Polyphosphate Composites Research Articles

Self-extinguishing polyimide sandwiched separators for high-safety and fast-charging lithium metal batteries

Developing fast-charging lithium metal battery (LMB) with high specific capacity arouses enormous attentions. Unfortunately, during the operation of fast-charging LMB, substantial amount of Joule heat generated within battery often induces inhomogeneous heat accumulation that concomitantly deteriorates the lithium dendrite growth issues, resulting in rapid capacity fading and potentially fatal thermal runaway. It is critically essential to develop advanced separator that possesses high ionic conductivity, effective dendrite inhibition and self-extinguishing property for fast-charging LMB with high-safety. Here, we report a facile approach to fabricate polyimide composite separator (denoted as PIFAP), where the polyimide fiber (PIF) membrane is sandwiched by aerogel layers of polyimide/ammonium polyphosphate composite. Notably, compared with PIF, the PIFAP features significant enhancement in flame retardance, electrolyte affinity, electrolyte adsorption and ionic conductivity. Moreover, beneficiating from the aerogel layers with uniform nanopores of ∼100 nm, the optimized PIFAP separator can enable homogeneous lithium deposition, achieving a dendrite-free lithium deposition on the surface of anode for over 1600 h, superior to the PIF and Celgard separators. The resulting “LiFePO4/PIFAP/Li” cell can exhibit a remarkably high cycling stability with 99.1 % of capacity retention after long-term cycling at a current density of 10 C.

Broadband absorption of macro pyramid structure based flame retardant absorbers

• A flame retardant and microwave absorbing carbon nanotube/ammonium polyphosphate composite is prepared by a simple process. • The wave transparent flame retardant coating ensure the flame retardant and absorbing material not be ignited under open fire. • The the maximum absorption bandwidth can reach 14.36 GHz by the pyramid structure. • The designed pyramid structure can ensure the absorption bandwidth of 14 GHz at the incident angle within 60°. Flame-retardant materials with good electromagnetic wave absorption play an increasingly important role in Over-the-Air (OTA) tests in microwave anechoic chambers. In this work, carbon nanotubes and ammonium polyphosphate (CNTs@APP) composite were prepared by crosslinking with the silane coupling agent (KH550). The flame retardancy is improved with the increase of APP. However, the microwave absorption performance (MAP) and processing difficulty changed greatly as well. Therefore, magnesium aluminum double-layer metal hydroxide (LDH) was obtained by coprecipitation method and processing into the coating, so as to realize flame retardancy which reaches the limiting oxygen index (LOI) of 24.8% and good MAP at the same time. Then, a high-frequency structure simulator (HFSS™) was used to simulate the pyramid model to realize the broadband absorption, and the optimal parameter range was obtained, that is, when the total height of the material is 40 mm, the height of the base accounts for 1/5–1/3, and the tangent of the half top angle is near 1/5, which result in the best MAP. Finally, the broadband absorption of 14.36 GHz (3.64–18 GHz) was realized when the base height is 1/3, and the broadband absorption of 14 GHz (4–18 GHz) can be realized under the condition of large-angle oblique incidence of 0°–60°. Based on the pyramid structure of flame retardant absorbers, the obtained samples possess both good flame retardancy and microwave absorption, which show great application prospects in the field of OTA test, broadband microwave absorption performance, and brodaband oblique incidence absorption.

