Synergistic fire safety improvement between oyster shell powder and ammonium polyphosphate in TPU composites

In this article, oyster shell powder (OSP) was used as fire safety agent with ammonium polyphosphate (APP) in thermoplastic polyurethane (TPU) composites. The synergistic fire safety improvement between OSP and APP was intensively investigated using limiting oxygen index (LOI), UL‐94, smoke density test (SDT), and cone calorimeter test (CCT). There is a good synergistic effect of reducing the fire hazards when OSP was used with APP in TPU. The peak heat release rate (pHRR) of the sample with 2.0‐wt% OSP and 8.0‐wt% APP decreased to 86.8 kW/m² from 175.7 kW/m² of the sample with only 10.0‐wt% APP. The SDT results showed that the luminous flux of sample OSP2/APP8 was up to 28.9% at the end of experiment with flame, which was much higher than that of pure TPU (1.5%). The thermal stability and thermal decomposition of TPU composites were characterized by thermogravimetric analysis/Fourier infrared spectrum analysis (TG‐IR). The result revealed the inert gasses (including CO₂ and water vapor) produced by the reaction between OSP and APP. A char formed on the surface of composites, hindered the flame spread, reduced the release of combustible gas, and restricted the precursor of smoke into combustion zone.     

Influence of water content on failure of phenolic composites in fire

This paper evaluates the structural performance of flame resistant phenolic matrix composites exposed to fire. Experimental fire tests were performed on a glass-phenolic composite under combined static loading and one-sided radiant heating. The reduction to the tension and compression failure strengths of the phenolic composite was measured in these tests for heat flux conditions ranging from 10 kW/m² (∼225 °C) to 75 kW/m² (∼700 °C). It was discovered that the failure strengths of the phenolic composite decreased rapidly in the event of fire, particularly under compressive loading when failure occurred more rapidly than under tensile loading. The phenolic composite, despite having high flame resistance, loses strength more rapidly and fails sooner than a more flammable vinyl ester composite. The study shows that greater flammability resistance does not necessarily result in better structural performance in fire. The poor structural performance of the phenolic composite was due to explosive delamination damage and cracking caused by vaporisation of water in the matrix phase. It is shown that removing water from phenolic composites by natural or artificial ageing reduces the incidence of delamination cracking and thereby improves the materials' structural performance in fire. It is concluded that phenolic composites do not provide good structural performance in fire, even though they have low flame and smoke properties. However, reducing the water content in the matrix phase below about 10% can greatly improve the structural performance of phenolic composites during fire.     

Vanillin‐derived phosphorus‐containing compounds and ammonium polyphosphate as green fire‐resistant systems for epoxy resins with balanced properties

Flame retardants from vanillin when utilized together with ammonium polyphosphate (APP) yield excellent synergistic flame retardancy toward epoxy resins. Bisphenol A epoxy resins have been widely used due to their excellent mechanical properties, chemical resistance, electrical properties, adhesion, etc., while they are flammable. Environment‐friendly and bio‐based flame retardants have captured increasing attention due to their ecological necessity. In this paper, 3 bio‐based flame retardants were synthesized from abundant and more importantly renewable vanillin, and their chemical structures were determined by ¹H NMR and ¹³C NMR. They were used together with APP (an environment‐friendly commercial flame retardant) to improve the fire resistance of bisphenol A epoxy resin. With the addition APP content of 15 phr, the modified bisphenol A epoxy resin could reach UL‐94V0 rating during vertical burning test and limit oxygen index values of above 35%, but reducing APP content to 10 phr, the flame retardancy became very poor. With the total addition content of 10 phr, the epoxy resins modified by 7 to 9 phr APP and 1 to 3 phr bio‐based flame retardants with epoxy groups or more benzene rings showed excellent flame retardancy with UL‐94V0 rating and limit oxygen index values of around 29%. The T_gs of the epoxy resins could be remained or even increased after introducing bio‐based flame retardants, as the control; those of APP alone‐modified epoxy resins compromised a lot. The green synergistic flame‐retardant systems have a great potential to be used in high‐performance materials.     

