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The article presents the results of research on electrically conductive hard-to-burn composite materials based on polyethylene, graphite, and some flame retardants. It is shown that optimal electrical conducting properties and the flammability rating (V0) in accordance with UL 94 test are achieved by modifying the graphite-containing composite material based on low-pressure polyethylene with ammonium polyphosphate and (or) aluminum hydroxide. It is shown that the percolation threshold of a composite material based on high-pressure polyethylene and graphite is observed at significantly higher values of the mass fraction of graphite. It is concluded that the reduction of the percolation threshold of polyethylene when filled with graphite is facilitated by an increase in the degree of crystallinity of the binder, and the formation of structured continuous conducting clusters in the composite material is observed at lower values of the mass fraction of the filler. As a result, the thermal conductivity and heat resistance of the composite material are increased owing to more efficient delocalization of the supplied heat. A number of electrically conductive hard-to-burn materials were obtained and characterized. These data allow us to directly adjust the values of the specific volume electrical resistance, physical and mechanical properties, heat resistance, and, to a certain extent, flame resistance.

The aim of this study is to investigate the effect of fiber length and loading on physico-mechanical and flammability properties of Cyrtostachys renda (CR) fiber-reinforced phenolic composites. Waste based Cyrtostachys renda (CR) fiber reinforced phenolic resin derived from cashew nut shell liquid (CNSL), bio-composite has been studied. Composites with alkali treated CR fiber length in the ranges of 1.18–0.6, 0.6–0.3 and less than 0.3 mm in 20 wt% and 40 wt% based on weight of phenolic resin were prepared by hot compression. Flammability, water absorption, tensile/flexural/impact tests were carried out on the composites and also characterized by scanning electron microscope (SEM). Composite containing 40 wt% fiber of length less than 0.3 mm has the highest tensile and flexural strengths of 34.27 MPa and 65 MPa respectively. It has been found that water absorption and thickness swelling increases as weight % of fiber increases. For the Underwriters Laboratories (UL 94), all the neat phenolic and addition with CR fiber exhibited NC and H-B classifications for vertical and horizontal respectively, however Limiting Oxygen Index (LOI), of neat phenolic dropped from 29.33 to 26 and 25 for 20 wt% and 40 wt% respectively. Morphology of the tensile fractured laminates revealed that micro pores in fibers are filled with phenolic resin, hence increases the interfacial bonding between fiber and the matrix. The research findings provision that CR fiber reinforced phenolic composites is potential to be utilized as green and biodegradable composites for interior components of automotive and aviation industry.

Purpose The flammability of poly-acrylate (PA) resin is a major disadvantage in applications that require flame resistance. Many studies, including the authors’ previous study, have proved that covalent-incorporated phosphorous-containing (P-containing) monomer onto the PA resin can exhibit better flame resistance than that by an additive approach. However, other properties such as thermal stability, coating properties are still deteriorated. To further improve the flame-retardancy and other comprehensive properties of the P-containing PA resin, in this study, melamine formaldehyde(MF) resin was used not only as a curing agent to enhance the coating properties of the PA resin, but also as a nitrogen-containing (N-containing) resin to form a P-N synergistic effect and therefore further improve its flame retardancy. Design/methodology/approach Epoxy resin phosphorous acid-modified (EPPA-modified) PA (EPPA-PA) resin was first prepared and then using MF resin as curing agent. The flame retardancy of the cured resin was tested by the limiting oxygen index (LOI) and UL 94 methods. The thermal stability of the cured resin was studied by TGA. The coating technology such as adhesion property, pencil hardness and anti-solvent properties were characterized according to methods of International Standards ISO2409-1992, ISO 15184-1998 and ISO-15184-2012, respectively. The micro-char morphology of the char residue was observed by SEM. Findings The results showed that by using MF resin as curing agent has provided the PA resin with excellent coating properties and thermal stability, but also gave a P-N synergistic effect which has greatly enhanced the flame retardancy of the cured resin. The cured resin system containing only 1.7 Wt.% P content and 5.3 Wt.% N content can reach a LOI of 26.9 per cent and pass the V-0 rating in the UL-94 test. Research limitations/implications This resin system releases formaldehyde due to the MF resin. Practical implications It is expected that the large-scale production of this EPPA-PA resin cured by MF resin system will enable practical industrial applications. Originality/value This method for the synthesis of a P- and N-containing PA resin system is newfangled.

This research aims to determine the mechanical properties of sugar palm fiber (Arenga pinnata Wurmb. Merr) (SPF)/glass fiber (GF)-reinforced poly(lactic acid) (PLA) hybrid composites for potential use in motorcycle components. The mechanical (hardness, compressive, impact, and creep) and flammability properties of SPF/GF/PLA hybrid composites were investigated and compared to commercially available motorcycle Acrylonitrile Butadiene Styrene (ABS) plastic components. The composites were initially prepared using a Brabender Plastograph, followed by a compression molding method. This study also illustrated the tensile and flexural stress–strain curves. The results revealed that alkaline-treated SPF/GF/PLA had the highest hardness and impact strength values of 88.6 HRS and 3.10 kJ/m2, respectively. According to the results, both alkaline and benzoyl chloride treatments may improve the mechanical properties of SPF/GF/PLA hybrid composites, and a short-term creep test revealed that the alkaline treated SPF/GF/PLA composite displayed the least creep deformation. The findings of the horizontal UL 94 testing indicated that the alkaline-treated SPF/GF/PLA hybrid composites had good flame resistance. However, alkaline-treated SPF/GF/PLA composites are more suitable materials for motorcycle components.

In this study, the flame-resistant epoxy syntactic foams with different content of hollow glass microspheres (HGM) were prepared by using aluminum diisobutylphosphinate (AlPBu) as flame retardant. Scanning electron microscope (SEM) images of the fracture surface of different epoxy syntactic foams showed that AlPBu particles had good compatibility with the matrix due to their similar polarities. And the limiting oxygen index, UL 94 test, cone calorimeter and thermogravimetric analysis were applied to characterize the flame retardation and thermal behavior of the foams. These results showed that AlPBu improved the flame retardancy of epoxy syntactic foams, while the HGM exhibit a complicated influence on the flame retardation, although both AlPBu and HGM enhanced the char residues and decreased the peak heat release rate as well as the total heat release of composites. In addition, swollen char layers mainly containing the HGM were generated after adding AlPBu. Then, the char residues of the foams after combustion were observed by SEM, and the results were applied to reveal the different fire behaviors of foams with different densities.

The biggest obstacle in using the wood as a building material is its lack of resistance against fire. In this study, it is aimed to provide resistance against this big obstacle in using the wood. In this sense, the novel flame-retardant wood composites were produced by using inorganic Turkish huntite and hydromagnesite minerals. For the production of composite material, the mineral was crushed, ground and screened to different sized fractions. Sawdust was used as a composite matrix. First, the mineral additive ratio in the composite was changed by keeping the size value of the additive material constant. Then, the contribution rate was kept constant, but the size values were changed. Hereby, the dependence on quantity and size was investigated. Mineralogical structure was determined by XRF, XRD and SEM-EDS devices. Thermal behavior was observed by the DTA-TG apparatus. Mechanical properties were evaluated by the bending test. UL-94 test apparatus was used to determine the flame-retardant properties of the wood composites. It was concluded that the wood composites, containing inorganic minerals, gain resistance against fire. Besides, the flame-retardant properties of the wood composites were improved as the mineral content increased and the size was reduced.

