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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]

Due to the inherent defect of flammability of polypropylene (PP), a novel and highly efficient carbon microspheres@layered double hydroxides@copper lignosulfonate (CMSs@LDHs@CLS) flame retardant was designed and prepared, which was attributed to the strong electrostatic interaction between carbon microspheres (CMSs), layered double hydroxides (LDHs) and lignosulfonate as well as the chelation effect of lignosulfonate on copper ions, and then it was incorporated into the PP matrix. Significantly, CMSs@LDHs@CLS not only observably improved its dispersibility in PP matrix, but also simultaneously achieved excellent flame retardant properties for composites. With the addition of 20.0 % CMSs@LDHs@CLS, the limit oxygen index of CMSs@LDHs@CLS and PP composites (PP/CMSs@LDHs@CLS) reached 29.3 % and achieved the UL-94 V-0 rating. Cone calorimeter tests indicated that the peak heat release rate, total heat release and total smoke production of PP/CMSs@LDHs@CLS composites exhibited declines of 28.8 %, 29.2 % and 11.5 %, respectively, compared with those of PP/CMSs@LDHs composites. These advancements were attributed to the better dispersibility of CMSs@LDHs@CLS in PP matrix and illustrated that CMSs@LDHs@CLS observably reduced fire hazards of PP. The flame retardant property of CMSs@LDHs@CLS might relate to condensed phase flame retardant effect of char layer and catalytic charring of copper oxides. [ABSTRACT FROM AUTHOR]

In this paper, a functionalized layered double hydroxide (LDH-LS@Ni(OH) 2) flame retardant was designed and fabricated based on a multi-modifier system consisting of lignosulfonate (LS) and Ni(OH) 2 and used as a novel flame retardant for polypropylene (PP). In this multi-modifier system, LS as a compatibilizer and charring agent to improve compatibility and char yield, and Ni(OH) 2 was utilized to improve the graphitization of char residual, resulting in a PP/LDH-LS@Ni(OH) 2 composite with higher thermal stability. With the addition of LDH-LS@Ni(OH) 2 was only 15 wt%, the PP/LDH-LS@Ni(OH) 2 composite achieved a limiting oxygen index (LOI) of 30.8% and passed the UL-94 V-0 rating. At the same time, the peak heat release rate (PHRR), total heat release (THR), and total smoke production (TSP) were significantly reduced by 62.7%, 29.5%, and 46.2%, respectively. The flame retardant properties of LDH-LS@Ni(OH) 2 were mainly due to the catalytic charring effect of the transition metal elements and the physical barrier effect of the hydrotalcite. More specifically, as a highly efficient flame retardant, LDH-LS@Ni(OH) 2 has promising potential in reducing the fire hazards of PP composites. [Display omitted] • The dual modified LDH flame retardant was synthesized by co-precipitation method. • A novel hybrid flame retardant of S/Ni-containing (LDH-LS@Ni(OH) 2) was prepared. • PP/LDH-LS@Ni(OH) 2 (15 wt%) increased the LOI to 30.8% and passed the UL-94 V-0 rating. [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]

A novel fire retardant containing nitrogen and sulfur anion (triazine-sulphonate) was synthesized and then was directly intercalated into the interlayer of Mg/Al hydrotalcite (LDHs) by calcination-reconstruction manner to obtain nitrogen- and sulfur- containing flame retardant (LDH-NS) for polypropylene (PP) matrix. The microstructure and combustion properties of LDH-NS and its hybrid with PP composite (PP/LDH-NS) have been comprehensively characterized. XRD and SEM/EDS indicated that LDH-NS exhibited better dispersion than CO 3 2– intercalated LDHs (LDH-C) in the PP matrix. TGA showed that the thermal stability of PP/LDH-NS composites was enhanced. Cone calorimetry tests (CCT) illustrated that the peak heat release rate (PHRR), total heat release (THR) and total smoke release (TSR) of PP/LDH-NS composites were 255.8 kW m−2, 61.3 MJ m−2 and 205.7 m2 m−2, respectively, which exhibited declines of 69.7%, 43.1% and 75.0% compared with those of Neat PP. Furthermore, the PP/LDH-NS composites presented a limiting oxygen index (LOI) value of 28.6% and exhibited a vertical burning test (UL-94) V-1 rating at 30 wt% loading LDH-NS. All of these revealed that triazine sulfonate-modified LDHs significantly improved the fire performance of the PP matrix by increasing the char formation of PP/LDH-NS composites. Moreover, by adding the LDH-NS as filler for the PP matrix could promote the mechanical properties of PP/LDH-NS composites. The 30 wt% LDH-NS shown a significant fire retardance and thermal stability of PP matrix. Unlabelled Image • A fire retardant containing N and S anion (triazine-sulphonate) was synthesized. • Triazine-sulphonate pillared layered double hydroxides (LDH-NS) was prepared. • The 30 wt% LDH-NS shown a significant fire retardance and thermal stability of PP. • Triazine-sulphonate significantly promoted the flame retardancy of hydrotalcite to PP. [ABSTRACT FROM AUTHOR]

• An efficient and bio-based alginate pillared layered double hydroxides (SA@LDHs) was successfully prepared. • LOI value of PP/30 % SA@LDHs reached 30.9 % and samples can pass UL-94 V-0 rating. • Synergistic flame-retarding effect of alginate and layered double hydroxides was found. An efficient and bio-based alginate pillared hydrotalcite (SA@LDHs) was fabricated via calcination-reconstruction manner with sodium alginate (SA) and hydrotalcite (LDHs-C), and used as novel flame retardant for polypropylene (PP). The morphologies and combustion properties of SA@LDHs and its hybrid with PP composites (PP/SA@LDHs) had been characterized by SEM, TGA, cone calorimetry, LOI and UL-94 measurements. With 30 wt% loading, the SA@LDHs achieved a LOI value of 30.9 % and a UL-94 V-0 rating, whereas the LDHs-C exhibited only LOI value of 27.6 % and a UL-94 V-1 rating. The peak heat release rate, total heat release and total smoke production of PP/SA@LDHs were 260.8 kW m−2, 61.3 MJ m−2 and 8.2 m2, respectively, which presented declines of 69.2 %, 42.8 % and 32.2 % compared with those of Neat PP. These improvements could be attributed to the presence of the radical-trapping effect of SA, which leading to promote PP chains to participate in the carbonization process. [ABSTRACT FROM AUTHOR]