Foam Decomposition Research Articles

ТЕРМОСТОЙКОСТЬ ЗАЛИВОЧНЫХ ПЕНОПОЛИИЗОЦИАНУРАТОВ

In the modern construction industry for increasing the thermal resistance of structures and reducing heat losses, casting foams based on reactive oligomers with high performance characteristics are widely used. At the same time, special attention is paid to the use of polyisocyanurate foams (PIR). However, in the scientific and technical literature there are practically no data on the influence of the composition of polyisocyanurate foams on their thermal properties. The purpose of this work is to determine the influence of isocyanate/polyol ratio, modifier content (trichloropropyl phosphate) and apparent density of foams on thermal properties of casting PIRs. The thermal properties of PIRs, when heated in the temperature range of 30-800 ⁰C in nitrogen atmosphere and in air, were investigated using a multimodal thermal analytical complex DuPont-9900 (heating rate 20°C/min). It is revealed that thermo-oxidative decomposition of polyisocyanurate foams is a pronounced, two-stage process, and the destruction of PIR in inert medium (nitrogen) is a one-stage process, which indicates different mechanisms of decomposition of foams in air and nitrogen. As a result of experimental studies, it was revealed that the investigated PIRs are more resistant to thermo-oxidative degradation than to thermal degradation. The thermal properties of the above foams depend on the isocyanate/polyol ratio and TCPP content. The density of polyisocyanurate foams insignificantly affects their thermal stability. At the optimal content of initial components PIRs have higher thermal resistance compared to rigid polyurethane foams (FPU).

Experimental Study on the Kinetics of the Natural Gas Hydration Process with a NiMnGa Micro-/Nanofluid in a Static Suspension System

Natural gas is a resource-rich clean energy source, and natural gas hydration technology is a promising method for natural gas storage and transportation at present. To realize the rapid generation of hydrates with a high gas storage capacity, in this paper NiMnGa micro/nanoparticles (NMGs) with different mass fractions (0.1 wt%, 1 wt%, 2 wt%) were prepared with 0.05 wt% sodium dodecyl sulfate (SDS) and 1 wt% L-tryptophan to form static suspension solutions of gellan gum, and the methane hydration separation kinetics experiments were carried out under the condition of 6.2 MPa for the SDS-NMG-SNG (SNG) and L-tryptophan-NMG-LNG (LNG) systems. The results showed that the induction time of the systems with NMG micro-/nanoparticles was shortened to different degrees and the gas consumption rate was increased. The best effect was achieved in the SNG system with 1 wt% NMG, and the induction time was shortened by 73.6% compared with the SDS-gellan system (SG). The gas consumption rate of the system with L-tryptophan was better than that of the system with SDS, and the best effect was achieved in the system with 2 wt% NMG. The system with 2 wt% NMG had the best effect, and the problem of foam decomposition did not occur. The analysis concluded that NMG has strong mass transfer and phase-change heat absorption properties, which can significantly improve the kinetics of the natural gas hydrate generation process; L-tryptophan can weaken the diffusion resistance of methane molecules in the suspended static solution, further enhancing the mass transfer of the hydrate generation process. These findings will provide new perspectives regarding the application of phase-change micro-/nanoparticles in methane hydrate generation under static conditions.

Synthesis, antibacterial activity, and enzymatic decomposition of bio-polyurethane foams containing propolis

Polyurethane foam (PUF) is formed by reacting sugar, propolis, and polyisocyanate, and then blowing with CO2, formed by reacting polyisocyanate with water. An optimum foaming rate of 1440% was found for 15 wt.% of sugar and 20 wt.% of propolis, and the synthesis and cell structure of polyurethane were analyzed by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. Under the optimized conditions, the apparent density and thermal conductivity of the PUF-containing propolis were 0.04 – 0.147 g/mL and 0.028 – 0.029 W/(mK), respectively. The bacterial reduction rate was 92.7% in the PUF containing 20 wt.% propolis. PUF can be broken down by enzymatic reactions in water using invertase. The degradation reaction of invertase was kinetically analyzed. This study showed that eco-friendly polymers can be synthesized using sugar and propolis and decomposed through antibacterial activity and enzymatic green recycling.

