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Polyvinyl chloride (PVC) is the most widely used general flame-retardant plastic worldwide; however, the large number of plasticizers added during processing significantly reduces its flame-retardant property. To prepare a new type of PVC material with highly efficient flame retardancy and smoke suppression, antimony trioxide (Sb2O3), talc powder, hydromagnesite, and zinc borate were added in different proportions to PVC to explore the flame-retardant properties, thermal weight, smoke density (Ds), and mechanical properties of the composite materials. Results showed that the limiting oxygen index value of each group was higher than 27% after adding talc powder, magnesite, and zinc borate to replace part of the Sb2O3. This value was within the refractory-grade level and indicated a good flame retardancy performance. The replacement effect was in line with the experimental expectation. The lowest Ds peak value was 656.4 when the flame retardants were added with 10 wt% Sb2O3, 50 wt% hydromagnesite, 20 wt% talc, and 20 wt% Zn3BO6. Compared with pure Sb2O3 as a flame retardant, the Ds peak value decreased by 46.7%. The thermogravimetric decomposition temperature of the composites in each group was generally higher than that of the group with pure Sb2O3 as a flame retardant, increasing by 45.3 °C. The thermal stability of the composites was improved, and the elongation at the break and tensile strength were 234.9% and 25.8 MPa, respectively, indicating good mechanical properties. The results showed that using compound flame retardants to replace most of the Sb2O3 is an effective technique for obtaining good flame retardancy and mechanical properties of PVC. This study, not only reduced the manufacturing cost of flame-retardant PVC, but also effectively reduced its smoke density and the time to reach the highest smoke density, which provided a research reference for the application and promotion of flame-retardant PVC. [ABSTRACT FROM AUTHOR]

Organically modified montmorillonite (OMMT) and Ni2O3 were simultaneously introduced into flame‐retardant linear low‐density polyethylene/ethylene‐vinyl acetate/magnesium hydroxide (LEM) composites. Compared with the LEM composite, the thermal stability, and tensile properties of LEM/ remained basically unchanged when 5 wt% of OMMT/Ni2O3 was substituted for MH. The LOI value increased a little from 27.2 to 27.7%. The data from cone calorimeter test showed that the first and second peak heat release rate was reduced by 19% and 67%, respectively. The total heat release and total smoke production showed a significant reduction by 18% and 36% after incorporation of OMMT/Ni2O3, respectively. The mechanism study indicated that the combination of OMMT/Ni2O3 cooperates promote the carbonization of the polymer itself into carbon naotubes, which form a more cohesive char layer with magnesium hydroxide during combustion. This is the core factor responsible for the synergistic effect on reducing the heat release and smoke production in the LEM composite. [ABSTRACT FROM AUTHOR]

In this study, a magnesium phosphate whisker (DPM‐H) was synthesized by the acid–base neutralization reaction between magnesium hydroxide and 10‐hydroxy‐9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO‐OH) at 120°C. A new synergistic intumescent flame retardant (IFR) for epoxy resin (EP), which was composed of DPM‐H and ammonium polyphosphate (APP) was thoroughly studied. When the IFR loading was 8%, with the DPM‐H to APP weight ratio at 1:7, the prepared flame‐retardant EP (EPDA‐2) passed the vertical burning tests (UL‐94) V‐0 rating and obtained the limiting oxygen index (LOI) value of 29.3%. Microscale combustion calorimetry (MCC) results showed that the total heat release (THR) of EPDA‐2 reduced by 32.1% compared with pure EP. Meanwhile, the addition of DPM‐H can partially solve the problem of the decrease of the EP mechanical property caused by the addition of APP. Compared with the flame‐retardant EP with the 8% loading of APP, the impact strength of EPDA‐2 increased 152.3%. [ABSTRACT FROM AUTHOR]

