Bela Pukanszky

• Budapest University of Technology and Economics

Nanosized hydroxyapatite (HAP) particles were produced by precipitation, and poly(lactic acid) (PLA) composites containing 5 wt% of the nano HAP were prepared in an internal mixer to prepare scaffold materials. The nanoparticles aggregated without surface modification. Applying stearic acid coating on HAP particles decreased aggregation and improve...

Utilizing the electrospinning technique to entrap enzymes within nanofibers (providing nanofibrous enzyme catalysts, NEC) offers promising avenues for the scientific and industrial sectors as well. While numerous instances of poly(vinyl alcohol) (PVA)‐based nanofibrous biocatalysts have been documented, a comprehensive investigation to characterize...

Electrospun fibers prepared from water-soluble polymers (PVP, PVA, and HPMC) were loaded with pregabalin, a BCS I drug, to address its fast release and adverse effects. The drug dissolved partially (1.8–2.8 wt%) in the polymers, with excess pregabalin in crystalline form within the fibers. The solubility of the drug varied with the pH of the dissol...

The goal of this project was to recycle the waste forming in the production of a flexible, multilayer food packaging film. The film consists of five layers, two polyamides containing three different polymers, a polyethylene and two adhesive layers of maleated polyethylene. The type of the components and the exact composition are not disclosed becau...

Polypropylene (PP) hybrid composites were prepared with talc, a reinforcing filler, and an additional impact modifier. Impact resistance was improved by the use of a traditional elastomer and by the new approach of adding a synthetic polymer fiber, poly(vinyl alcohol) (PVA), in this case. The results showed that the use of PVA is more efficient tha...

Poly(butylene adipate-co-terephthalate) (PBAT) was added to poly(lactic acid) (PLA)/lignin blends to decrease the considerable stiffness and brittleness of the blends. Two- and three-component blends were prepared in a wide composition range through homogenization in an internal mixer followed by compression molding. Interactions among the componen...

Electrospun fibers containing levocetirizine, a BCS III drug, were prepared from three water-soluble polymers, hydroxypropyl methylcellulose (HPMC), polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA). Fiber-spinning technology was optimized for each polymer separately. The polymers contained 10 wt% of the active component. An amorphous drug was...

The agglomeration tendency of 11 commercial CaCO 3 fillers with different particle size and specific surface area was investigated with various techniques. Some powder characteristics were measured and also the sedimentation of treated, as well as non-treated fillers were determined in water and toluene. PP composites containing 25 vol% filler were...

Dry grape peel powder was extracted by three different techniques, stirred tank reactor, Soxhlet and ultrasound extraction. The composition, physical and chemical structure and inherent stability of the extracts were characterized by various methods. The extracts and reference compounds were added to polyethylene and their stabilization efficiency...

Polypropylene (PP)/elastomer/wood flour composites were prepared from two PP reactor blends. The detailed analysis of the deformation and failure of the composites have shown that several local deformation processes take place during loading which differ considerably in terms of energy consumption. These processes may even interact with each other,...

The enzymatic degradation of aliphatic polyesters is often hindered by the decrease of pH with time. The phenomenon is caused by the formation of the monomer and other oligomers in the aqueous medium, which are weak acids and partially dissociate. The effect is especially pronounced during the degradation of poly(lactic acid) (PLA). Although lactic...

Poly(lactic acid)/regenerated cellulose nanocomposites have been prepared by the Pickering emulsion approach. The composites contained 0, 0.5, 1.0, 1.5, 2.0 and 3.0 wt% nanocellulose. Plates compression molded from the composites were degraded enzymatically by Proteinase K with the daily change of the degradation medium. The results confirmed the e...

Poly(lactic acid) (PLA) was modified by the addition of synthetic polymer fibers, poly(ethylene terephthalate) (PET) and poly(vinyl alcohol) (PVA) to improve its stiffness and impact resistance. Wood flour was used as reference in the study. The results showed that polymer fibers improve stiffness moderately and impact strength considerably compare...

The concept of adding synthetic polymer fibers for the impact modification of poly(lactic acid) (PLA) was investigated in this study. Poly(ethylene terephthalate) (PET) and poly(vinyl alcohol) (PVA) fibers were used as impact modifiers, while wood flour as reference. Polymer fibers increase stiffness moderately but fracture resistance considerably....