Simultaneous enhancement of thermal conductivity and flame retardancy for epoxy resin thermosets through self‐assemble of ammonium polyphosphate surface with graphitic carbon nitride

Conferring the flame retardant performance and thermal conductivity simultaneously for epoxy resin (EP) thermosets was significant for fire safety and thermal management applications of electrical and electronic devices. Herein, the graphitic carbon nitride (g‐C₃N₄) with desired amount was assembled on the surface of ammonium polyphosphate (APP), and the obtained APP/g‐C₃N₄ (CN‐APP) was characterized and confirmed by X‐ray diffraction, Fourier transform infrared spectroscopy tests, scanning electron microscopy, and transmission electron microscopy. CN‐APP was incorporated into EP and then cured with m‐phenylenediamine. The thermal conductive value of EP/CN‐APP thermosets achieved 1.09 W·mK^?1, and the samples achieved UL‐94 V‐0 grade during vertical burning tests with the limiting oxygen index of 30.1% when 7 wt% CN‐APP with the mass fraction of APP/g‐C₃N₄ of 9/1 was incorporated. For comparative investigation, equal amount of individual g‐C₃N₄ was introduced into EP thermosets, and the thermal conductivity was only 0.4 W·mK^?1. Compared with pure EP, the addition of CN‐APP enhanced the glass transition temperature of EP/CN‐APP thermosets and promoted the generation of more expanded, coherent, and compact char layer during combustion. Consequently, the heat release and smoke production of EP/CN‐APP thermosets were greatly suppressed and led to the improvement of fire safety of materials. It was an alternative and promising approach for preparing high‐performance polymeric materials especially used in integrated electronic devices.     

Effects of kaolin on the thermal stability and flame retardancy of polypropylene composite

Kaolin clay was introduced into an intumescent flame retardant (IFR) system containing ammonium polyphosphate as an acid source and pentaerythritol as a carbonization agent in order to improve the thermal stability and flame retardancy of polypropylene (PP) composite. The flame retardancy and smoke suppression was evaluated by the limiting oxygen index, vertical burning UL‐94, and cone calorimeter (CONE) tests. The limiting oxygen index value was increased from 30 to 33 at the presence of 2 phr kaolin. The peak heat release rate value decreased from 1002 kW/m² of neat PP to 318 kW/m² of PP/40 phr IFR and then to 222 kW/m² of PP/38 phr IFR/2 phr kaolin. The time of the peak heat release rate was significantly prolonged after the introduction of kaolin. The morphology of char after combustion was characterized by a scanning electron microscope, and it revealed more compact char structure that was obtained at the presence of kaolin. The mechanism of kaolin on improving the retardancy and smoke suppression of PP/IFR composite was proposed on the basis of X‐ray photoelectron spectroscopy analysis. Copyright © 2014 John Wiley & Sons, Ltd.     

Joint‐aggregation intumescent flame‐retardant effect of ammonium polyphosphate and charring agent in polypropylene

In order to explore the structure mode of intumescent flame retardants (IFRs) with higher efficiency, IFR particles with joint‐aggregation structure (@IFR) were obtained through the treatment of ammonium polyphosphate (APP) and a charring agent (PT‐Cluster) in their aqueous solution. Then, the joint‐aggregation IFR effect was researched using its application in polypropylene. In case of 20 wt% IFR loading, the limiting oxygen index (LOI) value of @IFR/PP was 1.1% higher than that of 15APP/5PT‐Cluster/PP mixture, and a 1.6 mm‐thick @IFR/PP composite passed the UL 94 V‐2 rating test, while 15APP/5PT‐Cluster/PP demonstrated no flame‐retardant rating in UL 94 vertical burning tests. In a cone calorimeter test, @IFR also had a better inhibition effect on heat release. The average heat release rate (av‐HRR) value during 0 to 120 seconds of @IFR/PP was only 41 kW m^?2, which was 33.9% lower than that of the 15APP/5PT‐Cluster/PP. Furthermore, the peak heat release rate (pk‐HRR) of @IFR/PP was 20.5% lower than that of 15APP/5PT‐Cluster/PP, and the time to pk‐HRR of @IFR/PP was 710 seconds, while that of 15APP/5PT‐Cluster/PP was 580 seconds. The better inhibition effect on HRR and the delay of time to pk‐HRR were caused by the joint‐aggregated structure of @IFR, which can rapidly react to form stable and efficient char layers. This kind of join‐aggregation IFR effect has great significance in suppressing the spread of fire in reality. In addition, @IFR also increased the mechanical properties of PP composites slightly compared with the APP/PT‐Cluster mixture.     