Brucite was modified with oleic acid (OA) and the effect of OA on flame retardancy of brucite in low‐density polyethylene (LDPE) composites was investigated. Fourier transform infrared spectroscopy, X‐ray diffraction, and particle size analysis were used to examine the structural changes of the OA modified brucite. Flammability of the LDPE/brucite composites with different OA content was characterized by thermogravimetric analysis, limiting oxygen index (LOI), UL‐94 test, and microscale combustion calorimetry. The results showed that when brucite was modified with OA, magnesium oleate was formed on the brucite surface. The brucite particle size and the relative intensity of the (101) diffraction peak of brucite decreased. When the content of OA and brucite in the composite were 6 and 40 phr respectively, the prepared LDPE composite displayed better flame retardancy than the corresponding OA free LDPE composite: the LOI value increased from 22.2% to 24.9%, and the peak heat release rate decreased from 678 to 546 kW/m2. The influence of OA on the improvement of flame retardancy of brucite in LDPE/brucite composite was due to the efficient dispersion of brucite in LDPE matrix and the structural changes of brucite, caused by the reaction of OA with brucite. [ABSTRACT FROM AUTHOR]

Although the rigid cross‐linked polyvinyl chloride (c‐PVC) foam has excellent mechanical properties, there are still problems of unsatisfactory thermal insulation performance, flame retardancy, and smoke suppression. So how to simultaneously improve the thermal insulation and flame retardant properties of c‐PVC foam is still a challenge. Herein, the combination of copper powder and molybdenum trioxide (Cu/MoO3) is used to prepare c‐PVC composite foams. The cell structure, thermal conductivity, thermal stability, limiting oxygen index (LOI), and smoke density of the c‐PVC composite foams are characterized. The results showed that, on the one hand, the cell density and thermal insulation performance are improved (31.24 mW m−1 K−1) due to the good heterogeneous nucleation and infrared reflection of the copper powder. On the other hand, when the mass ratio of Cu/MoO3 is 4/1, the best synergistic catalytic effect to promote char formation achieved the highest LOI value of 30.1, and the smoke density rating (SDR) is reduced by 27%. This work is beneficial to the design and application of c‐PVC foams with high performance. [ABSTRACT FROM AUTHOR]

