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The aim of this work is to prepare polyacrylate emulsions (PA) with the addition of modified titanium dioxide (TiO2) nanoparticles. The modifiers used in this work are the nonionic emulsifier TX-100, the cationic initiator AIBA, the silane AMPTS, and the trisilanol POSS. The results show that particles with a larger hydrodynamic diameter are formed by the addition of modified fillers and that the viscosity of the PA emulsion increases significantly due to the modification of the TiO2 surface. The morphology indicates poorer dispersibility and distribution of the modified fillers in the polymer compared to coating with unmodified fillers. The thermal stability of PA is significantly increased by the addition of modified TiO2 nanoparticles. The results have also shown that the modification of TiO2 with AMPTS increases the UV absorbing ability of TiO2, while the modification with other modifiers enhances the photocatalytic effect of TiO2.

U ovom radu istražen je utjecaj obrade plamenom polipropilena (PP) i termoplastičnih poliolefina s talkom i čađom (TPO) na površinska svojstva i adheziju nanesenog premaza u uvjetima industrijskog procesa robotskog bojenja. Obrada plamenom provedena je na dvije udaljenosti plamena od površine (7,5 cm i 12,5 cm) pri konstantnom protoku zraka i metana te brzini kretanja plamenika. Toplinska postojanost netretiranih uzoraka ispitana je primjenom termogravimetrijske analize (TGA). Promjena toplinskih svojstava prije i nakon obrade plamenom praćena je primjenom diferencijalne pretražne kalorimetrije (DSC). Metodom kontaktnog kuta određena je površinska energija uzoraka prije obrade plamenom te 1 h i 24 h nakon obrade plamenom. Promjene uzrokovane obradom plamenom istražene su ATR – FTIR analizom, a morfološke promjene pretražnim elektronskim mikroskopom (SEM). Nakon nanošenja temeljnog sloja, sloja boje i sloja laka na površinu obrađenih uzoraka određena je adhezija standardnim metodama ISO 2409 i ISO 16925/D25 2018-B. Rezultati su pokazali da TPO uzorci koji sadrže punilo talk i čađu imaju bolju toplinsku postojanost u odnosu na PP. Obrada plamenom utječe na promjenu površinskih karakteristika uzoraka, povećanje slobodne površinske energije i na izgled/strukturu površine. ATR – FTIR analizom utvrđeno je postojanje polarnih skupina na površini nakon obrade plamenom. Svi obojeni uzorci prema zahtjevima normi zadovoljavaju uvjete izvrsne adhezije na međupovršini supstrat/premaz. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna., In this paper, the influence of flame treatment on the surface properties of polypropylene (PP) and thermoplastic polyolefins with talc and carbon black filler (TPO), and adhesion of the applied coating in the conditions of industrial robotic dyeing process were investigated. The flame treatment was carried out at two distances from the flame (7.5 cm and 12.5 cm) at constant air and methane flows as well as speed of the burner. The thermal stability of untreated samples was investigated using thermogravimetric analysis (TGA). The change in thermal properties before and after flame treatment was investigated using differential scanning calorimetry (DSC). Changes of the samples’ surface energy were examined before flame treatment, 1 h and 24 h after flame treatment, by the contact angle method. Qualitative analysis of the surface chemical composition, before and after flame treatment, was performed by ATR – FTIR analysis, and morphological changes by scanning electron microscopy (SEM). After applying the base layer, dye and topcoat on the surface of the treated samples, the adhesion was determined by standard methods ISO 2409 and ISO 16925/D25 2018-B. The results showed that TPO containing talc and carbon black filler have better thermal stability compared to PP. Flame treatment influenced the surface characteristics of the samples, namely the increase in surface free energy and the appearance/structure of the surface. With ATR – FTIR, the existence of polar groups on the surface after flame treatment were determined. According to the standards, all dyed samples met the requirements of excellent adhesion on the substrate/coating interface. This work is licensed under a Creative Commons Attribution 4.0 International License.

