International Journal of Biological Macromolecules, Jul 1, 2018
Present study reports synthesis and physico-chemical evaluation of hydrophobically modified pecti... more Present study reports synthesis and physico-chemical evaluation of hydrophobically modified pectin derivatives, obtained by reacting of pectin with di-acyl chlorides (glutaryl and sebacoyl chloride). Depending on length of the inserted carbon chains, the acylation resulted in possible formation of mono-grafted (isolated chains) and bi-grafted (chemical gels) structures. The structural features of obtained derivatives were investigated using FTIR spectroscopy, confirming the successful synthesis. The concentrated aqueous solutions of modified pectin showed interesting rheological properties, having lower values of apparent viscosity compared to neat pectin. Since the GPC analysis indicated that no degradation occurred, the viscosity decrease was explained by more heterogeneous organization within modified pectin solutions (microparticles together with sticky polymer entanglement). A shift in particle size distribution proved that proposed modifications also affected pectin solution properties in diluted regime. The modified samples turned to be more sensible to thermal degradation than neat pectin, whereby the increasing size of flexible acyl chains attached to a polymer backbone reduced the glass transition temperature. The hydrophobicity of obtained derivatives was evaluated by sessile drop and du Nouy ring methods. It was found that acylation enhanced hydrophobicity of the pectin molecule, while hydrophobically associative character turned to be inconsistent in aqueous and non-aqueous environment.
Journal of materials chemistry. A, Materials for energy and sustainability, 2016
Mimicking the excellence of natural materials presents an attractive route in the synthesis of ad... more Mimicking the excellence of natural materials presents an attractive route in the synthesis of advanced functional materials.
Environmental Science and Pollution Research, 2019
Nowadays, the extensive use of pesticides in crops production puts a significant challenge to min... more Nowadays, the extensive use of pesticides in crops production puts a significant challenge to minimize its side effects along with safe production, storage, and after-use treatment. This paper reports results related to the emission of certain pesticide formulations through the PET containers, as well as, their mitigation to the PET containers during their storage. The influence of storage time on cypermethrin migration to and through the PET was studied in short-term Collaborative International Pesticides Analytical Council test lasting up to 30 days. The PET containers were filled with pure xylene and pesticide formulations, where the amount of active substance, cypermethrin (CY), varied from 5 to 20 wt%, while the amount of emulsifier was kept constant. The results indicate that pesticide formulations diffuse to PET containers with an average increase of its initial mass up to 1.5%. The most intensive diffusion is in the first 24 months of storage, after its rate significantly decreases. It should be noted that the diffusion studied pesticide formulations are also very dependent on CY concentration. Besides the migration to the PET containers, it was also found that pesticide formulation was emitted through the PET containers in the first 17 to 24 months of storage depending on CY concentration. Emission rates were also dependent on CY concentration and were in the range of 15.3 to 38.0 mg/month•container. The emission through the PET containers was successfully predicted using artificial neural networks with R 2 = 0.94 and the mean absolute percentage error (MAPE) of only 6.2% on testing.
During the last two decades, interest in bio-based polymers, especially in bio-based composite ma... more During the last two decades, interest in bio-based polymers, especially in bio-based composite materials, has grown as a result of environmental concerns. In this paper new composites obtained from fully bio-based unsaturated polyester resin (UPR) and waste poly(ethylene terephthalate) (PET) were studied for the first time. The composites were prepared by crosslinking the UPR in the presence of functionalized PET particles (3, 6 and 9 wt %), using dimethyl itaconate as reactive diluent. The results showed that the incorporation of the PET particles led to the increase in mechanical properties. However, higher PET loading caused a decrease in the mechanical properties of the composites because of the PET particle agglomeration.
The design of complex polymeric materials with predefined task-specific properties meets challeng... more The design of complex polymeric materials with predefined task-specific properties meets challenging issues: to establish synthesis-structure-properties relationship, as well as to understand the arrangement and interactions of the involved components. Hybrid networks of protein (casein) and polyelectrolyte (poly(methacrylic acid)) were synthesized and their swelling, dynamic-mechanical and morphological properties were investigated as functions of the neutralization degree of methacrylic acid and the concentrations of caseinate and crosslinker. The domination of different interactions between components led to diverse forms of casein macromoleculesfrom micelles to unfold chains. That resulted in very different structures and thereby properties of derived hybrid networks: from porous unswellable to highly swellable and reinforced ones. A great opportunity to easily modulate the final characteristics of the reported hybrid system to fit the need of specific application just through the change of one synthesis parameter was thereby demonstrated.
