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The natural basalt fiber (BF) was incorporated into EVA composites with environmental‐friendly nickel alginate‐brucite based flame retardant (NiFR), to further improve the flame‐retardant effect and mechanical properties. The flame retardancy of EVA composites were characterized by LOI, UL 94, and cone test. With 55 wt% loading, 3BF/52NiFR had the highest LOI value of 31.9 vol.% in all fiber reinforced composites and pass UL 94V‐0 ratting. And comparing to 55B composite with untreated brucite, 3BF/52NiFR decreased peak of heat release rate by 47.8%, total heat release by 21.9%, and total smoke production by 35.5% and kept more residue 54.0% during cone test. Moreover, 3BF/52NiFR also enhanced the mechanical properties of composites by better compatibility with EVA matrix. BF/NiFR exert synergistic flame‐retardant effect major in promoting charring effect in condensed phase during combustion. The fire‐resisted and rigid BF into the char layer reinforced the intensity of protective barrier which prolonged the residence time of pyrolysis carbonaceous groups degraded from EVA matrix, resulting in less heat and smoke release. [ABSTRACT FROM AUTHOR]

Abstract: A series of flame retardant formulations of solid bisphenol A bis(diphenyl phosphate) (S-BDP) and organo-montmorillonite (OMMT) were prepared based on polycarbonate (PC) by a melt compounding procedure. OMMT was well dispersed into the matrix showing an intercalated–exfoliated morphology. S-BDP and OMMT exhibit a synergistic effect in the vertical burning test (UL-94) but an antagonistic effect in the limiting oxygen index (LOI) evaluation. Thermogravimetric analysis (TGA) of the flame retarded PC system both under nitrogen and air was performed. Migration of S-BDP and OMMT towards the surface occurs during combustion. The introduction of OMMT could especially enhance the thermal-oxidative stability of the material, which is further confirmed by the analysis of the char residues by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). [Copyright &y& Elsevier]

A zeolite imidazole framework (ZIF-67) was assembled onto the surface of ammonium polyphosphate (APP) for preparing a series multifunctional flame-retardant APP-ZIFs. The assembly mechanism, chemical structure, chemical compositions, morphology, and specific surface area of APP-ZIFs were characterized. The typical APPZ1 and APPZ4 were selected as intumescent flame retardants with dipentaerythritol (DPER) because of their superior unit catalytic efficiency of cobalt by thermogravimetric analysis. APPZ1 and APPZ4 possessed 6.8 and 92.1 times the specific surface area of untreated APP, which could significantly enhance the interfacial interaction, mechanical properties, and migration resistance when using in ethylene-vinyl acetate (EVA). With 25% loading, 25% APPZ4/DPER achieved a limiting oxygen index value of 29.4% and a UL 94 V-0 rating, whereas 25% APP/DPER achieved a limiting oxygen index value of only 26.2% and a V-2 rating, respectively. The peak of the heat release rate, smoke production rate, and CO production rate respectively decreased by 34.7%, 39.0%, and 40.1%, while the char residue increased by 91.7%. These significant improvements were attributed to the catalytic graphitization by nano cobalt phosphate and the formation of a more protective char barrier comprised of graphite-like carbon. [ABSTRACT FROM AUTHOR]