An Application of Analytical Hierarchy Process in Selection of Coating Material Composition in Lost Foam Casting Process

In modern industrial era, the dimensional accuracy and surface finish are two major criteria in the selection of casting process. To achieve this paradise, lost foam casting is one of the casting processes. In this casting process, the shell is made by removal of expandable polystyrene or foam pattern with the application of heat. During the foam decomposition process, many problems have been generated such as bending, expansion, distending and crack of the shell. These problems may be eliminated by selecting the optimum ratio of coating materials. In this research work, zircon and aluminium silicate refractory coating materials with sodium silicate binder have been used with different composition and prepared the four test samples from them. For selection of best shell material composition, analytical hierarchy process is used.

TG/DTA-FTIR as a method for analysis of tall oil based rigid polyurethane foam decomposition gaseous products in a low oxygen environment

This study is an investigation of the suitability of the thermogravimetry and differential thermal analysis method coupled with Fourier Transform Infrared spectrometry (TG/DTA-FTIR) for a thermal degradation gaseous product analysis of a rigid polyurethane-polyisocyanurate (PU-PIR) foam synthesised from high functionality tall oil fatty acids (TOFA) based polyols. The FTIR spectra of the TG-generated gaseous thermal degradation products of three PU-PIR formulations with varied high functionality TO based polyol content (45, 75 and 95 pbw) and a different tier of isocyanate (NCO) indexes (110, 150, 200, 300 and 400) for each formulation were compared to the spectra of a formulation developed using conventional raw materials. The chemical bands of known chemical compounds and unknown compounds containing specific groups for the foams were evaluated; the focus was on the maximum release rate for specific chemical compounds (CO2; –NCO; H2O; CO) to determine the temperature zone values of the main thermal degradation phases. The experiments were carried out at a low oxygen environment, providing valuable data on the trends for the excretion of specific gaseous substances from the rigid PU-PUR foam that could be released in a real fire, where organic building materials that possess a porous matrix might be present and the nature of the combustion process is predominantly heterogeneous oxidation.

Thermal decomposition of flexible polyurethane foams in air

The oxidative thermal decomposition of a non-fire retardant and a fire retardant polyurethane foam is investigated using thermogravimetric analysis and differential scanning calorimetry over 1–60 °C/min of heating rate, in both air and nitrogen environments. From the thermogravimetry results, the oxidative environment of air results in additional oxidative reactions which are heating rate dependent. These reactions compete with the pyrolysis reactions for the same reactants over similar temperature range. For both foams, increasing heating rate gradually reduces the influence from the oxidation of foam while favouring the pyrolysis of polyol. At low heating rate, in oxidative air environment, the fire retardant foam shows significant decomposition across low temperature range. This environment mimics the incipient phase of a fire, and ignition inhibition is possible when this low temperature decomposition is coupled with gas phase fire retardant mechanisms such as neutralisation of reactive radicals. Fire retardant additives also form char residue which notably lowers the decomposition rate while extending the decomposition temperature range, improving the overall thermal stability. Lastly, the kinetic properties governing the oxidative thermal decomposition of foams are estimated graphically using Inflection Point Methods, and the corresponding exothermic heat of reaction is determined from the heat flow results.

Comparative study on the pyrolysis kinetics of polyurethane foam from waste refrigerators.

