Microcombustion Calorimetry Research Articles

Synergistic flame retardancy of poly(cyclotriphosphazene-co-piperazine) particle with aluminum diethylphosphinate in epoxy resin

Hexachlorocyclotriphosphazene (HCCP) was reacted with piperazine to obtain poly(cyclotriphosphazene-co-piperazine) particle (PCPS), which was used as the flame retardant for epoxy resin (EP). The structure of PCPS was determined by various methods. When PCPS was used alone and the addition amount of PCPS in the prepared flame-retardant EP (FR-EP) reached 4%, the obtained FR-EP cannot even pass the V-1 level in the Vertical burning (UL-94) test. However, PCPS showed a synergistic flame retardancy with aluminum diethylphosphinate (ADP). When the mixture of ADP and PCPS in EP was 4% and the weight ratio of ADP and PCPS was 3:1, the prepared FR-EP, EP-ADP/PCPS3:1, reached the V-0 level in the UL-94 test. The limiting oxygen index (LOI) value of EP-ADP/PCPS3:1 was 29.7%. Compared with pure EP, the peak heat release rate of EP-ADP/PCPS3:1 obtained by the micro-combustion calorimetry (MCC) test was reduced by 20.6%. Thermogravimetric analysis (TGA) result showed that, with the addition of ADP and PCPS, the char residual of EP-ADP/PCPS3:1 increased about 5.1% compared with EP. The combination of ADP and PCPS showed significant advantage in promoting the flame retardancy of EP. Compared with pure EP, the mechanical properties of EP-ADP/PCPS3:1 was hardly decreased with the addition of ADP and PCPS.

Developing highly flame-retardant PA6-based composites via in-situ PPS nanofiber network

This study investigates the enhancement of flame-retardant properties in polyamide 6 (PA6) composites through the incorporation of nanofibrillated polyphenylene sulfide (PPS) and a flame retardant, ammonium sulfamate (AS). By strategically combining a fibrillar PPS component (15 wt%) with a minimal AS concentration (1 wt%), the composite achieves a UL 94-V0 rating and a heightened limiting oxygen index (LOI) of 33.8 %. Rheological analyses reveal the formation of an entangled fibril network, contributing to a solid-like response that effectively suppresses flame propagation and prevents dripping. Micro-combustion calorimetry (MCC) results demonstrate a synergistic effect between the PPS nanofibril network and AS, leading to a significant 17 % reduction in peak heat release rate (PHRR) in PA6-nanofibrillated PPS-AS composites, showcasing improved flame-retardant properties compared to neat PA6. Despite a trade-off in mechanical properties, this research presents a promising strategy for enhancing the flame-retardant performance of PA6 composites, offering valuable insights for addressing fire safety challenges in PA6 applications.

Flame-retardant aramid felt-reinforced phenolic coatings for carbon fiber-reinforced polymers (CFRPs)

For over fifty years since carbon fiber-reinforced polymers (CFRPs) were introduced to the automotive industry, enhancing their flame-retardant properties has been studied due to their vulnerability to fire. Coating is one method of flame-retardant enhancement, accomplished by modifying surface characteristic to achieve its goal. Phenolic resin-based coatings, as a candidate material, offer advantages such as good chemical compatibility and cost efficiency. However, to meet the necessary specifications for flame-retardant performance, a thick coating layer with higher brittleness is required. In this study, we developed an aramid felt-reinforced coating layer to address the limitations of phenolic coatings. The effectiveness of the flame-retardant coating was demonstrated through various tests, including limiting oxygen index (LOI), micro-combustion calorimetry, heat exposure test with cone shaped heater, and mechanical property tests including surface-burning test. Consequently, the aramid felt-reinforced phenolic coating exhibited superior flame-retardant enhancement using a cost-effective, easy-to-follow, and lightweight method, achieved with a relatively thin coating fabrication.

