scholarly journals Numerical Simulation of Flame Retardant Polymers Using a Combined Eulerian–Lagrangian Finite Element Formulation

2021 ◽  
Vol 11 (13) ◽  
pp. 5952
Author(s):  
Julio Marti ◽  
Jimena de la Vega ◽  
De-Yi Wang ◽  
Eugenio Oñate
Keyword(s):  
Finite Element ◽  
Flame Retardant ◽  
Flame Retardants ◽  
Fire Behavior ◽  
Numerical Results ◽  
Temperature Evolution ◽  
Element Formulation ◽  
Eulerian Formulation ◽  
Lagrangian Finite Element ◽  
Ul 94

Many polymer-made objects show a trend of melting and dripping in fire, a behavior that may be modified by adding flame retardants (FRs). These affect materials properties, e.g., heat absorption and viscosity. In this paper, the effect of a flame retardant on the fire behavior of polymers in the UL 94 scenario is studied. This goal is achieved essentially by applying a new computational strategy that combines the particle finite element method for the polymer with an Eulerian formulation for air. The sample selected is a polypropylene (PP) with magnesium hydroxide at 30 wt.%. For modelling, values of density, conductivity, specific heat, viscosity, and Arrhenius coefficients are obtained from different literature sources, and experimental characterization is performed. However, to alleviate the missing viscosity at a high temperature, three viscosity curves are introduced on the basis of the viscosity curve provided by NIST and the images of the test. In the experiment, we burn the specimen under the UL 94 condition, recording the process and measuring the temperature evolution by means of three thermocouples. The UL 94 test is solved, validating the methodology and quantifying the effect of FR on the dripping behavior. The numerical results prove that well-adjusted viscosity is crucial to achieving good agreement between the experimental and numerical results in terms of the shape of the polymer and the temperature evolution inside the polymer.

Flame Retardant Epoxy Resins Containing Microcapsules

2011 ◽  
Vol 197-198 ◽  
pp. 1346-1349 ◽  
Author(s):  
Fa Chao Wu
Keyword(s):  
Flame Retardant ◽  
Cone Calorimeter ◽  
Epoxy Resins ◽  
Flame Retardants ◽  
Melamine Resin ◽  
Element Analysis ◽  
Ul 94

Bis(2,6,7-trioxa-l-phosphabicyclo[2.2.2]octane-4-methanol) melaminium salt (Melabis) and microcapsules of Melabis with melamine resin shell as flame retardants (FR), respectively, were synthesized. Their structures were characterized by NMR, IR, SEM, TG and element analysis. 20% weight of microcapsules was doped into epoxy resins (EP) to get 28.5 % of LOI and UL 94 V-0. The heat and smoke release of EP containing microcapsules was valued by cone calorimeter.

scholarly journals Effects of a Phosphorus Flame Retardant System on the Mechanical and Fire Behavior of Microcellular ABS

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 30 ◽  
Author(s):  
Vera Realinho ◽  
David Arencón ◽  
Marcelo Antunes ◽  
José Velasco
Keyword(s):  
Flame Retardant ◽  
Impact Energy ◽  
Weight Reduction ◽  
Flame Retardants ◽  
Mechanical Performance ◽  
Fire Behavior ◽  
Acrylonitrile Butadiene Styrene ◽  
Injection Molding Process ◽  
Molding Process ◽  
The Impact

The present work deals with the study of phosphorus flame retardant microcellular acrylonitrile–butadiene–styrene (ABS) parts and the effects of weight reduction on the fire and mechanical performance. Phosphorus-based flame retardant additives (PFR), aluminum diethylphosphinate and ammonium polyphosphate, were used as a more environmentally friendly alternative to halogenated flame retardants. A 25 wt % of such PFR system was added to the polymer using a co-rotating twin-screw extruder. Subsequently, microcellular parts with 10, 15, and 20% of nominal weight reduction were prepared using a MuCell® injection-molding process. The results indicate that the presence of PFR particles increased the storage modulus and decreased the impact energy determined by means of dynamic-mechanical-thermal analysis and falling weight impact tests respectively. Nevertheless, the reduction of impact energy was found to be lower in ABS/PFR samples than in neat ABS with increasing weight reduction. This effect was attributed to the lower cell sizes and higher cell densities of the microcellular core of ABS/PFR parts. All ABS/PFR foams showed a self-extinguishing behavior under UL-94 burning vertical tests, independently of the weight reduction. Gradual decreases of the second peak of heat release rate and time of combustion with similar intumescent effect were observed with increasing weight reduction under cone calorimeter tests.

scholarly journals Synthesis of Novel Polymeric Acrylate-Based Flame Retardants Containing Two Phosphorus Groups in Different Chemical Environments and Their Influence on the Flammability of Poly (Lactic Acid)

