Flame retardation and thermal degradation of flame‐retarded polypropylene composites containing melamine phosphate and pentaerythritol phosphate

The flame retardation of polypropylene (PP) composites containing melamine phosphate (MP) and pentaerythritol phosphate (PEPA) was characterized by limiting oxygen index (LOI) and UL 94. The morphology of the char obtained from the combustion of the composites was studied by scanning electron microscopy (SEM). The thermal degradation of the composites was investigated using thermogravimetric (TG) analysis and real‐time Fourier transform infrared (RTFTIR) spectroscopy. It has been found that the PP composites containing only MP do not show good flame retardancy even at 40% additive level. Compared with the PP/MP binary composites, all the LOI values of the PP/MP/PEPA ternary composites at the same additive loading increase, and UL 94 ratings of the ternary composites at suitable MP/PEPA ratios are raised to V‐0 from no rating (PP/MP). The TG and RTFTIR studies indicate that the interaction occurs among MP, PEPA and PP. Copyright © 2008 John Wiley & Sons, Ltd.     

Preparation and characterization of double shell microencapsulated ammonium polyphosphate and its flame retardance in polypropylene

Microencapsulated ammonium polyphosphate (MUFAPP) with a double shell is prepared by in situ polymerization, and is characterized by FTIR, XPS and SEM, etc. The microencapsulation of APP can increase its flame retardance and water resistance in PP. The flame retardant action of MUFAPP and APP in PP are studied using LOI and UL 94 test, and their thermal stability is evaluated by TG. The LOI value of the PP/MUFAPP composite at the same loading is higher than that of PP/APP composite. The LOI values of the PP/MUFAPP/ dipentaerythritol are higher than that of the PP/MUFAPP, and UL 94 ratings of most ternary composites are raised to V-0 at 30 wt.% loading. The results of the cone calorimeter also indicate that MUFAPP is an effective flame retardant in PP. The thermal degradation behaviors of APP and MUFAPP are studied using TG and dynamic FTIR.     

An easy‐to‐obtain silicone‐containing flame retardant and its effects on the combustion of polycarbonate

A novel silicone‐containing flame retardant (HSOBA) synthesized from hydrogen‐containing silicone oil and Bisphenol A via a simple approach has been incorporated into polycarbonate (PC) matrix to study its effects on the flame retardancy. The flame retardancy of PC/HSOBA composites is investigated by limiting oxygen index (LOI), vertical burning tests (UL‐94), and cone calorimeter measurement. The LOI value of the composites is 31.7 and the UL‐94 rating reaches V‐0, when the content of HSOBA is 3 wt %. Cone calorimeter data confirm that the HSOBA acts as an effective additive functioning both as flame retardants and as smoke suppressant. Evolution of the thermal behaviors of the composites tested by TGA, the morphological structures, and the constituent of char residue after LOI tests characterized by scanning electronic microscopy‐energy‐dispersive X‐ray analysis were used to explain the possible flame‐retardant mode. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Flame Retardant Synergism of Hydroxy Silicone Oil and Al(OH)3 in EVA Composites

A synergistic effect on flame retardancy was found when hydroxy silicone oil (HSO) was incorporated into ethylene vinyl acetate/aluminum hydroxide (EVA/ATH) composite. The fire performance of EVA and EVA composites was studied by using limiting oxygen index (LOI), UL 94, and cone calorimeter test (CCT). Compared with the EVA/ATH binary composite, the LOI values of the EVA/ATH/HSO ternary composites at the same additive loading are all decreased. The CCT data indicated that the addition of HSO in EVA/ATH system not only reduces the heat release rate, but also prolonged the ignition time of the composite. Thermogravimetric analysis revealed that ATH accelerated the loss of acetic acid, but hydroxy silicone oil assisted to reduce ATH's accelerating effect.     