Synthesis of high-performance anticorrosive coatings obtained from alkyd resins (ARs) based on wa... more Synthesis of high-performance anticorrosive coatings obtained from alkyd resins (ARs) based on waste poly(ethylene terephthalate) (PET) glycolyzates is presented. PET glycolyzates, synthesized by catalytic depolymerization with trimethylolpropane (TMP) and dipropylene glycol (DPG), were used as replacement of part of the polyhydroxylic component during the ARs synthesis. The obtained glycolyzates and ARs were analyzed using FT-IR and 1 HNMR spectroscopy and acid, iodine, and hydroxyl value were determined. Thickness, adhesion, swelling, corrosion, spraying and layering of the synthesized ARs, as well as alkyd coating film were determined in accordance with SRPS EN ISO standards. ARs were produced in high yields and FT-IR and 1 NMR analysis results confirmed assumed structures. All synthesized ARs show good elasticity, flexibility, adhesion and the gloss values are greater than 85 %, and the alkyd coating films based on AR1 and AR3 showed best corrosion results. The most effective dryer catalyst combination was 0.5 wt.% Ca, 0.03 wt.%, Co and 0.45 wt.% Zr.
Abstract Electricity generation using carbon-based fuels is responsible for a large fraction of c... more Abstract Electricity generation using carbon-based fuels is responsible for a large fraction of carbon dioxide emissions worldwide. In Serbia, 70% of the electricity is produced from coal-fired power plants. The aim of this investigation was to identify the retrofitting opportunities to reduce the carbon intensity of power generation. Resource Efficient and Cleaner Production assessment was performed in a coal thermal power plant of the public company “Thermal Power Plants Nikola Tesla”, which operates within the Electric Power Industry of Serbia. Assessment of the thermal power plant operation was supported by experimentally measured data (fresh water pressures and temperatures, steam temperatures and pressures, condensing pressure, water flowrate, make-up water flowrate, steam flowrate, coal composition, emissions, etc), emission factor determinations and by using data obtained during unit balancing and simulation of the system's performance. The data collected and analyzed during power plant operation were used for the development of a new general approach with comprehensive analysis of the system, using the following plant eco-efficiency indicators: energy consumption, climate change, acidification, and waste generation. Indicators were used to present decoupling after implementation of the described measures. The analysis of two units showed that the nominal power could be increased by 60 MWe, with an increase of the unit gross efficiency of 0.4%, and a reduction of coal, water and electricity consumption. The implementation of RECP measures in this study enabled analysis of the overall performance of the system as evidenced by the eco-efficiency indicators: energy consumption (decreased by 3%), CO2 emission (decreased by 3%), and SO2 emission (decreased by 39%). Consequently, it may be concluded that the proposed RECP approach, tested on thermal power plants, and presented as eco-efficiency indicators show that the described methodology may be successfully implemented in the energy sector and for the improvement in power plants.
Journal of Materials Science: Materials in Electronics, 2015
Abstract Polymers are very attractive as thin films in emerging reel-to-reel manufacturing or as ... more Abstract Polymers are very attractive as thin films in emerging reel-to-reel manufacturing or as spin coated from liquid form in a quick and low cost process in standard microfabrication processes. There is a wide selection of materials available with many different thermal, electrical, and mechanical properties. With continuous growth in consumer electronics and sensors sectors, the range of potential application fields is further diversifying and integration of MEMS modules, as well as delivering IC functionality in thin foil-like packaging with proven reliability and reduction in cost is increasingly required. Furthermore, increased volume and decentralisation of testing within medical diagnostics field worldwide (IVD Point of Care and Patient Self Testing trends) require low cost solutions for disposable test cartridges and other supporting consumables. In majority of the emerging medical applications, integrated, low cost sensors need to operate in liquid environment, often rendering the use of standard Si-based solutions inadequate and costly. Polymer-based microcantilevers, realised by standard surface microfabrication techniques, were chosen for this study as the alternative approach to Si-based MEMS. Cantilevers are well understood microstructures and so provide an excellent vehicle for assessing both thermo-mechanical properties of polymers as MEMS materials and their potential for die-level packaging and integration into miniaturized systems. Due to the nature of processes involved and their thermal budget, substitution of Si substrate with e.g. flexible substrates or polymer films is foreseen in the near future. Fabricated cantilever beams consist of various combinations of thin metal/polymer and polymer/polymer films. Polyimides, as structural material, have been selected for this study due to inherently good mechanical properties, good chemical resistance, low dielectric constant and high thermal stability.