Synergistic Effects of Iron Alginate on Improving the Fire Safety and Mechanical Properties of Epoxy Resin/Ammonium Polyphosphate Composites

AbstractIron alginate is chosen as an eco‐friendly synergist to improve the flame retardancy, smoke suppression, and mechanical properties of epoxy resin/ammonium polyphosphate composites (EP/APP). The suitable additive amount of iron alginate further enhances the char‐forming ability in the higher‐temperature range and flame retardancy of EP/APP. EP/APP9.0‐iron alginate1.0 retains a char residue of 33.3% at 700 °C and obtains a limiting oxygen index value of 28.4% and vertical burning test (UL‐94) V‐0 rating, while EP/APP10 has no UL‐94 rating. The burning behaviors of EP/APP9.0‐iron alginate1.0 are also suppressed; and the total smoke production value is much lower than that of EP/APP10. EP/APP9.0‐iron alginate1.0 releases less smoke and flammable fragments. The suitable additive amount of iron alginate boosts the mechanical properties of EP/APP, while APP destroys the mechanical properties of EP. Therefore, the addition of suitable amount of iron alginates can further reduce the fire hazard, and improve the mechanical properties of EP/APP composites.

Preparation of Mn2+ Doped Piperazine Phosphate as a Char-Forming Agent for Improving the Fire Safety of Polypropylene/Ammonium Polyphosphate Composites.

A piperazine phosphate doped with Mn2+ (HP-Mn), as a new char-forming agent for intumescent flame retardant systems (IFR), was designed and synthesized using 1-hydroxy ethylidene-1,1-diphosphonic acid, piperazine, and manganese acetate tetrahydrate as raw materials. The effect of HP-Mn and ammonium polyphosphate (APP) on the fire safety and thermal stability of polypropylene (PP) was investigated. The results showed that the combined incorporation of 25 wt.% APP/HP-Mn at a ratio of 1:1 endowed the flame retardant PP (PP6) composite with the limiting oxygen index (LOI) of 30.7% and UL-94 V-0 rating. In comparison with the pure PP, the peak heat release rate (PHRR), the total heat release (THR), and the smoke production rate (PSPR) of the PP6 were reduced by 74%, 30%, and 70%, respectively. SEM and Raman analysis of the char residues demonstrated that the Mn2+ displayed a catalytic cross-linking charring ability to form a continuous and compact carbon layer with a high degree of graphitization, which can effectively improve the flame retardancy of PP/APP composites. A possible flame-retardant mechanism was proposed to reveal the synergistic effect between APP and HP-Mn.

Synergistic function of N‐P‐Cu containing supermolecular assembly networks in intumescent flame retardant thermoplastic polyurethane

AbstractThe design of high‐performance compounded flame retardants based on multielement can be of great significance for reducing the flammability of polymer materials. In this article, a new type of N‐P‐Cu containing supermolecular assembly network (MPCSN) flame retardant was prepared and subsequently added into thermoplastic polyurethane elastomer (TPU)/silicon microencapsulated ammonium polyphosphate (SiAPP) composites. The obtained results indicated that a series of TPU/SiAPP/MPCSN composites exhibited strong adhesions with the TPU matrix. Additionally, the thermal and flame retardant performances of TPU composites were markedly improved after the introduction of different proportions of SiAPP to MPCSN. For example, the peak of heat release rate, the total heat release, the peak of smoke production rate, the total smoke release of the TPU composite containing 7.5 wt% SiAPP and 2.5 wt% MPCSN (TPU/SiAPP3/MPCSN1) remarkably decreased by 68.7%, 52.9%, 52.4%, and 49.4%, respectively, besides the highest LOI value (27.5 vol%) and UL‐94 V‐0 rating, compared with those of pure TPU. The improved flame retardance of the TPU/SiAPP3/MPCSN1 composite was due to the explanations: On one hand, a compact intumescent char effectively protected the TPU matrix from heat and oxygen and retarded the gaseous products permeation into the combustion zone; on the other hand, evolved phosphorus‐containing free radicals captured the H• and HO• generated from the TPU material. The synergistic effect of SiAPP and MPCSN resulted in strong flame suppression, accompanied by 10.8% and 37.8% reductions in FIGRA and Av‐EHC, respectively. This article offers a facile approach to fabricate highly effective flame‐retardant TPU composites.

