Search

Za djelatnu tvar koja se koristi u liječenju shizofrenije, olanzapin, bilo je potrebno pronaći otapalo koje je najpogodnije u vidu morfologije dobivenih kristala. Provedena je kristalizacija s izobutil acetatom, metl izobutil ketonom, etil acetatom i toluenom kao otapalom. Istraživanje je provedeno u šaržnom kristalizatoru. Zbog bolje morfologije kristala i krivulje topljivosti odabran je toluen kao najpogodnije otapalo te se daljnje istraživanje kristalizacije odvija u toluenu. U okviru ovog rada, istražen je utjecaj vrste miješala na morfologiju i granulometrijska svojstva kristala. Korištena su četiri različita miješala, od kojih se s dva miješala postiže aksijalni tok, a s dva radijalni tok. Također, istražen je utjecaj broja okretaja miješala na svojstva dobivenih kristala. Istraživanje je provedeno pri 150, 250 i 350 okretaja u minuti. U svrhu karakterizacije dobivenih kristala olanzapina u različitim uvjetima provedbe procesa, provedena je analiza kemijskog sastava metodom difrakcije rendgenskih zraka, analiza granulometrijskih svojstava gdje je raspodjela veličina čestica određena metodom laserske difrakcije te pomoću FBRM sonde, a morfologija kristala je analizirana optičkim i pretražnim elektronskim mikroskopom pod različitim uvećanjima. Toplinska svojstva kristala olanzapina istražena su diferencijalnim pretražnim kalorimetrom i termogravimetrijskom analizom. For the active pharmaceutical ingredient used in the treatment of schizophrenia, olanzapine, it was necessary to find the solvent which is most suitable in the form of the morphology of the crystals obtained. Crystallization was performed with isobutyl acetate, methyl isobutyl ketone, ethyl acetate and toluene as solvent. The research was conducted in a batch crystallizer. Due to the better crystal morphology and solubility curve, toluene was chosen as the most suitable solvent, and further crystallization research was carried out in toluene. In this work, the effect of the type of mixer on the morphology and granulometric properties of crystals was investigated. Four different mixers were used, of which two mixers achieve axial flow and two radial flow. Also, the effect of the stirrer speed on the properties of the obtained crystals was investigated. The study was conducted at 150, 250, and 350 rotations per minute. In order to characterize the obtained olanzapine crystals under different process conditions, the chemical composition was analyzed by X-ray diffraction, granulometric properties were also analyzed by measuring particle size distribution using laser diffraction method and FBRM probe, and crystal morphology was analyzed by optical and scanning electron microscope with different magnifications. The thermal properties of olanzapine crystals were investigated by differential scanning calorimeter and with thermogravimetric analysis.

Polimerni nanokompoziti su kompoziti kod kojih se barem jedna faza nalazi u nanodimenzijama. Različiti polimeri kao što su termoplasti i elastomeri mogu se koristiti za proizvodnju polimernih nanokompozita. Nanopunila mogu poboljšati mehanička svojstva samih polimernih materijala ako su manjih dimenzija od 100 nm. Tema istraživanja ovog rada je utjecaj višestjenih ugljikovih nanocjevčica (multiwalled carbon nanotubes - MWCNT) na toplinska svojstva, proces kristalizacije, mehanička svojstva te na morfologiju čistog polikaprolaktona (PCL) i nanokompozita (PCL/CNT) s različitim udjelom nanocjevčica. Nanokompoziti PCL/CNT dobiveni su na dva načina, umješavanjem MWCNT u taljevinu PCL-a u Brabender gnjetilici i dodavanjem MWCNT u otopinu PCL-a i tetrahidrofurana (THF). Toplinska karakterizacija