Branka Mušič - Academia.edu (original) (raw)

Papers by Branka Mušič

Polymers

The growing awareness of the consequences of climate change has prompted the formulation of polic... more The growing awareness of the consequences of climate change has prompted the formulation of policies and regulations to foster sustainability [...]

Polymers

Bio-solids (biological sludge) from wastewater treatment plants are a significant source of the e... more Bio-solids (biological sludge) from wastewater treatment plants are a significant source of the emission of microplastics (MPs) into the environment. Weakening the structure of MPs before they enter the environment may accelerate their degradation and reduce the environmental exposure time. Therefore, we studied the effect of UV-A and UV-C, applied at 70 °C, on three types of MPs, polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET), that are commonly found in sewage sludge, using three shapes (fibers, lines, granules). The MPs were exposed to UV radiation in bio-solid suspensions, and to air and water as control. The structural changes in and degradation of the MPs were investigated using Attenuated Total Reflectance–Fourier Transform Infrared Spectrometry (ATR-FTIR) and surface morphology was performed with SEM analysis. UV exposure led to the emergence of carbonyl and hydroxyl groups in all of the PP samples. In PE and PET, these groups were formed only in ...

Polymers

Cellulose acetate is used in many applications, including for cigarette filters. Unfortunately, u... more Cellulose acetate is used in many applications, including for cigarette filters. Unfortunately, unlike cellulose, its (bio)degradability is under question, yet it often ends up uncontrolled in the natural environment. The main purpose of this study is to compare the effects of weathering on two types of cigarette filter (classic filters and newer filters that have more recently arrived on the market) following their use and disposal in nature. Microplastics were prepared from polymer parts of used (classic and heated tobacco products—HTP) cigarettes and artificially aged. TG/DTA, FTIR, and SEM analyses were performed both before and after the aging process. Newer tobacco products contain an additional film made of a poly(lactic acid) polymer which, like cellulose acetate, burdens the environment and poses a risk to the ecosystem. Numerous studies have been conducted on the disposal and recycling of cigarette butts and cigarette butt extracts, revealing alarming data that have also i...

Molecular therapy. Nucleic acids, Jan 28, 2014

The melanoma cell adhesion molecule (MCAM) is involved in melanoma development and its progressio... more The melanoma cell adhesion molecule (MCAM) is involved in melanoma development and its progression, including invasiveness, metastatic potential and angiogenesis. Therefore, MCAM represents a potential target for gene therapy of melanoma, whose expression could be hindered with posttranscriptional specific gene silencing with RNA interference technology. In this study, we constructed a plasmid DNA encoding short hairpin RNA against MCAM (pMCAM) to explore the antitumor and antiangiogenic effects. The experiments were performed in vitro on murine melanoma and endothelial cells, as well as in vivo on melanoma tumors in mice. The antiproliferative, antimigratory, antiangiogenic and antitumor effects were examined after gene therapy with pMCAM. Gene delivery was performed by magnetofection, and its efficacy compared to gene electrotransfer. Gene therapy with pMCAM has proved to be an effective approach in reducing the proliferation and migration of melanoma cells, as well as having anti...

BioMed Research International, 2013

Magnetofection is a nanoparticle-mediated approach for transfection of cells, tissues, and tumors... more Magnetofection is a nanoparticle-mediated approach for transfection of cells, tissues, and tumors. Specific interest is in using superparamagnetic iron oxide nanoparticles (SPIONs) as delivery system of therapeutic genes. Magnetofection has already been described in some proof-of-principle studies; however, fine tuning of the synthesis of SPIONs is necessary for its broader application. Physicochemical properties of SPIONs, synthesized by the co-precipitation in an alkaline aqueous medium, were tested after varying different parameters of the synthesis procedure. The storage time of iron(II) sulfate salt, the type of purified water, and the synthesis temperature did not affect physicochemical properties of SPIONs. Also, varying the parameters of the synthesis procedure did not influence magnetofection efficacy. However, for the pronounced gene expression encoded by plasmid DNA it was crucial to functionalize poly(acrylic) acid-stabilized SPIONs (SPIONs-PAA) with polyethyleneimine (P...

Global Journal of Ecology

This review brings together data on the impact of (micro)plastics, on the environment. Critically... more This review brings together data on the impact of (micro)plastics, on the environment. Critically evaluates studies on the use of various techniques for recycling textile plastic, which is a major polluter of the environment. In this review, let’s focus a bit more on industrial waste in the textile industry since it would be easiest possible to capture and recycle it again. We also discuss LCA studies, bottlenecks, and future perspectives, for a lower impact on the environment. The main challenges which make further recycling progress difficult are discussed, such as the lamination of textile fibers with metal, new textile fibers that appear as a result of rapid development, the difference in the density of textile fibers, low recycling efficiency, etc. Finally, the possible uses of more environmentally friendly polymers are shown, which can be an alternative to the current synthetic polymers. The results of the literature review showed that for the development of a sustainable text...