Polypropylene composites were prepared with a new, commercially available hybrid nanofiller and talc as a reference. The detailed analysis of the nanofiller proved that its two components are sepiolite and possibly laponite and that it was surface coated with an ammonium ion having long aliphatic chains. The results showed that the concept of hybri...

Biocomposites were prepared from poly(lactic acid) and two natural reinforcements, a native starch and sugarcane bagasse fibers. The strength of interfacial adhesion was estimated by model calculations, and local deformation processes were followed by acoustic emission testing. The results showed that the two additives influence properties differen...

PLA fibers containing metronidazole as the active component were produced by electrospinning from a solvent mixture of dichloromethane (DCM) and dimethyl sulfoxide (DMSO). The DMSO content of the spinning solution changed between 0 and 25 vol% in 5 vol% steps. The fibers were dried at different temperatures, and processes taking place during fiber...

Hybrid composites were prepared from a polypropylene reactor blend (rPP), lignin and flax fibers. Interfacial adhesion was improved using a functionalized PP (maleated PP, MAPP) coupling agent. Composition changed in a wide range; flax content varied between 0 and 30, while lignin content between 0 and 50 vol% in 10 vol% steps. The components were...

A new phosphine-type potential secondary stabilizer was synthesized successfully with large natural raw material content. The stabilizer is a waxy white powder with a relatively low melting temperature. Both the thermal and the storage stability of the stabilizer are sufficient for practical use. The new stabilizer was introduced into a Phillips-ty...

Flax and lignin were used to prepare hybrid polypropylene composites. The lignin contents were varied between 0 and 50 vol%, while the amounts of flax used were 0, 10, 20, and 30 vol%. The components were homogenized in a twin-screw compounder and then injection molded into tensile bars. Tensile and impact tests were used to characterize the mechan...

A new method is proposed in this article which is based on fractionation and results poly(3-hydroxybutyrate) particles of nearly monodisperse size distribution. This kind of separation is achieved by taking advantage of the phenomenon that the movement of particles triggered by a constant force in a homogeneous fluid have a velocity depending on th...

The enzymatic degradation of poly(lactic acid) was catalyzed with Proteinase K and the effect of various factors on the rate of degradation was analyzed quantitatively with the help of appropriate kinetic models. The Michaelis-Menten model was modified for the purpose by considering the heterogeneous nature of the reaction and the denaturation of t...

Dry pomegranate peel was extracted with acetone and the extract was added to a Phillips type polyethylene. The concentration of the extract was changed from 0 to 1000 ppm in six steps and stabilization efficiency was checked by the multiple extrusion of the polymer followed by the characterization of chemical structure, processing, and residual sta...

Polypropylene (PP) hybrid composites were prepared by the combination of three reinforcing (carbon, glass, and wood) and a synthetic (PVA) fiber. Tensile and impact testing, acoustic emission measurements, and scanning electron microscopy (SEM) were used for the characterization of the composites as well as to follow deformation and failure process...

In an attempt to improve the solubility of valsartan, a BCS II drug, fibers containing the drug were prepared from three water-soluble polymers, hydroxypropyl-methyl-cellulose (HPMC), polyvinyl-pyrrolidone (PVP), and polyvinyl-alcohol (PVA). Fiber spinning technology was optimized for each polymer separately. The polymers contained 20 wt% of the ac...

A model study on isotactic polypropylene (iPP) films as commonly used in packaging was performed for simulating the process of microplastics formation from large-scale objects like littered packaging material,. Accelerated ultraviolet (UV) ageing in a Xenotest device resulted in chemical degradation and oxidation of the polymer, together with fragm...

Acoustic emission, the detection of signals during deformation, is a frequently used method for the study of local deformation processes occurring in heterogeneous polymer systems. Most of these processes result in the evolution of elastic waves which can be detected by appropriate sensors. The analysis of several parameters characterizing the wave...

Polycaprolactone (PCL)/halloysite composites were prepared to compare the effect of homogenization technology on the structure and properties of the composites. Halloysite content changed from 0 to 10 vol% in six steps and homogeneity was characterized by various direct and indirect methods. The results showed that the extent of aggregation depends...

