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.     

Synergistic effect of aluminum hydroxide and expandable graphite on the flame retardancy of polyisocyanurate–polyurethane foams

For the first time, expandable graphite (EG) and aluminum hydroxide (ATH) was combined to improve the flame retardancy of polyisocyanurate–polyurethane (PIR–PUR) foam. The limited oxygen index increased from 26.5 for the PIR–PUR matrix to an incredible value of 92.8 when 24 phr (parts per 100 of matrix) EG and 60 phr ATH were incorporated into the matrix. Based on morphology observation and thermogravimetric analysis, it was speculated that two factors contributed to the improvement of flame retardancy primarily. First, ATH could effectively induce “villi” like particles, which was useful to form a dense char. The compact char layer could effectively impede the transport of bubbles and heat. Second, ATH and EG accelerated the initial degradation and fluffy char was quickly generated on the surface of the composites. Thus, the degradation of the composite was slowed down and the diffusion of volatile combustible fragments to flame zone was delayed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39936.     

Construction of thermoplastic cellulose esters matrix composites with enhanced flame retardancy and mechanical properties by embedding hydrophobic magnesium hydroxide

Biomass-based composites with renewability and biodegradability have attracted extensive researches, but their applications are hindered by poor mechanical properties and flame retardancy. Cellulose ester matrix composites (CEMC), a kind of biomass-based composites, were prepared with inorganic crystals as flame retardant and reinforcement. Cellulose acetate oleate (CAO) prepared by mechanical activation-assisted solid-phase reaction was used as thermoplastic matrix. Hydrophobic oleate-magnesium hydroxide (O-MH), which was surface-modified with oleic acid, was embedded into CAO to prepare O-MH/CAO composites by hot pressing. The introduction of oleoyl contributed to favorable thermoplasticity of cellulose ester, resulting in enhanced thermal stability and mechanical properties of CEMC. The uniform dispersion of O-MH in the CAO matrix via metal–organic coordination increased the mechanical properties and flame retardancy of O-MH/CAO composites, ascribing to the toughening effect and combustion inhibition effect induced by O-MH. This study provides a feasible technology for fabricating the CEMC with outstanding thermal stability and mechanical properties.     

Flame retardance and origin of bismaleimide resin composites with green and efficient aluminum phosphates

Developing green and high efficiency inorganic flame retardants is the trend of preparing flame retarding polymer composites. Aluminum phosphates (t‐hAP) with uniform, small dimension, and hexagonal structure were facilely synthesized, which have similar size (1–2 μm) but different structures from commercial spherical‐like aluminum phosphate (cAP). The flame retardance of bismaleimide (BD)/t‐hAP and BD/cAP composites were intensively investigated. t‐hAP is proved to have much better flame retarding effect than cAP, but also exhibits advantages over Mg(OH)₂ and Al(OH)₃. With only 5 wt % addition of t‐hAP into BD resin, the peak and total heat releases as well as total smoke production significantly reduce 42.3, 47.8, and 67.3%, respectively; besides, better data are obtained as the loading of t‐hAP increases to 10 wt %. These attractive data result from three effects induced by t‐hAP. Besides the better protection role of sheet structure, the strong hydrogen bonding between t‐hAP and BD resin endows the composite with good dispersion of t‐hAP and high crosslinking density; moreover, t‐hAP releases H₂O and NH₃, diluting flammable gases during combustion. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41089.     

The flame retardancy and mechanical properties of jute/polypropylene composites enhanced by ammonium polyphosphate/polypropylene powder

Surface flame retarded jute/polypropylene composites (J/P/A) were prepared via a modified strategy: the mixture of PP and APP powder was spread over the surface of jute/PP nonwoven felts, and then transformed into the flame retarded layer by the hot pressing process. The flame retardancy and thermal properties of composites were analyzed by limit oxygen index (LOI), horizontal burning rate (HBR), thermogravimetric analyses (TGA), and differential scanning calorimetry (DSC). We demonstrated that the flame retardancy and mechanical properties of composites was significantly improved compared with those obtained by presoaking the nonwoven fiber felts in flame retardant (FR) solvent before hot pressing. The mechanism of thermal degradation of jute fiber and flame‐retardant mechanism of composites were analyzed by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and scanning electron microscope (SEM). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43889.     

Mechanical properties and flame retardancy of PLA composites containing zinc oxide and chain extender

A micro-cross-linked structure had been constructed by the addition of zinc oxide with nanometer-scale particle size (nano ZnO) and chain extender (ADR) into intumescent flame retardant poly (lactic acid) (FRPLA). Flame retardant properties, mechanical properties and thermal stabilities were studied. Limited oxygen index of the FRPLA composite with 1% nano ZnO and 0.8% ADR (FRPLA/0.8ADR/1ZnO) was a maximum (39.4%). T_max and residue at 800°C of FRPLA/0.8ADR/1ZnO was the highest in air. Tensile strength, elongation at break and impact strength of FRPLA/0.8ADR/1ZnO was significantly higher than that which resulted with the addition of either individual filler, indicating that the synergistic effect between nano ZnO and ADR regulated the comprehensive performance of FRPLA. The synergetic effect between nano ZnO and ADR were further illustrated.     

