Skeletally Modified Polyamide Flame Retardant Coatings (original) (raw)
Related papers
Study on Thermal and Flame Retardant Properties of Phosphorus-containing Polyimides
Revista de Chimie
The present study aimed to design macromolecular architectures having imide core in the main chain and bearing two 9,10-dihydro-oxa-10-phosphaphenanthrene-10-oxide heterocycles in the side chain of each structural units as a synergetic two components key factor to induce attractive flame retardant properties in the resulted materials. The synthesis pathway consisted in the classical polycondensation reaction strategy using a phosphorus-containing diamine synthesized in the laboratory and three commercial dianhydrides co-monomers. The chemical structure confirmation of the phosphorus-containing polyimides has been performed by means of FTIR and NMR spectroscopy. The thermal stability of the products was introspected through TGA analysis. The char yields measured at 900oC ranged between 35% and 54%. Using these parameters limiting oxygen index values were theoretically calculated. Also, the microscale combustion calorimetry measurements have been conducted, in order to investigate the...
Developing flame retardant solutions for partially aromatic polyamide with phosphine oxides
Materials & Design, 2024
Partially aromatic polyamides owing to their excellent thermal stability are widely used in high temperature applications, however, like their aliphatic counterparts, they are readily flammable and more challenging to process. In this work, several organophosphorus flame retardants were synthesized and compounded with partially aromatic polyamide and evaluated for their processability, thermal, and fire behaviour. The compounds containing a commercial flame retardant, Exolit® OP 1230 (EX), and two new flame retardants, namely 1,4-phenylenebis(diphenylphosphine oxide) (MP) and (1,1′-biphenyl]-4,4′-diylbis(diphenylphosphine oxide) (BP), showed self-extinguishing capability (i.e., UL94 V0 class) with 4 wt% phosphorus (P) loading, together with a substantial reduction in the pHRR (up to 47 %), with respect to the pristine PAP. Rheological measurements on extended timescales were used to assess the melt stability of partially aromatic polyamide compounds. The presence of MP and BP in the polymer matrix did not trigger any excessive degradation phenomena such as chain scission, branching, or crosslinking reactions, thus, allowing a stable processability similar to a pristine partially aromatic polyamide sample. Finally, analysis of evolved gases during thermal decomposition revealed that MP and BP mainly exert a flame inhibition effect quite early in the decomposition process.
Industrial Crops & Products, 2023
The demand for "green" materials increases due to concerns about the effects of flame-retardant textiles. Using natural plant-base compounds such as phytic acid (PA) and the most abundant green amino polysaccharide chitosan (CS) as effective and durable flame retardants for textiles is essential for creating sustainable and ecological textile products. This study aims to develop a novel, eco-friendly, phosphorus-and nitrogencontaining flame retardant known as ammonium phytate (AP), intending to improve the flame retardant properties of polyamide 6.6 (PA6.6) textiles. UV-induced grafting with 2-acrylamide-2-methylpropane sulfonic acid (AMPS) increases the surface functional groups of PA6.6 fabrics. Later, the surface-modified fabrics were coated with phosphorus-containing heteroatom-based components, namely, sulfur, nitrogen, silicon, and boron, onto a single flame retardant system via layer-by-layer (LBL) deposition of positively charged chitosan/boron drop (3-aminopropyl) triethoxysilane/silicon dioxide (CS/BAPTES/SiO 2) sole solution and negatively charged AP solution to enhance superior hydrophilic and durable flame retardant performance. According to the data, a weight pickup of 56.5% is attributable to only 4 BLs. However, all the flame-retardant-coated fabrics can completely stop the melting-dripping tendency and achieve B-3 to B-2 ratings after the UL-94 vertical burning test. In addition, the LOI values of treated fabrics increase from 18.5% to 23.5% compared to a pure sample. The AMPS grafted with a 4BL-deposited fabric sample exhibits a maximum decrease in peak heat release rate (PHRR) of more than 54%. Moreover, the thermogravimetric analysis (TGA) test reveals a significant increase in thermal stability and char yield. Additionally, the as-prepared phosphorus-containing heteroatom-based coatings impart a water contact angle value of approximately 0⁰ within 2 s, demonstrating that the treated fabrics exhibit superior hydrophilic performance. Moreover, using AMPS-grafted and only 2-BL-deposited treatments improves coating stability in washing and imparts durable flame retardancy that can resist up to 20 washing cycles. It is proposed that the sustainable phosphorus-containing heteroatom-based coating may be a potentially effective replacement for existing durable flame retardants routinely used in textile finishing operations.