Mica-type clays nano-dispersed In commodity polymers. These “nanocomposites” exhibit the unusual combination of reduced flammability, in the form of lower peak heat release rates, and However, the details of the fire retardant mechanism are not well understood. In October of 1998 a NIST-industrial consortium was formed to study the flammability of these unique materials. The focus of research within this consortium was to development a fundamental understanding of the fire retardant (FR) mechanism of polymer clay nanocomposites. We report here on some of the results of the first year of this study; we focus our discussions on the results for polystyrene (PS) a polymer system commonly used in flame retarded applications such as information technology (IT) equipment. The most important aspect of the nanocomposite approach is the combined improvement in both clay dispersion. We also report on our recent efforts to address these issues; specifically, our efforts to develop thermally stable immidazolium treated clays, and using solid state NMR to evaluate clay dispersion and alkyl ammonium stability.

The fire behavior of polymers is examined primarily with the time-dependent heat release rate (HRR) measured with a cone calorimeter. The HRR is used to examine the fire behavior of materials with and without flame retardants, especially Polypropylene (PP-Copo) and Polyethylene (PE-LD). Polypropylene is stored for up to 99 days under normal conditions and the heat release rate shows especially changes about 100 s after irradiation with cone calorimeter, which may be caused by aging effects. The effect of crosslinking to the burning behavior of PP was examined too. Polyamides (PA 6) are irradiated with a radiation intensity of 25 kW/m2 to 95 kW/m2 and fire-related principles between radiation intensity and time to ignition can be derived from the measurement results. In order to comprehensively investigate the fire behavior of PP (also with flame retardant additives), the samples were also exposed to a flame, according to UL 94 with small power (50 W) and is inflamed with the power of a few 100 W. The irradiation causes different trigger mechanisms for the flame retardant additives in a plastic than the flame exposure. It is shown that the compound, which is favorable for irradiation, is not necessarily good for flame exposure. It can be seen that expandable graphite alone or with the addition of other additives is a very effective flame retardant for PP.

In the current study, huntite hydromagnesite (HH) was used as flame retardant additive in poly (lactic acid) (PLA) to produce green flame retardant composites. The effects of HH amount, particle size and surface modifications on the flame retardant, thermal and mechanical properties were investigated. The properties of the composites were investigated using limiting oxygen index (LOI), horizontal and vertical burning test (UL 94), mass loss calorimeter, thermogravimetric analysis, tensile test, impact test and dynamic mechanical analysis. According to results, the flame retardant PLA composites with different UL-94 ratings (HB, V2, V0) were produced. The LOI value increased as the added amount of HH increased. The highest LOI value of 34.2 was achieved with the addition of 60 wt% HH. Surface modifications had no remarkable effect on the flammability properties of the composites. The addition of HH reduced the tensile and impact strengths and improved the elastic modulus of the composites as the added amount of HH increased. The addition of HH with large particle size deteriorated the flammability properties and tensile strength despite of the increase in impact strength. Surface modifications improved the mechanical properties of the composites due to the improvement in interfacial adhesion between HH and PLA.

Derivatives of 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro-[5,5]undecane-3,9-dioxide (SPDPC) are of increasing interest as flame retardants for polymeric materials. In addition, SPDPC is also an important intermediate for the preparation of intumescent flame retardants (IFRs). However, low efficiency and undesirable dispersion are two major problems that seriously restrain the application of IFRs as appropriate flame retardants for polymer materials. Usually, the functionalization or modification of SPDPC is crucial to acquiring high-performance polymer composites. Here, a small molecule spirocyclic flame retardant diphenylimidazole spirocyclic pentaerythritol bisphosphonate (PIPC) was successfully prepared through the substitution reaction between previously synthesized intermediate SPDPC and 2-phenylimidazole (PIM). Phenyl group and imidazole group were uniformly anchored on the molecular structure of SPDPC. This kind of more uniform distribution of flame retardant groups within the epoxy matrix resulted in a synergistic flame retardant effect and enhanced the strength of char layers to the epoxy composites, when compared to the unmodified epoxy. The sample reached a limiting oxygen index (LOI) of 29.7% and passed with a V-0 rating in the UL 94 test with the incorporation of only 5 wt % of as-prepared flame retardant PIPC. Moreover, its peak of heat release rate (pHRR) and total heat release (THR) decreased by 41.15% and 21.64% in a cone calorimeter test, respectively. Furthermore, the addition of PIPC has only slightly impacted the mechanical properties of epoxy composites with a low loading.

Fires have been a danger to human beings for the centuries. As people lost their lives and property in fires, they tried to fight the fire and their efforts in this area continued increasingly. Unfortunately, it is still not possible to completely reset the risk of starting the fire. But it seems likely to extinguish immediately after the fire has started, and this is very important to save people’s lives. Scientists have been working in this field in recent years; they are concentrated on producing fire-resistant materials using different materials. This can be provided by different ways; either fire-resistant material can be produced new, or the fire resistivity can be provided by incorporating the additive material into a flammable material. In our previous studies, we used huntite and hydromagnesite minerals to give fire resistance property to polymer materials, very successful results were obtained. In this study, huntite and hydromagnesite minerals were used for accompanying with zinc borate in polypropylene composites in order to increase the flame retardant property of a polymeric materials. Different content of minerals were blended with polypropylene, and composites were produced by twin-screw extruder for observing synergistic effect. Scanning electron microscopy (SEM) analyses were conducted to determine the structural and morphological properties of the composites. Thermal properties were determined according to thermogravimetric analysis (TGA). Tensile and three point bending tests were carried out to obtain mechanical properties. Flame retardant performance was evaluated according to UL 94 vertically flammability test. It was concluded that very good synergistic effects were obtained that zinc borate was significantly influential with huntite/hydromagnesite in the flammability characteristics of composites because higher char formation is observed with zinc borate addtion. Moreover, the zinc borate reduced the smoke generated during combustion.

We present the development of a high-performance flame-retardant vinyl ester (FR-VE)/flax fabric (FF) biocomposite through a hybrid approach using vacuum-assisted resin transfer molding. FF was modified to form FR fibers (mFF) using surface treatment with varying amounts (5–20%) of ammonium polyphosphate (APP), and the FR-VE/mFF composites were fabricated by including flame retardants such as chitosan (CS), APP, and modified CS (NCSAPP). The optimized mFF (15% APP) exhibited enhanced thermal stability (38 wt% residue at 700 °C) and it achieved a V0 rank in the UL 94 test. In addition, the dual effects, i.e., the effects modification of the reinforcement and inclusion of the FRs into the matrix, improved the properties of the FR-VE/mFF composites, providing them with high thermal resistance (28 wt% residue at 700 °C), and fire resistance (V0 rank in the UL 94 test), and self-extinguishing characteristics with a suppressed peak heat release rate (69%), total heat release, and smoke production rate.