Preparation, Cure, Characterization, and Mechanical Properties of Reactive Flame-Retardant Cyanate Ester/Epoxy Resin Blends and their Carbon Fiber Reinforced Composites

This study explores the formulation space of flame retardant thermoset polymers, specifically involving blends of epoxy and cyanate ester (EP/CE) and a reactive phosphorus-based flame retardant, poly (m-phenylene methylphosphonate) (PMP). Two CE monomers were investigated, each blended with the same epoxy monomer (DGEBA) in a 1:1 wt ratio. The impact of phosphorus concentration on the neat (neat meaning no fibers were present) resin blends was characterized using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The flammability and mechanical characteristics were assessed using micro-combustion calorimetry (MCC) and dynamic mechanical analysis (DMA). Carbon fiber composite panels were successfully fabricated using a wet layup process and autoclave curing with a fiber volume fraction (Vf) of approximately 0.5. DMA testing of the cured composite laminates pinpointed that the average Tg of the EP/CE blend was reduced with PMP addition by up to 39 °C at a phosphorous level of 3 wt%. Cone calorimetry tests confirmed the effectiveness of the flame retardant by reducing the peak Heat Release Rate (HRR) by approximately 27 %. The integration of PMP into EP/CE only marginally reduced the 3-point flexural strength (6–15 %) and modulus (7–13 %) relative to baseline samples.

Flame retardancy and mechanical properties of epoxy resin with the phytic acid‐derived flame retardant

AbstractThe synthesis and application of the bio‐derived flame retardant can meet the current requirements for the high‐efficient and sustainable development of flame retardants. Therefore, using phytic acid (PA), 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO), and piperazine as raw materials, a PA‐derived flame retardant (PAPDOPO) was prepared. Fourier transform infrared spectroscopy and x‐ray diffraction techniques were applied to characterize the structure of the PAPDOPO. In the prepared flame‐retardant epoxy resin (FEP), PAPDOPO showed high flame retardancy. When 4% PAPDOPO was added into epoxy resin (EP), the prepared FEP (EP‐PAPD‐4) passed the V‐0 level in the UL‐94 test, and the limited oxygen index value of EP‐PAPD‐4 reached 35.3%. Microcombustion calorimetry test was also applied to demonstrate the performance of PAPDOPO. The peak heat release rate of EP‐PAPD‐4 was reduced by 30.4% compared with that of the pure EP. Due to the low addition amount of PAPDOPO in FEP, the mechanical properties of the FEP using PAPDOPO as flame retardant were hardly decreased compared with pure EP.

Intrinsically Noncombustible Thermosets from Sulfur-Containing Epoxy Resin and Benzoxazines: Evaluation of Thermal and Mechanical Properties

Benzoxazine (BZ)-epoxy copolymers exhibit favorable mechanical properties, but their thermal and flame-retardant characteristics are impaired at high epoxy fractions. Here, we report a new type of sulfur-containing epoxy resin (EPS), which we synthesized using 4,4’-thiobisphenol (TBP) instead of bisphenol A (BA) and then blended with three sulfur-containing BZs (TBP-a, TBP-fa, and TBP-tma). The polymerization behavior of the resins was analyzed using Fourier transform infrared spectroscopy and differential scanning calorimetry for determining the optimal curing procedure. This analysis revealed that the oxazine and epoxy rings undergo ring-opening and cross-linking reactions at the same time and that double-substituted structures originating from the furan and thiophene rings appeared during the curing process. Thermogravimetric analysis showed that the addition of EPS increased the initial decomposition temperature by hindering the formation of double-substituted structures. The char yield at 800°C decreased owing to the unstable C–O–C–C–O groups derived from the ring-opening of EPS. To prepare the self-extinguishing copolymers with a char yield of 24%, a smaller quantity of BZ was needed for the EPS-based blends than for the BA-based ones. The heat release capacities—measured using micro-combustion calorimetry—of all copolymers except TBP-a/EPS were less than 300 J/g·K, demonstrating that the presence of thioether bonds and double-substituted structures resulted in excellent flame retardancy. The TBP-fa/EPS copolymer also exhibited excellent flame retardancy in cone calorimeter measurement. Finally, the glass transition temperature of the TBP-fa/EPS copolymer at a ratio of 5 : 5 (w/w) reached as high as 289°C. A TBP-fa/EPS copolymer with an epoxy content of 70% had nearly the same storage modulus (2,206 MPa) at 50°C as poly(BA-a) and thus similar mechanical properties. In summary, BZ-epoxy copolymers prepared from sulfur-containing epoxy combine the advantages of the constituent components and extend their areas of application.

