Search

To alleviate the fire hazard of epoxy resin (EP), an efficient flame retardant (ADM) containing phosphophenanthrene and thiazole groups is synthesized and used as co-curing agent for 4,4′-diaminodiphenyl methane to prepare EP/ADM composites. EP/4 mass% ADM composites with phosphorus content of only 0.25 mass% reach UL-94 V-0 rating and the limiting oxygen index value is high to 35.8%. The results reveal that the peak heat release rate, total smoke production, and total heat release of EP/4 mass% ADM composites are reduced by 24%, 14.4% and 16.7%, respectively, in comparison with those of pure EP. The improvement in flame retardancy is mainly attributed to the decomposition of DOPO which produces HPO• and PO• to capture the reactive radicals in the gaseous phase. The thiazole group releases hindered amine groups and inactive gas with a dilution effect in the gaseous phase thus further enhancing the effect of the phosphophenanthrene group. Besides, ADM helps to increase the glass transition temperature (Tg) of EP/ADM composites, which is 176 °C for EP/4 mass% ADM composites, which is higher than the value (172 °C) of EP. [ABSTRACT FROM AUTHOR]

Epoxy resin (EP) has been widely used in coatings, adhesives, and composites. However, EP is flammable with severe smoke production. The addition of flame retardant fillers into EP can effectively improve its flame retardancy, but often brings mechanical reduction to EP. Herein, a high‐effective boron‐containing flame‐retardant (2‐phenyl‐1,3,2‐dioxaborolan‐4‐yl) methanamine ammonium polyphosphate (PBMA‐APP) is synthesized and introduced into EP to improve the fire resistance and the impact toughness. With the addition of 6% PBMA‐APP, the fire performance of EP is significantly improved. The Underwriters Laboratories‐94 rating is increased to V‐0, the total heat release and total smoke production (TSP) are reduced by 30% and 32%, respectively. It is proposed that the synergistic effect among B, N, and P in PBMA‐APP promoted the char formation of EP. The addition of 6% PBMA‐APP into EP causes little effect on tensile strength but increases the impact strength of EP to 11.2 kJ m−2. This work has proposed a possible strategy to develop a high‐efficient flame retardant for thermosetting resins. [ABSTRACT FROM AUTHOR]

One of the current challenges in the development of flame retardants is the preparation of an environmentally friendly multi-element synergistic flame retardant to improve the flame retardancy, mechanical performance, and thermal performance of composites. This study synthesized an organic flame retardant (APH) using (3-aminopropyl) triethoxysilane (KH-550), 1,4-phthalaadehyde, 1,5-diaminonaphthalene, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as raw materials, through the Kabachnik-Fields reaction. Adding APH to epoxy resin (EP) composites could greatly improve their flame retardancy. For instance, UL-94 with 4 wt% APH/EP reached the V-0 rating and had an LOI as high as 31.2%. Additionally, the peak heat release rate (PHRR), average heat release rate (AvHRR), total heat release (THR), and total smoke produced (TSP) of 4% APH/EP were 34.1%, 31.8%, 15.2%, and 38.4% lower than EP, respectively. The addition of APH improved the mechanical performance and thermal performance of the composites. After adding 1% APH, the impact strength increased by 15.0%, which was attributed to the good compatibility between APH and EP. The TG and DSC analyses revealed that the APH/EP composites that incorporated rigid naphthalene ring groups had higher glass transition temperatures (Tg) and a higher amount of char residue (C700). The pyrolysis products of APH/EP were systematically investigated, and the results revealed that flame retardancy of APH was realized by the condensed-phase mechanism. APH has good compatibility with EP, excellent thermal performance, enhanced mechanical performance and rational flame retardancy, and the combustion products of the as-prepared composites complied with the green and environmental protection standards which are also broadly applied in industry. [ABSTRACT FROM AUTHOR]

A unique mono-component intumescent flame retardant, named PPy-MAPP, of which melamine-coated ammonium polyphosphate (MAPP) was microencapsulated by polypyrrole (PPy), was synthesized and carefully characterized. The obtained PPy-MAPP was applied to epoxy resin (EP) for obtaining flame-retarded EP composites. The results show that PPy-MAPP imparts better flame retardancy and smoke suppression properties to EP compared to the same addition of MAPP. The EP composite with 15 wt% PPy-MAPP easily passes the UL94 V-0 rating and achieves an LOI value of 42.4%, accompanied by a 61.9% reduction in total heat release (THR) and a 73.9% reduction in total smoke production (TSP) when compared with pure EP. The char residue analysis shows that PPy-MAPP can promote a generation of more phosphorus-rich structures in the condensed phase that improve the integrity and intumescence of char against fire. The mechanical test indicates that PPy-MAPP has a less negative effect on the tensile strength and elastic modulus of epoxy resin due to the good compatibility between PPy-MAPP and the EP matrix, as supported by differential scanning calorimetry (DSC) analyses. In this paper, these attractive features of PPy-MAPP provide a new strategy to prepare satisfactory flame retardant and super flame retarding EP composites. [ABSTRACT FROM AUTHOR]

