Wyniki wyszukiwania - Biblioteka Nauki

1

Mechanical buckling of functionally graded polyethylene/clay nanocomposites columns based on the Engesser-Timoshenko beam theory

100%

Yas M. H. , Khorramabadi M. K.

Journal of Theoretical and Applied Mechanics

|

2018

|

tom Vol. 56 nr 3

701--712

EN

This paper deals with mechanical buckling of polyethylene/clay nanocomposite beams of functionally graded and uniformly distributed of nanoclay subjected to axial compressive load with simply supported conditions at both ends. The Young moduli of functionally graded and uniformly distributed nanocomposites are calculated using a genetic algorithm procedure and then compared with experimental results. The formulation is modiﬁed to include the eﬀect of nanoparticles weight fractions in the calculation of the Young modulus for uniform distribution. Also, it is modiﬁed to take into account the Young modulus as a function of the thickness coordinate. The displacement ﬁeld of the beam is assumed based on the Engesser-Timoshenko beam theory. Applying the Hamilton principle, governing equations are derived. The inﬂuence of nanoparticles on the buckling load of the beam is presented. To investigate the accuracy of the present analysis, a compression study with the experimental results is carried out.

2

Heterogeneous radiolysis of urea. Implications in astrobiology and prebiotic chemistry

100%

Abigail E. Cruz-Hernández, A. E. , Colin-Garcia M. , Heredia-Barbero A. , Negron-Mendoza A. , Ramos-Bernal S.

Open Chemistry

|

2015

|

tom 13

|

nr 1

EN

Urea is an organic molecule present in most living organisms. Historically, it was the first organic molecule synthesized in the laboratory. In prebiotic chemistry, urea readily forms in different laboratory simulations using different energy sources. Furthermore, the role of solid surfaces, particularly minerals, might have been crucial to increase the complexity of the organic matter which may have led to the subsequent emergence of life on Earth. In this work, the radiolysis of urea in presence of a clay is studied to determine to what extent the mineral surfaces influence the decomposition of organics. The results indicate that urea is relatively stable to ionizing radiation in aqueous solutions and up to 20 kGy no decomposition is observed. Moreover, the presence of sodium montmorillonite, by a mechanism until now unknown, affects the radiolytic behavior and urea remains in the heterogeneous solution without a change in concentration even at very high doses (140 kGy). These results indicate that solids could have protected some organics, like urea, from degradation enabling them to remain in the environment on the primitive Earth.

3

Catalytic Combustion of Trichloroethylene over Pd-Doped Ti-Pillared Montmorillonites

100%

Bahranowski K. , Gaweł A. , Janik R. , Komorek J. , Machej T. , Michalik A. , Serwicka E. , Włodarczyk W.

Polish Journal of Chemistry

|

2003

|

tom Vol. 77 / nr 5

675-682

EN

Palladium (0.8 wt.%) was introduced onto Ti-pillared montmorillonite samples by means of incipient wetness technique either before or after calcination of the pillared matrix. Combustion of trichloroethylene (TCE) has been chosen to test the catalytic properties of clay catalysts in deep oxidation of chlorinated volatile organics. The results were referred to the performance of a commercial catalyst. Both materials based on pillared clays were more active than the reference sample. The clay sample doped after calcination was better of the two and gave complete combustion of TCE at temperature by 100 K lower than the commercial catalyst. This material showed also the highest selectivity to HCl at maximum TCE conversion. Further improvement of the clay catalyst performance in terms of the HCl yield and suppression of chlorine evolution was achieved by addition of the methanol vapour to the reaction mixture. The results are discussed in terms of textural and acidic properties of the investigated catalysts.

4

Application of recycled natural aluminasilicate doped with vanadium for the decontamination of the air

100%

Marcewicz-Kuba A. , Olszewska D.

Polish Journal of Chemical Technology

|

2007

|

tom 9

|

nr 2

65-67

EN

This paper reports studies on the influence of vanadium concentration on the catalytic activity of DESONOX catalysts (in DESOX reaction) based on modified montmorillonite from Jelsovy Potok. The investigation of the influence on the physicochemical properties of the catalysts on their behaviour has also been studied.

5

Examining the surface of the polyamide nanocomposite using optical profilometry

100%

Majka M. , Majka T. M.