Active components with antioxidant activity were extracted from the powder of pomegranate peel and added to polyethylene at 1000 ppm. The stabilization effect of the extract was studied also in compounds containing a phosphorous secondary antioxidant. A commercial hindered phenolic antioxidant with and without a secondary stabilizer was used as ref...

Fibers were spun from a mixture of dichloromethane (DCM) and dimethyl sulfoxide (DMSO) solution of poly(lactic acid)(PLA) containing various amounts of amoxicillin (Amox) as the active component. Composition changes during spinning, structure, solubility, and the location of the drug were considered during the evaluation of drug release and microbi...

Immobilization of the recombinant, plant-derived Petroselinum crispum phenylalanine ammonia lyase (PcPAL) in electrospun matrices have the potential to create promising, easy-to-use biocatalysts. Polylactic acid (PLA) a biologically inert, commercial biopolymer, was chosen as the material of the carrier system. PLA could be electrospun properly onl...

Hybrid composites were prepared from a PP homopolymer, talc and PVA fibers by twin-screw extrusion and injection molding. Talc was added to improve stiffness, while the fibers serve to increase impact resistance. Mechanical properties were characterized by tensile and impact testing, while structure was studied by SEM and optical microscopy. The re...

The internal plasticization of cellulose acetate (CA) was achieved by grafting with ε-caprolactone (CL) via reactive processing. The effect of varying concentrations of tin(II) bis(2-ethylhexanoate) [Sn(Oct)2] and iron(III) acetylacetonate [Fe(Acac)3] catalysts on the ring-opening polymerization (ROP) of CL were compared with each other. The analys...

Polypropylene (PP) hybrid composites were prepared by the combination of natural reinforcements and poly(ethylene terephthalate) (PET) fibers. Wood, flax, and sugar palm fibers were used to increase stiffness and strength, while PET fibers served to improve impact resistance. Interfacial adhesion was increased by using a maleated PP (MAPP) coupling...

PP/sugarcane bagasse fiber composites were prepared by injection molding from two fractions of fibers with different particle characteristics. The mechanical properties of the composites were characterized by tensile and impact measurements, while local deformation processes by acoustic emission testing and microscopy. The determination of fiber di...

PLA/regenerated cellulose (RC) nanocomposites containing 0.5, 1.0, 1.5, 2.0, 3.0 and 5.0 wt% cellulose were prepared by the Pickering emulsion process. The structure and the rheological properties of the composites were characterized by microscopy, the measurement of melt flow rate and oscillatory rheometry. Viscosity was modelled with the modified...

Polypropylene (PP) hybrid composites were prepared by the combination of traditional reinforcements (wood, glass, carbon) and poly(ethylene terephthalate) (PET) fibers. Interfacial adhesion was improved by the use of maleated PP (MAPP). The composites contained 20 wt% of the traditional reinforcement and the amount of PET fiber changed from 0 to 40...

PLA/sugarcane bagasse fiber composites were prepared by injection molding from two fractions of fibers with different fiber characteristics, which were determined before and after processing. Interfacial adhesion was modified by a maleated PLA coupling agent. The mechanical properties of the composites were characterized by tensile and impact testi...

Ionomers with different degree of neutralization were prepared from an ethylene-acrylic acid copolymer of 8.5 wt% acrylic acid content. The ionomers were characterized by Fourier transform infrared spectroscopy, small angle X-ray scattering, differential scanning calorimetry and dynamic mechanical thermal analysis measurements as well as rheology a...

This work presents the immobilization of cinchona squaramide organocatalysts on poly(glycidyl methacrylate) solid supports. Preparation of the well‐defined monodisperse polymer microspheres was facilitated by comprehensive parameter optimization. By exploiting the reactive epoxy groups of the polymer support, three amino‐functionalized cinchona der...

Composites were prepared from a polypropylene homopolymer and four types of organic fibers, wood, flax, poly(ethylene terephthalate) (PET) and poly(vinyl alcohol) (PVA). Mechanical properties were studied by tensile and impact testing, and structure by scanning electron microscopy. Local deformation processes were followed by acoustic emission test...