Poly(butylene succinate)/magnesium hydroxide (PBS/Mg(OH)2) composites were prepared by melt compounding to investigate the effect of particle size on the flame retardancy of PBS. Their flammability properties were investigated by limiting oxygen index, UL-94, and cone calorimeter tests, which suggested that the medium-sized Mg(OH)2-5 µm displayed the best flame retardancy. The residual char structure were analyzed and indicated that Mg(OH)2-5 µm could form a better protective layer than other sized particles, leading to the better flame retardancy to PBS. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Biodegradable poly(butylene succinate)/nanosized carbon black (PBS/CB) nanocomposites were prepared by melt compounding to investigate the effect of CB on flammability and mechanical properties of PBS. In the nanocomposites, CB displayed some positive effect on improving the flame retardancy of PBS, mainly on the decrease of peak of heat release rate, the increase of limited oxygen index value, and the inhibition of melt dripping. It was contributed to the formation of a good carbon layer during combustion and of a network structure in the PBS matrix. Moreover, a good balance on mechanical performances of PBS/CB nanocomposites was achieved with enhanced stiffness and high toughness, which was ascribed to the compatibilization of PBS- g-MA, leading to a good dispersion of nanofillers and strong matrix-nanoparticle interaction. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Nanosized carbon black (CB) was introduced into polypropylene/carbon nanotubes (PP/CNTs) nanocomposites to investigate the effect of multi-component nanofillers on the thermal stability and flammability properties of PP. The obtained ternary nanocomposites displayed dramatically improved thermal stability compared with neat PP and PP/CNTs nanocomposites. Moreover, the flame retardancy of resultant nanocomposites was greatly improved with a significant reduction in peak heat release rate and increase of limited oxygen index value, and it was strongly dependent on the content of CB. This enhanced effect was attributed mainly to the formation of good carbon protective layers by CB and CNTs during combustion. Rheological properties further confirmed that CB played an important role on promoting the formation of crosslink network on the base of PP/CNTs system, which were also responsible for the improved thermal stability and flame retardancy of PP. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A novel organophosphorus containing spiro and caged bicyclic phosphate, 3,9-Bis-(1-oxo-2,6,7-trioxa-1-phospha-bicyclo[2.2.2]oct-4-ylmethoxy)-2,4,8,10-tetraoxa-3,9-diphospha-spiro[5.5]undecane 3, 9-dioxide (SBCPO), was synthesized and characterized by Fourier transform infrared (FTIR), hydrogen-1 nuclear magnetic resonance (NMR) and phosphorus-31 NMR. The flame retardancy of polypropylene (PP) containing the novel intumescent flame retardant (IFR) based on the combination between SBCPO and melamine (MA) was studied by limiting oxygen index (LOI), UL-94 test and cone calorimeter test. Results indicated that this combination showed the excellent flame retardancy for PP at appropriate proportions (with the total loading of 30 wt. % and SBCPO: MA = 4:1). The value of LOI was as high as 31.6, and the rating in UL94 reached to V-0. Moreover, the HRR and THR of IFR/PP decreased significantly in comparison with that of neat PP. The scanning electron microscopy results indicated that the incorporation of SBCPO could induce the formation of intumescent char layer, which retarded the degradation and combustion process of PP. The thermal oxidative degradation of the PP samples at different temperature was analyzed by FTIR. The thermal stabilities of the composites were further investigated by thermogravimetric analysis. It was found that the amount of residues was increased greatly with the addition of SBCPO that remained in the form of polyaromatic stacks and phosphoric or polyphosphoric acid at the residual chars. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The controlled carbonization of polymers is one of the most important polymer reactions. It represents the conversion process of polymeric precursors into carbonaceous materials in a "controlled" manner. In this review, we summarize the research progress on the controlled carbonization of (waste) polymers in preparing functional carbon materials with well-defined microstructures, fabricating advanced polymer composites with enhanced flame retardancy, and converting waste polymers into high value-added nanocarbon materials. The carbonization mechanisms of polymers with different compositions and chain structures are highlighted. How to match the degradation reaction of polymers with the carbonization reaction of the degradation products is addressed to improve the carbonization efficiency and optimize the growth of carbon materials. The applications of (waste) polymer-derived carbon materials in electrochemical energy storage and environmental remediation are reviewed. Current existing limitations and future perspectives are also given. [ABSTRACT FROM AUTHOR]

• A series of compounds (xCTAB@AMP) were synthesized by modifying AMP with different molar fractions of CTAB. • 50CTAB@AMP and ADP showed more excellent synergistic flame retardant effects by combined gas-phase and condensed-phase flame retardancy. • EP/50CTAB@AMP/ADP show excellent flame-retardant and antibacterial properties. In this work, we synthesized a series of compounds, denoted as xCTAB@AMP, by incorporating varying different molar fractions of cetyltrimethylammonium bromide (CTAB) into ammonium phosphomolybdate (AMP). The effects of CTAB modification on the surface characteristics, morphology and hygroscopicity of AMP were studied. Moreover, we explored the combined flame-retardant impact between xCTAB@AMP and aluminum diethylphosphinate (ADP) when incorporated into epoxy resin (EP), as well as the resulting composite's mechanical properties, thermal stability and antibacterial properties. The EP composite containing 50 molar percent CTAB-modified AMP (EP/50CTAB@AMP/ADP) demonstrated remarkable flame retardancy, achieving a UL-94 V-0 rating and increasing limiting oxygen index (LOI) to 30.0%. This formulation significantly lowered the peak heat release rate (PHRR) to 452 kW/m2, a 65% reduction to that of EP, and the total heat release (THR) to 68 MJ/m2, a 24% decrease to that of EP. Additionally, compared to EP, the peak smoke production rate (PSPR) of this composite was decreased by 30% (0.28 m2/s), the total smoke production (TSP) was reduced by 25% (30.2 m2), and peak carbon monoxide release rate (PCOP) was diminished by 34% (0.038 g/s). The combination of 50CTAB@AMP and ADP in the EP matrix exhibited an exceptional synergistic flame-retardant effect. Concurrently, the CTAB modification bolstered the interfacial interactions between AMP and the EP matrix, which enhanced the mechanical properties of EP/AMP/ADP composites. As a result, the tensile strength and elongation at break of the EP/50CTAB@AMP/ADP composite increased by 13% and 15%, respectively, compared to the EP/AMP/ADP. Moreover, the 50CTAB@AMP maintained its inherent antibacterial activity, which endowed the EP/50CTAB@AMP/ADP composite with a potent inhibitory effect against Staphylococcus aureus, a common pathogenic bacterium. [ABSTRACT FROM AUTHOR]

