Yi Qian

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

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

Combustion behavior and thermal pyrolysis kinetics of flame-retardant epoxy composites based on organic–inorganic intumescent flame retardant

A novel organic–inorganic intumescent flame retardant, expandable graphite modified with charring agent (EGM), was synthesized using expandable graphite (EG), phosphorus oxychloride, and pentaerythritol. Then, EGM was used as flame retardant for epoxy resin. And the flame-retardant properties of epoxy composites were investigated by cone calorimeter test (CCT). The thermal degradation behaviors of epoxy composites were studied by thermogravimetric analysis (TG) in nitrogen atmosphere. And the pyrolysis kinetics of the composites was investigated using Kissinger and Flynn–Wall–Ozawa methods. The CCT result indicated that EGM can reduce the heat release rate and smoke production rate more than EG in flame-retardant epoxy composites: a more compact char residue formed on the surface of the sample with EGM than that of the sample with EG during the combustion process. The TG result showed that the sample with EGM has higher thermal stability than the sample with EG. And the data calculated from Kissinger and Flynn–Wall–Ozawa methods showed that both EP-0 and EP-3 had two thermal degradation stages; EGM can improve the Ea value of epoxy resins.

Synergistic flame-retardant effects between aluminum hypophosphite and expandable graphite in silicone rubber composites

The main aim of this work was to investigate the synergistic effect of expandable graphite (EG) and aluminum hypophosphite (AHP) on the flame retardancy of silicone rubbers (SR). The synergistic effects of EG with AHP in halogen-free flame-retardant SR composites have been studied by cone calorimeter test (CCT), thermogravimetric analysis (TG), and the thermogravimetric analysis/infrared spectrometry (TG–IR). The CCT results showed that AHP and EG can effectively reduce the flammable properties including peak heat release rate, total heat release, smoke production rate, total smoke release, and smoke factor. An improvement of thermal stability of SR/AHP/EG was also observed. The experimental observations from digital photographs give positive evidence of the synergistic effects between AHP with EG. The TG results reveal that SR/AHP/EG samples show slower thermal degradation rate and higher thermal stability at high temperature than SR sample. The TG–IR results showed that the addition of AHP and EG significantly decreased the combustible gaseous products such as hydrocarbons. These attractive features of SR/AHP/EG suggest that the method proposed herein is a good approach to prepare very effective flame retardants and corresponding super flame-retarding SR.

Influence of ferrite yellow on combustion and smoke suppression properties in intumescent flame-retardant epoxy composites

A series of intumescent flame-retardant epoxy resins (IFREP) were prepared based on bisphenol A epoxy resin (EP) as matrix resin, ammonium polyphosphate (APP) and pentaerythritol as intumescent flame retardants (IFRs), and ferrite yellow (goethite) as smoke suppressant. Then, the synergistic flame-retardant and smoke suppression properties of α-FeOOH on IFR epoxy composites were intensively investigated using cone calorimeter test and scanning electron microscopy. The thermal degradation process of IFR epoxy composites were studied using thermogravimetric analysis–infrared spectrometry under nitrogen atmosphere. Then, the pyrolysis kinetics parameters were investigated using Kissinger and Flynn–Wall–Ozawa methods. The results showed that goethite can significantly reduce heat release rate, total heat release, smoke production rate, and total smoke release. There are obvious synergistic flame-retardant and smoke suppression effects between goethite and IFRs in epoxy composites.

Combustion properties and pyrolysis kinetics of flame-retardant polyurethane elastomers

Flame-retardant polyurethane elastomers (PUEs) have been prepared using trichloroethyl phosphate (TCEP) as flame retardant. The combustion performances and thermal decomposition properties of PUEs were studied using cone calorimetry test and thermogravimetric analysis, respectively. Kissinger method and Flynn–Wall–Ozawa (FWO) method were adopted to discuss the pyrolysis kinetics of PUEs. The experimental results showed that TCEP has good flame-retardant effect for PUE. With the increase of TCEP, the peak heat release rate and total heat release values decrease. A good diagram of linear regression can be obtained from both Kissinger and FWO methods. The activation energy values of flam- retardant PUE can be calculated from FWO method at different conversion rates.