Journal of Education and Technical Sciences

|

2014

|

tom Vol. 1, nr 1

8-9

EN

In this paper the results of neat polyamide 6 (PA6), processed matrix and polyamide 6 reinforced with montmorillonite 3 wt% (PA6/MMT), surface examination are presented. Examination of surface of the samples was performed using optical profilometry, which allows to measure their physical properties in non-invasive method. Based on the analysis of the radiation intensity of the reflected light from the surface the Fourier Transform was performed, to allow the analysis of images obtained in the frequency domain.

6

Modyfikacja glinek smektycznych jako napełniaczy polimerowych

100%

Olewnik E. , Garman K. , Czerwiński W.

Przetwórstwo Tworzyw

|

2010

|

tom [R.] 16, nr 4

179-180

PL

Przeprowadzono modyfikacje właściwości powierzchniowych montmorylonitu (MMT) za pomocą następujących związków organicznych: karbazolu (KBL), 3,6-diamino-1H karbazolu (DAK), 3,6-diamino-9-butylo-1H karbazolu (DANBUK) oraz N-n-heptachinoliny (C7Ch) i n-heksadecylochinoliny (C16-Ch). Zarówno dla surowego jak i zmodyfikowanego montmorylonitu przeprowadzono badania XRD, TG oraz analizę elementarną. Modyfikacja miała na celu zmianę właściwości MMT z hydrofilowych na organofilowe w związku z zastosowaniem montmorylonitu jako napełniacza polimerowego dla polietylenu i polipropylenu.

7

Hybrydowe układy typu polimer hydrofilowy/montmorylonit

100%

Drzycimska A. , Spychaj T.

Polimery

|

2008

|

tom T. 53, nr 3

169-175

PL

Przedstawiono przegląd literatury dotyczącej hybrydowych układów typu polimer hydrofilowy (kationowy, anionowy lub niejonowy)/montmorylonit (MMT), sposobów ich otrzymywania, metod oceny oraz kierunków zastosowania. Synteza tego typu produktów pozwala na modyfikację właściwości użytkowych polimerów. Szczegółowo scharakteryzowano zawierające MMT materiały hybrydowe na podstawie poliakryloamidu (PAAm), kopolimerów akryloamidu, poliwinylopirolidonu (PVP), poli(kwasu akrylowego) (PAA), poli(tlenku etylenu) (PEO), oligomerów i polimerów glikolu etylenowego, a także polimeru pochodzenia naturalnego - skrobi.

EN

A literature review on hybrid systems consisted of hydrophilic polymer (cationic, anionic or nonionic one) and montmorillonite (MMT, Fig. 1 and 2) is presented. The methods of preparation, evaluation and applications directions are discussed. Preparation of such products let modify the functional properties of polymers. The hybrid systems based on polyacrylamide (PAAm) (Fig. 3-5), acrylamide copolymers, polyvinylpyrrolidone (PVP), poly(acrylic acid) (PAA) (Fig. 6), poly(ethylene oxide) (PEO), oligomers or polymers of ethylene glycol (Fig. 7) or polymer of natural origin - starch, containing montmorillonite were characterized in detail.

8

Study of flocculation performance and mechanism of ultrafine montmorillonite particles with NPAM

100%

Wang L. , Min F. , Chen J. , Wang T. , Zhou Z.

Physicochemical Problems of Mineral Processing

|

2022

|

tom Vol. 58, iss. 3

art. no. 147790

EN

Ultrafine montmorillonite particles are the main clay minerals in industrial wastewater. In order to explore the flocculation performance and mechanism of flocculant with montmorillonite, the effects of nonionic polyacrylamide (NPAM) dosage and molecular weight on flocculation effect were studied using a flocculation sedimentation experiment. The morphology of flocs was observed by metallographic microscope and scanning electron microscope, and the microscopic adsorption mechanism was studied utilizing density functional theory (DFT). The results show that the best reagent system for the montmorillonite sample is that the molecular weight of NPAM is 14 million and the added amount is 100 g/t. The floc size increases with rising NPAM dosage, forming a unique multi-level compact space network structure through polymer bridging. The adsorption energy of acrylamide on the Na-(001) surface of montmorillonite is -108.81 kJ/mol, which is significantly higher than -50.66 kJ/mol on the None-(001) surface. Hydrogen bonding is not the main reason for the adsorption of acrylamide on the montmorillonite surface. NPAM mainly causes the flocculation and sedimentation of montmorillonite through the processes of polymer bridging and electrostatic attraction. This study can provide a theoretical basis for the design and synthesis of new flocculants.

