Synthesis of oligomeric epoxycyclotriphosphazenes and their properties as reactive flame-retardants for epoxy resins

Hydroxyaryloxycyclophosphazenes containing 2–4 OH groups have been synthesized by the substitution of chlorine atoms of hexachlorocyclotriphosphazene via the reaction with sodium phenolates of halogenophenols followed by the interaction with sodium monophenolate of diphenylolpropane. Oligoepoxyphosphazenes (OEPs) with molecular masses up to 2000 and the contents of epoxy groups, phosphorus, and halogens atoms about 5–8, 5–8, and 5–11%, respectively, have been obtained via the interaction of the aforementioned phosphazenes with epichlorohydrin. The curing of the OEPs with amines or acid anhydrides gives rise to the formation of self-extinguishing composites. The incorporation of the OEPs (5–75 wt %) into commercial epoxy resins followed by their curing, results in the formation of composites with excellent nonflammability or capability of self-quenching, and good dielectric, heat resistant and mechanical properties. It has been established that mixtures of common epoxides with different amounts of the OEPs can be synthesized by a “single-reactor” method. © 2017 Taylor & Francis Group, LLC

Synthesis of oligomeric epoxycyclotriphosphazenes and their properties as reactive flame-retardants for epoxy resins

Hydroxyaryloxycyclophosphazenes containing 2–4 OH groups have been synthesized by the substitution of chlorine atoms of hexachlorocyclotriphosphazene via the reaction with sodium phenolates of halogenophenols followed by the interaction with sodium monophenolate of diphenylolpropane. Oligoepoxyphosphazenes (OEPs) with molecular masses up to 2000 and the contents of epoxy groups, phosphorus, and halogens atoms about 5–8, 5–8, and 5–11%, respectively, have been obtained via the interaction of the aforementioned phosphazenes with epichlorohydrin. The curing of the OEPs with amines or acid anhydrides gives rise to the formation of self-extinguishing composites. The incorporation of the OEPs (5–75 wt %) into commercial epoxy resins followed by their curing, results in the formation of composites with excellent nonflammability or capability of self-quenching, and good dielectric, heat resistant and mechanical properties. It has been established that mixtures of common epoxides with different amounts of the OEPs can be synthesized by a “single-reactor” method. © 2017 Taylor & Francis Group, LLC

Study of the crystalline electric field in PrxLa1-xAl3

Nous avons réalisé des expériences de diffraction inélastiques de neutrons sur des échantillons polycristallins de PrxLa1-xAl3 (x = 1,0 ; 0,75 ; 0,50 ; 0,25) dans le but d'étudier la corrélation entre le champ cristallin (CEF) et les caractéristiques du comportement des électrons de conduction dans les intermétalliques de terres rares. Nous faisons une analyse qualitative des relations observées en tenant compte de l'effet de la variation du paramètre de réseau sur la base du modèle de charges ponctuelles, de la présence possible de distorsions locales de symttrie et d'un certain nombre de mécanismes de relaxation.Inelastic neutron scattering experiments were performed on PrxLa1-xAl3 polycrystalline specimens (x = 1.0 ; 0.75 ; 0.50 ; 0.25). Relationships of energetic positions and widths of a number of peaks in neutron scattering spectra with Pr concentration were obtained. A qualitative analysis of observed relationships is made by taking into account the effect of the lattice parameter variation on the basis of the effective point charges (EPC) model, the possible presence of local distortions of symmetry and a number of relaxation mechanisms