Effects of Maleic Anhydride Grafted Polypropylene on the Physical, Mechanical and Flammability Properties of Wood-flour/Polypropylene/Ammonium Polyphosphate Composites

In this study, maleic anhydride grafted polypropylene (MAPP) was incorporated as coupling agent in the wood-flour/polypropylene/ammonium polyphosphate composites (flame-retardant WPCs). The effects of MAPP content (5 wt.%, 10 wt.% and 15 wt.%) on the physical, mechanical and flammability properties of flame-retardant WPCs were investigated. The water soaking tests showed that the incorporation of MAPP could reduce the hygroscopicity of flame-retardant WPCs. The mechanical properties of WPCs were evaluated by three-point bending tests, unnotched Izod impact strength tests, and dynamic mechanical analysis. The results showed that the flame-retardant WPC containing 10 wt.% MAPP (WPC/APP/MAPP-10 %) performed the best flexural properties, the highest impact strength, E′ value, and tan δ at room temperature. The limiting oxygen index (LOI) tests and cone calorimetry tests showed that the incorporation of 10 wt.% MAPP endowed the flame-retardant WPC with the highest LOI value, the lowest peak-heat release rate, total heat release, CO/CO2 weight ratio and total smoke release. Moreover, the characterization of the WPCs combustion residues performed that WPC/APP/MAPP-10 % had the most complete carbonaceous structure with the highest graphitization degree after combustion. In general, the addition of 10 wt.% MAPP could impart the flame-retardant WPC with the optimum physical-mechanical properties and flame-retardant performance.

Flame retarded rigid polyurethane foam composites based on gel-silica microencapsulated ammonium polyphosphate

Microencapsulated ammonium polyphosphate (SiAPP) was prepared by sol-gel method with gel-silica as the shell material. And also, SiAPP was characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM), which confirmed the successfully fabrication of SiAPP. Furthermore, 30 php (parts per hundreds of polyol) SiAPP was introduced to prepare rigid polyurethane foam/microcapsulated ammonium polyphosphate composites (RPUF/SiAPP30). Flame retardancy, water resistance, physical properties and thermal stability of RPUF/SiAPP composites were compared with virgin RPUF and RPUF/APP composites. The results showed that RPUF/SiAPP30 which possessed excellent flame retardancy. Even after being immersed in water for 15 days, the underwriters laboratories vertical burning test (UL-94) of RPUF/SiAPP30 could pass V-1 rating with the limiting oxygen index (LOI) of 21.8 vol%, which was better that of RPUF/APP30. Compressive strength of RPUF/SiAPP30 was 0.292 MPa, which was 12.3% higher that of RPUF/APP30. SEM and Raman spectra confirmed that RPUF/SiAPP30 possessed more compact char residue with higher thermal resistance, which could inhibit mass and heat transmission in combustion. Consequently, a possible gas-solid flame-retardant mechanism of RPUF/SiAPP composite was proposed.

Preparation of melamine–formaldehyde resin-microencapsulated ammonium polyphosphate and its application in flame retardant rigid polyurethane foam composites

Melamine–formaldehyde resin-microencapsulated ammonium polyphosphate (MFAPP) was prepared by in situ polymerization using melamine–formaldehyde (MF) resin as the shell material. MFAPP was characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), which confirmed its successful fabrication. MFAPP was further introduced to prepare rigid polyurethane foam/microencapsulated ammonium polyphosphate composites (RPUF/MFAPP). The flame retardancy, water resistance, physical properties, and thermal stability of RPUF/MFAPP were compared with virgin RPUF and RPUF/APP composite. RPUF/MFAPP30 possessed excellent flame retardancy. Even after immersion in water for 15 days, RPUF/MFAPP30 achieved V-1 rating in UL-94 test with limiting oxygen index (LOI) of 21.3 vol%, which was better than that of RPUF/APP30 with equivalent APP loading. The compressive strength of RPUF/MFAPP30 was 0.295 MPa, which was 13.5% higher than that of RPUF/APP30. Thermogravimetric analysis-Fourier transform infrared spectroscopy (TGA-FTIR) was applied to investigate gaseous products of the decomposition process for RPUF/APP and RPUF/MFAPP. It was found that the intensities of CO2, isocyanate compounds, and CO for RPUF/MFAPP were lower than the values for RPUF/APP, indicating superior fire safety of RPUF/MFAPP. SEM and Raman spectra confirmed that RPUF/MFAPP30 possessed more compact char residue with higher thermal resistance, which was thus better able to inhibit mass and heat transmission in combustion. Consequently, a possible gas–solid flame-retardant mechanism of the RPUF/MFAPP composite was proposed.

