Papers by Keyword: Flame Retardancy

Abstract: The sepiolite and Al₂O₃-doped sepiolite contents in the as-received sepiolite/epoxy systems were maintained at 2 and 4wt %, respectively. The flame-retardant capabilities and combustion behavior of Al₂O₃-doped sepiolite in epoxy resin were meticulously evaluated through a series of tests including cone calorimetry (CC), limiting oxygen index (LOI), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). Several features, including degradation kinetics, combustion characteristics, thermomechanical properties, flame retardancy, and thermal degradation were evaluated with the intention of drawing comparisons to standard sepiolite. The findings from the studies were positive. In contrast, Al₂O₃-doped sepiolite not only further improved the LOI values and char formation post-cone testing but also decreased the previously mentioned combustion-related parameters in the composites. A potential synergistic interaction between sepiolite and Al₂O₃ in augmenting the flame retardancy of the composite was suggested. The thermal degradation of composites was only little affected by addition of sepiolite, although Al₂O₃-doped sepiolite addition seemed to speed up the deterioration process. The epoxy composite’s glass transition temperature (Tg) was shown to increase when sepiolite or Al₂O₃-doped sepiolite was added, as determined by DMA. The findings presented in this research provided a practical approach to improving the fireproofing of polymers. Keywords: Al2O3-doped sepiolite; TGA, flame retardancy; DSC, epoxy; thermal properties.

Abstract: In this paper, the sol-gel technique was used to design hybrid phosphorus-doped silica structures for improving the thermal stability and flame retardancy of cotton fabrics. To this aim, diethylphosphatoethyltriethoxysilane (DPTS) was employed as phosphate alkoxysilane in a multistep procedure that involved multiple layers (from 1 to 6) depositions. The multi-layer coatings were applied by padding using sols containing appropriate molar ratios of the precursor, anhydrous ethanol, catalyst, and hydrochloric acid. Moreover, the synergism P-N on flame retardancy of cotton was assessed by introducing 3-aminopropyltriethoxysilane (APTES) as an N-donor precursor in DPTS sols. The effects of the catalyst during the alkoxide reaction and the silica amount applied by sol-gel treatment on the thermo-oxidative behavior of the treated fabrics were deeply studied. The creation of the silica skeleton on the cotton surface and the interactions between the cellulosic fibres and the doped layer were investigated using FT-IR ATR spectroscopy. Moreover, thermal and thermo-oxidative stability, flammability properties, and combustion behavior of the sol-gel treated cotton fabrics were also studied, proving the effectiveness of the sol-gel coating in the fire protection of the cellulosic substrate.

Abstract: Epoxy resin (EP) mortar usually used to repair the cracking of concrete structure under damp environment, but EP is extremely flammable, thus it’s extremely imperative to design a novel multifunction EP grouting materials with flame retardancy and waterproofness for the practical application. Targeting ingenious decoration of EP grouting materials, multiple flame retardant elements (phosphorus, nitrogen and fluorine) are concurrently introduced into a fire retardant and the fire retardant defined as DDM-FNP. The obtained DDM-FNP/EP grouting composite possess high thermal stability, flame retardancy and hydrophobicity. The limiting oxygen index (LOI) value of DDM-FNP/EP composites has a significant improve, which is increased from 26.7 (EP-0) to 35.8 (EP-4). Composites with more than 10 wt% of DDM-FNP could pass UL-94 V-0 rating without dripping. Compared with EP-0, the PHRR and THR of EP-4 are decreased by 31.1% and 21.6%, respectively. In addition, due to the introduction of the F element, the water contact angle of EP composites is changed from 75.2° (hydrophilicity) to 98.6° (hydrophobicity) after the introduction of a certain amount of DDM-FNP flame retardant. Therefore, this work provide a new perspective to design a multifunction EP grouting composite and improve the value of practical application on seepage prevention of tunnel.

Abstract: In our previous work, ammonium polyphosphate (APP) microcapsule with the shell of boron modified phenolic resin (BPF) was prepared, recorded as BPFAPP. However, the compatibility and the flame retardancy of BPFAPP in thermoplastic polyurethane elastomer (TPU) are still not very good due to the brittle and hard shell wall. To improve the brittleness of microcapsules shell and the property reinforcements of APP in TPU, APP was encapsulated with the tung oil and boron modified phenolic resin (TBPF) in this paper, recorded as TBPFAPP. The property reinforcements of TBPFAPP in TPU were studied. The thermogravimetry, limiting oxygen index and cone calorimetry analysis showed that TPU/TBPFAPP composite had higher char yield and better flame resistance. The tensile strength and elongation at break showed that the mechanical properties were also significantly improved due to the introduction of α-Eleostearate.

