R. F. Ganiev

Preparation and stabilization of silver nanoparticles in liquid water-soluble starch matrix

82 Studies of the properties of silver nanoparticles car� ried out in recent years [1–3] convincingly demon� strate that they possess unique biocidal, optical, chemical, and other properties. The practical use of these properties of silver nanoparticles opens up broad opportunities for the design of electronic, optical, and

Effect of mechanical activation on the structure of adsorbed polymer layers on the surface of pigment particles in aqueous disperse systems

In the context of the wide use of disperse systems, it is important to develop new methods for improving their quality and controllably changing their properties, including the production of aqueous suspensions of highly stable finely dispersed pigments used as components of paints and varnishes, oil and fuel additives, etc. Among the problems involved are surface phenomena; polymer adsorption on surfaces of different nature, especially in mechanical activation; and interfacial

Effect of mechanical activation on the viscoelastic properties of solutions of starch-sodium carboxymethyl cellulose mixtures

Starch and cellulose are the most important natural polymers reproduced under natural conditions. The sharp interest in these substances is caused by the severity of environmental problems since such polymers serve as feedstock for producing environmentally friendly biodegradable materials. Currently, cellulose is used for producing a wide spectrum of its ethers and esters, among which high priority is given to sodium carboxymethyl cellulose. Mixtures of sodium carboxymethyl cellulose with starch can be a basis for obtaining liquid biocomposite (and nanobiocomposite) materials with specified properties and functions. As an efficient tool for controlling the properties of solutions of polymer mixtures, mechanical treatment (wave, shock, shear, etc.) has found increasing use [1, 2]. The present work dealt with studying the effect of mechanical shear on the viscoelastic properties of solutions of a starch‐sodium carboxymethyl cellulose mixture. The objects of study were potato starch (PS) and 70/450O sodium carboxymethyl cellulose (NaCMC). Binary mixtures of biopolymers with weight ratios 1 : 3, 1 : 1, and 3 : 1 were obtained by mixing preliminarily prepared 4% aqueous solutions at 293 K. Mechanical treatment of polymers and their mixtures was carried out in a rotary cavitation device. The rotor speed was 6000 rpm, which corresponded to the shear rate 9.5 × 10 3 s ‐1 . The duration of mechanical treatment was 30 s, and the treatment temperature was 298 K. The rheological properties of biopolymer solutions were studied on a Reotest-2 rotary viscometer with a cylinder‐cylinder working unit in the shear rate range 1.5‐1310 s ‐1 at 298 K. The viscometer was equipped with a recorder that automatically monitors the transition range of viscoelastic deformations that precedes the establishment of the stationary flow mode of polymer systems. The viscoelastic properties of the polymer solutions were analyzed with the use of the Maxwell model [3]. The intrinsic viscosity of the polymer systems was determined from the relative viscosity of dilute solutions of the individual polymers by the common procedure [4]. Relative viscosity was measured at 293 K with a VPZh-2 Ostwald capillary viscometer with a capillary diameter of 1.2 mm. The mean-root-square error of viscosity measurements was ± 0.3% .