Synergistic effects and flame-retardant mechanism of aluminum diethyl phosphinate in combination with melamine polyphosphate and aluminum oxide in epoxy resin

Journal of Thermal Analysis and Calorimetry - In this work, the melamine polyphosphate (MPP) and aluminum oxide (Al2O3) were used to investigate their synergistic effects with aluminum diethyl...     

Synergistic effects between hollow glass microsphere and ammonium polyphosphate on flame-retardant thermoplastic polyurethane

It is mainly studied that the smoke-suppression properties and synergistic flame-retardant effect of hollow glass microsphere (HM) in flame retardant thermoplastic polyurethane (TPU) composites based on ammonium polyphosphate (APP) as a flame-retardant. Also, the smoke suppression properties and flame-retardant effect were investigated by smoke density test (SDT), cone calorimeter test (CCT), limiting oxygen index, and thermogravimetric analysis, separately. The char residues left after CCT were examined by scanning electron microscopy. The data of SDT shows that HM could effectively decrease smoke production of TPU composites. The results of CCT reveal that the system of APP/HM could reduce heat release rate, smoke production rate, and total smoke release. It is shown that APP/HM is a good system with smoke-suppression and synergistic flame-retardant properties in flame-retardant TPU composites.     

Co-microencapsulate of ammonium polyphosphate and pentaerythritol in intumescent flame-retardant coatings

Co-microencapsulated ammonium polyphosphate (APP) and pentaerythritol (PER) [M (A&P)] is prepared using melamine–formaldehyde resin by in situ polymerization method and characterized using energy dispersive spectrometer and Fourier transform infrared spectra. Thermal stability and fire resistance behavior have been analyzed and compared. The co-microencapsulation of APP and PER leads to a great improvement of its thermal stability investigated by thermogravimetric analysis. The temperature of maximum mass loss rate of M (A&P) is 30 °C higher than that of APP/PER mixture. The flame-retardant effect of M (A&P) in coating composite is evaluated by carbonization volume, flame spread rate, and cone calorimeter. Results show that the flame-retardant properties of M (A&P) in coating composite is much better than that of APP/PER mixture coating composite.     

Effect of aluminum diethylphosphinate and its synergist on flame-retardant effects of epoxy resin

Journal of Thermal Analysis and Calorimetry - In this article, the flame-retardant epoxy resin (EP) material was prepared by aluminum diethylphosphinate (ADP), melamine (MEL) and pentaerythritol...     

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 and mechanism of ZnCl2 on intumescent flame-retardant polypropylene

The synergistic effects of ZnCl₂ on polypropylene (PP)/ammonium polyphosphate/pentaerythritol have been studied. The cone calorimeter test, limiting oxygen index, and UL-94 data show that suitable amount of ZnCl₂ can greatly increase the flame-retardant property of PP/intumescent flame retardant (IFR)/ZnCl₂ blends, however, the corresponding smoke release increased for PP/IFR/ZnCl₂ blends when compared with PP/IFR without ZnCl₂. The dynamic Fourier transfer infrared spectra reveal that the ZnCl₂ accelerated the formation of charred layers with P–O–P and P–O–C complexes which formed from burning of polymer materials. The morphological structures of charred residues observed by scanning electron microscopy give the positive evidence that ZnCl₂ can promote the formation of compact intumescent charred layers and prevent the charred from cracking, which effectively protects the underlying polymer from burning. The thermogravimetric analysis data show that the PP/IFR/ZnCl₂ sample has higher thermal stability than that of PP/IFR and PP/IFR/ZnO samples. However, the corresponding charred residues are much lower than that of PP/IFR/ZnO sample. All the above data indicated that the synergistic mechanism of ZnCl₂ with IFR in PP system can be ascribed to catalyze effects in condense phase and serve as a radical scavenger in vapor phase.     

Double-layered co-microencapsulated ammonium polyphosphate and mesoporous MCM-41 in intumescent flame-retardant natural rubber composites

Double-layered co-microencapsulated ammonium polyphosphate (APP) and mesoporous MCM-41 (M(A&M)) were prepared using melamine–formaldehyde resin and zinc borate by in situ polymerization. The structure of the microcapsules was characterized by particle size analysis, Fourier-transform infrared spectroscopy, and scanning electron microscopy. Double-layered microencapsulation gave APP narrow particle size distribution. The flame-retardant and mechanical effects of M(A&M) in natural rubber (NR) were evaluated using the limiting oxygen index, UL 94 test, thermogravimetric analysis, and tensile test. Results indicated that the NR/M(A&M) composites had much better flame-retardant and mechanical properties than the NR/APP/MCM-41 composites. The limited oxygen index value of the NR/M(A&M) composite reached the maximum, and the UL-94 ratings were increased to V-0 when the ratio of APP to MCM-41 was 39:1 in microcapsule. The occurrence of a synergistic effect between MCM-41 and intumescent flame-retardant in the NR composites was proved. This investigation provided a promising formulation for flame-retardant NR composites.     

