Peak Heat Release Research Articles

A COMPARATIVE THERMAL ANALYSIS OF FIRE-OFF TREATED COTTON, POLYESTER AND CO/PET FABRICS

The present paper analyzes the potential for commercially available flame-retardant chemical called Fire-off for enhancing the flame-retardant properties of polyester (PET) and cotton (Co) fabrics and their corresponding blends (Co/PET). Fire-off was applied to the fabric through impregnation method and the resulting properties of these fabrics were assessed in terms of combustion behavior by use of a micro cone calorimeter (MCC) and Thermogravimetric Analysis (TGA). TGA results revealed that Fire-off could greatly enhance char residues of cotton, polyester and Co/PET fabrics at high temperature region. MCC results showed that Fire-off treatment could significantly decrease the heat release capacity (HRC), heat release rate (HRR), total heat release rate (THR) and peak heat release rate (pHRR) of cotton, polyester and Co/PET fabrics. According to comparison results, a near-perfect agreement between MCC and TGA data were found in terms of degradation temperatures and mass loss rates of fabric samples.

Shrinkage crack inhibiting of cast in situ tunnel concrete by double regulation on temperature and deformation of concrete at early age

The temperature difference between peak temperature due to the hydration of concrete and its surrounding is the key factor that leads to early age cracking in main structure of tunnel concrete, and autogenous shrinkage will increase the crack risk. Given this, a temperature rise inhibited and slight expansion mixture (HME) was adopted in a large scale cast in situ tunnel under water. Results indicate that HME decreased the hydration rate of cement in the acceleration period and prolonged the main heat release peak. The early age rate of adiabatic temperature rise was decreased with a negligible level effect on the final value after using HME. In this case, the peak temperature could be decreased under a certain heat dissipation condition. Meanwhile, HME could reduce shrinkage deformation not only in the temperature rise stage but also in the entire process. The reduction of compressive strength affected by using HME instead of cement and its regulation on cement hydration could be further reduced to a negligible level at later ages. The first sidewall and roof have been casted more than five months and no penetrating crack and leakage were observed, which means that the double regulation on temperature and deformation technology provides a feasible and effective approach to prevent the penetrating crack of cast in situ tunnel concrete at early age.

A novel intumescent flame retardant imparts high flame retardancy to epoxy resin

Intumescent flame retardant (IFR) has received the considerable attention ascribed to the inherent advantages including non‐halogen, low toxicity, low smoke release and environmentally friendly. In this work, a novel charring agent poly (piperazine phenylaminophosphamide) named as PPTA was successfully synthesized and characterized by Fourier transform infrared spectra (FTIR) and X‐ray photoelectron spectroscopy (XPS). Then, a series of flame‐retardant EP samples were prepared by blending with ammonium polyphosphate (APP) and PPTA. Combustion tests include oxygen Index (LOI), vertical Burning Test (UL‐94) and cone calorimeter testing，these test results showed that PPTA greatly enhances the flame retardancy of EP/APP. According to detailed results, EP containing 10 wt% APP had a LOI value of 30.2%，but had no enhancement on UL‐94 rating. However, after both 7.5 wt% APP and 2.5 wt% PPTA were added, EP‐7 passed UL‐94 V‐0 rating with a LOI value of 33.0%. Moreover, the peak heat release rate (PHRR) and peak of smoke product rate (PSPR) of EP‐7 were greatly decreased. Meanwhile, the flame‐retardant mechanism of EP‐7 was investigated by scanning electron microscopy (SEM), thermogravimetric analysis/infrared spectrometry (TG‐IR) and X‐ray photoelectron spectroscopy (XPS). The corresponding results presented PPTA significantly increased the density of char layer, resulting in the good flame retardancy.

Halogen free flame retardant finishing of wool and wool rich fabrics for aircraft seats

Wool and wool/nylon blended yarns were knitted and treated by a phosphorus sulphur based agent by padding. The flammability hazard was evaluated considering parameters such as; the spread of flame, heat release and smoke emission. The flame spread of fabrics was measured according to the FAR/CS 25.853 12 Second Vertical Bunsen Burner test procedure. Regardless of the blend ratio, the fabrics treated by the flame retardant (90% add-on) could comply with the vertical flammability requirements for aircraft materials. Important flammability parameters such as heat release rate and peak heat release rate ware measured by the cone calorimeter. The FR treatment of fabrics was found to be effective in reducing heat release and thus risks associated with fire. The smoke generated by the materials during flaming combustion was evaluated by both cone calorimeter and NBS smoke density chamber.