Abstract: Polyamide 66 (PA66) benefits from excellent mechanical properties and good chemical resistance, which enabled wide application of this material in various industrial fields; however, it suffers from high flammability. Generally, preparation of a flame retardant PA from a reactive flame retardant involves a two-step process. In this study, the flame retardant PA66s (FRPA66s) are synthesized via a one-pot melt copolycondensation route by using a reactive phosphorus-containing flame retardant (FR-B). Then, molecular weight, some mechanical and thermal properties along with flame retardant properties of FRPA66s were investigated by gel permeation chromatography (GPC), instron material testing, differential scanning calorimetry (DSC), thermogravimetry (TG) analysis, vertical burning test (UL 94), and limiting oxygen index test (LOI) techniques. The experimental results confirmed that FRPA66s synthesized by the one-pot method have very similar properties compared to those obtained via the two-step process. Moreover, the prepared materials showed good non-flammability behavior with limiting oxygen index value of over 30% and a vertical burning test result of V-0 rating.

Abstract: The effects of carboxylic functionalized multi-walled carbon nanotubes (CNT) contents on electrical and flammability properties of poly(lactic) acid/CNT nanocomposites were investigated. The PLA/CNT nanocomposites were prepared by melt-blending method, where the CNT contents were varied from 1 to 9 phr. From flammability properties analysis, nanocomposites with 9 phr CNT showed the highest limiting oxygen index (LOI) of 26.5 vol% as compared to 19.5 vol% of neat PLA. All nanocomposites with higher than 5 phr CNT contents also passed the V0 class of UL-94 vertical burning test rating. The direct current electrical test revealed that the electrical conductivity increases by approximately seven orders of magnitude from 2.19 × 10^-11 S/m of neat PLA to 2.00 × 10^-4 S/m for PLA/CNT nanocomposites with 5 phr CNT contents. The electrical conductivity of PLA/CNT continues to increase beyond 5 phr contents, with 2.26 × 10^-3 S/m and 4.29 × 10^-3 S/m respectively for 7 and 9 phr contents. The good dispersion of CNT leads to formation of electron conducting CNT networks throughout the insulating PLA matrix.

Abstract: Due to its wide application improvement of fire protection of materials has always been topical. Aim of the research is to render textile materials less flammable in an economically and environmentally friendly manner using modified commercial products. Plain wave cotton fabric pretreated with cyclic phosphonate flame retardant (FR) Itoflam PES was used in experiments. Printing pastes Printperfect LAC 60, Tubiscreen EX-TS and Printperfect EX-AR with additive antimony trioxide (Sb₂O₃) were used for additional treatment of cotton fabric via flat screen coating method. FR properties, physico – mechanical characteristics (tensile strength, elongation, stiffness, abrasion resistance) were examined. It is concluded that foamed coating increases the stiffness and abrasion resistance of material. Recommendations for material application are given.

Abstract: Three bis-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-phosphonamidates were successfully synthesized and well characterized. The influence of these DOPO-phosphonamidates on fire performance of epoxy resin was comparatively investigated. UL-94 tests results of various EP formulations indicated that DOPO-phosphonamidates exhibited superior fire performance. The EP composite containing extremely low loading of PiP-DOPO (0.5 wt% P) may pass the UL-94 V-0 rating, while EDA-DOPO and DDM-DOPO made the EP pass the V-1 rating. Thermal degradation results of the DOPO-phosphonamidate indicated the higher thermal stability with the initial degradation temperature over 340 °C under nitrogen. Moreover, only a very small residue was observed at 800 °C for DOPO-phosphonamidates and all EP formulations under air and nitrogen, indicating the limited condensed phase interaction. DDM-DOPO with richer aromatic structures presented the highest thermal stability and left more char residues. Large amount of gas products during the combustion of PiP-DOPO rapidly released in a short time, promoting flame inhibition, which may explain its superior flame retardant efficacy among all the DOPO-phosphonamidates investigated in this study.