Exfoliation

A polymerizable cationic surfactant, vinylbenzyldimethyldodecylammonium chloride (VDAC) was synthesized for functionalization of montmorillonite (MMT) and preparation of exfoliated polystyrene-clay nanocomposites. Organophilic MMT was prepared by cationic exchange between inorganic ions of MMT and ammonium cations of VDAC in an aqueous medium. Dispersions of intercalated clay (VDAC-MMT) in styrene monomer formed gels. Shear thinning behavior of the gels was observed via rheological measurements. Polystyrene-clay nanocomposites were prepared by free radical polymerization of styrene containing dispersed organophilic MMT. Exfoliation of MMT in polystyrene matrix was achieved as revealed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The exfoliated nanocomposites have higher dynamic modulus and higher decomposition temperature than pure polystyrene. ᭧

Layered silicate clays are natural crystallites and are well recognized for their structures and industrial applications, but there are very few reports on their structural confinement properties and on the mechanisms that underlie their polymer interactions. In this review, we summarize the recent progress on clay modification via conventional ion exchange reactions, sol-gel linking, atom transfer radical polymerization, and polymer intercalation. The organic interaction of ionic clays involves different noncovalent bonding forces, such as amido acid five-membered ring chelation, carboxylic acid chelation, intermolecular hydrogen bonding, and double-layer hydrophobic alignment in a layered clay confinement. Controlling the organic species, their amounts and their self-assembled conformation in a clay confinement could lead to the tailoring of the silicate platelet interlayer distance and of their organophilic properties.

This paper is concerned with restrictions on Left-Branch Extraction (LBE) in
Bulgarian and Macedonian, the only two Slavic languages with articles. The
data indicate that the availability of LBE is related to the number of modiers,
and thus require a revision of the generalisation that all languages with articles
disallow LBE. Following Martinović (2019), Calabrese & Pescarini (2014), a
solution based on the order of operations is proposed, connecting the availability
of LBE to the idea that projections can be removed via syntactic operations
such as Exfoliation (Pesetsky 2019). The application of Exfoliation depends
on the relative timing of article placement, which in turn is performed via a (revised)
post-syntactic operation of Generalised Lowering (Embick & Noyer 2001).
Exfoliation and subsequently LBE are fed by an early application of Lowering,
assumed to be able to interleave narrow syntax (Martinović 2019), but if applied
late, Lowering counter-feeds these two operations.

The effect of high energy ball milling under different conditions on the structure of Na + -montmorillonite (Na-MMT), and the organo-montmorillonite (Cloisite 30B) was investigated. Ball milling increased the structural disorder: peeling off of layers from the particles was observed, followed by the exfoliation of the particles, indicated by the disappearance of the (001) reflection. X-ray diffraction and infrared spectra revealed that the exfoliated layers did not show deteriorated structures. The presence of the alkylammonium ions seemed to stabilize the structure by reducing exfoliation.

Zeolites-microporous crystalline aluminosilicates-are widely used in petrochemistry and fine-chemical synthesis 1-3 because strong acid sites within their uniform micropores enable size-and shape-selective catalysis. But the very presence of the micropores, with aperture diameters below 1 nm, often goes hand-in-hand with diffusion limitations 3-5 that adversely affect catalytic activity. The problem can be overcome by reducing the thickness of the zeolite crystals, which reduces diffusion path lengths and thus improves molecular diffusion 4,5 . This has been realized by synthesizing zeolite nanocrystals 6 , by exfoliating layered zeolites 7-9 , and by introducing mesopores in the microporous material through templating strategies 10-17 or demetallation processes . But except for the exfoliation, none of these strategies has produced 'ultrathin' zeolites with thicknesses below 5 nm. Here we show that appropriately designed bifunctional surfactants can direct the formation of zeolite structures on the mesoporous and microporous length scales simultaneously and thus yield MFI (ZSM-5, one of the most important catalysts in the petrochemical industry) zeolite nanosheets that are only 2 nm thick, which corresponds to the b-axis dimension of a single MFI unit cell. The large number of acid sites on the external surface of these zeolites renders them highly active for the catalytic conversion of large organic molecules, and the reduced crystal thickness facilitates diffusion and thereby dramatically suppresses catalyst deactivation through coke deposition during methanol-togasoline conversion. We expect that our synthesis approach could be applied to other zeolites to improve their performance in a range of important catalytic applications.