materijala provedena je tehnikama toplinske analize: diferencijalnom pretražnom kalorimetrijom (DSC); dinamičko mehaničkom analizom (DMA). Mehanička svojstva ispitana su na mehaničkoj kidalici, a morfologija PCL i PCL/CNT nanokompozita snimljena je pretražnim elektronskim mikroskopom (SEM). Dobiveni rezultati pokazali su da je bolji način pripreme nanokompozita PCL/CNT u Brabender gnjetilici u odnosu na otopinu PCL/THF. Polymer nanocomposites are composites in which at least one phase is expressed in nanometers. Different polymers such as thermoplastic and elastomers can be used for polymer nanocomposites preparation. Nanofillers can improve mehanical properties of polymer materials if they are smaller than 100nm. The aim of this study is the influence of multiwalled carbon nanotubes (MWCNT) on thermal properties, crystallization process, mehanical properties and morphology of polycaprolactone (PCL) and nanocomposites (PCL/CNT) with different weight ratios of MWCNT. PCL/CNT nano-composites were obtained in two ways, first one was by mixing MWCNT in PCL melt in Brabender mixer and the second one was dissolving PCL in tetrahydrofuran (THF) and than adding MWCNT to solution. Thermal characterization was obtained by thermal analysis: differential scanning calorimetry (DSC); dynamic mechanical analysis (DMA). Mehanical properties were determined with universal testing machine. The morphology of PCL and PCL/CNT nanocomposites was recorded by scanning electron microscopy (SEM). The obtained results were compared and showed that a better way of preparing PCL/CNT nanocomposites is in Brabender mixer than dissolving PCL in THF.

Cilj ovoga rada bio je ispitati svojstva čistih komponenata polilaktida (PLA-S, PLA-N), polietilena visoke gustoće (PE-HD) i polietilena niske gustoće (PE-LD). Također, su ispitana svojstva pripremljenih polimernih mješavina PLA-S/PE-HD, PLA-S/PE-LD, PLA-N/PE-HD i PLA-N/PE-LD 95/5 i 90/10 bez i uz dodatak punila (TiO2, silika). Uzorci su umješavani u Brabender gnjetilici. Određena su mehanička i toplinska svojstva čistih komponenata i pripremljenih polimernih mješavina. Također, je ispitana morfologija na temelju mehaničkih svojstava odabranih uzoraka. Snimljeni su FTIR spektri čistih komponenata. Na temelju dobivenih rezultata zaključeno je da polimerne mješavine bez dodatka punila imaju manju prekidnu čvrstoću i rad loma u odnosu na čiste komponente. U mješavinama PLA-N kao bolje punilo se pokazao TiO2, dok je u mješavinama s PLA-S kao bolje punilo odabrana silika. Proučavanjem morfologija mješavina, zaključeno je da najveći utjecaj na mehanička svojstva ima raspodjela veličina čestica i dispergiranost faza. The aim of this study was to determine the properties of 95/5 and 90/10 PLA-S/PE-HD, PLA-S/PE-LD, PLA-N/PE-HD and PLA-N/PE-LD polymer mixtures prepared without and with filler addition (TiO2, silica). Also, properties of pure polylactide (PLA-S, PLA-N), high density polyethylene (PE-HD) and low-density polyethylene (PE-LD) have been tested. Samples were blended in the Brabender mixer. Mechanical and thermal properties of pure components and prepared polymer blends were obtained. The morphology of selected samples was tested. FTIR spectra of pure components were recorded. Based on the obtained results, it was concluded that the polymer blends without the addition of filler have lower strength at break than the pure component. In PLA-N blends, TiO2 has been shown, as a better filler, while in PLA-S blends silica was a better choice. Morphology studies showed that particle size distribution and phase dispersion have the greatest influence on the mechanical properties of the blends.