Polycarbonate (PC) is flame retarded by polyphenylsilsesquioxane (PPSQ) with a ladder structure. The flame retardant mechanism of PC/PPSQ composite between the gas phase and condensed phase is investigated using a thermo-gravimetric analyzer coupled with Fourier transform infrared spectrometry (TG-FTIR), pyrolysis/gas chromatography and mass spectrometry (Py–GC/MS), cone calorimeter and scanning electron microscope-energy disperse spectroscopy (SEM-EDS). TG-FTIR results indicate that the thermal stability of the PC/PPSQ composite is marginally better than that of PC, and evolving gaseous products during the pyrolysis and infrared analysis, such as CO 2, ester groups, aromatic components and isopropyl groups, are found. Py–GC/MS results show that higher concentrations of micromolecule gas products are released from the PC/PPSQ composite, which is beneficial for creating an intumescent char layer. Cone calorimeter tests and temperature variations of the top and bottom char layers indicate that the PC/PPSQ composite and the char layer have a good heat insulation effect. The results of char residues from FTIR indicate that SiO 2 is composed of fumed silica which is attached to the internal surface char, white SiO 2 is exposed to outside when the char is burned broken and the condensed phase of top char is composed of Si–O–Si and Si–C. The main structure of the bottom char is inorganic carbon. The SEM-EDS analysis indicates that the condensed phase of the char residue structure is composed of three elements, C, O and Si, the content of O and Si is much higher than C. [ABSTRACT FROM AUTHOR]

The synergistic flame retardant effects and mechanisms of nano-Sb2O3 in combination with aluminum diethlyphosphinate (AlPi) in poly(ethylene terephthalate) (PET) were investigated by means of limiting oxygen index (LOI), UL 94 vertical burning test, thermogravimetric analysis (TGA) and thermogravimetric analysis coupled with Fourier transform infrared spectrometer (TGA-FTIR). A good dispersion of nano-Sb2O3 and AlPi into polymer matrix was achieved as showed by high resolution transmission electron microscope (HRTEM) and scanning electron microscope (SEM). Obvious synergistic effects between nano-Sb2O3 and AlPi were observed for flame retardant PET when the mass ratio of AlPi and nano-Sb2O3 was from 1:1 (4 wt%) to 4:1 (10 wt%). LOI value of flame-retarded PET was increased to 33.6% and UL 94 rating passed V-0. Adding nano-Sb2O3 to AlPi remarkably changed the thermo and thermo-oxidative degradation behaviors of AlPi, as the initial and maximum-rate decomposition temperature of AlPi/nano-Sb2O3 shifted and more residues were obtained at 800 °C. Compared with PET/AlPi, two processes were believed to promote the formation of more carbonaceous char for PET/AlPi/nano-Sb2O3: one was the catalytic effect of nano-Sb2O3 on the cross-linking phenomenon, the other one was the condensation reaction between Sb–OH on the surface of nano-Sb2O3 and diethylphosphinic acid. Furthermore, the interaction between nano-Sb2O3 and AlPi in the condensed phase happened mainly over the temperature range of 460–600 °C. All these results were confirmed by evolved gas and residue analysis. [ABSTRACT FROM AUTHOR]

A novel flame retardant compound (TDBA) with multiple phosphaphenanthrene groups was synthesized and confirmed by chemical structural and elemental characterization. Contrastive analysis on thermal decomposition behavior showed that the two kinds of bridge bonds linking phosphaphenanthrene groups in TDBA caused a wider decomposition temperature range, contributing to inhibiting combustion in relatively longer time. The application of TDBA in epoxy thermosets suggested that, TDBA capacitated the limited oxygen index of thermosets to surpass 35% and 4 wt.% or more loadings of TDBA made 4,4′-diamino-diphenyl methane curing thermosets pass UL94 V-0 rating especially. During combustion, the incorporated TDBA induced the matrix to decompose earlier, reduced the fuels production, reduced burning intensity and inhibited the combustion reaction of fuels in gaseous phase, and promoted the charring behavior of thermosets in condensed phase. The pyrolysis of TDBA proceeded along two main directions, namely substituted phosphaphenanthrene and bisphenol-A. Through releasing massive phenolic derivatives, PO free radicals and other certain phosphorus-containing substances, TDBA is capable to exert free radical quenching effect in gaseous phase, and to promote charring behavior to form compact residue with barrier effect on heat and fuels transportation in condensed phase. This bi-phase joint action mode from TDBA endowed epoxy thermosets with excellent flame retardancy. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the acid catalysis of boron phosphate (BP) to model compound dipentaerythritol (DPER) which acted as char source during the thermal degradation and combustion. Various amounts of BP were added in DPER and then the thermal degradation and combustion behaviors were studied by means of thermogravimetric analysis (TGA) and microscale combustion calorimeter (MCC). Evolved Gases were evaluated using TGA-FTIR; solid residues were fully characterized by FTIR, X-ray photoelectron spectroscopy (XPS), Raman analysis and scanning electron microscopy (SEM). The results of TGA and MCC showed that the addition of BP leaded to the earlier thermal degradation of DPER and increased the amount of char residues, significantly decreased the peak heat release rate of DPER; the results of TGA-FTIR, XPS, Raman analysis and SEM revealed that the presence of BP accelerated the dehydration of DPER, kept more carbon and oxygen elements in condensed phases, promoted the formation of compact and stable char layer. This study indicated that Lewis acidic and Brønsted acidic sites in BP altered the single degradation pathway and catalyzed the crosslinking and char forming of DPER. BP maybe as a potential acid source applied in intumescent flame retardant polymers in future. [ABSTRACT FROM AUTHOR]

