Guennadi E. Zaikov

Polymer flame retardancy: A new approach

New types of ecologically friendly polymer flame-retardant systems were proposed for Nylon 6,6 and polypropylene [high temperature polymer–organic char former, poly(vinyl alcohol), and silicon–inorganic system]. These systems can act in condensed and gaseous phases. The cone calorimeter and LOI tests indicated the improvement of fire-retardant properties for compositions of flame retardants with Nylon 6,6 and polypropylene in comparison with pure polymers.

The thermo-oxidative degradation of polystyrene

Abstract The kinetics of thermal and thermo-oxidative degradation of polystyrene (PS) alone and in the presence of 4,4′-isopropylidene bis (2,6-dibromophenol) were investigated. It was shown that the retardant affects the thermo-oxidative degradation of PS. Thermal volatilisation analysis (TVA), subambient TVA, FT-IR spectroscopy and GC-MS techniques were used for the separation and characterisation of the various degradation products. The main products of thermo-oxidative degradation were styrene, carbon dioxide, water, benzaldehyde, α-methylstyrene, phenol, phenylacetaldehyde and acetophenone.

Sorption and diffusion of water and organic solvents in poly(β-hydroxybutyrate) films

Abstract The diffusion and solubility of water and organic compounds in poly(β-hydroxybutyrate) (PHB) at room temperature has been investigated. It was shown that the supermolecular structure of PHB films affects sorption of water and the thermostability of specimens. Analysis of the solubility of low molecular compounds in PHB was based on the thermodynamics of the regular solution. Correlation between solubility of compounds in PHB and the parameters of solubility was observed. A dependence of the diffusion coefficient D on the solvent concentration in the polymeric matrix was found.

Innovative type of low flammability varnish based on poly(vinyl alcohol)

A new type of polymer varnish (coating) has been developed, based on poly(vinyl alcohol) oxidized by potassium permanganate in water solution. The flammability of this coating was tested using a cone calorimeter. All tests indicated an increase in the flame retardancy of this polymer coating due to carbonization of cross-linked polymer fragments.

Biodegradation of polymers and adhesion properties of microorganism cells

We demonstrate the possibility of using FTIR-spectroscopy to study the chemical composition of conidia films and to define surface hydrophobicity. It was possible to predict conidium hydrophobicity based on the data obtained for component ratios. This is the defining factor for microorganism adhesion to solid surfaces and for further processes of biodegradation.

Novel Low Flammable Coating Based on Polyvinyl Alcohol

Abstract A new type of polymer varnish (coating) based on Polyvinyl Alcohol was developed using potassium permanganate oxidation in water solution. The flammability of this coating was tested using Cone Calorimeter. All tests on flammability indicated an increase of flame retardancy of this polymer coating due to carbonization of cross-linked polymer fragments.

New aspects of ecologically friendly polymer flame retardant systems

Abstract In the modern polymer industry the different types of polymer flame retardants based on halogens (Cl, Br), heavy and transition metals (Zn, V, Pb, Sb), or phosphorus organic compounds may reduce risk during polymer combustion and pyrolysis, yet may present ecological issues. The overall use of halogenated flame retardants is still showing an up- ward trend, and the preceding concerns have started a definite search for environmentally friendly polymer additives. As a result of these trends, it is quite possible that the available selections of polymer flame retardants will be more limited than in the past.

Flame retardants: poly(vinyl alcohol) and silicon compounds

In the modern polymer industry, the various existing types of polymer flame retardants based on halogens (Cl, Br), heavy and transition metals (Zn, V, Pb, Sb) or phosphorus-organic compounds reduce the risk from polymer combustion and pyrolysis, but may present ecological issues. The overall use of halogenated flame retardants is still showing an upward trend, but the above concerns have started a search for more environmentally friendly polymer additives. As a result it is quite possible that the future available flame retardants will be more limited than in the past.

Stabilization of polymers from the influence of biological media. Kinetic method of biocide efficiency estimation

We show the value of application of kinetic methods for the estimation of biocide activity. We have developed methods of quantitative estimation of biocide efficiency independent of their solubility in water. It is found that inhibited kinetics of microscopic fungal growth on nutriments with biocides is described by a logistic equation. We suggest parameters for the characterization of biocide efficiency. It was found in an investigation of the connection between aging and the biodeterioration processes that: 1. (1) Metabolites of Aspergillus niger microscopic fungus may physically influence the material. This process may proceed during short exposure times, when the concentration of organic acids is low and their diffusion in the material is practically absent. 2. (2) In the case of microorganism influence on a polymer, chemical reactions follow a random law and lead to the decrease of important properties. Degradation products formed during aging facilitate the growth of microorganisms. 3. (3) The kinetics of microorganism growth on polymers with different degrees of aging is described by the same functional dependence, i.e. the macrokinetic regularities of polymer overgrowth do not depend on aging.

Diffusion in polymers with varying accessibility

Abstract This paper considers the problem of describing quantitatively the process of diffusion in polymers attended by plasticization of their amorphous phase. A consequence of such plasticization is that the volume accessible to the penetrant molecules continuously increases during the course of their sorption. Assuming that the rate of relaxation processes is far greater than that of diffusion, an equation has been generated to describe the sorption in a matrix with varying accessibility. A numerical solution of this equation, using experimental data for a polyamide-water system, demonstrates that sorption in a matrix with increasing accessibility is slower than sorption in a hypothetical matrix with constant accessibility and with the same proportion of the amorphous phase. At the same time, the concentration of the penetrant in the former case proves to be higher at any point in the polymer specimen. The results obtained are important for calculating the rate constants for chemical reactions that proceed in a polymer matrix in the diffusion-kinetic mode.