The rapid mass calorimeter (RMC) was used as a screening tool based on accelerated fire testing to assess flame-retarded thermoplastic polyurethane (TPU). The reliability of RMC results was proven with the cone calorimeter as reference fire test. The influence of melamine cyanurate (MC) concentration on the fire performance of TPU was investigated, along with some flame-retardant combinations such as MC with aluminium diethylphosphinate (AlPi), aluminium trihydrate (ATH), and melamine polyphosphate (MPP). The two-stage burning behaviour of TPU was investigated in detail; the first stage corresponds mainly to the hard segments' decomposition and has a much lower effective heat of combustion (EHC) than the second stage, in which mainly the soft segments decompose and an intensive liquid pool fire is observed in the cone calorimeter set-up. In addition to fire testing with the cone calorimeter, RMC, and UL 94 flammability tests, the decomposition of the materials was investigated using thermogravimetric analysis coupled with infrared spectrometry (TGeFTIR). TPU/MC/AlPi shows the most promising results, achieving V-0 classification in UL 94 and reducing the extreme peak heat release rate (PHRR) of the liquid pool fire from 3154 kW/m2 to 635 kW/m2. Using MC/AlPi/MPP enhances the latter PHRR reduction further. The decomposition products identified in the gas phase via TGeFTIR reveal specific MCeAlPi eMPP interactions, as they differ from products seen in systems with MC/AlPi or MC/MPP. Correlations between RMC and cone calorimeter results were examined and presented in the final part of the paper. Several characteristics correlate strongly, pointing out that RMC is a reliable high-throughput fire testing method to screen multicomponent flame-retardant solutions in TPU.

Incorporation of 10 wt% 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) in polybutylene succinate (PBS) showed a significant improvement of fire behavior at the UL-94 test (3.2 mm): (i) V-0 rating and no ignition of the bar for PBS/DOPO with dripping but with no ignition of the cotton whereas (ii) no classification for neat PBS with dripping and with ignition of the cotton. To fully understand these two different phenomena, an optimized UL-94 instrumentation was developed. Thermocouples embedded in the bar measures heat gradient and infrared (IR) camera equipped with a specific filter permits estimating heat gradient in the bar and surface temperature of the falling drop respectively. The main advantage of this optimized UL-94 instrumentation is to get measurement in situ and in dynamic. This instrumentation has successfully captured the temperature evolution of a falling drop during a UL-94 test. It was shown that the drops of neat PBS exhibits a constant temperature of 453 ± 10 °C when detaching the bar. However the drops' temperature of PBS/DOPO varied during the UL-94 test when they detach the bar: the drops formed at around 403 ± 10 °C at the end of the first ignition, whereas at the end of second ignition they detach the bar at about 313 ± 15 °C. Neat PBS exhibited temperature at least 50 °C higher than PBS/DOPO when the drops touched the cotton: 435 ± 5 °C for neat PBS at the end of first ignition vs. 385 ± 10 °C for the PBS/DOPO at the end of first ignition vs. 295 ± 15 °C for the PBS/DOPO at the end of second ignition. This can explain why the drops of PBS can ignite the cotton whereas those of PBS/DOPO cannot. Additionally, IR camera images indicate the change of rheology by incorporation of DOPO into PBS. A measurement of viscosity by the rheometer showed that PBS/DOPO has lower viscosity than neat PBS.

The aim of this work was to study the influence of a high efficient halogen-free phenylphosphonic amide flame retardant (FP1) to epoxy resin (brand name RTM6) on the rheological, mechanical and water absorption properties of the carbon fiber/RTM6 epoxy composite (CFR). With a 8 wt% loading FP1 in RMT6, the processing of CFR/FP1 was able to use the equal condition with that of CFR since the viscosity of RTM6 was maintained at a similar level in the minimum viscosity temperature region. The addition of FP1 showed negligible impacts on the interlayer share strength (ILSS) and in-plane share strength (IPSS) of CFR. The interfacial strength between RTM6 matrix and carbon fiber was decreased due to the impact of FP1 on cross-linking density and polarity of RTM6. The flame retardant efficiency of FP1 showed difference in presence of carbon fiber or not in RTM6. RTM6/FP1 (8 wt%) had a LOI value of 38%, achieved a V-0 rating at thickness of 3.2 mm in UL 94 test and showed 60% reduction in peak of heat release rate. RTM6/carbon fiber/FP1 (8 wt%) had a LOI of 43%, while it showed reduced performance in UL 94 and cone calorimeter tests.

In this study, a novel halogen-free flame retarded form-stable phase change material (PCM) was designed and prepared, selecting paraffin as the thermal-energy storage material and epoxy resin (EP) as the supporting material; furthermore, a novel flame retardant curing agent PEPA–TMA (2,6,7-trioxa-1-phosphabicyclo-[2.2.2]-octane-4-methanol reacted with trimellitic anhydride) and melamine cyanurate were combined into the energy-storing material to obtain the flame retarded PCM. Thermal performances of the PCM were investigated through differential scanning calorimeter, the data suggested that the PCM had relatively high latent heat, and values normalized to the amount of paraffin were lower than the theoretical values. The thermogravimetric analysis displayed that the intumescent flame retardant (IFR) could improve the charring of the PCM, and the PCM had passed a UL 94 V-0 test when the IFR loading reached 24 wt%. The cone calorimeter results further proved that the PCM had better flame retardancy. The morphology of the composites was observed by scanning electron microscopy, and the images showed that the paraffin could be dispersed uniformly in the materials, which formed a three-dimensional network by EP.

In this study, a facile solvothermal approach for preparing anhydrous manganese hypophosphite (A-MnHP) microtubes was demonstrated for the first time by using manganese chloride and hypophosphorous acid in mixed solvents, followed by fabricating A-MnHP-based poly(lactic acid) (PLA) composites via a melt-blending method. Owing to the unique morphology of A-MnHP, the tensile strengths of the PLA composites with 1 wt%, 5 wt% and 10 wt% A-MnHP are approximately 17%, 7% and 3% higher than those of neat PLA, respectively. Compared to neat PLA, PLA composite containing 15 wt% A-MnHP (PLA/A-MnHP15) exhibited lower peak heat release rate (50% reduction), total heat release (13% reduction), peak CO2 and CO productions (50% and 53% reductions), which also passed UL 94 V-2 rating test with high limiting oxygen index (27.5%). The combustion temperature change during the cone calorimeter tests showed that PLA/A-MnHP15 showed the lowest combustion temperature, achieving the best fire safety performance. Residue analysis indicated that the presence of A-MnHP resulted in the formation of continuous and compact char residues composed of aromatic structure and phosphorous-rich inorganic structure, retarding the permeation of heat, oxygen transfer and escape of volatile degradation products.