Die Angewandte Makromolekulare Chemie, 1999
The combustion performance of polyamide 6 (PA 6) and poly(butylene terephthalate) (PBT), both fire retarded by phosphorus oxynitride (PON), was studied by oxygen index (OI) and Underwriters Laboratory UL94 tests. It was shown that either PON alone or in combination with different co-additives is efficient in PA 6 and much less active in PBT. Thermogravimetric experiments provided evidence that PON promotes charring in both PA 6 and PBT. The mechanism of the char formation from PA 6 and PBT in the presence of PON was discussed on the basis of IR studies of solid residues produced in the thermal decomposition. The effective fire retardant action of PON in PA 6 is related to the interaction with the polymer to produce char, whereas the less effective activity of PON in PBT is related to the unfavorable acceleration of the evolution of combustible aliphatic fragments.
Fire Safety Journal, 2014
Glass-fiber reinforced polyamide 66 is flame retarded with a mixture of melamine-poly(zinc phosphate), (Safire s 400) and diethyl aluminium phosphinate. The performance of this synergistic combination of additives is multi-modal and a comprehensive investigation is undertaken to elucidate the underlying flame retardancy mechanism. The strategy was to characterize the different chemical species responsible for flame retardancy that are generated in gas and condensed phases under different fire scenarios. Following heat release rate (HRR) curve of flame retarded polyamide formulations obtained by mass loss calorimeter, samples in different stages of degradation are collected and investigated. Further flame retardants and formulations were degraded in tubular furnace whose temperature protocol relied on thermal degradation profile obtained from thermogravimetric analysis (TGA). In either case, species generated in condensed phase were studied by solid state nuclear magnetic resonance spectroscopy (magic angle spinning (MAS) NMR; 27 Al, 31 P and 13 C), Fourier transform Infra-red spectroscopy (FTIR), X-ray powder diffraction (XRD), electron probe microanalysis (EPMA), scanning electron microscopy (SEM), and optical microscopy, whereas TGA coupled FTIR, and pyrolysis gas chromatography mass spectrometry (Py/GC/MS) were utilised to investigate species released in gas phase. Flame retardancy mechanism is elaborated based on the identification of the chemical species in both gas and condensed phases and their specific contributing role.
Polymer Bulletin, 2019
The present study attempts the synthesis of a cyclic multifunctional flame-retardant (FR) moiety from o-phenylenediamine (OPDA) as the starting material. OPDA was reacted with phenylphosphonic dichloride and further with the 3-monochloro-1,2-propanediol to obtain the final product (FRPOL) which was then incorporated into epoxy and polyurethane coating systems. The structure of the synthesized molecule was confirmed using hydroxyl value, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The cured coating films were characterized for thermal, mechanical and flame-retardant properties. Thermogravimetric analysis and differential scanning calorimetry were used to carry out the thermal degradation studies and to know the glass transition temperatures (T g), respectively. The thermal and mechanical properties were excellent after the incorporation of the synthesized molecule into the coating systems. The limiting oxygen index (LOI) and UL-94 vertical burning tests were carried out to check the flame retardancy of the cured coating films. The polyurethane with FR had the maximum LOI value of 32 while the epoxy with 45% concentration of FR had a maximum LOI value of 26 among all the coating formulations. The formulations with FRPOL displayed selfextinguishing behavior with no dripping in UL-94 test.