A new perspective for mass production of alkyd resins from multifunctional glycolyzates obtained ... more A new perspective for mass production of alkyd resins from multifunctional glycolyzates obtained from waste PET – a step up to greener production and excellent applicative properties.
Non-isothermal thermogravimetry was performed in a dynamic nitrogen atmosphere, on a series of po... more Non-isothermal thermogravimetry was performed in a dynamic nitrogen atmosphere, on a series of poly(di-n-propyl itaconates) (PDnPI) and poly(di-iso-propyl itaconates) (PDiPI) which had been prepared in the presence of various amounts of the chain transfer agent n-dodecyl mercaptan (DDM). Differential thermogravimetry (DTG) showed that both polymers degraded in two stages. The DTG curve of PDnP1 had a large first peak followed by a smaller shoulder, whereas the DTG curve of PDiPI was composed of two peaks of almost equal heights. The addition of DDM during the polymerisations in both cases resulted in a similar decrease in the relative area of the first peak.
Itaconic acid, IA (C5H6O4), was investigated as a potential flocculant for the aqueous processing... more Itaconic acid, IA (C5H6O4), was investigated as a potential flocculant for the aqueous processing of alumina powders. The adsorption of IA, as a function of its concentration and pH value of the solution, onto the alumina surface was studied by the solution depletion method. The stability of the suspensions in the presence of itaconic acid was evaluated in light of the surface charge of the alumina powder used, the degree of dissociation of IA, as well as the sedimentation behavior and rheology of the suspensions. It was found that the adsorption process is extremely pH dependent; the maximum adsorption of IA onto alumina surface occurring at a pH close to the value of the first IA dissociation constant, pKa1. Also, IA does not influence the value of the point of zero charge of alumina. It was shown that IA represents an efficient flocculant for concentrated acidic alumina suspensions.
International Journal of Polymeric Materials, 2012
Biodegradable crosslinked biopolyesters and interpenetrating networks (IPN) were prepared with po... more Biodegradable crosslinked biopolyesters and interpenetrating networks (IPN) were prepared with poly(cardanol fumarate) (MCFR) and poly(castor oil fumarate) (CFR). Addition polymerization and crosslinking with styrene-free vinyl monomers, vinyl acetate (VA) and n-vinyl pyrrolidone (VP) was adopted to prepare these materials. The IPNs have higher thermal stability and mechanical properties in comparison with the crosslinked biopolyesters. The improved characteristics of IPNs are
Eight selected trace elements, which are generally included in regulations, were analyzed in 23 t... more Eight selected trace elements, which are generally included in regulations, were analyzed in 23 types of bottled waters. Ten mineral and seven spring bottled waters were from the Serbian market and six mineral bottled waters were obtained in different EU countries. For the purpose of comparison, selected tap waters were also analyzed. Inductively coupled plasma mass spectrometry (ICP-MS) was used for the analysis of trace elements (arsenic, cadmium, copper, manganese, nickel, lead and antimony). Results were compared with the Serbian regulations for bottled water, EU regulations and guideline values set by the World Health Organization for drinking water. With few exceptions, the trace element levels of most bottled waters were below the guideline values. However, a higher content of antimony was observed in waters from polyethylene terephthalate (PET) containers, indicating a potential leaching of this element from the plastic packaging.
The oxidative thermal degradation of poly(2-chloroethyl methacrylate) (PCEMA) was studied in the ... more The oxidative thermal degradation of poly(2-chloroethyl methacrylate) (PCEMA) was studied in the presence of the following commercial antioxidants: CHIMASSORB 119 (CH 119) and CHIMASSORB 944 (CH 944), both based on amines, and a mixture of IRGANOX 1010, a phenol derivative, and IRGAPHOS 168, a phosphite (mass ratio 1:1), by the thermogravimetric (TG) method. On the basis of the obtained results, the characteristic temperatures of 10% mass loss, Tio%, the shape of the differential TG (DTG) curves and mean values of the thermal degradation activation energy, Ea, it was concluded that the commercial photostabilisers CH 119 and CH 944 could not successfully stabilize the thermal degradation of PCEMA, while in the case of the presence of the antioxidant mixture IRGANOX 1010 and IRGAPHOS 168 (1:1) slight stabilizing effects were observed.