9

Montmorillonite modified by unsaturated compatibilizing agents and by ionizing radiation as a potential filler in polymeric composites

100%

Nowicki A. , Przybytniak G. , Starosta W. , Sartowska B.

Nukleonika

|

2010

|

tom Vol. 55, No. 3

351-357

EN

For last several years we have studied modifications of montmorillonite (MMT) with different agents and the structural changes resulting from the processes. The aim of present work was focused on the preparation of polymer composites from epoxy resin and dispersed phase modified chemically and subsequently activated by irradiation. The paper presents investigations concerning intercalation of MMT by the synthesized unsaturated organophilic agents (on the basis of quaternary ammonium salts). The process was studied by: wide-angle X-ray scattering (WAXS), Fourier- -transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA); additionally mechanical properties of the polymer composite as well as its microscopic structure were tested. It was found that unsaturated quaternary ammonium salts can intercalate between MMT layers. The possibility of radiation-induced compatibilization between modified MMT particles and polymeric matrix was also studied. It was confirmed by electron paramagnetic resonance (EPR) spectroscopy that in the synthesized salts stable radicals are formed during irradiation, however their influence on mechanical properties of the final composite is insignificant.

10

Wpływ interkalowanych montmorylonitów na właściwości elastomerów butadienowo-akrylonitrylowanych

100%

Zaborski M. , Liszewska A. , Bednarek B.

Przemysł Chemiczny

|

2003

|

tom T. 82, nr 8-9

981-984

11

Montmorillonite as a Polyurethane Foams Flame Retardant

100%

Ubowska A.

Archivum Combustionis

|

2010

|

tom Vol. 30 nr 4

459-462

EN

Polyurethane foams are used in many applications for example in automotive industry. They are attractive especially because of cushioning and physical properties and easy handling. The use of polyurethanes for car, train or railway seats is determined by their behaviour during fire conditions. To improve the safety of polyurethane foams usage, flame retardants are applied for their production. The most popular are polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE), reputed as possibly environmentally hazardous (possibility of carcinogenesis by accumulation in the human body). Car producers like Volvo or Scania have published “Grey and black chemical list” to limit and eventually phase out hazardous substances from products and production process. Among these substances are PBB and PBDE [1, 2]. To solve this problem research for new fire retardants for polyurethane is intensified. In recent years some research has focused on montmorillonite (MMT) based fire retardants. MMT is one of the 2:1 type phyllosilicate clays with exchangeable cations in the interlamellar galleries. Its use in polymeric matrix improve mechanical properties, gas barrier performance and thermal properties. Polymer clay nanocomposites have been used by Toyota for barrier and under-hood engine parts since the 1990s. Recent usage in the 2004 Hummer H2 and the Chevrolet Impala are noted [3]. The improvement of fire retardant and thermal stability can be achieved when modified clay is applied. The exchangeable cations can be replaced with phosphonium [4], onium ions [5] or other.

12

The Activity of SO2 Removal from Combustion Gases by the DESONOX Type Catalyst Supported on by the DESONOX Type Catalyst Supported on Montmorillonite and Zeolite

100%

Marcewicz-Kuba A. , Olszewska D.

Polish Journal of Chemistry

|

2008

|

tom Vol. 82, nr 1-2

43-47

EN

In this paper the authors compared the modified montmorillonite and synthetic zeolite used as supports of the DESONOX type catalyst with the standard catalyst based on MgO. The addition of DESONOX catalyst doped with vanadium ions to combusted hard coal (mass ratio coal to catalyst was 500:1) results in SO2 removal from exhaust gases within the range from 57% to 67% for catalysts based on modified montmorillonite. The DESONOX catalyst based on zeolite is better than those based on montmorillonite. A study of supports and catalysts texture shows that the active material with vanadium ions accumulates on the pores exit and decreased pores radius and size, as well as specific surface areas of obtainedmaterials. Prepared catalysts are better than the standardDESONOX catalyst.

13

Ocena zmian właściwości mechanicznych i strukturalnych recyklatów polimerowych napełnianych montmorylonitem (MMT)

89%

Czarnecka-Komorowska D. , Tomczyk T.

Czasopismo Techniczne. Mechanika

|

2006

|

tom R. 103, z. 6-M

135-138

PL

W artykule przedstawiono wyniki badań wpływu zawartości montmorylonitu (MMT) na właściwości mechaniczne i strukturalne mieszanin recyklatów polipropylenu stosowanych do produkcji opakowań. Właściwości mieszanin rPP/MMT charakteryzowano w próbie rozciągania, udarności i twardości. Morfologię mieszanin oceniano na podstawie powierzchni przełomów metodą SEM. W wyniku badań stwierdzono, że wraz z zawartością MMT wzrasta naprężenie zrywające i twardość, a obniża się wydłużenie przy zerwaniu.