Poly(diallyldimethylammonium) and polyphosphate polyelectrolyte complex as flame retardant for char-forming epoxy resins

The flame retardant poly(diallyldimethylammonium) and polyphosphate polyelectrolyte complex and the curing agent m-Phenylenediamine were blended into diglycidyl ether of bisphenol A (DGEBA)-type epoxy resin to prepare flame-retardant epoxy resin thermosets. The effects of poly(diallyldimethylammonium) and polyphosphate on fire retardancy and thermal degradation behavior of epoxy resins (EP)/poly(diallyldimethylammonium) and polyphosphate composites were tested by Limiting Oxygen Index, UL-94, cone calorimeter tests, and thermogravimetric analysis and compared with pure EP. The results showed that the Limiting Oxygen Index value of EP/poly(diallyldimethylammonium) and polyphosphate composite could reach 31.9%, and UL-94 V-0 rating at 10 wt% poly(diallyldimethylammonium) and polyphosphate loading. Meanwhile the cone calorimetry peak heat release rate and total heat release were reduced up to 55.2% and 21.8%, respectively; smoke production rate and total smoke production were also declined significantly, compared with those of pure epoxy resins. Poly(diallyldimethylammonium) and polyphosphate played a very good flame-retardant effect on epoxy resins.

Enhanced flame retardancy of unsaturated polyester resin composites containing ammonium polyphosphate and metal oxides

AbstractThree metal oxides (MOs) (Fe2O3, Sb2O3, Al2O3) were incorporated into blends of unsaturated polyester resin (UPR)/ammonium polyphosphate (APP) composites with the aim of studying and comparing their synergistic effect on flame retardancy with APP. The UPR‐APP/MOs composites were prepared, then the thermal stability and flame‐retardant properties of the UPR composites were evaluated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), vertical burning test (UL‐94), and cone calorimetry test (CCT). Besides, residues after CCT were characterized by scanning electron microscopy and laser Raman spectroscopy. The LOI values of the UPR composites with 0.5 wt% MOs increased to around 40%. However, the CCT results indicated that the incorporation of Sb2O3 brought an increase in the total heat release. Moreover, these three MOs had different effects on the process of thermal degradation of UPR composites from the TGA results. Based on the above results, Al2O3 provided a best promotion on flame retardancy among three MOs.

Study of the inhibitory ability of inorganic di- and polyphosphate compositions

The article considers the anticorrosive properties of inorganic di-and polyphosphate compositions in relation to St-3 steel, depending on the pH of the medium, the nature and concentration of phosphate, and the nature of the modifier ion. The research was conducted using GOST-based methods: gravimetry, potentiometry, photocolorimetry, infrared spectroscopy and scanning electron microscopy. On the basis of experimental data, quantitative indicators of corrosion process were determined: the rate of corrosion process, the degree of protection, the depth index, the coefficient of inhibition and the assessment of the stability of the formed film on the ball scale of corrosion resistance against steel. The analysis of experimental data allows to establish the influence of the above factors on the corrosion processes in the systems under study. The experimental data are supplemented by thermodynamic calculations of the corrosion process parameters, the results of which correlate well with the kinetic data of the process under study. In the course of the research work, the analysis of corrosion deposits was also carried out. The regularities established during the work contribute to the creation of effective di-and polyphosphate inhibitors with the highest degrees of protection.