Effect of particle size on flame retardancy and mechanical properties of hydroxyethyl diphosphate modified aluminum hydroxide intrinsic polyethylene terephthalate

Organic–inorganic hybrid flame retardant was obtained by modifying aluminum hydroxide with different particle size with 1-hydroxyethylidene-1,1-diphosphonic acid. The structure of the organic–inorganic hybrid flame retardant is characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy, while ¹H-NMR spectroscopy only characterizes specific samples. The thermal stability and flame retardancy of the samples were analyzed by thermogravimetric analysis, limiting oxygen index (LOI), vertical combustion of UL-94 and cone calorimeter. The results show that the modified 10 μm aluminum hydroxide has a better effect than the 25 μm aluminum hydroxide and 100 nm aluminum hydroxide. Compared with pure polyethylene terephthalate (PET), the LOI value of the best sample is increased by 24.4%, and UL-94 V reaches V-0 level. Heat release rate, total heat release rate, and carbon monoxide production rate decreased by 45.8%, 33.2%, and 41.5%, respectively, compared to pure PET. The results showed that the aluminum hydroxide with a particle size of 10 μm exhibited the best flame retardant effect, which could be attributed to the decomposition of organic phosphoric acid and the dehydration of aluminum hydroxide, yielding a higher amount of residual carbon.     

Boosting flame retardancy of thermoplastic polyurethane: Synergistic effect of nickel phosphide nanoparticles and molybdenum disulfide nanosheets

For the first time, a novel nanohybrid based on nickel phosphide (Ni₂P) nanoparticles and molybdenum disulfide (MoS₂) nanosheets was facilely synthesized for enhancing flame retardancy and smoke suppression of thermoplastic polyurethane (TPU). The synergistic effect on flame retardancy is proposed. TPU composite with 2 wt% Ni₂P/MoS₂ hybrid exhibits the best overall flame retardancy, while TPU composites with the same amount of individual Ni₂P nanoparticles and MoS₂ nanosheets are average in performance. Specifically, the 41.2% reduction of peak heat release rate (PHRR) is achieved for TPU/Ni₂P/MoS₂ composite, which is only 16.8% and 26.4% for TPU/Ni₂P and TPU/MoS₂ composites, respectively. In addition, a more intact protective char layer of TPU/Ni₂P/MoS₂ composite can be observed. These results clearly suggest the synergistic effect between Ni₂P nanoparticles and MoS₂ nanosheets. It is hypothesized that physical barrier effect and chemical catalytic ability of Ni₂P/MoS₂ hybrid contribute to the dramatic reduction of heat release and smoke production. The strategy proposed here is a simple yet efficient approach to fabricate high-performance MoS₂-based flame retardants.     

卡拉胶-纳米氢氧化铝协同阻燃天然橡胶

将BaCl2分级的k型卡拉胶(KC)和纳米氢氧化铝〔Al(OH)3〕构成的协同阻燃体系添加到天然橡胶(NR)中制备KC-Al(OH)3/NR复合材料。通过TG、极限氧指数(LOI)、锥形量热(CCT)以及SEM考察了不同质量比的KC和Al(OH)3对复合材料力学性能和阻燃性能的影响。结果表明,当KC与Al(OH)3以1∶1的质量比加入到NR时,KC-Al(OH)3/NR复合材料的热稳定性、阻燃性能最优,复合材料的LOI达到25%。与纯天然橡胶相比,复合材料总热释放量(THR)、热释放速率峰值(pHRR)、总烟释放量(TSP)和平均质量损失率(AMLR)分别降低了12%、65%、23%和62%。相比于单独添加Al(OH)3体系,复合材料拉伸强度和断裂伸长率分别增加了11%和17%。     

Facile preparation of attapulgite-based aerogels with excellent flame retardancy and better thermal insulation properties

A novel and environmentally friendly attapulgite-based aerogel with a three-dimensional fibrillary network structure was prepared by incorporation of nanometer-sized natural clay crystals, in this case attapulgite (ATP), into degradable poly(vinyl alcohol) (PVA), cotton cellulose nanowhisker, and melamine using only a simple blending method and subsequently a freeze-drying process. The ATP-based aerogel exhibits an abundant porosity with an average mesopore size of 8.0 nm in diameter. Compared to fragile and rigid inorganic aerogels, the as-prepared aerogel shows good flexibility and mechanical strength with a compressive strength of 9.65 × 10⁴ Pa and 10.19 × 10⁴ Pa at 20% and 40% of compressive strain, respectively. The limiting oxygen index (LOI) and vertical flame tests show that the resulting aerogel possesses excellent flame retardancy, with an LOI of 59.5%. Microcalorimetry test results show that the total heat release of the aerogel is as low as 5.1 KJ/g. Also, the sample shows a better thermal insulation property, with a thermal conductivity of about 0.045 W m⁻¹ K⁻¹ in air. Taking advantage of a simple and environmentally friendly fabrication, abundant natural clay resources, easy scalability, nearly no pollution emission in the process, and cost-efficient production, the ATP-based aerogel has great potential as ideal flame retardant and thermal insulation materials for many applications such as modern building construction or energy-efficient coatings. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47849.     