[Display omitted] • Imidazole-based liquid compounds containing different P oxidation states were synthesized for curing EP. • EP-DCPPI and EP-PPOAI show the combined flame-retardant mechanism of gas-phase and condensed-phase flame retardancy. • EP-DCPPI and EP-PPOAI show excellent flame-retardant, mechanical properties and heat resistance. In this work, two phosphorus-containing liquid imidazole compounds with different phosphorus oxidation states (1,1′-(phenylphosphanediyl)bis(1 H -imidazole) (DCPPI) with + 1 valence phosphorus, and imidazole-phenylphosphate (PPOAI) with + 3 valence phosphorus) were designed and synthesized. Both of DCPPI and PPOAI were used as curing agents to obtain intrinsic flame-retardant epoxy resin (EP-DCPPI and EP-PPOAI), in which the imidazole group was used as the curing group of EP, and the phosphorus-containing group was directly connected to the EP crosslinking network. On the one hand, the efficient flame-retardant groups containing + 1 or + 3 valence phosphorus were incorporated into the EP system to obtain excellent flame-retardant properties; on the other hand, the introduction of phenylphosphine or phenoxyphosphine groups in the molecular chain of EP greatly enhanced the interaction between molecular chains, adjusted crosslinking density and endowed EP with excellent tensile strength and toughness. Compared with imidazole cured EP (EP-MZ), the peak heat release rate (PHRR) of EP-15DCPPI and EP-15PPOAI decreased by 70 % and 68 %, and the total heat release rate (THR) decreased by 37 % and 36 %, respectively. Meanwhile, EP-15DCPPI passed UL-94 V-0 rating, and the limiting oxygen index (LOI) reached 36.1 %. EP-15PPOAI passed UL-94 V-1 rating and the LOI reached 29.1 %. The flame-retardant mechanism was analyzed and discussed. Compared with EP-MZ, the dynamic and static mechanical properties of EP-15DCPPI and EP-15PPOAI were enhanced simultaneously, and the glass transition temperature (T g) was obviously increased. [ABSTRACT FROM AUTHOR]