Thermoplastic polyurethane composite modified by piperazine pyrophosphate: Flame retardancy, thermal stability and combustion properties

In this work, flame retarded thermoplastic polyurethane (TPU) composites were fabricated by introducing a novel flame retardant piperazine pyrophosphate. The flame retardany, thermal stability and combustion performance were systematically investigated. Flame retardant tests confirmed that thermoplastic polyurethane/piperazine pyrophosphate (TPU/PAPP) composites showed LOI of 27.5 vol% without any melt dripping when only 5 wt% PAPP was added. micro-combustion calorimetry (MCC) test implied that PAPP significantly suppressed heat release of TPU/PAPP composites. 10 wt% of PAPP endow PHRR1 and THR values TPU/PAPP10 decreased by 67.0% and 35.1% compared with TPU. Thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR) showed that PAPP significantly inhibited the release of toxic and combustible gases. The char residue investigation showed that TPU/PAPP composites formed compact char residue, which was able to effectively inhibit the heat and mass transmission in combustion. Based on the investigation, the work mechanism of PAPP in TPU/PAPP composites was proposed.

Simultaneous enhancement of mechanical strength and flame retardancy of lyocell fiber via filling fire-resistant cellulose-based derivative

Functional materials such as fireproof fabrics or fibers usually destroy mechanical strength due to the introduction of flame retardant. In this work, ionic liquid 1,3-dimethyl imidazolium methyl phosphite, one solvent and modifier, was employed to fabricate phosphorylated cellulose. As a cellulose-based derivative, phosphorylated cellulose displayed good compatibility and dispersity in cellulose spinning which was proved by the uniform cellulose spinning dope and compact fiber structure. Owing to the special and similar structure, phosphorylated cellulose interaction with cellulose unit was conducive to enhancing mechanical strength of lyocell fiber. The flame retardant lyocell fibers (FRLF) with phosphorus content (<1 at %) exhibited excellent flame retardancy. The value of peak of heat release rate (PHRR) declined by 50.9 % compared with pure lyocell fibers (LF), as micro-combustion calorimetry measurement estimated. Meanwhile, the breaking strength of FRLF increased by 6.44 % compared with that of LF. In brief, this work balanced the flame retardancy and mechanical properties of lyocell fibers via one-step synthesizing fire retardant cellulose-based filler based on the structural similarity between matrix and flame retardant.

Natural bioactive formulations for biodegradable cotton eco-fabrics with antimicrobial and fire-shielding properties

In this study, eco-friendly cotton fabrics with antimicrobial and flame-retardant properties were produced using newly developed bioactive formulations. The new natural formulations combine the biocidal properties of the biopolymer (chitosan (CS)) and essential oil (thyme oil) (EO) with the flame-retardant properties of mineral fillers (silica (SiO2), zinc oxide (ZnO), titanium dioxide (TiO2), and hydrotalcite (LDH)). The modified cotton eco-fabrics were analyzed in terms of morphology (optical and scanning electron microscopy (SEM)), color (spectrophotometric measurements), thermal stability (thermogravimetric analysis (TGA)), biodegradability, flammability (micro-combustion calorimetry (MCC)), and antimicrobial characteristics. The antimicrobial activity of the designed eco-fabrics was determined against different kinds of microorganism (S. aureus, E. coli, P. fluorescens, B. subtilis, A. niger, C. albicans). The antibacterial effects and flammability of the materials were found to depend strongly on the compositions of the bioactive formulation. The best results were obtained for the samples of fabric coated with the formulations containing LDH and TiO2 filler. These samples showed the highest decreases in flammability, with heat release rate (HRR) values of 168 (W/g) and 139 (W/g), respectively, compared to the reference (233 W/g). The samples also showed very good inhibition of growth against of all the studied bacteria.