Synergistic effect of expandable graphite and α‐type zirconium phosphate on flame retardancy of polyurethane elastomer

Organically modified zirconium phosphate (OZrP) was prepared by cation exchange of natural counterions with hexadecyltri‐n‐butylphosphonium bromide. Subsequently, OZrP and expandable graphite (EG) were incorporated into polyurethane elastomer (PUE), and the thermal stability and flame retardancy of PUE composites were investigated. The thermogravimetric analysis indicated that partial substitution of EG with OZrP could improve both the thermal stability and char yield of PUE composites. The cone calorimetry and limiting oxygen index test showed that partial substitution of EG with OZrP could further enhance the flame retardancy of PUE composites and presented an excellent synergistic effect. Moreover, the char residue of PUE composites was analyzed by X‐ray photoelectron spectroscopy and laser Raman spectroscopy. Their results indicated that the synergistic effect of the physical barrier to prevent transmission of heat and mass between condensed and gas phases. Therefore, the further combustion of the nether material could be inhibited, which created better flame retardancy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45188.     

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     

Flame retardancy and mechanical properties of EVA nanocomposites based on magnesium hydroxide nanoparticles/microcapsulated red phosphorus

The flame retardancy and mechanical properties of ethylene vinyl acetate (EVA) polymer nanocomposite based on magnesium hydroxide (MH) nanoparticles with lamellar‐shape morphological structures and synergistic agent microcapsulated red phosphorus (MRP) have been studied by limiting oxygen index (LOI), cone calorimeter test (CCT), UL‐94 test, tensile strength (TS), and elongation at break (EB). Results showed that LOI values of lamellar‐like nanosized MH (50 × 350 nm²) samples were 1–7 vol. % higher than those of the common micrometer grade MH (1–2 μm) in all additive levels. When 1–3 phr MRP substituted for nanosized MH filler, LOI value increased greatly from original 37 to 55, and met the V‐0 rating in the UL‐94 test. The values of TS for MH nanoparticles composites increased from 10.4 to 17.0 MPa as additive loading levels increased from 80 to 150 phr, respectively, while the corresponding values for common micrometer MH composites decreased steadily from 9.7 to 7.1 MPa. Thermogravimetric analysis (TGA) and dynamic Fourier‐transform infrared spectroscopy (FTIR) results revealed two‐step flame‐retardant mechanism. First, MH particles decompose endothermically with the release of 30.1% hydration water in the 320–370°C temperature range. Second, MRP promote the formation of compact charred layers slowly in the condensed phase in the 450–550°C temperature range. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

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.     

Synergistic effect of expandable graphite and aluminum hypophosphite on flame‐retardant properties of rigid polyurethane foam

A series of flame retarding rigid polyurethane foam (RPUF) composites based on expandable graphite (EG) and aluminum hypophosphite (AHP) were prepared by the one‐pot method. The properties were characterized by limiting oxygen index (LOI) test, cone calorimeter test, thermogravimetric analysis (TGA), real‐time Fourier transform‐infrared spectra (RT‐FT‐IR), X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), etc. The results indicate that both EG and AHP could enhance the flame retardency of RPUF composites. Besides, the flame retardant effect of EG was better than that of AHP. The results also show that partial substitution of EG with AHP could improve the flame retardency of RPUF, and EG and AHP presented an excellent synergistic effect on flame retardancy. What is more, compared with RPUF/20EG and RPUF/20AHP, the heat release rate (HRR) and total heat release (THR) of RPUF/15EG/5AHP were lower.TGA results indicate that partial substitution of EG with AHP could improve the char residue which provided better flame retardancy for RPUF composites. The thermal degradation process of RPUF composites and the chemical component of the char residue were investigated by RT‐FT‐IR and XPS. And the results prove that RPUF/15EG/5AHP had higher heat resistance in the later stage. Compared with the RPUF composites filled with EG, a better cell structure and mechanical properties were observed with the substitution of AHP for part of EG. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42842.     

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.     

