Showing papers on "Cone calorimeter published in 2015"

A novel biobased epoxy resin with high mechanical stiffness and low flammability: synthesis, characterization and properties

Abstract: Exploring renewable biobased epoxy resins possessing intrinsic fire retardancy and high mechanical and thermal properties will greatly advance their potential to satisfy sustainability demands. Herein we develop a biobased route to synthesize a novel eugenol-based difunctional epoxy resin (TPEU-EP) with a full aromatic ester backbone. With 3,3′-diaminodiphenyl sulfone (33DDS) as the curing agent, TPEU-EP is compared with a standard bisphenol A epoxy resin (DGEBA) regarding their cure reactions and ultimate properties. The results show that TPEU-EP/33DDS expresses a higher reaction activation energy and a slower curing rate than DGEBA/33DDS. The isothermal cure reaction of TPEU-EP/33DDS is found to be autocatalytic. We accurately model the curing kinetics and elaborate on the related mechanisms based on the isoconversional analysis. The structure–property study reveals that TPEU-EP/33DDS manifests a 27%, 20% and 17% higher storage modulus (30 °C), Young's modulus and hardness than DGEBA/33DDS, respectively. TPEU-EP/33DDS displays a high glass temperature (168.4 °C) and thermal stability (up to 300 °C), and shows a much higher damping than DGEBA/33DDS in the glassy state. Moreover, compared with DGEBA/33DDS, TPEU-EP/33DDS shows a 130% and 3.3 increase in char yield (in N2) and limiting oxygen index and a 68% and 40% decrease in the heat release rate and total heat release (microscale combustion test), respectively. Impressively, TPEU-EP/33DDS can self-extinguish in a vertical burning test, and the cone calorimeter test further confirms that TPEU-EP/33DDS has a much improved flame retardancy with a notably lowered smoke production. In brief, TPEU-EP possesses good intrinsic flame retardancy, low smoke production, and excellent mechanical properties, showing high promise for application. Our contribution will open a new avenue to develop sustainable high-performance flame-retardant epoxy resins.

Synthesis of a Phosphorus/Nitrogen-Containing Additive with Multifunctional Groups and Its Flame-Retardant Effect in Epoxy Resin

Abstract: A novel additive, tri(phosphaphenanthrene-maleimide-phenoxyl)-triazine (DOPO-TMT), was successfully synthesized. The chemical structure was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance. DOPO-TMT was blended with epoxy resins to prepare flame-retardant thermosets. The flame-retardant properties were evaluated using limited oxygen index (LOI), vertical burning (UL94), and cone calorimeter tests. The results indicated that DOPO-TMT exhibited excellent flame-retardant effect. The flame-retardant mechanism was studied by thermogravimeric analysis (TGA), pyrolysis-gas chromatography/mass spectrometry, and thermogravimetric analysis/infrared spectrometry (TGA-FTIR) coupled with the morphology and chemical analysis of the char residues. The results disclosed that DOPO-TMT exerted biphase flame-retardant effect. In gaseous-phase, DOPO-TMT released phosphorus- and nitrogen-containing free radicals with quenching effect under thermal decomposition. The morphologies o...

Synthesis, Characterization, and Utilization of a Novel Phosphorus/Nitrogen-Containing Flame Retardant

Abstract: The novel phosphorus/nitrogen-containing flame retardant hexa(phosphaphenanthrene aminophenoxyl)cyclotriphosphazene (HPAPC), which contains phosphaphenanthrene [9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO)] and phosphazene (hexachlorocyclotriphosphazene) groups, was synthesized by the classic Atherton–Todd reaction, and its chemical structure was characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies. Poly(lactic acid) (PLA) composites containing HPAPC were prepared by melt blending, and their fire performance and thermal behaviors were investigated in terms of limiting oxygen index (LOI), vertical burning (UL-94), cone calorimeter tests, and thermogravimetric analysis (TGA). The LOI value could reach up to 34.7%, and UL-94 could pass V-0 for the PLA composite containing only 5 wt % HPAPC. TGA results showed that the char formation of PLA could be significantly improved by the presence of HPAPC. The evolved gas of the composite was analyzed by F...

