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Wood–plastic composites (WPCs) are some of the most common modern composite materials for interior and exterior design that combine natural waste wood properties and the molding possibility of a thermoplastic polymer binder. The addition of reinforcing elements, binding agents, pigments, and coatings, as well as changes to the microstructure and composition, can all affect the quality of WPCs for particular purposes. To improve the properties, hybrid composite panels of WPCs with 30 wt. % and 40 wt. % of wood content and reinforced with one or three metal grid layers were prepared sequentially by extrusion and hot pressure molding. The results show an average 20% higher moisture absorption for composites with higher wood content. A high impact test (HIT) revealed that the absorbed energy of deformation increased with the number of metal grid layers, regardless of the wood content, around two times for all samples before water immersion and around ten times after water absorption. Also, absorbed energy increases with raised wood content, which is most pronounced in three-metal-grid samples, from 21 J to 26 J (before swelling) and from 15 J to 24 J (after swelling). Flexural tests follow the trends observed by HIT, indicating around 65% higher strength for samples with three metal grid layers vs. samples without a metal grid before water immersion and around 80% higher strength for samples with three metal grid layers vs. samples without a grid after water absorption. The synthesis route, double reinforcing (wood and metal), applied methods of characterization, and optimization according to the obtained results provide a WPC with improved mechanical properties ready for an outdoor purpose.

Polymer-bonded magnets are a class of composite material that combines the magnetic properties of metal particles and the molding possibility of a polymeric matrix. This class of materials has shown huge potential for various applications in industry and engineering. Traditional research in this field has so far mainly focused on mechanical, electrical or magnetic properties of the composite, or on particle size and distribution. This examination of synthesized Nd-Fe-B-epoxy composite materials includes the mutual comparison of impact toughness, fatigue, and the structural, thermal, dynamic-mechanical, and magnetic behavior of materials with different content of magnetic Nd-Fe-B particles, in a wide range from 5 to 95 wt.%. This paper tests the influence of the Nd-Fe-B content on impacting the toughness of the composite material, as this relationship has not been tested before. The results show that impact toughness decreases, while magnetic properties increase, along with increasing content of Nd-Fe-B. Based on the observed trends, selected samples have been analyzed in terms of crack growth rate behavior. Analysis of the fracture surface morphology reveals the formation of a stable and homogeneous composite material. The synthesis route, the applied methods of characterization and analysis, and the comparison of the obtained results can provide a composite material with optimum properties for a specific purpose.

This study investigates the effect of surface modification by deposition of electrospun fibers on properties and performance of three different microporous polypropylene/polyethylene (PP/PE) commercial nonwoven membrane supports (Novatexx 2430, 2465 and 2473). Polyamide (nylon 6) nanofiber webs with a small number of defects and fibers of about 100 nanometer diameter were successfully deposited onto a surface of the selected membrane supports. FESEM was used to examine microstructure and morphology of the unmodified substrates and the prepared composite two-layer membranes. DSC was applied to investigate thermal stability and FT-IR analysis to confirm the chemical composition of the studied membranes. Saline water permeability tests of the prepared two-layer composite membranes were carried out. The largest pressure difference was measured for PA nanofiber/Novatexx 2430 sample, which was ascribed to a denser net structure of the membrane support and possibly to the newly formed layer of dissolved salts on the membrane surface.

This study investigates the effect of surface modification by deposition of electrospun fibers on properties and performance of three different microporous polypropylene/polyethylene (PP/PE) commercial nonwoven membrane supports (Novatexx 2430, 2465 and 2473). Polyamide (nylon 6) nanofiber webs with a small number of defects and fibers of about 100 nanometer diameter were successfully deposited onto a surface of the selected membrane supports. FESEM was used to examine microstructure and morphology of the unmodified substrates and the prepared composite two-layer membranes. DSC was applied to investigate thermal stability and FT-IR analysis to confirm the chemical composition of the studied membranes. Saline water permeability tests of the prepared two-layer composite membranes were carried out. The largest pressure difference was measured for PA nanofiber/Novatexx 2430 sample, which was ascribed to a denser net structure of the membrane support and possibly to the newly formed layer of dissolved salts on the membrane surface.

