Flame-retardant behavior and protective layer effect of phosphazene-triazine bi-group flame retardant on polycarbonate

A series of flame-retardant polycarbonate (PC) composites with different ratios of phosphazene-triazine bi-group flame retardant (A3) were prepared. The flame retardant performance and thermal stability of PC/A3 composites were characterized by LOI, UL 94 vertical burning test, cone calorimetry test and TG. Results show that when the addition of A3 is 13.5%, the PC/A3 composite can pass UL94 V-0 level with a LOI value of 29.3% and reduce the peak heat release rate by 47.5% during the combustion. TG results show that adding 5% A3 can increase the initial decomposition temperature of the PC by 7°C in nitrogen and 9°C in air. Investigation of the morphology and chemical structure of char residue demonstrates that A3 promotes the formation of more complete and compact char residue which acts as physical barriers to inhibit the transfer of heat and oxygen, resulting the good flame retardant properties. The analysis of gaseous pyrolysis product reveals that A3 also exerts a flame-retardant effect in gas phase by releasing PO· free radicals.     

Preparation and properties of environmental friendly nonhalogen flame retardant melamine cyanurate/nylon 66 composites

Melamine cyanurate (MCA) was utilized as an environmental friendly additive to prepare the nonhalogen flame retardant MCA/Nylon 66 composites by melt blending technique. Because of the strong hydrogen bond interactions and fine interfacial compatibility between MCA and Nylon 66, the resultant even dispersion of MCA filler in polymer matrix leads to the better toughness and strength of MCA/Nylon 66 composites than those of neat Nylon 66. Both Nylon 66 and MCA/Nylon 66 composites exhibit similar α‐crystalline structure, but the presence of MCA influences the distribution of α1 and α2 crystalline phases in Nylon 66 by inducing its hydrogen‐bonded sheet separation. Moreover, the blending of MCA and Nylon 66 increases the crystallization temperature and exothermicity but decreases the thermal stability of Nylon 66 and accelerates the degradation of MCA. The MCA/Nylon 66 composites show better flame retardancy at intermediate MCA contents of 10 and 15 wt %. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Microencapsulation of APP‐I and influence of microencapsulated APP‐I on microstructure and flame retardancy of PP/APP‐I/PER composites

In this article, the microencapsulated ammonium polyphosphate crystalline with form I (APP‐I) coated with melamine‐formaldehyde (MF) was prepared by in situ polymerization. Results of Fourier transform infrared spectra (FTIR), thermogravimetry (TG) energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM) demonstrate that APP‐I is successfully microencapsulated with MF. Compared with APP‐I, the microencapsulated APP‐I with MF (MFAPP‐I) is of much smaller spheroidal particle size and lower solubility in water. In this study, the polypropylene (PP)/APP‐I/penpaerythritol (PER) and PP/MFAPP‐I/PER composites are prepared, and flame retardancy, thermal stability, and microstructure of corresponding composites are carefully investigated by limiting oxygen index (LOI), UL‐94 testing, TG, EDS, and SEM. Experimental results show that PP/MFAPP‐I/PER composites have advantages over PP/APP‐I/PER composites in terms of flame retardant properties and water resistance. Results of TG, SEM, and EDS show that the microencapsulated APP‐I with MF resin is conducive to increase the amount of residual yield and improve thermal stability of PP/MFAPP‐I/PER composites and the compatibility and dispersion of MFAPP‐I. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The flammability of expandable polystyrene foams coated with melamine modified urea formaldehyde resin

Urea formaldehyde resin (UF) was modified by introducing melamine during the condensation in order to reduce the amount of free formaldehyde and increase the solid content. The melamine modified UF (MUF) was firstly mixed with intumescent flame retardant (IFR) and then coated on the surface of pre‐expanded polystyrene (PS) particles to prepare flame retardant expandable PS (EPS) foams. The flammability of EPS foam samples was characterized by limiting oxygen index (LOI), UL‐94 vertical burning and cone calorimeter tests, and the results indicated that the peak heat release rate was significantly reduced from 406 to 49 kW/m² and LOI value could reach 36.3 with V‐0 rating in UL‐94 test after coated with IFR. The smoke density test indicated that the maximum smoke density was decreased by the addition of IFR. Thermal analysis suggested that the thermal stability and char formation were significantly improved by the presence of coated flame retardants. The residual char observation revealed that MUF and IFR were beneficial to form integrated char layers with hollow stents, which could be the main reason for the improvement of flame retardant properties. The mechanical properties of flame retardant EPS foams can still meet the standard requirements for industrial applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44423.     