A reactive flame retardant containing DOPO and aromatic imine (DOPO-AI) is synthesized. Adding 20 wt% of DOPO-AI reduces heat release and increases mechanical properties of epoxy thermosets. The addition of DOPO-AI does not affect T g and toughness of epoxy thermosets. For improving the flame-retardant performance of epoxy thermosets without sacrificing other properties, a novel aromatic imine-containing DOPO-based bisphenol, DOPO-AI, was synthesized. Diglycidyl ether bisphenol F epoxy resin (DGEBF) reacted with DOPO-AI first, followed by curing with 4, 4′-diaminodiphenylmethane (DDM). When the mass of DOPO-AI was 25% of DGEBF, the resulting epoxy thermoset EP/20DOPO-AI exhibited the V-0 rating with the limiting oxygen index of 35.4%. In the cone calorimetry test, the peak heat release rate and total heat release of EP/20DOPO-AI showed the reduction of 26% and 27%, respectively, compared to those of DGEBF/DDM (EP). The mechanism of DOPO-AI in reducing heat release and increasing char-form ability of EP/DOPO-AI was studied. Interestingly, the mechanical and thermal mechanical properties of EP/20DOPO-AI were improved, although the crosslinking density was much lower than that of EP. The tensile strength and storage modulus of EP/20DOPO-AI were increased by 13% and 5%, while the glass transition temperature and the elongation at break were kept, compared with those of EP. The high rigidity of DOPO and aromatic imine was the reason for the improvement of the mechanical properties of EP/20DOPO-AI. Furthermore, EP/20DOPO-AI showed a small reduction in thermal stability, compared with that of EP. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, ammonium phosphomolybdate (AMP) and aluminum diethylphosphinate (ADP) acting as temperature-response microparticles, were incorporated into epoxy resin (EP) together to promote fire safety and dynamic mechanical performance of EP composites at the same time. Both ADP and AMP acted as chemical inertness fillers to enhance the EP matrix at the normal service temperature and processing temperature. When the temperature rose after heating or even burning, both ADP and AMP presented chemical functions. On one hand, AMP exhibited excellent catalytic charring activity and smoke suppression efficiency. On the other hand, the combination between AMP and ADP in the EP/AMP/ADP composites showed excellent synergistic effects in improving the flame retardancy of EP. Compared to the case of EP, the peak heat release rate (PHRR) of EP/AMP/ADP composites (1.2 wt% AMP and 3.6 wt% ADP) was decreased by 54%, the total heat release (THR) was reduced by 25%, and the total smoke production (TSP) was reduced by 25%. Meanwhile, the UL-94 V-0 rating was obtained, and the limiting oxygen index (LOI) of the composite was increased from 26.2 to 31.2%. The mechanism of flame retardancy was analyzed and discussed. In addition, compared with EP, EP/AMP/ADP composites showed a higher dynamic mechanical property without affecting the glass transition temperature. [Display omitted] • The combination of AMP/ADP as temperature-response microparticle shows a synergistic effect in improving fire safety of EP. • The introduction of AMP and ADP changes the degradation process and degradation products of EP. • Both ADP and AMP acted as chemical inertness fillers to enhance EP matrix at the normal service temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • Highly intumescent char layer with core–shell structure was formed during combustion of PC/PBS composites. • The core–shell char layer is composed of an outer porous structure and an inner lamellar structure. • Linear PDMS with terminal Si-H is the key intermediate to join reaction for forming core–shell char. • The addition of 2 wt% PBS reduce the pSPR of PC by 63.2%, increase the LOI to 31.2% and pass the UL94 V-0 rating. A rare charring behaviour was found during the combustion of polycarbonate (PC) composites containing polyborosiloxane (PBS), in which a highly intumescent char layer with core–shell structure was formed. Particularly the core–shell structure is composed of an outer porous structure and an inner lamellar structure, which can effectively isolate external heat radiation and limit the diffusion of degradation products and oxygen. PC/PBS-X composites with 2 wt% PBS-X showed excellent flame retardancy without compromising mechanical properties, including passing the UL-94 V-0 rating and increasing the limiting oxygen index (LOI) to 31.2%. Compared to PC, the peak heat release rate (pHRR) and peak smoke production rate (pSPR) in the case of PC/PBS-1 composites were reduced by 63.2% and 45.5%, respectively. The mechanism for promoting the flame retardancy of PC by PBS-X was studied. The results showed that the PBS decomposed to form linear polysiloxane oligomer with terminal Si-H bond (L-PDMS-H), which reacted with the degraded products of PC to quickly form intumescent char layer with core–shell structure during the combustion. This is the reason why to PBS presented the striking effect on improving flame retardancy of PC. [ABSTRACT FROM AUTHOR]