Preparation and properties of an efficient smoke suppressant and flame‐retardant agent for thermoplastic polyurethane

APP@ETA, as a new type of flame retardant, was prepared by chemically modifying ammonium polyphosphate (APP) with ethanolamine (ETA) and applied to thermoplastic polyurethane (TPU) in this study. Then, the smoke suppression properties and flame‐retardant effects of APP@ETA in TPU composites were evaluated using smoke density test, cone calorimeter test, etc. And, the thermal degradation properties of flame‐retardant TPU composites were investigated by thermogravimetric analysis/infrared spectrometry. The smoke density test results indicated that APP@ETA could obviously improve the luminous flux of TPU composites in the test with or without flame. The cone calorimeter test results showed that total smoke release, smoke production rate and smoke factor of the composites with APP@ETA were significantly decreased than those of the composites with APP. For example, when the loading of APP@ETA or APP was 12.5 wt%, the total smoke release of the sample with APP@ETA decreased to 3.5 m²/m² from 6.0 m²/m², which was much lower than that of the sample with APP, reduced by 41.7%. The thermogravimetric analysis results demonstrated that APP@ETA could decrease the initial decomposition temperature and improve the thermal stability at high temperature for TPU composites. Copyright © 2017 John Wiley & Sons, Ltd.     

Flame retardancy and smoke suppression of molybdenum trioxide doped magnesium hydrate in flexible polyvinyl chloride

In this paper, an effective flame retardant consisting of hierarchical magnesium hydrate (MH) nanosheets doped with molybdenum trioxide nanoparticles (MO@MH) was successfully synthesized via a hydrothermal process. Then, MO@MH, MH, and MH/MO were respectively incorporated into flexible polyvinyl chloride (fPVC) to prepare a series of composites via melt blending. The results of limiting oxygen index (LOI), UL‐94, and cone calorimetry test showed that MO@MH exhibited better flame retardancy and smoke suppression than MH and MH/MO due to the synergistic effect of MO and MH, and the hierarchical structure of MO@MH. With the addition of 20 phr MO@MH, LOI value of fPVC was increased from 23.9% to 33.8% , and UL‐94 reached V0 rating. The peak heat release rate, total heat release, peak smoke production rate, and total smoke production were decreased to 143.0 kW/m², 44.9 MJ/m², 0.0093 m²/s and 29.4 m², respectively. The thermogravimetric analysis results suggested that MO@MH greatly promoted the dehydrochlorination of fPVC at lower temperature, so that more compact and continuous char residues were formed. The Fourier transform infrared spectroscopy results indicated that MO@MH can prevent chain scission and oxidation of fPVC carbonaceous backbone, and as a result less smoke was released.     

Synthesis of CeO2‐loaded titania nanotubes and its effect on the flame retardant property of epoxy resin

A series of CeO₂‐loaded titania nanotubes (CeO₂‐TNTs) hybrid materials with different CeO₂ loadings were synthesized by co‐precipitation method and then incorporated into epoxy resin (EP) to prepare CeO₂‐TNTs flame‐retardant epoxy nanocomposites. Structure and morphology characterization indicated the successful synthesis of CeO₂‐TNTs. The effect of CeO₂‐TNTs with different CeO₂ loading capacity on the flame retardance of EP was compared and analyzed by the thermogravimetric analysis, Cone and Raman. The results showed that CeO₂ loading could increase the carbon residue of nanocomposites, reduce the peak heat release rate (PHRR) and total heat release (THR), and improve the fire safety of EP. The residual carbon content of EP/0.1CeO₂‐TNTs sample at 700°C reached 19.8% with the lowest degradation rate, and the PHRR and THR were reduced to 680 kW/m² and 32.9 MJ/m², respectively. Such a significant improvement in flame‐retardant properties for EP could be attributed to the protective effect of CeO₂‐TNTs.     