• Mn 3 CoO x was prepared to enhance the fire safety of epoxy resins (EP). • Mn 3 CoO x impressively reduced pHRR and pSPR by 47.5 % and 34.6 %, respectively. • Mn 3 CoO x can effectively catalyze the transformation of hazardous gases. • Recovery of Mn 3 CoO x to 90.0 % in EP composite. The development of metal oxide flame retardants that are easy to synthesize, efficient, and recyclable would be more beneficial to circular economy. In this work, a porous core-shell Mn 3 CoO x was developed to efficiently reduce heat, smoke as well as hazardous gas during the combustion of epoxy resin (EP). Compared with pure EP, the peak heat release rate (pHRR), total heat release (THR), peak smoke production rate (pSPR), total smoke production (TSP), peak CO production rate (pCOPR), and peak CO 2 production rate (pCO 2 PR) of EP/Mn 3 CoO x are reduced by 47.5 %, 21.5 %, 34.6 %, 17.6 %, 58.6 %, and 55.4 %, respectively. It has been shown that Mn 3 CoO x not only catalyzes the formation of high-quality char layer but also effectively catalyzes the conversion of hazardous gas products into CO 2. Recovery experiments of Mn 3 CoO x filler in EP composites show that the recovery of Mn 3 CoO x can reach 90.0 %. This work provides insights into the design of efficient metal oxide flame retardants and ideas for the development of recycled flame retardants. [Display omitted] [ABSTRACT FROM AUTHOR]

With the specialization and diversification of the use environment of composite products, composite materials should have good comprehensive properties. Abiding by this target, we successfully prepared a transparent epoxy resin (EP) composite with flame retardancy, low smoke, enhanced toughness, high glass transition temperature by blending the flame-retardant POI synthesized in this work. POI was synthesized from phosphophenanthrene, vanillin and histidine, and the combination of these three raw meticulously selected endowed POI molecule with excellent versatility. EP composite modified with 10 wt% POI (EP/POI-10) obtained a limiting oxygen index (LOI) of 30.5% and received the V-0 grade (UL-94). The reduction of total smoke production by 78.1% via cone calorimeter tests was obtained. The impact strength of EP/POI-7 increased by 48.2% due to the energy dissipation of cracks from POI. The comprehensive analysis of the dual-phase revealed that the improvement of flame retardance was attributed to the joint action of the gaseous phosphorus free radicals quenching and the protecting of condensed coke. Moreover, EP/POI obtained high glass transition temperature as well as good transparency. [Display omitted] • A bio-based flame retardant molecule POI was synthesized. • High-performance composites of EP/POI with high T g , toughened and transparent were prepared. • The EP/POI showed a remarkable smoke suppression effect with a 78.1% reduction in TSP. [ABSTRACT FROM AUTHOR]

• A bio-based flame retardant (FDI) was synthesized for epoxy resin. • FDI endows EP with excellent flame retardancy and low dielectric properties. • The introduction of FDI significantly improved the toughness of epoxy resin. The development of high-performance EP composites with high glass transition temperature (T g), excellent flame retardancy, and UV resistance is a challenging topic in the flame retardancy community. In this work, a bio-based phosphorus/nitrogen/sulfur (P/N/S) containing flame retardant (FDI) was prepared from furfural, 2-amino-5-nitrothiazole, and DOPO. It was applied to improve the flame retardant, dielectric, and UV-resistant properties of EP. Thanks to the combination of phosphorus, nitrogen, and sulfur in FDI, the EP/FDI composites showed superior flame retardancy. Only adding 5 wt% FDI made EP achieve UL-94 V-0 flammability rating with a limiting oxygen index (LOI) of 27%. Meanwhile, EP/FDI-5% composite showed significant reduction of 65.1% and 33.6% in total smoke production (TSP) and the peak heat release rate (pHRR), respectively. The flame-retardant mechanisms of EP/FDI thermosets were investigated by residual char photographs, SEM, XPS, and Py/GC-MS. Moreover, compared to pure EP, EP/FDI composites showed excellent UV resistance, low dielectric properties, and high glass transition temperature, which was expected to be extensively used in multiple areas of production. [ABSTRACT FROM AUTHOR]

[Display omitted] • A cubic metal organic flame retardant with single crystal structure and rich in nitrogen was synthesized by hydrothermal method. • The peak heat release rate of EP composite loaded with 9 phr R1-MOF decreased by 51.3%. • Flame retardant shows high flame retardancy and smoke suppression performance, and significantly reduces the toxicity of EP. • Synergistic flame retardancy between N element and metal ions in metal organic framework ligands. Toxic substances released during the combustion of epoxy resin (EP) not only cause casualties, but also pollute the environment. Hence, aiming at the flammability of EP, a new triazine based metal organic framework (R1-MOF) was successfully synthesized by solvothermal method to reduce the fire resistance of EP. The single crystal structure of MOF was determined by X-ray single crystal diffraction, and the regular hexahedral structure of the crystal was determined by scanning electron microscope. The peak heat release rate, smoke generation rate, CO generation and CO 2 generation of EP composite loaded with 9 per 100 parts of matrix resin (phr) of R1-MOFs were decreased by 51.3, 41.5, 45.3, and 39.1%, respectively, showing high flame retardancy and smoke suppression performance, and significantly reducing the toxicity of EP. It mainly benefited from the flame retardant N element in MOF ligand and the synergistic effect between ligand and metal ions. In this study, a new type of MOF flame retardant was proposed, which provided a new way to design efficient flame retardants, smoke suppressants and detoxification flame retardants. [ABSTRACT FROM AUTHOR]