Effect of charring agent THEIC on flame retardant properties of polypropylene

Tris(2‐hydroxyethyl) isocyanurate (THEIC) was used as charring agent and combined with ammonium polyphosphate (APP) to form an intumescent flame retardant (IFR) for polypropylene (PP). The flame retardancy and combustion performance of PP/IFR composite was tested by limiting oxygen index (LOI), UL‐94 vertical burning test and cone calorimeter. The results showed that PP/IFR composite had highest LOI of 34.8 and obtained V‐0 rating when 30 wt % IFR was loaded and mass ratio APP/THEIC was 2 : 1. The peak heat release (PHRR) and total heat release (THR) values of PP composite containing FRs were remarkably reduced compared with that of pure PP. However, water resistant test demonstrated the PP/IFR composite had poor flame retardant durability, both the LOI value and UL‐94 V‐rating decreased when PP/IFR composite was soaked in water at 70°C after 36 h. The degradation process and the char morphology of IFR and PP/IFR composite were investigated by TGA and SEM images. The possible reaction path between APP and THEIC in the swollen process was proposed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41214.     

Synergistic flame retardant effects of ammonium polyphosphate in ethylene‐vinyl acetate/layered double hydroxides composites

Mg–Al–Fe ternary layered double hydroxides (LDH) were synthesized based on bayer red mud by calcination‐rehydration method, and characterized using X‐ray diffraction and thermogravimetric analysis (TGA). The synergistic flame retardant effects of ammonium polyphosphate (APP) with LDH in ethylene‐vinyl acetate (EVA) composites were studied using limiting oxygen index (LOI), UL 94 test, cone calorimeter test (CCT), and smoke density test (SDT). The thermal degradation behavior of EVA/LDH/APP composites was examined by thermal gravimetric analysis‐fourier transform infrared spectrometry (TG‐FTIR). The results showed that LOI values decreased by incorporation of APP together with LDH; and, a suitable amount of APP in EVA/LDH composites can apparently improve UL 94 rating. The CCT results indicated that heat release rate (HRR) of the EVA/LDH/APP composites with APP decreased in comparison with that of the EVA/LDH composites. The SDT results showed that APP was helpful to suppress smoke. The TG‐FTIR data showed that the composites with APP had a higher thermal stability than the EVA/LDH composites at high temperature. POLYM. ENG. SCI., 54:766–776, 2014. © 2013 Society of Plastics Engineers     

Study on effect of polydimethylsiloxane in intumescent flame retardant polypropylene

The effect of polydimethylsiloxane (PDMS) in intumescent flame retarded polypropylene (PP) containing melamine phosphate (MP) was studied using limiting oxygen index (LOI), UL-94 test, thermogravimetric analysis (TG), real time Fourier transform infrared (FTIR) and pyrolysis/gas chromatogram/mass spectrometry (Py–GC/MS). It was found that the addition of PDMS into the PP/MP composites leads to a decrease in the LOI values of the PP/MP/PDMS composites, and the values increase gradually with the increase of the PDMS content. The UL-94 test results indicate that the PP/MP/PDMS composite with 30% PDMS reaches the V-0 rating compared with no rating of the PP/MP composite at the same MP loading. The water resistance of the PP/MP/PDMS composites was investigated, and the improved water leaching of MP was observed. The TG and RTFTIR results illustrate the thermal stability of the PP/MP composites containing PDMS is improved. Moreover, the pyrolysis of the PP/MP/PDMS composites was studied by the Py–GC/MS method.     

磷系阻燃剂FR/APP协效阻燃PP

采用氧指数测定仪、热重分析仪和锥形量热仪研究了磷系阻燃剂1,3,5-三(5,5-二甲基-1,3-二氧杂环己内磷酸基)苯(FR)和聚磷酸铵(APP)复配体系对聚丙烯(PP)材料阻燃性能的影响.结果表明,FR/APP提高了PP的极限氧指数(LOI)、热稳定性和残炭率,降低了热释放速率.当w(FR)为15%和w(APP)为10%复配阻燃PP时,复合材料的LOI为29.6%.阻燃级别达到UL 94 V-0级.     

