A phosphorous flame retardant of phosphoric acid , P , P ′-1,4-phenylene P , P , P ′, P ′-tetraphenyl ester (PAPTE) was synthesized by diphenyl chlorophosphate and hydroquinone . The structural features of PAPTE were investigated with mass spectra (MS), infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) and high-performance liquid chromatograph (HPLC) methods. The thermal behavior of PAPTE was analyzed with differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) instruments. A static analytic method was used to measure the solubilities of PAPTE in the several selected pure solvents, which are methanol, ethanol, acetone, ethyl acetate , acetonitrile , methyl acetate , toluene, ether, n -propanol, i -propanol, where the temperatures range is from 288.25 to 333.45 K. The experiments were also performed in the binary mixed solvents of acetone and methanol. Several thermodynamic models were used to correlate the experimental solubility data, such as Wilson, nonrandom two-liquid (NRTL), UNIQUAC equations. The solubility data of PAPTE in binary solvents were correlated with the modified Wilson model. The calculated results showed that those models can excellently reproduce the experimental data and the UNIQUAC equation reveals the better ability in correlation. Using the Scatchard–Hildebrand methodology, the activity coefficients, solubility parameter of the solute and the partial molar excess enthalpies at infinite dilution were calculated.
The development of methods for recycling of thermosetting resin is difficult due to their structure. To regulate the flame retardancy and chemical degradation behavior of epoxy (EP), a phenylphosphonate based EP monomer (DGEP) was prepared and cured using 4,4-diamino diphenylmethane (DDM). For comparison, bisphenol A EP (DGEBA/DDM) was also prepared. The modes of flame retardancy and chemical degradation have been investigated. The DGEP/DDM displays a UL-94 V0 rating while the DGEBA/DDM may not be classified in the UL-94 test. Moreover, DGEP/DDM is stable in most solvents and is degraded after 40 min in a solution of methanol/sodium hydroxide (NaOH)/water (H 2 O) at 50 °C, while DGEBA/DDM is stable under the same conditions. Degradation occurs by hydrolysis and alcoholics of phenylphosphonate in the main chain of EP under alkaline conditions. In addition, DGEP/DDM has a similar glass transition temperature and tensile properties as those for DGEBA/DDM. The introduction of phenylphosphonate into EP may represent a useful method for the preparation of flame retardant and recyclable EP.
2D@0D multidimensional nanoparticles (WC@TDP) were first prepared by decorating WS2 2D nanosheets (WC) with titanium diphenylphosphonate (TDP) 0D nanoparticles, which were derived from the hybridization of diphenylphosphinic acid and TiO2. The chemical structure and micromorphology of the modified 2D nanosheet were confirmed, and TDP nanoparticles were tightly attached to the exfoliated WC nanosheets through noncovalent interactions. Afterward, WC@TDP was incorporated into the epoxy resin (EP), showing the improved dispersion and distribution in the thermosetting matrix. Because TDP exhibits catalytic charring activity and WC acts as a physical barrier, such EP/WC@TDP nanocomposites exhibited the enhanced fire safety, including flame retardation and smoke suppression during burning. The composite containing 8 wt % WC@TDP passed UL94 V-0 rating with a limiting oxygen index increased from 26.0 to 34.0 vol %. Compared with those of neat EP, the peak heat release rate, total heat release rate, and total smoke release of EP/8WC@TDP were reduced by 42%, 17%, and 38%, respectively, without sacrificing the mechanical properties of the nanocomposites.
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