Radiative heat transfer dominates in medium-to large-scale fires, with infrared ray absorption causing the rapid ignition of combustible materials. In an attempt to hinder this phenomenon, low-emissivity coatings consisting of an aluminum layer topped by alumina have been deposited on polypropylene (PP) and polyamide 6 (PA6) substrates by pulsed DC magnetron sputtering. Emissivity measurements have confirmed the decrease in the emissivity of both surfaces. The samples were tested with a mass loss cone (MLC) calorimeter at 50 kW/m 2 to mimic the radiative thermal constraint of the last stages of a developing fire. The evolution of the temperature was monitored by a thermocouple to confirm the radiative barrier effect. With this setup, it was evidenced that the presence of low-emissivity coatings reduced the heat absorption, effectively increasing the time to ignition of both substrates. Indeed, coated PP ignited after 7 min, whereas a neat PP ignited in 1 min, and PA6 had a time to ignition of as long as 1 h, as opposed to the neat polymer igniting in only 75 s. However, the effect of the coating on flammability parameters such as the peak heat release rate (PkHRR) and the total heat release (THR) was found to be very low. To counterbalance this downside and to take advantage of the reduction of heat absorption, Al/Al 2 O 3 coatings were deposited on PP and PA6 filled with thermally triggered fire-retardant additives, respectively, expandable graphite and a commercial mixture of melamine polyphosphate and aluminum diethylphosphate. Without surface treatment, the presence of the additives caused a shorter time to ignition, but a reduction in the PkHRR of ∼50%. The combination of the Al/Al 2 O 3 coating with flame retardants in the bulk led to both a long time to ignition and a reduction in the PkHRR and the THR under MLC testing.
Polymer Degradation and Stability
The development of new flame retardants is of ever increasing importance because of ecotoxicity concerns over existing systems and related regulatory pressures. From a range of low-toxicity, water-insoluble reagents, a total of 151 metal complexes were assessed for their potential to impart flame retardant behaviour in polymer matrices. These were successfully synthesised on a small scale and possible interactions were explored with a model engineering polymer, namely polyamide 6.6 (PA66). Powder mixtures of each complex with PA66 in a 1:3 mass ratio were analysed under air using TGA/DTA. Based on the stability of each at the typical processing temperature of 290 o C and its char forming potential (the final residue requirement at 580 o C being > 25%), selected mixtures were then analysed further using a differential mass loss technique. Metal complex/PA66 mixtures in which the differential residual mass at 470 o C was > 10% with respect to the theoretical value were considered to have a positive char forming interaction. Only eight of the metal complexes passed this last criterion including aluminium, tin (II) and zinc tungstates, three tin (II) phosphorus oxyanion complexes, iron (II) aluminate and iron (III) hypophosphite. These selected compounds were synthesised on a larger scale (c.a. 100 g), characterised and compounded into PA66 at 5 wt% for flammability assessment using LOI, UL94 and cone calorimetry. Of these, only aluminium tungstate and iron (II) aluminate showed some degree of FR behaviour with LOI values ≥ 23.0 vol% compared with PA66 (LOI = 22.9 vol%) and the former almost achieved a UL94 V-2 rating. However, while up to 32% reductions in total heat releases and up to 49% reduction in PHRR in cone calorimetric tests were observed for the metal complex/PA66 composites generally, those for Al2(WO4)3 were 6 and 29% respectively and for Fe(AlO2)2 were 18 and 45% respectively
Iron compounds in non-halogen flame-retardant polyamide systems
Polymer Degradation and Stability, 2003
An effective flame retardant system for polyamide 4,6 was found based on inorganic iron compounds with polyphenylene oxide and zinc borate. Iron compounds have been known as flame retardant synergists in halogen systems but their utility in non-halogen systems has been largely unrecognized. The iron compounds appear to improve char morphology. Polyphenylene oxide provides the char-forming component. Evidence was developed for a positive interaction between the polyphenylene oxide, the iron compound and zinc borate. Favorable results from more recent studies of iron compounds in non-halogen systems are also briefly reviewed. #
Materials, 2020
The fire behavior of polymers is examined primarily with the time-dependent heat release rate (HRR) measured with a cone calorimeter. The HRR is used to examine the fire behavior of materials with and without flame retardants, especially Polypropylene (PP-Copo) and Polyethylene (PE-LD). Polypropylene is stored for up to 99 days under normal conditions and the heat release rate shows especially changes about 100 s after irradiation with cone calorimeter, which may be caused by aging effects. The effect of crosslinking to the burning behavior of PP was examined too. Polyamides (PA 6) are irradiated with a radiation intensity of 25 kW/m2 to 95 kW/m2 and fire-related principles between radiation intensity and time to ignition can be derived from the measurement results. In order to comprehensively investigate the fire behavior of PP (also with flame retardant additives), the samples were also exposed to a flame, according to UL 94 with small power (50 W) and is inflamed with the power o...