Thermal treatment offers advantages of significant volume reduction and energy recovery for the polyurethane foam from waste refrigerators. In this work, the pyrolysis kinetics of polyurethane foam was investigated using the model-fitting, model-free and distributed activation energy model methods. The thermogravimetric analysis indicated that the polyurethane foam decomposition could be divided into three stages with temperatures of 38°C-400°C, 400°C-550°C and 550°C-1000°C. Peak temperatures for the major decomposition stage (<400°C) were determined as 324°C, 342°C and 344°C for heating rates of 5, 15 and 25 K min-1, respectively. The activation energy (Eα) from the Friedman, Flynn-Wall-Ozawa and Tang methods increased with degree of conversion (α) in the range of 0.05 to 0.5. The coefficients from the Flynn-Wall-Ozawa method were larger and the resulted Eα values fell into the range of 163.980-328.190 kJ mol-1 with an average of 206.099 kJ mol-1. For the Coats-Redfern method, the diffusion models offered higher coefficients, but the E values were smaller than that from the Flynn-Wall-Ozawa method. The Eα values derived from the distributed activation energy model method were determined as 163.536-334.231 kJ mol-1, with an average of 206.799 kJ mol-1. The peak of activation energy distribution curve was located at 205.929 kJ mol-1, consistent with the thermogravimetric results. The Flynn-Wall-Ozawa and distributed activation energy model methods were more reliable for describing the polyurethane foam pyrolysis process.

Bio‐based engineered nanocomposite foam with enhanced mechanical and thermal barrier properties

ABSTRACTBio‐based polyurethane (PU) foams were developed from bio‐polyol (castor oil‐based) in the presence of selective catalyst, surfactant, and blowing agent. Bentonite nanoclay (NC) was incorporated into the bio‐polyol mixture as nano‐reinforcement, while, triethyl phosphate was used as flame‐retardant agent. After fabrication, these bioengineered foam nano‐composites were studied for microstructural, mechanical and thermal characterizations. Fourier transform infrared spectroscopy analysis indicated the presence of characteristic functionalities within biopolyol segments, which was influenced by reactant activity within the polyurethane (PU) foams. Scanning electron microscopy revealed the cellular morphology of the foam. Thermogravimetric analysis enabled the study of foam decomposition behavior for different sample compositions. Incorporation of NC into pristine foam was found to delay the onset degradation temperature. Flammability studies depicted significant enhancement of flame retardancy with incorporation of NC up to a certain loading level. Compression tests demonstrated that significant improvement of compressive strength properties of foams could be achieved by incorporating bentonite nanoclay, owing to nucleation effect of nanoclay and corresponding enhanced structural integrity. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47063.

Density predictions using a finite element/level set model of polyurethane foam expansion and polymerization

Polyurethane foams are used widely for encapsulation and structural purposes because they are inexpensive, straightforward to process, amenable to a wide range of density variations (1–50 lb/ft3), and able to fill complex molds quickly and effectively. Computational models of the filling and curing process are needed to reduce defects such as voids, out-of-specification density, density gradients, foam decomposition from high temperatures due to exotherms, and incomplete filling. This paper details the development of a computational fluid dynamics model of a moderate density PMDI structural foam, PMDI-10. PMDI is an isocyanate-based polyurethane foam, which is chemically blown with water. The polyol reacts with isocyanate to produce the polymer. PMDI-10 is catalyzed giving it a short pot life, meaning that the foam is liquid and flowable only for a short-time; it foams and polymerizes to a solid within 5 min during normal processing. To achieve a higher density, the foam is over-packed to twice or more of its free-rise density of 10 lb/ft3. The goal for modeling is to represent the expansion, filling of molds, and the polymerization of the foam. This model will be used to reduce defects, optimize the mold design, understand processing parameter sensitivities, and predict the final foam properties.A homogenized continuum model for foaming and curing was developed based on reaction kinetics, documented in a recent paper; it uses a simplified mathematical formalism that decouples these two reactions. The chemo-rheology of PMDI is measured experimentally and fit to a generalized-Newtonian viscosity model that is dependent on the extent of cure, gas volume fraction, and temperature. The conservation equations, including the equations of motion, an energy balance, and three rate equations are solved using a stabilized finite element method. The equations are combined with a level set method to determine the location of the foam-gas interface as it evolves to fill the mold. Understanding the thermal history and loads on the foam due to exothermicity and oven curing is very important to the results, since the kinetics, viscosity, and other material properties are all sensitive to temperature. Results from the model are compared to experimental flow visualization data to understand the interface evolution with time and post-test X-ray computed tomography (CT) data for the density prediction validation. Several geometries are investigated including two configurations of a mock structural part and a bar geometry to specifically test the density model. We have found that the model predicts both average density and filling profiles well. However, it under predicts density gradients, especially in the gravity direction. Further model improvements are also discussed for future work.

