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Open AccessArticle

Phosphate Low-Melting Glasses as Synergist in Flame-Retardant Cable Sheath Composition: Performance and Mode of Action

by Diana Amin Alsayed, Rodolphe Sonnier, Belkacem Otazaghine, Patrick Jean, Yves Brocheton and Laurent Ferry

Polymers 2025, 17(19), 2679; https://doi.org/10.3390/polym17192679 - 3 Oct 2025

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Abstract

Nowadays, fiber optic cables are a strategic issue because of their importance in telecommunications. Due to the densification of optic cables and the reduction in polymeric layer thickness, the flammability of the external sheath has to be improved. Three novel flame-retardant compositions using phosphate low-melting glasses (LMGs) as aluminum trihydrate (ATH) synergist were assessed in a polyethylene–ethylene vinyl acetate (PE-EVA) matrix. It was highlighted that LMG at a 10 wt% content reduced the peak and mean value of heat release rate (HRR), respectively, to 142 and 90 kW/m² corresponding to 52% and 42% reduction compared to ATH only. Potassium phosphate LMG was shown to perform better than sodium or zinc phosphate LMG. The improvement was assigned to the formation of an expanded mineral layer at the surface of the material during combustion that acts as a thermal shield slowing down the pyrolysis rate. The structural analysis revealed that the presence of alkaline cations in glasses led to short phosphate chains that resulted in low softening point and low-viscosity liquid. It was evidenced that under heat exposure the melted glass is likely to flow between the dehydrating ATH particles, creating a cohesive layer that expands. Additionally, interactions between ATH and LMG were also evidenced. The new crystalline species may also play a role in the cohesion of the layer. Full article

(This article belongs to the Special Issue Flame-Retardant Polymer Composites II)

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13 pages, 4008 KB

Open AccessArticle

Behavior of Glass-like and Mineral-like Phosphate Compounds with an Immobilized Chloride Mixture in Hydrogen Peroxide Solutions

by Anna V. Frolova, Svetlana A. Kulikova, Kseniya Y. Belova, Sergey S. Danilov and Sergey E. Vinokurov

Energies 2022, 15(17), 6477; https://doi.org/10.3390/en15176477 - 5 Sep 2022

Cited by 1 | Viewed by 2316

Abstract

A new type of high-level waste (HLW) is generated during pyrochemical reprocessing of mixed nitride spent uranium–plutonium nuclear fuel. Such waste is a spent electrolyte, which is a mixture of chloride salts containing approximately 25.7 wt.% LiCl + 31.6 wt.% KCl + 4.1 wt.% CsCl + 5.1 wt.% BaCl₂ + 3.8 wt.% SrCl₂ + 29.7 wt.% LaCl₃, and its immobilization in reliable matrices is an actual radiochemical problem. The structure and hydrolytic stability of sodium aluminoironphosphate (NAFP) glass and a low-temperature mineral-like magnesium potassium phosphate (MPP) matrix, which are promising for spent electrolyte immobilization in the presence of hydrogen peroxide solutions simulating natural water radiolysis products, were studied in this work. The structure of the samples was studied using the SEM-EDS method. It was shown that the initial samples of NAFP glass after leaching in hydrogen peroxide solutions are prone to precipitation of crystalline phases on the surface, which are mainly represented by a mixture of sodium–iron–aluminum pyrophosphates. It was established that the leaching rate of structure-forming components of NAFP and MPP matrices generally increase, but remain at a low level, meeting modern requirements for HLW immobilization. This confirms the effectiveness of the studied matrices for the industrial use of the spent electrolyte. Full article

(This article belongs to the Special Issue Treatment of Radioactive Waste and Sustainability Energy)

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23 pages, 6234 KB

Open AccessArticle

Effect of Gamma Irradiation on Structural Features and Dissolution of Nuclear Waste Na–Al–P Glasses in Water

by Alexey V. Luzhetsky, Vladislav A. Petrov, Sergey V. Yudintsev, Viktor I. Malkovsky, Michael I. Ojovan, Maximilian S. Nickolsky, Andrey A. Shiryaev, Sergey S. Danilov and Elizaveta E. Ostashkina

Sustainability 2020, 12(10), 4137; https://doi.org/10.3390/su12104137 - 19 May 2020

Cited by 9 | Viewed by 3774

Abstract

Structural properties and water dissolution of six sodium–aluminum–phosphate (NAP) glasses have been investigated before and after irradiation by a gamma-ray source based on ⁶⁰Co. Two of these samples were of simple composition, and four samples had a complex composition with radionuclide simulants representing actinides, fission, and activated corrosion products. Samples of the simple composition are fully vitreous, whereas samples of the complex composition contained up to 10 vol.% of aluminum–phosphate, AlPO₄, and traces of ruthenium dioxide, RuO₂. Based on the study of pristine and irradiated glasses, it was established that the radiation dose of 62 million Gray had practically no effect on the phase composition and structure of samples. At the same time, the rate of leaching of elements from the irradiated samples by water was decreased by about two times. Full article

(This article belongs to the Special Issue Nuclear Waste Management and Sustainability)

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