Metal‐phenolic networks: A biobased synergist for EVA/APP composites toward enhanced thermal stability and flame retardancy

ABSTRACTIn the present study, a biomass‐derived metal‐phenolic networks (MPN) were used as charring agent and flame‐retardant synergist for Ethylene‐vinyl acetate/Ammonium polyphosphate (EVA/APP) composites. Compared with the polyphenol, the thermal stability of MPN was improved remarkably, making it a good match for EVA. Meanwhile, Limit oxygen index test revealed that MPN endowed EVA/APP composites with enhanced flame‐retardant performance. The reason on improvement in the flame retardancy of composites was also discussed and the corresponding mechanism was proposed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47243.

Effects of wool fibre and other additives on the flammability and mechanical performance of polypropylene/kenaf composites

Abstract Influence of wool fibres (WF) in improving the flame retardant and mechanical properties of polypropylene/kenaf fibre/intumescent ammonium polyphosphate (PP/KF/APP) composites is described. Flammability of PP/KF/APP/WF composite was evaluated using cone calorimetry, UL 94-V vertical burning tests and thermo-gravimetric analysis, and compared to results of similar composites which contained an ultraviolet ray stabiliser and colourant combination (PP/KF/APP/UVC). Tensile, bending and impact test analyses were also conducted on both sets of composites. PP/KF/APP/WF system had stable residual char at elevated temperatures, significantly improving fire protection. High degree of cross-linked stable char formation and residual char in PP/KF/APP/WF composite provided sufficient evidence of synergistic effect of wool. WF increased the tensile modulus of the composite by approximately 16%, while UVC (together with APP) improved the composite's flexural stiffness by 21%.

Effects of treated waste silicon rubber on properties of poly(lactic acid)/ammonium polyphosphate composites

ABSTRACTConsidering the massive waste silicone rubber composites (WSiRC) in electrical and electronic engineering industries every year, the utilization of WSiRC is a meaningful and urgent task. In this study, WSiRC was utilized after a simple treatment in the flame retardant polylactic acid (PLA). The TG data in N2 indicated that the char residues at 700 °C of the PLA/ammonium polyphosphate(APP)/WSiRC samples are improved with the loading of WSiRC, which means that WSiRC could act as the carbonization promoter for the PLA blends. Moreover, it is found in LOI, UL94, and cone tests that WSiRC can only improve the flame retardancy of PLA in an appropriate loading range since the crosslink structure formed by WSiRC may interact with that formed by APP and jointly improve the char‐formation ability of PLA. However, too much WSiRC deteriorated the flame retardancy of PLA because of the effect of WSiRC cluster at its higher loading. The photographs of the char residue after the cone tests also manifested that. The cone data showed that WSiRC could suppress the production of smoke as well. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45231.

Improved self-supporting property of ceramifying silicone rubber composites by forming crystalline phase at high temperatures

Abstract Ceramic-like residues were obtained by firing silicone rubber (SiR)/ammonium polyphosphate (APP) composites both with and without magnesium hydroxide (MH) composites at different temperatures. To evaluate the self-supporting property, the bending angles of the residues were tested. The effect of MH and firing temperatures on the self-supporting property was investigated. Results show that the addition of MH reduces the bending angles of the residues and improves their densification. Furthermore, as temperature increases, the bending angles of the residues containing magnesium decrease and their flexural strength is improved. Infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analyses demonstrate that formation of crystalline magnesium pyrophosphate within the residues is due to interaction between MH and APP, and the relative content of the crystalline phase increases with increasing temperatures. Solid-state nuclear magnetic resonance (SNMR) further confirms the phosphates, but the above crystalline phase also amorphous magnesium orthophosphate and magnesium metaphosphate. Moreover, as temperatures increase, the relative content of the crystalline phase is improved, which agrees well with the XRD analysis. Therefore, the crystalline phase formed at high temperatures plays a main role in the improvement of the self-supporting property.