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). Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna., In this work, the influence of multiwalled carbon nanotubes (MWCNT) and carbon nanotubes modified with COOH groups (MWCNT-COOH) on the structure and properties of thermoplastic polyurethane (PU) were investigated. The samples of nanocomposite were prepared from a mixture of polyurethane and MWCNT in acetone by slow drying at room temperature. The effect of the addition of nanofillers on the spherulite structure of polyurethane and the distribution of the nanofillers in the PU matrix were analysed with optical polarization microscopy. Thermal properties in non-isothermal and isothermal conditions were investigated by differential scanning calorimetry (DSC). The results of contact angle measurement imply that modification of MWCNT surface with COOH groups changes its surface from hydrophobic to hydrophilic (Fig. 2 and Table 1). Optical polarization microscopy showed that the addition of both nanofillers disrupts the coarse spherulite morphology of the polyurethane matrix (Fig. 4 and Fig. 5). It was observed that, at the macro level, the modified MWCNT-COOH filler is better distributed in the PU matrix than is the MWCNT filler (Fig. 5). The DSC results showed that, in non-isothermal conditions, up to a certain amount, both nanofillers accelerate the crystallization of the soft segments of polyurethane. This effect is more pronounced in systems with MWCNT filler (Fig. 9). The results of the crystallization enthalpy during cooling showed that MWCNT filler, despite its worse distribution in the PU matrix, more significantly enhances crystallization of PU’s soft segment than does the MWCNT-COOH filler (Fig. 10). This conclusion can be ascribed to better compatibility between the nonpolar MWCNT filler and the nonpolar soft phase of the PU matrix, as well as to the previous scientific finding that functional groups at MWCNT surface decrease the nucleation effect of MWCNT. By analysing the melting peaks, it can be concluded that the PU systems with MWCNT compared to systems with MWCNT-COOH contain a higher proportion of less ordered crystalline soft phase (Fig. 11). In isothermal conditions, the MWCNT filler accelerates crystallization more significantly than does the MWCNT-COOH filler (Fig. 16). This work is licensed under a Creative Commons Attribution 4.0 International License.

Cilj ovog istraživanja bio je ispitati svojstva polimernih mješavina akrilonitril-butadien-stirena i polietilena niske gustoće (ABS/PE-LD) i akrilonitril-butadien-stirena i polietilena visoke gustoće (ABS/PE-HD) kao i svojstva čistih komponenata, tj. čistog akrilonitril-butadien-stirena (ABS), polietilena niske gustoće (PE-LD) i polietilena visoke gustoće (PE-HD). Uzorci su pripremljeni ekstruzijom. Ispitana su njihova mehanička i toplinska svojstva, te morfologija uzoraka. Na temelju dobivenih rezultata zaključeno je da je smjesa ABS/PE-LD 95/5 najbolja od ispitivanih po pitanju mehaničkih svojstava. The aim of this study was to examine the properties of polymeric mixtures of acrylonitrile-butadiene-styrene and low density polyethylene (ABS / PE-LD) and acrylonitrile-butadiene-styrene and high density polyethylene (ABS / PE-HD) as well as the properties of pure components, i.e. pure acrylonitrile-butadiene-styrene (ABS), low density polyethylene (PE-LD) and high density polyethylene (HDPE). Samples were prepared by extrusion. Their mechanical and thermal properties, as well as the morphology of the samples were examined. Based on the obtained results, it was concluded that the ABS / PE-LD 95/5 mixture was the best in terms of it's mechanical properties.

