Search

It is of great importance to enhance ability of charring formation for polystyrene (PS) to overcome non‐charring feature during burning. Here, we demonstrate a kind of ternary intumescent flame retardant composition composed by a novel ionic liquid butyltriphenylphosphonium‐chelated orthoborates (IL) with self‐expanded flame retardant, ammonium polyphosphate (APP) and expandable graphite (EG), to improve flame retardancy of PS. This ternary composition promotes limited oxygen index (LOI) value to 26.6 ± 0.5% and UL‐94 V0 level for PS composite with 15 wt% total loading. In addition, the peak value of heat release rate and smoke production rate of PS composite with ternary composition are separately reduced by 79.7% and 70.7% comparing to neat PS as well as 44.4% and 29.2% to its IL‐free binary counterpart in cone calorimeter test. Meanwhile, the ternary composition displays compact charring bulk constructed by large‐expansion‐volume vermiform expanded graphite. The TG‐FTIR technique is used to analyze gaseous profiles. The rheological property discloses that expansion behavior of the ternary composition contributes to robust viscoelasticity of composite and advantageous network construction at high temperature. Given the fire performance of the ternary composition, the combination of IFR and IL provides an opportunity for rational design and fabrication of functional flame‐retardant system. [ABSTRACT FROM AUTHOR]

Use of Salen‐phosphazene (Salen‐PZN) complex for flame retardant polymeric materials demonstrate good flame retardancy due to their abundant flame retardant elements and aromatic‐rich structure. To further enhance their flame retardancy and interaction with the matrix, phosphorous (DK) was armed on nickel‐based Salen‐polyphosphazene complex (DK@Salen‐PZN‐Ni) as a smart decoration. The composite with DK decoration has higher tensile strength than the DK‐free composite. Moreover, cone calorimeter study showed that with 3 wt% total additive loading, the peak heat release rate (pHRR) and peak smoke rate (pSPR) of DK@Salen‐PZN‐Ni/EP composite were reduced by 21.0% and 30.3%, respectively when compared with pure EP. The limited oxygen index of the composite was 30.2%, while the vertical burning test (UL‐94) reached the V‐1 rate. Flame retardance mechanism of DK@Salen‐PZN‐Ni was discussed in detail. The designing of flame retardants alleviated the mechanical property failure and improved the flame retardancy of polymeric composite. [ABSTRACT FROM AUTHOR]

Flame retardants (FRs) improve the intrinsic flammability of epoxy resins (EPs). However, the fundamental properties of EPs are inevitably compromised with the improvement of flame retardancy due to addition of FRs. Here, an ionic liquid (IL) octyltriphenylphosphonium‐chelated orthoborate ([OTP][BScB]) has been synthesized and used as a flame‐retarding additive for EP (hereafter (EP/[OTP][BScB])). Themogravimetry analysis (TGA) result indicated that the addition of [OTP][BScB] improved the residue yield during thermal degradation. Flammability and combustion tests showed the superior flame‐retarding efficiency of the IL. More specifically, the addition of 3 wt% IL made EP/[OTP][BScB] pass the V‐0 grade in the vertical burning test (UL‐94) and achieve 32.5% value in the limited oxygen index (LOI) test. Cone calorimeter (CC) test showed that, compared with neat EP, EP/10[OTP][BScB] showed a reduction in the peak heat release rate (PHRR) and total heat release (THR) of by 39.7% and 21.8%, respectively, during combustion. Accordingly, the flame‐retarding mechanisms in the gas and condensed phases were investigated in detail. In addition, tensile tests showed that the incorporation of the IL enhanced the mechanical property of EP/[OTP][BScB] to some extent. Moreover, UV–vis spectroscopy showed that the transparency of EP was basically maintained on the addition of [OTP][BScB]. Therefore, the IL [OTP][BScB] is a promising flame retardant to improve the properties of EP comprehensively. [ABSTRACT FROM AUTHOR]

Herein, we have successfully synthesized phosphorus/nitrogen/silicon tri-elements compound phosphazene derivative hexa-[4-(N -(3-(triethoxysilyl)propyl)acetamide)phenoxy]cyclotriphosphazene (HNTPC) from hexachlorotriphosphazenitrile, methyl 4-hydroxybenzoate, and 3-triethoxysilylpropylamine, and it was used as an additive flame retardant in epoxy resin (EP). Then, the thermal stability and flame retardancy of the composite (HNTPC/EP) were tested. Thermogravimetric analysis showed that the presence of HNTPC made EP matrix decompose at a relatively low temperature, thus promoted the formation of a stable coke layer and protected the matrix from fire. Therefore, the amount of carbon residue was markedly increased at 800°C, indicating an outstanding condensed phase flame-retardant effect. Furthermore, various combustion test data manifested that the addition of HNTPC could significantly improve the flame-retardant performance of EP. In addition, the sample could pass the vertical burning tests (UL-94) V-1 grade when the addition amount was 10% and the limiting oxygen index value was 32.6%, the peak heat release rate and total heat release rate decreased by 40.0% and 21.5%, respectively. Besides, the results of scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy also showed that HNTPC can promote the formation of carbon layer and improved the flame-retardant property of EP. Finally, the condensed phase and gas phase synergistic flame-retardant mechanism of HNTPC was proposed. [ABSTRACT FROM AUTHOR]