It is still a great challenge to develop epoxy resin/glass fabric (EP/GF) composites with well-balanced enhancements on flame retardancy and mechanical properties. Herein, a novel strategy that polyhydric SiO 2 coating assistant to graft organophosphorus (DOPO) onto GF was developed for simultaneously improving flame retardancy and mechanical properties of EP composites. The grafting amount of DOPO could reach to 43.64 wt% via the helpful bridging of polyhydric SiO 2 , so that EP composites displayed excellent flame retardancy with the LOI of 37.2%, the V0 rating on UL-94 and a 63.3% decrease on PHRR in cone calorimeter test. According to the analysis of char morphology and structure, the flame retarded mechanism was mainly ascribed to the enhanced barrier effect of a continuous and intergrow char layer, which was composed of GF@SiO 2 as framework and P-containing condensed carbon as stuffing. Meanwhile, EP composites exhibited outstanding mechanical performances with 35% and 60% increases on tensile strength and impact strength respectively, which resulted from the special molecular structure of GF@SiO 2 - g -DOPO with strong interfacial adhesion with EP chains via hydrogen bond and chemical bond. In summary, this work will be favorable to design multifunctional polymer composites with well-balanced comprehensive performances, and expand their widespread applications in high-end fields. [Display omitted] • A novel polyhydric SiO 2 coating assistant to graft organophosphorus onto GF. • The grafting amount of DOPO could reach to 43.64 wt%. • Excellent flame retardancy with LOI of 37.2%, V0 rating on UL-94 and a 63.3% decrease on PHRR. • Outstanding mechanical performances with 35% and 60% increases on tensile strength and impact strength respectively. • The corresponding enhancement mechanisms on flame retardancy and mechanical performances were revealed. [ABSTRACT FROM AUTHOR]

In this work, we demonstrated a new method for rapidly forming a three-dimensional network porous char layer during the combustion of PP composite foam, based on the combination of intumescent flame retardant (IFR) with expandable graphite (EG) and carbon nanotubes (CNTs). The IFR was composed of pentaerythritol (PER) and ammonium polyphosphate (APP) with a mass ratio of 1:2. Compared to PP composite foams with 40% IFR (PP/40IFR), the PP/EG/CNTs/IFR composite foams we designed could preserve the original foam shape and show excellent flame retardancy after combustion due to the formation of a complete porous char layer. It was found that the EG aggregates violently expanded during combustion and offset the shrink of cellular structure, which can blocks the heat transfer from outside to inside and protect the inner material from the fire. At the same time, the CNTs could bind expanded EG aggregates tightly through the interaction between CNTs and EGs. Very interestingly, the IFR was found to form char residue on the surface of CNTs/expanded EG aggregates to not only improve the compactness of the porous char layer but also promote thermal oxidation resistance of this char layer. Owing to the synergistic effect of the IFR with expanded EG and CNTs, the flame retardancy of PP/EG/CNTs/IFR composite foams was dramatically improved, including delayed the flame spread and completely inhibited the droplet phenomenon, and reached the level of flame retardant HF-1 in the standard level combustion test. Moreover, the PP/10EG/5CNTs/25IFR composite foams prepared by this work also presented excellent ablation resistance in the case of a large-scale flame. [Display omitted] • A new method for rapidly forming a 3D network porous char layer during combustion of PP composite foam was demonstrated. • The synergistic action of ternary IFR/EG/CNTs combination enhanced heat insulation of PP composite foam during combustion. • The formation of a complete porous char layer of the foam during combustion maintains its original shape. • The PP/EG/CNTs/IFR foam shows excellent flame retardancy and ablation resistance in both small / large-scale flame tests. [ABSTRACT FROM AUTHOR]

