Flame Retardancy Of Polystyrene Research Articles

MXene-coated polystyrene microparticles for amorphous photonic crystal coating with enhanced color saturation, flame retardancy, and electromagnetic interference shielding

To enhance the color saturation of the amorphous photonic crystal (APC) coating composed of polystyrene (PS) microparticles, MXene nanosheets were deposited on the surface of the PS microparticles through strong electrostatic attraction. Three distinct colored APC coatings were achieved using Mayer rod-coating methods, employing PS microparticles of varying sizes. The intrinsic black nature of MXenes results in these coatings exhibiting high brightness of structural colors under ambient lighting conditions. Additionally, the three distinct colored APC coatings demonstrate high color saturation and low angular dependence. The thermal stability and flame retardancy of PS and PS@MXene microparticles with different MXene content were investigated. PS@MXene microparticles (three different diameters) containing 5 wt% MXene exhibited char residues of 11.0, 8.7, and 6.7 wt% at 700 °C during decomposition, whereas pure PS microparticles showed a char residue of <1.7 wt%. The peak heat release rate and total heat release of the PS@MXene microparticles were lower than those of pure PS, as characterized by a microscale combustion calorimeter. Furthermore, crack-free APC coatings on a black polyurethane substrate were successfully prepared using the Mayer rod-coating method, assisted by polyacrylic acid and ethylene glycol. The APC coatings containing PS@MXene microparticles with 5 wt% MXene, deposited on the surface of the polyurethane film, demonstrated shielding performances of approximately 20 dB. This work presents a straightforward and environmentally friendly method for constructing multifunctional APC coatings.

A novel halogen-free flame-retardant fabrication for the study of smoke suppression and flame retardancy of polystyrene

A novel P–N flame-retardant (PON) was synthesized by nucleophilic substitution reaction using diphenyl phosphoryl chloride and piperazine as raw materials. Its chemical structure was characterized by Fourier transform infrared spectroscopy (FTIR), liquid-state nuclear magnetic resonance (NMR), high resolution mass spectrometry (HEMS) and elemental analysis, and its thermal stability by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Subsequently, five char-forming agents, namely pentaerythritol (PER), chitosan (CTS), lignin (LI), graphene (GN) and expandable graphite (EG), were selected to form five intumescent flame-retardants in a 1:1 mass ratio with PON. Polystyrene (PS) composites were prepared by melt blending method. The synergistic effect of PON and different char-forming agents on thermal stability, combustion behavior and flame retardancy of PS composites were systematically investigated. The results showed that the PS/10% PON/10% EG composite had the highest limiting oxygen index (LOI) value of 25.8%, and the cone calorimetric test showed that the peak heat release rate (pHRR), total heat release rate (THR), and total smoke release (TSP) of the composite were reduced by 74.6%, 24.4% and 43.6%, respectively, compared with neat PS, and this composite exhibited the most excellent flame retardancy. Finally, the flame-retardant mechanism of PS/10% PON/10% EG composite was discussed and proposed by the results of scanning electron microscope (SEM), thermogravimetric analysis coupled to Fourier transform infrared spectroscopy (TG-IR), and pyrolysis-gas chromatography-mass (PY-GC/MS) measurements in detail.

Preparation and thermal properties of a novel DOPO‐based Schiff base derivative as a flame retardant for polystyrene

