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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]

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]

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]

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]