Klebsiella pneumoniae is an emerging multidrug-resistant pathogen that can contaminate hospital surfaces in the form of a biofilm which is hard to remove with standard disinfectants. Because of biofilm resistance to conservative disinfectants, the application of new disinfection technologies is becoming more frequent. Ozone gas has antimicrobial activity but there is lack of data on its action against K. pneumoniae biofilm. The aim of this study was to investigate the effects and mechanisms of action of gaseous ozone on the OXA-48-procuding K. pneumoniae biofilm. A 24 h biofilm of K. pneumoniae formed on ceramic tiles was subsequently exposed to different concentrations of ozone during one and two hours to determine the optimal ozone concentration. Afterwards, the total bacteria count, total biomass and oxidative stress levels were monitored. A total of 25 ppm of gaseous ozone was determined to be optimal ozone concentration and caused reduction in total bacteria number in all strains of K. pneumoniae for 2.0 log10 CFU/cm2, followed by reduction in total biomass up to 88.15%. Reactive oxygen species levels significantly increased after the ozone treatment at 182% for the representative K. pneumoniae NCTC 13442 strain. Ozone gas in the concentration of 25 ppm caused significant biofilm reduction but did not completely eradicate the K. pneumoniae biofilm formed on ceramics. In conclusion, ozone gas has great potential to be used as an additional hygiene measure in joint combat against biofilm in hospital environments.

Purpose The purpose of this paper is to prepare stabile emulsions with 0–15% of colloidal silica and high monomer/water ratio and to investigate the influence of silica addition and surface modification on the polyacrylate properties. Design/methodology/approach Improving the properties of the composite can be achieved by optimizing the compatibility between the phases of the composite system with improving the interactions at the matrix/filler interface. Therefore, the silica surface was modified with nonionic emulsifier octylphenol ethoxylate, cationic initiator 2,2'-azobis-(amidinopropane dihydrochloride) and 3-methacryloxypropyltrimethoxysilane and polyacrylate/silica nanocomposites were prepared via in situ emulsion polymerization. Particle size distribution, rheological properties of the emulsions and morphology, thermal properties and mechanical properties of the film prepared from the emulsions were investigated. Findings Polyacrylate/silica systems with unmodified silica, silica modified with nonionic emulsifier and cationic initiator have micrometer, while pure PA matrix and systems with silica modified with silane have nanometer particle sizes. Addition and surface modification of the filler increased emulsion viscosity. Agglomeration of silica particles in composites was reduced with silica surface modification. Silica filler improves thermal stability and tensile strength of polyacrylate. Originality/value This paper provides broad spectrum of information depending on filler surface modification and latex preparation via in situ emulsion polymerization and properties with high amount of filler and monomer/water ratio with the aim that prepared latex is suitable for film formation and final application.

The development of coatings that maintain the attractive natural appearance of wood while providing ultraviolet (UV) protection is extremely important for the widespread use of wood products. In this study, the influence of different types (powder form and aqueous dispersions) of TiO2 in an amount of 1.0 wt% by monomer weight on the properties of environmentally friendly polyacrylate (PA)/TiO2 emulsions prepared by ex situ and in situ polymerization, as well as on the UV-protective properties of the coating films, was investigated. The results showed that the addition of TiO2 significantly affected the particle size distribution of PA and the viscosity of PA varied according to the preparation method. Compared with the ex situ preparation method, in situ polymerization provides better dispersibility of TiO2 nanoparticles in PA coating film, as well as a better UV protection effect and greater transparency of the coating films. Better morphology and transparency of nanocoating films were achieved by adding TiO2 nanofillers in aqueous dispersion as compared to the addition of TiO2 in powder form. An increase in the glass transition temperature during UV exposure associated with cross-linking in the polymer was less pronounced in the in situ-prepared coating films, confirming better UV protection, while the photocatalytic effect of TiO2 was more pronounced in the ex situ-prepared coating films. The results indicate that the method of preparation has a significant influence on the properties of the coating films.

