T. V. Druzhinina

Oxidation of polyvinyl alcohol fibres in the presence of phosphorus-containing compounds

The oxidation temperature-time regime that results in carbon fibre materials (CFM) with a yield of approximately 30% and a 94–95% concentration of carbon was established based on a study of the fundamental characteristics of thermal transformations of polyvinyl alcohol (PVA) fibres in the presence of phosphorus-containing compounds. It was shown that the effective active energy of decomposition of oxidized PVA fibres and their capacity for coke formation increase in the presence of [NH4]2HPO4. The effect of the increase in the elasticity of CF caused by the action of the phosphorus-containing compound on cross-linking of the carbon during high-temperature treatment was determined.

Effect of high-temperature treatment on thermochemical transformations of oxidized polyvinyl alcohol fibres

The thermochemical transformations of PVA fibres containing diammonium phosphate were investigated in high-temperature treatment in nonoxidizing medium in the 500–900°C region. It was shown that deep thermochemical transformations that make it possible to conduct subsequent carbonization at a lower temperature (approximately 800°C) take place in the selected conditions of thermooxidation of PVA fibre (temperature of 200°C, duration of 16 h, presence of diammonium phosphate).

Thermal properties of polyvinyl alcohol fibres in the presence of a phosphorus-containing catalyst

The thermal properties of polyvinyl alcohol in the presence of phosphorous-containing and other inorganic compounds were investigated. The catalytic role of a phosphorus-containing fireproofing compound — diammonium phosphate — in thermooxidative decomposition of PVA was revealed. It was found that dehydration of PVA is intensified, the activation energy of decomposition of PVA increases, and its coke-forming power also increases in the presence of (NH4)2HPO4.

Effect of the nature of polyethylenepolyamine solvent in the heterogeneous reaction of polymer-analog transformations of polyvinyl alcohol-polyglycidyl methacrylate graft copolymer

The effect of the character of the medium on the occurrence of the heterogeneous reaction of amination of PVA-PGMA graft copolymers with polyethylenepolyamine was investigated, A kinetic effect was established when polyethylenepolyamine solutions were used. The effect of the solvent on the completeness of the reaction of PGMA α-oxide groups with polyethylenepolyamine amino groups, caused by swelling of the solid phase of the polymer and a change in the reactivity of the functionally active groups of the reacting compounds, was demonstrated.

Reaction of α-oxide groups in graft copolymers of polycaproamide and polyglycidyl methacrylate with thiourea

The effect of a composite of graft copolymers of polycaproamide and polyglycidyl methacrylate on the reaction rate of α-oxide groups with thiourea was determined. A supermolecular effect in the heterophase macromolecular reaction of transformation of α-oxide groups with thiourea was revealed. It was found that the degree of polymer-analog transformations of α-oxide groups into thiirane groups in PCA-PGMA graft copolymers is on the level of 55–70%.

Fabrication of chemisorption amino-containing cellulose fibres

These studies revealed the effect of the polymer matrix on graft polymerization of glycidyl methacrylate. The high efficiency of the Cuc−H2O2 redox system (RDS) in graft polymerization of glycidyl methacrylate (GM) to hydrated cellulose (HC) fibre was demonstrated. Amino-containing HC chemisorption fibres with a SEC of 2.9 meq/g were fabricated.

Characteristics of transformation of α-oxide groups of graft polyglycidyl methacrylate in reacting with low-molecular-weight amines during fabrication of polycaproamide chemisorption fibre

The quantitative characteristics of heterophase ammation of PCA-PGMA graft copolymer with low-molecularweight aliphatic amines are reported. The conditions for obtaining chemusorption fibres with SEC of 2.5–3.0 mmole/g were determined. The high activity of PCA chemisorption fibres containing substituted amuno groups with respect to gaseous SO2 was demonstrated within broad limits of the relative humidity of the gas-air medium.

Research on fabrication of carbon fibre sorbents based on cellulose acetates

The basic characteristics of thermal transformations of fibres obtained as a result of alkaline hydrolysis of cellulose acetates in the stage of oxidation and carbonization were investigated. A correlation was established between the composition, structure, and properties of the starting polymeric raw material and the carbonized materials. The expediency of conducting hydrolysis of the ester bond of cellulose acetates, which results in splitting of acetyl groups in the low-temperature region, was substantiated. The important possibility of obtaining carbon fibre sorption materials based on acetate fibres was demonstrated.

Characteristics of radical graft polymerization of glycidyl methacrylate to polyvinyl alcohol fibre on the boundary of the solid and liquid phases

In studying the characteristics of graft polymerization of glycidyl methacrylate (GMA) on the boundary of the solid (polyvinyl alcohol (PVA) fibre) and liquid phases, it was shown that the concentration order of the reaction rate in the monomer and H2O2 was similar to the order for classic radical polymerization processes. The specific effect of the thermodynamics on the kinetics of the process was established in a relatively narrow temperature region (50–80°C), manifested by significantly different activation energies.

Some features of the heterophase emulsion graft polymerization of glycidyl methacrylate to polycaproamide fibre

Conclusions-- The special features of the graft polymerization of glycidyl methacrylate to polycaproamide fibre have been discovered. An anomalous effect of the copper compound and of hydrogen peroxide in the composition of the redox system on the rate of graft polymerization of glycidyl methacrylate has been found.-- The graft polymerization in the presence of the redox system Cuc-H2O2 which has been examined is characterized by a high rate and high monomer conversion and takes place essentially without formation of homopolymer.-- The relationships which have been found indicate a high efficiency and an ecological cleanness of the graft polymerization process at hand.