Biomass Chitosan-Induced Fe3O4 Functionalized Halloysite Nanotube Composites: Preparation, Characterization and Flame-Retardant Performance

An inorganic–organic nanohybrid flame retardant, HNT@CS@Fe3O4, is prepared by Halloysite nanotubes (HNT) as nanotemplate, chitosan (CS) as char-forming agent and ferroferric oxide (Fe3O[Formula: see text] playing in a catalytic role, aiming to endow enhanced flame-retardant performance of its nanohybrid. Results show that HNT@CS@Fe3O4 nanohybrids have a corn-like structure and can significantly improve the flame retardancy and thermal stability of epoxy resin (EP). Especially, the initial thermal degradation temperature of EP/HNT@CS@Fe3O4 is significantly improved by [Formula: see text]C relative to pure EP, and the residual carbon yield under air atmosphere is 8.8[Formula: see text]wt.%, which is significantly higher than other EP composites, indicating a higher thermal stability is offered by the as-prepared nanohybrid. The limiting oxygen index of EP/10HNT@CS@Fe3O4 is 31.3%, which is 10.2% higher than that of pure EP. Meanwhile, the HNT@CS@Fe3O4 nanofiller reduces the peak heat release rate, CO production and peak smoke production release of EP nanocomposite by 32.0%, 44.0% and 33.0% in a cone calorimeter test, respectively. This is because the HNT-based composite can form a three-dimensional network structure into the EP matrix to inhibit heat release and diffusion of flammable moieties upon burning of EP. In the meantime, the incorporated Fe3O4 nanoparticle can in situ catalyze the charring of CS and EP matrix on the surface of HNT during the combustion process, which also contributes to the significantly increased fire safety of EP.

Synergistic Effects of Two-Dimensional MXene and Ammonium Polyphosphate on Enhancing the Fire Safety of Polyvinyl Alcohol Composite Aerogels.

Fire and smoke suppressions of polyvinyl alcohol (PVA) aerogels are urgently required due to the serious fire hazard they present. MXene, a 2D transition-metal carbide with many excellent properties, is considered a promising synergist for providing excellent flame retardant performance. PVA/ammonium polyphosphate (APP)/transition metal carbide (MXene) composite aerogels were prepared via the freeze-drying method to enhance the flame retardancy. Thermogravimetric analysis, limiting oxygen index, vertical burning, and cone calorimeter tests were executed to investigate the thermal stability and flame retardancy of PVA/APP/MXene (PAM) composite aerogels. The results demonstrated that MXene boosted the flame retardancy of PVA-APP, and that PAM-2 (with 2.0 wt% MXene loading) passed the V-0 rating, and reached a maximum LOI value of 42%; Moreover, MXene endowed the PVA-APP system with excellent fire and smoke suppression performance, as the the peak heat release rate and peak smoke production rate were significantly reduced by 55% and 74% at 1.0 wt% MXene loading. The flame retardant mechanism was systematically studied, MXene facilitated the generation of compact intumescent residues via ita catalyst effects, thus further restraining the release of heat and smoke. This work provides a simple route to improve the flame retardancy of PVA aerogels via the synergistic effect of MXene and APP.

Highly Effective Flame-Retardant Rigid Polyurethane Foams: Fabrication and Applications in Inhibition of Coal Combustion.

The extemporaneous combustion of coal remains a major threat to safety in coal mines because such fire accidents result in casualties and significant property loss, as well as serious environmental pollution. This work proposed the fabrication of flame-retardant rigid polyurethane foam (RPUF) containing expandable graphite as char expander/sealant with melamine phosphosphate and 2-carboxyethyl (phenyl)phosphinic acid as char inducer and radical trapping agents. The as-prepared RPUF successfully inhibited coal combustion by forming thermally stable high graphitic content expandable intumescent char sealing over the coal. The RPUF achieved UL-94 V-0 rating in addition to significant reductions in peak heat release, total heat release, and CO and CO2 yields. The external and the internal residual char structure was studied by X-ray photoelectron spectra, Raman spectroscopy, and real-time Fourier transform infrared spectra techniques, and a flame-retardant mode of action has been proposed. This work provides important insight into a facile fabrication of highly efficient and economical flame-retardant RPUF to inhibit the spontaneous combustion of coal.

Synthesis of K-Carrageenan Flame-Retardant Microspheres and Its Application for Waterborne Epoxy Resin with Functionalized Graphene.