5th International Conference on Technologies & Business Models for Circular Economy: Conference Proceedings

The building and civil engineering industry generates more than 40% of man-caused carbon emission... more The building and civil engineering industry generates more than 40% of man-caused carbon emissions, consumes a lot of energy just to produce building materials, generates a large amount of waste through construction and demolition, and consumes a large amount of natural resources. One of the possible solutions is to use alkali-activated materials, which can use waste instead of raw materials and are produced at lower temperatures, with less energy consumption and in less time than traditional building products. All of this lowers the carbon footprint, which could be further reduced by the timely-short implementation of microwave irradiation in the early stages of alkali-activation synthesis. Therefore, metakaolin activated with Na-water glass in a theoretically optimal ratio was irradiated with microwaves of 2.45 GHz at powers of 100 W and 1000 W for 1 min, and compared to non-irradiated reference cured only at room conditions. Samples prepared at higher power, i.e., 1000 W, solidif...

Polymers

Magnetic extraction offers a rapid and low-cost solution to microplastic (MP) separation, in whic... more Magnetic extraction offers a rapid and low-cost solution to microplastic (MP) separation, in which we magnetize the hydrophobic surface of MPs to separate them from complex environmental matrices using magnets. We synthesized a hydrophobic Fe-silane based nanocomposite (Fe@SiO2/MDOS) to separate MPs from freshwater. Pristine and weathered, polyethylene (PE) and tire wear particles (TWP) of different sizes were used in the study. The weathering of MPs was performed in an accelerated weathering chamber according to ISO 4892-2:2013 standards that mimic natural weathering conditions. The chemical properties and morphology of the Fe@SiO2/MDOS, PE and TWP were confirmed by Fourier transform infrared spectroscopy and Scanning electron microscopy, respectively. The thermal properties of PE and TWP were evaluated by Thermogravimetric analysis. Using 1.00 mg of Fe@SiO2/MDOS nanocomposite, 2.00 mg of pristine and weathered PE were extracted from freshwater; whereas, using the same amount of th...

Zenodo (CERN European Organization for Nuclear Research), Nov 17, 2022

Cigarette filters (butts) are one of the most abundant form of anthropogenic litter. Once dispose... more Cigarette filters (butts) are one of the most abundant form of anthropogenic litter. Once disposed into the environment, they are subjected to weathering, such as UV radiation and other. During this process nano-and microplastics are formed. The aim of this study was to investigate the effects of cellulose acetate-based microplastics, produced by grinding nonused cigarette filters, on freshwater crustacean Daphnia magna, mealworm larvae Tenebrio molitor, and terrestrial crustacean Porcellio scaber. In addition, microplastics from cigarette filter was also aged under UV irradiation, according to the standard ISO 4892-2:2013, which specifies test conditions for replicating the weathering effects on plastic materials by xenon arc light in an accelerated weathering chamber. Therefore, a comparison study of the effects of aged and unaged microplastics on D. magna was also an important aim of this work. A comprehensive characterization of the prepared microplastic was performed by TG/DTA, FTIR analysis and scanning electron microscopy, which revealed irregularly shaped particles (< 250 um). The results showed that a 7-day exposure to microplastics from cigarette filters at concentrations of 0.06% and 0.5% w/w per dry soil slightly altered the immune processes of P. scaber, as evidenced by a decreased total haemocyte count. In contrast, a 14day exposure caused no changes in the measured immune parameters in the haemolymph. In mealworm larvae, energy related traits, e.g. electron transport system (ETS) activity and lipid content, were measured. We observed an enhanced ETS activity at 0.5% w/w and increased lipid content after 14 days of exposure to 0.5% and 1.5% w/w. On contrary, no effects of exposure to unaged and UV-aged microplastics on D. magna were observed. Overall, research findings suggest that cellulose acetate-based microplastics from cigarette filters may induce an altered physiological profile in terrestrial invertebrates, but no severe adverse effects were observed under conditions tested.

Polymers

Hybrid phenol-formaldehyde (PF) resins represent one of the most important niche groups of bindin... more Hybrid phenol-formaldehyde (PF) resins represent one of the most important niche groups of binding systems for composites. New industrial needs, environmental requirements, and price fluctuations have led to further research on materials with enhanced mechanical and thermal properties. The preparation of novel hybrid materials can be achieved by inclusion of various elements or functional groups in the organic polymer phenolic framework. Herein, we report the synthesis and characterization of a PF-based hybrid material with different nanoscale silicone species and ZnAl-layered double hydroxide (LDH). The main goals of this study were to improve the synthetic pathways of hybrid resin, as well as to prepare granulated composite materials and test samples and determine their characterization. Added inorganic species increased the glass-transition temperature by a minimum of 8 °C, which was determined using differential scanning calorimetry (DSC). Rheological properties (melting viscosi...