10-hydroxy-9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-OH) has been successfully covalently grafted onto the surfaces of multi-walled carbon nanotubes (MWCNTs) to obtain DOPO-functionalized MWCNTs (MWCNT-DOPO-OH) by a three-step process. The resultant core-shell nanostructured MWCNT-DOPO-OH was introduced into aluminum hypophosphite/poly(lactic acid) (AHP/PLA) flame retardant systems via melt blending to improve both flame retardancy and mechanical properties. AHP/PLA/MWCNT-DOPO-OH nanocomposites with synergistic effect of 1 wt.% MWCNT-DOPO-OH and 14 wt.% AHP were shown to be effective in improving flame retardancy with UL 94 V-0 rating and limiting oxygen index (LOI) value of 28.6. And these flame-retardant nanocomposites show a usable Tg higher than 57.8 °C and much higher char yield for preventing the anti-dropping. Moreover, a cold rolling process was performed for AHP/PLA/MWCNT-DOPO-OH nanocomposites to further improve the mechanical properties for secondary processing. For 1 wt.% MWCNT-DOPO-OH loading PLA nanocomposites, the tensile strength increased from 69.5 MPa to 77.9 MPa and 82.0 MPa, and the fracture strain increased from 17.9% to 27.5% and 120%, at rolling ratios of 30% and 50%, respectively, indicating that MWCNT-DOPO-OH modified PLA was homogenized plastic deformation during the rolling process.

In the current study, huntite and hydromagnesite (HH) was used as flame-retardant additive in linear low-density polyethylene (LLDPE). The effect of HH amount on the flame-retardant and mechanical properties of the composites was investigated. The compatibilizer (ethylene butyl acrylate) use and the surface modifications with stearic acid and silane coupling agent were used in order to improve the mechanical properties of the composites. The mechanical properties of the composites were studied using tensile test and dynamic mechanical analysis. The fire-retardant properties of the composites were investigated using limiting oxygen index (LOI), mass loss calorimeter, vertical (UL 94 V) and horizontal (UL 94 HB) burning tests. According to the flammability test results, LOI value increased, horizontal burning rate reduced as the added amount of HH increased, whereas UL 94 V rating remained burn to clamp. According to the mechanical test results, the addition of HH reduced the tensile strength and elongation at break values and increased the elastic modulus and the β transition temperature of the LLDPE as the added amount increased. Only the compatibilizer use improved the flammability properties of the composites with improved tensile strength. Both stearic acid and silane modification merely increased the toughness of the composites.

Influence of wool fibres (WF) in improving the flame retardant and mechanical properties of polypropylene/kenaf fibre/intumescent ammonium polyphosphate (PP/KF/APP) composites is described. Flammability of PP/KF/APP/WF composite was evaluated using cone calorimetry, UL 94-V vertical burning tests and thermo-gravimetric analysis, and compared to results of similar composites which contained an ultraviolet ray stabiliser and colourant combination (PP/KF/APP/UVC). Tensile, bending and impact test analyses were also conducted on both sets of composites. PP/KF/APP/WF system had stable residual char at elevated temperatures, significantly improving fire protection. High degree of cross-linked stable char formation and residual char in PP/KF/APP/WF composite provided sufficient evidence of synergistic effect of wool. WF increased the tensile modulus of the composite by approximately 16%, while UVC (together with APP) improved the composite's flexural stiffness by 21%.

Basic paths towards fully green flame retarded kenaf fiber reinforced polylactic acid (K-PLA) biocomposites are compared. Multicomponent flame retardant systems are investigated using an amount of 20 wt% such as Mg(OH)2 (MH), ammonium polyphosphate (APP) and expandable graphite (EG), and combinations with silicon dioxide or layered silicate (LS) nanofillers. Adding kenaf fibers and flame retardants increases the E modulus up to a factor 2, although no compatibilizer was used at all. Thus, in particular adding EG and MH decreases the strength at maximum elongation, and kenaf fibers, MH, and EG are crucial for reducing the elongation to break. The oxygen index is improved by up to 33 vol% compared to 17 vol% for K-PLA. The HB classification of K-PLA in the UL 94 test is outperformed. All flame retarded biocomposites show somewhat lower thermal stability and increased amounts of residue. MH decreases the fire load significantly, and the greatest reduction in peak heat release rate is obtained for K-PLA/15MH/5LS. Synergistic effects are observed between EG and APP (ratio 2:1) in flammability and fire properties. Synergistic multicomponent systems containing EG and APP, or MH with adjuvants offer a promising route to green flame retarded natural fiber reinforced PLA biocomposites.

A siloxane compound (MVC) and a bi-group phosphaphenanthrene/triazine compound (TGD) were employed in epoxy thermosets to explore high-efficiency flame retardant system. With only 1 wt.% MVC and 3 wt.% TGD, epoxy thermoset passed UL 94 V-0 rating test and achieved an limited oxygen index (LOI) value of 34.0%, which exhibited an excellent flame retardant effect. The MVC/TGD system not only decreased peak value of heat release rate and effective heat of combustion but also imposed the improved charring ability to thermosets, thereby outstandingly reducing the flammability of 1%MVC/3%TGD/EP. Compared with the fire performance of 4%TGD/EP and 4%MVC/EP, MVC/TGD system possessed obvious flame retardant synergistic effect, mainly depending on the general improvement of flame inhibition, charring, and barrier effects on thermoset during combustion. The evolved gas analysis combined with the condensed-phase pyrolysis product analysis jointly revealed the details of the changed pyrolysis mode.

Thermoplastic polycarbonate (PC) and nylon 6 (NY) composites with cenosphere and hollow glass beads were prepared and their mechanical, rheological, thermal and flame retardency properties were studied. The flexural behavior of the composites increased after loading with cenosphere and hollow glass beads. The tensile strength of the PC composites was enhanced up to 80 N mm–2 as compared to pure PC while no remarkable change was observed in case of nylon 6 composites. Study of thermogravimetric Analysis (TGA) showed that the thermal stability of all the composites (Polycarbonate/cenosphere, Polycarbonate/hollow glass beads, Nylon 6/cenosphere and Nylon 6/hollow glass beads) increased. It was concluded that both the fillers enhanced the non-flammability of the polymers. Limiting oxygen index (LOI) value of all the composites showed an increase with increase in the concentration of filler. The optimal results of LOI and UL 94 were observed in composites with 8% cenosphere and 12 % cenosphere in case of Nylon 6. Cenosphere led to superior mechanical properties of polycarbonate and nylon 6 in comparison to hollow glass beads which suggested the composites can find use in automotive, industrial, pump component and for manufacturing of light weight parts in aeronautic industry at lower economic value.

In this work, a phosphorous-based compound (DOPO-ICN) was obtained by a two-step process. 9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide (DOPO) reacted with formaldehyde firstly, followed with reacting with 1,6-hexane diisocyanate (HDI). The chemical structure of DOPO-ICN was confirmed by Fourier transform infrared spectroscopy (FTIR) and 1H NMR. The influence of DOPO-ICN on the mechanical and flammability properties of jute/PLA composites was studied. Compared to DOPO, DOPO-ICN improved the tensile, flexural and impact strength of the flame retardant jute/PLA composites. Moreover, the flammability of jute/PLA composites with different DOPO and DOPO-MA loading was investigated by thermogravimetric analysis (TGA), UL 94 test and limiting oxygen index (LOI) measurements. The results showed that DOPO-ICN imparted the flame retardancy to the jute/PLA composites.