Intumescent multilayer hybrid coating for flame retardant cotton fabrics based on layer-by-layer assembly and sol–gel process

Abstract: An intumescent coating composed of a nitrogen-modified silane hybrid (SiN) and phytic acid (PA) was deposited on cotton fabric through layer-by-layer assembly in order to reduce flammability. SiN was synthesized via a sol–gel process and characterized by 29Si-nuclear magnetic resonance. This intumescent coating system lowered the thermal stability of the cotton due to the catalyzed effect on degradation, but significantly improved the char formation. In a vertical flame test, fabrics coated with 15 bilayers (BLs) of SiN–PA extinguished the flame immediately upon removing the ignition source, while untreated cotton was completely burned out. Cone calorimeter data revealed that 15BL-coated cotton resulted in a 31% and 38% reduction in peak heat release rate and total heat release, respectively, relative to those of the uncoated control. This superior fire retardant performance is believed to be attributed to the formation of intumescent char layer on fibers that could effectively inhibit the oxygen and heat permeation when burning. In addition, as evidenced by thermogravimetric analysis-Fourier transform infrared spectroscopy results, the increased amount of inflammable gases and the decreased amount of flammable gases during the degradation of coated cotton fabrics was another important factor to improve the flame resistance. These results demonstrate that the combination of layer-by-layer assembly and sol–gel method will provide an effective alternative to current flame retardant treatments.

Efficient approach to improving the flame retardancy of poly(vinyl alcohol)/clay aerogels: incorporating piperazine-modified ammonium polyphosphate.

Abstract: Ammonium polyphosphates (APP) modified with piperazine (PA-APP) was used to improve the flame retardancy of poly(vinyl alcohol) (PVA)/montmorillonite (MMT) aerogels, which were prepared via an environmentally friendly freeze-drying method. The thermal stabilities of the samples were evaluated by thermogravimetric analysis (TG); the flammability behaviors of samples were investigated by limiting oxygen index (LOI), vertical burning test (UL-94) and cone calorimeter (CC) tests. TG test results showed that the 5% weight loss temperature (T5%) of PVA/MMT/PA-APP was 10 °C higher than that of PVA/MMT/APP. In combustion testing, all of PVA/MMT/PA-APP aerogels achieved V-0 ratings and have a higher LOI values than the unmodified PVA/MMT aerogel. Moreover, the aerogel with 1% PA-APP5, which means that the content of piperazine is 5% in PA-APP, decreased the cone calorimetry THR value to 5.71 MJ/m2, and increased the char residue to 52%. The compressive modulus of PVA/MMT/PA-APP was increased by 93.4% compared with...

An Effective Way To Flame-Retard Biocomposite with Ethanolamine Modified Ammonium Polyphosphate and Its Flame Retardant Mechanisms

Abstract: Biocomposite of wood flour (WF)/polypropylene (PP) composite (WPC) is not easily flame-retarded because of the different flame retardant mechanisms of PP and WF. In order to improve the flame retardancy of WPC, a single flame retardant of ammonium polyphosphate (APP) modified via ion exchange reaction with ethanolamine, which is named as ETA-APP, was used to prepare flame-retardant WPC. The flammability was investigated by limiting oxygen index (LOI), UL-94 vertical burning test, and cone calorimeter. The results show the flame retardant properties of the flame-retardant WPC are improved greatly. The limiting oxygen index is 43.0%, which is increased by 71.6% compared with that of WPC with the same content of APP. And the vertical burning test can pass UL-94 V-0 rating. The results of cone calorimeter test show that the heat release rate (HRR) and total heat release (THR) of the WPC with ETA-APP are decreased in comparison with WPC/APP. The flame-retardant mechanism of WPC/ETA-APP system was investigated ...