Thermal and flammability performance of polypropylene composites containing melamine and melamine phosphate‐modified α‐type zirconium phosphates

In this article, melamine (MA) and melamine phosphate (MP) have been intercalated into α‐type zirconium phosphate (α‐ZrP) interlayer spaces. The structure and thermal properties of the corresponding powders, MA‐ZrP and MP‐ZrP, were ascertained by X‐ray diffraction, Fourier transform infrared spectra, X‐ray photoelectron spectroscopy measurement, and thermogravimetric analyses (TGA). Furthermore, polypropylene (PP) and its intumescent flame retardant (IFR) composites containing the two organically modified α‐ZrP powders using maleic anhydride‐grafted PP (JPP) as compatibilizer were fabricated by melt blending. The results from TGA and cone calorimetry demonstrated that PP/JPP and PP/JPP/IFR composites containing MA‐ZrP and MP‐ZrP exhibited better thermal stability and burning behavior in comparison with their corresponding counterparts, PP/JPP and PP/JPP/IFR, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40254.     

Flame retardance of montmorillonite/rubber composites

The effect of dispersion of clay in rubber on the mechanical properties and flame retardance of rubber/montmorillonite (MMT) nanocomposites and rubber/MMT microcomposites were investigated in the present article, and the results were compared with the performance of silica reinforced rubber composites. Cone calorimeter test and limiting oxygen index test were employed to evaluate the flame retardance. From the results, it could be seen that the rubber/MMT nanocomposites always possessed the best flame retardance, such as lower peak heat release rate and higher fire performance index value. In addition, the rubber/MMT nanocomposites also showed better mechanical properties than the pure rubber and the other composites, especially in tear strength. With the rubber/silica composites, as expected, the silica could appropriately endow the rubber with flame retardance. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synergistic effect of aluminum hydroxide and nanoclay on flame retardancy and mechanical properties of EPDM composites

The composites based on ethylene–propylene–diene monomer rubber (EPDM) with aluminum hydroxide (ATH), nanoclay, vulcanizing agent, and curing accelerator were prepared by conventional mill compounding method. The thermal stability and the flame retardant properties were evaluated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL‐94 test, cone calorimeter, and smoke density chamber tests. The results indicated that the substitution of the nanoclay in the EPDM/ATH composites increased the 50% weight loss temperature and the LOI value, and reduced the peak heat release rate (pk‐HRR), the extinction coefficient (Ext Coef), the maximal smoke density (Dm), and the whole smoke at the first 4 min (VOF4) of the test specimens. The synergistic flame retardancy of the nanoclay with ATH in EPDM matrix could imply that the formation of a reinforced char/nanoclay layer during combustion prevents the diffusion of the oxygen and the decomposed organic volatiles in the flame. The mechanical properties of the composites have been increased by replacing more of the nanoclays into the EPDM/ATH blends. The best loading of the nanoclay in EPDM/ATH composites is 3 wt %, which keeps LOI in the enough value, the V‐0 rating in the UL‐94 test, and the improved mechanical properties with better dispersion and exfoliation of the nanoclays shown by transmission electron microscopy (TEM) micrographs. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2042–2048, 2013     

Effect of borax on the thermal and mechanical properties of ethylene‐propylene‐diene terpolymer rubber‐based heat insulator