Selektivno lasersko sinteriranje (SLS) jedan je od važnijih postupaka 3D ispisa koji se u današnje vrijeme sve više primjenjuju za dobivanje različitih modela. Najvažniji polimerni materijali koji se upotrebljavaju u tom procesu su poliamidi. Značajan nedostatak tog procesa je velika količina otpadnog polimernog praha. Stoga je cilj ovoga rada bio istražiti utjecaj dodatka nanočestica titanijeva dioksida (TiO2) na toplinska i mehanička svojstva otpadnog poliamidnog praha (PA 2200). U ovom radu pripremljeni su nanokompoziti PA/TiO2 u rasponu masenog udjela punila 1 – 5 %, postupkom zamješavanja punila u talinu polimera u gnjetilici Brabender. Aglomerati nanopunila vidljivi su na SEM mikrografiji 5 %-tnog PA/TiO2 nanokompozita. Rezultati diferencijalne pretražne kalorimetrije (DSC) ukazuju na djelovanje nanočestica TiO2 kao heterogenih nukleacijskih centara. Također, dodatak nanopunila pospješuje stvaranje stabilnijih i uređenijih kristalnih struktura poliamidne matrice. Termogravimetrijskom analizom (TGA) dokazano je da dodatak TiO2 nanopunila povećava temperaturu početka razgradnje PA matrice, to jest poboljšava toplinsku postojanost PA matrice i neznatno povećava vrijednosti toplinske vodljivosti nanokompozita u odnosu na čistu polimernu matricu. Ispitivanjem mehaničkih svojstava uzoraka uočeno je smanjenje vrijednosti sekantnog modula te neznatne promjene naprezanja i istezanja u točki popuštanja s povećanjem udjela punila u nanokompozitu. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna., The PA 2200 waste powder generated during selective laser sintering (SLS) process is an important environmental and economic problem. In order to test and modify the properties of the waste powder, nanocomposites based on polyamide matrix and TiO2 nanoparticles were prepared in this work. Agglomerates of the TiO2 nanofiller are visible on the SEM micrographs for the nanocomposite with 5 wt. % of the nanofiller (Fig. 1). The DSC analysis indicates an increase in crystallization temperature (Tc) by the addition of filler to the polymer matrix and it can be concluded that the TiO2 nanoparticles represent the nucleation centres in the PA matrix (Fig. 2, Table 1). In systems with 4 and 5 wt. % TiO2 crystallization enthalpy (ΔHc) and melting enthalpy (ΔHm) are higher than the values for the polyamide matrix (Table 1), indicating that the nanoparticles promote crystallization of the PA matrix. The results of TG analysis imply a positive effect of the TiO2 nanoparticles on the onset of thermal decomposition, which is most pronounced in the system with 3 wt. % TiO2 (Fig. 3, Table 2). As thermal degradation progresses further, the positive effect of the addition of TiO2 nanoparticles becomes less pronounced and finally becomes negative in the final stages, i.e. TiO2 nanoparticles accelerate the degradation. The thermal conductivity values (λ) are slightly higher for the nanocomposites relative to the pure PA matrix (Fig. 4) due to the formation of a more ordered structure of the polymer matrix by the addition of TiO2 and/or the formation of so-called conductive pathway. The results of the mechanical test indicate that the addition of TiO2 nanofiller decreases the values of the secant modulus (E), while the values of the yield stress (σ2>y2>y2 nanoparticles to the PA 2200 waste powder represents a useful approach for its reuse, thus improving the economic and environmental sustainability of the SLS process. The main disadvantage of the studied systems is the inconsistent mechanical properties at break. In future studies, this problem will be solved with adequate surface modification of TiO2 nanoparticles. This work is licensed under a Creative Commons Attribution 4.0 International License.

The application of emulsion polymerisation for nanocomposite material synthesis is still a problem since it is difficult to achieve emulsion stability and desirable morphology. In this work, the in situ emulsion polymerisation procedure was optimised in order to prepare stable polyacrylate (PA) systems with 15 wt% of modified silica. The surface of the silica was modified with non-ionic emulsifier (NE), cationic initiator 2, 2'-azobis (2-amidinopropane) dihydrochloride (AIBA) and 3-methacryloxypropyltrimethoxysilane (MPS). The adsorption conditions, the influence of monomer mode addition, the rate of pre-emulsion addition, monomer/water ratio, the pH and the amount of anionic emulsifier (SDS) on polyacrylate/silica emulsion stability were investigated. The results showed that the most significant influence on emulsion stability have the amount of anionic emulsifier and silica surface modification. This work contains practical knowledge regarding adsorption of non-ionic emulsifier, emulsion stability, filler surface modification and in situ emulsion polymerisation with high amount of modified silica (15 wt%) and monomer/water ratio 70/100.

