Effect of cloisite 30B clay and sisal fiber on dynamic mechanical and fracture behavior of unsaturated polyester toughened epoxy network

This study examined the dynamic mechanical properties of sisal fiber reinforced unsaturated polyester (UP) toughened epoxy nanocomposites. The chemical structures changes in Epoxy, UP and UP toughened epoxy (Epoxy/UP) systems were characterized by Proton Nuclear magnetic resonance (¹HNMR) spectroscopy. The morphological alterations of the nanocomposites were analyzed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The untreated, chemically treated fibers, nanoclays, and the fiber reinforced Epoxy/UP nanocomposites were confirmed by FTIR spectrometer. The obtained mechanical results showed that alkali‐silane treated fibers improve the tensile strength (96%) and flexural strength (60%) of the Epoxy/UP nanocomposite than that of Epoxy/UP blend due to the strong interfacial bonding between the sisal fiber and matrix. The fracture toughness (K_IC) and fracture energy (G_IC) of treated sisal fiber reinforced DGEBA/UP/C30B nanocomposites found to be higher than that of untreated sisal fiber nanocomposites. The dynamic mechanical analysis (DMA) reveals that the fiber reinforced Epoxy/UP nanocomposites contains 30 wt% treated fiber and 1 wt% nanoclays, exhibits the highest storage modulus and better glass transition temperature (T_g) among the other kind of systems. The surface morphology of the fibers, fractured surface of the resins and composites were confirmed by scanning electron microscope (SEM). POLYM. COMPOS., 37:2832–2846, 2016. © 2015 Society of Plastics Engineers     

Unsaturated polyester‐toughened epoxy composites: Effect of sisal fiber on thermal and dynamic mechanical properties

In the present study, the mechanical and thermal properties of sisal fiber‐reinforced unsaturated polyester (UP)‐toughened epoxy composites were investigated. The sisal fibers were chemically treated with alkali (NaOH) and silane solutions in order to improve the interfacial interaction between fibers and matrix. The chemical composition of resins and fibers was identified by using Fourier‐transform infrared spectroscopy. The UP‐toughened epoxy blends were obtained by mixing UP (5, 10, and 15 wt%) into the epoxy resin. The fiber‐reinforced composites were prepared by incorporating sisal fibers (10, 20, and 30 wt%) within the optimized UP‐toughened epoxy blend. Scanning electron microscopy was used to analyze the morphological changes of the fibers and the adhesion between the fibers and the UP‐toughened epoxy system. The results showed that the tensile and flexural strength of (alkali‐silane)‐treated fiber (30 wt%) ‐reinforced composites increased by 83% and 55%, respectively, as compared with that of UP‐toughened epoxy blend. Moreover, thermogravimetric analysis revealed that the (alkali‐silane)‐treated fiber and its composite exhibited higher thermal stability than the untreated and alkali‐treated fiber systems. An increase in storage modulus and glass transition temperature was observed for the UP‐toughened epoxy matrix on reinforcement with treated fibers. The water uptake behavior of both alkali and alkali‐silane‐treated fiber‐reinforced composites is found to be less as compared with the untreated fiber‐reinforced composite. J. VINYL ADDIT. TECHNOL., 23:188–199, 2017. © 2015 Society of Plastics Engineers     

Nanoclay and long-fiber-reinforced composites based on epoxy and phenolic resins

In this study, high-performance thermoset polymer composites are synthesized by using both long fibers and nanoclays. Epoxy and phenolic resins, the two most important thermoset polymers, are used as the polymer matrix. The hydrophobic epoxy resin is mixed with surface modified nanoclay, while the hydrophilic phenolic resin is mixed with unmodified raw nanoclay to form nanocomposites. Long carbon fibers are also added into the nanocomposites to produce hybrid composites. Mechanical and thermal properties of synthesized composites are compared with both long-fiber-reinforced composites and polymer- layered silicate composites. The optimal conditions of sample preparation and processing are also investigated to achieve the best properties of the hybrid composites. It is found that mechanical and thermal properties of epoxy and phenolic nanocomposites can be substantially improved. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