A novel graphene hybrid for reducing fire hazard of epoxy resin

Epoxy resin (EP) is more and more important in many fields, but its application is limited due to the inflammability in air of EP. Therefore, reducing the fire hazard of EP is necessary. In this work, a kind of hybrid flame retardant (α‐ZrP‐RGO) consisting of a 2‐dimensional inorganic reduced graphene oxide (RGO) modified with a planar‐like α‐zirconium phosphate (α‐ZrP) particles was prepared successfully via 1‐step hydrothermal method. The effects of α‐ZrP‐RGO on the thermal performance, flame retardancy, and smoke suppression of EP were investigated by preparing EP composites containing both EP and α‐ZrP‐RGO. Thermogravimetric results revealed that α‐ZrP‐RGO could improve the char yield of EP at 700°C obviously. In addition, compared with pure EP, the peak heat release rate and the total heat release of EP composites were decreased significantly, while the limited oxygen index of EP composites was increased. Meanwhile, the smoke production rate of EP composites was reduced obviously with the addition of α‐ZrP‐RGO. The enhanced flame retardancy and smoke suppression of EP composites were mainly attributed to not only the physical barrier effect of both α‐ZrP and RGO but also the catalytic effect of α‐ZrP during the combustion process of EP composites.     

Flame retardancy of carbon nanofibre/intumescent hybrid paper based fibre reinforced polymer composites

A hybrid nanopaper consisting of carbon nanofibre (CNF) and/or clay, polyhedral oligomeric silsesquioxane (POSS), ammonium polyphosphate (APP), has been fabricated through the papermaking process. The as-prepared hybrid nanopaper was then incorporated onto the surface of glass fibre (GF) reinforced polymer matrix composites through injection moulding. The morphologies of hybrid nanopapers with and without the polymer resin were characterized with scanning electron microscopy (SEM). The polymer resin penetrated the entire nanopaper under a high-pressure compressed air system. The thermal decomposition behaviour of hybrid nanopapers infused with resin was studied with real-time thermogravimetric analysis/Fourier transform infrared spectrometry (TGA/FTIR). The test results indicate that the addition of clay in the hybrid paper increased the char residues of the nanocomposites. The fire retardant performance of composite laminates incorporating hybrid nanopaper was evaluated by cone calorimeter testing using a radiant heat flux of 50 kW/m². The cone test results indicated that the peak heat release rate (PHRR) decreased dramatically in the case of laminate composites incorporating CNF/clay/APP hybrid paper. However, the extent of reduction of PHRR of the composite laminates incorporated with CNF/POSS/APP hybrid paper was lower. The formation of compact char materials was observed on the surface of the residues and analyzed by SEM and X-ray photoelectron spectroscopy (XPS). The flame retardant mechanisms of hybrid nanopapers in composite laminates are discussed.     

Carbon Fibers Decorated by Polyelectrolyte Complexes Toward Their Epoxy Resin Composites with High Fire Safety

