A semi-global reaction mechanism for the thermal decomposition of low-density polyethylene blended with ammonium polyphosphate and pentaerythritol

Coimbra, Alain; Sarazin, Johan; Bourbigot, Serge; Legros, Guillaume; Consalvi, Jean-Louis

doi:10.1016/j.firesaf.2022.103649

Cited by 10 publications

(5 citation statements)

References 45 publications

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“…The melt blended mixture was discharged onto a plate‐vulcanizing machine hot pressing at 160°C for 5 min and cold pressing at room temperature for 5 min to obtained the samples for various tests. The mass ratio of APP/PER = 3 was selected as it can lead to the formation of an intumescent maximum 27,28 . The optimum ratio of AHP, APP and PER was ascertained as 1: 4.5: 1.5 based on the results of small flame test.…”

Section: Methodsmentioning

confidence: 99%

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Improving the flame retardancy efficiency and mechanical properties of the intumescent flame retarded low‐density polyethylene by the dual actions of polyurea microencapsulation and aluminum hypophosphite

Lan

Gao

Xiao

et al. 2023

J of Applied Polymer Sci

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The use of intumescent flame retardants to retard polyethylene usually had the disadvantages of low flame retardancy efficiency and poor compatibility between intumescent flame retardants and low-density polyethylene (LDPE), which led to the reduction of mechanical properties of materials. In order to solve these issues, the microencapsulated ammonium polyphosphate (MAPP) and microencapsulated aluminum hypophosphite (MAHP) with polyurea were prepared through the interfacial polymerization of water-in-oil (W/O) microemulsions. The flame retarded polyethylene composites with MAPP and MAHP were manufactured. The LDPE composites with 17.3 wt% of MAPP and 3.9 wt% of MAHP possessed a LOI value of 27.3% and achieved the V-0 standard. The PHRR and THR were remarkably decreased by 30.3% and 31.1% compared with that of the LDPE. Furthermore, the tensile strength of LDPE/MAPP-MAHP was 19.1% higher than that of LDPE/APP-AHP because of good dispersion and compatibility of MAPP and MAHP with LDPE. This work provides a new method to prepare flame-retardant LDPE with high performance and the related mechanisms were discussed in detail.

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Section: Methodsmentioning

confidence: 99%

“…The mass ratio of APP/PER = 3 was selected as it can lead to the formation of an intumescent maximum. 27,28 The optimum ratio of AHP, APP and PER was ascertained as 1: 4.5: 1.5 based on the results of small flame test. The formulations under investigation were listed in Table 1.…”

Section: Preparation Of the Flame Retarded Ldpe Compositesmentioning

confidence: 99%

Improving the flame retardancy efficiency and mechanical properties of the intumescent flame retarded low‐density polyethylene by the dual actions of polyurea microencapsulation and aluminum hypophosphite

Lan

Gao

Xiao

et al. 2023

J of Applied Polymer Sci

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“…70 The degradations of APP and PER generated a carbonaceous charred layer which slightly increased the maximum degradation temperature to 499.3°C and decreased the maximum rate by 19.5%. 71 Also, it was determined that FA additions slightly further increased the maximum degradation temperatures and decreased the maximum rate by 30.8%. In addition, the residues of composites at 1000°C increased with the additions of IFR and FA.…”

Section: Thermogravimetric Analyses Of the Samplesmentioning

confidence: 98%

Effects of fly ash and intumescent flame retardant on thermal, burning, and mechanical properties of polyethylene composites