Poly(lactic acid) (PLA) and thermoplastic starch (TPS) blends with two different glycerol contents were prepared by injection molding. Mechanical properties were characterized by tensile and impact testing, structure by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) as well as Raman spectroscopy, and water absorption was dete...

Polypropylene composites were prepared from neat and alkali-treated sugarcane bagasse fibers. The results showed that alkali treatment leads to an increase in composite stiffness and strength. A maximum is achieved in these properties at around 5 wt% NaOH content of the treating solution. The increase in properties was assigned to the improvement i...

A fibrous scaffold was prepared from poly(3-hudroxybutirate) (PHB) by wet spinning from chloroform solution. The fibers were precipitated into excess ethanol and they had a regular, cylindrical shape. The diameter of the fibers was regulated by the rate of spinning. A model drug, quercetin, was dissolved in the fiber in various amounts. The rate of...

Long PMMA chains were successfully attached to the surface of laponite layers through the [2-(acryloil-oxy)-ethyl]-trimethylammonium chloride linker. Grafting was carried out in water and the molecular weight of the grafted polymer changed between 40 and 110 kDa. The amount of PMMA attached to the silicate and the length of the polymer depended on...

The efficiency of the natural extract, silymarin, was compared to its main component, silybin in the processing stabilization of polyethylene. The two compounds were applied as primary antioxidants in the concentration range of 0–500 ppm in combination with 1000 ppm Sandostab PEPQ phosphorous secondary stabilizer. The efficiency of the stabilizers...

A polypropylene (PP) homopolymer was reinforced with carbon fiber, glass fiber and wood flour in order to compare their advantages and drawbacks. Interfacial adhesion does not influence stiffness, but it affects strongly properties, i.e. tensile strength and impact resistance. Several local deformation and failure processes take place simultaneousl...

Lignocellulosic fibers extracted from sugarcane bagasse were treated with NaOH solutions of different concentration (0-40 wt%) to study the effect of alkali treatment on the composition, structure and properties of the fibers. Composition was determined by the van Soest method, structure was characterized by X-ray diffraction (XRD) and scanning ele...

Two polypropylene polymers with considerably differing properties were modified with poly(ethylene terephthalate) (PET) and poly(vinyl alcohol) (PVA) fibers. Fiber content changed from 0 to 60 vol% and interfacial adhesion was modified with the addition of a maleated PP coupling agent. Mechanical properties were characterized by tensile and impact...

Purpose Electrospun PLA fiber devices were investigated in the form of fiber mats and disks. Metronidazole was used as an active agent; its concentration was 12.2 and 25.7 wt% in the devices. Methods The structure was studied by X-ray diffraction and scanning electron microscopy, drug release by dissolution measurements, while the antimicrobial ef...

The enzymatic degradation of poly (lactic acid) (PLA) and its nanocomposites reinforced with cellulose nanocrystals (CNC) was catalyzed with lipase from Candida rugosa and proteinase K from Tritirachium album. The composites were prepared with the Pickering emulsion process and they contained 5, 10 and 15 wt% nanocellulose. Compression molded plate...

Injection molded specimens were prepared from poly(lactic acid) (PLA) and their properties were determined as a function of time to study physical ageing. The mechanical testing of specimens showed that properties change rapidly with time. The stiffness of the specimens increases considerably, while their deformability decreases drastically from 25...

A lipase from Burkholderia cepacia was successfully adsorbed on the surface of halloysite nanotubes and the coated tubes were incorporated into poly-ε-caprolactone (PCL). The efficiency of the halloysite in the adsorption of the enzyme was characterized by the total protein content determined with the Bradford method. The activity of the adsorbed e...

A simple method is proposed for the determination of the release kinetics of small molecular weight drugs from amorphous PHB. The method uses the hipsochromic shift of the absorbance of active molecules caused by changes in the UV–Vis spectra as an effect of changing environment. Fuchsine with a strong hypsochromic shift was used as model drug in t...

The use of nanocellulose is an attractive method to improve the characteristics of biodegradable polymers, but its effects are often affected by uneven dispersion. In this work, cellulose nanocrystals (CNCs) were evenly dispersed into poly(lactic acid) (PLA) via the Pickering emulsion approach. The PLA/CNC composites prepared were studied by rheolo...