An investigation of sound absorption coefficient on sisal fiber poly lactic acid bio‐composites

In this research, the mechanical, acoustical, thermal, morphological, and infrared spectral properties of untreated, heat and alkaline‐treated sisal fiber‐reinforced poly‐lactic‐acid bio‐composites were analyzed. The bio‐composite samples were fabricated using a hot press molding machine. The properties mentioned above were evaluated and compared with heat‐treated and alkaline‐treated sisal fibers. Composites with heat‐treated sisal fibers were found to exhibit the best mechanical properties. Thermo‐gravimetric analysis (TGA) was conducted to study the thermal degradation of the bio‐composite samples. It was discovered that the PLA‐sisal composites with optimal heat‐treated at 160°C and alkaline‐treated fibers possess good thermal stability as compared with untreated fiber. The results indicated that the composites prepared with 30wt % of sisal had the highest sound absorption as compared with other composites. Evidence of the successful reaction of sodium hydroxide and heat treatment of the sisal fibers was provided by the infrared spectrum and implied by decreased bands at certain wavenumbers. Observations based on scanning electron microscopy of the fracture surface of the composites showed the effect of alkaline and heat treatment on the fiber surface and improved fiber‐matrix adhesion. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42470.     

Thermo mechanical behaviour of unsaturated polyester toughened epoxy–clay hybrid nanocomposites

The intercrosslinked networks of unsaturated polyester (UP) toughened epoxy–clay hybrid nanocomposites have been developed. Epoxy resin (DGEBA) was toughened with 5, 10 and 15% (by wt) of unsaturated polyester using benzoyl peroxide as radical initiator and 4,4′-diaminodiphenylmethane as a curing agent at appropriate conditions. The chemical reaction of unsaturated polyester with the epoxy resin was carried out thermally in presence of benzoyl peroxide-radical initiator and the resulting product was analyzed by FT-IR spectra. Epoxy and unsaturated polyester toughened epoxy systems were further modified with 1, 3 and 5% (by wt) of organophilic montmorillonite (MMT) clay. Clay filled hybrid UP-epoxy matrices, developed in the form of castings were characterized for their thermal and mechanical properties. Thermal behaviour of the matrices was characterized by differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Mechanical properties were studied as per ASTM standards. Data resulted from mechanical and thermal studies indicated that the introduction of unsaturated polyester into epoxy resin improved the thermal stability and impact strength to an appreciable extent. The impact strength of 3% clay filled epoxy system was increased by 19.2% compared to that of unmodified epoxy resin system. However, the introduction of both UP and organophilic MMT clay into epoxy resin enhanced the values of mechanical properties and thermal stability according to their percentage content. The impact strength of 3% clay filled 10% UP toughened epoxy system was increased by 26.3% compared to that of unmodified epoxy system. The intercalated nanocomposites exhibited higher dynamic modulus (from 3,072 to 3,820 MPa) than unmodified epoxy resin. From the X-ray diffraction (XRD) analysis, it was observed that the presence of d ₀₀₁ reflections of the organophilic MMT clay in the cured product indicated the development of intercalated clay structure which in turn confirmed the formation of intercalated nanocomposites. The homogeneous morphologies of the UP toughened epoxy and UP toughened epoxy–clay hybrid systems were ascertained from scanning electron microscope (SEM).     

Investigation on phosphorus halogen‐free flame‐retardancy systems in short glass fiber‐reinforced PC/ABS composites under rapid thermal cycle molding process condition

