Shaoxiang Li

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.

Flame retardant epoxy resin based on bisphenol A epoxy resin modified by phosphoric acid

Flame retardant epoxy resin (FREP) were synthesized from phosphoric acid and bisphenol A epoxy resin (BAEP). The structure of the FREP was characterized using FTIR and 31P NMR. Then, several FREP/BAEP mass ratios were used to obtain materials with different phosphorus contents. The properties of the thermosetting materials were evaluated by limiting oxygen index, UL 94, cone calorimeter test, and thermogravimetric analysis. The results showed that the heat release rates and smoke production rates decreased greatly, and char residue increased with the increasing of FREP. It indicates that good flame retardant properties are related to the formation of a protective phosphorus-rich char layer.

Fire hazard reduction of hollow glass microspheres in thermoplastic polyurethane composites

Nowadays, reducing the fire hazard of thermoplastic polyurethane (TPU) is an important research direction in the fields of fire safety materials. In this article, hollow glass microsphere (HGM) was used to reduce the fire hazard of TPU in combustion process. The fire characteristics including smoke and heat production of TPU composites were evaluated using smoke density test (SDT) and cone calorimeter test (CCT). And the thermal decomposition and flammable properties were further studied using thermogravimetric analysis/infrared spectrometry (TG-IR) and limiting oxygen index (LOI), etc. The SDT results showed that the luminous flux (LF) of TPU4 containing 2.00wt% HGM was up to 24% at the end of test without flame, which is much higher than that of TPU0 (5%). And, the CCT results indicated that 2.00wt% HGM could make the total smoke release (TSR) decrease from 1019m2/m2 (TPU0) to 757m2/m2 (TPU4), reduced by 26%. The TG-IR results confirmed that HGM could improve the thermal stability of composites and reduce the production of some toxic gases. The above results illustrated HGM had a good prospect in reducing the fire hazard for TPU.

Fire safety improvement of para-aramid fiber in thermoplastic polyurethane elastomer

This article mainly studied fire safety effects of para-aramid fiber (AF) in thermoplastic polyurethane (TPU). The TPU/AF composites were prepared by molten blending method, and then the fire safety effects of all TPU composites were tested using cone calorimeter test (CCT), microscale combustion colorimeter test (MCC), smoke density test (SDT), and thermogravimetric/fourier transform infrared spectroscopy (TG-IR). The CCT test showed that AF could improve the fire safety of TPU. Remarkably, the peak value of heat release rate (pHRR) and the peak value of smoke production rate (pSPR) for the sample with 1.0wt% content of AF were decreased by 52.0% and 40.5% compared with pure TPU, respectively. The MCC test showed that the HRR value of AF-2 decreased by 27.6% compared with pure TPU. TG test showed that AF promoted the char formation in the degradation process of TPU; as a result the residual carbon was increased. The TG-IR test revealed that AF had increased the thermal stability of TPU at the beginning and reduced the release of CO2 with the decomposition going on. Through the analysis of the results of this experiment, it will make a great influence on the study of the para-aramid fiber in the aspect of fire safety of polymer.

Smoke suppression and synergistic flame retardancy properties of zinc borate and diantimony trioxide in epoxy-based intumescent fire-retardant coating

In this article, smoke suppression and synergistic flame retardancy properties of zinc borate (ZB) and diantimony trioxide (Sb2O3) in epoxy-based intumescent fire-retardant (IFR) coating were investigated based on cone calorimeter test, smoke density test, scanning electron microscopy, thermogravimetric and Fourier transform infrared spectroscopic analyses. The measurement results of the dynamic combustion and smoke production behaviors and static smoke production behaviors of these IFR coatings showed that the values of heat release rate, smoke production rate, smoke factor and fire growth index all decreased significantly with the addition of ZB and Sb2O3. At the same time, the specific optical densities were remarkably reduced due to the existence of ZB and Sb2O3. These attractive data clearly demonstrated that the ZB and Sb2O3 had a good effect on smoke suppression and synergistic flame retardancy of the IFR coating. Besides, the scanning electron microscopy and the infrared spectroscopic analyses during coating thermal degradation were also carried out to explore the outstanding synergistic smoke suppression and flame retardancy mechanism of ZB and Sb2O3. With the melt of ZB and Sb2O3, a lot of heat was absorbed, and then, the glassy protective layer associated with the graphite char would effectively retard heat and suppress smoke.

Influence of T31 content on combustion and thermal degradation behaviors on flame-retardant epoxy composites

To study the influence of the T31 content on the combustion properties and thermal degradation behaviors of flame-retardant epoxy composites, a series of flame-retardant epoxy composites were prepared using E-44 epoxy resin as matrix, T31 curing agent as curing agent, and intumescent flame retardant (IFR, based on phosphorus acid, melamine, and pentaerythritol) as flame retardant. The influence of T31 content on combustion behaviors and thermal degradation properties of the flame-retardant epoxy composites were studied using cone calorimeter test (CCT) and thermal-gravimetric analysis (TG), respectively. The cone calorimeter test results indicate that the decrease of T31 can significantly decrease the HRR, THR, SPR, and enhance the char residue of the epoxy composites. EP-4 with 7.0 wt% T31 shows the lowest HRR, SPR and the highest char residue. Furthermore, the TG results indicate that the EP-4 has the highest char residue among all the epoxy composites.

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.

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.