Effect of chlorinated phosphate ester based on castor oil on thermal degradation of poly (vinyl chloride) blends and its flame retardant mechanism as secondary plasticizer

Abstract: A novel flame retardant chlorinated phosphate ester based on castor oil (CPECO) was synthesized. Chemical structure of CPECO was characterized with FTIR, 1H NMR and 31P NMR. The application of CPECO as a secondary plasticizer for poly (vinyl chloride) (PVC) not only gained satisfied flame retardancy and mechanical properties, but also substituted for dioctyl phthalate (DOP) partly. Flame retardant properties of PVC plasticized with CPECO was explored with LOI tests, SEM, TGA, TGA-FTIR, TGA-MS and cone calorimeter tests. The results showed that LOI value of plasticized PVC blends could increase from 23.6% to 35.4%. TGA-FTIR and TGA-MS detected that the main pyrolysis products of PVC blends were H2O, HCl, CO2, CO and C6H6. Cone calorimeter tests showed that peak heat release (pHRR) of plasticized PVC blends could decreased from 379.00 to 289.00 kW m−2, total heat release (THR) decreased from 31.78 to 19.12 MJ m−2. The flame retardant mechanism of plasticized PVC blends could be concluded that phosphorous-containing components generated from pyrolysis of CPECO could promote formation of char residual. The char residual was blown by evolving gases which produced a foaming and expansion of the char layer. The carbonaceous char layer is effective to slow mass and heat transfer between the gas and condensed phases and to protect the underlying material from further combustion. The glass-transition temperature (Tg), mechanical properties of PVC blends and migration stability of CPECO were investigated.

Flammability and physical–mechanical properties assessment of wood treated with furfuryl alcohol and nano-SiO2

Abstract: Wood polymer nanocomposites were prepared via in situ polymerization of furfuryl alcohol (FA) using nano-SiO2 as the particulate phase within fast-growing poplar wood Different amounts of nano-SiO2 were mixed with an FA water solution, impregnated into the wood and then oven-heated to induce in situ polymerization Wood physical–mechanical properties, including dimensional stability, hydrophobic properties, surface hardness, compression strength, and modulus of elasticity, were significantly improved by furfurylation The addition of nano-SiO2 redeemed the reduction of modulus of rupture in FA-treated wood Scanning electron microscopy and Fourier transform infrared spectroscopy indicated that the nano-SiO2 was introduced into the poplar wood and fixed on the cell wall with FA The contact angle analysis showed FA and 05–10 % nanoparticles jointly affected the hydrophobic property of the wood surface In addition, the cone calorimeter results showed an obviously improved flammability and thermal stability of treated wood at 20 % nano-SiO2 addition

Smoke suppression properties of carbon black on flame retardant thermoplastic polyurethane based on ammonium polyphosphate

Abstract: In this paper, fumed silica has been used as smoke suppression and flame-retardant synergism in thermoplastic polyurethane (TPU) composites based on ammonium polyphosphate (APP) And, the synergistic smoke suppression property and flame-retardant effect of fumed silica in flame-retardant TPU composites are mainly intensively investigated by several methods, including smoke density test (SDT), cone calorimeter test (CCT), scanning electron microscopy (SEM), limiting oxygen index, and thermogravimetric analysis The results of SDT show that fumed silica can significantly decrease smoke production of flame-retardant TPU composites The results of CCT present that the addition of fumed silica can effectively reduce smoke production rate, total smoke release, smoke factor, heat release rate, and mass loss in the combustion process of flame-retardant TPU composites The SEM results show that fumed silica can improve the quality of char residue after cone calorimeter test All the results show that fumed silica is an effective smoke suppression agent and a good flame-retardant synergism with APP in TPU composites

Natural fibers: Their composites and flammability characterizations

Abstract: The concept of green composites offers challenges to the designers in many aspects, which warrants the identification of more environment-friendly resources. In this regard, replacing synthetic fibers with natural ones in composite materials has to play a major role in manufacturing engineering. The advantages, such as low cost, low density, high toughness, relatively high specific strength properties, low abrasiveness, low energy consumption in fabrication, and CO2 neutrality of some natural fibers, provide the researchers incentives to use these materials in new developments. Most recent research efforts have removed many fiber–matrix compatibility problems; however, poor thermal stability is a major drawback in using these materials, especially in transportation and aerospace applications. Generally, natural fibers are considered as heat sources in composites. If the fiber cellulose content is high, it tends to increase the flammability due to high levels of levoglucosan, but the amount of lignin content in the fibers leads to char formation after initial ignition and provides a thermal barrier. This phenomenon can be used to control the fire growth, by selecting good combination of materials and obtaining effective homogeneous composites under suitable processing conditions. This chapter initially gives a brief account of various types of natural fibers, suitable matrix reinforcements, general methodologies for flammability measurements, and finally describes some specific flame retardance results using two types of natural fibers, namely plant-based kenaf and animal-based wool fibers. The effects of various intumescent ammonium polyphosphate (APP)-based fire retardants are discussed. It is clear that some statistical analysis is necessary to get the necessary fire characteristics without sacrificing too much of mechanical performance. The fire characterization has been carried out through horizontal and vertical burn tests, and by studying peak heat release rate, total heat release, and smoke constituents, using a cone calorimeter.