Flammability and flame‐retardant mechanism of high density polyethylene/wood fiber/modified ammonium polyphosphate composite

Fabrication and characterization of a novel high density polyethylene/wood fiber/modified ammonium polyphosphate (HDPE/WF/MAPP) composite have been carried out. The flammability of the composite is characterized by the limiting oxygen index (LOI), vertical burning test (UL‐94), and cone calorimetry. The flame‐retardant mechanism is investigated by Fourier transform‐infrared (FT‐IR), X‐ray photoelectron spectroscopy (XPS), and scanning electronic micrograph (SEM).The results indicate that, with the optimum formulation, the LOI and UL‐94 of the HDPE/WF/MAPP composite are 38.0% and V‐0 rating, respectively. Comparing with HDPE/WF, the peak of heat release rate (PHRR) of the HDPE/WF/MAPP composite decreases from 432 to 166 kW m−2, and total heat release (THR) decreases from 66 to 33 MJ m−2. Cone calorimeter analysis suggest that the smoke production rate (SPR), total smoke production (TSP), mass loss rate (MLR), and time to ignition (TTI) of the HDPE/WF/MAPP system significantly decrease. In addition, the thermal stabilities of the composite are studied by thermo gravimetric analysis (TGA), which shows there are two stages decomposition during the thermal degradation process. With the addition of MAPP, char residue of the composite increase from 12.06% to 34.67%. The char residue containing P‐OH, P‐N‐C, P‐O‐P, P‐O‐C, and aryl groups can directly affect the flame retardance. The flexural modulus of the HDPE/WF/MAPP system is improved greatly in the presence of MAPP. POLYM. COMPOS., 39:1192–1199, 2018. © 2016 Society of Plastics Engineers

Thermal Decomposition of Ammonium Polyphosphate-Polyurethane Composite Foam Brown by H<sub>2</sub>O

Abstract: Ammonium polyphosphate-polyurethane foam composite (APP-PUF) was prepared from poly(adipate)diol/ammonium polyphosphate composite (f = 2), polyether polyol (f = 4.6), and PMDI (f = 2.5). As a blowing agent, H 2 O wasused at various concentrations. The thermal decomposition behavior, morphology, closed-cell content, and density of APP-PUF were characterized. At the H 2 O concentrations lower than 3.5 php, the cell size of pure polyurethane foams (PUF) andAPP-PUFs were close each other. As the H 2 O concentration became greater than 5.0 php, the cell size of the PUFs greatlyincreased compared to that of APP-PUFs. Addition of 1.5~1.9 wt% ammonium polyphosphate to the PUFs greatly enhancedthe thermal stability of the PUFs, so 50 wt% residual temperature of APP-PUFs increased to 380~488°C, which were30~70°C higher than those of the PUFs. Thermal stability of the PUFs and APP-PUFs increased with H 2 O content and thendecreased once H 2 O content exceeded 5 php.Keywords: polyurethane foam composite, ammonium polyphosphate, TGA, thermal decomposition

Microencapsulated ammonium polyphosphate and its application in the flame retardant polypropylene composites