Pure and doped vanadia (VO2, V0.98Zr0.02O2, V0.98Ce0.02O2) samples were prepared by wet chemistry synthesis from vanadyl glycolate intermediate phase and tape casted into films. Combining in-operando grazing incidence synchrotron X-ray diffraction and Raman spectroscopy, we studied the structural evolution of the films under isothermal conditions. The setup allowed assessment of the thermochromic functionality with continuous monitoring of the monoclinic to tetragonal transition in pure and doped vanadia phases, responsible for the transmission and reflection of light in the infrared part of the solar spectrum. The materials characterisation by X-ray diffraction beamline (MCX) goniometer demonstrated ideal performance, combining flexible geometry, high resolution, and the potential to accommodate the multi-channel equipment for in-operando characterisation. This method proved viable for evaluating the relevant structural and physical, and thereof functional properties of these systems. We revealed that dopants reduce the transition temperature by 5 &deg, C on average. The synthetic route of the films was held responsible for the observed phase separation. The more favourable behaviour of cerium-doped sample was attributed to cerium alkoxide behaviour. In addition, structural, microstructural, thermal, and spectroscopic characterisation on powder samples was performed to gain more insight into the development of the phases that are responsible for thermochromic features in a broader range of doping ratios. The influence of the dopants on the extent of the thermochromic transition (transmission to reflection hysteresis) was also evaluated using (micro) structural, thermal and spectroscopic methods of powder samples. Characterisations showed that zirconium doping in 2, 4, and 6 mol% significantly influenced the phase composition and morphology of the precursor. Vanadium oxides other than VO2 can easily crystallise, however, a thermal treatment regime that allowed crystallisation of VO2 as a single phase was established.

The rapid development of nanotechnology allowed implementation of metal oxide nanoparticles in coatings and protection of coatings without significant influence on transparency. To avoid negative impact on coating properties it is important that nanoparticles are uniformly dispersed and that the emulsion of nanoparticles is compatible with the components in coating. In this article the effect of TiO2 and ZnO nanoparticles on properties of polyacrylate waterborne coating and on stability of coating films exposed to outdoor conditions are studied. The results of this research show that ZnO nanoparticles reduce flow time of waterborne polyacrylate coating and increase pH. Furthermore, TiO2 and ZnO nanoparticles increase colour stability of waterborne polyacrylate coating. Moreover TiO2 nanoparticles have a great impact on increase of Tg, and ZnO nanoparticles on decrease of elongation and thereby on increase of brittleness of waterborne polyacrylate coating.

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.

In this article, isothermal crystallization kinetic of the linear hydroxyl polyester urethane (PUR), as well as influence of amorphous silica nanofiller, was investigated. With the aim to investigate the influence of filler surface modification on the crystallization process of polyurethane matrix, nonmodified silica, as well as silica modified with methacrylsilane and octylsilane, were used as fillers for PUR composite preparation. The crystallization kinetics depending on temperature of the isothermal crystallization and volume fraction of filler by using differential scanning calorimetry (DSC) were investigated. The measurements at temperatures 7, 12, and 17°C for PUR and composites with 0.5, 1, 2, and 4 vol % of filler were done. Kinetic parameters of the isothermal crystallization n and K were determined according to Avrami model. Melting of the isothermally crystallized samples was also investigated. Results of the research indicate that by increasing the isothermal crystallization temperature, the crystallization rate of the PUR soft phase decreases and that the perfection of the crystallites is improved. By addition of all fillers up to ≈1 vol %, the crystallization rate increases ; however, addition of a higher amount of the filler significantly decreases the crystallization rate. It was found that surface modification can significantly affect crystallization rate and that the nucleation efficiency of silica increases in the following order: methacrylsilane-modified silica < nonmodified silica < octylsilane-modified silica

Morphological, mechanical, and Fourier transform infrared dichroic investigations were performed on neat polyurethane (PU) polymer matrix and PU+CaCO3 nanocomposite thin films to determine how the nanofiller influenced the mechanical properties. The measurements were performed on strips that were cut from the prepared films in parallel and perpendicular directions with respect to the direction of film preparation. Optical microscopy of PU and the PU+CaCO3 nanocomposite revealed the strain-induced transition from a continuous spherulitic morphology to a fiberlike structure. The stress–strain behavior of the neat PU and PU+CaCO3 nanocomposite films showed significant differences at large strain regimes. The experimental results suggest that the mechanical properties were strongly related to the orientational behavior of the separated phases. The orientation of the hard and soft segments was analyzed by the orientation function calculated from the IR absorbances. A correlation between the orientations of segments, tensile properties, and hardness of the investigated polymer films was established. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

