Gas Separation Properties of the Dense Polymer-Zeolite Powder Composite Membranes

The natural balance in the Earth's atmosphere is significantly influenced by the human emission of the combustion products, mainly carbon dioxide. Therefore, strong efforts are directed in the direction of the reduction of that emission. The solution might be searched in the direction of the construction of the membrane that would be highly transparent to the carbon dioxide, but not transparent to the other gases commonly present in the waste gases (oxygen, nitrogen, hydrogen, methane). One of the feasible designs for this purpose is dense, non-porous membranes, with zeolite particles dispersed in the polymer matrix. Zeolite particles should increase the solubility of the carbon dioxide, and thus enhance its permeability. In this paper, the possibility of application of polyether-b-amide (with 60% of PEG) as a polymer matrix was tested. For the inorganic component, four different zeolite types with three different pore geometries were tested. The influence of the additive which was added in order to provide good contact between the highly polar and charged zeolite inorganic particle, and hydrophobic polymer chains was also tested

Poređenje metoda za merenje propustljivosti vazduha tekstilnih materijala

The air permeability of textile fabrics is defined as the air passed over a surface under a certain pressure difference in a unit time. Air permeability is often used in evaluating the performance of clothing textiles and technical textiles such as air bags, sail cloth, parachutes sails and industrial textile filters. In practice, which does not have to include scientific research, it is necessary that all tests of textile materials are carried out according to the standards. In the case of air permeability, the most commonly used standard methods are ASTM D737 and ISO 9237 standards. The values of the tested property of a textile material vary very often depending on the device used and method applied. In this research, a comparison of the results of air permeability of some plain knitted fabrics was made, which were obtained using two different devices according to ASTM D737 and ISO 9237 methods. The results obtained indicated the differences in the values of air permeability for all the knitted fabrics. However, the same trend was observed in terms of the observed differences which was confirmed by the high value of the correlation coefficient (r=0.98).Propustljivost vazduha tekstilnih materijala definiše se količinom vazduha koji pri konstantnom pritisku u jedinici vremena prođe kroz jedinicu površine materijala. Ovaj parametar se često koristi za ocenjivanje performansi odevnih tekstilnih materijala i tehničkog tekstila kao što su tkanine za vazdušne jastuke, jedra i padobrane, i industrijski tekstilni filteri. U stručnoj praksi, koja ne uključuje obavezno naučna istraživanja, neophodno je da se sva testiranja tekstilnih materijala vrše prema normama propisanim važećim standardima. Propustljivost vazduha tekstilnih materijala najčešće se ispituje standardnim metodama ASTM D737 i ISO 9237. Vrlo često se dešava da se kvantifikovane vrednosti ispitivanog svojstva tekstilnog materijala razlikuju u zavisnosti od upotrebljenog uređaja, odnosno primenjene standardne metode. Zbog toga je u okviru ovog istraživanja izvršeno poređenje rezultata propustljivosti vazduha grupe DL pletenina, koji su dobijeni primenom dva različita uređaja i dve standardizovane (ASTM D737 i ISO 9237) metode. Poređenjem dve grupe rezultata propustljivosti vazduha DL pletenina uočene su razlike u vrednosti ovog parametra kod svih ispitivanih pletenina. Ipak, zapažen je isti trend u pogledu uočenih razlika u propustljivosti vazduha pletenina, što je potvrđeno visokom vrednošću koeficijenta korelacije (r=0,98)

Poređenje metoda za merenje propustljivosti vazduha tekstilnih materijala

The air permeability of textile fabrics is defined as the air passed over a surface under a certain pressure difference in a unit time. Air permeability is often used in evaluating the performance of clothing textiles and technical textiles such as air bags, sail cloth, parachutes sails and industrial textile filters. In practice, which does not have to include scientific research, it is necessary that all tests of textile materials are carried out according to the standards. In the case of air permeability, the most commonly used standard methods are ASTM D737 and ISO 9237 standards. The values of the tested property of a textile material vary very often depending on the device used and method applied. In this research, a comparison of the results of air permeability of some plain knitted fabrics was made, which were obtained using two different devices according to ASTM D737 and ISO 9237 methods. The results obtained indicated the differences in the values of air permeability for all the knitted fabrics. However, the same trend was observed in terms of the observed differences which was confirmed by the high value of the correlation coefficient (r=0.98).Propustljivost vazduha tekstilnih materijala definiše se količinom vazduha koji pri konstantnom pritisku u jedinici vremena prođe kroz jedinicu površine materijala. Ovaj parametar se često koristi za ocenjivanje performansi odevnih tekstilnih materijala i tehničkog tekstila kao što su tkanine za vazdušne jastuke, jedra i padobrane, i industrijski tekstilni filteri. U stručnoj praksi, koja ne uključuje obavezno naučna istraživanja, neophodno je da se sva testiranja tekstilnih materijala vrše prema normama propisanim važećim standardima. Propustljivost vazduha tekstilnih materijala najčešće se ispituje standardnim metodama ASTM D737 i ISO 9237. Vrlo često se dešava da se kvantifikovane vrednosti ispitivanog svojstva tekstilnog materijala razlikuju u zavisnosti od upotrebljenog uređaja, odnosno primenjene standardne metode. Zbog toga je u okviru ovog istraživanja izvršeno poređenje rezultata propustljivosti vazduha grupe DL pletenina, koji su dobijeni primenom dva različita uređaja i dve standardizovane (ASTM D737 i ISO 9237) metode. Poređenjem dve grupe rezultata propustljivosti vazduha DL pletenina uočene su razlike u vrednosti ovog parametra kod svih ispitivanih pletenina. Ipak, zapažen je isti trend u pogledu uočenih razlika u propustljivosti vazduha pletenina, što je potvrđeno visokom vrednošću koeficijenta korelacije (r=0,98)