Synergistic effects between boron phosphate and microencapsulated ammonium polyphosphate in flame‐retardant thermoplastic polyurethane composites

Microencapsulated ammonium polyphosphate (MAPP) with polyurethane resin has been prepared by in situ polymerization. The combination of MAPP and boron phosphate (BP) on the flammability properties of thermoplastic polyurethane (TPU) was studied by vertical burning (UL‐94) tests, limiting oxygen index tests, cone calorimetry (CONE), and microscale combustion calorimeter (MCC) whereas thermal stability was investigated by thermogravimetric analysis and real‐time Fourier transform infrared. Results showed that a suitable substitution of MAPP by BP could improve flame retardancy of the TPU/MAPP composites and TPU composites with MAPP/BP (15.5/2 wt%) achieving UL‐94 V‐0 rating. The CONE and MCC data showed synergistic effects between BP and MAPP in the composites. Copyright © 2011 John Wiley & Sons, Ltd.     

The synergistic effects of a novel intumescent flame-retardant poly-(4-nitrophenoxy)-phosphazene and ammonium polyphosphate on ABS systems

Journal of Thermal Analysis and Calorimetry - Novel intumescent flame retardancy acrylonitrile–butadiene–styrene (ABS) composites were prepared by adding...     

Metal compound-enhanced flame retardancy of intumescent epoxy resins containing ammonium polyphosphate

A series of intumescent flame-retardant epoxy resins (IFR-EPs) were prepared only by adding a 5 wt% total loading of ammonium polyphosphate (APP) and metal compounds. All the samples could achieve V-0 rating and did not generate dripping during UL-94 testing. The limiting oxygen index (LOI) values of the samples with 4.83 wt% APP and 0.17 wt% CoSA increase from 27.1 to 29.4, compared with epoxy resin containing 5 wt% APP. The samples also showed excellent water resistance of flame retardancy in 30 °C and 70 °C water for 168 h. The LOI results show that the composition of metal compounds (metal ions and ligands/anions) and the mass ratios of APP to metal compounds affect the flame retardancy of the samples. TG results indicate that the catalytic effect of CoSA on the decomposition of both APP and the epoxy resins containing APP is better than that of CuSAO. The fire behavior of epoxy resin and epoxy resins containing APP with/without CoSA were investigated by cone calorimeter. Cone calorimeter parameters of the samples such as HRR, THR, TSP and COP indicate that the addition of APP and CoSA improves the fire safety of epoxy resin significantly, and CoSA shows an obvious catalytic effect.     

A flame-retardant epoxy resin based on a reactive phosphorus-containing monomer of DODPP and its thermal and flame-retardant properties

A flame-retardant epoxy resin (EP) was synthesized based on a novel reactive phosphorus-containing monomer, 4-[(5,5-dimethyl-2-oxide-1,3,2-dioxaphosphorinan-4-yl)oxy]-phenol (DODPP), and its structures were characterized by FTIR, ¹H NMR and ³¹P NMR spectra. The DODPP-EP₃/LWPA (low molecular weight polyamide), which contains 2.5% phosphorus, can reach UL-94 V-0 rating and a limiting oxygen index (LOI) value of 30.2%. The thermal properties and burning behaviours of cured epoxy resins were investigated by differential scanning calorimeter (DSC), thermogravimetry (TG), LOI, UL-94 tests and cone calorimetry. The morphologies of residues of cured epoxy resins were investigated by scanning electron microscopy (SEM). DSC shows that the glass-transition temperatures of cured epoxy resins decrease with increasing phosphorus content. TGA shows that the onset decomposition temperatures and the maximum-rate decomposition temperatures decrease, while char yields increase, with the increase of phosphorus content. The data from the cone calorimeter tests give the evidence that heat release rate (HRR), peak heat release rate (PHRR), average heat release rate (Av-HRR), average mass loss rate (Av-MLR) and the fire growth rate index (FIGRA) decrease significantly for DODPP-EP₃/LWPA. SEM shows that the DODPP-EP₃/LWPA forms lacunaris and compact charred layers which inhibit the transmission of heat during combustion.     