A bio-based Mg(OH) 2 @tin phytate@zinc tannate (MH@PASn@TAZn) composite was synthesised via layer-by-layer assembly method. Chemical bonds formed by chelating metal ions with phytic acid and tannic acid were involved in this synthesis. MH@PASn@TAZn was then incorporated into PVC and its effects on flame retardancy, smoke suppression and mechanical properties were investigated. The core-shell structure and binding states between each layer (Mg–O–P, P–O–C) of the composite were examined. The limiting oxygen index (LOI) and cone calorimeter test results showed that the addition of 10 ph MH@PASn@TAZn effectively enhanced the flame retardancy and smoke suppression of PVC. The LOI value of the 10 ph MH@PASn@TAZn-incorporated PVC sample increased to 30.3% because of the combination of the gas dilution effect of vapor generated by the degradation of MH and synergistic catalytic carbonisation of PASn and TAZn. The second peak heat release rate, second peak smoke production rate and total smoke production of PVC/MH@PASn@TAZn composite decreased by 40.8%, 72.2% and 35.2%, respectively. The increase in the interfacial contact area of PASn and the enhancement of interfacial interaction of TAZn significantly improved the tensile strength, elongation at break, and impact strength of PVC. This study presents a promising approach to synthesise flame-retardant PVC with excellent smoke suppression and mechanical properties. Image 1 • A novel bio-based MH@PASn@TAZn was designed via layer-by-layer assembling technique and incorporated into flexible PVC. • The core-shell structure and binding states between each layer (Mg–O–P, P–O–C) was characterized and confirmed. • The flame retardancy and smoke suppression of the composites were improved dramatically by the synergistic action. • The mechanical property was significantly improved with assistance of assembly layer. [ABSTRACT FROM AUTHOR]

To meet the increasingly stringent requirements for the fire safety and mechanical properties of epoxy thermoset (EP) in advanced manufacturing industry, two kinds of phosphaphenanthrene/siloxane cluster-like molecules with multiple reactive groups (TriDSi and TetraDSi) were synthesized, and then linked into the cross-linked network of epoxy thermoset, separately. The incorporated TriDSi and TetraDSi improved the fracture toughness and flame retardant performance of epoxy thermoset, simultaneously. The impact strength of 6%TriDSi/EP and 6%TetraDSi/EP both increased by more than 120%, compared with that of neat epoxy thermoset. Meanwhile, 6%TriDSi/EP and 6%TetraDSi/EP both passed UL94 V-0 rating with a limited oxygen index of 35.2% and 36.0%, respectively. Moreover, the heat release of burning thermoset was also suppressed significantly by incorporated cluster-like molecules. Through segmer-aggregation toughening effect and group-aggregation flame retardant effect, the cluster-like molecules TriDSi and TetraDSi endowed epoxy thermoset with superior fracture toughness and significantly lowered combustibility. This study provides a promising choice to manufacture advanced epoxy thermoset materials. Image 1 [ABSTRACT FROM AUTHOR]