Polymers

In the presented work, the influence of two flame retardants—ammonium polyphosphates and 2,4,6-tr... more In the presented work, the influence of two flame retardants—ammonium polyphosphates and 2,4,6-triamino-1,3,5-triazine on the polyurethane foam (PUR) systems were studied. In this paper, these interactive properties are studied by using the thermal analytical techniques, TGA and DTA, which enable the various thermal transitions and associated volatilization to be studied and enable the connection of the results with thermal and mechanical analysis, as are thermal conductivities, compression and bending behavior, hardness, flammability, and surface morphology. In this way, a greater understanding of what the addition of fire retardants to polyurethane foams means for system flammability itself and, on the other hand, how this addition affects the mechanical properties of PUR may be investigated. It was obtained that retardants significantly increase the fire resistance of the PURs systems while they do not affect the thermal conductivity and only slightly decrease the mechanical prop...

Microplastics and Nanoplastics

The COVID-19 pandemic has increased the use of disposable plastics, including medical masks, whic... more The COVID-19 pandemic has increased the use of disposable plastics, including medical masks, which have become a necessity in our daily lives. As these are often improperly disposed of, they represent an important potential source of microplastics in the environment. We prepared microplastics from polypropylene medical masks and characterised their size, shape, organic chemical leaching, and acute toxicity to the planktonic crustacean Daphnia magna. The three layers of the masks were separately milled and characterised. Each of the inner frontal, middle filtering, and outer layers yielded different types of microplastics: fibres were obtained from the inner and outer layer, but irregular fragments from the middle layer. The shape of the obtained microplastics differed from the initial fibrous structure of the intact medical mask layers, which indicates that the material is deformed during cryo-milling. The chemical compositions of plastics-associated chemicals also varied between th...

Cellulose, 2021

Differently structured aluminum (tri/mono) hydroxide (Al(OH)3 /AlO(OH)) nanoparticles were prepar... more Differently structured aluminum (tri/mono) hydroxide (Al(OH)3 /AlO(OH)) nanoparticles were prepared and used as thermal-management additives to microfibrillated cellulose (MFC), cast-dried in thin-layer films. Both particles increased the thermal stability of the MFC film, yielding 20–23% residue at 600 °C, and up to 57% lowered enthalpy (to 5.5–7.5 kJ/g) at 0.15 wt% of loading, while transforming to alumina (Al2O3). However, the film containing 40 nm large Al(OH)3 particles decomposed in a one-step process, and released up to 20% more energy between 300 and 400 °C as compared to the films prepared from smaller (21 nm) and meta-stable AlO(OH), which decomposed gradually with an exothermic peak shifted to 480 °C. The latter resulted in a highly flexible, optically transparent (95%), and mechanically stronger (5.7 GPa) film with a much lower specific heat capacity (0.31–0.28 J/gK compared to 0.68–0.89 J/gK for MFC-Al(OH)3 and 0.87–1.26 for MFC films), which rendered it as an effective...

Nanocelluloses have been studied as high technology biopolymers for application in various materi... more Nanocelluloses have been studied as high technology biopolymers for application in various materials, including the development of films or coatings and reinforcement of a paper (Lengowski, 2019). The thermal stability of nanocellulose based materials is also been of a great concern, generating new and forthcoming applications in digitalized materials and electronics (Agate, 2018; Abitbol, 2016). Although the heat resistance properties of fibrous/polymeric products can be generally improved by different Fire Retardants (FRs), most of them are oil-derived organic compounds (e.g. organo-halogenated, organo-phosphorous, organo-nitrogen compounds)

Materials, 2020

Global industries strive towards the production of materials with superior mechanical characteris... more Global industries strive towards the production of materials with superior mechanical characteristics, and their development remains a big challenges. One of the more interesting materials that exhibit these properties are silicate-filled epoxy molding compounds (EMCs). A good interaction between silicate filler and epoxy matrix is generally needed to achieve advantageous mechanical properties, as well as the desirable rheological behavior of EMCs. Understanding the influence of different organosilane coupling agents on the rheological and mechanical properties of EMCs is essential in the development and optimization of the manufacturing process. For this matter, a mixture of calcium silicate and aluminosilicate was treated by using organosilane coupling agents with different chemical structures and thus treated silicates were applied as fillers in the EMCs. The thermal behavior of the organosilane-modified, silicate-filled EMCs was studied by using differential scanning calorimetry...