The non-oxidative thermal degradation of poly(iso-butyl methacrylate) and poly(sec-butyl methacry... more The non-oxidative thermal degradation of poly(iso-butyl methacrylate) and poly(sec-butyl methacrylate) was investigated by studying changes in the polymer residue. Due to the different number of β-hydrogens in their ester substituents, these two polymeric isomers behave differently when subjected to elevated temperatures. Poly(iso-butyl methacrylate) degrades quantitatively by depolymerisation with zip lengths of the same order of magnitude as those of poly(methyl methacrylate). Poly(sec-butyl methacrylate) degrades by a combined degradation mechanism of depolymerisation and de-esterification. De-esterification becomes a significant thermolysis route at temperatures higher than 240 ºC.
The aim of this paper is to present image analysis as a useful technique for fast, reliable and n... more The aim of this paper is to present image analysis as a useful technique for fast, reliable and non-destructive detection of dimensional and structural changes in polymers. The possibility of applying image analysis was demonstrated in the case of solvent-induced crystallization of poly(ethylene terephthalate) (PET) containers filled with commonly used organic solvents: chlorobenzene, isophorone, xylene, Espesol, Shellsol A 100, Solvesso 150, propylene glycol, glycerin and water and subjected to the storage stability test at 54 °C for 14 days (CIPAC 1-MT 46.1.3). In addition, the obtained results were analyzed using one-step analysis of variance (ANOVA) combined with the Duncan's statistical test (p<0.05). According to the achieved results, three main impacts of the presented paper could be distinguished: 1) dimensional and transparency changes could be precisely followed by image analysis in both following cases: for small changes in water, as well as for significant ones in chlorobenzene; 2) a correlation between the changes in the degree of crystallinity and transparency could be obtained without the continuous material testing by DSC; 3) image analysis is potentially applicable for assessment of other crystalline polymers.
International Journal of Biological Macromolecules, Jul 1, 2018
Present study reports synthesis and physico-chemical evaluation of hydrophobically modified pecti... more Present study reports synthesis and physico-chemical evaluation of hydrophobically modified pectin derivatives, obtained by reacting of pectin with di-acyl chlorides (glutaryl and sebacoyl chloride). Depending on length of the inserted carbon chains, the acylation resulted in possible formation of mono-grafted (isolated chains) and bi-grafted (chemical gels) structures. The structural features of obtained derivatives were investigated using FTIR spectroscopy, confirming the successful synthesis. The concentrated aqueous solutions of modified pectin showed interesting rheological properties, having lower values of apparent viscosity compared to neat pectin. Since the GPC analysis indicated that no degradation occurred, the viscosity decrease was explained by more heterogeneous organization within modified pectin solutions (microparticles together with sticky polymer entanglement). A shift in particle size distribution proved that proposed modifications also affected pectin solution properties in diluted regime. The modified samples turned to be more sensible to thermal degradation than neat pectin, whereby the increasing size of flexible acyl chains attached to a polymer backbone reduced the glass transition temperature. The hydrophobicity of obtained derivatives was evaluated by sessile drop and du Nouy ring methods. It was found that acylation enhanced hydrophobicity of the pectin molecule, while hydrophobically associative character turned to be inconsistent in aqueous and non-aqueous environment.
Journal of materials chemistry. A, Materials for energy and sustainability, 2016
Mimicking the excellence of natural materials presents an attractive route in the synthesis of ad... more Mimicking the excellence of natural materials presents an attractive route in the synthesis of advanced functional materials.