One-Pot Synthesis of P(O)-N Containing Compounds Using N-Chlorosuccinimide and Their Influence in Thermal Decomposition of PU Foams.

Synthesis of intermediate containing P(O)-Cl bonds is the key to converting P(O)-H bonds to P(O)-N. In this work we have performed chlorination reactions of different H-phosphinates and H-phosphonates using N-chlorosuccinimide as an environmentally-benign chlorinating agent. The chlorination reaction showed high yield and high selectivity for transformation of P(O)-H bonds into P(O)-Cl analogues, resulting in an easily separable succinimide as the by-product. Using a one-pot synthesis methodology, we have synthesized a series of P(O)-N containing derivatives whose synthesis was found to be dependent on the reaction solvents and the starting materials. The synthesized P(O)-N compounds were incorporated in flexible polyurethane foam (FPUF) and screened for their influence in thermal decomposition of FPUFs using thermogravimetric analysis (TGA) and a microscale combustion calorimeter (MCC). All solid P(O)-N compounds influenced the first-stage decomposition of FPUFs, which resulted in an accelerated decomposition or temporary stabilization of this stage. However, the liquid P(O)-N derivatives volatilize at an earlier stage and could be active in the gas phase. In addition, they also work in condensed phase via acid catalyzed decomposition for FPUFs.

Bulk Polymer-Derived Ceramic Composites of Graphene Oxide.

Bulk polymer-derived ceramic (PDC) composites of SiCO with an embedded graphene network were produced using graphene-coated poly(vinyl alcohol) (PVA) foams as templates. The pyrolysis of green bodies containing cross-linked polysiloxane, PVA foams, and graphene oxide (GO) resulted in the decomposition of PVA foams, compression of GO layers, and formation of graphitic domains adjacent to GO within the SiCO composite, leading to SiCO composites with an embedded graphene network. The SiCO/GO composite, with about 1.5% GO in the ceramic matrix, offered an increase in the electrical conductivity by more than 4 orders of magnitude compared to that of pure SiCO ceramics. Additionally, the unique graphene network in the SiCO demonstrated a drop in the observed thermal conductivity of the composite (∼0.8 W m–1 K–1). Young’s modulus of the as-fabricated SiCO/GO composites was found to be around 210 MPa, which is notably higher than the reported values for similar composites fabricated from only ceramic precursors and PVA foams. The present approach demonstrates a facile and cost-effective method of producing bulk PDC composites with high electrical conductivity, good thermal stability, and low thermal conductivity.

Thermogravimetric and qualitative analysis of thermal decomposition characteristics of polyurethane foams based on polyols with carbamide or oxamide and borate groups

The thermal stability and the kinds of products of thermal decomposition of polyurethane foams modified with urea or oxamide and borate groups were studied. Incorporation of urea or oxamide groups and borate groups enhances the thermal stability of polyurethane foams compared to polyurethane foams based on typical polyols. Thermal stability of foams modified with oxamide groups is somewhat higher that of foams modified with urea groups. In turn, simultaneous incorporation of borate groups results in an increase in thermal stability of the foams modified with urea. The temperature of thermal decomposition of the foams with oxamide and borate groups does not change or undergoes a slight decrease. The thermal degradation products of investigated foams are similar and they are usually water, ammonia, carbon dioxide and/or nitrous oxide. Additionally, hydrogen cyanide can be released during thermal decomposition of polyurethane foams modified with urea groups. The presence of borate groups prevents the formation of hydrogen cyanide. The opposite situation is observed in the case of the foams modified with oxamide and borate groups. Thus, from the point of view of a fire hazard, the use of the foams modified with urea and borate groups is safer. © 2017 Society of Chemical Industry