In this article, the intumescent flame-retardant microsphere (KC-IFR) was prepared by inverse emulsion polymerizations, with the use of k-carrageenan (KC) as carbon source, ammonium polyphosphate (APP) as acid source, and melamine (MEL) as gas source. Meanwhile, benzoic acid functionalized graphene (BFG) was synthetized as a synergist. A “four-source flame-retardant system” (KC-IFR/BFG) was constructed with KC-IFR and BFG. KC-IFR/BFG was blended with waterborne epoxy resin (EP) to prepare flame-retardant coatings. The effects of different ratios of KC-IFR and BFG on the flame-retardant properties of EP were investigated. The results showed that the limiting oxygen index (LOI) values increased from 19.7% for the waterborne epoxy resin to 28.7% for the EP1 with 20 wt% KC-IFR. The addition of BFG further improved the LOI values of the composites. The LOI value reached 29.8% for the EP5 sample with 18 wt% KC-IFR and 2 wt% BFG and meanwhile, UL-94 test reached the V-0 level. In addition, the peak heat release (pHRR) and smoke release rate (SPR) of EP5 decreased by 63.5% and 65.4% comparing with EP0, respectively. This indicated the good flame-retardant and smoke suppression property of EP composites coating.

Effect of Nano Filler on the Flammability of Bio-Based RPUF

In this study, CaCO3 nanostructures have been used to enhance the flame retardancy of vegetable oil based rigid polyurethane foams (RPUF). RPUFs were prepared by using polyol derived from transesterification reaction of castor oil. Prepared foams were characterized by cone calorimeter for their fire behavior. Results showed decrease in peak of heat release (PHRR) by the incorporation of nano calcium carbonate. Additionally, total heat release (THR), smoke production rate (SPR) and total smoke release (TSR) were also found to decrease remarkably. So, CaCO3 nanostructures have great potential as an additive to enhance flame retardant properties in vegetable oil based RPUF.

Optimisation of nozzle geometry in the modified common rail direct injection biodiesel-fuelled diesel engine

The study of the experimental work focused on the optimisation nozzle geometry in the modified common rail direct injection (CRDI) diesel engine powered with palm oil methyl ester (POME) fuel. The CRDI diesel engine modified in terms of the toroidal re-entrant combustion chamber (TRCC) shape and nozzle geometry. The experiments are conducted with POME and diesel fuels (DF) at 80% and 100% loads, respectively. The parameters, such as compression ratio (CR) 17.5, speed 1500 RPM, fuel injection timing (IT) 10° BTDC and 900 bar injection opening pressure (IOP), are maintained constant. The selected fuel IT and IOP were optimised in our previous research. The experiments results revealed that the 7-hole nozzle injector improved in break thermal efficiency (BTE) by 1.5% and 1.3% for diesel and POME, respectively, as compared to the 6-hole injector. The average percentages of emissions are reduced up to 7.24% and 7.81% for diesel and POME fuels, respectively, except oxides of nitrogen (NOx). The peak pressure (PP) and heat release rate (HRR) are improved by 2.40% and 3.65%, respectively, for DF. The similar increased trend of PP and HRR is 2.53% and 4.10%, respectively, for POME in the modified CRDI diesel engine.

Effect of Temperature and Accelerator on Gel Time and Compressive Strength of Resin Anchoring Agent

In this study, we examined the effects of different temperatures and accelerators on the gelation (gel) time and compressive strength of a Polyethylene Terephthalate (PET)-type unsaturated polyester resin anchorage agent. First, the formation temperature of 20–70°C was simulated using self-made test equipment. N,N-Dimethylaniline (DMA), N,N-dimethylp-toluidine (DMT), and hydroquinone were selected as accelerators to determine gel time and heat release peak. The gel time of an anchorage agent is strongly influenced by accelerant and temperature. When DMT, DMA, and hydroquinone were added at the same temperature, the gelation time increased; with increasing ambient temperature, the gelation time of the anchorage agent decreased. The peak exothermic value of the curing reaction was less affected by the accelerator, and the peak exothermic value of the anchoring agent increased with the increase in ambient temperature. Then, the compressive strength of the anchorage agent, maintained at 20, 50, and 80°C for 1.5, 6, 12, and 24 h, was measured. We found that the compressive strength of resin anchorage agent decreased significantly with the increase in temperature, and the addition of DMT can improve the compressive strength of resin anchorage agent slightly at the same temperature conditions. Finally, through Fourier transform infrared scanning analysis, we determined the intrinsic causes of the influence of temperature and accelerator on the gelation time and compressive strength of the anchorage agent. Through SPSS fitting analysis, an empirical formula for predicting gelation time based on ambient temperature is proposed. Our findings provide a basis for reasonable mixing time and support design optimization of anchorage support in deep stratum in high-temperature geothermal environments.