Synergistic effect between a triazine‐based macromolecule and melamine pyrophosphate in flame retardant polypropylene

A novel charring agent, namely triazine‐based macromolecule (TBM), was synthesized via solution polycondensation of cyanuric chloride, ethanolamine, and diethylenetriamine. The prepared charring agent possessed little water solubility and superior char‐forming ability, and it showed good synergistic effects with melamine pyrophosphate (MPP) in flame retardant polypropylene (PP). When the content of MPP was 16.7 wt% and TBM was 8.3 wt%, the limiting oxygen index (LOI) of the PP/MPP/TBM composite could reach 31.0%, and a UL‐94 V‐0 rating was achieved based on the vertical burning test. Furthermore, the composite exhibited an outstanding water resistance that it could still obtain a V‐0 rating after soaking in hot water for 168 h. The cone calorimetry test (CCT) results demonstrated that the peak heat release rate (PHRR), the total heat release (THR) and mass lose rate (MLR) of the composite were decreased significantly in comparison with those of pure PP. The thermogravimetric analysis (TGA), thermogravimetry‐Fourier transform infrared spectrometry (TG‐FTIR), and scanning electron microscopy‐energy dispersive spectra (SEM‐EDS) results revealed that the efficient flame retardancy of MPP/TBM was mainly attributed to the formation of a compact and thermostable intumescent char on underlying materials during a fire. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Role of caged bicyclic pentaerythritol phosphate alcohol in flame retardancy of PA6 and mechanism study

A series of PA6/PEPA composites were prepared by mixing caged bicyclic pentaerythritol phosphate alcohol (PEPA) and polyamide 6 (PA6) at different feed ratios by the melt‐blending method in a twin‐screw extruder. The influence of PEPA on the flame‐retardant properties of PA6 was investigated using the limiting oxygen index (LOI), the Underwriters Laboratories UL‐94 test, and the cone calorimeter method. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, X‐ray photoelectron spectroscopy, thermogravimetry (TG), and TG‐FTIR were conducted to study the influence of PEPA on the thermal decomposition and the mechanism of performance of PA6 from products of condensed and gaseous phases. The results show that the LOI value and the content of residual char of PA6/PEPA composites increased with increasing PEPA content, and an LOI value of 38% could be reached when the feed ratio of PEPA was 30 wt %. The average heat release rate and total heat release drastically decreased with increasing content of PEPA, and the amount of carbon residue increased by 52.9% over neat PA6 after TG tests. The inorganic acid produced by PEPA during combustion can be used as an acid source to promote the dehydration of PA6 and the processes of esterification crosslinking, arylation, and carbonization. Moreover, there was less CO₂ released than by PA6, and more carbon‐containing compound remained in the composites so that a stable carbon layer structure was formed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46236.     

Synthesis and characterization of a novel charring agent and its application in intumescent flame retardant polypropylene system

A novel halogen‐free charring agent bi(4‐methoxy‐1‐phospha‐2, 6, 7‐trioxabicyclo [2.2.2]‐octane‐1‐sulfide) phenylphosphate (BSPPO) was synthesized from phenylphosphonic dichloride (PPDC), and 4‐hydroxymethyl‐1‐phospha‐2, 6, 7‐trioxabicyclo[2.2.2]‐octane‐1‐sulfide (SPEPA) which was synthesized from pentaerythritol and thiophosphoryl chloride in this article. The structure of BSPPO and SPEPA was characterized by Fourier transform infrared (FTIR), ¹H‐NMR, ¹³C‐NMR, and ³¹P‐NMR. Combined with ammonium polyphosphate (APP) and melamine pyrophosphate (MPP), the flame retardance and dripping resistance of BSPPO added in polypropylene (PP) were investigated. The fire performance of the flame retardant PP system was investigated by limiting oxygen index (LOI), vertical burning test (UL‐94), and cone calorimeter. The thermal stabilities of the composites were studied by thermogravimetric analysis (TGA). The flame retardance mechanism was investigated by FTIR and scanning electronic micrograph (SEM). The mechanical properties and water solubility were also investigated. The residue of BSPPO is 40.6% at 600°C, which indicates BSPPO has excellent charring ability. The char residue of the polypropylene intumescent flame retardant (PP‐IFR) system is 22% at 600°C, which suggests that the flame retardation synergy of APP, BSPPO, and MPP is good. With the optimum formulation, the LOI of the IFR‐PP system is 32.0, and the UL‐94 is V‐0 rating. The heat release rate (HRR), total heat release (THR), smoke production rate (SPR), total smoke production (TSP), and mass loss rate (MLR) of IFR‐PP with the optimum formulation decrease significantly comparing to pure PP from cone calorimeter analysis. The FTIR and SEM results indicate that the char properties and the char yield have direct effect on the flame retardance and antidripping behaviors. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synergistic effects of hydroxy silicone oil on intumescent flame retardant polypropylene system

