To reveal the effect of chlorine substituents in the ring of aromatic amine on the synthesis process of benzoxazine monomer and on its polymerization ability, as well as to develop a fire-resistant material, a previously unreported benzoxazine monomer based on 3,3′-dichloro-4,4′-diaminodiphenylmethane was obtained in toluene and mixture toluene/isopropanol. The resulting benzoxazine monomers were thermally cured for 2 h at 180 °C, 4 h at 200 °C, 2 h at 220 °C. A comparison between the rheological, thermal and fire-resistant properties of the benzoxazines based on 3,3′-dichloro-4,4′-diaminodiphenylmethane and, for reference, 4,4′-diaminodimethylmethane was made. The effect of the reaction medium on the structure of the oligomeric fraction and the overall yield of the main product were studied and the toluene/ethanol mixture was found to provide the best conditions; however, in contrast to most known diamine-based benzoxazines, synthesis in the pure toluene is also possible. The synthesized monomers can be used as thermo- and fire-resistant binders for polymer composite materials, as well as hardeners for epoxy resins. Chlorine-containing polybenzoxazines require more severe conditions for polymerization but have better fire resistance.

A novel type of phosphazene containing an additive that acts both as a catalyst and as a flame retardant for benzoxazine binders is presented in this study. The synthesis of a derivative of hexachlorocyclotriphosphazene (HCP) and meta-toluidine was carried out in the medium of the latter, which made it possible to achieve the complete substitution of chlorine atoms in the initial HCP. Thermal and flammability characteristics of modified compositions were investigated. The modifier catalyzes the process of curing and shifts the beginning of reaction from 222.0 °C for pure benzoxazine to 205.9 °C for composition with 10 phr of modifier. The additive decreases the glass transition temperature of compositions. Achievement of the highest category of flame resistance (V-0 in accordance with UL-94) is ensured both by increasing the content of phenyl residues in the composition and by the synergistic effect of phosphorus and nitrogen. A brief study of the curing kinetics disclosed the complex nature of the reaction. An accurate two-step model is obtained using the extended Prout–Tompkins equation for both steps.

As a result of this work, a previously unreported benzoxazine monomer based on 3,3'-dichloro-4,4'-diaminodiphenylmethane was obtained, characterized by 1H and 13C NMR spectroscopy, and its thermal and rheological properties were studied. A comparison between the properties of benzoxazines based on diamines (3,3'-dichloro-4,4'-diaminodiphenylmethane and 4,4’-diaminodimethylmethane). The effect of the reaction medium on the structure of the oligomeric fraction and the overall yield of the main product was studied. The synthesized monomers can be used as thermo- and fire-resistant binders for polymer composite materials, as well as hardeners for epoxy resins.

A novel type of phosphazene containing additive that act both as catalyst and as flame retardant for benzoxazine binders is presented in this study. The synthesis of a derivative of hexachlorocyclotriphosphazene (HCP) and meta-toluidine was carried out in the medium of the latter, which made it possible to achieve complete substitution of chlorine atoms in the initial HCP. Thermal and flammability characteristics of modified compositions are revealed. The modifier catalyzes the process of curing and shifts the beginning of reaction from 222.0 C for pure benzoxazine to 205.9 C for composition with 10 phr of modifier. The additive decreases the glass transition temperature of compositions. Achievement of the highest category of flame resistance (V-0 in accordance with UL-94) is ensured both by increasing the content of phenyl residues in the composition and by the synergistic effect of phosphorus and nitrogen. Brief research of the curing kinetics disclosed the complex nature of the reaction. An accurate two-step model is obtained using extended Prout-Tompkins equation for both steps.

The influence of epoxyphosphazene-modifying additives on the features of the hot curing process of epoxy-amine composition was studied by the rotational viscometry method. The modification caused an acceleration of the curing process, changed rheokinetics of viscosity increase, especially the stage molecular mass growth of linear chains became almost twice shorter for composition with 30% modifier than for unmodified one. We suggest the reason for these changes is the polyfunctionality of epoxyphosphazene, which finally results in high-density network formation. In cold curing process the bulkiness of epoxyphosphazene molecule and the lack of heat for its motion results in incomplete cure. Thus, in order to cope with these difficulties hot curing systems were proposed and studied.