In this study influence of monomer ratio, butyl acrylate (BA), and methyl methacrylate (MMA) as well as silica nanofiller morphology (pyrogenic and colloidal) and concentration on the emulsion particle size distribution and properties of polyacrylate film (PA) synthesized by in situ emulsion polymerization were investigated. The ratios of the monomers BA/MMA were 100/0, 70/30, 50/50, 30/70, 0/100 and the filler concentration 0–10.0 mass%. PA nanocomposite films were characterized by using thermogravimetric analysis, differential scanning calorimetry, and tensile test. Research has shown that monomer ratio has significant influence on glass transition temperature (Tg). The addition of both types of silica filler, pyrogenic and colloidal, has no effect on Tg. Thermogravimetric analysis showed that systems with higher BA fraction have better thermal stability than systems with higher MMA fraction. Addition of the both type of silica nanofiller enhanced thermal stability of PAs, however, systems with colloidal silica are more stable. Pyrogenic silica and higher amounts of colloidal silica nanofiller increased PA emulsion particle size up to several micrometers. Addition of higher amounts of colloidal silica improved mechanical properties compared to the neat PA matrix. POLYM. ENG. SCI., 53:2292–2298, 2013. © 2013 Society of Plastics Engineers

Adhezivi (ljepila) su nemetalne tvari koje mogu spajati različita tijela kombiniranim djelovanjem prijanjanja na dodirne površine (adhezija) i vlastite unutrašnje čvrstoće (kohezije), ne mijenjajući bitno strukturu tih tijela. Osim polimerne komponente i ostalih aditiva, u konačnoj formulaciji velikog broja adheziva nalaze se kapljeviti mediji, različita organska otapala ili voda. U okviru ovog rada provedena je analiza četiri različita adheziva, dva na osnovi organskog otapala metilen–klorida i dva na osnovi vode. Ispitivana im je kontaktna ljepljivost u određenom vremenu što je praćeno na supstratu PUR pjena s namjerom da se definira optimalno vrijeme sušenja i maksimalno otvoreno vrijeme. Krutim uzorcima adheziva određivana su toplinska svojstva tehnikom diferencijalne pretražne kalorimetrije (DSC) te rastezna svojstva adheziva na bazi vode AV-1 i AV-. Također je istraživan utjecaj pH vrijednosti na kontaktnu ljepivost adheziva na bazi vode. Za tu namjenu istraživana je kontaktna ljepljivost baze vodenog adheziva te sustava kojima je pH vrijednost snižena dodatkom glicina na vrijednosti: pH=9.3, pH=9.0 i pH=8.4, te im je praćena stabilnost u ubrzanim uvjetima stajanja. Rezultati kontaktne ljepljivosti nakon određenog vremena sušenja i kidanja spojeva pokazali su da spojevi s adhezivima na osnovi metilen-klorida popuštaju kohezijski po substratu PUR pjene, dok spojevi s adhezivima na osnovi vode popuštaju kohezijski u sloju adheziva. Mehanička svojstva filmova polikloroprenskih adheziva na osnovi vode mogu se mijenjati odabirom polimernih osnova s različitim udjelima kristalne faze. Primjenske karakteristike polikloroprenskih adheziva na osnovi vode mogu se poboljšati sniženjem pH adheziva. Kao najbolji dodatak za ovu namjenu pokazala se otopina glicina. Ispitivanje formuliranih adheziva u ubrzanim uvjetima stajanja pokazuje odličnu stabilnost za sve uzorke adheziva.

Obzirom da su polimeri građeni uglavnom od ugljika i vodika, zapaljivi su, a na temperaturi iznad 300°C podliježu nagloj razgradnji. Gorenje polimera je nepoželjno, te se dodavanjem posebnih aditiva, usporavala gorenja, direktno djeluje na ograničavanje gorenja i širenje gorenja. Polistiren visoke udarne žilavosti (HIPS) je dvofazni sustav fino dispergiranih čestica kaučuka, najčešće polibutadiena, u polistirenu. HIPS ima vrlo široku primjenu kao materijal u električnim uređajima, elektronskoj industriji i kao građevinski materijal, gdje se zahtjeva negorivost, te mu se u tu svrhu dodaju usporavala gorenja, najčešće bromirana. Zbog problema promjene boje HIPS-a (Polistiren VM 40902) u primjeni, za koji se pretpostavlja da uzrokuje usporavalo gorenja na osnovi dekabromodifenil oksida (DBDO), cilj ovoga rada bio je ispitati komercijalne zamjenske koncentrate za smanjenje gorivosti (B, C, i D) koji nisu na osnovi DBDO. Eksperimentalni dio uključuje pripravu ispitnih tijela prešanjem granulata dobivenih ekstruzijom. Dobiveni uzorci analizirani su diferencijalnom pretražnom kalorimetrijom, termogravimetrijskom analizom i skenirajućom elektronskom mikroskopijom (SEM), a određena su i mehanička svojstva (rastezna svojstva i udarna žilavost). Gorivost je ispitana metodom užarene žice, određivanjem graničnog indeksa kisika, te vertikalnim testom gorenja. Koncentrati za usporavanje gorivosti povećavaju početnu temperaturu razgradnje HIPS-a, ali mu smanjuju toplinsku stabilnost na višim temperaturama. Rezultati određivanja gorivosti pokazali su da dodatkom svih koncentrata, HIPS zadovoljava uvjete po kojima se može svrstati u samogasivi tip materijala. Koncentrati za smanjenje gorivosti ne mijenjaju značajno ili povećavaju značajke pri malim deformacijama (E i σy) i prekidnu čvrstoću (σb), međutim smanjuju prekidno istezanje (εb) i udarnu žilavost. Kao najbolja zamjena za komercijalni koncentrat za smanjenje gorivosti je koncentrat B.