The effects of hydroxy silicone oil as a synergistic agent on the flame retardancy of intumescent flame retardant polypropylene composites (IFR-PP) were studied, and the IFR system mainly consisted of the ammonium polyphosphate (APP), melamine (MEL) and pentaerythritol (PER). The UL 94 rating, thermogravimetric analysis (TGA), cone calorimeter (CONE) and digital photograph were used to evaluate the synergistic effects of hydroxy silicone oil (HSO). It has been found that the PP composite containing only APP, MEL and PER does not show good flame retardancy at 30% additive level. The cone calorimeter results show that the heat release rate, mass loss rate, mass, total heat release, carbon monoxide and carbon dioxide of PP/APP/MEL/PER/HSO composites decrease in comparison with the PP/APP/MEL/PER composite. The digital photographs demonstrated that HSO could promote to form the homogenous and compact intumescent char layer. Thus, a suitable amount of HSO plays a synergistic effect in the flame retardancy.     

Flammability and thermal degradation of epoxy acrylate modified with phosphorus‐containing compounds

A series of UV‐curable flame‐retardant resins was obtained by blending phosphate acrylate (BTP) in different ratios with epoxy acrylate resin (EA). The flammability was characterized by limiting oxygen index (LOI), UL 94 flammability rating and cone calorimeter, and the thermal degradation of the flame‐retardant resins was studied using thermo gravimetric analysis (TGA), and real‐time Fourier transform infrared (RTFTIR). The results indicated that the flame‐retardant efficiency increases with the addition of BTP. The heat release rate with the addition of BTP decreases greatly. The TGA data showed that EA/BTP blends have lower initial decomposition temperatures and higher char residues than pure EA, whereas BTP has the lowest initial decomposition temperature and the highest char residue. The RTFTIR study indicates that the EA/BTP blends have lower thermal oxidative stability than the pure EA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of a magnesium/aluminum/iron layered double hydroxide and its flammability characteristics in halogen‐free,flame‐retardant ethylene/vinyl acetate copolymer composites

Mg–Al–Fe ternary hydrotalcites were synthesized by a coprecipitation method and characterized with powder X‐ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The flame‐retardant effects of Mg/Al–CO₃ layered double hydroxides (LDHs) and Mg/Al/Fe–CO₃ LDHs in an ethylene/vinyl acetate copolymer (EVA) were studied with the limited oxygen index (LOI), the UL‐94 test, and the cone calorimeter test (CCT), and the thermal degradation behavior of the composites was examined by thermogravimetric analysis. The results showed that the LOI values of the EVA/(Mg/Al/Fe–CO₃ LDH) composites were basically higher than those of the EVA/(Mg/Al–CO₃ LDH) composites at the same additive level. In the UL‐94 test, there was no rating for the EVA/(Mg/Al–CO₃ LDH) composite at the 50% additive level, and a dripping phenomenon occurred. However, the EVA/(Mg/Al/Fe–CO₃ LDH) composites at the same loading level of LDHs containing a suitable amount of Fe³⁺ ion reached the V‐0 rating, the dripping phenomenon disappearing. The CCTs indicated that the heat release rate (HRR) of the EVA composites with Mg/Al/Fe–CO₃ LDHs containing a suitable amount of Fe³⁺ decreased greatly in comparison with that of the composites with Mg/Al–CO₃ LDHs. The introduction of a given amount of Fe³⁺ ion into Mg/Al–CO₃ LDHs resulted in an increase in the LOI, a decrease in the HRR, and the achievement of the UL‐94 V‐0 rating. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Flame retardancy and water resistance of novel intumescent flame‐retardant oil‐filled styrene–ethylene–butadiene–styrene block copolymer/polypropylene composites