Summary The effect of zinc borate (ZnB) was studied on the flame retardant and thermal properties of thermoplastic polyurethane containing huntite-hydromagnesite. The flame retardant properties of thermoplastic polyurethane–based composites were investigated using limiting oxygen index, vertical burning test (UL 94), thermogravimetric analysis, and mass loss calorimeter. No remarkable effect of ZnB was observed on the flammability properties of composites. UL 94 rating did not change regardless of the added amount of ZnB, and the slight increase in limiting oxygen index value was observed at ratio of 1:1. The adjuvant effect of ZnB was observed during the mass loss calorimeter studies by increasing the barrier effect of the residue in the condensed phase and by increasing the formation of incombustible gasses in the gas phase. The highest fire performance was achieved at ratio of 1:1.

Epoxy/nanoclay composites containing ammonium polyphosphate (AP) were prepared by in situ polymerization method using compression molding machine. XRD patterns indicated the formation of epoxy/clay nanocomposites. The glass transition temperature measured by DSC was increased with the addition of nanoclay as well as AP separately in epoxy matrix but decreased when nanoclay and AP added together. On adding AP, the epoxy composites showed early start of degradation but after 400 °C composites became stable and gave high char yield in thermogravimetic analysis. Epoxy composites containing 10% AP accomplished the flame retardant property with V-0 rating in UL-94 test.

In this work, fire inhibition performance of four flame retardant formulations of brominated flame retardant (BFR: GreenArmor ® ), antimony(III) oxide (Sb 2 O 3 ) and high impact polystyrene (HIPS) is reported. The standard Underwriters Laboratory (UL 94) vertical burn test was applied for assessing the flame retardancy of a variety of polymer blends. A formulation having 13.3 wt% GreenArmor ® , 4 wt% Sb 2 O 3 and 82.7 wt% HIPS, named sample D, successfully passed the flame test and was rated V-0. The other formulations with deficient composition exhibited low flame retardancy, as expected. The X-ray grating interferometry method is introduced for probing the 3D internal structures across the burnt UL 94 flame retarded polymer blend formulations to present the detailed mechanisms of flame retardancy. The X-ray images revealed several features for the formulation (sample D) that passed the UL 94 test: heat-induced dissolution of BFR and Sb 2 O 3 residual particles, formation of gas bubbles inside the burnt polymer test bar, deflation of gas bubbles in a char layer through a microcrack, and thick char layer development, defined by the Br and Sb concentration profile to a depth of 100–220 μm. Also, the X-ray images show clear differences between formulations that pass and fail the UL 94 test. X-ray grating interferometry imaging is proposed as a novel technique for assessment of new generation flame retardants.

The effects of cobalt acetate (CoAc), manganese acetate (MnAc), nickel acetate (NiAc) and zinc acetate (ZnAc) as fire retardant additive in intumescent polypropylene (PP) formulations containing PP/ammonium polyphosphate (APP)/pentaerythritol (PER) are reported. The limiting oxygen index (LOI) and vertical burning (UL94) tests and cone calorimetry were used to quantify the enhancement. Environmental chamber rheometry, thermal gravimetric analysis and the morphology of the residual char were used to investigate the mechanism of enhancement. The incorporation of small quantities of metal acetates had a significant influence on the fire behaviour. As an example, 0.7 wt% MnAc improved the UL 94 rating of PP/APP + PER (mass ratio 100/25, with APP/PER = 3/1) sample from V-2 to V-0, while 1 wt% MnAc reduced the peak heat release rate and the total heat release by 18% and 12% in the cone calorimeter. Rheological data, cone calorimetry, and photographs of the residual char showed how the fire retardancy of the systems were affected by the melt viscosity, which depended on the loading of metal acetate. During thermal decomposition, the metal acetates promote the crosslinking of the polymer and the fire retardant, reinforcing the protective intumescent layer. While, the effect is most potent at the optimal metal loadings. At higher MnAc loadings, the benefit of a stronger char is overwhelmed by the adverse effect of crosslinking on the transition char layer. Thus, this paper offers a new insight into the mechanism of the intumescent fire retarded PP system.

The limitation of fire class and halogen-containing flame retardants are two significant issues for polystyrene-based insulation materials. In this chapter, the necessity of external thermal insulation composite systems and related concepts are briefly introduced. Then, based on the approaches in the literature to halogen-free flame retardants for polystyrene, melamine-derived and expandable graphite-based substances on polystyrene production and properties are investigated. Flame retardants were added both during and after the polymerization reaction. Chemical and mechanical properties are investigated by means of elemental analysis, high-temperature gel permeation chromatography, thermal gravimetric analysis, tensile and flexural strength together with Young’s and elastic moduli. Moreover, the horizontal fire class tests were also performed. According to results, except virgin PS all blended materials passed UL 94 HB test.

The article describes the investigation of the mechanical and thermal properties of polymer composites with flax or hemp fibers and polyethylene matrix (LDPE and LLDPE) with and without the maleic anhydrite as a compatybilizer. Also for increase the flammability resistance the 3 types of special flame retardants (5% by weight) were used as modifiers in the study. The composites with 3 and 5% by weight of flax and hemp fibers in the LDPE matrix have been prepared using a twin screw extruder, pulverizer and rotational molding machine. The influence of the flax and hemp content on mechanical and thermal properties (tensile test, DSC, Vicat softening temperature and UL 94 test) of obtained polymer composites has been presented. Also the structure of the prepared composites has been studied using the scanning electron microscopy - SEM. On the basis of the obtained results, it was found that modification of LDPE with flax or hemp fibers in the analyzed concentration range causes small improvement or does not significantly affect the tested properties of LDPE polymer. The use of flame retardants in the amount of 5% for most composites has a positive effect on flame retardancy. The study shows also that big differences in tested properties compared to unfilled LLDPE are visible for composites based on the LLDPE matrix with maleic anhydride. The presented preparation method and properties of obtained materials confirms the possibility of using this type of composites in production of rotational molded parts.

Most of polymeric materials, when exposed to high temperatures, heat flows or an open flame, are capable of exothermic oxidation reactions – combustion. That is why polymeric materials are fire hazardous. The studies on creating a non-flammable polymer materials are crucial, as such products can make our everyday life a lot more safe. Studies have been carried out to assess the effectiveness of the action of two types of fire retardants (graphene and an organic phosphorus-containing compound DOPO-THPO), introduced into an epoxy resin. Evaluation of the effectiveness of the fire-retardant action was carried out by the methods of oxygen index (OI) and flammability according to UL 94. For the investigated compositions, it was found that there is no direct correlation between the value of the oxygen index and the ability of the samples to maintain self-combustion. For these compositions, the total duration of residual combustion in vertical tests and the speed of flame propagation in horizontal tests are naturally correlated. It was found that if the total duration of combustion of five samples during vertical tests is 500 seconds or less, then these compositions during horizontal tests will fade, that is, formally, their flame propagation speed will be equal to zero.