In this study, standard test specimens with flame‐retarded short glass fiber‐reinforced PC/ABS materials were fabricated under rapid thermal cycle injection molding condition by selecting a potassium perfluorobutane sulfonate flame retardant specially used for PC, FR2025, and two kinds of aryl phosphorus halogen‐free flame retardants, UN707 and PX‐220. The flame‐retardancy effect of the above different flame retardants on the studied systems was compared through combustion tests of the specimens. Meanwhile, the thermal and mechanical properties of flame‐retarded composites were studied by using the thermogravimetry analysis, dynamic mechanical thermal analysis (DMTA), and universal testing machine. The results show that the “candlewick effect” of fibers exacerbates the fire behavior of composites. With the increase of the aryl phosphorus halogen‐free flame retardants, the flame‐retardancy effect of composites is obviously improved, and the maximum thermal degradation rate of composites is significantly decreased. The UL94 combustion rating is improved, and the time of residual flame is substantially reduced with the increase of PC content under the same content of flame retardant. The DMTA results show that the flame retardants have a reinforcement action on PC/ABS matrix. However, the macroscopic mechanical properties are slightly decreased in the glass fiber‐reinforced composites because of the destructive effect of the flame retardants on the interface compatibility between matrix and fibers; the scanning electron microscopic micrographs of tensile fracture fully prove this action mechanism of flame retardants. In addition, the addition of toughener and antidripping additive significantly affects the flame retardancy and mechanical properties of composites. POLYM. COMPOS., 36:1653–1663, 2015. © 2014 Society of Plastics Engineers     

Flame retardant polyurethane elastomer nanocomposite applied to coal mines as air‐leak sealant

Polyurethane elastomer (PUE) was firstly applied to mining coal roadway as air‐leak sealant. It is very important for air‐leak sealants to possess the super mechanical properties and good flame retardant performance when applied to the coal‐rock mass with cracks. The reinforced and toughened PUE nanocomposites were obtained by adding surface modified TiO₂ and SiO₂ nanoparticles. The modified PUE was characterized in terms of morphology, structure, and thermal stability by field‐emission scanning electron microscopy (FESEM), X‐ray diffraction (XRD), infrared spectroscopy (IR), and thermogravimetric analysis (TGA). Its flame‐retardant performance and mechanical properties were also tested. The results showed that the surface modified nanoparticles were uniformly dispersed in the PUE matrix and enhanced its thermal stability and flame retardant performance. The dual effects of uniform dispersion of nanoparticles and hydrogen bonding between nanoparticles and PUE improved the mechanical properties of the composites. The PUE modified by nanoparticles was successfully applied to coal mines and showed great air‐leak sealing effect. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

A comparison of partially acetylated nanocellulose,nanocrystalline cellulose,and nanoclay as fillers for high‐performance polylactide nanocomposites

Partially acetylated cellulose nanofibers (CNF) were chemically extracted from sisal fibers and the performance of those CNF as nanofillers for polylactide (PLA) for food packaging applications was evaluated. Three PLA nanocomposites; PLA/CNF (cellulose nanofibers), PLA/CNC (nanocrystalline cellulose), and PLA/C30B (Cloisite^TM 30B, an organically modified montmorillonite clay) were prepared and their properties were evaluated. It was found that CNF reinforced composites showed a larger decrease on oxygen transmission rate (OTR) than the clay‐based composites; (PLA/CNF 1% nanocomposite showed a 63% of reduction at 23°C and 50% RH while PLA/C30B 1% showed a 26% decrease) and similar behavior on terms of water vapor barrier properties with 46 and 43%, respectively of decrease on water vapor transmission rate at 23°C and 50% RH (relative humidity). In terms of mechanical and thermomechanical properties, CNF‐based nanocomposites showed better performance than clay‐based composites without affecting significantly the optical transparency. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43257.     

Ethylene vinyl acetate copolymer nanocomposites based on (un)modified sepiolite: Flame retardancy,thermal, and mechanical properties

Flame retardant ethylene‐vinyl acetate (EVA) nanocomposites were prepared by melt blending using unmodified and modified sepiolite. Modification process of sepiolite was carried out by using 3‐aminopropyltrimethoxysilane in water/ethanol medium. Thermal, mechanical, and flame retardancy properties of the prepared nanocomposites were evaluated and compared with each other. X‐ray diffraction and scanning electron microscopy indicated that sepiolite fibers are well‐dispersed in EVA matrix. By the addition of (un)modified sepiolite, both flame retardancy and thermal stability characteristics first improved, and then deteriorated, indicating a direct relationship between these properties. It was also found that sepiolite protects carbonyl groups of EVA from further degradation. Most interestingly, a simultaneous increase in both ductility and toughness was observed in the prepared composites. Whatever the evaluated properties were, whether the mechanical, thermal, or flame retardancy, the improved properties were more remarkable when modified sepiolite was utilized. POLYM. COMPOS., 38:1302–1310, 2017. © 2015 Society of Plastics Engineers     