Synergistic effect of graphene and an ionic liquid containing phosphonium on the thermal stability and flame retardancy of polylactide

Abstract: A series of nanocomposites based on the biodegradable plastic, polylactide (PLA), have been prepared by melt-blending with graphene (Gra) and ionic liquid containing phosphonium ([PCMIM]PF6, IL) surface-functionalized graphene (GIL) The morphology, mechanical properties, thermal stability and burning behaviour of the composites were investigated by Field Emission Scanning Electron Microscopy (FESEM), tensile test, impact test, Thermogravimetric Analysis (TGA), Limiting Oxygen Index (LOI), UL-94 test and Cone Calorimeter Test (CCT), respectively The surface morphology and chemical structure of the char residues were explored by FESEM and Raman spectroscopy It is confirmed that the fire-retardant performance of the PLA/GIL composites was significantly improved compared to PLA/IL and PLA/Gra; the CCT data showed a reduction in heat release rate and total heat released with increase of the char residue from the TGA results It revealed that the catalytic charring effect of the ionic liquid, the physical isolating effect of graphene, and the combined effect of both the ionic liquid and graphene (forming continuous and compact char layers) were very efficient in improving the flame retarding properties of PLA/GIL nanocomposites

Halogen-free fire retardant styrene–ethylene–butylene–styrene-based thermoplastic elastomers using synergistic aluminum diethylphosphinate–based combinations:

Abstract: Multicomponent flame retardant systems containing aluminum diethylphosphinate in thermoplastic styrene–ethylene–butylene–styrene elastomers are investigated (oxygen index, UL 94, cone calorimeter, and mechanical testing). Solid-state nuclear magnetic resonance, scanning electron microscopy, and elemental analysis illuminate the interactions in the condensed phase. Thermoplastic styrene–ethylene–butylene–styrene elastomers are a challenge for flame retardancy (peak heat release rate at 50 kW m−2 > 2000 kW m−2, oxygen index = 17.2 vol%, no UL-94 horizontal burn rating) since it burns without residue and with a very high effective heat of combustion. Adding aluminum diethylphosphinate results in efficient flame inhibition and improves the reaction to small flame, but it is less effective in the cone calorimeter. Its efficacy levels off for amounts >∼25 wt%. As the most promising synergistic system, aluminum diethylphosphinate/melamine polyphosphate was identified, combining the main gas action of aluminum di...

Combustion behaviors of cotton fabrics treated by a novel guanidyl- and phosphorus-containing polysiloxane flame retardant

Abstract: A novel flame-retardant agent, nitrogen- and phosphorus-containing polysiloxane [(IB-co-N-MDPA)PDMS] was synthesized, and it was employed on cotton fabrics. Cone calorimeter testing showed that the treated cotton fabric with (IB-co-N-MDPA)PDMS became less flammable with longer time to ignition and lower value of HRR, THR, EHC and mass loss. Thermogravimetric analysis demonstrated that (IB-co-N-MDPA)PDMS improved the thermal and thermo-oxidative stability of cotton fabric with fewer flammable volatiles, and more char is produced during combustion. Scanning electron microscopy showed that the surface of treated cotton fabric after combustion was covered by a compact char layer which indicated that (IB-co-N-MDPA)PDMS favored the formation of char as evidenced by the FTIR of residues. Furthermore, EDS analysis results demonstrated that the concurrent presence of Si and P in flame retardant effectively enhance the flame retardancy of cotton fabric with the remarkable amount of Si and P elements that were still present on the surface of fibers after combustion.