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A series of novel organic and/or inorganic-intercalated MgAl layered double hydroxides (S x Mo y -LDH) were designed and prepared via calcination-reconstruction, where the organic anion was stearic (S) and inorganic anion was MoO 4 2− (Mo). The intercalation of stearic and/or MoO 4 2− anions into the interlayer galleries of the LDH host layers was controlled by adjusting the mass ratios (x / y) of stearic acid to (NH 4) 2 MoO 4 , in which the stearic-intercalated LDH was obtained above the 1: 1 of the x / y mass ratio, and the MoO 4 2−-intercalated LDH was synthesized below the 1: 1 of the x / y mass ratio. Especially at x / y mass ratio of 1: 1, stearic and MoO 4 2− anions were co-intercalated into the interlayers of the S 1 Mo 1 -LDH to confer excellent flame-retardant properties. The morphology, chemical composition and structure of the as-prepared S 1 Mo 1 -LDH determined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy and energy dispersive spectrometer (SEM/EDS) and thermogravimetry (TG) confirmed the co-intercalation of stearic and MoO 4 2− anions into the interlayer galleries. After adding the S x Mo y -LDH materials into polypropylene (PP) matrix, the flame retardant performance of the PP-composites was significantly enhanced compared with the neat PP. It was also noticed that different interlayer anions could provide different retardant performances, and the stearic-MoO 4 2−-co-intercalated LDH (S 1 Mo 1 -LDH) exhibited the highest thermostability and the best flame retardant performance owing to the synergistic effect of the interlayer stearic and MoO 4 2− anions as well the LDH host layers. Therefore, it was possible to obtain a certain intercalation state of the organic and inorganic anions by modulating the mass ratios (x / y) of organic to inorganic anions. Unlabelled Image • The organic and/or inorganic-intercalated MgAl-LDH, was successfully prepared. • At x/y mass ratio of 1: 1, stearic and MoO 4 2− anions were co-intercalated into the interlayers of the S 1 Mo 1 -LDH. • The S 1 Mo 1 -LDH provided excellent fire resistance to PP matrix owing to the interlayer stearic, MoO 4 2− and LDH. [ABSTRACT FROM AUTHOR]

A novel and environmentally friendly lignin-based surfactant sodium lignosulfonate (SLS) modified layered double hydroxide (LDH) flame retardant (LDH-LS) was fabricated via co-precipitation method, and subsequently incorporated into polypropylene (PP) matrix to obtain the PP and LDH-LS composites (PP/LDH-LS) by melt blending method. The XRD, FT-IR and XPS results indicated that SLS had successfully modified LDH by adsorbing on the surface of the LDH nanosheet. The WCA and SEM results revealed that the hydrophobic property of LDH-LS had been evidently improved, and it displayed a more homogeneous dispersion than virgin LDH in the PP matrix. Furthermore, cone calorimetry tests (CCT) illustrated that the peak heat release rate (PHRR), total heat release (THR), and total smoke release (TSR) of PP/LDH-LS composites exhibited declines of 62.9%, 25.1%, and 43.3% compared with those of Neat PP, respectively. Besides, the PP/LDH-LS achieved a LOI value of 29.4% and a UL-94 V-0 rating, whereas the PP/LDH showed only a LOI value of 25.2% and a UL-94 V-2 rating at 20 wt% loading. These improvements of flame retardant properties can be attributed to that the well-dispersed LDH-LS and synergistic flame retardancy between LDH and SLS. [ABSTRACT FROM AUTHOR]