In order to reduce negative influence of fossil fuels on environment, use of various renewable resources is highly promoted. Terpenes, naturally occurring in plants, can be added to petroleum fuel as its substitute up to a certain share. Thermodynamic properties of a fuel under high pressure and moderate temperature conditions are of significant importance for engine efficiency. This work reports density measurements of pure p-cymene, α-pinene, limonene and citral at temperatures (293.15–413.15) K and pressures (0.1–60) MPa, applying an Anton Paar DMA HP measuring cell. Density data were fitted by modified Tammann-Tait equation where the absolute average percentage deviation between measured and calculated densities was about 0.010%. The obtained parameters were used to estimate the isothermal compressibility, the isobaric thermal expansion coefficient, the internal pressure, and the difference between specific heat capacity at constant pressure and at constant volume. For examined compounds, all thermodynamic properties, except the internal pressure, decrease with pressure rise along an isotherm and increase as temperature increases at a constant pressure. The intersection point of isotherms for the isobaric thermal expansion coefficient for pure citral was registered at pressure 47 MPa, while for other analyzed terpenes the intersection point is above 60 MPa, outside the measurements pressure range.

In order to reduce negative influence of fossil fuels on environment, use of various renewable resources is highly promoted. Terpenes, naturally occurring in plants, can be added to petroleum fuel as its substitute up to a certain share. Thermodynamic properties of a fuel under high pressure and moderate temperature conditions are of significant importance for engine efficiency. This work reports density measurements of pure p-cymene, alpha-pinene, limonene and citral at temperatures (293.15-413.15) K and pressures (0.1-60) MPa, applying an Anton Paar DMA HP measuring cell. Density data were fitted by modified Tammann-Tait equation where the absolute average percentage deviation between measured and calculated densities was about 0.010%. The obtained parameters were used to estimate the isothermal compressibility, the isobaric thermal expansion coefficient, the internal pressure, and the difference between specific heat capacity at constant pressure and at constant volume. For examined compounds, all thermodynamic properties, except the internal pressure, decrease with pressure rise along an isotherm and increase as temperature increases at a constant pressure. The intersection point of isotherms for the isobaric thermal expansion coefficient for pure citral was registered at pressure 47 MPa, while for other analyzed terpenes the intersection point is above 60 MPa, outside the measurements pressure range.

This study presents preparation and characterization of ethyl cellulose based nanocomposites. Successful use of simple solvent casting technique provided nanocomposites with high loads of barium ferrite magnetic nanopowder in the polymer matrix, promising significant improvement of mechanical properties. Investigation of morphology revealed formation of agglomerates that are still on nanoscopic level. Nanocomposite thin films with a higher content of the magnetic powder showed substantial enhancement of break strength, elongation and microhardness compared to the pure ethyl cellulose, which was the primary aim of this research., Ова студија представља припрему и карактеризацију нанокомпозита на бази етил целулозе. Успешна употреба једноставне технике изливања обезбедила је нанокомпозите са великим уделом магнетног нанопраха баријум ферита у полимерној матрици, обећавајући значајно побољшање механичких својстава. Истраживањем морфологије откривено је формирање агломерата који су и даље на наноскопском нивоу. Нанокомпозитни танки филмови са већим садржајем магнетног праха показали су значајно повећање прекидне чврстоће, издужења и микротврдоће у поређењу са чистом етил целулозом, што је био главни циљ овог истраживања.

Hybrid composite panels of Wood-Plastic Composites (WPC) consisting of wood and poly (methyl methacrylate) (PMMA) were reinforced with alumina particles and made by “hot pressing” method. Alumina-based particles were made by sol-gel technique. The particles were characterized by the X-ray diffraction (XRD). The resulting alumina particles were modified with (3mercaptopropyl) trimethoxysilane (MPTMS), in order to obtain better mechanical properties of the composite relative to the composite with unmodified alumina particles. The aim of this work was to study the influence of composite structure and the moisture absorption on bending and the impact properties of the hybrid composite. The bending and impact tests revealed that modulus of elasticity and absorbed energy of deformation increased with modification of alumina and slightly decrease after moisture absorption., Хибридни композитни панели дрво-пластика композит (ДПК) који се састоје од дрвета и поли(метил метакрилата) (ПММА) ојачани честицама алуминијум оксида прецесирани методом „врућег пресовања“. Честице засноване на алуминијум оксиду направљене су сол – гел техником. Карактеризација честица вршена је рендгенском анализом. Добијене честице алуминијум оксида модификоване су помоћу (меркаптопропил)триметоксисилана, како би се постигла боља механичка својства композита у односу на композит са немодификованим честицама алуминијум оксида. Циљ овог рада је проучавање утицаја структуре хибридног композита и апсорбоване влаге на механичка својства, савијање и контролисани удар. Тестови савијања и удара показали су да се модул еластичности и апсорбована енергија деформације повећава модификацијом алуминијум оксидних честица, а незнатно самањује након апсорпције влаге.