The edges of a synthetic layered silicate, Laponite XLG, was successfully modified with various amounts of ethoxytrimethylsilane, a monofunctional silane compound. The occurrence of the reaction was confirmed with various techniques. Thermogravimetric measurements and Fourier-transform infrared spectroscopy (FTIR) carried out on both the treated fi...

The impact resistance of polypropylene (PP)/wood composites was improved either by the traditional approach of adding an elastomer or by the use of poly(ethylene terephthalate) (PET) fibers. Composites were prepared with various elastomer and PET fiber contents at a constant wood content of 20 wt% for all hybrid composites. Interfacial adhesion was...

In this work, the Pickering emulsion template method was used to introduce lignin nanoparticles into poly(lactic acid) (PLA) with improved dispersion. The effect of lignin as the stabilizer of Pickering emulsions was studied in this paper, including the thermal, rheological and mechanical properties of the blends. The PLA/lignin films had reduced l...

The two-step stabilization of a thoroughly characterized PAN homopolymer was studied by various methods including thermogravimetric analysis (TGA), evolved gas analysis (EGA), differential scanning calorimetry (DSC), Fourier transformed infrared spectroscopy (FTIR), oxygen microanalysis and theoretical energy calculations. Stabilization was carried...

Polypropylene composites were prepared from sugarcane bagasse fibers by extrusion and injection molding. Wood flour was used as reference filler in the study. The fiber content of the composites changed between 0 and 30 wt% in 5 wt% steps. Maleated polypropylene was used as coupling agent to improve interfacial adhesion. Mechanical properties were...

Blends were prepared from lignin and ethylene-vinyl alcohol (EVOH) copolymers to study the effect of component interactions and composition on structure. The vinyl alcohol (VOH) content of the polymers changed between 0 and 76 mol%, while the lignin content of the blends varied between 0 and 60 vol%. Low density polyethylene (LDPE) with 0 mol% VOH...

Composites were prepared from three traditional microfillers, glass beads (GB), wood flour (WF) and glass fibers (GF), as well as sodium montmorillonite (NaMMT) and an organophilic clay (OMMT) in a polyamide (PA) matrix in order to compare their properties and discuss the benefits and drawbacks of using micro- or nanofillers. Structure was characte...

The enzyme catalyzed degradation of poly(3-hydroxybutyrate) (PHB) is a two-step process consisting of the adsorption of the enzyme on the surface of a PHB substrate and the cleavage of ester bonds. A deactivated enzyme was prepared by point mutagenesis to separate the two steps from each other. Measurements carried out with active and inactive enzy...

Blends were prepared from an industrial lignosufonate and seven matrix polymers with different chemical structures. The components were homogenized in an internal mixer and plates were compression molded for further testing. The blends were characterized by a number of methods: structure by scanning electron microscopy, interactions by dynamic mech...

The stabilization effect of a flavonoid type natural antioxidant, rutin, was compared to that of quercetin in polyethylene. Additive concentrations changed between 0 and 500 ppm in several steps and also 1000 ppm Sandostab PEPQ phosphorus secondary stabilizer was added to each compound. Stabilization efficiency was determined by changes in vinyl gr...

Blends were prepared from lignin and ionomers, i.e. ethylene-methacrylic acid copolymers partially neutralized with inorganic salts for the first time in order to check the possible effect of ionic bonds on the structure and properties of the blends. A low density polyethylene and an ethylene-acrylic acid copolymer without any neutralization were u...

A polyacrylonitrile (PAN) homopolymer and a copolymer with methyl acrylate were analyzed by differential scanning calorimetry (DSC) in order to establish a method for the kinetic analysis of the stabilization reaction steps during heat treatment. The application of a program rarely used for the study of the chemical transformation of PAN and its co...

Desiccant composites were prepared from seven high impact polystyrene copolymers (HIPS) with different butadiene content and dispersed droplet size to study the effect of structure on their functional and application properties. A 4A type zeolite was used as desiccant. The thermodynamic analysis of structure development revealed that the embedding...