A Study on Performance of Common Rail Direct Injection Engine with Multiple-Injection Strategies

Diesel engines are robust and reliable besides their good fuel economy. However, these engines produce higher exhaust emissions with fossil diesel and further these emissions level increases when operated on biodiesels. A common rail direct injection (CRDi) engine shows higher brake thermal efficiency (BTE) and lower emissions as compared to compression ignition mode (CI mode) of engine operation. This research paper revealed the results of diesel engine operated in CRDi mode with single injection (SI) and multi-injections (MI) of fuel using diesel and biodiesel of honne oil at 80% load. The CRDi engine operation with both SI and MI showed higher BTE and lower emissions as compared to CI mode. The peak pressure and heat release rate of a CRDi engine operation were lower as compared to CI mode. Overall, it could be concluded that biodiesel-powered CRDi engine with double injection and triple injection could reduce oxides of nitrogen (NOx) emissions by 40.8% and 50%, respectively, while smoke emission by 10% and 16.6%, respectively. However, there was a little penalty on BTE and brake-specific fuel consumption.

The oxidation of C2-C4 diols and diol/TPGME blends in a motored engine

Inspired by the announcement that liquid biofuel will be used nationally by 2020 in China, the autoignition of surrogates from hydrogenated biomass pyrolysis oil, namely, the C2-C4 diols, including ethanediol, 1,2-propanediol, and 1,2-butanediol has been studied using a modified CFR engine. From the oxidation process before critical compression ratio (CCR), it is observed that C2-C4 diols had similar oxidation reactivity as ethanol, indicating that C2-C4 diols had the potential for use as a supplement for ethanol. In addition, both of ethanol and C2-C4 diols did not display low temperature heat release. The ignition characteristics of C2-C4 diols suggest that diol/TPGME blends could be used, as TPGME has high ignition quality and could be generated from diols with a carbon selectivity as high as 75%. Based on this idea, diol/TPGME blends with volume ratio 20:80 were prepared and tested using the modified CFR engine. The blends showed strong low temperature oxidation behavior, even under a low intake temperature at 120 °C and a low compression ratio at 4, the low temperature heat release peak could still be found for the blends. Finally, the physical delay and chemical delay times were tested by a modified CID instrument between 540 and 640 °C, indicating that chemical process played a more important role on the combustion process than physical process, and the influence of temperature was more important for physical processes than chemical processes.

Investigation of nickel ammonia phosphate with different morphologies as a new high-efficiency flame retardant for epoxy resin

Nanowires, nanosheets, and microflowers of nickel ammonium phosphate (NiNH4PO4·H2O) were synthesized by a mixed solvothermal method and used to improve the flame retardancy of epoxy resin (EP). The solvent concentration and surfactant content were found to play a key role in nucleation and growth of NiNH4PO4·H2O. The structure of NiNH4PO4·H2O was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The flame retardancy, thermostability, mechanical properties, and flame retardancy mechanism of EP/NiNH4PO4·H2O composites were analyzed using the limiting oxygen index (LOI), cone calorimetry (Cone), mechanical property tests, thermogravimetric analysis, and thermogravimetric–Fourier transform infrared spectroscopy. The results indicated that NiNH4PO4·H2O has proper thermal stability and greatly improves the flame retardancy of EP. The nanosheets outperformed the other morphologies; the EP/5% NiNH4PO4·H2O nanosheets have an LOI of 35.2%, which exceeds that of pure EP (24.7%). Furthermore, Cone showed that these nanosheets have the lowest peak heat release rate and peak smoke production rate, which are 69.1% and 36.5% lower than those of pure EP, respectively. NiNH4PO4·H2O can promote the formation of a stable char layer and release nonflammable gases, thus protecting the matrix by preventing heat and oxygen transfer and reducing the concentration of combustible gas. NiNH4PO4·H2O is expected to serve as a new high-efficiency flame retardant for EP.

