Search results for "Clay"

A model for the prediction of the flow curves from interlayer distance and vice versa for intercalated polymer and polymer blend nanocomposites

2015

In this work was proposed a simple model to predict the viscosity and the power law index from the interlayer distance and, vice versa, the interlayer distance from a single flow curve for intercalated polymer nanocomposites. This model cannot be applied to exfoliated nanocomposites or when other interactions are present in the systems.

The preservation of the Agrigento Cathedral

2013

The Agrigento Cathedral was built about nine centuries ago on the edge of a steep slope made up of alternating inclined layers of soft calcarenites and fine-grained soils; its behaviour has never been satisfactory especially as far as the North aisle is concerned. Many corrective measures have been attempted during its lifespan and also a few years ago. They proved invariably unsuccessful. Recent geotechnical investigations, referred to in the paper, permitted to find out that the main cause of the Cathedral distress is a sliding mechanism involving the upper zone of the slope underlying the North aisle; consequently the essential requirement for the preservation of the Cathedral is the sta…

Adsorption of anionic dyes onto natural, thermally and chemically modified smectite clays

2014

Abstract The aim of this study was to determine the adsorption capacity of the smectite clays (from the overburden of the lignite deposit in Belchatow) for two anionic dyes, i.e. Reactive Blue 81 (RB-81) and Direct Blue 74 (DB-74). Additionally, the influence of the thermal and chemical (acid and alkali) clay modifications on the amount of bonded dyes was investigated. The adsorption capacity of the clay (natural and modified) was different for studied dyes and depended on the initial concentration and modification type. All the modified clays adsorbed the dyes at pH>pHPZC as the negatively charged surfaces of their particles (in accordance with the formula: AOH ↔ AO- + H+) prevented the…

Oil solubilization in copolymer and copolymer covered laponite aqueous dispersion

2007

Clay/Non-Ionic Surfactant Hybrid Nanocomposites

2020

This chapter gives an overview of the structural and chemical physical properties of nanocomposites formed by clay minerals and surfactants, which represent a class of materials with promising features for applications in different industrial, biomedical, and environmental applications. Due to their non-toxicity and biocompatibility, a great deal of attention is nowadays devoted to the study of non-ionic surfactants. Among them, block copolymers represent a combination of the properties of common amphiphilic molecules and long polymer chains. These macromolecules can form a great variety of supra-molecular structures generated from self-organization phenomena in aqueous media. Nanostructure…

Sorption of Acid Green 16 from Aqueous Solution onto Low-moor Peat and Smectite Clay Co-occurring in Lignite of Belchatow Mine Field

2015

Celem badań było wyznaczenie pojemności sorpcyjnej iłu smektytowego i torfu niskiego towarzyszących pokładom złóż węgli brunatnych w stosunku do barwnika Acid Green 16 (AG–16) oraz określenie mechanizmu jego wiązania. Wyniki wskazały, że badany torf niski był skutecznym sorbentem barwnika AG-16 w całym zakresie stężeń początkowych (1–1000 mg/dm3), natomiast ił smektytowy – jedynie z zakresie stężeń wysokich (> 250 mg/dm3). W wyniku aktywacji termicznej iłu nastąpił wzrost jego pojemności sorpcyjnej w stosunku do badanego barwnika. Proces sorpcji barwnika przebiegał przy ujemnie naładowanej powierzchni sorbentów i wskazywał, że jednym z mechanizmów wiązania barwnika AG–16 były oddziaływania …

Effect of the extensional flow on the properties of oriented nanocomposite films for twist wrapping

2011

In this study, we examined the mechanical behavior of nanocomposite films based on polyethylene (PE) and pristine PE films. The films were prepared by film blowing and were then cold-drawn at low temperature. The experimental results show that cold drawing significantly enhanced the orientation; with increasing draw ratio (DR), the elastic modulus and tensile strength of the PE films strongly increased, particularly in the presence of the organoclay. To obtain polymeric films suitable for twist wrapping, the films must be sufficiently stiff so that no shrinkage or elastic recovery occur during or after twisting. The elongation at break and the yield strain sharply decreased with orientation…

Predator response to the coloured eyespots and defensive posture of Colombian four‐eyed frogs

2023

Deimatic displays, where sudden changes in prey appearance elicit aversive predator reactions, have been suggested to occur in many taxa. These (often only putative) displays frequently involve different components that may also serve antipredator functions via other mechanisms (e.g., mimicry, warning signalling, body inflation). The Colombian four-eyed frog, Pleurodema brachyops, has been suggested to gain protection against predation through putative deimatic displays where they inflate and elevate the posterior part of their body revealing eye-like colour markings. We exposed stationary artificial frogs to wild predators to test whether the two components (eyespot/colour markings, defens…

Italica (Seville, Spain): use of local marble in Augustan age

2010

This study concerns 51 marble finds made of “Cipollino verde” coming from the ancient city of Italica (north of the modern city of Santiponce, 9 km NW of Seville, Spain), the earliest Roman settlement in Spain, founded in 206 B.C. The aim of this work was to determine their provenance from Greek and Italian quarries or from local quarries worked in the Iberian Peninsula. Thin-section optical microscopy, X-ray powder diffraction, bulk rock chemistry and O, C and Sr stable isotope analyses were carried out. Results were compared with literature data on “Cipollino verde” marbles quarried in southern Euboea (Greece), Apuan Alps (Italy), Almería, Extremoz, Seville (Spain) and Évora (Portugal). T…