Flexible and flame resistant poly(lactic acid)/organomontmorillonite nanocomposites

The PLA/OMMT nanocomposites were produced using a melt compounding technique with isopropylated triaryl phosphate ester flame retardant (FR; 10–30 parts per 100 resin). The flammability of the PLA/OMMT composites was evaluated with an Underwriter Laboratory (UL‐94) vertical burning test, and their char morphology was studied using scanning electron microscopy (SEM). The thermal properties of the PLA/OMMT were characterized with a thermogravimetric analyzer (TGA) and a differential scanning calorimeter (DSC). The thermal analyses showed that adding FR reduced the decomposition onset temperature (T_o) of PLA/OMMT. Both PLA/OMMT/FR20 and PLA/OMMT/FR30 showed excellent flame retardant abilities, earning a V‐0 rating during the UL‐94 vertical burning test. A compact, coherent and continuous protective char layer was formed in the PLA/OMMT/FR nanocomposites. Additionally, the DSC results indicated that the flexibility of the PLA/OMMT composites increased after adding FR due to the FR‐induced plasticization. The impact strength of PLA/OMMT was greatly increased by the addition of FR. Flexible PLA nanocomposites with high flame resistance were successfully produced. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41253.     

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

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

Evaluation of the mechanical properties of sisal–polyester composites as a function of the polyester matrix formulation

In this work a comparative study on the impact and tensile properties of polyester/sisal fiber reinforced composites was undertaken. The polyester matrix was used bare and modified with: (1) a silane coupling agent; (2) a flame retardant system; and (3) a blend of the silane agent and the flame retardant system. The experimental results show that the flame retardant acts as a particulate reinforcement to the polyester matrix and the silane coupling agent acts as a plasticizer. The simultaneous addition of these two compounds to the polyester resin tended to decrease the performance of the composites. The results obtained show that strength or toughness could be tailored, and although none of the composites manufactured with the modified polyester matrices showed a significant improvement on the fiber–matrix interface strength, a better compromise between impact and tensile properties was obtained with the silane modified matrix. The critical fiber volume fraction was also evaluated and shown to be less than 10% for the sisal–polyester composite investigated here. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1209–1217, 2004     

Effects of ammonium polyphosphate and triphenyl phosphate on the flame retardancy,thermal, and mechanical properties of glass fiber–reinforced PLA/PC composites

The purpose of this study is to increase of the flammability properties of the glass fiber (GF)–reinforced poly (lactic acid)/polycarbonate (PLA/PC) composites. Ammonium polyphosphate (APP) and triphenyl phosphate (TPP) were used as flame retardants that are including the organic phosphor to increase flame retardancy of GF‐reinforced composites. APP, TPP, and APP‐TPP mixture flame retardant including composites were prepared by using extrusion and injection molding methods. The properties of the composites were determined by the tensile test, limiting oxygen index (LOI), differential scanning calorimetry (DSC), and heat release rate (HRR) test. The minimum T_g value was observed for the TPP including PLA/PC composites in DSC analysis. The highest tensile strength was observed in GF‐reinforced PLA/PC composites. In the LOI test, GF including composite was burned with the lowest concentration of oxygen, and burning time was the longest of this composite. However, the shortest burning time was obtained by using the mixture flame retardant system. The flame retardancy properties of GF‐reinforced PLA/PC composite was improved by using mixture flame retardant. When analyzed the results of HRR, time to ignition (TTI), and mass loss rate together, the best value was obtained for the composite including APP.     