AbstractWe synthesized an acrylic acid 4‐[(10‐oxo‐10H‐9‐oxa‐10λ5‐phospaphenanthren‐10‐yl)‐phenylamino‐methyl]‐phenyl ester (DOPO‐AC), a novel Schiff base derivative based on 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide, and evaluated its utility as a flame retardant for polystyrene (PS). The synthesized DOPO‐AC was characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance spectroscopy, and high‐resolution mass spectrometry. The reactive vinyl groups of DOPO‐AC further copolymerized with styrene to produce PS/DOPO‐AC. Thermogravimetric analysis showed that DOPO‐AC could clearly improve the char residue formation. By comparing the data of T5% and T10%, it was found that the thermal stability of the PS/DOPO‐AC copolymer was reduced. We investigated the influence of DOPO‐AC on the flame retardancy of PS by determining limiting oxygen indexes, conducting vertical burning tests (UL‐94), and carrying out thermogravimetry combined with differential thermal analysis. These results revealed that PS containing 5 wt% DOPO‐AC had a UL‐94V‐0 rating and a limiting oxygen index of 29.6%. Residues of PS/DOPO‐AC copolymer after the UL‐94V tests were analyzed by scanning electron microscopy, X‐ray photoelectron spectroscopy, and FTIR spectroscopy; and the results allowed us to propose a flame retardant mechanism for PS/DOPO‐AC copolymer. Taken together, our results prove that DOPO‐AC is an effective flame retardant for PS.

Novel graphite-like carbon nitride/organic aluminum diethylhypophosphites nanohybrid: Preparation and enhancement on thermal stability and flame retardancy of polystyrene

Graphite-like carbon nitride (g-C3N4) was innovatively modified by diethylphosphinic acid through hydrogen bonding; g-C3N4/organic aluminum diethylhypophosphites (g-C3N4/DAHPi) hybrid (denoted as CDAHPi) was synthesized by salification reactions, and subsequently incorporated into PS matrix to prepare composites through melt blending method. Thermal data showed that g-C3N4 could protect DAHPi from external heat, leading to improved thermal stability of DAHPi. Moreover, it was found that the introduction of the hybrid reduced the values of heat release rate (HRR) and total heat release (THR) of the composites. Compared with those of pure PS, the HRR and THR of PS/CDAPHi4 decreasing by 43% and 21% respectively were observed at loadings as low as 4.0wt%. The PS/CDAHPi exhibited an additional advantage in suppression of pyrolysis gas production in comparison with neat PS. In addition, the additive showed higher interfacial adhesion with PS.

Enhanced thermal stability and flame retardancy of polystyrene by incorporating titanium dioxide nanotubes via radical adsorption effect

Titanium dioxide nanotubes (TNTs) were synthesized by a hydrothermal method and then incorporated into polystyrene (PS) through in situ bulk radical polymerization. In comparison, the PS/TiO2 composites with various TiO2 loadings were also prepared by melt blending method. The addition of TNTs induced a significant thermal stabilization on PS: with the 5 wt% loading of TNTs, the corresponding T−10% and Tmax of the composite were improved by 41 and 58 °C compared to those of pristine PS. Meanwhile, an approximately 33% reduction in peak heat release rate was observed in the case of PS/TNTs5%. In contrast, TiO2 did not exhibit so effective enhancement in thermal stability and flame retardancy as TNTs. Direct pyrolysis-mass spectrometry and thermo-gravimetric analysis/infrared spectrometry analysis showed that the radical adsorption effect of TNTs was responsible for the improved thermal stability and flame retardancy of polystyrene.

The influence of typical layered inorganic compounds on the improved thermal stability and fire resistance properties of polystyrene nanocomposites

Organic‐modified montmorillonite (OMMT), organic‐modified layered double hydroxide (SDS‐LDH) and graphene (GNS) were three typical layered inorganic compounds. The polystyrene (PS) nanocomposites were prepared using in situ polymerization method. X‐ray diffraction, transmission electron microscopy, thermogravimetric analysis, and microscale combustion calorimeter were used to investigate the morphology and microstructure, thermal stability, and combustion performance of the PS nanocomposites. It was evident that the addition of the typical layered inorganic compounds could improve thermal stability and flame retardancy of PS. The results revealed that organic‐modified layered double hydroxide and graphene were dispersed in PS matrix with mainly exfoliated structure, whereas OMMT distribution with intercalated and few exfoliated structure. The PS/OMMT nanocomposites exhibited superior flame retardance over PS/SDS‐LDH and PS/GNS. Compared to pure PS, a 25% decrease in the peak heat release rate value was obtained for PS nanocomposites containing 3.0 wt% OMMT. The thermogravimetric analysis results demonstrated that the addition of OMMT led to the improvements in the thermal stability and char residues of the PS nanocomposites, especially the T−50% and Tmax of the PS/5.0 wt% OMMT nanocomposites had improved by 38°C and 63°C, respectively, compared to those of pure PS. The improvement of thermal stability and fire resistance properties was primarily attributed to the physical barrier effect of layered inorganic nanosheets and the catalytic carbonization behavior of layered double hydroxide. POLYM. COMPOS., 38:E320–E330, 2017. © 2015 Society of Plastics Engineers