Thermal decomposition and flammability of rigid PU foams containing some DOPO derivatives and other phosphorus compounds

A series of 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) based derivatives were synthesized and incorporated as flame retardant additives in rigid polyurethane foam (RPUF). The flame retardant performance of DOPO derivatives in RPUF was investigated and compared with traditional flame retardant tris(1-chloro-2-propyl) phosphate (TCPP) and reactive flame retardant (diol) based on oligomeric ethyl ethylene phosphate (PLF140). The flame retardant performance of rigid foams was evaluated by UL 94 HB test, limiting oxygen index (LOI) and cone calorimetry (CONE). Thermal stability of RPUF samples was analyzed by thermogravimetric analysis (TGA) and pyrolysis combustion flow calorimeter (PCFC). The thermal decomposition mechanism of the flame retardant RPUF and the mode of action of the flame retardants were investigated via pyrolysis-gas chromatography-mass spectrometry (Py-GC–MS) and thermogravimetric analyzer coupled with FTIR and MS (TG-FTIR-MS). Scanning electron microscope-energy dispersive X-ray (SEM-EDX) was used to analyze the char residue of the RPUF. It was observed that, addition of 2wt% phosphorus in RPUF helps achieve HF1 rating in UL 94 HB test and reduces the peak of heat release rate by 23%–42% in cone calorimeter measurements. Additionally, in cone calorimeter measurements, compared to RPUF containing TCPP and PLF140, RPUF containing DOPO derivatives exhibit lower smoke and toxicant production and increased char residue. For RPUF containing 6-(2-(4,6-diamino-1,3,5-triazin-2-yl)ethyl) dibenzo[c,e][1,2]oxaphosphinine 6-oxide (DTE-DOPO), production of decomposition products such as –NCO containing compounds, HCN, hydrocarbons, amines and cyanic acid were significantly decreased compared to virgin RPUF. RPUF/DTE-DOPO formulation resulted in a compact and tough char structure which proves its strong barrier effect in the condensed phase. The detailed flame retardant mechanisms of TCPP and DTE-DOPO in RPUF are further elaborated in this work.

Synthesis and characterisation of polyurethane elastomers with semi-products obtained from polyurethane recycling

In this work polyurethane elastomers were synthesised by using different mixtures of a petrochemical and glycerolysate polyols and 4,4-diphenylmethane diisocyanate (MDI). Glycerolysate polyol was produced from polyurethane foam decomposition using crude glycerine as a decomposition agent. The structure and thermal properties of obtained semi-product were similar to the polyol used in the synthesis of original foam. Glycerolysate polyol was incorporated into polyurethane formulation as soft segment (SS). Since polyol is one of the major component in polyurethane system (>70%) introducing recycled components leads to lowering of consumption of petrochemicals and valorisation of recycled products. Polyurethane elastomers containing up to 16.4wt.% of glycerolysate polyol were synthesised, soluble in dimethylformamide (DMF) up to ca. 12wt.%. The effect of glycerolysate polyol content on the structure and properties was analysed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and mechanical tests. Thermal properties did not worsen after using glycerolysate into polyurethane formulation. A slight increase in glass transition temperature is observed with the incorporation of glycerolysate polyol. Elastic modulus, tensile strength and hardness of polyurethane elastomers increased with recycled polyol content. Moreover they showed high elongation at break values.

Polyurethane foams chemically reinforced with POSS—Thermal degradation studies

Thermal degradation of rigid polyurethane foams chemically modified by polyhedral silsesquioxanes was analyzed using hyphenated techniques – thermogravimetry (TG) coupled with FTIR spectroscopy and quadrupole mass chromatography (QMS). Two functionalized POSS were used – PHI-POSS as pendant group to the main PU chain and OCTA-POSS which acts as a chemical crosslinking agent due to the presence of eight OH-terminated side chains.Based on thermogravimetric data, thermal stabilization effect of POSS particles on PU foamed matrix was found and it was evidenced by shift of the initial decomposition temperature. The TG/FTIR/QMS studies showed that the thermal decomposition of polyurethane foams reinforced with POSS starts from about 150°C via urethane linkages scission. In lower temperature region the materials decompose to some low molecular weight compounds and intermediates with ether/ester and alcohol groups. At the temperature above 350°C evolution of hydrocarbons, aldehydes, alcohols, ethers, glycols, amines, cyclic species and low molecular weight compounds—carbon monoxide, carbon dioxide, water and ammonia was recorded. The evolution profiles of degradation products proved that POSS influences the mechanism of PU decomposition.