To gain high efficiency flame retardant, the twin organic anions intercalated layered double hydroxides (PD x CA y -LDH) were designed and prepared via calcination-reconstruction, where the organic anions were pentaerythritol diphosphate (PD) and cyanuric acid (CA). The morphology, chemical composition and structure of the PD x CA y -LDH materials were characterized, revealed that the PD x CA y -LDH materials were successfully intercalated by the PD and CA anions in single or combining form. The incorporation of the PD x CA y -LDH with ethylene vinyl acetate copolymer (EVA) not only could significantly improve the thermal stability of EVA matrix but also promote the formation of char layer during combustion, owing to the combined advantages of CA, PD and LDH. It was found that the flame retardancy of the PD x CA y -LDH depended on the mass ratio of PD to CA anions, where the PD 7 CA 3 -LDH with a 7:3 mass ratio of PD/CA had the best flame retardancy due to the presence of an excellent char layer. The EVA/PD 7 CA 3 -LDH composite achieved a LOI value of 28.0% and a UL 94 V-0 rating compared with the EVA/LDH composite with 19.5% and a HB rating, and the peak heat release rate (PHRR) and total heat release (THR) decreased to 340.2 kW∙m−2 and 132.7 MJ∙m−2, respectively. These improvements could be attributed to the catalyzing carbonization of the PD and CA to EVA matrix to form more protective char layers. Unlabelled Image • Organic anion-intercalated layered double hydroxides (PD x CA y -LDH) were successfully prepared. • Both organic anions (PD and CA) were inserted into the interlayers of the LDH in respective and/or combining modes. • The effectively-combined effect of PD, CA and LDH could improve the flame retardancy of EVA composites. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel hierarchical CMSs@LDH@PZN nanospheres with double shells are synthesized. • CMSs@LDH@PZN has well compatible and outstanding thermostability in PP. • CMSs@LDH@PZN enhances the flame retardancy and toxic smoke suppression of PP. Developing advanced performance polypropylene (PP) composites with less smoke, eco-friendly and efficient flame retardants (FRs) has been a growing focus of research. In particular, it was significant to reduce the emissions of smoke and toxic gases generated during the burning of PP so that it meets green and safe industrial requirements. In this work, a CMSs@LDH@PZN hierarchical core–shell framework was designed and synthesized by using carbon microspheres (CMSs) and layered double hydroxides (LDHs) nanosheets connected to CMSs by electrostatic forces with polyphosphazene (PZN). The structure, composition and morphology of CMSs@LDH@PZN were characterized by SEM, TEM, FT-IR, XRD and TG, and the results were shown the triumphant preparation of the well-designed hierarchical core–shell structure CMSs@LDH@PZN. Additionally, the total smoke production, peak heat release rate and total heat release rate of PP/CMSs@LDH@PZN composites were decreased by 56.2%, 41% and 43.4%, respectively. With the addition of 20 wt% CMSs@LDH@PZN alone, the PP/CMSs@LDH@PZN composites reached a V-0 rating in the Vertical combustion tester (UL-94), and had a limiting oxygen index (LOI) value of 29.6%. Moreover, the heat release and toxic smoke emission were significantly lessened, which can be own to the adsorption of core–shell hybrid materials and the barrier effect of the P and N element crosslinked carbon layer. Herein, this work extends the idea of preparing multipurpose high-performance composites and designs and synthesizes an eco-friendly and efficient flame retardant with a double shell structure. [ABSTRACT FROM AUTHOR]

A novel and bio-based adenosine triphosphate (ATP) pillared Mg Al layered double hydroxide (LDHs-ATP) was fabricated via calcination-reconstruction, followed by the incorporation of a highly efficient flame retardant into polypropylene (PP). The XRD result indicated that the interlayer channel of LDHs-ATP was increased to 16.6 Å. Indeed, the increase of the LDHs-ATP interlayer spacing promoted the uniform dispersion and thermal stability, which were further proved by the SEM and TG-DTG results. As expected, the PP/LDHs-ATP composite reached a LOI value of 29.1% and created a UL-94 V-0 rating with only 20 wt% LDHs-ATP loading. Furthermore, CCT illustrated that the peak heat release rate (PHRR), total heat release (THR) and total smoke release (TSR) of PP/LDHs-ATP composite exhibited a series of decreases of 55.9%, 39.5% and 56.4%, respectively, compared with that of Neat PP. [Display omitted] • A bio-based ATP pillared hydrotalcite (LDHs-ATP) was successfully fabricated. • With 20 wt% LDHs-ATP, the PP/LDHs-ATP reached LOI of 29.1% and got UL-94 V 0 rating. • The improvements attributed to synergistic effect from LDHs and ATP. [ABSTRACT FROM AUTHOR]