The effect of Borax on the mechanical and ablation properties of three different ethylene‐propylene‐diene terpolymer (EPDM) compounds containing 20 phr carbon fiber, 20 phr Kevlar or 10 phr/ 10 phr carbon fiber/ Kevlar was investigated. All formulations contained 30 phr fumed silica powder and 10 phr paraffinic oil. It was found that adding Borax to the composite samples containing carbon fiber or Kevlar fiber or their mixture with an equal ratio can increase the tensile strength, elastic modulus and hardness with a slightly decrease in the elongation at break of the rubber samples. The results of thermogravimetry analysis (TGA) on the various samples showed significant increase in the char yield at 670°C by adding Borax to the rubber compounds. Moreover, ablation resistance of samples was also improved by increasing Borax content. Meanwhile, density and thermal conductivity of the insulator were also reduced up to about 10% when the carbon fiber was replaced with the Borax. The results indicated that composites containing Kevlar have high storage modulus and produce compact and stable char. EPDM rubber composite containing Borax (20 phr), carbon fiber (10 phr), and Kevlar (10 phr) showed thermal and ablative properties comparable with those of the asbestos‐ filled EPDM. The thermal conductivity and ablation rate of the above‐ mentioned sample were 0.287 W/m/K and 0.13 mm/s respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41936.     

Flammability and thermal behaviors of polypropylene composite containing modified kaolinite

Exfoliatied kaolinite (E‐Kaol) was prepared by intercalating DMSO and KAc into kaolinite successively followed by irradiation under ultrasonic. The modified kaolinite was then introduced to polypropylene (PP) by melt blending in order to improve the fire performance of the composite. The flammability and thermal behaviors of PP composite were analyzed by limit oxygen index, vertical burning test, cone calorimeter test, and thermal‐gravimetric analysis, respectively. The microstructure of PP composites was characterized by Fourier‐transformed infrared spectroscopy, X‐ray diffraction, and scanning electron microscope (SEM). It was demonstrated the presence of only 1 phr E‐Kaol could improve the LOI values of PP/MCAPP/ATH composite from 26.4 to 28.0, and decrease the peak value of heat release rate and smoke production rate of the PP/MCAPP/ATH by 60.7% and 39.1%, respectively, compared with that of PP sample. Morphology analysis by SEM showed that E‐Kaol in PP composite was beneficial to forming rigid and compact char structure. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41761.     

Curing behavior,mechanical, and flame-retardant properties of epoxy-based composites filled by expandable graphite and ammonium polyphosphate

In this study, 4,4′-Diaminodiphenyl methane (DDM) was exploited as hardener for diglycidyl ether of daidzein (DGED) and epoxy resin mixture (E-D). The composites were produced by blending with different contents of ammonium polyphosphate (APP) and expandable graphite (EG) into E-D resin, named E-D/A-E composites. Firstly, E-D/A-E blends were analyzed by Fourier transform infrared spectroscopy and DSC to evaluate their curing behavior. The TGA was performed on the E-D/A-E composites to analyze their thermal stability, and the thermal properties of the composites were enhanced by adding APP-EG (A-E) flame retardants. The mechanical properties and the fractured surfaces of the E-D/A-E composites were studied by tensile, impact tests and scanning electron microscopy. Finally, through torch burning test, limiting oxygen index (LOI), vertical burning (UL-94) and micro-calorimetry tests, the influence of A-E flame retardants contents on flammability of composites were evaluated. The results showed that the UL-94 V-0 rating was obtained for the E-D/A-E composites and the composites exhibited a self-extinguishing phenomenon. When A-E flame retardants content reached 9.1 wt%, the LOI value reached 34.5%, and total heat release (Total HR) was reduced by 20.2% compared with E-D/A-E 1.     

Polydopamine modified ammonium polyphosphate modified shape memory water-borne epoxy composites with photo-responsive flame retardant property

Shape memory epoxy (SMEP) is a high performance shape memory polymer; however, is extremely flammable which severely restricts its applications. In this work, a novel polydopamine modified ammonium polyphosphate (PDA@APP) flame retardant was prepared to improve the flame retardant and enrich the response method of SMEP. Through flame retardancy test confirmed that the flame retarding properties of the PDA@APP/WEP composites significantly improved than the APP/WEP composites, the limiting oxygen index (LOI) values of the APP/SMEP and the PDA@APP/SMEP samples increased by 29.8% and 32.2%, respectively. Moreover, the PDA@APP/WEP composites had excellent light response shape-memory performance. Interestingly, the PDA@APP/WEP treated polyester fabric exhibited excellent light crease recovery performance and excellent flame retardant property. This work develops a new method for fabric crease recovery and will help broaden the application of WEP and its composites.     