Hybrid composite panels of Wood-Plastic Composites (WPC) consisting of wood and poly (methyl methacrylate) (PMMA) were reinforced with alumina particles and made by "hot pressing" method. Alumina-based particles were made by sol-gel technique. The particles were characterized by the X-ray diffraction (XRD). The resulting alumina particles were modified with (3mercaptopropyl) trimethoxysilane (MPTMS), in order to obtain better mechanical properties of the composite relative to the composite with unmodified alumina particles. The aim of this work was to study the influence of composite structure and the moisture absorption on bending and the impact properties of the hybrid composite. The bending and impact tests revealed that modulus of elasticity and absorbed energy of deformation increased with modification of alumina and slightly decrease after moisture absorption.

Prikazani rezultat - novo laboratorijsko postrojenje za određivanje separacionih karakteristika membrana od značaja je za proširivanje asortimana uređaja namenjenim testiranju membrana za separaciju gasova koji može biti konkurentan ne samo na domaćem, već i na svetskom tržištu. Korišćenjem predloženog uređaja, dobijaju se neophodni podaci o permeabilnosti i selektivnosti polimernih nanokompozitnih membrana. Pored efikasnosti i preciznosti merenja, predloženi uređaj nudi prednost jednostavne konstrukcije, prenosivosti i modularnosti.

In this study, electrospinning combined with sol-gel technique is applied in order to produce magnetic nickel ferrite (Ni-ferrite) nanofibers. The prepared Ni-ferrite gel was mixed with poly(vinylpyrrolidone) (PVP) solution which was used as a spinning aid to enable spinnability of the mixture. Structural and morphological characteristics of the asspun ferrite gel/PVP composite web structure and calcinated Ni-ferrite nanofibers were analyzed using scanning electron microscopy (SEM). Phase composition analysis was carried out by Fourier-transform infrared (FT-IR) spectroscopy, X-Ray diffraction analysis (XRD) and Fe-57 Mossbauer spectroscopy (MS). The obtained results suggest that the pure nanocrystalline NiFe2O4 dense mat to the almost coral-like structure of fibers with diameters ranging from hundreds of nanometers to few micrometers was obtained. The results of MS analysis revealed the existence of a crystallite size distribution within the material as well as the existence of a superparamagnetic fraction with very small crystallite sizes (<13nm). Magnetic behavior of the obtained material at elevated temperatures was also scrutinized using thermomagnetic measurements (TM) up to 800 degrees C.

Continuous catalytic reforming (CCR) is known to convert refinery naphtha to a high-octane liquid product, also known as the reformate. In this paper, a First Principle Reaction Section Model for a CCR process is presented. Even though CCR is a well-established technology, the application of advanced, real-time optimization techniques that are able to quickly respond to any imposed changes onto the process, are necessary in the refinery business. This becomes particularly important as a result of changes in profit margin, changes in operating cost, and the introduction of new environmental legislations. Hence, we present a kinetic model for the CCR process using the so-called "lumped" concept. The reactors have been modeled using a quasi-steady-state approach. The unknown model parameters have been estimated by bench marking the First Principle Reaction Section results with a commercial CCR process owned by the Hungarian Oil and Gas Public Limited Company (INA-MOL). The proposed model has been tested and compared to data obtained from an existing CCR plant. The predictions of the model were found to be in good agreement with the experimental data. The relative absolute errors between the measured and model estimated variables have been found to be lower than 2%. The relative absolute error associated with the required fired heater duties were less than 1.0%. Simulating the reaction section of the CCR process requires less than 0.1 s of CPU time, which clearly indicates that this model can be very suitable for performing optimization studies. Moreover, this study shows that, although there is fluctuation in the composition of feedstock, the lumped kinetic approach was capable to predict the behavior of the CCR process well.