Inland notches, are elongated concave-shape indentations that develop on the carbonate rocky cliffs of mountainous zones, down to the desert fringe. These rock shelters form as a result of the interaction between specific petrologic characteristics and climatic controls, emphasizing the importance of environment upon rock decay. Inland notches are shaped due to slight differences (1–15%) in the porosity of the visor and cavity bed: the cavity bed is more porous, so more likely to erode by exfoliation and dissolution. Thus, the cavity bed retreats at a faster rate compared to the slower subaerial dissolution of the visor bed, until a critical point is reached where the visor collapses. In Israel, inland notches inhabit the same lithostratigraphic units as do large caves. The vast majority (71%) of inland notches are formed in hard, dense, and crystalline limestone deposited throughout the Turonian age. Another 27% are cut into the dolomitic sequence of the upper Albian and lower Cenomanian. The rest (2%) are dispersed in the various formations of the Cenomanian and Eocene eras. Notches are most common in semi-arid and in Mediterranean climates but mainly in areas with annual rainfall of between 400 mm and 850 mm. In more humid areas (> 900 mm/yr) notches are negligible or completely absent, due to the rapid rate of chemical dissolution of carbonate rocks. In the desert fringe (200–300 mm/yr), mechanical decay is accelerated and notches exhibit disintegration processes, visor collapse, and rock falls. In the desert area (< 200 mm/yr), salt decay replaces the chemical decay characteristic of inland notches, encouraging tafoni formation. In addition, notches form through fluvial activity or on account of greater petrophysical differences between consecutive beds; i.e. elongated cavities may form in soft rocks, shaded by harder visors or crusts.

The present work consists in the study of the modification of a nano-layered vermiculite by thermal treatment up to 900 °C. Changes in the structure and texture after thermal treatment were used for evaluation of dehydration properties of the studied material. The dehydration properties of the clay are strongly affected by the crystal structure.The Differential Thermal Analysis (DTA) allows the determination

Desilication of the medium-pore ferrierite zeolite in sodium hydroxide solutions was conducted to modify the porous structure and to create structural defects, resulting in enhanced accessibility and ultimately improved catalytic performance. Commercial H-ferrierite (Si/Al = 29) with the characteristic plate-like morphology was used as starting material. The attack by NaOH induces deaggregation, exfoliation, fracture, and ultimately perforation of the ferrierite crystals, resulting in mesoporosity of combined inter-and intracrystalline nature. The parent and treated samples were characterized by ICP-OES, XRD, N 2 adsorption, SEM, TEM, 27 Al and 29 Si MAS-NMR, FTIR, and NH 3 -TPD. Optimization of the treatment conditions (NaOH concentration, temperature, and time) is required to introduce substantial mesoporosity without significantly altering the micropore structure due to excessive Si leaching. Compared to other frameworks (e.g. MFI, MTW, MOR, and BEA), FER requires harsher conditions to extract silicon leading to mesoporosity. Under optimal conditions, the mesopore surface area of the NaOH-treated ferrierite increased by a factor of 3-4 with respect to the parent zeolite, while mostly preserving the native crystallinity and acidity. The ability of NaOH to induce porosity changes in FER largely exceeds conventional dealumination post-treatments. The benefit of the introduced porosity was demonstrated in the catalytic pyrolysis of low-density polyethylene.