Cilj ovog istraživanja bio je ispitati utjecaj titanijevog dioksida kao nanopunila na svojstva polimernih mješavina PLA/PE-LD 90/10 i PLA/PE-HD 90/10, kao i na svojstva čistih komponenata, tj. čistog polilaktida (PLA), polietilena niske gustoće (PE-LD) i polietilena visoke gustoće (PE-HD). Korištena su tri nanopunila komercijalnih naziva P25 (praškasti TiO2), P25/20 (granulirani TiO2) i PC500 (praškasti TiO2). Uzorci su pripremljeni ekstruzijom te su određena njihova mehanička i toplinska svojstva, ispitana je morfologija uzoraka te su snimljeni FTIR spektri čistih komponenata. Na temelju dobivenih rezultata zaključeno je da punila povoljno utječu na sva mehanička svojstva jedino u slučaju polimerne mješavine PLA/PE-LD 90/10. Punila su poboljšala neka mehanička svojstva čiste komponente PE-LD, dok kod ostalih sustava dodatak nanopunila uzrokuje lošije mehaničko ponašanje u odnosu na nepunjene sustave. Od pripremljenih nanokompozita, najbolja svojstva je u većini slučajeva pokazao onaj koji je pripremljen dodatkom nanopunila P25. The aim of this study was to investigate the influence of titanium dioxide as a nanofiller on the properties of PLA/PE-LD 90/10 and PLA/PE-HD 90/10 polymer blends, as well as on the properties of pure polylactide (PLA), polyethylene low density (PE-LD) and polyethylene high density (PE-HD) components. Three different nanofillers were used – P25 (TiO2 powder), P25/20 (granulated TiO2) and PC500 (TiO2 powder). Samples were prepared by extrusion and their mechanical and thermal properties were investigated, as well as the morphology of the samples. Also, FTIR spectrum of PLA, PE-LD and PE-HD was recorded. Based on the results, it was concluded that fillers can improve mechanical properties of the PLA/PE-LD 90/10 blend. Fillers can also have beneficial effect on some mechanical properties of the pure PE-LD component. As for the rest of the composites, it was observed that the addition of nanofillers causes poorer mechanical behavior compared to unfilled blends and pure components. In most cases, the best properties showed nanocomposites prepared by addition of the P25 filler.

Cilj ovog rada bio je istražiti utjecaj različitih udjela polietilena (PE) na toplinska i mehanička svojstva, te morfologiju polimernih mješavina na osnovi polilaktida (PLA). Svrha miješanja PE s PLA bila je dobivanje biorazgradive polimerne mješavine sa što manjim udjelom petrokemijske sintetske komponente te sniženje cijene krajnjeg polimernog proizvoda. Kao druga komponenta u mješavinama na osnovi PLA korišteni su polietileni različitih gustoća, polietilen niske gustoće i visoke gustoće. Nadalje, s aspekta primjene polimernog proizvoda cilj je bio prevladati nedostatke PLA, kao što su visoki modul i krutost, uz zadržavanje dobrih svojstava izvorno visoke čvrstoće PLA, kako bi dobili čvrst, ali i elastičan te fleksibilan materijal. Zbog nemješljivosti komponenata nužno je dodavanje punila čija je svrha modifikacija međupovršine što omogućuje bolje povezivanje polimera i bolja mehanička svojstva. Kako bismo proučili djelovanje punila na sustav PLA/PE-LD i PLA/PE-HD, odabranim mješavinama dodano je nanopunilo CaCO3 (5 masenih %) te su ispitana svojstva pripremljenih nanokompozita. Karakterizacija čistih komponenata, mješavina i kompozita provedena je rasteznim ispitivanjem, ispitivanjem udarne žilavosti, razlikovnom pretražnom kalorimetrijom (DSC) i pretražnom elektronskom mikroskopijom (SEM). Dodatkom druge komponente, PE, dolazi do očekivanog smanjenja inicijalno visoke prekidne čvrstoće čistog PLA i do smanjenja modula i krutosti, dok se istezljivost povećava tek kod većih udjela PE u mješavinama. Najlošija svojstva kod oba sustava, s PE-LD i PE-HD, primjećuju se kod mješavina s istim udjelima oba polimera, PLA i PE. Nanopunilo je dodano mješavinama s malim udjelom polietilenske komponente. Nanopunilo se ne smješta na međupovršinu između nemješljivih polimera, ali utječe na poboljšanje svojstava sustava PLA/PE-LD. Utječe na poboljšanje čvrstoće i žilavosti, a povećava i kristalnost sustava PLA/PE-LD kojem se