Sposobnost upravljanja vlagom glatkih pletenina izrađenih od prirodnih i regenerisanih celuloznih vlakana

Moisture management is a complicated process which is known to be influenced by a variety of fabric characteristics such as fibre nature (hydrophilic or hydrophobic), porosity and thickness. There are different aspects of the moisture management properties of textile materials since water transport in textile materials can be in the form of liquid and vapour. The ability of textile materials to transfer water vapour allows the human body to keep thermal balance due to evaporation. With stronger physical activity of a person when the body produces a large amount of heat, the skin perspiration increases (in order to regulate the body temperature) and liquid sweat should be taken from the skin, otherwise it will worsen the sense of comfort. The aim of this research was to investigate the factors influencing moisture management properties of plain knitted fabrics at the three scale levels, i.e., microscopic (fibre type), mesoscopic (yarn geometry) and macroscopic (fabric porosity) levels. Plain knitted fabrics were produced from the two-assembled hemp, cotton and viscose yarns under controlled conditions so as to be comparable in basic construction characteristics, but varying in yarns geometry. Evaporative resistance test reflecting vapour transport and water distribution test reflecting liquid transport in the knitted fabrics were conducted. To determine the statistical importance of the results, analysis of variance (ANOVA) was applied. As a consequence of the geometry and deformation behaviour of the fibres used and spinning techniques applied, the yarns differed in both packing density and surface geometry, thus determining the pore distribution. Due to loose structure of the cotton yarn, the cotton knitted fabric was characterised by the lowest free open surface (macroporosity) exhibiting the lowest both water vapour and liquid permeability. Although having the highest macroporosity, the water vapour and liquid transport capability of the hemp knitted fabric was lower than that of the viscose knit. The best moisture management properties of the viscose knitted fabric were resulted from viscose affinity for water absorption and increased surface area of the viscose yarn. The results obtained proved that variations in any of the hierarchical structure levels can modify moisture transport ability of textile fabrics. Therefore, the moisture management properties of textile materials can be guided in a desired direction by the appropriate selection of fibres and careful design of yarn structure.Cilj ovog rada je bio karakterizacija glatkih pletenina u pogledu sposobnosti upravljanja vlagom (propuštanja vodene pare i znoja) uzimajući u obzir faktore na mikroskopskom (vlakna), mezoskopskom (pređa) i makroskopskom (pletenina) nivou. U tu svrhu su, polazeći od pređa izrađenih od prirodnih i regenerisanih celuloznih vlakana, u kontrolisanim uslovima proizvedene glatke DL pletenine koje su podvrgnute ispitivanju propustljivosti vodene pare i tečnosti. Dobijeni rezultati ukazali su na kompleksan uticaj hijerarhijske strukture tekstilnog materijala na njegovu sposobnost upravljanja tečnostima. Pokazalo se da pored distribucije pora u pleteninama, koja je u okviru eksperimentalnog materijala bila uslovljena deformacionim svojstvima vlakana i primenjenim tehnikama predenja, propustljivost vodene pare može biti modifikovana geometrijom površine pređe, dok morfologija vlakana može da modifikuje propustljivost tečnosti

Characterization of microporous PP/PE nonwoven mats surface modified by deposition of electrospun nanofibers

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

A universal transportation model for reverse osmosis systems

This paper presents a new transport model for reverse osmosis (RO) systems, which combines irreversible thermodynamics, together with solution-diffusion theory. The simplifications adopted by the classical theory for solution-diffusion mechanisms have been found to be quite lacking when it comes to predicting the separation of multicomponent mixtures. The presented model accounts for multicomponent computations through the application of thermodynamic property models, as a means to predict the various interactions amongst the species that are present in solution. The developed transport model is relatively easy to implement, and can be utilized alongside existing equipment and thermodynamic property models. The applicability of the model presented in this paper has been tested on three different case studies, including a case that investigates single component behavior and a case that investigates multicomponent behavior The proposed model shows very good agreement with experimental results

Synthesis of nife2o4 nanofibers by joint sol-gel and electrospinning technique

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 ( lt 13nm). Magnetic behavior of the obtained material at elevated temperatures was also scrutinized using thermomagnetic measurements (TM) up to 800 degrees C