Phosphorus-Containing Flame-Retardant Benzocyclobutylene Composites with High Thermal Stability and Low CTE.

As a component of printed circuit substrate, copper clad laminate (CCL) needs to meet the performance requirements of heat resistance, flame retardancy, and low coefficient of thermal expansion (CTE), which, respectively, affects the stability, safety, and processability of terminal electronic products. In this paper, benzocyclobutylene (BCB)-functionalized phosphorus-oxygen flame retardant composites were prepared through introducing the BCB groups, and the performance was researched by thermogravimetric analysis, microcombustion calorimetry, and thermomechanical analysis. The research results show that these phosphorus oxide compounds containing BCB groups show good thermal stability and low total heat release (THR) after thermal curing, and the more BCB groups on the phosphorus oxide monomers, the better the thermal stability and flame retardancy of cured resins. The Td5 and THR of the composite (M3) are as high as 443 °C and 23.1 kJ/g, respectively. In addition, the CTE of M3 is as low as 16.71 ppm/°C. Introduction of BCB groups which can be crosslinked through heat to improve the thermal stability, flame retardancy, and reduced CTE of traditional organophosphorus flame retardant materials. These materials are expected to be good candidates for CCL substrates for electronic circuits.

Preparation of a copper porphyrin derivative and its surface modification for simultaneously endowing PET fibers with dyeing, flame retardant and anti-dripping performance

Polyethylene terephthalate (PET) fibers are the most numerous synthetic fibers in the world, but their flammability and high-temperature melt dripping limit their further applications. To address these issues, a copper porphyrin derivative, i.e., copper 2‑methoxy-4-(10,15,20-tris(4-((diphenylphosphoryl)oxy)-3-methoxyphenyl) porphyrin-5-yl) phenyl diphenylphosphinate (MTPD-Cu) was firstly synthesized from biomass vanillin in this paper. Then, MTPD-Cu was used for the surface modification of PET fibers via the dyeing process to prepare multifunctional PET fibers (FR-PET) with dyeing, flame retardant and anti-dripping properties. The flame retardancy, thermal stability, anti-dripping and color fastness of FR-PET were evaluated by limiting oxygen index (LOI), burning test, micro combustion calorimetry (MCC), thermogravimetric analyzer (TGA), and water washing color fastness test. The results revealed that the LOI value increased from 21% for pure PET fibers to 29.8% for FR-PET fibers. Meanwhile, compared to pure PET fibers, the total heat release (THR) and peak heat release rate (PHRR) of FR-PET decreased by 79.8% and 57.8%, respectively. The residual char of FR-PET was significantly improved whether in nitrogen or in air atmosphere at 800 °C, showing good char forming ability. In addition, FR-PET exhibited no melt dripping phenomenon and was pink with excellent color fastness to washing. Furthermore, the possible flame retardant and anti-dripping mechanisms were also proposed. This work provides a simple and easy modification method to simultaneously endow PET fibers with dyeing, flame retardancy and antibacterial properties, which is easy to be prepared on a large scale.

Ion – complexed chitosan formulations as effective fire-retardant coatings for wood substrates

In the present work, two chitosan based formulations – intended to be used as flame retardant coatings - were prepared by ionic crosslinking of hypophosphorous acid-modified chitosan with either nitrilotris(methylenephosphonic acid) (NTMP) or phytic acid (PA). Thermal properties and flammability of the two ion – complexed chitosan formulations were subsequently investigated through thermogravimetric analysis (TGA), microcombustion calorimetry (MCC), and cone calorimeter (CC). As a case study, the two formulations were used to coat wood specimens. Coated samples with both NTMP and PA crosslinked chitosan showed an increase in char residue compared to pristine wood and self-extinguishing behavior in horizontal configuration. The most significant reduction in flammability was found in NTMP crosslinked chitosan coating, being capable of (i) extinguishing the flame in vertical configuration; (ii) preventing ignition under a 50 kW/m2 heat flux and (iii) reducing both total heat release rate (THR) and peak heat release rate (pHRR) by over 96% compared to the uncoated control during CC experiments. Furthermore, we demonstrated good compatibility with an epoxy-based, waterproofing top coat in order to preserve crosslinked chitosan coatings. Durability and propensity for fungal growth of the coatings were also assessed. As follows, this newly developed ionic crosslinked chitosan coating has considerable potential for applications in renewable intumescent flame retardant systems.