dodaje, dok na sustav PLA/PE-HD ne utječe značajnije. The aim of this study was to research the influence of polyethylene (PE), which is added in various amounts, on the thermal and mechanical properties, also, morphology of polymer blends based on polylactide (PLA). The purpose of blending PE with PLA was to produce a biodegradable polymer blends with a small amount of petroleum – based synthetic component and to reduce the price of final polymer product. As the second component in the PLA – based blends, polyethylenes of various densities were used, such as low density and high density polyethylene. Furthermore, from the point of application of the final polymeric product, the aim was to overcome the disadvantages of PLA, such as high modulus and stiffness, while maintaining good properties of PLA, such as high strength, to obtain firm, but elastic and flexible material. Due to the immiscibility of the components, it is necessary to add filler with the purpose to modify the interface between polymers which would provide better adhesion and mechanical properties of the material. In order to study the effect of filler on the PLA/LDPE and PLA/HDPE systems CaCO3 nanofiller (5wt. %) was added to the selected blends, and the properties of nanocomposites were tested. Pure components, blends and composites were characterized by tensile test and impact resistance examination, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). When the second component is added, it reduces the initial high strength at break of pure PLA and, also, module and stiffness, while the elasticity increases only with larger amounts of PE in blends. The worst properties for both systems, with LDPE and HDPE, are noticed for the mixtures with the same amounts of both polymers. Nanofiller was added to the mixtures with small amount of PE component. Nanofiller is not situated at the interface, but it still affects the properties of PLA/LDPE blends. Nanofiller improves strength and toughness; also it increases crystallinity of PLA/LDPE systems, but has no effect on mechanical properties of PLA/HDPE blends.

U ovom radu prvo su karakterizirane višestijene ugljikove nanocjevčice (MWCNT) te MWCNT modificiranih –COOH skupinama. Karakterizacija MWCNT, MWCNT-COOH provedena je Ramanovom spektroskopijom, termogravimetrijskom analizom, zatim pomoću pretražne elektronske mikroskopije, mjerenjem kontaktnog kuta, te određivanjem disperzivnosti u različitim otapalima. Zatim je istraživan učinak dodatka MWCNT te MWCNT–COOH u rasponu udjela od 0-4% mas. na svojstva poliuretana. Uzorci nanokompozita pripravljani su postupkom iz otopine poliuretana u acetonu te polaganim sušenjem otopina na sobnoj temperaturi. Učinak dodatka nanopunila na sferolitnu strukturu poliuretana te raspodjeljenost nanopunila u PU matrici anlizirana je optičkom polarizacijskom mikroskopijom. Toplinska svojstva u neizotermnim i izotermnim uvjetima istraživana su diferencijalnom pretražnom kalorimetrijom (DSC), a toplinska stabilnost termogravimetrijskom analizom (TGA). Električna provodnost uzoraka određivana je metodom četiri kontakta. Utjecaj dodatka punila na mehanička svojstva PU kompozita ispitana je testom jednoosnog istezanja. Ramanova spektroskopija pokazala je da MWCNT imaju veći udio nečistoća nego MWCNT-COOH. TGA analiza pokazala je da su MWCNT-COOH toplinski stabilnije od MWCNT. Rezultati SEM analize pokazali su da funkcionalizacija ne utječe na stupanj agregacije. Rezultati kontaktni kuteva ukazuju da se funkcionalizacijom s -COOH skupinom uvelike mijenja polarnost nanocijevčica. Rezultati određivanja disperzivnosti pokazali su da su obe vrste nanocjevčica jako dobro dispergirane u acetonu. Optička polarizacijska mikroskopija pokazala je da dodatak oba punila razrušava krupnu sferolitnu morfologiju poliuretana. Uočeno je da su na makrorazini modificirane MWCNT-COOH bolje dispergirane u masi uzorka nego čiste MWCNT. DSC rezultati pokazali su da u neizotermnim uvjetima do određenog udjela dodatak obje vrste MWCNT ubrzavaju kristalizaciju mekog segmenta poliuretana. U