Purpose of  Study--Herein we report the preparation of poly(N-vinyl carbazole)  (PVK)  and graphene oxide  (GO)  or nanocomposite was carried out by solution mixing process with the aid of sonication. Solutions of the GO  with the PVK were prepared using mixed solvents aided by sonication which resulted in exfoliation and disaggregation of the  GO  into the PVK polymer matrix.
Methodology--In this work,  the  PVK/GO  was prepared from exfoliated graphite nanoplatelets using a solution mixing process with the aid of sonication in a  suitable solvent like  N-cyclohexyl-2-pyrrolidone  (CHP).    The as-prepared nanocomposites were characterized using XRD, DSC, FTIR-KBr, UV-Vis and EIS analysis.
Main Findings--The preparation of PVK/GOnanocomposites was carried out by solution mixing process with the aid of sonication.  Using this method in dispersing the GOboth exfoliation of the GOinto the PVK polymer matrix was attained.  Nanocomposite solution comprising  GOwrapped within  PVK  polymer matrix was characterized using TGA,  XRD,  and EIS  analysis. FTIR-ATR  spectroscopy and  XRD  invoked the wrapping of  GOouter surfaces by  PVK.    The thermal properties of  PVK/GO nanocomposites were analyzed using  TGA.    Correlation of impedance data and  XRD  provided a structural rationale for PVK/nanocomposites.
Application of  Study--The  PVK/GO  nanocomposites can be applied to various applications such as precursor polymer for hole-transporting materials and for electronanopatterning.
Limitations--The study is limited to the characterization of the prepared  GO  and  PVK/GO  nanocomposites.  Possible applications of the composites were not part of the study.
The originality of the Study--The findings of the study show that it is possible to prepare graphene/PVK nanocomposites using a solution mixing process

We have developed a new process for the synthesis of a layered niobium sulfide that involves heating K 4 Nb 6 O 17 Á 3H 2 O with a H 2 S/N 2 gas mixture. It was confirmed that heating the starting layered oxide at 750 1C for 10 h under the gas flow yielded a highly crystalline, single-phase K 0.34 (H 2 O) 0.7 NbS 2 . The layered sulfide slabs had a large plate-like shape. Potassium ions in the interlayer of K 0.34 (H 2 O) 0.7 NbS 2 could be exchanged with protons by stirring in 2 M H 2 SO 4 . It was found that the proton in the proton-exchanged form can be easily exchanged with other cations. The proton-exchanged form was exfoliated into NbS 2 nanosheets by ultrasonication in water. According to the atomic force microscopy (AFM) images, NbS 2 nanosheets had a thickness of around 4 Å , which roughly corresponded to the thickness of a single NbS 2 host layer. NbS 2 nanosheets could be restacked with the intercalation of Eu 3+ or tetrabutylammonium ions by an electrostatic self-assembly deposition (ESD) technique. r

A polymerizable cationic surfactant, vinylbenzyldimethyldodecylammonium chloride (VDAC) was synthesized for functionalization of montmorillonite (MMT) and preparation of exfoliated polystyrene-clay nanocomposites. Organophilic MMT was prepared by cationic exchange between inorganic ions of MMT and ammonium cations of VDAC in an aqueous medium. Dispersions of intercalated clay (VDAC-MMT) in styrene monomer formed gels. Shear thinning behavior of the gels was observed via rheological measurements. Polystyrene-clay nanocomposites were prepared by free radical polymerization of styrene containing dispersed organophilic MMT. Exfoliation of MMT in polystyrene matrix was achieved as revealed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The exfoliated nanocomposites have higher dynamic modulus and higher decomposition temperature than pure polystyrene. ᭧

A unique two-step modified Hummers method is developed to unzip and exfoliate multiwalled carbon
nanotubes (MWCNTs) into low-defect graphene oxide nanoribbons (GONRs). From the X-ray diffraction
(XRD), Raman spectroscopic (RS), X-ray photoelectron spectroscopic (XPS), Fourier transform infrared
spectroscopic (FTIR), and transmission electron microscopic (TEM) results, a mechanism involving
multilayer-unzipping followed with rapid local peeing-off (i.e., exfoliation) is proposed for this two-step
Hummers procedure which provides a guide for obtaining high-quality GONRs. In the two-step
procedure, both multilayer-unzipping of MWCNTs and oxidative exfoliation of multilayer GONRs are
accelerated by a freshly prepared, concentrated KMnO4 medium. This action reduces the random
damage on the basal plane of resultant GONRs, which is commonly found in the ineffective, timewasting,
oxidant-consuming, one-step strategy. Consequently, low-defect GONRs can be efficiently
fabricated in this two-step process.