Microwave-assisted synthesis of SiO2 nanoparticles and its application on the flame retardancy of poly styrene and poly carbonate nanocomposites

Various morphologies of silica nanoparticles were synthesized by a microwave-assisted Pechini method. Silica nanostructures were synthesized via a fast reaction between tetra ethyl ortho silicate and ammonia at presence citric acid and other effective agents in Pechini procedure. Then for preparation of polymer-matrix nanocomposites, SiO2 nanoparticles were added to poly carbonate (PC) and poly styrene (PS) matrices. Nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR). The influence of SiO2 nanostructures on the flame retardancy of the polymeric matrix was studied using UL- 94 analysis. Our results show that the SiO2 nanostructure can enhance the flame retardant property of the poly carbonate matrix. PC shows better flame retardancy compare to poly styrene.

Efficiency of wollastonite and ammonium polyphosphate combinations on flame retardancy of polystyrene

The thermal and fire properties of polystyrene (PS) flame retarded by a system composed of ammonium polyphosphate (APP) and wollastonite (W) were investigated by thermogravimetric analysis, pyrolysis‐combustion flow calorimeter, pyrolysis gas chromatography mass spectrometry, cone calorimetry and epiradiator. The combustion residues were observed by scanning electron microscopy/energy dispersive X‐ray spectroscopy and analyzed by X‐ray diffraction. The combination of both additives enables increasing the thermal stability of PS while increasing simultaneously the high temperature residue. The peak of HRR was also significantly reduced while time to ignition varied depending on the composition. It was shown that the degradation pathway of PS was affected by the presence of the additives implying a reduction of the effective heat of combustion. In the condensed phase, APP decomposition promotes char formation and favors the reactivity between phosphorus and silicate. A layer composed of char, W and a mixture of calcium and silicon phosphate is formed at the sample surface during combustion. This layer is cohesive enough to limit the release of combustible gases to the gas phase. Moreover, the thermally stable protective layer reaches high temperature enabling the re‐irradiation of a part of the incident heat flux. The flame retardancy of PS is thus enhanced. Copyright © 2012 John Wiley &amp; Sons, Ltd.

The application of Ce‐doped titania nanotubes in the intumescent flame‐retardant PS/MAPP/PER systems

In this work, we reported the synthesis, characterization of Ce‐doped titania nanotubes (Ce‐TNTs), and application in flame retardancy of an intumescent flame‐retardant polystyrene (PS/IFR) system. The flame retardancy of polystyrene (PS) composite that was composed of pentaerythritol, microencapsulated ammonium polyphosphate, and PS was enhanced significantly by adding a small amount (0.1 wt%) of (Ce‐TNTs). The thermal properties of the flame‐retardant PS were investigated by thermogravimetric analysis, limiting oxygen index (LOI), vertical burning test (UL‐94), scanning electronic microscopy, dynamic mechanical thermal analysis, and the real‐time Fourier transform infrared spectrometry (FTIR). The maximal decomposition rate temperature of PS/IFR containing Ce‐TNTs in air is much higher than that of other PS composite without Ce‐TNTs. The LOI value of PS/IFR that contained 0.1 wt% of Ce‐TNTs was increased from 27.0 to 28.5, and the UL‐94 rating was also enhanced to V‐0 from no rating when the total loading of additive was the same. The real‐time FTIR showed that the degradation process was changed after the addition of TNTs. All results indicated that Ce‐TNTs had a significant synergistic effect on the flame retardancy of PS/IFR. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Mechanism on flame retardancy of polystyrene/clay composites-The effect of surfactants and aggregate state of organoclay