Effect of particle size and content of magnesium hydroxide on flame retardant properties of asphalt

The flame‐retardant properties of asphalt for some building applications are very important. This article is mainly focused on the influence of particle size and content of magnesium hydroxide (MH) on the flame‐retardant properties of asphalt. The limit oxygen index and cone calorimeter results indicate that as the MH content and mesh number increase, the flame‐retardant properties of MH‐filled flame‐retardant asphalt show a rising trend. But the role of particle size in smoke suppression is not obvious. Several tests confirm that the dispersion of the MH have some influence on the flame‐retarding effect of asphalt. The 3000 mesh MH for the preparation of flame‐retardant asphalt shows optimal performance. The experimental data show that the softening point of flame‐retardant asphalt increases, but the ductility and penetration decrease with increasing MH content. MH affects the asphalt viscosity, but not affects the adhesion of the asphalt to gravel. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The effect of 3D structure design on fire behavior of polyethylene terephthalate glycol containing aluminum hypophosphite and melamine cyanurate

Effect of the shape of 3D printed samples on fire behavior of polyethylene terephthalate glycol (PET-G) and PET-G additivated with a mix of aluminum hypophosphite (AHP) and melamine cyanurate as flame retardant, was investigated. The additives improved fire performance (e.g., maximum average rate of heat emission, total oxygen consumption, heat release rate indices) irrespective of structural complexity, favoring carbonaceous char formation. However, at increasing structural complexity, they promoted higher release of smoke, compared to neat PET-G, because of a change in the prevalent retardation mechanism, which became dominated by the flame inhibition action of AHP. Consequently, the synergistic effect obtained combining the two additives, was hindered. Impact of product design on mechanisms of fire retardation helps in devising engineering solutions aimed at meeting required level of fire-safety performance, which should be tailored to the specific product.     

Study on flammability of montmorillonite/styrene‐butadiene rubber (SBR) nanocomposites

The flammability of montmorillonite (MMT)/SBR nanocomposites, prepared by the technique of cocoagulating rubber latex and clay aqueous suspension, was investigated. Flammability studies, performed on the cone calorimeter, showed that the maximum heat release rate (HRR) of SBR decreased from 1987 to 1442 kw/m² with the introduction of nanoclay (20 phr). This nanocomposite had the lowest mass loss rate and the largest amount of char upon combustion compared with conventional SBR composites with the same clay loading and pure SBR. The permeability properties of MMT/SBR composites were also measured. It was deduced that the lowered permeability was responsible for the reduced mass loss rate and hence the lower HRR. Unfortunately, the oxygen index (OI) of the nanocomposites was not as high as expected. Combination of Mg(OH)₂ and clay was effective for the improvement of both mechanical properties and OI. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 844–849, 2005     

Lightweight and flame retardant fluorosilicone rubber composited foam prepared by supercritical nitrogen

Improving the flame retardancy and lightweight of fluorosilicone rubber (FSR) foam is important for its application in aerospace, rail transportation, petrochemical equipment, etc. In this work, ammonium polyphosphate (APP) and expandable graphite (EG) were used as synergistic flame retardants, and the lightweight FSR composite foam with flame retardancy was prepared by supercritical N₂ foaming. When there were 12.5 phr APP and 7.5 phr EG, the composite foam with density of 0.254 g/cm³ showed superiority in foaming performance and flame retardancy, and the limit oxygen index was 36.4%, the UL-94 grade reached V-0, the ignition time was 12 s and the fire performance index was 0.071 s·m²/kW. In addition, the aging, oil and solvent resistance of FSR foam was not affected. This work provided data support for the production and application of the flame retardant FSR foam.     

Flame retardancy and mechanical properties of polyamide 6 with melamine polyphosphate and ionic liquid surfactant‐treated montmorillonite

The mechanical properties and inflammability of polyamide 6 (PA6) nanocomposites incorporated with Montmorillonite organoclay (MMT) modified with thermal stable ionic liquid surfactants were investigated. The compatibility between ionic liquid‐treated MMT and PA6 matrix was improved and the intercalation morphology was achieved, which resulted in the increaseof tensile modulus. However, the addition of organo‐MMTs alone did not improve the inflammability of the PA6 nanocomposite, because of strong melt‐dripping behavior of PA6 matrix. Addition of auxiliary melamine polyphosphate (MPP) intumescent flame retardant to the nanocomposite prevented the melt dripping and enhanced inflammability performance. The enhanced inflammability of PA6/organoclay/MPP nanocomposites was attributed to the synergistic effect between imidazolium or phosphonium organo‐MMTs and intumescent flame retardant MPP. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40648.     