A Vanillin-Derived, DOPO-Contained Bisphenol as a Reactive Flame Retardant for High-Performance Epoxy Thermosets

Quest for bio-based halogen-free green flame retardant has attracted many concerns in recent years. Herein a reactive functional flame retardant containing phosphorus VDP is synthesized from vanillin, 9,10-dihydro-9-oxa-10-phosphophene-10-oxide (DOPO) and phenol via a facile way. VDP is characterized with 1H NMR, 31P NMR, FTIR and Time of Flight Mass Spectrometry, and used as a new reactive flame retardant for bisphenol epoxy thermosets. Thermogravimetry analysis shows that when the VDP loading is only 0.5P% (based on phosphorus content), the residue increases from 14.2% to 21.1% at 750°C in N2 compare with neat DGEBA. Correspondingly, the limit oxygen index increased to 29.6%, and flame retardancy reaches UL-94 V0 grade. Micro combustion calorimetry (MCC) and cone calorimetry analyses demonstrate that VDP can significantly lower flammability of the epoxy thermoset. With only 0.5P% of VDP, the heat release rate, total heat release rate and smoke production are reduced markedly. At the same time, the mechanical properties of the modified epoxy thermosets are also improved. The impact strength increases by 34% and the flexural strength increased by 23%, with 1.5P% of VDP. In short, VDP not only improves the flame retardancy, but also improves the mechanical properties of the epoxy thermosets.

Flame retardancy of polyurethane foams prepared from green polyols with flame retardants

AbstractPolyurethane foams (PUFs) were synthesized using bis(2‐hydroxyethylene terephthalate) (BHET), 1,4‐cyclohexanedimethanol (CHDM), and polycaprolactone diol (PCLD), and their flame retardancies were investigated. BHET and CHDM are eco‐friendly chemicals derived from waste polyethylene terephthalate, and PCLD is a precursor monomer used for synthesizing biodegradable polymers. Expandable graphite (EG) and tris(1‐chloro‐2‐isopropyl) phosphate (TCPP) were used as flame retardants. For conventional PUFs prepared with an aliphatic polyol, thermal stability was significantly enhanced with EG and TCPP through thermogravimetric analysis (TGA) and micro‐combustion calorimetry (MCC). PUFs prepared with BHET and CHDM exhibited higher thermal stability than conventional PUFs. This is attributed to the alicyclic and aromatic ring structures, which contribute to thermally stable char formation during pyrolysis. PCLD was introduced as an additional polyol, as well as a possible flame retardant, without the addition of EG and TCPP. PUFs were successfully prepared and exhibited improved resilience to burning up to 300°C due to the intrinsic thermal stability of PCLD. The limiting oxygen index (LOI) indicated that PUFs containing BHET moiety exhibited higher LOI values, whereas PUFs prepared with PCLD showed the lowest LOI value. PCLD can be used as a polyol; however, additional flame retardants are needed to obtain high flame retardancy for PUFs.