Environmental Science and Pollution Research, 2019
Nowadays, the extensive use of pesticides in crops production puts a significant challenge to min... more Nowadays, the extensive use of pesticides in crops production puts a significant challenge to minimize its side effects along with safe production, storage, and after-use treatment. This paper reports results related to the emission of certain pesticide formulations through the PET containers, as well as, their mitigation to the PET containers during their storage. The influence of storage time on cypermethrin migration to and through the PET was studied in short-term Collaborative International Pesticides Analytical Council test lasting up to 30 days. The PET containers were filled with pure xylene and pesticide formulations, where the amount of active substance, cypermethrin (CY), varied from 5 to 20 wt%, while the amount of emulsifier was kept constant. The results indicate that pesticide formulations diffuse to PET containers with an average increase of its initial mass up to 1.5%. The most intensive diffusion is in the first 24 months of storage, after its rate significantly decreases. It should be noted that the diffusion studied pesticide formulations are also very dependent on CY concentration. Besides the migration to the PET containers, it was also found that pesticide formulation was emitted through the PET containers in the first 17 to 24 months of storage depending on CY concentration. Emission rates were also dependent on CY concentration and were in the range of 15.3 to 38.0 mg/month•container. The emission through the PET containers was successfully predicted using artificial neural networks with R 2 = 0.94 and the mean absolute percentage error (MAPE) of only 6.2% on testing.
During the last two decades, interest in bio-based polymers, especially in bio-based composite ma... more During the last two decades, interest in bio-based polymers, especially in bio-based composite materials, has grown as a result of environmental concerns. In this paper new composites obtained from fully bio-based unsaturated polyester resin (UPR) and waste poly(ethylene terephthalate) (PET) were studied for the first time. The composites were prepared by crosslinking the UPR in the presence of functionalized PET particles (3, 6 and 9 wt %), using dimethyl itaconate as reactive diluent. The results showed that the incorporation of the PET particles led to the increase in mechanical properties. However, higher PET loading caused a decrease in the mechanical properties of the composites because of the PET particle agglomeration.
The design of complex polymeric materials with predefined task-specific properties meets challeng... more The design of complex polymeric materials with predefined task-specific properties meets challenging issues: to establish synthesis-structure-properties relationship, as well as to understand the arrangement and interactions of the involved components. Hybrid networks of protein (casein) and polyelectrolyte (poly(methacrylic acid)) were synthesized and their swelling, dynamic-mechanical and morphological properties were investigated as functions of the neutralization degree of methacrylic acid and the concentrations of caseinate and crosslinker. The domination of different interactions between components led to diverse forms of casein macromoleculesfrom micelles to unfold chains. That resulted in very different structures and thereby properties of derived hybrid networks: from porous unswellable to highly swellable and reinforced ones. A great opportunity to easily modulate the final characteristics of the reported hybrid system to fit the need of specific application just through the change of one synthesis parameter was thereby demonstrated.
Synthesis of high-performance anticorrosive coatings obtained from alkyd resins (ARs) based on wa... more Synthesis of high-performance anticorrosive coatings obtained from alkyd resins (ARs) based on waste poly(ethylene terephthalate) (PET) glycolyzates is presented. PET glycolyzates, synthesized by catalytic depolymerization with trimethylolpropane (TMP) and dipropylene glycol (DPG), were used as replacement of part of the polyhydroxylic component during the ARs synthesis. The obtained glycolyzates and ARs were analyzed using FT-IR and 1 HNMR spectroscopy and acid, iodine, and hydroxyl value were determined. Thickness, adhesion, swelling, corrosion, spraying and layering of the synthesized ARs, as well as alkyd coating film were determined in accordance with SRPS EN ISO standards. ARs were produced in high yields and FT-IR and 1 NMR analysis results confirmed assumed structures. All synthesized ARs show good elasticity, flexibility, adhesion and the gloss values are greater than 85 %, and the alkyd coating films based on AR1 and AR3 showed best corrosion results. The most effective dryer catalyst combination was 0.5 wt.% Ca, 0.03 wt.%, Co and 0.45 wt.% Zr.