The achievement of both robust fire-safety and mechanical properties is of vital requirement for carbon fiber(CF) composites.To this end, a facile interfacial strategy for fabricating flame-retardant carbon fibers decorated by bio-based polyelectrolyte complexes(PEC) consisting of chitosan(CH) and ammonium polyphosphate(APP) was developed, and its corresponding fire-retarded epoxy resin composites(EP/(PEC@CF)) without any other additional flame retardants were prepared. The decorated CFs were characterized by SEMEDX, XPS and XRD, indicating that the flame-retardant PEC coating was successfully constructed on the surface of CF. Thanks to the nitrogen-and phosphorous-containing PEC, the resulting composites exhibited excellent flame retardancy as the limiting oxygen index(LOI) increased from 31.0% of EP/CF to 40.5% and UL-94 V-0 rating was achieved with only 8.1 wt% PEC. EP/(PEC8.1@CF) also performed well in cone calorimetry with the decrease of peak-heat release rate(PHRR) and smoke production rate(SPR) by 50.0% and30.4%, respectively, and the value of fire growth rate(FIGRA) was also reduced to 3.41 kW·m~(-2)·s~(-1) from 4.84 kW·m~(-2)·s~(-1), suggesting a considerably enhanced fire safety. Furthermore, SEM images of the burning residues revealed that the PEC coating exhibited the dominant flame-retardant activity in condensed phase via the formation of compact phosphorus-rich char. In addition, the impact strength of the composite was improved, together with no obvious deterioration of flexural properties and glass transition temperature. Taking advantage of the features, the PEC-decorated carbon fibers and the relevant composites fabricated by the cost-effective and facile strategy would bring more chances for widespread applications.     

Simultaneously improving the thermal conductive and flame retardant performance for epoxy resins thermosets by constructing core‐shell‐brush structure and distributing of MWCNTs in brush intervals

Fire safety and thermal dissipation performance of epoxy resins thermosets were critical for its application in key fields such as electronic devices. The simultaneous improvement of flame retardant and thermal conductivity properties were still a challenge. Herein, ammonium polyphosphate (APP) was firstly encapsulated with 5‐wt% epoxy resins based on APP and then surface grafted with polyurethane polymer chain, and the resulting APP with core‐shell‐brush structure was constructed. Finally, the multiwalled carbon nanotube (MWCNT) was assembled in the intervals of polymer brush on APP surface, and the prepared filler was defined as MF‐APP. Its chemical structure and morphologies were characterized and confirmed. The wettability of MF‐APP was evaluated by water contact angles tests (WCA) and MF‐APP exhibited hydrophobic property with the WCA of 138°. When 9‐wt% MF‐APP was incorporated into EP thermosets, the thermal conductive value of EP/MF‐APP achieved 1.02 Wm^?1 K^?1, and the MWCNTs concentration was only 1.8 wt% in thermosets. Compared with the previous work, the prepared EP/MF‐APP thermosets exhibited outstanding thermal conductive efficiency because of the homogeneously distribution of MWCNTs. Moreover, the samples fulfilled UL‐94 V‐0 grade during vertical burning tests with the limiting oxygen index of 30.8%. As a result, the thermal conductivity and flame retardancy of EP thermosets were simultaneously enhanced with a relatively low addition amount of MF‐APP, which would bring more chance for wider application of EP thermosets in key fields.     

Fabrication of ZIF‐8@Polyphosphazene core‐shell structure and its efficient synergism with ammonium polyphosphate in flame‐retarding epoxy resin

A novel zeolitic imidazolate framework (ZIF‐8) nanoparticles@polyphosphazene (PZN) core‐shell architecture was synthesized, and then, ZIF‐8@PZN and ammonium polyphosphate (APP) were applied for increasing the flame retardancy and mechanical property of epoxy resin (EP) through a cooperative effect. Herein, ZIF‐8 was used as the core; the shell of PZN was coated to ZIF‐8 nanoparticles via a polycondensation method. The well‐designed ZIF‐8@PZN displayed superior fire retardancy and smoke suppression effect. The synthesized ZIF‐8@PZN observably raised the flame retardancy of EP composites, which could be demonstrated by thermogravimetric analysis (TGA) and a cone calorimeter test (CCT). The chemical structure of ZIF‐8@PZN was characterized by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Compared with pure epoxy, with the incorporation of 3 wt% ZIF‐8@PZN and 18 wt% APP into the EP, along with 80.8%, 72.6%, and 64.7% decreased in the peak heat release rate (pHRR), the peak smoke production rate (pSPR), and the peak CO production rate (pCOPR), respectively. These suggested that ZIF‐8@PZN and APP generated an intumescent char layer, and ZIF‐8@PZN can strengthen the char layer, resulting in the enhancement in the flame resistance of EP.     

