola može biti učinjen na osnovu raspoloživog materijala, zahtevanog intenziteta prečišćavanja i osobina fenolnog efluenta

Hitozan/bentonit granule za tretman otpadnih voda

Aim of this research was synthesis of chitosan/bentonite nanocomposite beads for colored wastewater treatment by adsorption. Influence of preparation procedure on the morphology, adsorption and thermal properties has been studied. It was proved that procedure method affects morphology, as well as enthalpy of absorbed water evaporation, which depends on the molarity of NaOH, and does not affect glass transition temperature. Chitosan adsorption capacity was improved by addition of modified bentonite, which is desirable in colored wastewater treatment.Cilj ovog istraživanja je bila sinteza hitozan/bentonit nanokompozitnih granula za prečišćavanje obojenih otpadnih voda metodom adsorpcije. Proučavan je uticaj postupka pripreme na morfologiju, kao i na adsorpciona i toplotna svojstva nanokompozitnih biopolimera. Dokazano je da način pripreme hibridnih granula utiče na morfologiju, kao i na entalpiju isparavanja adsorbovane vode čija vrednost zavisi od molarnosti NaOH, a ne utiče na temperaturu prelaska u staklasto stanje. Sposobnost adsorpcije hitozana je poboljšana dodavanjem modifikovanog bentonita, koji je poželjan u tretmanu obojenih otpadnih voda

Synthesis, characterization and kinetics of sustained pantoprazole release studies of interpenetrated poly(acrylic acid)-chitosan-bentonite hydrogels for drug delivery systems

Clays are widely used in controlled drug delivery systems due to their strong adsorption properties and natural origin. In this study, a drug carrier was prepared using chitosan, a natural polymer, mixed with bentonite clay. Then, poly(acrylic acid) was added to improve its swelling properties. Pantoprazole was chosen as the model drug. The swelling properties of the prepared samples were investigated at two different temperatures: 25 and 37 degrees C. The prepared samples were examined by Fourier-transform infrared spectroscopy and scanning electron microscopy. The controlled release of the pantoprazole from the drug carriers indicated that the release of the pantoprazole is temperature-sensitive. In order to study the effect of bentonite on the drug carrier system, drug release was also investigated in the samples without adding clay. It was observed that the drug release profiles of the prepared sample containing bentonite fitted better than the sample without clay. The release kinetics analysis showed that the first-order and the Korsmeyer-Peppas models fit the best, and that pantoprazole was transported via Fickian diffusion. The prepared samples showed the capability of pantoprazole loading and, thus, its possibility to be used in drug delivery systems