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 778 ◽  
Author(s):  
Jacob Sag ◽  
Philipp Kukla ◽  
Daniela Goedderz ◽  
Hendrik Roch ◽  
Stephan Kabasci ◽  
...  
Keyword(s):  
Flame Retardant ◽  
Mode Of Action ◽  
Flame Retardants ◽  
Fire Behavior ◽  
Heat Fluxes ◽  
Poly Lactic Acid ◽  
Cone Calorimetry ◽  
Scanning Calorimetry ◽  
Fire Scenarios ◽  
Physical Phenomena

Novel polymeric acrylate-based flame retardants (FR 1–4) containing two phosphorus groups in different chemical environments were synthesized in three steps and characterized via nuclear magnetic resonance (NMR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and mass spectrometry (MS). Polylactic acid (PLA) formulations with the synthesized compounds were investigated to evaluate the efficiency of these flame retardants and their mode of action by using TGA, UL94, and cone calorimetry. In order to compare the results a flame retardant polyester containing only one phosphorus group (ItaP) was also investigated in PLA regarding its flame inhibiting effect. Since the fire behavior depends not only on the mode of action of the flame retardants but also strongly on physical phenomena like melt dripping, the flame retardants were also incorporated into PLA with higher viscosity. In the UL94 vertical burning test setup, 10% of the novel flame retardants (FR 1–4) is sufficient to reach a V-0 rating in both PLA types, while a loading of 15% of ItaP is not enough to reach the same classification. Despite their different structure, TGA and cone calorimetry results confirmed a gas phase mechanism mainly responsible for the highly efficient flame retardancy for all compounds. Finally, cone calorimetry tests of the flame retardant PLA with two heat fluxes showed different flame inhibiting efficiencies for different fire scenarios.

Lagrangian Finite Element Formulation to Axisymmetric Liquid Sloshing

2011 ◽  
Author(s):  
Shoichi Yoshida ◽  
Kazuyoshi Sekine ◽  
Tomohiko Tsuchida ◽  
Katsuki Iwata
Keyword(s):  
Finite Element ◽  
Axisymmetric Problem ◽  
Time Integration ◽  
Three Dimensional ◽  
Computer Code ◽  
Element Formulation ◽  
Liquid Storage ◽  
Analysis Technique ◽  
Lagrangian Finite Element ◽  
Spurious Modes

The sloshing analysis of liquid storage tanks by the finite element method is basically categorized into two approaches, Lagrangian approach and Eulerian approach. In the Lagragian approach, the behavior of the fluid is expressed in terms of the displacements at nodal points. The advantage of the Lagragian method is that the computer code can be easily developed to modify an existing structural analysis code. The disadvantage is that some spurious modes are included in the vibration modes. The Lagrangian method is widely used in two- and three-dimensional problems. On the other hand, it has not been reported its applicability to the axisymmetric problem. This paper presents the applicability of the Lagragian method to the axisymmetric sloshing problem. The eigenvalue of an elemental stiffness matrix is analyzed in order to investigate the characteristics of the rotational stiffness to the compressibility of the fluid. As a result, this method is found to be difficult to apply to the axisymmetric problem if the equation of motion is directly solved using time integration. However, it gives the highly precise response solutions if the only sloshing modes are taken out and the modal analysis technique is used.

Quasi-Eulerian Finite Element Formulation for Fluid-Structure Interaction

1980 ◽  
Vol 102 (1) ◽  
pp. 62-69 ◽  
Author(s):  
T. Belytschko ◽  
J. M. Kennedy ◽  
D. F. Schoeberle
Keyword(s):  
Finite Element ◽  
Interaction Analysis ◽  
Fluid Structure Interaction ◽  
General Purpose ◽  
Element Formulation ◽  
Finite Element Program ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Eulerian Formulation ◽  
Element Program

A quasi-Eulerian formulation is developed for fluid-structure interaction analysis in which the fluid nodes are allowed to move independent of the material thus facilitating the treatment of problems with large structural motions. The governing equations are presented in general form and then specialized to two-dimensional plane and axisymmetric geometries. These elements have been incorporated in a general purpose transient finite element program and results are presented for two problems and compared to experimental results.

scholarly journals Preparation of Intercalated Organic Montmorillonite DOPO-MMT by Melting Method and Its Effect on Flame Retardancy to Epoxy Resin

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3496
Author(s):  
Junming Geng ◽  
Jianyu Qin ◽  
Jiyu He
Keyword(s):  
Electron Microscopy ◽  
Flame Retardant ◽  
Epoxy Resin ◽  
Flame Retardancy ◽  
Flame Retardants ◽  
Characterization Methods ◽  
Melting Method ◽  
Organic Montmorillonite ◽  
Ul 94 ◽  
Flame Retardant Properties