Fire‐safe agent integrated with oyster shell and melamine polyphosphate for thermoplastic polyurethane

At present, thermoplastic polyurethane (TPU) is widely used, but there are still many defects in fire safety, such as burning with heavy smoke and dripping. In this article, OS@MP was synthesized by modifying oyster shell (OS) powder with melamine polyphosphate (MP) and then served as fire‐safe agent for TPU. The fire performance of TPU composites were investigated using microscale combustion colorimeter (MCC), cone calorimeter test (CCT), smoke density test (SDT), and thermogravimetric analysis/Fourier transform infrared (TG‐FTIR) spectrum analysis. The MCC and CCT results revealed that OS@MP could reduce the fire hazards of TPU composites. The peak heat release rate (pHRR) of the sample with 10.0 wt% OS@MP decreased to 170.86 kW/m² from 1772.37 kW/m² for pure TPU. And, the SDT results showed that OS@MP could significantly reduce the smoke production of TPU composites. The TG‐FTIR also confirmed that the noncombustible gases (including CO₂, ammonia, and water vapor) produced by OS@MP have played a reinforcing role in TPU composites as well as a char formed on the surface of composites, which could act as a barrier to prevent the heat and air, reinforce the fire safety of TPU.     

Phosphorus‐containing Salen‐metal complexes investigated for enhancing the fire safety of thermoplastic polyurethane (TPU)

Three novel phosphorus‐containing Salen‐based derivatives (Salen‐DPCP‐M: M = Ni, Zn, and Mn), which include both phenyl phosphate structures (DPCP) and Salen‐metal complexes, were prepared for enhancing the fire safety of thermoplastic polyurethane (TPU). Thermogravimetric analysis (TGA) showed that Salen‐DPCP‐M altered the thermal degradation pathways of TPU probably due to the phosphorus‐containing structure of Salen‐DPCP‐M. The cone calorimeter test showed that the addition of 3 wt% of Salen‐DPCP‐Ni, Salen‐DPCP‐Zn, and Salen‐DPCP‐Mn lowered the peak of heat release rate (PHRR) from 1495 kW/m² for neat TPU to 690, 875, and 813 kW/m², respectively, for the TPU composites, which demonstrated that Salen‐DPCP‐M improved the fire safety of TPU. In addition, the release of toxic CO gas from the Salen‐DPCP‐Ni/TPU and Salen‐DPCP‐Zn/TPU composites was reduced by 78.2% and 80.0%, respectively. The results of TGA/infrared spectrometry (TG‐FTIR) showed that the incorporation of Salen‐DPCP‐Ni promoted the release CO₂, while reducing the formation of harmful gases. Laser Raman spectroscopy (LRS) and scanning electron microscopy (SEM) showed that Salen‐DPCP‐Ni/TPU and Salen‐DPCP‐Zn/TPU composites formed a dense and stable char layer. Herein, the mechanism of these flame retardants containing novel phosphorus‐containing Salen‐metal complexes is also proposed.     

Thermal and Mechanical Properties of Zeolite Filled Ethylene Vinyl Acetate Composites

Ethylene vinyl acetate (EVA) composites filled with zeolite (25 vol.%) were prepared using an internal mixer followed by compression molding machine. In order to enhance the thermal properties and fire retardancy of the composites, an intumescent flame retardant consisting of ammonium polyphosphate (APP)/pentaerythritol (PER) was incorporated into the composites. Two kinds of flame retardants were used which are untreated APP (APP1) and silane treated APP (APP2), where their effectiveness was evaluated by means of differential scanning calorimetry (DSC) and also thermogravimetric analysis (TGA). The results showed that both types of flame retardants have the ability to enhance the thermal stability of EVA/zeolite composites by producing charred layer which protects the underlying composites from the action of flame. Moreover, the incorporation of APP1 and APP2 has a significant effect on the composites degree of crystallinity. Meanwhile the results of tensile testing showed that the composites with APP2/PER exhibit better tensile properties compared to that with APP1/PER. This is expected since the application of silane-treated APP (APP2) could improve the dispersion of APP particles within EVA matrix.     