EN

The paper presents the effect of the montmorillonite (MMT) content on the mechanical and structural properties of recycled polypropylene used for producing of plastic packaging. The properties of rPP/MMT blends were characterized by the tensile test, impact test and hardness. Morphology of fractured surface of blends was observed by SEM. The results showed that the addition of MMT to rPP increased tensile strength and hardness and decreased the elongation at break.

14

Thermoplastic elastomers containing 2D nanofillers: montmorillonite, graphene nanoplatelets and oxidized graphene platelets

88%

Paszkiewicz S. , Pawelec I. , Szymczyk A. , Rosłaniec Z.

Polish Journal of Chemical Technology

|

2015

|

tom Vol. 17, nr 4

74--81

EN

This paper presents a comparative study on which type of platelets nanofiller, organic or inorganic, will affect the properties of thermoplastic elastomer matrix in the stronger manner. Therefore, poly(trimethylene terephthalate-block-poly(tetramethylene oxide) copolymer (PTT-PTMO) based nanocomposites with 0.5 wt.% of clay (MMT), graphene nanoplatelets (GNP) and graphene oxide (GO) have been prepared by in situ polymerization. The structure of the nanocomposites was characterized by transmission electron microscopy (TEM) in order to present good dispersion without large aggregates. It was indicated that PTT-PTMO/GNP composite shows the highest crystallization temperature. Unlike the addition of GNP and GO, the introduction of MMT does not have great effect on the glass transition temperature of PTMO-rich soft phase. An addition of all three types of nanoplatelets in the nanocomposites caused the enhancement in tensile modulus and yield stress. Additionally, the cyclic tensile tests showed that prepared nanocomposites have values of permanent set slightly higher than neat PTT-PTMO.

15

Fracture of Aluminium Joints Bonded with Epoxy Adhesive Reinforced by MMT Nanoparticles

88%

Budzik M. , Pilawka R. , Imielińska K. , Jumel J. , Shanahan M. M.

Advances in Materials Science

|

2009

|

tom Vol. 9, nr 2(20)

4-11

EN

Crack propagation behavior was studied for aluminium/aluminum adhesive joints bonded with two epoxy adhesives: pure and reinforced with clay nanoparticles. The focus was also on the novel use of the constant displacement rate test to study adhesion/adhesives efficiency. The epoxy systems studied were: Epidian E6 produced from bisphenol A and epichlorohydrin, ("Organika -Sarzyna" Poland); pure or strengthened with montmorillonit nanoparticles (MMT). Crack growth rate was estimated for two displacement rates. The nanoparticle reinforced epoxy showed advantage over pure epoxy adhesive (Figs. 4,5). This effect was more pronounced at low deflection rates. The constant displacement rate test was found promising to study microstructural effects in adhesive joints.

16

Effect of organophilization and interlamellar silylation of montmorillonite on compatiblization of polymer composites

88%

Rahim M. A. , Ismail M. , Kandi A.

Advances in Science and Technology. Research Journal

|

2016

|

tom Vol. 10, nr 32

206--2016

EN

Sodium montmorillonite (Na-Mt) was modified by cetyltriemethylammoniumbromide (CTAB) through cation exchange technique followed by grafting with 3-aminopropyltriethoxysilane (APT). The effects of organophillic surface treatments of montmorillonite on compatibilization of natural rubber (NR) /acrylonitrile butadiene rubber (NBR) blends was investigated. Physico-mechanical properties of rubber nanocomposites compatibilized with organomodified montmorillonite revealed strong nanocomposite with high tensile properties, impact strength and good resistance to flex fatigue, abrasion and compression set. Dynamic mechanical thermal analysis (DMTA) revealed a marked increase in storage modulus (E’) and lesser damping characteristics of organically modified clay mineral polymer nanocomposites (CPN) due to intercalation of organophilic montmorillonite by rubber matrix. The morphology of the blends became homogeneous and smoother with the presence of exofoliated/intercalated organically modified montmorillonite. Organomodified layered silicate sheets of montmorillonite greatly enhanced barrier properties by creating tortuous path that retarded the progress of solvent molecules through rubber matrix.