A novel halogen‐free flame‐retardant composite consisting of an intumescent flame retardant (IFR), oil‐filled styrene–ethylene–butadiene–styrene block copolymer (O‐SEBS), and polypropylene (PP) was studied. On the basis of UL‐94 ratings and limiting oxygen index (LOI) data, the IFRs consisted of a charring–foaming agent, ammonium polyphosphate, and SiO₂ showed very effective flame retardancy and good water resistance in the IFR O‐SEBS/PP composite. When the loading of IFR was only 28 wt %, the IFR–O‐SEBS/PP composite could still attain a UL‐94 V‐0 (1.6 mm) rating, and its LOI value remained at 29.8% after a water treatment at 70°C for 168 h. Thermogravimetric analysis data indicated that the IFR effectively enhanced the temperature of the main thermal degradation peak of the IFR–O‐SEBS/PP composites because of the formation of abundant char residue. The flammability parameters of the composites obtained from cone calorimetry testing demonstrated that water treatment almost did not affect the flammability behavior of the composite. The morphological structures of the char residue and fractured surfaces of the composites were not affected by the water treatment. This was attributed to a small quantity of IFR extracted from the composite. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39575.     

Study on the flame retardancy of EVM/magnesium hydroxide composites optimized with a flame retardant containing phosphorus and silicon

A novel phosphorus‐silicon‐containing flame retardant, spirocyclic pentaerythritol bisphosphorate disphosphoryl chloride/9, 10‐dihydro‐9‐oxa‐10‐phosphaphanthrene‐10‐oxide/vinyl methyl dimethoxysilane (SPDV), was synthesized successfully and used for optimizing the flame retardancy of ethylene‐vinyl acetate copolymer (EVM) rubber/magnesium hydroxide (MDH) composites. The microstructure of SPDV was characterized and determined by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. Thermogravimetric analysis (TGA) showed that SPDV had good charring effect in air even at high temperature (800°C). The flame retardancy of the optimized EVM/MDH composites by SPDV was investigated by limiting oxygen index (LOI), cone calorimeter, and UL‐94 vertical burning tests. A higher LOI value (29.4%) and better UL‐94 rating (V‐0) can be achieved for the optimized EVM/MDH composite (EVM‐7) than EVM/MDH composite without SPDV (EVM‐3) with the total loading of additives. The HRR decreased and residual mass increased gradually as the loading of SPDV increased for the optimized EVM/MDH composites. There existed distinct synergistic intumescent flame‐retardant effect between SPDV and MDH in EVM matrix. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Microencapsulation of ammonium polyphosphate: Preparation,characterization, and its flame retardance in polypropylene

Microencapsulated ammonium polyphosphate (MCAPP) with a melamine–formaldehyde (MF) resin coating layer was prepared by in situ polymerization. MCAPP was characterized by Fourier transform infrared, X‐ray photoelectron spectroscopy, and so on. The results show that the microencapsulation with MF resin leads to a decrease in the particles' size and water absorption. The flame retardant action and mechanism of MCAPP and ammonium polyphosphate (APP) in polypropylene are studied using limiting oxygen index (LOI) and UL 94 test, and their thermal stability is evaluated by thermogravimetric analysis. The LOI value of the PP/MCAPP composite at 30 wt% loading is 30.5%, whereas the corresponding value of the PP/APP composite is only 20%. Moreover, the LOI values of the PP/MCAPP/PER composites are higher than the ones of the PP/APP/PER composites. In the UL 94 test, the PP/MCAPP/PER composites with suitable ratios of MCAPP to PER can reach the V‐0 rating, and the best rating of the PP/APP/PER composites is V‐1. V‐1. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Fire performance and thermal stability of polypropylene nanocomposites containing organic phosphinate and ammonium polyphosphate additives