In this article, the influence of fumed silica nanofiller on the structure and properties of segmented polyurethane elastomer (PUR) was investigated. In order to investigate the interactions at the filler–matrix interface, nonmodified and commercially modified fillers (with methacrylsilane and octylsilane) were used. The PUR composites with 1.0, 2.0, 4.0, 6.0, and 9.0 vol % of all fillers were prepared by solution casting method. Surface free energy of the fillers and polymer matrix was determined using contact angle measurements with different testing liquids. Change in morphology was analyzed using optical polarization microscopy and distribution of the filler in polymer matrix using scanning electron microscopy. The influences of silica fillers on mechanical and thermal properties of PUR were investigated. Results showed that surface treatment of silica filler with methacrylsilane and octylsilane reduces the agglomeration of particles that improves dispersion at microlevel. Addition of all fillers disrupts spherulite morphology and decreases crystallinity of the PUR matrix. Nonmodified silica nanofiller has the least pronounced influence on spherulite morphology and the lowest influence on polyurethane crystallinity and thus the best mechanical properties. Surface modification of silica with octylsilane has less influence on polyurethane crystallinity and on decreasing of mechanical properties than modification with methacrylsilane. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Mechanical and morphological properties of composites containing styrene—acrylonitrile (SAN) copolymer, ethylene— propylene—diene (EPDM) polymer, and different types of precipitated calcium carbonate (PCC) were investigated and their properties were analyzed in regard to PCC surface properties and the way of sample preparation (with or without use of a masterbatch (MB)). Contact angles of test liquids on PCC samples were measured in order to determine surface free energies of filler and to predict strength of filler—polymer interactions. Filler—polymer interactions play a significant role in determining preferential localization of the filler in the composite. The tensile and impact strength results of the composites without the MB show much higher values than composites prepared with the MB. Significant decrease of tensile strength is observed for the samples prepared with the MB due to change in morphology, which is elongated dispersed EPDM particles in SAN matrix, compared to the samples prepared without the MB that have droplet morphology.

Polyurethane (PU) and poly(vinyl acetate) (PVAc) are partially miscible polymers. The aim of this study was to investigate the influence of untreated and surface pretreated calcium carbonate (CaCO3) on the interphase properties of PU/PVAc polymer blends with possible compatibilization effects when the conditions of effective adhesion are achieved. With the aim to modify interface between filler and matrices, CaCO3 was pretreated by grafting PVAc on the filler surface using 60 Co c-ray irradiation polymerization of vinyl acetate. A series of the PU/PVAc blends without and with the addition of CaCO3 were prepared using a Brabender plasticorder at 1408C. Surface characterization of the PU and PVAc polymers as well as the untreated and surface pretreated CaCO3 fillers was carried out by determination of the surface free energy. The adhesion between CaCO3 and phases in the polymer blends was predicted on the basis of the calculated adhesion parameters (interfacial free energy, spreading coefficient and work of adhesion) obtained from the surface free energy of components. Thermal and mechanical properties were investigated by tensile strength measurements and differential scanning calorimetry (DSC). The adhesion parameters were correlated with the mechanical and thermal properties as well as phase morphology observations. POLYM. ENG. SCI., 48:1931–1938, 2008. a 2008 Society of Plastics Engineers

Interface in particulate filled polymer systems is the central place that determines the behaviour of the composites and polymer blends. In this paper we have made the surface free energy measurements and calculations of adhesion parameters at the interface in poly(vinyl acetate) (PVAc) and polyurethane (PU) composites as well as in styrene acrylonitrile / ethylene propylene diene monomer (SAN/EPDM) blends filled with calcium carbonate (CaCO3) nanofillers. We have investigated the effects of filler surface pre-treatment with stearic acid and/or silane on the interface and related it to the properties. The effective adhesion in the particular composites and blends was followed by optimal adhesion parameters at the interface i.e. by the minimal interfacial energy and nanofillers situated at the interface. The models used for prediction of the filler location in regard to the interface showed a good correlation with improvement of the properties for the systems that are close to the conditions of the effective adhesion.