This study presents the route for preparation of the membrane-supporting materials with good mechanical behavior and adsorption properties that provide functionality and are easy to use in various environments. Polyethersulfone (PES) membrane-supported hydrogels were prepared via liquid phase inversion process with photopolymerization and monomer crosslinking. The obtained membranes had asymmetric structure containing dense skin on the top of a porous hydrogel as it is verified by scanning electron microscopy. Software analysis of the pore size revealed that fine pores enabled availability of the membrane active centers to metal cations. The membranes with a higher content of the polymer showed significantly improved mechanical properties compared with commonly used ion exchange membranes, which is crucial for the wastewater treatment application. Adsorption kinetics analysis showed that the hydrogel-rich bottom layer has significantly higher adsorption ability in comparison to the top layer. Adsorption kinetics of the bottom side was described by the first-order kinetics model, whereas for the the top side, phase-boundary controlled reaction model was used.

This work presents a systematic approach toward the design of Organic Rankine Cycles (ORC) for the generation of power from multiple heat sources available at different temperature levels. The design problem is approached in a mixed-integer non-linear programming (MINLP) formulation where an inclusive and flexible ORC model is automatically evolved by a deterministic algorithm for global optimization. The basic building block of the model is the ORC cascade which consists of a heat extraction, a power generation, a condensation and a liquid pressurization section. The aim of the optimization is to determine the optimum number of ORC cascades, the structure of the heat exchanger network shared among different cascades, the operating conditions and the working fluid used in each cascade in order to identify an overall ORC structure that maximizes the power output. The approach is illustrated through a case study which indicates that a system of two waste heat sources is best exploited through two interconnected ORC utilizing different working fluids.

The Nd-Fe-B-barium ferrite hybrid composite materials with epoxy matrix presented in this paper cover maximum energy product from 1 to 13 MGOe. Mixture of magnetic particles is responsible for high magnetic quality, while the thermosetting resin plays a role in mechanical properties. Samples with various ratio of Nd-Fe-B to barium ferrite in constant weight of epoxy resin are examined by tensile strength measurements. Magnetic measurements carried out by using vibrating sample magnetometer (VSM) show typical hysteresis loop. A structural analysis of composite surface is conducted by scanning electron microscope (SEM). Uniform particle distribution of plate shape Nd-Fe-B particles and spherical barium ferrite agglomerates is essential for both, mechanical and magnetic properties of composite materials. Fine particles are incorporated in-between larger particles in epoxy bulk which lead to improving the properties., U ovom radu proučavani su hibridni Nd-Fe-B-barijum ferit kompozitni materijali sa epoksi matricom čiji se maksimani energetski proizvod kreće od 1 do 13 MGOe. Odlična magnetna svojstva kompozita potiču od smeše magnetnih čestica, dok termoočvršćavajući polimer ima uticaj na mehanička svojstva. Uzorci sa različitim odnosom udela Nd-Fe-B i barijum ferita u konstantnoj masi epoksi veziva su ispitivani na zateznu čvrstoću. Magnetna merenja vršena pomoću vibracionog magnetometra (VSM) pokazuju karakteristučnu histerezisnu petlju. Strukturnu analizu na površini kompozita sprovedena pomoću skenirajuće elektronske mikroskopije (SEM). Uniformna raspodela pločastih Nd-Fe-B čestica i sferičnih aglomerata barijum ferita je veoma značajna i za mehanička i za magnetna svojstva kompozitnih materijala. Sitne čestice su inkorporirane između velikih čestica u masi epoksida što dovodi do poboljšanja svojstava.

We propose a systematic model for the optimum design of Organic Rankine Cycles (ORC) used for power generation from multiple heat sources available at different temperatures. The model enables the automated generation of inclusive and flexible ORC cascades and is optimized using a global optimization algorithm. Design parameters include the number of ORC cascades, the shared structure of the heat exchanger network, the operating conditions and the working fluid used in each cascade in order to identify an overall ORC structure that maximizes the power output. Results indicate significant operating improvements from using a double ORC cascade with different working fluids.

We propose a systematic model for the optimum design of Organic Rankine Cycles (ORC) used for power generation from multiple heat sources available at different temperatures. The model enables the automated generation of inclusive and flexible ORC cascades and is optimized using a global optimization algorithm. Design parameters include the number of ORC cascades, the shared structure of the heat exchanger network, the operating conditions and the working fluid used in each cascade in order to identify an overall ORC structure that maximizes the power output. Results indicate significant operating improvements from using a double ORC cascade with different working fluids.