Flame retardancy of rigid polyurethane foams containing thermoregulating microcapsules with phosphazene-based monomers

Thermoregulating microcapsules (MC) with flame-retardant properties were used to produce polyurethane (PU) foams. Thermogravimetric analyses of the microcapsules performed under atmospheric air and nitrogen confirmed that the hexa(methacryloylethylenedioxy) cyclotriphosphazene (PNC-HEMA) monomer raised the amount of residue after exposure to high temperature, proving the formation of a thermally stable char layer. Additionally, the flame-retardant properties of the microcapsules were analyzed by micro-combustion calorimetry (MCC), and the PU foams were tested by both MCC and cone calorimetry. The total heat release and maximum heat release rate were lower for microcapsules containing the flame-retardant PNC-HEMA. The composition of the microcapsules has been proved by MCC and TGA, where the release of the encapsulated phase change material (PCM) occurred at the expected temperature. However, in PU foams, the release of PCM is shifted to higher temperatures. Accordingly, these materials can be considered as an important alternative to commonly used microcapsules containing phase PCMs, where a lower flammability is required for their future application.Graphic abstract

Application of Earth Pigments in Cycloolefin Copolymer: Protection against Combustion and Accelerated Aging in the Full Sunlight Spectrum.

In this paper, we assess various natural earth pigments as potential colorants and stabilizers for ethylene–norbornene copolymer composites. Several cycloolefin copolymer (COC) composites colored with 2 wt% of a selected pigment were prepared using a two-step mixing method. The aging resistance of the polymer composites was investigated in terms of changes to their mechanical properties, following accelerated aging in the full sunlight spectrum (100, 200, 300, 400, and 500 h). Fourier-transform infrared spectroscopy (FTIR), surface energy measurements, and spectrophotometry were used to assess the color changes, surface defects, and morphology of the composites. Thermogravimetric analysis (TGA) was used to study their thermal stability. The combustion characteristics of the prepared COC composites were evaluated based on the microcombustion calorimetry test (MCC). The application of earth pigments resulted in interesting color changes and a significant improvement in the aging resistance of the COC-filled samples, as evidenced by higher aging factor values and lower carbonyl index parameters compared to the reference (COC). The best results were observed for hematite (HM), gold ochre (GO), and red ochre (RO). In addition, the application of earth pigments, especially iron ochre (IO) and red ochre (RO), in COC contributed to a significant reduction in the heat release rate (HRR) values, indicating improved flame retardancy. This research opens the possibility of producing colorful COC composites with enhanced photostability and reduced flammability for use in polymer applications.

Highly Flexible Graphene Derivative Hybrid Film: An Outstanding Nonflammable Thermally Conductive yet Electrically Insulating Material for Efficient Thermal Management.

In modern society, advanced technology has facilitated the emergence of multifunctional appliances, particularly, portable electronic devices, which have been growing rapidly. Therefore, flexible thermally conductive materials with the combination of properties like outstanding thermal conductivity, excellent electrical insulation, mechanical flexibility, and strong flame retardancy, which could be used to efficiently dissipate heat generated from electronic components, are the demand of the day. In this study, graphite fluoride, a derivative of graphene, was exfoliated into graphene fluoride sheets (GFS) via the ball-milling process. Then, a suspension of graphene oxide (GO) and GFSs was vacuum-filtrated to obtain a mixed mass, and subsequently, the mixed mass was subjected to reduction under the action hydrogen iodide at low temperature to transform the GO to reduced graphene oxide (rGO). Finally, a highly flexible and thermally conductive 30-μm thick GFS@rGO hybrid film was prepared, which showed an exceptional in-plane thermal conductivity (212 W·m-1·K-1) and an excellent electrical insulating property (a volume resistivity of 1.1 × 1011 Ω·cm). The extraordinary in-plane thermal conductivity of the GFS@rGO hybrid films was attributed to the high intrinsic thermal conductivity of the filler components and the highly ordered filler alignment. Additionally, the GFS@rGO films showed a tolerance to bending cycles and high-temperature flame. The tensile strength and Young's modulus of the GFS@rGO films increased with increasing the rGO content and reached a tensile strength of 69.3 MPa and a Young's modulus of 10.2 GPa at 20 wt % rGO. An experiment of exposing the films to high-temperature flame demonstrated that the GFS@rGO films could efficiently prevent fire spreading. The microcombustion calorimetry results indicated that the GFS@rGO had significantly lower heat release rate (HRR) compared to the GO film. The peak HRR of GFS@rGO10 was only 21 W·g-1 at 323 °C, while that of GO was 198 W·g-1 at 159 °C.