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.

Poly(vinyl acetate) (PVAc) composites were prepared by different approaches, namely (i) by mechanical mixing of untreated CaCO3 and PVAc, (ii) by mechanical mixing of CaCO3 pre-treated by irradiation polymerization in the presence of vinyl acetate, and (iii) by in situ emulsion polymerization of VAc in the presence of untreated CaCO3 nanofiller. The effects of nanoparticle pre-treatment and different approaches of preparation were correlated with changes in morphology and mechanical properties of PVAc composites using scanning electron microscopy and tensile tests. Untreated CaCO3 nanoparticles in the composite prepared by mechanical mixing provided strong interactions with the PVAc matrix. On the other hand, CaCO3 pre-treated nanoparticles decreased the interfacial interactions. For composites prepared by in situ polymerization a better dispersion of encapsulated nanoparticles was achieved and, as a result, a significant improvement of composite strength was observed. Interfacial interactions in nanocomposites can be changed by filler pre-treatment or by a suitable way of nanocomposite preparation.

In this work we have investigated the effects of CaCO3 nanofiller pretreatment on the properties of polyurethane (PU) composites prepared by a mixing procedure. The aim was to enhance interactions at the matrix/filler interface and to improve the distribution of the filler in the polyurethane matrix. CaCO3 nanofiller was treated with two different functional trialkoxysilanes, viz. γ-aminopropyltriethoxysilane (AMPTES) and γ-glycidoxypropyltrimethoxysilane (GPTMS). Fourier transform IR spectroscopy of the pre-treated CaCO3 surface indicates that AMPTES formed a high-molecular-weight ladder-type structure on the CaCO3 surface, while GPTMS was adsorbed in the form of a lower-molecular-weight oligomeric structure. Increased ultimate tensile strength and elongation were obtained for PU + CaCO3 nanocomposites with silane pre-treated filler. This can be explained as the consequence of better stress transfer through the composite, observed on scanning electron micrographs, due to an improved adhesion between PU matrix and silane-treated fillers. The reinforcement effect is more pronounced for PU composites with aminosilane-treated CaCO3 filler in comparison to filler treated with glycidoxysilane.

Primjena naprednih tehnologija obrade voda kao što su tlačne membranske tehnologije postaje sve intenzivnija zbog sve strožih regulativa vezanih za emisiju efluenata otpadnih voda kao i ekonomskim interesom za njihovom ponovnom upotrebom. Postrojenja za termičku obradu nusproizvoda životinjskog podrijetla, koriste znatne količine vode za pranje i održavanje higijenskih uvjeta unutar postrojenja, te tako proizvode otpadnu vodu opterećenu mikroorganizmima, organskim tvarima i povećanim sadržajem soli. Oporaba takve vrste otpadne vode moguća je primjenom tankoslojnih kompozitnih ultrafiltracijskih (UF), nanofiltracijskih (NF) i reverzno osmotskih (RO) membrana koje omogućavaju učinkovito uklanjanje mikroorganizama, suspendiranih čestica i mutnoće, te smanjenje sadržaja organskih tvari, soli i nutrijenata. U ovom radu ispitane su tri UF (MW, GM i CQ), dvije NF (NF270 i NF90) i jedna RO (XLE) membrana u dvostupanjskom procesu obrade efluenta nakon biološke obrade u šaržnom bioreaktoru (SBR). U prvom stupnju korištene su UF, a u drugom stupnju NF i RO membrane. Ispitane su membranske performanse, a separacijska učinkovitost je praćena analizom struje permeata mjerenjem ključnih parametara električne provodnosti, mutnoće, pH, sadržaja ugljika, nitrita, nitrata i fosfora u svim koracima procesa. Praćena je promjena protoka uslijed blokiranja membrane te ispitano čišćenje membrana. S obzirom na separacijsku sposobnost, permeabilnst te povrat fluksa nakon čišćenja, odabrane su membrane s najboljim performansama. Za prvi stupanj najboljom se pokazala MW, a za drugi NF90 membrana.