Dust engenders a fear of the unseen, an anxiety and horror at the dissolution of matter to a minute scale; it is amorphous, all pervading, and knows no boundaries. Through the inevitable progress of time the body is transformed and reduced to
dust as the outer layers are shed as dander. In its smallest form the body is grotesque and undelineated. Our dead return to dust but so too do the living. The skins and cells of our moving, breathing bodies disperse into the world, mingling
with foreign matter and waste as we pass through space. Dust forms stagnant veils coating objects of disuse, gathering in corners and floating above our beds. It is an
unsettling and permanent presence, marginal and transitional, without site or bounds.

This paper explores bodies that are decentralised and in a state of dusty disintegration. It addresses the horror of the body in a state of dissipation by asking: where and when does the body begin? Where may it end? And how might the body's transgressed boundaries offer up possibilities for designing wearable artefacts?

Achievement of exfoliated structure of polymer/ Clay nanocomposites is of particular interest for the improvement of mechanical properties. In this work, the morphology and mechanical properties of epoxy/ clay nanocomposites has been investigated. Diglycidyl ether of bisphenol A (DGEBA) epoxy resin (EPON828) and Jeffamine D400 curing agent was used. To obtain perfect dispersion, nanoclay (Cloisite 30B) was sonicated in acetone. The mixture was then mixed with polymer. Afterwards, the curing process was performed by addition of curing agent and degassing. Disappearing of peaks in X-Ray diffraction patterns of nanocomposites containing less than 5wt% nanoclay, is a good evidence of perfect dispersion of layered silicates in matrix, i.e. formation of exfoliated morphology. Based on tensile test results, it is deduced that as the amount of nanoclay increases, the elastic modulus and elongation at break of the nanocomposites containing 1wt% and 5wt% nanoclay increases by 12% and 31%, respectively. Therefore, obtaining perfect dispersion of layered silicates in epoxy matrix and exfoliated morphology, results in better mechanical properties of the nanocomposites.

In recent times, the materials properties of graphene have generated ever-increasing interest across multiple scientifi c disciplines including physics, material science and chemistry. The quantity and quality of graphene produced directly impacts the performance and development of applications related to organic fi eld-effect transistors (OFETs), conductive materials, [ 2b , 5 ] and photovoltaics, not forgetting biological applications. Generally, the techniques used to prepare graphene are based on either physical processes, chemical methodologies [ 3a , 9 ] or a blend of the two. Although physical methods are able to produce high-quality graphene consistently, the amount of processable graphene produced is always limited, as well as being quite costly. Conversely, although chemical oxidation of graphite to graphene oxide (GO), followed by reduction, results in reduced graphene oxide (RGO) in large quantities, this method generates defect-laden RGO to the extent that the resultant graphene is generally of lower quality than that produced by physical methods. Despite the fact that there are some reports relating to the use of wet chemistry to exfoliate graphene from graphite, the exfoliation of graphite to graphene employing noncovalent ππ interactions with π -conjugated molecules in water is relatively unexplored. Herein, we describe the preparation of graphene by direct exfoliation of graphite through the exploitation of ππ interactions between the N,N ′ -dimethyl-2,9-diazaperopyrenium dication ( MP 2 + ) and graphene in aqueous media.