Preparation of mesoporous silica-LDHs system and its coordinated flame-retardant effect on EVA

This paper mainly studies synergistic flame-retardant effects and smoke suppression properties of mesoporous silica-LDHs system on the ethylene-vinyl acetate copolymer (EVA). The mesoporous silica-LDHs/EVA composites were prepared based on EVA as resin matrix, mesoporous silica-LDHs as flame-retardant composites. The flame-retardant and thermal degradation properties of the composites were characterized by limiting oxygen index (LOI), cone calorimeter test, scanning smoke density test (SDT), electronic microscopy (SEM) and thermogravimetry–Fourier transform infrared spectrometry (TG-IR) analysis. Remarkably, addition of certain amount of mesoporous silica-LDHs could evidently increase LOI values. The heat release rate and the total heat release of the composites were much lower than of pure EVA. The SDT results showed that the composites containing mesoporous silica-LDHs produced less smoke than pure EVA for a period of time. The morphologies and structures of the residues, revealed by SEM, ascertained that the formed char layers on the composites were denser than that of the LDHs/EVA composites. Mesoporous silica in the material can help smoke suppression. TG-IR data reveal that the incorporation of mesoporous silica-LDHs promoted the release of H2O, and CO2, meanwhile reduced harmful gases release.

Synergistic flame retardant effect between nano-silicon dioxide and layered double hydroxides in ethylene vinyl acetate composites

Layered double hydroxides (LDHs) were synthesized by a coprecipitation method. The synergistic flame retardant effect of nano-silicon dioxide (nano-SiO2) on ethylene vinyl acetate (EVA)/LDHs composites was studied using limiting oxygen index (LOI), cone calorimeter test (CCT), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Results showed that the LOI values of the EVA/LDHs/nano-SiO2 composites were basically higher than that of the EVA/LDHs composite, and the EVA composite with 48% LDHs and 2% nano-SiO2 reached an LOI value of up to 31.2%. The CCT results indicate that the addition of nano-SiO2 greatly reduced the heat release rate, total heat release, mass loss, smoke production rate, total smoke release, and smoke factor. The morphology and structures of residues investigated by SEM gave positive evidence that char layers formed from the EVA/LDHs/nano-SiO2 composites were improved. The TGA data showed that the EVA/LDHs/nano-SiO2 composites show a higher thermal stability than the EVA/LDHs composites.

Synthesis of TPU/TiO2 nanocomposites by molten blending method

Efficient flame-retardant TPU/TiO2 nanocomposites were synthesized by molten blending method. The morphological and structural analysis indicated that TiO2 nanoparticles could be well dispersed in TPU and increased compatibility with the polymer. The obtained mechanical and thermal data suggested that intense cross-linking interaction between TiO2 and TPU promoted more stable network structure, which increased tensile length at break, storage modulus and loss modulus and thermal stability. Furthermore, the cone results demonstrated that TiO2 could not only decrease HRR, but also provide more stable char due to its high heat resistance, and catching and isolating oxygen molecules. Though ignition was inevitably earlier and peak value appearance caused transient thermal conductivity, TiO2 could greatly deplete combustible smoke particulates on the surface of TPU by accelerating degradation of combustible gases to prevent further penetration and destruction from TPU surface as oxygen insulation barrier. Therefore, TiO2 as a kind of effective flame-retardant and smoke suppression material can be applied in the flame retardancy of TPU.

Combustion behavior and thermal stability of ethylene-vinyl acetate composites based on CaCO3-containing oil sludge and carbon black

CaCO3-containing oil sludge (OS) is a by-product from petroleum industry, with great amount of production. Therefore, an effective processing methods for CaCO3-containing OS is urgently needed. Herein, ethylene-vinyl acetate (EVA) composites based on CaCO3-containing OS and carbon black (CB) were prepared by melt blending method. The combustion behavior and thermal stability of flame-retardant EVA/OS/CB composites were investigated by cone calorimeter test, limiting oxygen index (LOI), scanning electron microscopy (SEM), smoke density test (SDT), and thermogravimetry-Fourier infrared spectrometry. The heat release rate and smoke production rate of the ternary composites containing 3% CB significantly decreased compared with the EVA/OS composites and pure EVA. Moreover, addition of a certain amount of CB could evidently increase LOI values. The morphologies and structures of the residues, revealed by SEM, ascertained that a better carbonaceous protective layer was formed on the ternary composites than the EVA/OS composite. It was obtained from SDT that CB in the material could retard the smoke production with the application of the pilot flame. The EVA/OS/CB composites assumed a higher thermal stability than the EVA/OS composites and pure EVA.