Comparison of hydrogenated vegetable oil and biodiesel effects on combustion, unregulated and regulated gaseous pollutants and DPF regeneration procedure in a Euro6 car

The effects of traditional biodiesel (fatty acid methyl-esters, FAME) and a hydrotreated vegetable oil (HVO) were comprehensively investigated on a production Euro 6 diesel car, including fuel injection rate and timing, combustion analysis, emissions of regulated and unregulated pollutants, and regeneration of the diesel particle filter. The use of both biofuels is a part of the efforts to reduce emissions of greenhouse gases and health-relevant pollutants and to improve energy security and sustainability. HVO, albeit more expensive, offers benefits relative to FAME in terms of oxidation stability, injector fouling, energy content and cetane number. The car was fitted with an on-board instrumentation and subjected to a range of driving cycles on a chassis dynamometer. The fuel consumption calculated from instantaneous emissions data based on exhaust gas composition measured by an on-board FTIR and calculated exhaust flow matched directly measured fuel consumption within several percent on all fuels; differences in the consumption among the fuels correspond to different heating values. The combustion onset and maximum heat release rate were comparable for diesel and FAME but were advanced on HVO due to its higher cetane number, causing, at times, multiple distinct heat release peaks, suggesting that optimization of fuel injection timing for HVO might be beneficial. Emissions of methane and ammonia were negligible, of N2O were measurable and slightly lower for HVO than for other fuels, of formaldehyde were limited to cold engine accelerations and highest for FAME and negligible for HVO, of NO and NO2 were high on all fuels during all operating conditions except for the type approval test. The results confirm several relative advantages of HVO over RME, with penetration into engine lubricating oil during particle filter regeneration to be further investigated. The effects of HVO lubricity and other long-term effects were not evaluated here.

A novel strategy for simultaneously improving the fire safety, water resistance and compatibility of thermoplastic polyurethane composites through the construction of biomimetic hydrophobic structure of intumescent flame retardant synergistic system

The water resistance, compatibility and anti-dripping performance of flame retardant thermoplastic polyurethane (TPU) composites have still been a challenge in the fire science. Inspired by the hydrophobic surface structure of biomaterials, the hydrophobic charring agent N-methyl triazine-piperazine copolymer (MTPC) and modified magnesium oxide (MgO) were assembled on ammonium polyphosphate (APP) surface to prepare the hydrophobic intumescent flame retardant (HIFR) system. The constructed HIFR system presented excellent hydrophobic performance with the water contact angle of 139°. The HIFR was incorporated into TPU matrix. The tensile strength and elongation at break of TPU/10 wt% HIFR composites increased by 48 and 106% compared with that of TPU/10 wt% APP. Meanwhile, the specimens of TPU/10 wt% HIFR composites before and after water resistance tests achieved UL-94 V-0 rating without drippings and the limiting oxygen index value was 27.5 and 27.3%. TPU/HIFR composites still maintained excellent flame retardancy and mechanical properties after water treatment. Cone calorimeter tests revealed that the peak of heat release and smoke production, and CO yield of TPU/10 wt% HIFR composites were significantly decreased with the reduction of 87.0, 63.2 and 28.6% compared with that of neat TPU. The incorporation of HIFR effectively enhanced the fire safety for TPU composites. The investigation of flame retardant mechanism for TPU/HIFR demonstrated that HIFR catalyzed the TPU matrix charring in advance and the generated compact, homogeneous and partial graphitized char layer exerted barrier effect in condensed phase, and the released inert gases evoked dilution effect in gas phase. This presented work provided a novel promising approach for preparing TPU materials with excellent comprehensive performance as well as water resistance and highly flame retardant efficiency.

Flame retardancy of ceramic‐based rigid polyurethane foam composites

ABSTRACTIn this work, ceramic fillers zirconia and alumina powder were incorporated in the rigid polyurethane foams derived from modified castor oil and their impact on the mechanical, thermal, and fire performances of composite foams have been analyzed. It was observed that the addition of ceramic filler showed improved mechanical and thermal properties and best properties were shown by 6% zirconia with compressive strength of 6.61 MPa and flexural strength of 5.72 MPa. Zirconia also demonstrated an increase in T5% up to 260 °C. Cone calorimetry shows a decrease in peak of heat release from 118 to 84 kW m−2 and 94 kW m−2 by the incorporation of alumina and zirconia powder, respectively. Furthermore, total heat release (THR), smoke production rate (SPR), and total smoke release (TSR) were also found to decrease remarkably on the incorporation of ceramic fillers. So, these fillers have a great potential as an additive to incorporate good mechanical, thermal, and fire properties in bio‐based rigid PU foams. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48250.