Effects of organically modified montmorillonites (OMMTs) with different type and amount of modifiers on flame retardancy of polystyrene (PS) have been studied. The results from morphology analysis, gas chromatography–mass spectrometry and cone calorimeter have showed different mechanisms for the flame retardancy of PS/OMMTs composites, depending on surface property of OMMTs. One is the catalysis of acid sites formed on the surface of octadecylammonium modified MMT (c-MMT) via Hoffman decomposition on the carbonization of degradation products, which promotes the formation of clay-enriched char barrier. The other is related to chemical effect of inherent properties of MMT sheets on reactive intermediates during combustion, which work in PS/Na-MMT and PS/sodium dodecylsulfonate modified MMT (a-MMT) composites. Furthermore, the effect of the aggregate states of a-MMT on the flame retardancy of PS/a-MMT composites was studied. In the case of a-MMTs from spraying drying, a good protective layer with foam-like aggregate state of MMT sheet was formed in the residue, which results in low peak value of heat release rate of PS/a-MMT composites.

Studies of silicon-containing maleimide polymers. Part II: Synthesis and properties of poly(styrene-co-brominecontaining maleimide).

AbstractSoluble copolymers of a series of bromine-containing (N-maleimido phenoxy) silane (BMS) monomers with styrene (St) were synthesized by radical polymerization in toluene using 2,2’-azobisisobutyronitrile (AIBN) as initiator. The comonomer reactivity ratios were calculated by the conventional Fineman-Ross and Kelen-Tüdos methods and a nonlinear least-squares Tidwell-Mortimer method. The glass transition temperatures (Tg’s) and thermal degradation of copolymers were determined by differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA) respectively. The introduction of silane side-chain into maleimide (MI) monomers changed the comonomer reactivity ratio with styrene from alternating to azeotropic copolymerization. The curves of Tg’s versus the different compositions of the above synthesized St-BMS copolymers matched a modified Tg’s equation as a increase in the effect of weight ratio on alternating-segment, and an S-shaped curve of deviation in comparison with the Fox’s equation. The MIsegments within these copolymers exhibited a good compatibility and, the flame retardancy of polystyrene could be enhanced via the introduction of Si/Brcontaining maleimide.

Studies of novel copolymers for deep‐UV photoresists. I. Synthesis and properties of poly(styrene‐co‐silicon‐containing maleimide)

AbstractSoluble copolymers of a series of (N‐maleimido phenoxy) silane monomers with styrene (St) were synthesized by radical polymerization in toluene using 2,2′‐azobisisobutyronitrile as initiator. The comonomer reactivity ratios were calculated by the conventional Fineman–Ross and Kelen–Tüdos methods and a nonlinear least‐squares Tidwell–Mortimer method. The glass transition temperatures (Tg's) and thermal degradation of copolymers were determined by differential scanning calorimetric and thermogravimetric analysis methods respectively. The introduction of silane side‐chain into maleimide (MI) monomers changed the comonomer reactivity ratio with styrene from an alternating to azeotropic copolymerization. The curves of Tg's versus the different compositions of the synthesized St‐MI copolymers (mentioned earlier) matched a modified Johnston's equation as increasing the effect of weight ratio on alternating segment, and exhibited an S‐shaped curve of deviation in comparison with the Fox's equation. The MI segments within these copolymers exhibited a good compatibility, and the thermal stability and flame retardancy of polystyrene could be enhanced simultaneously via the introduction of silicon‐containing MI. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3369–3375, 2006