Polystyrene (PS) with great flame retardancy has been achieved by addition of polyhedral oligomeric silsesquioxane (POSS). However, the POSS/PS composite showed easy-ignition behavior leading to fire hazard exposed. Aiming to prolong time to ignition (TTI) and improve flame retardancy simultaneously, using non-flammable modifier to decorate POSS is a facile method. Here, two kinds of POSS hybrids (POSS-ILs), denoted as POSS-EVIM and POSS-VIPSP, were synthesized by free radical copolymerization between vinyl POSS and two kinds of ionic liquid, commercial [EVIm]BF4 and Brønsted ionic liquid, respectively. The polystyrene-based composites (POSS-ILs/PS) were prepared by incorporated POSS-ILs into polystyrene. The results of thermal gravimetric analysis test evidenced that both POSS-ILs increased char yield and decreased decomposed rate of composites. Compared with neat PS, the TTI of POSS-ILs/PS was prolonged by 26 s and 21 s, and meanwhile, the fire hazard was decreased due to reduction of peak value of heat release rate (PHRR) and smoke release rate (PSPR) in cone calorimeter test. Scanning electron microscope observed compact residue of POSS-EVIM/PS and honeycombed residual morphology of POSS-VIPSP/PS, and additionally, both of these residual char possessed higher degree of graphitization than that of PS and POSS/PS in Raman spectrum, suggesting good physical barrier for matrix from heat and oxygen. Besides, the flexural strength of both POSS-ILs/PS composites were increased compared with neat PS. Taking the results above mentioned, POSS modified by ionic liquid can be a decent candidate to prolong time to ignition, simultaneously improve fire safety and mechanical properties for polymeric materials. [ABSTRACT FROM AUTHOR]

A novel poly(methyl methacrylate) (PMMA)‐based copolymer (PMMA‐co‐BDPA) rich in aromatic rings was synthesized via radical copolymerization between a phosphorus‐containing acrylic monomer (BDPA) and methyl methacrylate (MMA). UV‐vis spectroscopy demonstrated that the copolymer had high transparency. Thermogravimetric analysis (TGA) and a differential scanning calorimeter (DSC) were used to test the thermal properties of the composites. Additionally, the PMMA‐co‐BDPA‐15 copolymer exhibited a 23% increase in the limited oxygen index (LOI) value. A cone calorimeter test indicated that the peak heat release rate (pk‐HRR) of PMMA‐co‐BDPA was reduced by 29.2% compared with that of pure PMMA, and the carbon yield of burning was obviously increased. The combined test results demonstrated that the prepared copolymer material had good transparency, thermal stability, and flame retardancy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesized phosphorus-containing organic porous polymers (PPOPs) for thermal insulation and flame retardancy. • PPOPs have low thermal conductivity and excellent flame retardant properties. • Loading PPOPs improved the flame retardant and mechanical properties of EP. • PPOPs can be designed into different shapes for practical applications. Developing porous functional materials with good thermal insulation and flame retardant properties is of great importance in modern eco-friendly buildings. Herein, we report the one-step synthesis of imine chain monolithic porous phosphorus-containing organic porous polymers (PPOPs) using Schiff base polycondensation reaction and as an example of efficient thermal insulation and flame retardant. Experimental results show that the PPOPs have low thermal conductivity (0.055 W·m−1·K−1) and excellent flame retardant properties. Measurements by microcalorimetry (MCC) showed a peak heat release rate (pHRR) value was 23.9 W·g−1, which is nearly an order of magnitude lower than that of most currently reported flame retardant materials. Using PPOPs in the epoxy resin (EP) matrix, the prepared EP composites exhibited excellent flame retardant properties. Cone calorimeter (CC) tests showed that the peak heat release rate (pHRR) and peak smoke release rate (pSPR) during combustion of PPOPs/EP composites were reduced by 42.0% and 36.4%, respectively, compared with pure EP. Tensile tests showed that the addition of PPOPs improved the mechanical properties of the composites to some extent. In addition, PPOPs can be designed into different shapes for practical applications compared with those fragile inorganic insulation materials and powders that were usually non-processable. Taking these advantages into account, PPOPs have great potential for modern building applications as monolithic foams or coatings with both excellent flame retardancy and thermal insulation properties. [ABSTRACT FROM AUTHOR]