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The possibility of layered melamine-phytate (MEL-PA) as an efficient synergist for intumescent flame retardant (IFR) is explored. The synergistic effects of MEL-PA on polypropylene (PP)/IFR composites are investigated in terms of flammability tests and combustion under forced-flaming condition. The addition of MEL-PA can effectively improve limited oxygen index (LOI) of PP composites. When 2 mass% MEL-PA is incorporated, the LOI value is enhanced from 33.0 to 35.1%. In addition, fire-retardant performance is increased with the addition of MEL-PA. The heat and smoke releases of PP/IFR are greatly reduced by MEL-PA. When IFR is partially replaced by 0.5, 1.0 and 2.0 mass% MEL-PA, total smoke production values are decreased by 27.2%, 34.8% and 57.6%, respectively. Raman spectra analysis indicates that the adding of MEL-PA results in higher graphitization degree of char layer. This work proves that MEL-PA and IFR have a good synergistic effect on flame-retardant PP. [ABSTRACT FROM AUTHOR]

In order to improve its water resistance and compatibility with polymer matrix, ammonium polyphosphate (APP) is modified with melamine‐trimesic acid (MEL‐TA) aggregates by supramolecular self‐assembly technology. Chemical structure and morphology of APP@MEL‐TA are investigated by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM), respectively. Intumescent flame retardant system of APP@MEL‐TA and charring‐foaming agent is introduced into polypropylene (PP) matrix. The flammability and combustion behavior of PP composites are investigated by limiting oxygen index (LOI), UL‐94 vertical burning, and cone calorimetry tests. In terms of LOI values and cone combustion results, APP@MEL‐TA performs better than pristine APP. Char residue of PP composites is investigated by SEM and Raman spectra. Flame retardant mechanisms are proposed based on thermal decomposition, combustion results, and analysis on char residue. [ABSTRACT FROM AUTHOR]

Piperazine cyanurate (PCA) is designed and synthesized via hydrogen‐bonding self‐assembly reactions between piperazine and cyanuric acid. Chemical structure and morphology of PCA are investigated by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The prepared PCA is combined with ammonium polyphosphate (APP) to prepare flame‐retardant polypropylene (PP) composites. Thermostability, flammability, and combustion characteristics of PP composites are analyzed. The maximum thermal decomposition rate of flame‐retarded PP composites has an apparent reduction compared with that of pure PP, and obvious char is left for this intumescent flame retardant (IFR) system of APP and PCA. A high limiting oxygen index value and UL‐94 V‐0 rating are achieved with addition of APP and PCA. In cone calorimetry test, heat and smoke releases of PP are significantly decreased by this IFR system. Gaseous decomposition products during the thermal decomposition of flame‐retardant composites are studied. Chemical structure and morphology of char residues are analyzed. The results illustrate that APP and PCA have a superb synergistic action in the aspect of improvement in fire safety of PP. A possible flame‐retardant mechanism is concluded to reveal the synergism between APP and PCA. [ABSTRACT FROM AUTHOR]

Melamine-phytate (MEL-PA) nanoflakes are formed by supramolecular self-assembly technology using melamine (MEL) and bio-based phytic acid (PA) as the building blocks. This work explores the possibility of this two-dimensional nanomaterial as flame retardant. The layered MEL-PA with the loading of 1, 2 and 3 wt% are incorporated into polypropylene (PP) matrix. MEL-PA is dispersed well in the PP matrix. Thermal stability and flame retardant performance of PP/MEL-PA composites are investigated. Compared with neat PP, the addition of 2 wt% MEL-PA decreases the peak heat release rate from 756 to 608 kW/m2. Char yield of PP is improved by MEL-PA, and the chemical structure and graphitization degree of residual char are studied to reveal flame retardant mechanism. [ABSTRACT FROM AUTHOR]

γ‐Al2O3 nanoflakes are decorated on the surface of graphene nanosheets by hydrothermal method. The chemical structures, composition, and morphology of the graphene nanohybrid are characterized. Alumina nanoflake‐coated graphene nanohybrid is incorporated into polypropylene (PP) matrix by master batch‐based melt mixing method. The effects of alumina‐graphene nanohybrid on the thermal stability and combustion behavior of PP are investigated. More char residue is left for PP composite containing alumina‐graphene nanohybrid. Peak heat release rate of pure PP is greatly decreased by this nanohybrid, corresponding to 30.6% reduction. Fire safety of PP is considerably enhanced. Flame retardant mechanisms are concluded based on the combustion results and char analysis. The barrier effect of graphene and catalytic charring actions of γ‐Al2O3 nanoflakes make the contribution to the enhanced flame retardant properties. [ABSTRACT FROM AUTHOR]

Zirconium phenylphosphonate (ZrPP) nanoplatelets are decorated on the surface of reduced graphene oxide (RGO) based on π–π assembly interactions. The structure, composition, and morphology of ZrPP‐RGO assembly nanohybrid are well characterized. The dispersion of graphene in the nonpolar polypropylene (PP) matrix is improved by this modification. The enhancement mechanisms of dispersion in polymer matrix are clearly demonstrated. Significant improvements in flame retardancy and fire safety of PP are obtained by the incorporation of this assembly nanohybrid. Peak heat release rate and total heat release of PP composite containing 2 wt% ZrPP‐RGO assembly nanohybrid decrease by 35.8% and 23.6%, respectively, compared to those of neat PP. The assembly nanohybrid exhibits higher flame‐retardant effect than the counterparts of RGO and ZrPP. Furthermore, storage modulus of PP is greatly improved by this nanohybrid. This work proposes a novel method to prepare graphene‐based organic–inorganic nanohybrid and will expand the application of graphene. POLYM. COMPOS., 40:E1757–E1765, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