Aluminum phosphate modified brucite and its flame retardant and smoke suppression performance on ethylene‐vinyl acetate resin

A novel halogen‐free flame retardant (FR) consisting of brucite, aluminum phosphate (AlP), and silane coupling agent (B/AlP/A) was prepared via co‐precipitation assembly technique. The morphology, chemical compositions, size distribution, and thermal stability of B/AlP/A were investigated. When used in ethylene‐vinyl acetate (EVA) resin, the B/AlP/A could significantly enhance the flame retardant and smoke suppression performance of the EVA composites, which is mainly attributed to the AIP. With 50 wt% FR loading, the peak heat release rate (PHRR) of EVA‐B/AlP/A (299.2 kW · m^?2) is much lower than that of EVA‐B/A (387.4 kW · m^?2). Moreover, B/AlP/A shows an excellent smoke suppression performance. For example, the smoke production rate is 0.017 m² · g^?1 that has been decreased by 72.1%, compared with B/A. The improvement arises from the amorphous AlP layer on brucite, which helps to create a firm and porous protective char layers on the burning EVA composites. Meanwhile, better mechanical property could be simultaneously obtained with the large FR amount. The fluffy surface of B/AlP/A has good compatibility with EVA and tangle more polymer chains, enhancing the mechanical properties. In a word, this simple and convenient method could pave the way for developing a more efficient and cost‐effective brucite‐based FR.     

Microencapsulated ammonium polyphosphate with epoxy resin shell: preparation,characterization, and application in EP system

Microencapsulated ammonium polyphosphate with an epoxy resin (EP) shell (MCAPP) was prepared by in situ method, and was characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), and thermgravimetric analysis (TGA). Compared to ammonium polyphosphate (APP), MCAPP has smaller particle sizes and lower water solubility. The effect of MCAPP on the fire performance of EP was studied by using limiting oxygen index (LOI) and UL‐94 tests. When the same loading levels of APP or MCAPP were added into EP, the LOI and UL‐94 tests show similar results. Tensile, bending, and impact strengths of the EP/APP and EP/MCAPP composites were also evaluated, and the results indicate that MCAPP has much less negative influence on the mechanical properties than APP. Copyright © 2010 John Wiley & Sons, Ltd.     

Synergistic effects of organo‐sepiolite and zinc borate on the fire retardancy of polypropylene

Polypropylene (PP)/sepiolite/zinc borate (BZn) composites were prepared by melt extrusion after pre‐modification of sepiolite with cetyltrimethylammonium bromide. The synergistic effects of organo‐sepiolite (OSEP) and BZn on the fire retardancy of PP were studied. X‐ray diffraction and transmission electron microscopy were used to characterize the morphology of the composite. Thermogravimetric analysis, cone calorimetric analysis, limiting oxygen index, and the UL‐94 protocol (Demaisheng technology Co. Ltd.,Shenzhen,China) were used to assess the thermal stability and fire retardancy of the composites. The fire retardancy of PP was greatly improved by introducing OSEP and BZn. The reduction in peak heat release rate for PP/BZn composites at 10% BZn loading is 62% compared with pristine PP, but increased to 78% for PP/10%BZn/10%OSEP composite. Other fire retardant parameters were also improved. The fire performance index of PP/10%BZn/10%OSEP composite was 0.045 sm²/kW compared with 0.014 sm²/kW of pristine PP. The average mass loss rate was 12.1 g/sec/m² for the composite with both additives compared with 30.1 g/sec/m² for pristine PP; the smoke production rate decreased by 37% from 0.117 m²/s of pristine PP to 0.074 m²/s of PP/OSEP/BZn. The char residue of composite increased from 0.6% in pristine PP to 12.19% in the composite. The limiting oxygen index increased from 17.1 in pristine PP to 20.8 in the composite: all the samples could obtain a UL‐94 horizontal burn rating. Copyright © 2013 John Wiley & Sons, Ltd.