uvjetima izotermne kristalizacije MWCNT također znatnije ubrzavaju kristalizaciju nego MWCNT-COOH. Rezultati termogravimetrijske analize upućuju da se dodatkom obje vrste MWCNT znatno poboljšava toplinska stabilnost u čitavom rasponu udjela nanopunila. Rezultati vodljivosti pokazali su da se i dodatakom malih udjela MWCNT vodljivost znatno povećava. Rezultati ispitivanja mehanički svojstava nanokompozita ukazuju da dodatak obje vrste MWCNT punila snižava prekidnu čvrstoću i prekidno istezanje kompozita. In this study carbon nanotubes (MWCNTs) and MWCNTs modified with COOH groups were characterized. Characterization of MWCNTs, MWCNTs-COOH was performed by Raman spectroscopy, thermal analysis, then using scanning electron microscopy, by measuring the contact angle, and determining dispersibility in various solvents. After that the effect of the addition of MWCNTs and MWCNTs-COOH in range of 0-4% wt. on the properties of polyurethane were investigated. Samples of nanocomposite were prepared from solution of polyurethane in acetone and slowly drying the solution at room temperature. The effect of the addition of nanofiller on spherulite structure of polyurethane and distribution nanofiller in PU matrix were analyzed by optical polarization microscopy. Thermal properties in the non-isothermal and isothermal conditions were investigated by differential scanning calorimetry (DSC) and thermal stability by thermogravimetric analysis (TGA). The electrical conductivity of the samples was determined using four probe method. Effect of the addition of fillers on the mechanical properties of PU nanocomposites was examined by uniaxial deformation test. Raman spectroscopy showed that MWCNTs have a higher proportion of impurities than MWCNTs-COOH. TGA analysis showed that MWCNTs-COOH are more thermally stable than MWCNTs. The results of SEM analysis showed that the functionalization does not affect the degree of aggregation. The results of the contact angles indicate that the functionalization by COOH groups significantly changes the polarity of the nanotubes. The results of determining dispersibility showed that both types of nanotubes are very well dispersed in the acetone. Optical polarization microscopy showed that the addition of both nanofillers disrupts the spherulite morphology of polyurethane. It was noted that at the macro level modified MWCNTs-COOH are better distributed in the the sample than pure MWCNTs. DSC results showed that in the non-isothermal conditions up to the addition of a certain amount of both types of MWCNTs accelerate the crystallization of the soft segments of polyurethane. In terms of isothermal crystallization MWCNTs also significantly accelerate crystallization than MWCNTs-COOH. The results of thermogravimetric analysis indicate that the addition of both types of MWCNTs significantly improves the thermal stability. Conductivity results showed that the the addition of small amount of MWCNTs significantly increases the conductivity. The results of the mechanical properties of the nanocomposite show that addition of both types of fillers MWCNTs reduced tensile strength and elongation of the composite.

Novi trendovi u istraživanjima su pronalazak materijala koji bi konkurirali na tržištu svojim dobrim svojstvima, biodegradabilnosti i proizvodnji iz obnovljivih izvora energije. Polilaktid je jedan od takvih materijala, koji s dodatkom ugljikovih nanocjevčica može konkurirati na tržištu. U ovom radu provedena su istraživanja utjecaja dodatka različitih masenih udjela funkcionaliziranih ugljikovih nanocjevčica (MWCNT-COOH; MWCNT-COOC12H25) u polilaktid. Uzorci su zamiješani na Brabender gnjetilici postupkom u talini. Potom je ispitivana morfologija, mehanička svojstva i mehanizam loma pomoću mehaničke kidalice i pretražnog elektronskog mikroskopa. Toplinska svojstva ispitivana su metodom diferencijalne pretražne kalorimetrije, te toplinska stabilnost termogravimetrijskom analizom. Električna svojstva određivana su mjerenjem otpora metodom četiri probe. Rezultati su pokazali da se mehanička svojstva PLA