Expanded polystyrene (EPS) foams were flame retarded using ammonium polyphosphate (APP) and nano-zirconia (nano-ZrO2) by means of phenolic resin as a binder. It is found that the incorporation of a small amount (5 phr) of nano-ZrO2 into the APP flame-retarded EPS foams leads to 19% increase in flexural strength and 38% increase in compressive strength. Flame-retardant properties of the flame-retarded EPS foams were investigated by limiting oxygen index (LOI), UL-94 and cone calorimetry test (CCT). The LOI of the APP flame-retarded EPS foams in presence of nano-ZrO2 is above 31%, and the UL 94 V-0 rating can be reached. The CCT test results indicate that the APP flame-retarded EPS foams containing nano-ZrO2 have lower peak heat release rate, average effective heat of combustion and average specific extinction area. Moreover, thermal decomposition of the flame-retarded EPS foams was investigated by thermogravimetric analysis (TGA) and the TGA results illustrated clearly that the addition of nano-ZrO2 into the APP flame-retarded EPS foams leads to an increase in the residual char yield. The reason for the increase is possibly because ZrO2 may react during combustion process with pyrophosphoric acid produced from the thermal decomposition of APP to form zirconium pyrophosphate (ZrP2O7) confirmed by XRD studies of the char, which is helpful to improve the formation of the char. The XPS results showed that the ratio of oxidized carbons in the char increases with the presence of nano-ZrO2.

Aluminum monomethylphosphinate (MeP-Al) was synthesized and applied as a flame retardant for epoxy resin (EP). The structure of MeP-Al was characterized with FTIR, 1H NMR, 31P NMR and XRF. Curing reaction monitoring, thermal analysis, evolved gas and solid residue analysis, flammability tests (LOI, UL 94), microcombustion calorimeter and chemical analysis of residues were used. 20 mass% of MeP-Al provides EP with desired flame retardancy and anti-dripping property. The formulation passes the UL 94 V0 rating with LOI value of 29.6 %. MeP-Al mainly acts in the solid phase, and minority acts in the gas phase. P–H bond in MeP-Al can react with the unsaturated bond of compounds coming from decomposition of EP to form the condensed and stable phosphate salts in the solid phase. The firm char is a good barrier to avoid heat transfer and progressive degrading of the inner material.

Mg-Al-Fe ternary-layered double hydroxides (LDHs) were synthesized by a calcination-rehydration method using Bayer red mud. The products were characterized using X-ray diffraction and thermogravimetric analysis. The flammability and thermal degradation of ethylene-vinyl acetate/layered double hydroxides/zinc borate (EVA/LDHs/ZB) composites were studied with limiting oxygen index, UL 94, cone calorimeter test, smoke density test, and thermogravimetry-Fourier transform infrared spectrometry. Although limiting oxygen index value of the composites decreased with increasing ZB amount, a suitable addition of ZB can apparently improve the UL 94 rating of the material. The heat release rate of the 5% ZB containing ternary composites decreased compared with the EVA/LDHs composites. It is obtained from smoke density test that ZB could help smoke suppression. The ternary composites possessed a higher thermal stability than the EVA/LDHs composites. Copyright © 2016 John Wiley & Sons, Ltd.

The flame retardancy of 2, 2-bis(4-glycidyloxyphenyl)propane (DGEBA)-aluminum diethylphosphinate (AlPi) nanocomposites (EP-AlPi/(P − x), x = 1, 2, 3 %) was greatly enhanced by ultrasonic dispersion of nano-sized AlPi into epoxy resin. The UL 94 V-0 rating can be reached for EP-AlPi nanocomposites with a relatively low addition amount of AlPi (on the account of 8.4 wt% or phosphorus content of 2 wt%) as well as the LOI value over 37.2. The glass transition temperature (T g) enhanced properties were investigated by DTA, which showed that: T gs were about 5 °C higher than that of neat epoxy resin; T g increased along with content increasing of AlPi. Based on TGA results under a non-isothermal condition, the thermal degradation kinetics of EP-AlPi/(P − x) composites were studied by Kissinger’s, Ozawa’s, Flynn–Wall–Ozawa’s and Coast-Redfern’s methods, which suggested the conversion function f (α) = 1/2α −1 or f (α) = [−ln(1 − α)]−1 for EP-AlPi/(P − 1 %); f (α) = [−ln(1 − α)]−1 for EP-AlPi/(P − 2 %) and EP-AlPi/(P − 3 %) during the investigated process. The epoxy resin nanocomposites obtained in this study are green functional polymers and will become flame retardant potential candidates in electronic fields such as printed wiring boards with high performance.

Two kinds of nano-metallic oxides (nano-Al2O3 and nano-ZrO2) were introduced separately into phenolic (PF) foams, and a series of PF foams modified with different loadings of the two nano-oxides were prepared. The test results of mechanical properties indicated that the flexural, compressive and impact strengths of the PF foams, modified by nano-Al2O3 at 5 phr loading, increased by 33, 46 and 51 % in the above order, and the strengths of the PF foams modified by nano-ZrO2 at 5 phr loading increased by 31, 30 and 49 % in the same order, compared to the corresponding data of pure PF foam. The pulverization ratio of the modified PF foams decreased gradually with the increase in nano-oxides contents. The pulverization ratio of the PF foam modified by nano-oxides at 5 phr, decreased to 2.3 % for Al2O3 and that of ZrO2 decreased to 2.2 %, which were quite lower than the pure PF foam value of 8 %. The combustion characteristics of the PF foams, modified by the nano-oxides, were evaluated by the limiting oxygen index (LOI), UL-94 and cone calorimetry tests. The LOI values of the foams modified by both nano-Al2O3 and nano-ZrO2 decreased slightly with an increase in the loading of the nano-oxides, still all above 36 %. The UL 94 test results indicated that all foams could pass a V0 rating. The cone calorimeter results showed that the peak heat release rates of the modified foams were lower than 50 kW/m2. Moreover, thermal stability of the foams modified by the nano-oxides was investigated.

This article mainly studies synergistic flame retardant effects and smoke suppression properties of iron-graphene (IG) and aluminum hypophosphite (AHP) on thermoplastic polyurethane (TPU), AHP used as main flame retardants and IG used as synergistic agents. A high concentration of TPU/IG masterbatch was prepared by solution-blending method, and then TPU/AHP/IG composites were prepared by melt-blending method. Then, the flame retardant effects of all TPU composites were tested using limiting oxygen index (LOI), UL 94 test, cone calorimeter test (CCT), scanning electron microscopy (SEM), thermogravimetric analysis (TG) and thermogravimetric/fourier transform infrared spectroscopy (TG-IR). Remarkably, with 0.25 wt% content of IG and 9.75 wt% content of AHP, sample reached UL 94 V-0 rating, and the LOI value increased by 31.5 vol%, pHRR value decreased by 90% and pSPR value decreased by 72%, etc. SEM images show that char residues become more complete and present lamellar structure. TG-IR data reveal that the incorporation of AHP and IG promoted the release of H 2 O and CO 2 , meanwhile reduced harmful gases release.