17

Influence of montmorillonite hydration and delamination on coal flotation

88%

Zhang L. , Zhang M. , Liu Q. , Song S. , Tian Y. , Barvora J. B.

Physicochemical Problems of Mineral Processing

|

2022

|

tom Vol. 58, iss. 6

art. no. 153085

EN

In this study, the influence of montmorillonite (MT) hydration and delamination on coal flotation was investigated through flotation tests using coal-MT mixtures. MT particles were subjected to hydration at different time intervals. The Fuerstenau upgrading curve was plotted to evaluate the change in overall flotation selectivity. The zeta potential and particle size distribution were used to characterize the delamination behavior of MT in deionized water at natural pH level. Atomic force microscopy (AFM) (colloidal probe) was used to analyze the interaction force between coal and MT particles. It was found that smaller particles (individual silicate layers or thin packets of layers) with higher zeta potentials appeared gradually, and their volume proportion increased with increasing hydration time. AFM results showed that a monotonous repulsive force was detected consistently throughout the separation distance between coal and these emerging smaller MT particles. The decrease of these MT coating on coal surface was responsible for the higher flotation recovery and better selectivity. A jump-into-contact phenomenon was observed in coal and MT interaction when MT hydrated incompletely. It showed that heterocoagulation between coal and MT occurred and MT coating on the coal surface was responsible for the depression of flotation.

18

Role of structural modifications of montmorillonite, electrical properties effect, physical behavior of nanocomposite proton conducting membranes for direct methanol fuel cell applications

88%

Abidin K. S. , Kannan R. , Palani P. B. , Rajashabala S.

Materials Science Poland

|

2017

|

tom Vol. 35, No. 4

707--716

EN

Proton exchange membranes have been synthesized from polyimide (PI) doped with different contents of montmorillonite (MMT) which was obtained by solution casting technique. The enhancement of conductivity was achieved through modification with the MMT. Prepared membranes were systematically characterized in terms of ion exchange capacity, water uptake, methanol uptake, swelling behavior and proton conductivity. Fourier transform infrared spectroscopy and X-ray diffraction measurements were used to confirm the structures of the PI/MMT composite electrolyte membranes. SEM surface morphological images of the composite membranes showed that the MMT nanoclay particles were dispersed uniformly within the membrane what was also reflected in XRD results which indicated a good compatibility of MMT particles with the polymer complex. The TGA spectra showed that the thermal stability of the membrane was reduced by adding MMT into the polymer network. The prepared membrane with 10 wt.% of modified MMT exhibited the highest proton conductivity value of 7.06 × 10-2 S·cm-1 at 70 °C. These results imply the potential application of the PI/MMT composite membranes as improved PEMs for DMFC applications.

19

Application of Thermoporometry Based on Convolutive DSC to Investigation of Mesoporosity in Cohesive Soils

88%

Kozłowski T. , Babiarz I. , Grobelska E.

Archives of Hydro-Engineering and Environmental Mechanics

|

2010

|

tom Vol. 57, nr 3-4

199-218

EN

In the method of thermoporometry, the characterization of pore space is done by analysis of thermal effects associated with freezing and melting of a liquid in the pores of the material under investigation. Thermoporometry seems particularly well suited to studies of wet porous samples in cases where the process of drying itself is able to destroy the original microstructure, as is the cohesive soils containing montmorillonite. In the paper, a variant of thermoporometry is given in which the blurred calorimetric peak is processed by use of a stochastic-convolutive analysis. As a result, a "sharp" thermogram of real thermal effects is obtained which can be easily transformed into a pore distribution curve. The preliminary results, obtained for samples of three monoionic montmorillonites at different water contents, indicate a greater resolution, sensitivity and precision than the classical thermoporometry using an unprocessed DSC signal. Phenomena corresponding to swelling have been detected in two individual regions on the differential pore distribution curves. The first is a dense spectrum for pores less than 15 nm. The second is a single peak for pores greater than 15 nm. Between the two regions the distribution decays to zero. Apparently, the point of the single peak maximum depends on the total water content, shifting rightward with increasing w. For the region below 20 nm, a strong effect of the kind of exchangeable cation can be observed. The results suggest swelling in the form with bivalent cations (Ca-montmorillonite) and contraction in the form with monovalent cations (Na- and K-montmorillonite).

20

Adsorption of water vapour on montmorillonite: grant canonical ensemble Monte Carlo simulations

88%

Delville A. , Sokolowski S. , Kozak E. , Sokolowska Z.

International Agrophysics

|

1995

|

tom 09

|

nr 1