Layered double hydroxides (LDH) are a class of readily synthesizable layered crystals that can be used as an alternative to the commonly used silicate crystals for the preparation of polymeric nanocomposites. In this work layered double hydroxide/polyamide 6 nanocomposites (LDH/PA6) were prepared from organo-modified LDH by melt processing. The anionic exchange capacity of LDH was varied in order to investigate its influence on the degree of exfoliation. LDH were dispersed by a twin screw micro-extruder at a variety of processing conditions. The nanocomposites were characterized by wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS), transmission electron microscopy, dynamic scanning calorimetry, and thermogravimetric analysis. It was found that exfoliated nanocomposites were successfully prepared by melt processing with a low exchange capacity LDH, whereas residue tactoids were observed with a high exchange capacity LDH. Shear, together with the exchange capacity, seems to be the key factor for the delamination in LDH/PA6. No major change in the crystalline phase or in the rate of crystallization was observed in the nanocomposite as compared to the neat polymer. A reduction in the onset of thermal decomposition temperature was observed in PA6/LDH compared to neat PA6, likely due to a nucleophilic attack mechanism. The properties of this nanocomposite system are discussed with connections to the current understanding within the broader nanocomposite field. q

Zeolites-microporous crystalline aluminosilicates-are widely used in petrochemistry and fine-chemical synthesis 1-3 because strong acid sites within their uniform micropores enable size-and shape-selective catalysis. But the very presence of the micropores, with aperture diameters below 1 nm, often goes hand-in-hand with diffusion limitations 3-5 that adversely affect catalytic activity. The problem can be overcome by reducing the thickness of the zeolite crystals, which reduces diffusion path lengths and thus improves molecular diffusion 4,5 . This has been realized by synthesizing zeolite nanocrystals 6 , by exfoliating layered zeolites 7-9 , and by introducing mesopores in the microporous material through templating strategies 10-17 or demetallation processes . But except for the exfoliation, none of these strategies has produced 'ultrathin' zeolites with thicknesses below 5 nm. Here we show that appropriately designed bifunctional surfactants can direct the formation of zeolite structures on the mesoporous and microporous length scales simultaneously and thus yield MFI (ZSM-5, one of the most important catalysts in the petrochemical industry) zeolite nanosheets that are only 2 nm thick, which corresponds to the b-axis dimension of a single MFI unit cell. The large number of acid sites on the external surface of these zeolites renders them highly active for the catalytic conversion of large organic molecules, and the reduced crystal thickness facilitates diffusion and thereby dramatically suppresses catalyst deactivation through coke deposition during methanol-togasoline conversion. We expect that our synthesis approach could be applied to other zeolites to improve their performance in a range of important catalytic applications.

The catalytically important vanadyl hydrogen phosphate hemihydrate, VOHPO 4 AE 0.5H 2 O phase with strong interlayer bonding has been exfoliated for the first time in DMF-water mixture and the exfoliated hemihydrate phase has been reorganized into a novel mesostructured lamellar VPO phase having the same V-P-O connectivity as in VOHPO 4 AE 0.5H 2 O, using octadecyl amine as the structure directing template.

Polyacrylonitrile (PAN)/single wall carbon nanotubes (SWNT) fibers were gel spun at 0, 0.5, and 1 wt% SWNT content to a draw ratio of 51. Structure, morphology, and mechanical and dynamic mechanical properties of these fibers have been studied. PAN/SWNT composite exhibited much higher electron beam radiation resistance than PAN. As a result, PAN lattice images could be easily observed in the composite fiber by high resolution transmission electron microscopy. The PAN/SWNT composite fiber also exhibited higher solvent resistance than the control PAN fiber. UV-vis spectroscopy of highly drawn fiber exhibited van Hove transitions, suggesting SWNT exfoliation upon drawing. SWNT exfoliation was also confirmed by high resolution transmission electron microscopy (HRTEM). At 1 wt% SWNT loading, fiber storage modulus (at 1 Hz) increased by 13.9, 6.6, and 0.2 GPa at K75, 25, and 150 8C, respectively. This suggests that the load transfer ability and hence interfacial strength is increasing with decreasing temperature, even below the polymer's g transition temperature.