Around 15 years have passed since the wireless technologies started with rapid development. Durin... more Around 15 years have passed since the wireless technologies started with rapid development. During that time, different fields of electromagnetic waves have become more active. As a result of rapid advances in technology the use of wireless communication and radar systems is expanding quickly, which leads to a significant increase in the levels of background electromagnetic (EM) radiation /1/. To avoid potential health effects from high exposure to electromagnetic waves, unnecessary EM waves should be eliminated to protect human bodies, especially expectant mothers and children /2/. In European Pre-standard ENV 50166-2:1995 – Human exposure to electromagnetic fields – High frequency, is stated that electromagnetic fields interact with the human body and other systems through a number of physical mechanisms. Therefore, it is necessary to protect all of these systems. As mentioned in ENV standard, it is recognized that additional considerations have been made by some countries, regard...

Differently structured aluminum (tri/mono) hydroxide (Al(OH)3 / AlO(OH)) nanoparticles were prepa... more Differently structured aluminum (tri/mono) hydroxide (Al(OH)3 / AlO(OH)) nanoparticles were prepared and used as thermal-management additives to microfibrillated cellulose (MFC), cast-dried in thin-layer films. Both particles increased the thermal stability of the MFC film, yielding 20–23% residue at 600 °C, and up to 57% lowered enthalpy (to 5.5–7.5 kJ/g) at 0.15 wt% of loading, while transforming to Al2O3. However, the film containing 40 nm large Al(OH)3 particles decomposed in a one-step process, and released up to 20 % more energy between 300–400°C as compared to the films prepared from smaller (21 nm) and meta-stable AlO(OH), which decomposed gradually with an exothermic peak shifted to 480 °C. The latter resulted in a highly flexible, optically transparent (95%), and mechanically stronger (5.7 GPa) film with a much lower specific heat capacity (0.31 − 0.28 J/gK compared to 0.68–0.89 J/gK for MFC-Al(OH)3 and 0.87–1.26 for MFC films), which render it as an effective heat-dissipa...

Mnogi sodobni materiali s svojimi izboljsanimi ali povsem novimi lastnostmi resujejo stevilne pro... more Mnogi sodobni materiali s svojimi izboljsanimi ali povsem novimi lastnostmi resujejo stevilne probleme in s tem ponujajo dodano vrednost pri uporabi. Razsirili so se napredni kompozitni materiali, saj je njihova velika prednost, da lahko njihove lastnosti nacrtujemo vnaprej glede na njihovo koncno uporabo. Umetno povzrocena elektromagnetna sevanja (EMS) povecujejo negativen vpliv EMS na žive organizme. Zato so stevilne evropske države že pred casom odlocile, da scitijo svoje državljane z nacionalnimi ukrepi (Evropskem Pre-standardu EN 50166-2 – Human exposure to electromagnetic fields – High frequency). Žive organizme, naprave in prostore lahko zascitimo pred elektromagnetnim sevanjem tako, da ga odbijemo ali absorbiramo. Pri odbojni zasciti se lahko uporabi tanka plast odbojnega materiala ali barve. Ti materiali so v svetu že znani in razsirjeni. Kot posledica odbojne zascite pa se lahko bistveno poveca stevilo motenj v okolici. Pri absorpcijski zasciti se odbije le manjsi delež up...

Catalysis Reviews, 2019

The present review compiles and critically evaluates studies on the synthesis of dimethyl carbona... more The present review compiles and critically evaluates studies on the synthesis of dimethyl carbonate (DMC) using different techniques and catalysts with reaction conditions, a wide range of applications and environmental impact. In this review, we compare different strategies, wide variety of catalysts, and advantages and disadvantages of various DMC synthesis routes. We particularly focus on catalyst advancements for DMC synthesis from transesterification of carbonates/urea, and direct or indirect conversions of CO 2. Mechanisms of synthesis along with future perspectives have also been discussed. The transesterification of propylene carbonate and ethylene carbonate is an effective process for DMC synthesis. CO 2 with methanol is an emerging route for DMC synthesis. The major problems in various routes such as thermodynamic limitations, low yield and reaction rate, deactivation of catalyst due to hydrolysis have been discussed. Finally, potential applications of DMC and effective use as a multifunctional compound are exemplified.

Materials, 2019

Global design and manufacturing of the materials with superb properties remain one of the greates... more Global design and manufacturing of the materials with superb properties remain one of the greatest challenges on the market. The future progress is orientated towards researches into the material development for the production of composites of better mechanical properties to the existing materials. In the field of advanced composites, epoxy molding compounds (EMCs) have attained dominance among the common materials due to their excellent properties that can be altered by adding different fillers. One of the main fillers is often based on silicon dioxide (SiO2). The concept of this study was to evaluate the effects of the selected silica-based fillers on the thermal, rheological, and mechanical properties of EMCs. Various types of fillers with SiO2, including crystalline silica and fused silica, were experimentally studied to clarify the impact of filler on final product. Fillers with different shape (scanning electron microscope, SEM), along with different specific surface area (spe...

