Search

Currently, the flame retardancy of epoxy resin (EP) was achieved at the expenses of the transparency and/or toughness. In the present work, a phosphorus/nitrogen‐containing compound (FDNP) was synthesized by one‐pot method using 9,10‐dihydro‐9‐oxa‐10‐phospha‐phenanthrene‐10‐oxide, furfural and N‐phenyl‐p‐phenylenediamine as raw materials, and further adopted as a functional agent for epoxy resin. The results demonstrated that the FDNP remarkably improved the fire safety of EP. The incorporation of 4 wt% FDNP enabled EP to pass UL‐94 V‐0 rating test and achieve a limiting oxygen index value of 35.5%; meanwhile, the peak heat release rate, total heat release rate and total smoke release were significantly reduced by 41.3%, 41.6% and 72.5% as compared with the pure EP, respectively. What is more, the EP/4 wt% FDNP composite kept almost the same transparency of the pure EP, simultaneously its impact strength was more than doubled as that of the pure EP. Herein, the improved flame retardancy is contributed to a synergistic biphasic flame retardant effect including the formation of a compact protective carbon layer and the release of both non‐combustible gases and phosphorus‐containing radicals. [ABSTRACT FROM AUTHOR]

A compound containing phosphorus/nitrogen/sulfur (named as DOVNPT) was synthesized by the reaction of p‐toluenesulfonamide, vanillin and 9,10‐dihydro‐9‐oxo‐10‐phosphophenanthrene‐10‐oxide, and was adopted to prepare flame retardant epoxy resins (FREPs) using 4,4‐diaminodiphenylmethane as the curing agent. The chemical structure of DOVNPT was verified using Fourier‐transform infrared spectroscopy, 1H and 31P nuclear magnetic resonance. The influence of the DOVNPT content on the thermal stability, fire performance, combustion behaviors, transparency and mechanical properties of the FREPs was investigated in detail. The DOVNPT promoted the decomposition of EP on advance whilst lowered the maximum decomposition rate. With the incorporation of 4 wt% DOVNPT (0.49 wt% phosphorus content), the FREP‐4 achieved a LOI value of 34.4% and a UL‐94 V‐0 rating. The FREP‐4 also gave the lowest peak heat release rate, total heat release and total smoke release, with a reduction of 40.4%, 24.8%, and 28.6% as compared with the pure EP, respectively. The comprehensive analysis of the char residues and gaseous pyrolysis products demonstrated that the DOVPNT displayed good flame retardant effect in both gas phase and condensed phase. Simultaneously, the FREPs presented a comparable transparency and slightly improved mechanical properties as compared with the pure EP. [ABSTRACT FROM AUTHOR]

Due to the energy gap law, the direct fabrication of efficient organic afterglow materials with long emission wavelengths at ambient conditions remains challenging. Here, luminescent dopants with moderate kRISC values of 100–101 s−1 are designed to harvest triplet energies, simultaneously improving afterglow efficiency and maintaining emission lifetimes >0.1 s. Organic matrices with large dipole moments are selected to populate the triplet excited states of the luminescent dopants and suppress their nonradiative decay and quenching. The dopant‐matrix systems exhibit TADF‐type organic afterglow with quantum efficiency of 20% to 60% and emission wavelengths exceeding 600 nm. Because of their singlet excited state nature, the TADF‐type afterglow emitters can efficiently transfer excited energy to rhodamine B or cyanine 5.5 fluorescence dyes for the construction of red and near‐infrared afterglow materials which display promising bioimaging applications. [ABSTRACT FROM AUTHOR]

Nylon 11/ethylene-vinyl alcohol/dicumly peroxide (DCP) blends were prepared using a single-screw extruder. The melting behavior and isothermal crystallization kinetics were investigated using differential scanning calorimetry. The reorganization of nylon 11 crystals is strongly hindered owing to cocrosslinking phenomena. The analysis of the crystallization kinetics demonstrated that the Avrami equation well described the isothermal crystallization process of the primary stage. The spherulites growth kinetics parameters and fold surface free energy were also evaluated. The experimental results confirmed that the presence of DCP increased the crystallization rate. POLYM. ENG, SCI., 48:2354-2361, 2008. © 2008 society of Plastics Engineers, INTRODUCTION In recent years, high barrier polymer blends have attracted much attention due to their prevention of the solvents permeation from plastic fuel tanks and agrochemical bottles, as such permeation [...]

A P/N/Si containing diphenylphosphoramide silicone oil (PASO) was synthesized using amino phenyl silicone oil and diphenylphosphinyl chloride as raw materials. The as‐synthesized PASO displayed better flame retardancy toward polycarbonate (PC) meanwhile maintaining the mechanical performances of PC. At loading level of 1 wt% PASO, UL 94V‐0 rating and a high limited oxygen index value of 31% were achieved for the flame retardant composite in the presence of 5 wt% talc as anti‐dripping agent. Additionally, it gave a tensile strength of 65.5 MPa, elongation at break of 96.4%, and impact strength of 52.6 kJ/m2, which were comparable to the pure PC. The analysis of the char residue after cone calorimeter test and the pyrolysis gaseous products demonstrated that PASO exhibited flame retardant mechanism of both gas and condensed phases. [ABSTRACT FROM AUTHOR]