Chlorinated polyethylene (CPE)/organophilic-montmorillonite (Cloisite Ò 30B (CL30B)) nanocomposites have been prepared by melt intercalation using (poly(e-caprolactone), (PCL)) as CPE/clay compatibilizer. Actually, a high clay content masterbatch-based on PCL was first produced and then dispersed by melt blending within CPE. CPE/CL30B nanocomposites was also prepared by direct blending of CPE with CL30B for sake of comparison. All the composites were characterized by wide-angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The thermal stability of the nanocomposites was analyzed by thermogravimetric analysis (TGA) while the mechanical properties were assessed by tensile testing. When using low molecular mass PCL chains as compatibilizer, the nanocomposites displayed a rather intercalated structure but their ultimate properties remained unchanged whereas with high molecular weight PCL chains, clay delamination was favoured and led to an increase of both thermal and mechanical properties of the resulting nanocomposites.

Medium chain length polyhydroxyalkanoates (mcl-PHA) have been produced by fed-batch cultivation of Pseudomonas oleovorans. Using octanoic acid as the sole carbon substrate, a copolymer of 3-hydroxyoctanoate and 3-hydroxyhexanoate monomer units was accumulated up to 38 wt. % of cell mass. Mcl-PHA based nanocomposites have then been prepared using Cloisite 15A as nanofiller and characterized. Wide angle X-ray diffraction and rheological analysis of the nanocomposites highlighted their morphologies, which can be considered as well-intercalated structures. The thermal characteristics of mcl-PHA are not significantly affected by the nanofiller incorporation. On the contrary, the storage moduli of nanocomposites are greatly enhanced with increasing clay fraction due to the degree of dispersion of the nanoplatelets in the polymer matrix.

Many applications of carbon nanotubes require the exfoliation of the nanotubes to give individual tubes in the liquid phase. This requires the dispersion, exfoliation and stabilisation of nanotubes in a variety of liquids. In this paper we review recent work in this area, focusing on results from the author's group. We begin by reviewing stabilisation mechanisms before exploring research into the exfoliation of nanotubes in solvents, by using surfactants or biomolecules and by covalent attachment of molecules. The concentration dependence of the degree of exfoliation in each case will be highlighted. In addition we will discuss research into the dispersion mechanism for each dispersant type. Most importantly we have compared dispersion quality metrics for all dispersants. From this analysis, we conclude that functionalised nanotubes can be exfoliated to the greatest degree. Finally, we review the extension of this work to the liquid phase exfoliation of graphite to give graphene.

Damage to buildings such as crack and exfoliation requires continuous maintenance because the risk of safety accidents increases. However, existing detection method for the damage is visual inspection method, there is a limitation. Recently, unmanned aerial vehicle with high mobility and versatility equipped with various sensors is attracting attention in safety inspection. This study detected and quantified the crack and exfoliation appearing on the exterior of a building using an unmanned aerial vehicle. As a result of the study, 4 exfoliations and 8 cracks were detected. And the detected cracks were quantified using image processing techniques. This study is expected to be used as a basic study when developing building safety inspection techniques using an unmanned aerial vehicle.

The dispersion of clay in a polymer matrix is influenced by two factors: the choice of organic treatment for the clay and the processing or mixing method. Maximum benefits are achieved when the platelets are well dispersed or exfoliated. Exfoliated nanocomposites are formed when the individual clay layers break off the agglomerated particles or tactoids and are either randomly dispersed in the polymer (a disordered nanocomposite) or left in an ordered array. It is suggested that size reduction of clay particles and platelet delamination occur by erosion or surface peeling. A model based on the classical theories of interparticle interactions was formulated for the exfoliation of the clay platelets in a polymer matrix. The model involves the estimation of the binding energy and the adhesive force between the platelets in a clay particle, which indicate the forces required for breaking apart or delamination of clay particles. Then, the shear force required for breakup or delamination of the tactoids is estimated and compared to the hydrodynamic shear forces available during processing. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers

Exfoliation (pseudoexfoliation; PEX) syndrome is the single most common identifiable cause of open-angle glaucoma, however, very few investigators are engaged in basic research on this disease. To stimulate the field, the First International Think Tank on Exfoliation Syndrome was held in New York in July 1999, comprising clinicians and scientists. This report is a summary of the proceedings of this meeting.