Demiryuğuran,

Usta

2023

Journal of Thermoplastic Composite Materials

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In this study, fly ash (FA) which mainly consists of SiO2, Al2O3, Fe2O3, MgO, and CaO, was used as a synergistic additive (1–5 wt %) to improve the effectiveness of an intumescent flame retardant (IFR) system (25 wt %) in high density polyethylene (HDPE). IFR system composed of ammonium polyphosphate and pentaerythritol (3/1 ratio), and different amounts of FA were incorporated homogeneously into HDPE. Thermogravimetric analyses and thermal conductivity measurements were performed to determine the thermal properties. Meanwhile, limiting oxygen index, UL 94 vertical burning, and cone calorimetry tests were performed to investigate the fire resistance. Furthermore, the effects of IFR/FA additions on the mechanical properties were determined. The experimental results showed that IFR and IFR/FA additions resulted in early degradation with lower rates, and the residual mass values increased due to the char layers and the FA content. Also, IFR addition increased the thermal conductivity coefficient from 0.451 W/mK to 0.462 W/mK and IFR/FA additions further increased the coefficient up to 0.506 W/mK. Although the sample included only 25 wt % IFR could meet the requirements of UL 94 V-2 with a LOI value of 25.0%, 2, 3 and 4 wt % FA additions satisfied the criteria of UL 94 V-0 with a LOI value of 26.6%. In addition, the cone calorimeter results revealed that the peak heat release rates and total heat released values decreased with IFR (25 wt %) and FA (2, 3, and 4 wt %) additions. Furthermore, CO, CO2, and soot emissions of the composites significantly reduced with respect to HDPE. The NO increased with IFR additions due to the nitrogen content of APP. 25% IFR addition caused decreases in the tensile strength, tensile modulus, and Izod impact strength. However, FA additions slightly enhanced the mechanical properties of HDPE/IFR composite.

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“…However, they require further comments. First, analysis of the pyrolysis process of LDPE shows that it is more complex than a simple phase change [27]. Second, metallic core temperature measurements [28] have revealed that the metal core temperature does not exhibit the constant temperature behavior observed in Figure 2 in the pyrolysis region but increases continuously up to the peak.…”

Section: Model Assumptionsmentioning

confidence: 99%

An engineering model for creeping flame spread over idealized electrical wires in microgravity

Coimbra¹,

Li²,

Guibaud³

et al. 2023

Comptes Rendus. Mécanique

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Flame spread over an insulated electrical wire is a major source of fire scenario in a space vehicle. In this work, an engineering model that predicts the creeping flame spread over cylindrical wires in microgravity is developed. The model is applied to interpret experimental data obtained in parabolic flights for wires composed by a 0.25 mm radius nickel-chromium (NiCr) metallic core coated by low-density polyethylene (LDPE) of different thicknesses ranging from 0.15 mm to 0.4 mm. The model relies on the assumption that, in the pyrolysis region, the NiCr and the LDPE are in thermal equilibrium. This assumption is supported by more detailed numerical simulations and the model reduces then to solving the heat transfer equations for both NiCr and LDPE in the pyrolysis region and in the region ahead of the flame front along with a simple degradation model for LDPE, an Oseen approximation of opposed oxidizer flow and an infinitely fast gas-phase chemistry. The flame spread rate (FSR) is controlled by two model parameters, which are measurable from intrinsic material and ambient gas properties: the convective flame heat flux transferred to the solid ahead from the flame front and the gaseous thermal heat length near the flame front. These parameters are then calibrated from experimental data for a given wire geometry and the calibrated model is validated against experimental data for other wire geometries and ambient conditions. The heat transfer mechanisms ahead of the pyrolysis front are investigated with a special emphasis on the LDPE thickness and the conductivity of the metallic core. In addition to NiCr, metallic cores of lower and higher conductivities are considered. The polymer is shown to be thermally thick for all tested wire geometries and core conductivities. The flame heat flux is found to dominate the heat transfer in the preheat zone where it applies. The core has

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A semi-global reaction mechanism for the thermal decomposition of low-density polyethylene blended with ammonium polyphosphate and pentaerythritol

Cited by 10 publications

References 45 publications

Improving the flame retardancy efficiency and mechanical properties of the intumescent flame retarded low‐density polyethylene by the dual actions of polyurea microencapsulation and aluminum hypophosphite

Improving the flame retardancy efficiency and mechanical properties of the intumescent flame retarded low‐density polyethylene by the dual actions of polyurea microencapsulation and aluminum hypophosphite

Effects of fly ash and intumescent flame retardant on thermal, burning, and mechanical properties of polyethylene composites

An engineering model for creeping flame spread over idealized electrical wires in microgravity

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