Poly-[(R)-3-hydroxybutyrate] (PHB) films prepared by compression molding and solvent casting, respectively, were degraded with the intracellular depolymerase enzyme natively synthetized by the strain Bacillus megaterium. Quantitative analysis proved that practically only (R)-3-hydroxybutyric acid (3-HBA) forms in the enzyme catalyzed reaction, the...

A natural antioxidant, quercetin, was adsorbed on the surface of halloysite nanotubes in various amounts to prepare a controlled release device. The combined additive was added to polyethylene providing antioxidant levels of 250, 500, 750 and 1000 ppm. All polymer samples contained 1000 ppm Sandostab PEPQ phosphonite secondary antioxidant as well....

A segmented polyurethane elastomer (PU) was synthesized in poly(lactic acid) (PLA) melt by reactive processing. The isocyanate component was anticipated to react with the end-groups of PLA resulting in the formation of block-copolymers. The stoichiometry of the functional groups was optimized in the preliminary experiments. Two different processing...

The specific surface area of three layered silicates was determined by three independent methods; it was estimated from the average dimensions of individual silicate layers, determined by nitrogen adsorption using the BET model and calculated from the adsorption of methylene blue on their surface in aqueous sol. The BET model gave smaller surface a...

Blends were prepared from lignin and ethylene-vinyl alcohol (EVOH) copolymers to study the effect of hydrogen bonding interactions on compatibility and structure. The vinyl alcohol (VOH) content of the copolymers changed between 52 and 76 mol%, while the lignin content of the blends varied between 0 and 60 vol%. Low density polyethylene with 0 mol%...

A novel approach is proposed for the determination of the diffusion coefficient of certain drugs in amorphous poly(hydroxybutyrate) (PHB), which can be a reliable alternative to the conventional permeation based measurements. The method requires the preparation of PHB films with various concentrations of the drug and if the latter absorbs in the vi...

The additive packages routinely used today usually consist of a phenolic antioxidant and a phosphorus or sulfur containing secondary stabilizer. Several years ago some questions were raised about the health and environmental hazard of these additives and industry has not offered an alternatively solution yet. Nature produces a large number of antio...

Thermoplastic polymer/layered silicate composites were prepared from the same organophilized montmorillonite (OMMT) and four different matrices, polypropylene (PP), the blend of PP and a maleated polymer (MAPP), poly(lactic acid) (PLA) and polyamide (PA) in order to study the effect of their chemical structure and interactions on composite structur...

Amorphous poly(3-hydroxybutyrate) films prepared by compression molding and solvent casting were degraded in aqueous media at different pH values. The time dependence of degradation was monitored by the measurement of weight loss, the extraction of the degradation products from the degrading sample, as well as by UV-Vis spectrophotometry and HPLC a...

Lignin is a cheap material available in large quantities, thus the interest in its valorization is increasing both in industry and academia. A possible approach towards value added applications is using it as a component in plastics. However, blending lignin with polymers is not straightforward because of the polarity of lignin molecules resulting...

Although particulate-filled polymer composites are mature materials with a long history of application, their structure–property correlations are more complicated than usually assumed. The characteristics of all heterogeneous polymer systems including composites containing micro- or nanofillers are determined by four factors: component properties,...

The stabilization effect of two flavonoid type natural antioxidants, silymarin (Si) and quercetin (Q), was compared in polyethylene (PE). Additive concentrations changed between 0 and 500 ppm in several steps and 1000 ppm Sandostab PEPQ phosphorus containing secondary stabilizer was also added to each compound. Stabilization efficiency was determin...

A novel method was introduced for the quantitative determination of substances in aqueous solutions by using the evaporative light scattering (ELS) detector of a high performance liquid chromatograph (HPLC). The principle of the measurement is the different equilibrium vapor pressure of the solvent and the analyte resulting in decreasing evaporatio...

The use of mineral fillers increases continuously. The incorporation of the filler into the polymer results in new materials. The properties of these composites are determined by the characteristics of the components, composition, interfacial interactions, and structure. Both aggregation and orientation of anisotropic filler particles affect strong...

Ten different polymers were selected as possible matrices for zeolite containing desiccant composites in order to prepare functional packaging material. A 5A type zeolite was used as desiccant. Composites containing the zeolite up to 50 vol% were prepared. Interfacial adhesion was estimated by various means including the measurement of surface char...