Layered double hydroxides (LDH) are a class of readily synthesizable layered crystals that can be used as an alternative to the commonly used silicate crystals for the preparation of polymeric nanocomposites. In this work layered double hydroxide/polyamide 6 nanocomposites (LDH/PA6) were prepared from organo-modified LDH by melt processing. The anionic exchange capacity of LDH was varied in order to investigate its influence on the degree of exfoliation. LDH were dispersed by a twin screw micro-extruder at a variety of processing conditions. The nanocomposites were characterized by wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS), transmission electron microscopy, dynamic scanning calorimetry, and thermogravimetric analysis. It was found that exfoliated nanocomposites were successfully prepared by melt processing with a low exchange capacity LDH, whereas residue tactoids were observed with a high exchange capacity LDH. Shear, together with the exchange capacity, seems to be the key factor for the delamination in LDH/PA6. No major change in the crystalline phase or in the rate of crystallization was observed in the nanocomposite as compared to the neat polymer. A reduction in the onset of thermal decomposition temperature was observed in PA6/LDH compared to neat PA6, likely due to a nucleophilic attack mechanism. The properties of this nanocomposite system are discussed with connections to the current understanding within the broader nanocomposite field.

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A micromechanical model for prediction of the elastic modulus of polymer/layered silicate nanocomposites was developed based on the conventional Halpin-Tsai model. The model considers near realistic intercalated and exfoliated structures of nanocomposites. The dependence of exfoliation ratio (the ratio of exfoliated filler content to the total filler content) on the filler concentration has been studied from different viewpoints and an exfoliation ratio function has been proposed. The predictions of the proposed model with variable exfoliation ratio functions were compared with the predictions of the same model with constant exfoliation ratio and the predictions of the Halpin-Tsai model using experimentally obtained results. The results of the proposed model with variable exfoliation ratio functions are in very good agreement with experimental data, particularly taking their nonlinearities into account.

Herein, we report the efficiency of mechanochemical method as a simple, green and environmental approach to synthesis of exfoliated graphite (EG) consisting of multi and few layers of graphene. The layers of graphite expand under mild conditions using citric acid as a cheap and non-toxic intercalation and along with potassium permanganate as oxidation lead to exfoliation of graphite at room temperature. Measured conductivity of EG was 120 S/cm. Although EG has high conductivity, mixing it with zinc oxide (ZnO) and polyethylene shows great nonlinear properties. Results indicate that these combinations could be used as a varistor to protect electronic circuits. In addition, experimental results suggest that by increasing EG content in the mixture, breakdown voltage and nonlinear coefficient are both decreased from 360 to 40 V and 11.25 to 5.22 respectively. Finally, it was found that heat treatment on ZnO led nonlinear coefficient to decrease, the sample sintered at a lower temperature showing the highest nonlinearity.

Siapa sih yang gak mau punya kulit halus, bersih, glowing, dan tidak kusam? Apalagi sekarang udah 2022, biasanya kaum perempuan setiap akhir tahun selalu punya goals yang pengen dicapai, salah satunya kulit muka yang halus dan glowing. Nah pas banget, kali ini

Conventional processes for the manufacture of exfoliated natural vermiculite employ temperatures exceeding 800 °C and the onset temperature is above 450 °C. In many applications, notably fire retardants, it is desirable that exfoliation of vermiculite should occur at temperatures in the range of 200 °C to 350 °C. For this purpose, South African Palabora vermiculite was modified by ion exchange with ammonium and selected alkali metal and alkaline earth metal ions. These experiments were performed at room temperature using an orbital shaker for 15 days. Another set of experiments was performed by immersing vermiculite in saturated sodium chloride solution for periods up to six months. At the end of every month, sodium-exchanged vermiculite samples were taken for analysis. The thermal expansion and degradation of modified vermiculites were studied using thermo-mechanical analysis (TMA) and thermogravimetric analysis (TGA) respectively. Interlayer composition was studied using cation ex...