U ovom radu provedena je sinteza čestica kalcijevog karbonata korištenjem produkata biokatalitičke hidrolize uree uz enzim ureaze. Ispitana je kinetika hidrolize uree uz enzim ureazu te je promatran utjecaj kalcijevih (Ca2+) iona na aktivnost enzima. Reakcije su provedene u tri medija: 4-(2-hidroksietil)-1- piperazinil- etansulfonskoj kiselini (HEPES pufer ; c (HEPES) = 0, 1 M, pH 7), trietanolamin puferu (c (TEA) = 0, 1 M, pH 7) i redestiliranoj vodi, pri dvije temperature, T = 30 °C i T = 40 °C. Kinetika reakcije opisana je jednosupstratnom Michaelis – Menten kinetikom s nekompetitivnom inhibicijom kalcijevim ionima. Razvijen je matematički model procesa koji je validiran provođenjem reakcije u kotlastom reaktoru uz stalno miješanje magnetskom miješalicom. Sinteza čestica provedena je dodavanjem kalcijevog klorida u otopinu uree, uz dodatak enzima ureaze. Reakcijom kalcijevih iona s produktima hidrolize uree istaložene su čestice kalcijevog karbonata koje su potom karakterizirane pomoću pretražnog elektronskog mikroskopa i rendgenskog difraktometra. Pokazano je da brzina hidrolize uree uz enzim ureazu utječe na veličinu nanočestica. Za pripremu hibridnih materijala je u ovom radu korišten sol – gel postupak uz prekursor 3- glicildiloksipropiltrimetoksisilan (GLYMO) i cinkov-oksid (ZnO) te klorovodična kiselina kao katalizator. Homogenizirane smjese izlijevanje su u teflonske posudice, a zatim su uzorci folija (polietilen, polistiren, poli(etilen- tereftalat)) uranjani brzinom od 1 mm s-1. Nakon geliranja i dodatnog učvršćivanja uzorci su karakterizirani SEM-EDX metodom. Analiza je pokazala neravnomjerne prevlake i time ukazala na potrebu homogenizacije sola pomoću ultrazvučne sonde. EDX metoda ukazuje na prisustvo Si i na silikatno umrežavanje uz Zn.

Suvremeni način života podrazumijeva korištenje prijenosnih uređaja, poput mobitela i prijenosnih računala, koji zahtijevaju prijenosni i dugotrajni izvor energije - baterije. U stalnoj potrebi za manjim, tanjim, lakšim, sigurnijim i ekološki prihvatljivijim uređajima, upravo vrsta elektrolita u baterijama ima važnu ulogu. U tom smislu se dosta istražuju kruti polimerni elektroliti (eng. Solid Polymer Electrolytes, SPE), a poli(etilen-oksid) (PEO) je praktički jedini prihvatljivi polimer za tu svrhu. Visoki stupanj kristalnosti PEO-a negativno utječe na njegovu ionsku provodnost pri sobnoj temperaturi budući da se ionska provodnost odvija primarno u amorfnoj fazi. Stoga je smanjenje udjela kristalne, odnosno povećanje udjela amorfne faze, ključ za poboljšanje ionske provodnosti polimernih elektrolita na osnovi PEO-a. Smanjenje stupnja kristalnosti i posljedično poboljšanje elektrokemijskih svojstava (ionske provodnosti) polimernih elektrolita na osnovi PEO-a moguće je postići dodatkom anorganskih nanočestica u matricu PEO-u. Utjecaj dodatka litijevog montmorilonita (LiMMT) kao anorganskih nanočestica na kristalnost PEO-a ispitan je primjenom infracrvene spektroskopije s Fourierovom transformacijom (FTIR) i diferencijalne pretražne kalorimetrije (DSC). U kristalnom stanju makromolekule PEO-a zauzimaju spiralnu ili helikoidalnu konformaciju, a FTIR analiza ukazuje da se u kompozitima s LiMMT-om narušava spiralna struktura makromolekula PEO- a. Diferencijalnom pretražnom kalorimetrijom (DSC) potvrđeno je da dodatak LiMMT-a smanjuje kristalnost PEO-a. Ionska provodnost PEO/LiMMT kompozita određena je elektrokemijskom impedancijskom spektroskopijom (EIS). EIS pokazuje značajan porast ionske provodnosti u PEO/LiMMT kompozitima pri sobnoj temperaturi u odnosu na izvorni PEO.