Polymers

The growing awareness of the consequences of climate change has prompted the formulation of polic... more The growing awareness of the consequences of climate change has prompted the formulation of policies and regulations to foster sustainability [...]

Polymers

Bio-solids (biological sludge) from wastewater treatment plants are a significant source of the e... more Bio-solids (biological sludge) from wastewater treatment plants are a significant source of the emission of microplastics (MPs) into the environment. Weakening the structure of MPs before they enter the environment may accelerate their degradation and reduce the environmental exposure time. Therefore, we studied the effect of UV-A and UV-C, applied at 70 °C, on three types of MPs, polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET), that are commonly found in sewage sludge, using three shapes (fibers, lines, granules). The MPs were exposed to UV radiation in bio-solid suspensions, and to air and water as control. The structural changes in and degradation of the MPs were investigated using Attenuated Total Reflectance–Fourier Transform Infrared Spectrometry (ATR-FTIR) and surface morphology was performed with SEM analysis. UV exposure led to the emergence of carbonyl and hydroxyl groups in all of the PP samples. In PE and PET, these groups were formed only in ...

Polymers

Cellulose acetate is used in many applications, including for cigarette filters. Unfortunately, u... more Cellulose acetate is used in many applications, including for cigarette filters. Unfortunately, unlike cellulose, its (bio)degradability is under question, yet it often ends up uncontrolled in the natural environment. The main purpose of this study is to compare the effects of weathering on two types of cigarette filter (classic filters and newer filters that have more recently arrived on the market) following their use and disposal in nature. Microplastics were prepared from polymer parts of used (classic and heated tobacco products—HTP) cigarettes and artificially aged. TG/DTA, FTIR, and SEM analyses were performed both before and after the aging process. Newer tobacco products contain an additional film made of a poly(lactic acid) polymer which, like cellulose acetate, burdens the environment and poses a risk to the ecosystem. Numerous studies have been conducted on the disposal and recycling of cigarette butts and cigarette butt extracts, revealing alarming data that have also i...

Molecular therapy. Nucleic acids, Jan 28, 2014

The melanoma cell adhesion molecule (MCAM) is involved in melanoma development and its progressio... more The melanoma cell adhesion molecule (MCAM) is involved in melanoma development and its progression, including invasiveness, metastatic potential and angiogenesis. Therefore, MCAM represents a potential target for gene therapy of melanoma, whose expression could be hindered with posttranscriptional specific gene silencing with RNA interference technology. In this study, we constructed a plasmid DNA encoding short hairpin RNA against MCAM (pMCAM) to explore the antitumor and antiangiogenic effects. The experiments were performed in vitro on murine melanoma and endothelial cells, as well as in vivo on melanoma tumors in mice. The antiproliferative, antimigratory, antiangiogenic and antitumor effects were examined after gene therapy with pMCAM. Gene delivery was performed by magnetofection, and its efficacy compared to gene electrotransfer. Gene therapy with pMCAM has proved to be an effective approach in reducing the proliferation and migration of melanoma cells, as well as having anti...

BioMed Research International, 2013

Magnetofection is a nanoparticle-mediated approach for transfection of cells, tissues, and tumors... more Magnetofection is a nanoparticle-mediated approach for transfection of cells, tissues, and tumors. Specific interest is in using superparamagnetic iron oxide nanoparticles (SPIONs) as delivery system of therapeutic genes. Magnetofection has already been described in some proof-of-principle studies; however, fine tuning of the synthesis of SPIONs is necessary for its broader application. Physicochemical properties of SPIONs, synthesized by the co-precipitation in an alkaline aqueous medium, were tested after varying different parameters of the synthesis procedure. The storage time of iron(II) sulfate salt, the type of purified water, and the synthesis temperature did not affect physicochemical properties of SPIONs. Also, varying the parameters of the synthesis procedure did not influence magnetofection efficacy. However, for the pronounced gene expression encoded by plasmid DNA it was crucial to functionalize poly(acrylic) acid-stabilized SPIONs (SPIONs-PAA) with polyethyleneimine (P...

Global Journal of Ecology

This review brings together data on the impact of (micro)plastics, on the environment. Critically... more This review brings together data on the impact of (micro)plastics, on the environment. Critically evaluates studies on the use of various techniques for recycling textile plastic, which is a major polluter of the environment. In this review, let’s focus a bit more on industrial waste in the textile industry since it would be easiest possible to capture and recycle it again. We also discuss LCA studies, bottlenecks, and future perspectives, for a lower impact on the environment. The main challenges which make further recycling progress difficult are discussed, such as the lamination of textile fibers with metal, new textile fibers that appear as a result of rapid development, the difference in the density of textile fibers, low recycling efficiency, etc. Finally, the possible uses of more environmentally friendly polymers are shown, which can be an alternative to the current synthetic polymers. The results of the literature review showed that for the development of a sustainable text...