An intercalated organic montmorillonite DOPO-MMT was prepared through the melting method using 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as a modifier. Epoxy resin (EP) composites were prepared with DOPO-MMT, DOPO, MMT, and the physical mixtures of DOPO+MMT as flame retardants. The microstructure of the flame retardants and EP samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The flame retardant properties, thermal stability, and residual char structure of the EPs were studied by the limited oxygen index (LOI) test, the UL-94 vertical burning test, thermogravimetric analysis (TGA), the differential scanning calorimeter (DSC) test, the cone calorimeter (CONE) test as well as other characterization methods. The results showed that the intercalated organic montmorillonite DOPO-MMT can be successfully prepared by the melting method and that the MMT is evenly dispersed in the EP/DOPO-MMT composite in the form of nanosheets. The EP/DOPO-MMT nanocomposites showed the optimal flame retardancy (LOI, UL-94, PHRR, etc.) among the EPs with DOPO, MMT, and the physical mixture of DOPO+MMT. The flame-retardant grade of the material reached V-0.

A Simple Total-Lagrangian Finite-Element Formulation for Nonlinear Behavior of Planar Beams

2018 ◽  
Author(s):  
Enrico Babilio ◽  
Stefano Lenci
Keyword(s):  
Finite Element ◽  
Theoretical Model ◽  
Finite Difference ◽  
Shear Angle ◽  
Difference Schemes ◽  
Finite Element Formulation ◽  
Finite Difference Schemes ◽  
Element Formulation ◽  
Beam Model ◽  
Lagrangian Finite Element

The present contribution reports some preliminary results obtained applying a simple finite element formulation, developed for discretizing the partial differential equations of motion of a novel beam model. The theoretical model we are dealing with is geometrically exact, with some peculiarities in comparison with other existing models. In order to study its behavior, some numerical investigations have already been performed through finite difference schemes and other methods and are reported in previous contributions. Those computations have enlightened that the model under analysis turns out to be quite hard to handle numerically, especially in dynamics. Hence, we developed ad hoc the total-lagrangian finite-element formulation we report here. The main differences between the theoretical model and its numerical formulation rely on the fact that in the latter the absolute value of the shear angle is assumed to remain much smaller than unity, and strains are piecewise constant along the beam. The first assumption, which actually simplifies equations, has been taken on the basis of results from previous integrations, mainly through finite difference schemes, which clearly showed that, while other strains can achieve large values in their range of admissibility, shear angle actually remains small. The second assumption led us to define a two-nodes constant-strain finite element, with a fast convergence, in terms of number of elements versus solution accuracy. Although, at the present stage of this ongoing research, we have only early results from finite elements, they appear encouraging and start to shed new light on the behavior of the beam model under analysis.

scholarly journals Chain Extension and Synergistic Flame-Retardant Effect of Aromatic Schiff Base Diepoxide on Polyamide 6/Aluminum Diethylphosphinate Composites

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2217 ◽  
Author(s):  
Tianxiang Liang ◽  
Jianan Cai ◽  
Shumei Liu ◽  
Hualin Lai ◽  
Jianqing Zhao
Keyword(s):  
Schiff Base ◽  
Flame Retardant ◽  
Flame Retardants ◽  
Polyamide 6 ◽  
Chain Extension ◽  
Cone Calorimetry ◽  
The Matrix ◽  
Flame Retarded ◽  
Ul 94 ◽  
Synergistic Flame Retardant

A way to suppress the deterioration in mechanical properties of polyamide 6 (PA6) is required, especially with high loading of flame retardants in the matrix. In this study, a novel aromatic Schiff base diepoxide (DES) was synthesized. It exhibited an efficient chain extension effect on PA6 and a synergistic flame-retardant effect with aluminum diethylphosphinate (AlPi) for PA6. The PA6 composite with 16 wt.% AlPi only passed UL-94 V-0 rating at 1.6 mm thickness, while the combination of 1.5 wt.% DES with 13 wt.% AlPi induced PA6 to achieve a UL-94 V-0 rating at 0.8 mm thickness. The tensile, flexural, and Izod notched impact strengths were increased by 16.2%, 16.5%, and 24.9%, respectively, compared with those of V-0 flame-retarded PA6 composites with 16 wt.% AlPi. The flame-retarded mechanism of PA6/AlPi/DES was investigated by cone calorimetry and infrared characterization of the char residues and pyrolysis products. These results showed that DES had a synergistic effect with AlPi in condensed-phase flame retardation by promoting the production of aluminum phosphorus oxides and polyphosphates in the char residues.

Sign in / Sign up

Export Citation Format

Share Document