The flame‐retardance polylactide nanocomposites with nano attapulgite coated by resorcinol bis(diphenyl phosphate)

The nano attapulgite (ATP) coated by flame‐retardant resorcinol bis(diphenyl phosphate) (RDP) was prepared, and the modification effects were analyzed by scanning electron microscopy plus energy dispersive spectrometer, Fourier‐transform infrared spectra, the contact angles, and thermal gravimetry analysis. The results showed that RDP was adsorbed and formed a uniform layer on the surface of nano ATP with a content of about 25 wt%. The prepared polylactide (PLA) nanocomposites with the RDP‐coated nano ATP showed good mechanical properties, and the tensile strength of the nanocomposites containing 30 wt% of the RDP‐coated nano ATP reached 76.9 MPa in comparison with 66.2 MPa of pure PLA. The limiting oxygen index of the prepared PLA composites containing 30 wt% of the RDP‐coated nano ATP was about 24.5% and V‐0 rating was attained compared with 20.5% and with no rating of pure PLA. After the burning of the flame‐retardant PLA composites, a compact and coherent charred layer was formed; the flame‐retardance mechanism is discussed in detail. J. VINYL ADDIT. TECHNOL., 22:506–513, 2016. © 2015 Society of Plastics Engineers     

Preparation and characterization of new flame retardant polyurethane composite and nanocomposite

In this work, a new flame retardant additive [2‐phenyl‐1,3,2 oxazaphospholidine 2‐oxide (POPO)] containing phosphorus and nitrogen is synthesized using phenyl phosphonic dichloride, ethanol amine, and copper (II) chloride, as catalyst. POPO is characterized by ¹H‐NMR, ¹³C‐NMR, and ³¹P‐NMR and used as additive in polyurethane composites. Moreover, two commercial flame retardant additives [tricalcium diphosphate and hexabromocyclododecane (HBCD)] as well as nanoclay are used to compare flame retardancy of the synthesized additive. Limited oxygen index (LOI) and time burning (flammability test) of polyurethane composites and nanocomposites are evaluated. The results of the LOI test demonstrate that POPO is an excellent flame retardant additive and can be used to improve flame retardancy of polyurethane composites. In addition, increasing the additive content leads to an improvement of the flame retardancy of the samples. The LOI results show, however, that POPO is a good flame retardant, but the high synthesis cost of this flame retardant is a major disadvantage. Thermogravimetric analysis results show that using POPO in polyurethane matrices leads to low thermal stability and high char residue. Moreover, the nanocomposite has better thermal stability than the other samples. Scanning electron microscope micrographs have been used to evaluate the char residue of the samples. These micrographs indicate that POPO is an intumescent flame retardant and HBCD follows a nonintumescent mechanism. Exfoliated/intercalated structures have been shown for nanocomposites by transmission electron microscope. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Unsaturated polyester–poly(ε‐caprolactone) hybrid nanocomposites: Thermal–mechanical properties

This paper reports on the thermal behavior and mechanical properties of nanocomposites based on unsaturated polyester resin (UP) modified with poly(ɛ‐caprolactone) (PCL) and reinforced with an organically modified clay (cloisite 30B). To optimize the dispersion of 30B and the mixing of PCL in the UP resin, two different methods were employed to prepare crosslinked UP–PCL‐30B hybrid nanocomposites. Besides, two samples of poly(ɛ‐caprolactone) of different molecular weight (PCL2: M_n = 2.10³g.mol⁻¹ and PCL50: M_n = 5.10⁴g.mol⁻¹) were used at several concentrations (4, 6, 10 wt%). The 30B concentration was 4 wt% in all the nanocomposites. The morphology of the samples was studied by scanning electron microscopy (SEM). The analysis of X‐ray patterns reveals that intercalated structures have been found for all ternary nanocomposites, independently of the molecular weight, PCL concentration and the preparation method selected. A slight rise of the glass transition temperature, T_g, is observed in UP/PCL/4%30B ternary nanocomposites regarding to neat UP. The analysis of the tensile properties of the ternary (hybrid) systems indicates that UP/4%PCL2/4%30B nanocomposite improves the tensile strength and elongation at break respect to the neat UP while the Young modulus remains constant. POLYM. COMPOS., 35:827–838, 2014. © 2013 Society of Plastics Engineers     