5th International Conference on Technologies & Business Models for Circular Economy: Conference Proceedings

The building and civil engineering industry generates more than 40% of man-caused carbon emission... more The building and civil engineering industry generates more than 40% of man-caused carbon emissions, consumes a lot of energy just to produce building materials, generates a large amount of waste through construction and demolition, and consumes a large amount of natural resources. One of the possible solutions is to use alkali-activated materials, which can use waste instead of raw materials and are produced at lower temperatures, with less energy consumption and in less time than traditional building products. All of this lowers the carbon footprint, which could be further reduced by the timely-short implementation of microwave irradiation in the early stages of alkali-activation synthesis. Therefore, metakaolin activated with Na-water glass in a theoretically optimal ratio was irradiated with microwaves of 2.45 GHz at powers of 100 W and 1000 W for 1 min, and compared to non-irradiated reference cured only at room conditions. Samples prepared at higher power, i.e., 1000 W, solidif...

Polymers

Magnetic extraction offers a rapid and low-cost solution to microplastic (MP) separation, in whic... more Magnetic extraction offers a rapid and low-cost solution to microplastic (MP) separation, in which we magnetize the hydrophobic surface of MPs to separate them from complex environmental matrices using magnets. We synthesized a hydrophobic Fe-silane based nanocomposite (Fe@SiO2/MDOS) to separate MPs from freshwater. Pristine and weathered, polyethylene (PE) and tire wear particles (TWP) of different sizes were used in the study. The weathering of MPs was performed in an accelerated weathering chamber according to ISO 4892-2:2013 standards that mimic natural weathering conditions. The chemical properties and morphology of the Fe@SiO2/MDOS, PE and TWP were confirmed by Fourier transform infrared spectroscopy and Scanning electron microscopy, respectively. The thermal properties of PE and TWP were evaluated by Thermogravimetric analysis. Using 1.00 mg of Fe@SiO2/MDOS nanocomposite, 2.00 mg of pristine and weathered PE were extracted from freshwater; whereas, using the same amount of th...

Zenodo (CERN European Organization for Nuclear Research), Nov 17, 2022

Cigarette filters (butts) are one of the most abundant form of anthropogenic litter. Once dispose... more Cigarette filters (butts) are one of the most abundant form of anthropogenic litter. Once disposed into the environment, they are subjected to weathering, such as UV radiation and other. During this process nano-and microplastics are formed. The aim of this study was to investigate the effects of cellulose acetate-based microplastics, produced by grinding nonused cigarette filters, on freshwater crustacean Daphnia magna, mealworm larvae Tenebrio molitor, and terrestrial crustacean Porcellio scaber. In addition, microplastics from cigarette filter was also aged under UV irradiation, according to the standard ISO 4892-2:2013, which specifies test conditions for replicating the weathering effects on plastic materials by xenon arc light in an accelerated weathering chamber. Therefore, a comparison study of the effects of aged and unaged microplastics on D. magna was also an important aim of this work. A comprehensive characterization of the prepared microplastic was performed by TG/DTA, FTIR analysis and scanning electron microscopy, which revealed irregularly shaped particles (< 250 um). The results showed that a 7-day exposure to microplastics from cigarette filters at concentrations of 0.06% and 0.5% w/w per dry soil slightly altered the immune processes of P. scaber, as evidenced by a decreased total haemocyte count. In contrast, a 14day exposure caused no changes in the measured immune parameters in the haemolymph. In mealworm larvae, energy related traits, e.g. electron transport system (ETS) activity and lipid content, were measured. We observed an enhanced ETS activity at 0.5% w/w and increased lipid content after 14 days of exposure to 0.5% and 1.5% w/w. On contrary, no effects of exposure to unaged and UV-aged microplastics on D. magna were observed. Overall, research findings suggest that cellulose acetate-based microplastics from cigarette filters may induce an altered physiological profile in terrestrial invertebrates, but no severe adverse effects were observed under conditions tested.

Polymers

Hybrid phenol-formaldehyde (PF) resins represent one of the most important niche groups of bindin... more Hybrid phenol-formaldehyde (PF) resins represent one of the most important niche groups of binding systems for composites. New industrial needs, environmental requirements, and price fluctuations have led to further research on materials with enhanced mechanical and thermal properties. The preparation of novel hybrid materials can be achieved by inclusion of various elements or functional groups in the organic polymer phenolic framework. Herein, we report the synthesis and characterization of a PF-based hybrid material with different nanoscale silicone species and ZnAl-layered double hydroxide (LDH). The main goals of this study were to improve the synthetic pathways of hybrid resin, as well as to prepare granulated composite materials and test samples and determine their characterization. Added inorganic species increased the glass-transition temperature by a minimum of 8 °C, which was determined using differential scanning calorimetry (DSC). Rheological properties (melting viscosi...