A novel nano-clay flame retardant (HNTs@MEL-PA) is prepared by modifying halloysite nanotubes (HNTs) with supramolecular self-assembly technology using melamine (MEL) and bio-based phytic acid (PA) as the building blocks. Transmission electron microscopy images and Fourier transform infrared spectra show that the surface of HNTs is successfully decorated with MEL-PA supramolecular aggregates by hydrogen bonding. The feasibility of using HNTs@MEL-PA as a flame retardant for polypropylene (PP) is explored. Compared with PP/HNTs composites, the dispersion of HNTs@MEL-PA and its interfacial interactions with PP matrix are greatly improved. Heat release of PP is decreased in a certain degree and its smoke release is greatly reduced by HNTs@MEL-PA. With the addition of 15 wt% HNTs@MEL-PA, total smoke production of PP is decreased from 15.7 to 10.2 m2, indicating the greatly improved fire safety. Flame retardant and smoke suppression mechanisms of HNTs@MEL-PA are proposed based on thermal decomposition results and the analysis on char residue. Image 1 • HNTs were modified by supramolecular self-assembly technology. • Combustion behaviors of PP/HNTs@MEL-PA composites were investigated. • Flame retardant and smoke suppression mechanisms of HNTs@MEL-PA were concluded. [ABSTRACT FROM AUTHOR]

Organically modified ammonium polyphosphate (APP) flame retardant is prepared by supramolecular assembly method using melamine formaldehyde (MF) resin and phytic acid (PA) as building blocks. Surface characteristics of APP are modified, resulting in the enhancements in water resistance, dispersion in the polymer matrix and their compatibility. This supramolecular assembly modified APP (APP@MF-PA) matches well with charring-foaming agent (CFA) to achieve excellent fire safety for polypropylene (PP), and the superiority over conventional APP is observed. Heat, CO and CO 2 releases of PP are greatly decreased by the intumescent flame retardant (IFR) formulation containing APP@MF-PA and CFA. The modification of APP with MF-PA supramolecules are beneficial to improve the yield, insulation properties, graphitization degree and compactness of char. Flame-retardant mechanisms are demonstrated according to the investigations on gaseous and condensed phase products. This novel and facile modification method provides a new strategy for improving the flame-retardant efficiency of IFR. Image 1 • The surface characteristics of APP were modified by supramolecular assembly. • Fire hazards of PP were greatly reduced by this modified APP and CFA. • Flame retardant mechanisms were proposed. [ABSTRACT FROM AUTHOR]

• Nacre-like GO-PTA paper is prepared by evaporation-induced self-assembly method. • Fire sensor-based GO-PTA exhibits ultrasensitive and durable warning response. • Enhancement in fire resistance of GO is attributed to in situ phosphorus doping. A novel nacre-like flame-retardant paper based on graphene oxide (GO), and phytic acid (PTA) is fabricated via evaporation-induced self-assembly. This facile method is time saving and low energy consuming. A facile approach is proposed to improve thermal oxidative stability of GO paper by in situ phosphorus doping during flame exposure. Then fire-alarm system is designed based on the high-temperature thermal reduction characteristic of GO. The GO paper functionalized with PTA (GO-PTA) can provide ultrasensitive, reliable and longtime fire early-warning signal. Fire alarm can be triggered at approximately 0.50 s when GO-PTA samples are attacked by fire. Phosphorus atoms are in situ doped into graphene layers during fire exposure, endowing GO-PTA paper with outstanding thermal oxidative stability, and thus alarm duration time of GO is greatly improved. The work develops advanced fire detection and early-warning sensors that provide reliable and continuous signals, which provide more available time for fire evacuation. [ABSTRACT FROM AUTHOR]

• A novel bio-based flame retardant was synthesized via a simple ionic reaction. • The synergistic effects of IFR on combustion behaviors of PLA were explored. • APP/ATMP-NA-Fe endowed PLA with excellent flame-retardant performance. The high flammability and severe melt-dripping during the combustion are the most marked fire hazards for polyesters, such as polylactic acid (PLA). In this work, a bio-based flame retardant (ATMP-NA-Fe) was successfully synthesized by a simple aqueous ionic reaction by using amino trimethylene phosphonic acid (ATMP), nicotinamide (NA) and FeCl 3 •6H 2 O as raw materials. The ATMP-NA-Fe and ammonium polyphosphate (APP) have good synergistic effects on improving the flame-retardant performance and retarding the combustion melt-dripping of PLA. With a 10 wt% total loading of ATMP-NA-Fe and APP (1:1), the limiting oxygen index value of corresponding PLA composite (PLA3) increases from 20.1% to 32.8%, and it passes UL-94 V-0 rating without melt dripping. The cone calorimetry results show that compared with pure PLA, the peak heat release rate, total heat release and average mass loss rate of PLA3 are reduced by 66.4%, 14.9% and 76.7%, respectively. Via the analysis on the condensed and gas phase products, the flame-retardant mechanism of PLA/APP/ATMP-NA-Fe composites is proposed. This work provides a new approach for improving flame-retardant performance of PLA and promoting the utilization of renewable resource. [ABSTRACT FROM AUTHOR]