氢氧化铝含量对聚酯/玻璃纤维复合材料阻燃性能和力学性能的影响

通过熔融混炼和模压成型工艺,制备含氢氧化铝(ATH)的干式不饱和聚酯/玻璃纤维(UP/GF)共混复合材料。采用氧指数法(LOI)和垂直燃烧法(UL94)表征UP/GF复合材料的阻燃性能,采用DMA研究UP/GF复合材料的动态力学性能,采用静态力学方法研究UP/GF复合材料的冲击和弯曲性能。结果表明:UP复合材料中,ATH的含量在25%时,既能够满足V—0级阻燃级别,氧指数值为28.7%,且材料的冲击和弯曲强度分别为5.66kJ/m2和58.72MPa,同时也有较好的动态力学性能。     

Synergistic effect of organo‐montmorillonite on intumescent flame retardant ethylene‐octene copolymer

Nanocomposite of thermoplastic elastomer ethylene‐octene copolymer/maleated ethylene‐octene (POE/POE‐g‐MAH) with organo‐montmorillonite (OMMT, 11 wt %) as masterbatch have been obtained by melt blending and it has been characterized by transmission electron microscopy (TEM). Flame retardant POE/POE‐g‐MAH/OMMT/ammonium polyphosphate‐pentaerythritol (APP‐PER) (an intumescent flame retardant with 75 wt % ammonium polyphosphate and 25 wt % pentaerythritol) composites were prepared by using melting processing to study their structures, flame‐retardancy, thermal, and mechanical properties. TEM showed exfoliated structures throughout POE/POE‐g‐MAH/OMMT masterbatch and POE/POE‐g‐MAH/OMMT/APP‐PER nanocomposites. Synergistic effect was observed between OMMT and APP‐PER resulting in significant improvements on thermal stability, flame‐retardancy and mechanical properties in the POE/POE‐g‐MAH/OMMT/APP‐PER nanocomposites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Flame‐retardant materials: synergistic effect of halloysite nanotubes on the flammability properties of acrylonitrile–butadiene–styrene composites

Novel well‐dispersed nanocomposites of halloysite nanotubes and acrylonitrile–butadiene–styrene were prepared. The fire retardancy and thermal stability of these new nanocomposites were improved. A synergistic effect was observed between the halloysite nanotubes and an intumescent flame‐retardant system consisting of ammonium polyphosphate, melamine polyphosphate and pentaerythritol in the acrylonitrile–butadiene–styrene composites. The incorporation of the intumescent flame‐retardant material into the halloysite–polymer nanocomposite system also improved the thermal stability and reduced the peak heat release rate by up to 56.2%, and it significantly reduced the emission of CO and CO₂ gases. The morphology and dispersion of the halloysite nanotubes were characterized using scanning and transmission electron microscopy. The thermal stability and flammability properties were investigated using thermogravimetric analysis and cone calorimeter tests. © 2013 Society of Chemical Industry     

Flame retardancy and mechanical properties of a novel intumescent flame‐retardant unsaturated polyester

A novel macromolecular intumescent flame retardant (MIFR) was synthesized. Unsaturated polyester (UP) filled with MIFR as flame‐retardant additive was prepared. The effects of MIFR on properties such as tensile strength, impact strength, flame‐retardant behavior, thermal stability, and morphology of char were studied. Its flammability and burning behavior were characterized by UL 94 and limiting oxygen index. Twenty‐four percent of MIFR were doped into UP to get 30.5% of limiting oxygen index and UL 94 V‐0, whereas its tensile strength and the impact strength were decreased by only 7.2% and 7.0%, respectively. Activation energy for the decomposition of samples was obtained by using the Kissinger equation. The results for UP containing MIFR, compared with UP, show that the weight loss, thermal stability, and the decomposition activation energy decreased, and the char yield increased, showing that MIFR can catalyze decomposition and carbonization of UP to form an effective charring layer to protect the underlying substrate. J. VINYL ADDIT. TECHNOL., 22:350–355, 2016. © 2014 Society of Plastics Engineers