Quantification of microplastics in a freshwater suspended organic matter using different thermoanalytical methods – outcome of an interlaboratory comparison

A sedimented freshwater suspended organic matter fortified with particles of polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET) was employed in an interlaboratory comparison of thermoanalytical methods for microplastics identification and quantification. Three laboratories performed pyrolysis gas chromatography-mass spectrometry (Py-GC-MS), three others provided results using thermal extraction desorption followed by gas chromatography coupled to mass spectrometry (TED-GC-MS). One participant performed thermogravimetry-infrared spectroscopy (TGA-FTIR) and two participants used thermogravimetry coupled to mass spectrometry (TGA-MS). Further participants used differential scanning microscopy (DSC), a procedure based on micro combustion calorimetry (MCC) and a procedure based on elemental analysis. Each participant employed a different combination of sample treatment, calibration and instrumental settings for polymer identification and quantification. Though there is obviously room for improvements regarding the between-laboratory reproducibility and the harmonization of procedures it was seen that the participants performing Py-GC-MS, TED-GC-MS, and TGA-FTIR were able to correctly identify all polymers and to report reasonable quantification results in the investigated concentration range (PE: 20.0 μg/mg, PP: 5.70 μg/mg; PS: 2.20 μg/mg, PET: 18.0 μg/mg). Although for the other methods limitations exists regarding the detection of specific polymers, they showed potential as alternative approaches for polymer quantification in solid environmental matrices.

Intumescent polydopamine coatings for fire protection

Polydopamine with additional bioderived flame retardants was used as coatings for flexible polyurethane foam and triple-wall corrugated cardboard. Clay was used to prevent the foam from collapsing during combustion. Dopamine can also effectively intercalate clay to produce well-distributed coatings, so it was used in all coatings. Scanning electron microscopy was used to examine the morphology of the coatings. The amount of polydopamine coating applied to clay platelets and the morphology of the aggregates formed were greatly affected by the catalyzing base used. Amine-containing bases produced the largest aggregates and gaseous ammonia was found to be an effective base. The ability to form intumescing coatings was crucial for achieving good flame protection. Microcombustion calorimetry, flame-spread and cone calorimetry experiments revealed that (aminomethyl)phosphonic acid and glycine phytate produce intumescing chars that, in combination with montmorillonite clays, form a protective barrier for both foam and cardboard. The added flame retardants were also important for reducing the smoldering propensity of cardboard after flame extinguishment.

Effects of Carbon Nanotube-Phosphorus Based Flame Retardant Combinations on Flammability of Polypropylene

The effects of multi-walled carbon nanotubes (MWCNTs) on fire behavior of phosphorus-based flame retardant (PBFR)/polypropylene (PP) were investigated. Two different type phosphorus-based flame retardant that commercially available; ammonium polyphosphate-based (Exolit AP 760) and organic phosphorous-based (Aflammit PCO 900) powders were studied to enhance the flammability of polypropylene. Phosphorus-based flame retardant content was fixed at 8 wt% of total flame retardant (FR) formulation. MWCNTs was incorporated into FR formulation at four different concentrations (0.5 wt%, 1.0 wt%, 1.5 wt% and 2.0 wt%). All composites were prepared by melt compounding in a twin-screw extruder followed by injection molding technique. Thermal properties and flammability of the prepared samples were determined by thermogravimetric analysis (TGA), limiting oxygen index (LOI) and micro combustion calorimetry (MCC). Incorporation of organic phosphorous-based powder into PP matrix showed a better fire performance compared to ammonium polyphosphate-based flame retardant by resulting in an 11.6% higher LOI value. The LOI values decreased with the incorporation of MWCNTs into PP/ PBFR combinations; however, they still increased the thermal stability of each respective system. The addition of 2.0 wt% MWCNTs decreased the LOI value of PP/organic phosphorous-based FR system 5.2% higher than PP/ammonium polyphosphate-based FR system. The heat release rate of PP reduced in the presence of both PBFRs, but; increased with the introduction of MWCNTs