In this article, a novel intumescent alumina–silica hydrogel double shell microencapsulated ammonium polyphosphate flame retardant is prepared and filled into polypropylene as a flame retardant. The structure and properties of alumina–silica hydrogel double shell microencapsulated ammonium polyphosphate are characterized by Fourier transform infrared, scanning electron microscopy, and thermogravimetric analysis. The results show that the Al and Si groups are attached to the surface of ammonium polyphosphate. The flame retardancy, morphology of char layers, thermal properties, and mechanical properties of the polypropylene/alumina–silica hydrogel double shell microencapsulated ammonium polyphosphate composites are evaluated by limiting oxygen index, UL-94 test, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, and mechanical properties test. The results show that alumina–silica hydrogel double shell microencapsulated ammonium polyphosphate can improve the thermal stability and charred residues at high temperature. In addition, the combination of alumina–silica hydrogel double shell microencapsulated ammonium polyphosphate and polyamide 6 shows more compact, firm, and continuous charred layers, resulting in better flame retardant performances. The limiting oxygen index value for polypropylene/alumina–silica hydrogel double shell microencapsulated ammonium polyphosphate/polyamide 6 composites can reach 25.6 and obtain a UL-94 V-0 rating. Also, polypropylene/alumina–silica hydrogel double shell microencapsulated ammonium polyphosphate/polyamide 6 composites present better mechanical properties than polypropylene/ammonium polyphosphate/polyamide 6 composites at the same content of flame retardant and polyamide 6.

Flame‐retardant properties of ethylene‐vinyl acetate/oil sludge/ammonium polyphosphate composites

Oil sludge (OS) containing a lot of CaCO3 is a large quantity waste product in the production of oil. OS was used as a material to synthesize the ethylene‐vinyl acetate (EVA)/OS/ammonium polyphosphate (APP) composites. The synergistic flame retardant effects between OS and APP in EVA composites were studied using limiting oxygen index (LOI), cone calorimeter test (CCT), scanning electronic microscopy (SEM), smoke density test (SDT), and thermogravimetry‐Fourier transform infrared spectrometry. The results showed that the addition of a given amount of APP apparently increased the LOI value. The CCT data indicated that heat release rates (HRR) of EVA/OS/APP composites decreased greatly in comparison with that of EVA and EVA/OS composites. The morphology and structures of residues investigated by SEM gave positive evidence that char layers formed from the EVA/OS/APP composites were more compact than that from the EVA/OS composites. The SDT results showed that APP was helpful to smoke suppression. The TG‐FTIR is used to characterize the thermal degradation mechanism of samples and the volatilized products formed on the thermal degradation. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1731–1739, 2015

Computer simulation study on the compatibility of cyclotriphosphazene containing aminopropylsilicone functional group in flame retarded polypropylene/ammonium polyphosphate composites

Abstract The compatibilization of cyclotriphosphazene N3P3[NH(CH2)3Si(OCH2CH3)3]6 (APESP) in flame retarded polypropylene (PP)/ammonium polyphosphate (APP) composites was investigated by atomistic and mesoscale simulations. Molecular dynamics (MD) and dissipative particle dynamics (DPD) simulation method were used to study the binding energy (Ebinding), radius distribution function, hydrogen bond, Flory–Huggins parameter (χ) and mesoscopic morphology of the composites. It was found that the compatibility of APP in PP matrix significantly got better due to the loading of the cyclotriphosphazene derivative APESP, compared with the loading of γ-aminopropyltriethoxysilane (APES) or hexachlorocyclotriphosphazene. The Ebinding value of APP and PP increased to 161.45 kJ/mol in PP/APP/APESP, in contrast to 2.82 kJ/mol in PP/APP. Furthermore, the last frame of MD profiles indicated the presence of strong hydrogen bond between APP and APESP molecules. The DPD data showed that APESP made the dispersion and distribution of APP in PP matrix more homogeneous because of improved interfacial interaction. To verify the simulation results, the PP/APP, PP/APP/APES and PP/APP/APESP composites were prepared to analyze mechanical properties, morphologies and flame retardancy. Elongation at break of PP/APESP/APP was 334.79%, nearly four times as much as that of PP/APP. Scanning Electron Microscope (SEM) microphotographs indicated that the dispersion of APP in PP matrix was improved because of the loading of APESP. At the same time, LOI value of the composites with APESP levelled up from 21.7% to 26.5%, and UL 94 rating reached to V-2. The above experimental data demonstrated that the simulation strategy in this investigation is an effective path for molecular design and performance prediction of the flame retarded systems.