&amp;amp;amp;amp;amp;quot;In &amp;amp;amp;amp;amp;#x27;Pagan and Christian Creeds&amp;amp;amp;amp;amp;#x27; Edward Carpenter outlined his theory of the evolution of consciousness. The three ‘great stages’ were simple consciousness, self consciousness and: &amp;amp;amp;amp;amp;#x27;A third stage of consciousness which has not as yet been effectively named, but whose indications and precursive signs we here and there perceive in the rites and prophecies and mysteries of the early religions, and in the poetry and art and literature generally of the later civilisations.&amp;amp;amp;amp;amp;#x27; In this paper I will take Carpenter’s notion of ‘cosmic’ consciousness as my starting point, and explore the role of the ‘precursive sign’ both in Carpenter’s reading of Whitman’s &amp;amp;amp;amp;amp;#x27;Leaves of Grass&amp;amp;amp;amp;amp;#x27; and in his own Whitmanesque prose-poem &amp;amp;amp;amp;amp;#x27;Towards Democracy&amp;amp;amp;amp;amp;#x27;. In the above quotation, Carpenter aligns the arts with ancient pagan traditions, and traces the thread of spiritual consciousness from the religious through to the artistic sphere. For Carpenter, artistic works had become more effective conduits of spiritual ‘truth’ than religion as it was manifest in the nineteenth century. I will discuss the implications of this shift; specifically, the treatment of the poet as prophet and the reading of the poem as sacred text. This resonates through Carpenter’s approach to Whitman’s work, and through the construction of his own text in which he places himself in the vatic poetic line by recalling and adapting the thematic concerns, diction and stylistic properties of &amp;amp;amp;amp;amp;#x27;Leaves of Grass&amp;amp;amp;amp;amp;#x27;. &amp;amp;amp;amp;amp;quot;

BACKGROUND: Both exfoliated and toughened polypropylene-blend-montmorillonite (PP/MMT) nanocomposites were prepared by melt extrusion in a twin-screw extruder. Special attention was paid to the enhancement of clay exfoliation and toughness properties of PP by the introduction of a rubber in the form of compatibilizer toughener: ethylene propylene diene-based rubber grafted with maleic anhydride (EPDM-g-MA). RESULTS: The resultant nanocomposites were characterized using X-ray diffraction, atomic force microscopy, scanning electron microscopy, thermogravimetric analysis, dynamic mechanical analysis and Izod impact testing methods. It was found that the desired exfoliated nanocomposite structure could be achieved for all compatibilizer to organoclay ratios as well as clay loadings. Moreover, a mechanism involving a decreased size of rubber domains surrounded with nanolayers as well as exfoliation of the nanolayers in the PP matrix was found to be responsible for a dramatic increase in impact resistance of the nanocomposites. CONCLUSION: Improved thermal and dynamic mechanical properties of the resultant nanocomposites promise to open the way for highly toughened super PPs via nanocomposite assemblies even with very low degrees of loading.

The microcrystalline flaked graphites SFG6 and SFG44 were evaluated with regard to their compatibility with propylene carbonate (PC) by in situ Raman microscopy and postmortem scanning electron microscopy (SEM) study. PC is employed as electrolyte component in lithium-ion batteries. However, when used with certain types of graphitic materials, exfoliation occurs. To compare the effects of exfoliation, the first lithium insertion properties of these graphitic materials were measured with in situ Raman microscopy. Lithium half-cells containing either 1 M LiClO 4 1:1 (w/w) ethylene carbonate (EC):dimethyl carbonate (DMC) or 1:1 (w/w) EC:PC were investigated. The commencement of the exfoliation process was detected in SFG44 EC:PC by the appearance of a shoulder band at 1597 cm −1 on the G-band (1584 cm −1 ) below 0.9 V versus Li/Li + . The band (assigned as the exfoliation or E-band) at higher wavenumbers (1597 cm −1 ) corresponded to solvated lithium ions intercalated into graphite. The in situ Raman spectra of SFG6 in EC:DMC or EC:PC and SFG44 in EC:DMC did not show the E-band and instead displayed regular lithium intercalation spectra.