Fresh and hardened properties of self-compacting concretes produced with diabase and gneiss quarry by-product powders as alternative fillers

This work investigated the use of diabase (D) and gneiss (G) quarry powders as alternatives to limestone filler (L) for self-compacting concrete (SCC) production. For this, SCCs with the different quarry powders, each one in three different particle size distributions, were produced. The shape and texture of the particles were evaluated through SEM image analysis. The fresh state properties of the SCCs were evaluated by the workability tests slump flow, V-Funnel, J-ring and VSI, and by rheometry. The cement hydration was evaluated in pastes by isothermal calorimetry up to 40 h, and thermogravimetric analysis (TGA) at 28 days. Finally, the compressive and splitting tensile strength, cement index and modulus of elasticity of the SCCs were determined at 28 days. The results showed that the SCCs containing D and G had fresh state properties equivalent to those containing L or only Portland cement, with slump flow of 700 ± 50 mm, V-Funnel time from 4.3 to 8.0 s, and VSI of 0 or 1. The isothermal calorimetry and TGA indicated a further hydration degree in the pastes containing D and G in comparison to L, reaching heat release peaks and hydrates contents (after 28 days) up to 25% and 35% higher, respectively. The SCCs containing D and G reached compressive strength, splitting tensile strength and modulus of elasticity respectively of 60.5 MPa, 6.1 MPa and 39.9 GPa. These values were up to 10%, 16% and 16% higher than those of the L-containing SCCs, respectively. Finally, the use of the quarry powders decreased the cement consumptions to achieve 1 MPa by up to 35% in comparison to the reference SCC (from 9.8 kg/m3.MPa for the reference to 6.3 kg/m3.MPa for D2-SCC). Overall, diabase and gneiss powders can be used as alternative fillers for the production of SCCs.

Performance enhancement and emission reduction by using pine oil blends in a diesel engine influenced by 1, 4-dioxane

The study to improve the characteristics in terms of performance, emission and combustion aspects without any modification to a direct injection compression ignition engine using pine oil blend and additive addition was executed. Biofuels known for their reduction in emission also degrades the engine’s performance value. To overcome this, pine oil mixture was used with an additive (1,4-dioxane). Pine oil taken at two different concentrations (P20, P40) and the additive at two varying proportions (5 ml, 10 ml) were utilized. In total, six pine oil mixtures were prepared and analyzed for the emission, performance and combustion aspects of the test engine and compared with diesel values. The result evidenced the rise of 3.88% and 5.57% for brake thermal efficiency and fuel consumption, respectively, for P20-10 ml blend compared with diesel. Contemplating the emission aspects, considerable decrease in pollutants (22.41% CO, 29.19% HC and 22.80% smoke) excluding NOx and CO2 at peak load conditions was depicted. NOx and CO2 increase about 7.23% and 25.41%, respectively. Combustion parameters like heat release rate and peak pressure of pine oil mixture exhibited inferior values compared with diesel. Only P20 blend with 10 ml additive exhibited values very close (a drop of 2.8% HRR and 2.4% CP) to that of diesel value. To conclude, out of half-dozen blends when compared with diesel, P20 with 10 ml additive proves as the best blend, providing much capable outcomes.

Facile fabrication of a novel polyborosiloxane-decorated layered double hydroxide for remarkably reducing fire hazard of silicone rubber

How to improve the flame-retardant efficiency and dispersion of layered double hydroxide (LDH) in silicone rubber (SR) is one of the biggest challenges for the application of halogen-free flame retardant SR/LDH nanocomposite. In this work, a novel and highly efficient flame retardant, i.e., polyborosiloxane decorated layered double hydroxide (PBS-d-LDH), was synthesized and incorporated into SR to prepare SR/PBS-d-LDH nanocomposite. Benefitting from the sulfonate and boron hydroxyl groups of PBS, PBS-d-LDH was easily exfoliated and dispersed in SR. PBS-d-LDH endowed SR with outstanding mechanical properties, thermal stability, flame retardancy and smoke suppression performance. When the content of PBS-d-LDH was only 5.0 phr, SR/PBS-d-LDH had a good self-extinguishing capability, and its peak heat release rate and peak smoke production rate were reduced by 54.4% and 61.5%, respectively. Furthermore, the Ti (temperature at 5% weight loss) and the residue of SR/PBS-d-LDH at 700 °C were increased by 37.0 °C and 23.5 wt%, respectively. The mechanism analysis revealed that when being burned, the crosslinking reaction of PBS and layer barrier effect of LDH showed a good synergism in the ceramization of condensed phase, which contributed to the prominent flame retardancy and smoke suppression of the SR/PBS-d-LDH nanocomposite. This work provides a promising strategy to prepare highly efficient flame retardant polymer.