sustava s MWCNT-COOH i MWCNT-COOC12H25 nanopunilima poboljšavaju najznačajnije do 2 % mas. PLA nanokompoziti (do 2 % mas.) s ugljikovim nanocjevčicama funkcionaliziranim dugim alkilnim lancima (MWCNT-COOC12H25) imaju nešto bolja svojstva od sustava s MWCNT-COOH zbog bolje raspodijeljenosti MWCNT-COOC12H25 punila, što je potvrđeno analizom površine kidanja. Rezultati DSC analize pokazali su da dodatak oba punila ubrzava neizotermnu kristalizaciju PLA matrice i to najznačajnije do 2 % mas. Dodatak MWCNT-COOC12H25 punila zbog dugog alkilnog lanca koji ulazi u matricu znatnije ometa slaganje polimernih lanaca u kristalne forme. Neovisno o vrsti funkcionalnih skupina graftiranih na površini MWCNT tijekom procesa hladne kristalizacije u PLA nanokompozitima stvara se veći udio slabije uređenih struktura nego u čistoj PLA matrici. Toplinska stabilnost najznatnije se poboljšava dodatkom do 2 % mas. punila. Ovakvi rezultati se pripisuju učinku barijere koju stvaraju ugljikove nanocjevčice i dobroj toplinskoj vodljivosti MWCNT. Nije vidljiva znatna razlika u poboljšanju toplinske stabilnosti ovisno o funkcionalnoj skupini graftiranoj na ugljikovu nanocjevčicu. Rezultati ispitivanja električne vodljivosti pokazuju značajno poboljšanje vodljivosti već dodatkom malih količina funkcionaliziranih MWCNT do 0,5 % mas. zbog nastajanja trodimenzionalne vodljive mreže u matrici te istraživani nanokompoziti imaju potencijalnu primjenu za elektrostatsko bojanje i odvođenje elektrostatskog naboja. New trends in research are finding materials who would compete in open market with it's properties, biodegradability and production from renewable sources of energy. Polylactide is one of those materials, and with addition of carbon nanotubes it can compete in the open market. In this study the addition of different quantities of modified carbon nanotubes (MWCNT-COOH; MWCNT-COOC12H25) in PLA was investigated. Samples were prepared by melt mixing in a Brabender plasticoder. Within this study morphology, mechanical properties and mechanism of failure with scanning electron microscopy (SEM) and universal mechanical testing machine were investigated. Thermal properties were investigated by differential scanning analysis and thermal stability was determined by thermogravimetric analysis. Electrical properties were investigated by measuring resistance using four probe method. Results showed the most significant increase of mechanical properties for PLA systems with MWCNT-COOH and MWCNT-COOC12H25 nanofillers up to 2 % wt. PLA nanocomposites (up to 2 % wt) with carbon nanotubes functionalized with long alkyl chains (PLA/MWCNT-COOC12H25) have slightly better properties than systems with MWCNT-COOH due to better distribution of MWCNT-COOC12H25 in PLA matrix, which is confirmed also by fracture surface analysis. DSC results indicate that addition of both fillers accelerates nonisothermal crystallization of PLA matrix and this effect is more pronounced up to 2 % wt. Addition of MWCNT-COOC12H25 nanofiller, due to long alkyl chains that entrance in a matrix, more significantly hinders ordering of polymer chains in the crystalline form. Regardless of the type of grafted functional groups on the surface of MWCNTs, during the cold crystallization a higher proportion of lower-ordered structures than in a pure PLA matrix were created. The most prominent improvement of thermal stability is obtained by the addition of 2% wt of fillers. These results can be attributed to formation of barrier that carbon nanotubes formed and to the very high thermal conductivity of MWCNTs. Depending on the type of functional groups on the carbon nanotubes difference in the improvement of the thermal stability were not observed. The results of electrical conductivity show significant improvement of conductivity with addition of small amounts of functionalized MWCNTs up to 0.5% wt due to the formation of three-dimensional conductive network in the PLA matrix. The investigated nanocomposites have potential use for electrostatic painting and dissipation of electrostatic charge.