Polymers

In the presented work, the influence of two flame retardants—ammonium polyphosphates and 2,4,6-tr... more In the presented work, the influence of two flame retardants—ammonium polyphosphates and 2,4,6-triamino-1,3,5-triazine on the polyurethane foam (PUR) systems were studied. In this paper, these interactive properties are studied by using the thermal analytical techniques, TGA and DTA, which enable the various thermal transitions and associated volatilization to be studied and enable the connection of the results with thermal and mechanical analysis, as are thermal conductivities, compression and bending behavior, hardness, flammability, and surface morphology. In this way, a greater understanding of what the addition of fire retardants to polyurethane foams means for system flammability itself and, on the other hand, how this addition affects the mechanical properties of PUR may be investigated. It was obtained that retardants significantly increase the fire resistance of the PURs systems while they do not affect the thermal conductivity and only slightly decrease the mechanical prop...

Microplastics and Nanoplastics

The COVID-19 pandemic has increased the use of disposable plastics, including medical masks, whic... more The COVID-19 pandemic has increased the use of disposable plastics, including medical masks, which have become a necessity in our daily lives. As these are often improperly disposed of, they represent an important potential source of microplastics in the environment. We prepared microplastics from polypropylene medical masks and characterised their size, shape, organic chemical leaching, and acute toxicity to the planktonic crustacean Daphnia magna. The three layers of the masks were separately milled and characterised. Each of the inner frontal, middle filtering, and outer layers yielded different types of microplastics: fibres were obtained from the inner and outer layer, but irregular fragments from the middle layer. The shape of the obtained microplastics differed from the initial fibrous structure of the intact medical mask layers, which indicates that the material is deformed during cryo-milling. The chemical compositions of plastics-associated chemicals also varied between th...

Cellulose, 2021

Differently structured aluminum (tri/mono) hydroxide (Al(OH)3 /AlO(OH)) nanoparticles were prepar... more Differently structured aluminum (tri/mono) hydroxide (Al(OH)3 /AlO(OH)) nanoparticles were prepared and used as thermal-management additives to microfibrillated cellulose (MFC), cast-dried in thin-layer films. Both particles increased the thermal stability of the MFC film, yielding 20–23% residue at 600 °C, and up to 57% lowered enthalpy (to 5.5–7.5 kJ/g) at 0.15 wt% of loading, while transforming to alumina (Al2O3). However, the film containing 40 nm large Al(OH)3 particles decomposed in a one-step process, and released up to 20% more energy between 300 and 400 °C as compared to the films prepared from smaller (21 nm) and meta-stable AlO(OH), which decomposed gradually with an exothermic peak shifted to 480 °C. The latter resulted in a highly flexible, optically transparent (95%), and mechanically stronger (5.7 GPa) film with a much lower specific heat capacity (0.31–0.28 J/gK compared to 0.68–0.89 J/gK for MFC-Al(OH)3 and 0.87–1.26 for MFC films), which rendered it as an effective...

Nanocelluloses have been studied as high technology biopolymers for application in various materi... more Nanocelluloses have been studied as high technology biopolymers for application in various materials, including the development of films or coatings and reinforcement of a paper (Lengowski, 2019). The thermal stability of nanocellulose based materials is also been of a great concern, generating new and forthcoming applications in digitalized materials and electronics (Agate, 2018; Abitbol, 2016). Although the heat resistance properties of fibrous/polymeric products can be generally improved by different Fire Retardants (FRs), most of them are oil-derived organic compounds (e.g. organo-halogenated, organo-phosphorous, organo-nitrogen compounds)

Materials, 2020

Global industries strive towards the production of materials with superior mechanical characteris... more Global industries strive towards the production of materials with superior mechanical characteristics, and their development remains a big challenges. One of the more interesting materials that exhibit these properties are silicate-filled epoxy molding compounds (EMCs). A good interaction between silicate filler and epoxy matrix is generally needed to achieve advantageous mechanical properties, as well as the desirable rheological behavior of EMCs. Understanding the influence of different organosilane coupling agents on the rheological and mechanical properties of EMCs is essential in the development and optimization of the manufacturing process. For this matter, a mixture of calcium silicate and aluminosilicate was treated by using organosilane coupling agents with different chemical structures and thus treated silicates were applied as fillers in the EMCs. The thermal behavior of the organosilane-modified, silicate-filled EMCs was studied by using differential scanning calorimetry...