Abstract Electricity generation using carbon-based fuels is responsible for a large fraction of c... more Abstract Electricity generation using carbon-based fuels is responsible for a large fraction of carbon dioxide emissions worldwide. In Serbia, 70% of the electricity is produced from coal-fired power plants. The aim of this investigation was to identify the retrofitting opportunities to reduce the carbon intensity of power generation. Resource Efficient and Cleaner Production assessment was performed in a coal thermal power plant of the public company “Thermal Power Plants Nikola Tesla”, which operates within the Electric Power Industry of Serbia. Assessment of the thermal power plant operation was supported by experimentally measured data (fresh water pressures and temperatures, steam temperatures and pressures, condensing pressure, water flowrate, make-up water flowrate, steam flowrate, coal composition, emissions, etc), emission factor determinations and by using data obtained during unit balancing and simulation of the system's performance. The data collected and analyzed during power plant operation were used for the development of a new general approach with comprehensive analysis of the system, using the following plant eco-efficiency indicators: energy consumption, climate change, acidification, and waste generation. Indicators were used to present decoupling after implementation of the described measures. The analysis of two units showed that the nominal power could be increased by 60 MWe, with an increase of the unit gross efficiency of 0.4%, and a reduction of coal, water and electricity consumption. The implementation of RECP measures in this study enabled analysis of the overall performance of the system as evidenced by the eco-efficiency indicators: energy consumption (decreased by 3%), CO2 emission (decreased by 3%), and SO2 emission (decreased by 39%). Consequently, it may be concluded that the proposed RECP approach, tested on thermal power plants, and presented as eco-efficiency indicators show that the described methodology may be successfully implemented in the energy sector and for the improvement in power plants.
Journal of Materials Science: Materials in Electronics, 2015
Abstract Polymers are very attractive as thin films in emerging reel-to-reel manufacturing or as ... more Abstract Polymers are very attractive as thin films in emerging reel-to-reel manufacturing or as spin coated from liquid form in a quick and low cost process in standard microfabrication processes. There is a wide selection of materials available with many different thermal, electrical, and mechanical properties. With continuous growth in consumer electronics and sensors sectors, the range of potential application fields is further diversifying and integration of MEMS modules, as well as delivering IC functionality in thin foil-like packaging with proven reliability and reduction in cost is increasingly required. Furthermore, increased volume and decentralisation of testing within medical diagnostics field worldwide (IVD Point of Care and Patient Self Testing trends) require low cost solutions for disposable test cartridges and other supporting consumables. In majority of the emerging medical applications, integrated, low cost sensors need to operate in liquid environment, often rendering the use of standard Si-based solutions inadequate and costly. Polymer-based microcantilevers, realised by standard surface microfabrication techniques, were chosen for this study as the alternative approach to Si-based MEMS. Cantilevers are well understood microstructures and so provide an excellent vehicle for assessing both thermo-mechanical properties of polymers as MEMS materials and their potential for die-level packaging and integration into miniaturized systems. Due to the nature of processes involved and their thermal budget, substitution of Si substrate with e.g. flexible substrates or polymer films is foreseen in the near future. Fabricated cantilever beams consist of various combinations of thin metal/polymer and polymer/polymer films. Polyimides, as structural material, have been selected for this study due to inherently good mechanical properties, good chemical resistance, low dielectric constant and high thermal stability.
A new perspective for mass production of alkyd resins from multifunctional glycolyzates obtained ... more A new perspective for mass production of alkyd resins from multifunctional glycolyzates obtained from waste PET – a step up to greener production and excellent applicative properties.
Non-isothermal thermogravimetry was performed in a dynamic nitrogen atmosphere, on a series of po... more Non-isothermal thermogravimetry was performed in a dynamic nitrogen atmosphere, on a series of poly(di-n-propyl itaconates) (PDnPI) and poly(di-iso-propyl itaconates) (PDiPI) which had been prepared in the presence of various amounts of the chain transfer agent n-dodecyl mercaptan (DDM). Differential thermogravimetry (DTG) showed that both polymers degraded in two stages. The DTG curve of PDnP1 had a large first peak followed by a smaller shoulder, whereas the DTG curve of PDiPI was composed of two peaks of almost equal heights. The addition of DDM during the polymerisations in both cases resulted in a similar decrease in the relative area of the first peak.
Itaconic acid, IA (C5H6O4), was investigated as a potential flocculant for the aqueous processing... more Itaconic acid, IA (C5H6O4), was investigated as a potential flocculant for the aqueous processing of alumina powders. The adsorption of IA, as a function of its concentration and pH value of the solution, onto the alumina surface was studied by the solution depletion method. The stability of the suspensions in the presence of itaconic acid was evaluated in light of the surface charge of the alumina powder used, the degree of dissociation of IA, as well as the sedimentation behavior and rheology of the suspensions. It was found that the adsorption process is extremely pH dependent; the maximum adsorption of IA onto alumina surface occurring at a pH close to the value of the first IA dissociation constant, pKa1. Also, IA does not influence the value of the point of zero charge of alumina. It was shown that IA represents an efficient flocculant for concentrated acidic alumina suspensions.