Flame retardant mechanism of an efficient flame-retardant polymeric synergist with ammonium polyphosphate for polypropylene

An efficient flame retardant polymeric synergist poly[N⁴-bis(ethylenediamino)-phenyl phosphonic-N², N⁶-bis(ethylenediamino)-1,3,5-triazine-N-phenyl phosphonate] (PTPA) was designed and synthesized from cyanuric chloride, ethylenediamine and phenylphosphonic dichloride. It was characterized by Fourier Transform Infrared (FTIR), ¹H NMR and ³¹P NMR, Elemental Analysis (EA) and Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). Combined with ammonium polyphosphate (APP), a new intumescent flame retardant (IFR) was obtained. The flammability behaviors of polypropylene (PP)/IFR system were investigated by limiting oxygen index (LOI), vertical burning test (UL-94) and cone calorimetry. With 25 wt% of IFR (APP:PTPA = 2:1), the PP/IFR system could achieve a LOI value of 34.0% and UL-94 V-0 rating, and the heat release rate (HRR), peak heat release rate (PHRR), total heat release (THR) and smoke production rate (SPR) were considerably reduced, especially HRR and SPR were decreased by 85% and 79%, respectively. The results indicate that there is an excellent synergism between APP and PTPA, which endows PP with both good flame retardancy and good smoke suppression. Furthermore, the thermal degradation mechanism of IFR and the flame-retardant mechanism of PP/IFR system were investigated by thermogravimetric analysis (TGA), FT-IR, TG-FTIR and scanning electron microscope (SEM). The study on the flame-retardant mechanism of IFR indicated that a structure containing –CN was formed due to the reaction between APP and PTPA.     

Synergistic effect between expandable graphite and ammonium polyphosphate on flame retarded polylactide

Synergistic effect was observed between expandable graphite (EG) and ammonium polyphosphate (APP) on flame retarded polylactide (PLA) in this paper using limiting oxygen index (LOI), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM) and X-ray spectroscopy (XPS) and cone calorimeter tests etc. In the experiments, PLA composites with 15 wt% of APP/EG(1:3) combinations showed a LOI value of 36.5 and V-0 rating in UL-94 tests, greatly improved flame retardant properties from composites with APP or EG alone. Results from TGA and cone calorimeter demonstrated that APP/EG combination could retard the degradation of polymeric materials above the temperature of 520 °C by promoting the formation of a compact char layer. This char layer protects the matrix effectively from heat penetrating inside and prevents its further degradation, resulting in lower weight loss rate and better flame retarded performance.     

Synergistic effects of pentaerythritol phosphate nickel salt (PPNS) with ammonium polyphosphate in flame retardant of polyethylene

Journal of Thermal Analysis and Calorimetry - Phosphorus oxychloride (POCl3), which is both hazardous and expensive, is currently employed to produce carbon agents for use in intumescent flame...     

Synthesis and thermal properties of silicon-containing epoxy resin used for UV-curable flame-retardant coatings

A novel silicon-containing trifunctional cycloaliphatic epoxide resin tri(3,4-epoxycyclohexylmethyloxy) phenyl silane (TEMPS) was synthesized and characterized by FTIR, ¹H NMR, ¹³C NMR, and ²⁹Si NMR spectroscopic analysis. A series of flame-retardant formulations by blending TEMPS with a commercial epoxide resin DGEBA (EP828) in different ratios were prepared, and exposed to a medium pressure lamp to form the cured films in the presence of diaryliodonium hexafluorophosphate salt as a cationic photoinitiator. The thermal degradation behaviors of the cured films were evaluated by thermogravimetric analysis. The char yields under nitrogen and air atmospheres increased along with the TEMPS content. The limiting oxygen index (LOI) value increased from 22 for EP828 to 30 for TEMPS80, demonstrating the improved flame retardancy. The data from the dynamic mechanical thermal analysis showed that TEMPS had good miscibility with EP828. The T _s and T _g both decreased from 93 and 138 to 78 and 118 °C, respectively. The crosslinking density (ν _e) increased along with the TEMPS content. The mechanical property measurements indicated that the addition of TEMPS led to a decrease in the tensile strength and an increase in the elongation-at-break.     

Surface modification of ammonium polyphosphate by kaolinite and the study on thermal decomposition behavior and flame-retardant performance

Journal of Thermal Analysis and Calorimetry - The surface of ammonium polyphosphate is modified by layered silicates (kaolinite or functionalized kaolinite). The thermogravimetric analysis data...     

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.