Pyrolysis of polyurethane foam: optimized search for kinetic properties via simultaneous K–K method, genetic algorithm and elemental analysis

SummaryThis study focuses on the determination of kinetic properties for non‐fire retardant (NFR) and fire retardant (FR) polyurethane foams. Based on the experimental thermogravimetric (TG) curves, this paper describes the application of an in‐depth mathematical analysis and genetic algorithm (GA) to produce the kinetic properties. A recent developed technique, K–K method, is used for calculating kinetic properties and determining the search regions of these properties for GA. Elemental analysis is also used to study the pyrolysis mechanism. Three decomposition models were investigated for comparison, and the results show that the decomposition model with three sub‐reactions achieves the closest representation with experimental results. In the model, two sub‐reactions capture the foam and melt decompositions, and another sub‐reaction with relatively lower activation energy captures the early onset of foam decomposition. The kinetic properties of melt decomposition are found similar because of the similarity of melt chemical formulas and decomposition of NFR and FR foams. The kinetic properties of foam decomposition between NFR and FR foams are different because of the mechanism of FR additives. Validation of the successive and parallel reaction schemes shows no noticeable difference between the two schemes in the modelling decomposition. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Flame retardant flexible polyurethane foams from novel DOPO-phosphonamidate additives

In this work we report synthesis and flame retardant application of novel 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) based phosphonamidates. Two mono and one bis DOPO-phosphonamidates were synthesized and incorporated in polyether based polyurethane (PU) manufacturing process. For the comparison of fire performance of these DOPO-phosphonamidates, we have chosen commercially available flame retardants (TCPP, DOPO and Exolit® OP 560) commonly used in flexible PU foam manufacturing. UL94 HBF fire results of various PU foam formulations indicate that DOPO-phosphonamidates exhibit superior fire performance as compared to the commercial flame retardants. 6,6′-(ethane-1,2-diylbis-(azanediyl)-bis-(6H-dibenzo[c,e][1,2]-oxaphosphine-6-oxide (EDAB-DOPO))/foam formulations exhibit the best fire performance as compared to other DOPO-phosphonamidate/foam formulations. A concentration of only 5% EDAB-DOPO on wt. of polyol is needed to achieve a HF1 rating. Thermal decomposition studies of the DOPO-phosphonamidate/foam formulations indicate their limited condensed phase interaction. In TGA experiments, a very small residue (<5%) was observed at 800 °C for all PU formulations. Additionally EDAB-DOPO showed evidence of intermediate condensed phase interaction in the first stage of PU foam decomposition. Direct insertion probe (DIP) – MS studies indicate that mono DOPO-phosphonamidates volatilize primarily in the first stage of thermal decomposition of PU foams whereas the EDAB-DOPO, being thermally more stable is only detected in gas phase in the second stage. Like in case of TCPP/PU foam formulation, the increase in the CO/CO2 ratio in the cone calorimeter experiments for the DOPO-phosphonamidate/foam formulation further proves the gas phase activity (flame inhibition) of these DOPO-phosphonamidates. EDAB-DOPO being thermally more stable seems to offer more sustained gas phase activity during the entire burning stage of PU foams in cone calorimeter experiments. Higher thermal stability of EDAB-DOPO may explain its superior flame retardant efficacy among all the DOPO-phosphonamidates investigated in this study.