Facile preparation and flame retardancy mechanism of cyclophosphazene derivatives for highly flame-retardant silicone rubber composites

A novel and efficient flame retardant cyclophosphazene derivative Hexa (p-acetamidophenoxy) cyclotriphosphazene (HACP) was successfully prepared via a facile one-step reaction. The chemical structure of HACP was characterized and confirmed by FT-IR, ¹H and ¹³C NMR. Then the as-prepared HACP was incorporated into addition-cure liquid silicone rubber (ALSR) matrix to prepare highly flame-retardant rubber composites. It was found that the incorporation of HACP can significantly enhance the flame resistance of ALSR. Typically, the ALSR composites filled with 30 phr HACP achieved UL-94 V-0 rating and meanwhile the total heat release and total smoke release were decreased by 26.9% and 41.5%, respectively. Moreover, the flame-retardant mechanism of ALSR/HACP composites was investigated by TGA, Py-GCMS, FT-IR, SEM and EDX, confirming that HACP plays a significant role in capturing free-radicals and forming protective layers. This work designed a novel cyclophosphazene-based flame retardant to significantly enhance the flame retardancy of ALSR, which may offer some valuable inspiration for the fabrication of highly flame-retardant polymer composites.     

Flame retardancy and thermal and mechanical performance of intercalated,layered double hydroxide composites of polyamide 11, aluminum phosphinate,and sulfamic acid

Sulfamic acid‐intercalated MgAl‐layered double hydroxide (SA‐LDH) was prepared and added with aluminum phosphinate (AlPi) into polyamide 11 (PA11). The results showed that AlPi/SA‐LDH made a positive contribution to both flame retardancy and thermostability, and the effect was demonstrated with the limiting oxygen index (LOI), vertical burning tests (UL‐94), cone calorimetry (CONE), and thermogravimetric analysis (TGA). The char morphologies were observed by SEM, and its chemical composition was investigated by Fourier transform infrared spectroscopy (FTIR). The decomposition mechanism was examined by TGA‐FTIR. The results showed that the LOI of PA11 was only 23.0 and cannot pass any UL‐94 rating. The addition of 20% AlPi increased the LOI to 31.5 and passed the UL‐94 V‐1 rating, and AlPi/SA‐LDH 15%/5% increased the LOI to 32.4 and also passed the UL‐94 V‐1 rating. The CONE results revealed that 20% of either AlPi or AlPi/SA‐LDH brought about a 30% decrease in the peak heat release rate (pHRR). The contribution of SA‐LDH to flame behavior was especially reflected in the postponement of pHRR. SEM showed that the char morphologies became denser after SA‐LDH incorporation. The improvement in thermal stability of the AlPi/SA‐LDH combination was documented by TGA in both N₂ and air atmospheres. The mechanical performance deterioration caused by AlPi was partly improved by SA‐LDH. The storage modulus (E′) below the T_g of AlPi/SA‐LDH 15%/5% was about 300 MPa higher than with 20% AlPi. This was attributed to a compatibility improvement. The interaction forces among PA11, AlPi, and SA‐LDH were probed by X‐ray photoelectron spectrometry. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43370.     

Improvement of flame retardancy in phenolics and paper-sludge/phenolic composites

Paper-sludge/phenolic composites were fabricated using a novolac-type phenolic resin and paper sludge. A phosphate flame retardant containing halogen (tris 2-chloroethyl phosphate) and inorganic flame retardant (aluminum trihydroxide) were introduced into neat phenolics and paper-sludge/phenolic composite in order to improve their flame retardancy. In addition, magnesium hydroxide and halogenated flame retardant were added into the paper-sludge/phenolic composite. The flame retardancies were estimated with the UL 94 test. To study the flame retardant mechanism, thermal analysis of the phenolics and the paper-sludge/phenolic composites were carried out using a thermogravimetric analyzer and a differential scanning calorimeter. The phosphated flame retardant and inorganic flame retardant both showed the flame retardant effect on the phenolics. However, the flame retardancy of the paper-sludge/phenolic composite was enhanced only by phosphated and halogenated flame retardants. This result is attributed to the fact that the flame retardancies of the phenolics and paper-sludge/phenolic composite depend on their heat capacities and decomposition behaviors. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2043–2050, 1998     

Influence of fumed silica on the flame‐retardant properties of ethylene vinyl acetate/aluminum hydroxide composites

The flammability and synergistic flame‐retardant effects of fumed silica (SiO₂) in ethylene vinyl acetate (EVA)/aluminum hydroxide (ATH) blends were studied with limiting oxygen index measurements, UL 94 testing, cone calorimeter testing (CONE), and thermogravimetric analysis (TGA). The results show that the addition of a given amount of fumed SiO₂ can apparently improve UL 94 rating. The CONE data indicated that the addition of fumed SiO₂ greatly reduced the heat release rate. The TGA data showed that this synergistic flame‐retardant mechanism of fumed SiO₂ in the EVA/ATH materials was mainly due to the physical process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011