Influence of gamma radiation on compatibilized LLDPE/magnesium hydroxide/sepiolite composites

The influence of gamma irradiation on the properties of compatibilized linear low‐density polyethylene/magnesium hydroxide (MH)/sepiolite composites has been investigated. Vinyl triethoxy silane and maleated polyethylene have been used as compatibilizers. The compatibilizing effect in the composites is confirmed by the Fourier transform infrared spectra, which showed the presence of additional chemical bonds, which are responsible for the enhanced polymer‐filler interaction. As a result, the miscibility of the polar additives into the nonpolar polymer matrix is enhanced. The scanning electron micrographs revealed that the additives are well embedded and uniformly dispersed in the polymer matrix without any voids. The known thermal decomposition temperature of MH (～ 350°C) is also increased in the compatibilized composites. In addition, 150 kGy irradiated composite showed a remarkable improvement of 37°C in the onset degradation temperature of unirradiated composite. Furthermore, the formation of radiation crosslinked structure in the composites also improved the mechanical properties of the composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and properties of nadic‐end‐capped cyclotriphosphazene‐containing polyimide/carbon fiber composites

New novel fire‐resistant and heat‐resistant cyclotriphosphazene‐containing polyimide resins were prepared in situ by the polymerization of (p‐aminophenoxy)(phenoxy)cyclotriphosphazenes with 3,3′,4,4′‐benzophenonetetracarboxylic acid or 3,3′,4,4′‐diphenylsulfonetetracarboxylic acid and a crosslink agent, 5‐norbornene‐2,3‐dicarboxylic acid and were used as polymer matrix compositing with a woven carbon fiber to prepare nadic‐end‐capped cyclotriphosphazene‐containing polyimide/carbon fiber composites. The thermal stability, flame retardance, morphology of the surface fracture, and some physical properties of the composites were investigated by thermogravimetric analysis, scanning electron microscopy, and a material testing system, respectively. The composites had good thermal stability, flame retardance, and mechanical properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 810–818, 2003     

The damping and flame‐retardant properties of poly(vinyl chloride)/chlorinated butyl rubber multilayered composites

The alternating multilayered damping composites, which were consisted of chlorinated butyl rubber (CIIR) layers and poly(vinyl chloride) (PVC) layers, were first prepared through multilayered coextrusion technology. The multilayered structure was controlled by adjusting the layer number or the thickness ratio of CIIR layer and PVC layer. The damping and flame‐retardant properties of the CIIR/PVC multilayered damping composites were investigated by dynamic mechanical analysis, the limiting oxygen index, and thermogravimetric analyzer, respectively. The results showed that the effective damping temperature range was broadened with increasing the layer number, since multilayered structure resulted in partial overlap of the loss peaks of CIIR and PVC. Meanwhile, the flame‐retardant properties of the multilayered composites were also enhanced with increasing the layer number. Less surface area of CIIR contacting oxygen in the confined burning space, rather than the formation of char residue, could effectively retard the combustion of the material. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41259.     

Influence of aging conditions on the mechanical properties and flame retardancy of HIPS composites

In this study, we evaluate the changes in physical properties and flame retardancy of HIPS composites after natural aging tests in Turpan (high sunlight radiation dose and dry) and Qionghai (high temperature and rainy) in China for 21 months. The HIPS composite aged in Turpan revealed a higher chromatic aberration than that in Qionghai due to the higher sunlight radiation dose. After aging tests for 21 months, the mechanical properties and the peak heat release of the HIPS composite aged in Qionghai decreased by more than 50% and increased by 39.7%, respectively, results that were worse than for the HIPS composite in aged Turpan. This was related to the combined effects of light, temperature, rain, and moisture in Qionghai leading to more severe degradation of HIPS composites, which results in breaking of the polymer chains and migration and erosion of the flame retardant. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46339.