Validation of Heat Transfer, Thermal Decomposition, and Container Pressurization of Polyurethane Foam Using Mean Value and Latin Hypercube Sampling Approaches

Polymer foam encapsulants provide mechanical, electrical, and thermal isolation in engineered systems. It can be advantageous to surround objects of interest, such as electronics, with foams in a hermetically sealed container in order to protect them from hostile environments or from accidents such as fire. In fire environments, gas pressure from thermal decomposition of foams can cause mechanical failure of sealed systems. In this work, a detailed uncertainty quantification study of polymeric methylene diisocyanate (PMDI)-polyether-polyol based polyurethane foam is presented and compared to experimental results to assess the validity of a 3-D finite element model of the heat transfer and degradation processes. In this series of experiments, 320 kg/m3 PMDI foam in a 0.2 L sealed steel container is heated to 1,073 K at a rate of 150 K/min. The experiment ends when the can breaches due to the buildup of pressure. The temperature at key location is monitored as well as the internal pressure of the can. Both experimental uncertainty and computational uncertainty are examined and compared. The mean value method (MV) and Latin hypercube sampling (LHS) approach are used to propagate the uncertainty through the model. The results of the both the MV method and the LHS approach show that while the model generally can predict the temperature at given locations in the system, it is less successful at predicting the pressure response. Also, these two approaches for propagating uncertainty agree with each other, the importance of each input parameter on the simulation results is also investigated, showing that for the temperature response the conductivity of the steel container and the effective conductivity of the foam, are the most important parameters. For the pressure response, the activation energy, effective conductivity, and specific heat are most important. The comparison to experiments and the identification of the drivers of uncertainty allow for targeted development of the computational model and for definition of the experiments necessary to improve accuracy.

Determination of kinetic properties of polyurethane foam decomposition for pyrolysis modelling

A non-fire-retardant and a fire retardant polyurethane foam are tested under a nitrogen environment using thermogravimetry at different heating rates of 1, 5, 20 and 60 °C min−1 to obtain the foams’ decomposition behaviours. During decomposition, both foams experience two major mass loss reactions with the second reaction consuming most of the fuel. Three graphical techniques applied to calculate the kinetic properties governing each reaction are kinetic analysis, the Arrhenius plot method and the inflection point methods. In general, these methods are compatible with the pyrolysis model within Fire Dynamics Simulator Version 5 and Gpyro. A normalised version of the inflection point methods is also developed to improve the suitability of the kinetic properties with the simplest decomposition scheme of the pyrolysis model. A consistent trend is noted in the calculated kinetic properties of both foams regardless of the calculation techniques applied.

Influence of Pattern Coating Thickness on Porosity and Mechanical Properties of Lost Foam Casting of Al-Si (LM6) Alloy

The combination of Aluminum alloy with lost foam casting (LFC) process is best applied in automotive industry to replace steel components in order to achieve light weight components for reducing fuel consumption and to protect the environment. The LFC process involves process parameters such as the degree of vacuum, foam degradation, expanded polystyrene (EPS) foam density, permeability of foam pattern coatings, pouring temperature, filling velocity, cooling rate, and pressure. The effect of polystyrene foam pattern coating thickness on the porosity and mechanical properties of Aluminum Al-Si LM6 alloy were evaluated experimentally. The coating thickness was controlled by slurry viscosity at range between 18sec to 20sec using Zahn viscosity cup No.5 and the foam pattern was coated up to fifth layer. Aluminum Al-Si (LM6) molten metal was poured into expandable mould and castings were examined to determine porosity distribution, mechanical properties and microscopic observation. Results from X-ray testing reveal the porosity distribution on Aluminum Al-Si LM6 castings is greater at thicker foam pattern coating sample. Meanwhile, the tensile strength of casting decreases when foam pattern coating thickness increases. Microscope observation portray the present of porosity on the casting which shows more gas defects present at thicker foam pattern coating sample. The source of porosity in LFC process is due to air entrainment or the entraining gases from polystyrene foam decomposition during pouring of molten metal. As a conclusion, mechanical strength has inverse relationship with porosity.