Abstract: A novel combined catalyst of fumed silica (SiO2) with Ni2O3 was demonstrated to be more efficient than SiO2 or Ni2O3 alone in enhancing the char yield of poly(lactic acid) (PLA) and improving its char layer structure, which greatly enhanced the flame retardancy of PLA. The results of field-emission scanning electron microscope, transmission electron microscope, X-ray diffraction, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy revealed that the residual chars mainly consisted of block-like carbon and carbon nanotubes with some surface functional groups. The flame retardancy of PLA and its composites was studied by cone calorimeter test. The heat release rate and total heat release of PLA composites containing both SiO2 and Ni2O3 decreased significantly in comparison with those of neat PLA. The investigation of the synergetic mechanism showed that in the presence of both SiO2 and Ni2O3, a large amount of chars were in situ formed from the catalytic carbonization of degradation products of PLA by Ni2O3 during combustion. This not only reduced the release of flammable degradation products, but also acted as an insulating barrier to prohibit the oxygen and feedback of heat from reaching the underlying substrate. On the other hand, the formation of a percolated network structure of SiO2 and Ni2O3 particles in PLA matrix increased the melt viscosity of PLA and facilitated the formation of a more compacted protective layer, which promoted the flame retardancy of PLA. [Copyright &y& Elsevier]

Abstract: A novel combined catalyst of activated carbon (AC) with Ni2O3 was demonstrated to be much more efficient than AC or Ni2O3 alone in enhancing the char yield of polypropylene (PP) and improving its char layer structure, which greatly improved the thermal stability and flame retardancy of PP. The results of X-ray diffraction, field-emission scanning electron microscope and transmission electron microscope revealed that the residual char mainly consisted of carbon nanotubes (CNTs). Thermal gravimetric analyses results indicated that the combination of AC and Ni2O3 dramatically enhanced the thermal stability of PP. The flame retardancy of PP and its composites was studied by cone calorimeter test. The heat release rate and total heat release of the ternary PP/7.5AC–7.5Ni2O3 composite decreased significantly in comparison with those of neat PP. The investigation of the synergetic mechanism showed that in the presence of both AC and Ni2O3, a large amount of CNTs were in situ formed from the degradation products of PP during combustion. This not only reduced the release of flammable degradation products of PP, but also acted as a thermal shield for energy feedback from the flame. In addition, the formation of a network-like structure of AC and Ni2O3 particles in PP matrix favored the formation of a more compacted protective layer, which enhanced the flame retardancy of PP. [Copyright &y& Elsevier]

Abstract: Polypropylene/carbon black (PP/CB) nanocomposites were prepared by melt compounding to investigate the effect of nanofiller loadings on the thermal and flammability properties of PP. The obtained nanocomposites displayed not only dramatically enhanced thermal stability both under nitrogen and in air, but also improved flame retardancy to some extent. Moreover, the higher the loading level of CB, the better was the improved effect. This enhanced mechanism was attributed mainly to trapping of peroxy radicals by CB nanoparticles at elevated temperature to form a gelled-ball crosslinked network, which act as a barrier to both heat and mass transfer. The thermal-oxidation cross-linking reaction was supported by the results of rheological properties, gel measurements and FTIR analysis. [Copyright &y& Elsevier]

Abstract: Molybdenum-phenolic resin (Mo-PR) was grafted onto the surface of multi-walled carbon nanotubes (MWCNTs) to obtain modified MWCNTs (CNT-PR). Compared to epoxy resin, epoxy resin/CNT-PR nanocomposites showed the improvements in flame retardancy and mechanical properties. Structural characterization showed that the grafted Mo-PR improved the dispersion of MWCNTs in epoxy resin and enhanced the interfacial interaction between CNT-PR and epoxy resin. On the other hand, the grafted Mo-PR could show high char yield during the process of combustion. Thus the flame retardancy of nanocomposites was improved, especially for the heat release rate and total smoke production. Furthermore, the combination of CNT-PR with melamine dramatically promoted the LOI value and the level of UL-94 rating. [Copyright &y& Elsevier]