A comparison of melamine salt of pentaerythritol phosphate (MPP), and a synergistic agents, iron–graphene (IG) was performed in thermoplastic polyurethane (TPU) by masterbatch-melt blending on thermal and flame retardant properties. The flame retardant properties of TPU composites were characterized by limiting oxygen index (LOI), UL 94 and cone calorimeter test (CCT). The CCT results revealed that IG can significantly enhance flame retardant properties of MPP in TPU. The peak heat release rate of neat TPU and flame retardant TPU/MPP composites decreased from 2192.6 and 226.7 to 187.2 kW/m2 compared with that of TPU containing 0.25 wt% IG. The thermal stability and thermal decomposition of TPU composites were characterized by thermogravimetric analysis (TGA) and thermogravimetric/Fourier infrared spectrum analysis (TG-IR). The results indicated IG and MPP can improve the thermal stability of TPU. The formation of thermal conductive network by IG can promote the decomposition of MPP into nonflammable melt, which can play the role of heat barrier and restrict the diffusion of fuels into combustion zone and access of oxygen to the unburned fuels. Copyright © 2016 John Wiley & Sons, Ltd.

The relationship between the morphology, flammability and mechanical properties of layered silicate-polyamide 66 (PA66) nanocomposites was investigated. The nanocomposites were composed of PA66, melamine-modified layered silicate (MLS) as a nanofiller, and/or melamine cyanurate (MC). Samples of MLS with different dispersion states were obtained by changing the melt-mixing procedures for PA66, MLS and MC. X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal analysis, strength tests, cone calorimetry tests and UL 94 vertical burning tests were used to examine the effects of MLS on the morphology, mechanical properties and flame resistance performance of the materials. The data revealed a correlation between the dispersion state of the MLS layers and flame retardancy. The nanocomposite manufactured by one-stage kneading of a mixture of PA66, MLS and MC earned a UL 94 rating of V0. The flame retardancy of dripping particles during combustion was found to be due to uneven dispersion of MLS in the PA66 matrix.

A simple route has been adopted for the fabrication of polyurea using polycondensation of 4,4'-diphenylmethane diisocyanate and 1,4-phenylene diamine. Amalgamation of polystyrene, polyurea and functional graphene (F–G) yielded a series of nanocomposite foams. The morphological, electrical, mechanical, thermal, and flammability properties of materials were investigated and found to be dependent upon the intrinsic properties of graphene-based materials and their state of dispersion in matrix. Field emission scanning electron microscopy revealed a strong interaction between polystyrene/polyurea and functional graphene surface forming unique layered cellular structure. Mechanical results revealed a synergistic interaction between F–G and polystyrene/polyurea matrix providing a shielding mechanism against graphene layer damage during compression. The 10% thermal decomposition temperature of polystyrene/polyurea/F–G 1–5 foams measured was in the range of 432–470℃. UL 94 showed V-1 rating for polystyrene/polyurea foam, while polystyrene/polyurea/F–G 1–5 foams attained V-0 rating. Water absorption capacity was improved steadily with the time and was maximum after 96 h for polystyrene/polyurea/F–G 5 foam (4.53%). Functional graphene also produced excellent electrical conductivity improvement in polystyrene/polyurea/F–G 5 foam (101) relative to polystyrene/polyurea/F–G 1 foam (10−2) and neat polystyrene/polyurea foam materials (10−7).

Novel poly(ether–imide)/polyurethane (PEI/PU)-based nanocomposite and foamed systems reinforced with graphene nanoplatelet (GNP) were developed. Field emission scanning electron microscopy revealed hexagonal nanocelluar morphology due to fine interaction between PEI/PU and functional GNP. Compression strength and modulus values were raised up to 72.3 MPa and 27.3 GPa, respectively, for PEI/PU/GNP Foam 1, thus revealing a defensive role of GNP layer against damage. Tmax of PEI/PU/GNP Foam 0.1–1 was measured as 479–565°C. The UL 94 showed V-0 rating for nanocomposite, while foams attained V-1 rating. Water absorption capacity was improved steadily with time and was at maximum after 96 h for PEI/PU/GNP Foam 1 (12.3%).

A star-shaped aluminum dimethyl(2,2-dimethyl-1,3-propylene)bis(oxy)bicarbonylethyldiphos phinate (AlCP) was synthesized by esterifying reaction between 2-methy-2,5-dioxo-1,2-oxaphospholane (OP) and neopentyl glycol following by neutralizing with aluminum hydroxide. The structure and composition were confirmed with FTIR, 1H NMR, 31P NMR and X-ray fluorescent spectroscopy. AlCP begins to decompose at 370 °C, matching the initial decomposition temperature of PBT. It endows PBT with desired flame retardancy and anti-dripping property and shows good compatibility with PBT. When the total filler loading is kept at 17, 15–13 mass% AlCP combining with 2–4 mass% MC can make the PBT passing the UL 94 V0 rating and eliminating dripping. In addition, the AlCP has a little influence on the mechanical properties of PBT. The tensile strength and notched impact strength of PBT containing 17 mass% AlCP only reduce by 5.6 and 4 %, respectively, comparing to the pure PBT. The SEM photographs show that AlCP has a good compatibility with PBT. Microcombustion calorimeter, TG-FTIR and SEM results show that AlCP can depress the heating release and promote char forming during combustion and acts mainly in the condensed phase.

Flexible polyurethane foam is one of the most versatile materials used in upholstered products; however, untreated polyurethane flexible foams are prone to rapid fire growth. In order to overcome issues encountered by the addition of flame retardant additives during the manufacturing process, the sol–gel process was evaluated to make flexible polyurethane foams flame retardant. Various formulations using different catalysts and monomers were prepared and deposited on flexible polyurethane foams by an impregnation process. Coating morphology was assessed by scanning electron microscopy analyses to optimize the formulation and to obtain a homogenous crack-free coating. Flame retardant properties were measured by mass loss calorimeter and UL 94, and thermal degradation was evaluated by thermogravimetric analysis. Chemical and structural analyses were carried out using attenuated total reflectance Fourier transformed infra-red spectroscopy and electron probe microanalysis. It appears that when a mixture of an appropriate ratio of 3-amino propyl triethoxysilane and diethyl phosphate is prepared in association with tetraethoxysilicate and methyltriethoxysilicate and deposited on flexible polyurethane foam, the coating shows an intumescent behavior when exposed to a flame. The foam also self-extinguishes after 30 seconds of flame application during UL94 test and a 60% reduction of the peak of heat release rate is obtained under mass loss calorimeter conditions.

This study is focused on the characterization of polyethylene terephthalate (PET)/Styrene-Ethylene-Butylene-Styrene (SEBS)/Organomontmorillonite (OMMT) blends. SEBS-g-MA is used as compatibilizer and SEBS is the impact modifier at 30 %wt. The compounds were blended by twin-screw extruder and molded for test specimen by injection molding. The effect of OMMT types (Cloisite15A and Cloisite30B) and contents (1 and 3 %w/w) on properties of PET blends with SEBS and SEBS-g-MA were investigated. The PET composites incorporated with Cloisite15A had higher impact strength and %elongation at break whereas lower tensile strength than the one with Cloisite30B. Comparing with PET/SEBS/SEBS-g-MA blends, adding OMMT into PET/SEBS/SEBS-g-MA would increase thermal property. However, it had no significant changes with higher OMMT. %Crystallinity of PET would be increased with OMMT contents. PET/SEBS/SEBS-g-MA had lower %LOI but higher burning rate compared with PET. However, the addition of OMMT could improve flame retardant properties of PET blends. Addition of Cloisite15A and Cloisite30B into PET/SEBS/SEBS-g-MA increased %LOI. From UL 94 tests, polymer composites could be classified in HB class. The burning rate of polymer composites was decreased with increasing OMMT due to decomposition of OMMT act as a barrier to inhibit combustion.

