Ebru Günister

Biocomposite films based on alginate and organically modified clay

Sodium alginate/sodium montmorillonite hybrid films were prepared by casting from the suspension of sodium alginate and different clay samples. Clay samples had been modified with a cationic surfactant, a cationic polymer, and a small polar molecule, respectively. Benzethonium chloride, polyethyleneimine and urea were used as clay modifiers. The composite films begin to disintegrate at a higher temperature and with less weight loss than the pure alginate films. This suggests an enhancement of the film thermal stability due to the modification of the alginate with clay samples.

Interactions of BDTDACl and DTABr Surfactants with Montmorillonite in Aqueous Systems

In this study, the effect of the two cationic surfactants (benzyldimethyltetradecylammonium chloride (BDTDACl) and dodecyltrimethyl-ammonium bromide (DTABr)) on the electrokinetic and rheologic properties of Na-montmorillonite dispersion (3% w/w) has been investigated at their concentrations between 0 and 10 mmol/L. Experimental results reveal that cationic surfactants are attached on the surface of negatively charged clay particles and also they penetrate into the interlayer of clay particles. The intercalation of surfactants with clay minerals is shown to lead to an increase in the interlayer spacing of montmorillonites by X-ray diffraction. The Fourier transform infrared (FTIR) spectra obtained from the modified bentonite products reveal the characteristic absorption bands. The morphology of bentonite dispersions was analyzed by scanning electron microscopy (SEM). Both X-ray diffraction data and scanning electron micrographs of intercalated montmorillonites indicate that most of the montmorillonites are dispersed randomly in the organo-clay dispersion.

Influence of Cationic Polymers on the Rheological Behavior of Bentonite Clay Suspensions

In this study, the rheological behaviours of the bentonitic clay suspensions were determined as a function of the addition of three types of cationic polymers, namely polyethyleneimine (PEI), polydimethyldiallylammonium chloride (PDDA) and polybrene (PB). The addition of polymers at concentrations ranging between 10-10 g/l affect rheological properties and stabilities of bentonite dispersions. The results are interpreted according to the type of polymers and concentrations. Introduction Bentonite which is a kind of smectite group clay mineral is almost made up 80 % of montmorillonite and contains a crystal lattice with three layers. Bentonite clays are widely used in various industrial products and processes such as paints, coatings, ceramics, pesticides, pharmaceuticals, cosmetics, cement, and drilling fluids to modify the rheology and control the stability of systems. The adsorption of polymers modifies the surface properties, rheology and suspension stability of clays, which is of great technological importance. So far, the interaction of small electrolytes, cationic and anionic surfactants, and nonionic polymers with clay components has been widely investigated. However, the studies on polyelectrolyte and clay interaction are scarcer. Clay particles are capable of aggregating in three different arrangements, namely , face-to-face, edge-to-face, and edge-to-edge. The Bingham yield value (extrapolated shear stress) and plastic viscosity are a criterion of particle-particle interaction. In this study, the effect of the addition of PEI, PDDA and PB on the rheological and electrokinetic properties of the 2 % bentonitic clay dispersions have been investigated. The aim of the study is to investigate and to understand the role and mechanism of cationic polymer addition on the flow behaviour of bentonite.