In order to develop polymer‐clay nanocomposites with reduced flammability by incorporation of char‐forming conventional nitrogen and phosphorus based flame retardants at low loading levels, the polypropylene‐clay nanocomposites were prepared by melt blending method with Cloisite 15A (15A), organic phosphinate (OP) and ammonium polyphosphate (AP) additives. Thermal analysis shows that addition of 5% 15A along with 15% (w/w) OP in polypropylene (PP)/PPgMA increases the thermal stability of PP/PPgMA/OP/15A composite by 82 °C showing synergistic effect, and the PP/PPgMA/AP/15A sample with same loading becomes thermally stable by 70 °C. Cone calorimeter analysis of the PP/PPgMA/OP/15A and PP/PPgMA/AP/15A composites measures the reduction in peak heat release rate values by 66% and 58%, respectively. Addition of 20% OP to PP/PPgMA enhances the limiting oxygen index (LOI) value and gives V‐2 rating of UL‐94 test. Further, on replacing 5% OP with 5% 15A for PP/PPgMA/OP/15A sample without changing the total 20% loading, the LOI value increases further slightly but give no UL‐94 rating. Also, PP/PPgMA/AP/15A sample with same loading similar to that of PP/PPgMA/OP/15A sample shows an enhancement in LOI value and gives no rating in UL‐94 test. No relation was observed between LOI values and UL‐94 test rating in the present study. Copyright © 2012 John Wiley & Sons, Ltd.     

Synergistic effect of kaolinite/halloysite on the flammability and thermostability of polypropylene

Kaolinite (Kaol) and halloysite nanotubes (HNT) are both aluminosilicate clays with similar chemical formulation and different microshapes. In this article, nanotubular HNT and nanoplate Kaol together were introduced into polypropylene (PP) containing intumescent flame retardant (IFR). The flammability of the PP composites was characterized by limiting oxygen index (LOI), vertical burning (UL‐94), and cone calorimeter tests (CCT). The results showed that for the composite with 75 wt % PP and 25 wt % IFR, its LOI was 31.0% and it obtained a UL‐94 grade of V‐2. For the composite of 75 wt % PP, 23.5 wt % IFR, and 1.5 wt % (Kaol/HNT = 9/1), its LOI increased to 36.9 and it obtained a UL‐94 grade of V‐0; at the same time, its peak heat release rate value in CCT decreased by 82.2% compared to neat PP. The thermostability analysis indicated that the mixture of Kaol/HNT could improve the thermostability and final char yield. The char residues were comprehensively analyzed by scanning electron microscopy and Fourier transform infrared spectroscopy. The results illustrated that the Kaol/HNT combination was beneficial to forming a crosslinked network and promoting formation of a compact char with higher strength. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46507.     

Flame Retardancy and Thermal Performance of Polypropylene Treated With the Intumescent Flame Retardant,Piperazine Spirocyclic Phosphoramidate

Piperazine spirocyclic phosphoramidate (PSP), a novel halogen‐free intumescent flame retardant, was synthesized and used to improve the flame retardancy and dripping resistance of polypropylene (PP) combined with ammonium polyphosphate (APP) and a triazine polymer charring‐foaming agent (CFA). The optimum flame‐retardant formulation was PSP:APP:CFA = 3:6:2 (weight ratio). The flammability and thermal behavior of the (intumescent flame‐retardant)‐PP (IFR‐PP) were investigated via limiting oxygen index (LOI), vertical burning tests (UL‐94), thermogravimetric analysis, and cone calorimetry (CONE). The results indicated that the IFR‐PP had both excellent flame retardancy and anti‐dripping ability. The optimum flame‐retardant formulation gave an LOI value of 39.8 and a UL‐94 V‐0 rating to PP. Moreover, both the heat release rate and the total heat release of the IFR‐PP with the optimum formulation decreased significantly relative to those of pure PP, according to the cone calorimeter analyses. The residues of IFR‐PP obtained after CONE tests were observed by scanning electron microscopy, and it was found that the char yield was directly related to the flame retardancy and anti‐dripping behavior of the treated PP. J. VINYL ADDIT. TECHNOL., 20:10–15, 2014. © 2014 Society of Plastics Engineers