Although widely used in industrial applications, epoxy resins generally display low toughness and high flammability. The use of phosphorus compounds can improve flame-retardant capabilities along with reducing mechanical properties. Herein, the novel flame-retardant additive of phosphorous-linked epoxidized vegetable oil (P-L-EVO) was fabricated from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and epoxidized vegetable oil through a ring opening reaction before applying it as additive for an epoxy/silica system. The silica was extracted from a rice husk using a combined approach of acid treatment and thermal treatment. Successful grafting and extraction reactions were confirmed using Fourier transform infrared analysis (FTIR) and nuclear magnetic resonace (NMR). The epoxy resin-based samples were cured with diethylenetriamine (DETA) hardener at ambient conditions. The influences of additives on the mechanical properties and flame-retardant capabilities were examined via tensile strength, impact strength, critical stress intensity (KIC), a cone calorimeter, the limited oxygen index (LOI), and the UL 94 vertical test. The epoxy sample with 20 wt.% silica and 10 wt.% of P-L-EVO (S20.10) reached the LOI value of 35.89 % and a V0 rating of UL94. Moreover, this combination improved the impact strength, tensile strength, and KIC by up to 90.16 %, 20.28 %, and 73.84 %, respectively in comparison with pristine epoxy sample (S00.00). The formation of a non-thermal decomposition char layer along with a release of flame-retardant radicals was considered the novel flame-retardant mechanism.

The development of poly(lactic acid) (PLA) composites having flame retardancy, tensile toughness and transparency is the state-of-the-art, which requires meticulous selection and combination of additives. To achieve this goal, an ionic liquid (IL) tetrabutylphosphonium tetrafluoroborate is synthesized and used as a synergist for ammonium polyphosphate (APP). Due to the high synergistic effect between them, only 1.5 wt% IL and 1.5 wt% APP (total amount of 3 wt%) can endow PLA with fire safety, i.e. limiting oxygen index (LOI) of 27.2, UL 94 V-0 rating and low heat release rate of 290 kW m−2. Besides, the elongation at break of PLA containing 3 wt% IL/APP increases from 8.5% of PLA to 204.6%. Meanwhile, the incorporation of IL/APP has tiny impact on the transparency of PLA. The PLA/IL/APP possessing toughness and flame retardancy shows great potentials in the fields of packaging, automotive and electronic and electric industry in the future.

A novel halogen-free flame retardant containing sulfonamide, 1,3,5,7-tetrakis (phenyl-4-sulfonamide) adamantane (FRSN) was synthesized and used for improving the flame retardancy of largely used polycarbonate (PC). The flame-retardant properties of the composites with incorporation of varied amounts of FRSN were analyzed by techniques including limited oxygen index, UL 94 vertical burning, and cone calorimeter tests. The new FR system with sulfur and nitrogen elements showed effective improvements in PC&rsquo, s flame retardancy: the LOI value of the modified PC increased significantly, smoke emission suppressed, and UL 94 V-0 achieved. Typically, the composite with only 0.08 wt% of FRSN added (an ultralow content) can increase the limiting oxygen index (LOI) value to 33.7% and classified as UL 94 V-0 rating. Furthermore, the mechanical properties and SEM morphology indicated that the FRSN has very good compatibility with PC matrix, which, in turn, is beneficial to the property enhancement. Finally, the analysis of sample residues after burning tests showed that a high portion of char was formed, contributing to the PC burning protection. This synthesized flame retardant provides a new way of improving PC&rsquo, s flame retardancy and its mechanical property.

High loading of flame retardants are usually required to prepare fire safety rigid polyurethane foam (RPUF), which often leads to deterioration of its mechanical properties. In this work, a silicone resin (poly-DDPM) was synthesized and coated on the surface of RPUF in association with expandable graphite (EG) via brush painting in order to improve its flame retardancy with minimal damage to the inherent mechanical property. The flammability characterization by limiting oxygen index (LOI), UL 94 and cone calorimeter tests revealed that the fire resistance of the foam samples was significantly improved by the presence of poly-DDPM/EG coating with an average add on of 8.5 mg/cm2. The LOI value was increased to 32.3 from 18, the UL 94 grade was upgraded to V-0, the peak heat release rate and the peak smoke release rate was reduced 55% and 59% respectively compared with that of the control RPUF sample. Additionally, the coated sample could not be ignited when it was exposed to a butane burner for 10 min. The compressive strength of the coated RPUF was impressively increased 10%. Furthermore, the fire resistance of the coating was durable under artificial harsh weather conditions. The poly-DDPM/EG coating adhered on the RPUF surface tightly, and transformed into expanded graphite flakes loaded nano-silica to achieve a protective char layer upon combustion. The demonstrated coated RPUF has great potential for commercial products.

First, Layered double hydroxide (LDH) was modified by toluene diisocyanate (TDI), 2-hydroxyethyl acrylate (HEA), and LDH-TDI-HEA was prepared. Then LDH-TDI-HEA was modified by vinyl triethoxysilane (VTES), and LDH-TDI-HEA-VTES composites were obtained. Finally, acrylate was modified by LDH-TDI-HEA-VTES, and flame retarded LDH-TDI-HEA-VTES-Acrylate composites were successfully synthesized by in situ polymerization. The structures of LDH, LDH-TDI-HEA, LDH-TDI-HEA-VTES and LDH-TDI-HEA-VTES-Acrylate composites were characterized by Fourier transform infrared spectra, X-ray diffraction, X-ray photoelectron spectroscopy and Scanning electron microscopic. The effect of LDH-TDI-HEA-VTES content on the thermal stability, mechanical properties, adhesion properties and flame retardant properties of LDH-TDI-HEA-VTES-Acrylate composites was studied. At the same time, the thermal stability, mechanical properties, adhesion properties and flame retardant properties of LDH-Acrylate composites and LDH-TDI-HEA-VTES-Acrylate composites were also studied. The experimental results showed that with the increasing of LDH-TDI-HEA-VTES content, the thermal stability, mechanical properties, flame retardant properties, and shear resistance of LDH-TDI-HEA-VTES-Acrylate composites were improved, while the tack and 180° peel strength decreased. When the content of LDH-TDI-HEA-VTES was 7 wt%, the LOI, after-flame time and the UL 94 grade of LDH-TDI-HEA-VTES-Acrylate composites were 27%, 0 s, and V-0, respectively. LDH-TDI-HEA-VTES-Acrylate Composites have good flame retardant properties. At the same time, the flame retardant mechanism of LDH-TDI-HEA-VTES composites was also analyzed.