International Journal of Polymeric Materials, 2012
Biodegradable crosslinked biopolyesters and interpenetrating networks (IPN) were prepared with po... more Biodegradable crosslinked biopolyesters and interpenetrating networks (IPN) were prepared with poly(cardanol fumarate) (MCFR) and poly(castor oil fumarate) (CFR). Addition polymerization and crosslinking with styrene-free vinyl monomers, vinyl acetate (VA) and n-vinyl pyrrolidone (VP) was adopted to prepare these materials. The IPNs have higher thermal stability and mechanical properties in comparison with the crosslinked biopolyesters. The improved characteristics of IPNs are
Eight selected trace elements, which are generally included in regulations, were analyzed in 23 t... more Eight selected trace elements, which are generally included in regulations, were analyzed in 23 types of bottled waters. Ten mineral and seven spring bottled waters were from the Serbian market and six mineral bottled waters were obtained in different EU countries. For the purpose of comparison, selected tap waters were also analyzed. Inductively coupled plasma mass spectrometry (ICP-MS) was used for the analysis of trace elements (arsenic, cadmium, copper, manganese, nickel, lead and antimony). Results were compared with the Serbian regulations for bottled water, EU regulations and guideline values set by the World Health Organization for drinking water. With few exceptions, the trace element levels of most bottled waters were below the guideline values. However, a higher content of antimony was observed in waters from polyethylene terephthalate (PET) containers, indicating a potential leaching of this element from the plastic packaging.
The oxidative thermal degradation of poly(2-chloroethyl methacrylate) (PCEMA) was studied in the ... more The oxidative thermal degradation of poly(2-chloroethyl methacrylate) (PCEMA) was studied in the presence of the following commercial antioxidants: CHIMASSORB 119 (CH 119) and CHIMASSORB 944 (CH 944), both based on amines, and a mixture of IRGANOX 1010, a phenol derivative, and IRGAPHOS 168, a phosphite (mass ratio 1:1), by the thermogravimetric (TG) method. On the basis of the obtained results, the characteristic temperatures of 10% mass loss, Tio%, the shape of the differential TG (DTG) curves and mean values of the thermal degradation activation energy, Ea, it was concluded that the commercial photostabilisers CH 119 and CH 944 could not successfully stabilize the thermal degradation of PCEMA, while in the case of the presence of the antioxidant mixture IRGANOX 1010 and IRGAPHOS 168 (1:1) slight stabilizing effects were observed.
The non-oxidative thermal degradation of poly(iso-butyl methacrylate) and poly(sec-butyl methacry... more The non-oxidative thermal degradation of poly(iso-butyl methacrylate) and poly(sec-butyl methacrylate) was investigated by studying changes in the polymer residue. Due to the different number of β-hydrogens in their ester substituents, these two polymeric isomers behave differently when subjected to elevated temperatures. Poly(iso-butyl methacrylate) degrades quantitatively by depolymerisation with zip lengths of the same order of magnitude as those of poly(methyl methacrylate). Poly(sec-butyl methacrylate) degrades by a combined degradation mechanism of depolymerisation and de-esterification. De-esterification becomes a significant thermolysis route at temperatures higher than 240 ºC.
The aim of this paper is to present image analysis as a useful technique for fast, reliable and n... more The aim of this paper is to present image analysis as a useful technique for fast, reliable and non-destructive detection of dimensional and structural changes in polymers. The possibility of applying image analysis was demonstrated in the case of solvent-induced crystallization of poly(ethylene terephthalate) (PET) containers filled with commonly used organic solvents: chlorobenzene, isophorone, xylene, Espesol, Shellsol A 100, Solvesso 150, propylene glycol, glycerin and water and subjected to the storage stability test at 54 °C for 14 days (CIPAC 1-MT 46.1.3). In addition, the obtained results were analyzed using one-step analysis of variance (ANOVA) combined with the Duncan's statistical test (p<0.05). According to the achieved results, three main impacts of the presented paper could be distinguished: 1) dimensional and transparency changes could be precisely followed by image analysis in both following cases: for small changes in water, as well as for significant ones in chlorobenzene; 2) a correlation between the changes in the degree of crystallinity and transparency could be obtained without the continuous material testing by DSC; 3) image analysis is potentially applicable for assessment of other crystalline polymers.
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