Abstract: Two organoclays, octadecylammonium modified montmorillonite (COM) and an anionic surfactant modified montmorillonite (AOM), were used to prepare acrylonitrile–butadiene–styrene (ABS)/clay composites. The flammability of these composites was evaluated by cone calorimetry. COM enhanced the flame retardancy of ABS/COM composite due to the catalysis by acidic sites originating from COM. Interestingly, AOM presented a similar flame retardancy to ABS/AOM composite, although AOM did not form the acidic sites. The morphology observation showed that the dispersion degree of AOM in ABS resin was lower than that of COM, which was also confirmed by the rheological properties of ABS composites. The investigations on the surface of the residue after cone calorimeter tests showed that the better flame retardancy of ABS/AOM composite was mainly due to the special structure of AOM. [Copyright &y& Elsevier]

Abstract: Effects of organically modified montmorillonites (OMMTs) with different type and amount of modifiers on flame retardancy of polystyrene (PS) have been studied. The results from morphology analysis, gas chromatography–mass spectrometry and cone calorimeter have showed different mechanisms for the flame retardancy of PS/OMMTs composites, depending on surface property of OMMTs. One is the catalysis of acid sites formed on the surface of octadecylammonium modified MMT (c-MMT) via Hoffman decomposition on the carbonization of degradation products, which promotes the formation of clay-enriched char barrier. The other is related to chemical effect of inherent properties of MMT sheets on reactive intermediates during combustion, which work in PS/Na-MMT and PS/sodium dodecylsulfonate modified MMT (a-MMT) composites. Furthermore, the effect of the aggregate states of a-MMT on the flame retardancy of PS/a-MMT composites was studied. In the case of a-MMTs from spraying drying, a good protective layer with foam-like aggregate state of MMT sheet was formed in the residue, which results in low peak value of heat release rate of PS/a-MMT composites. [Copyright &y& Elsevier]

It is a great challenge to improve the flame retardancy of polymer materials by adding eco-friendly magnesium hydroxide (Mg(OH) 2) but simultaneously maintain satisfied mechanical performances. In this study, expanded graphite (EG) as a synergist was introduced into poly(butylene succinate) (PBS)/Mg(OH) 2 system to investigate the effect of EG on their flame retardancy, thermal stability and mechanical properties. The results showed that only addition of 5 wt% EG into PBS/20 wt%Mg(OH) 2 resulted in excellent flame retardancy, including that the LOI was 29.4%, the UL-94 rating reached to V 0 , and the PHRR decreased by 73%. These flame retarded parameters were comparable or even better than that of PBS/40 wt%Mg(OH) 2 composites. More importantly, PBS/20 Mg(OH) 2 /5 EG presented much better thermal stability and mechanical properties than PBS/40 wt%Mg(OH) 2 , indicating a balanced improvement on comprehensive performances of PBS. Based on the comparison with PBS/20 Mg(OH) 2 /5Graphene(Gr) system and the structure analysis for residual chars, the mechanism for improved flame retardancy was attributed to the formation of gradient-structured char layer due to the helpful thermal expansion process of EG together with the decomposition of Mg(OH) 2 during combustion, resulting in better barrier action to heat, oxygen and flammable gases via "labyrinth effect". As far as we know, it is the first report that gradient-structured char layer was discussed in flame retarded polymer systems. Hence, this work provides not only a high-efficient synergist to improve the flame retardant efficiency of Mg(OH) 2 , but also useful guidelines to design polymer composites with balanced comprehensive performances. A gradient-structured char layer formed in poly(butylene succinate)/magnesium hydroxide/expanded graphite (PBS/Mg(OH) 2 /EG) system during combustion, resulted in remarkably improved flame retardant efficiency of Mg(OH) 2 as well as a good balance on flame retardancy and mechanical properties. Image 1 [ABSTRACT FROM AUTHOR]