Around 15 years have passed since the wireless technologies started with rapid development. Durin... more Around 15 years have passed since the wireless technologies started with rapid development. During that time, different fields of electromagnetic waves have become more active. As a result of rapid advances in technology the use of wireless communication and radar systems is expanding quickly, which leads to a significant increase in the levels of background electromagnetic (EM) radiation /1/. To avoid potential health effects from high exposure to electromagnetic waves, unnecessary EM waves should be eliminated to protect human bodies, especially expectant mothers and children /2/. In European Pre-standard ENV 50166-2:1995 – Human exposure to electromagnetic fields – High frequency, is stated that electromagnetic fields interact with the human body and other systems through a number of physical mechanisms. Therefore, it is necessary to protect all of these systems. As mentioned in ENV standard, it is recognized that additional considerations have been made by some countries, regard...

Differently structured aluminum (tri/mono) hydroxide (Al(OH)3 / AlO(OH)) nanoparticles were prepa... more Differently structured aluminum (tri/mono) hydroxide (Al(OH)3 / AlO(OH)) nanoparticles were prepared and used as thermal-management additives to microfibrillated cellulose (MFC), cast-dried in thin-layer films. Both particles increased the thermal stability of the MFC film, yielding 20–23% residue at 600 °C, and up to 57% lowered enthalpy (to 5.5–7.5 kJ/g) at 0.15 wt% of loading, while transforming to Al2O3. However, the film containing 40 nm large Al(OH)3 particles decomposed in a one-step process, and released up to 20 % more energy between 300–400°C as compared to the films prepared from smaller (21 nm) and meta-stable AlO(OH), which decomposed gradually with an exothermic peak shifted to 480 °C. The latter resulted in a highly flexible, optically transparent (95%), and mechanically stronger (5.7 GPa) film with a much lower specific heat capacity (0.31 − 0.28 J/gK compared to 0.68–0.89 J/gK for MFC-Al(OH)3 and 0.87–1.26 for MFC films), which render it as an effective heat-dissipa...

Mnogi sodobni materiali s svojimi izboljsanimi ali povsem novimi lastnostmi resujejo stevilne pro... more Mnogi sodobni materiali s svojimi izboljsanimi ali povsem novimi lastnostmi resujejo stevilne probleme in s tem ponujajo dodano vrednost pri uporabi. Razsirili so se napredni kompozitni materiali, saj je njihova velika prednost, da lahko njihove lastnosti nacrtujemo vnaprej glede na njihovo koncno uporabo. Umetno povzrocena elektromagnetna sevanja (EMS) povecujejo negativen vpliv EMS na žive organizme. Zato so stevilne evropske države že pred casom odlocile, da scitijo svoje državljane z nacionalnimi ukrepi (Evropskem Pre-standardu EN 50166-2 – Human exposure to electromagnetic fields – High frequency). Žive organizme, naprave in prostore lahko zascitimo pred elektromagnetnim sevanjem tako, da ga odbijemo ali absorbiramo. Pri odbojni zasciti se lahko uporabi tanka plast odbojnega materiala ali barve. Ti materiali so v svetu že znani in razsirjeni. Kot posledica odbojne zascite pa se lahko bistveno poveca stevilo motenj v okolici. Pri absorpcijski zasciti se odbije le manjsi delež up...

Catalysis Reviews, 2019

The present review compiles and critically evaluates studies on the synthesis of dimethyl carbona... more The present review compiles and critically evaluates studies on the synthesis of dimethyl carbonate (DMC) using different techniques and catalysts with reaction conditions, a wide range of applications and environmental impact. In this review, we compare different strategies, wide variety of catalysts, and advantages and disadvantages of various DMC synthesis routes. We particularly focus on catalyst advancements for DMC synthesis from transesterification of carbonates/urea, and direct or indirect conversions of CO 2. Mechanisms of synthesis along with future perspectives have also been discussed. The transesterification of propylene carbonate and ethylene carbonate is an effective process for DMC synthesis. CO 2 with methanol is an emerging route for DMC synthesis. The major problems in various routes such as thermodynamic limitations, low yield and reaction rate, deactivation of catalyst due to hydrolysis have been discussed. Finally, potential applications of DMC and effective use as a multifunctional compound are exemplified.

Materials, 2019

Global design and manufacturing of the materials with superb properties remain one of the greates... more Global design and manufacturing of the materials with superb properties remain one of the greatest challenges on the market. The future progress is orientated towards researches into the material development for the production of composites of better mechanical properties to the existing materials. In the field of advanced composites, epoxy molding compounds (EMCs) have attained dominance among the common materials due to their excellent properties that can be altered by adding different fillers. One of the main fillers is often based on silicon dioxide (SiO2). The concept of this study was to evaluate the effects of the selected silica-based fillers on the thermal, rheological, and mechanical properties of EMCs. Various types of fillers with SiO2, including crystalline silica and fused silica, were experimentally studied to clarify the impact of filler on final product. Fillers with different shape (scanning electron microscope, SEM), along with different specific surface area (spe...