Low Burning Rate Research Articles

Electromagnetic interference shielding, mechanical, and flame retardant behaviors of Ti3C2Tx-MXene/glass fabric epoxy hybrid composites

This study investigates the manufacturability and electromagnetic shielding effectiveness (EMI-SE) of Ti3C2Tx/MXene-coated glass fabric laminated composites for aerospace applications. MXene-coated fabrics were produced using a dip-coating method. The effects of varying dipping counts (5 and 10) and different configurations of fabric arrangements on the EMI-SE of the composites in the X-band range (8.2–12.4 GHz) were investigated. Glass fabrics with 5 and 10 dips showed average surface resistances of 38.56 Ω/sq and 23.17 Ω/sq, respectively. In both the 5- and 10-dip composite sets, the total EMI-SE increased with the number of MXene-coated glass fabric layers in the composite. The 5MXC5 and 10MXC5 specimens, with conductive fabric in all layers, had average total shielding effectiveness (SET) of −18.75 dB and −23.21 dB, respectively. These values are 147.05 % and 205.80 % higher than the neat glass fiber-epoxy composite (C1). Flammability, bending, ILSS, and hardness tests were conducted on these composites. Increasing the MXene content reduced the burning rate, with 10MXC5 exhibiting a 26.31 % lower burning rate compared to C1. However, higher MXene content slightly decreased bending and ILSS values. Optical microscope examination of the fracture surfaces revealed that this decrease was due to delamination damage.

Flame Retardancy and Properties of Thermoplastic Vulcanizates from Dibutyl Phosphate-Bound Natural Rubber/Ethylene Vinyl Acetate Blends

ABSTRACT Dibutyl phosphate-bound epoxidized natural rubber (DBNR) was synthesized from natural rubber latex via epoxidation using a 20 mol% intermediate. Successful formation of epoxidized natural rubber (ENR-20) and DBNR was confirmed by FTIR analysis. Thermoplastic vulcanizates (TPVs) were prepared by dynamically vulcanizing blends of DBNR and ethylene-vinyl acetate copolymer (EVA). The 50/50 DBNR/EVA TPV exhibited higher mixing torque during vulcanization, indicative of increased shear stress, shear rate, and tensile strength. This was attributed to finer dispersion of vulcanized rubber domains in the EVA matrix, leading to enhanced interfacial adhesion. Elongation at break decreased with increasing EVA content, while hardness and tension set increased, suggesting reduced elasticity at higher EVA proportions. Under heat aging, TPVs experienced degradation of mechanical properties and increased tension set, indicating loss of elastomeric behavior. Significantly, DBNR exhibited a low burning rate of 0.2 mm/s, imparting inherent flame retardancy. The burning rate of DBNR/EVA TPVs decreased with increasing DBNR content, demonstrating improved flame retardancy. Overall, DBNR/EVA TPVs exhibited favorable mechanical properties and flame retardancy, making them suitable for applications requiring flame-retardant elastomeric materials.

Pengaruh Penambahan Butanol Pada Bahan Bakar Solar Terhadap Karakteristik Pembakaran Single Droplet

Dependence on fossil fuels is one of the most serious threats to the global environment. In addition, petroleum reserves are also decreasing. Meanwhile, the level of oil consumption is always increasing to meet the demand for fuel. Economical and sustainable alternative energy solutions are essential to meet the growing global energy demand without compromising environmental sustainability. One type of alternative fuel that shows very promising potential is biofuel, especially biodiesel. Biodiesel has potential as a more environmentally friendly alternative to diesel fuel, but its low combustion rate and higher viscosity compared to conventional diesel fuel present technical challenges that need to be overcome. The different chemical properties of butanol from biodiesel allow it to have a positive impact on combustion characteristics, such as viscosity, flash point, heating value, and combustion rate. The combustion characteristics that will be studied in this research using single droplet combustion testing include droplet visualization to measure the dimensions of the flame, temperature during the combustion process recorded by a thermocouple, data logger, and video recording during the combustion process to obtain information regarding the ignition delay value. The test steps were repeated five times for each fuel variation and then averaged. In this study, the samples tested included pure diesel, diesel blend with 10% butanol, diesel blend with 20% butanol, diesel blend with 30% butanol, diesel blend with 40% butanol and diesel blend with 50% butanol. From this study, the visualization of the flame is obtained, where the combustion of pure diesel oil droplets has a higher and wider flame, while the flame of the butanol diesel mixture produces a flame whose maximum height is lower than pure diesel oil. The ignition delay time of pure diesel oil is greater than the ignition delay time of the diesel butanol blend. In addition, the maximum combustion temperature produced by each blend is different

Hydroxyl‐terminated polybutadiene(HTPB) propellants cross‐linked by dimer acid diisocyanate (DDI): Cross‐linking network and properties

AbstractConsidering the high toxicity of toluene diisocyanate (TDI) and the low reactivity of isophorone diisocyanate (IPDI), a low‐toxicity curing agent, dimer acid diisocyanate (DDI), was used to cross‐link HTPB elastomers and propellants. The unique long‐chain structure of DDI not only ensures the elastic modulus and tensile strength of the elastomer, but also improves the flexibility to some extent. The long flexible chains promote the segment movement, which is very important for the formation of hydrogen bonds between segments. The chemical cross‐linking network and hydrogen bonding association play a significant role in the mechanical properties of the HTPB/DDI system. The relationship between the mole ratio of ‐NCO to ‐OH (R‐value) and the mechanical properties of HTPB/DDI elastomers were also investigated. In the range of R‐value from 0.85 to 1.2, the elastic modulus and tensile strength first increase and then decrease, and the elongation at break first decreases and then increases. Under the same curing conditions, the elastic modulus and tensile strength of the HTPB/DDI propellant are similar to the HTPB/TDI propellant. For the HTPB/AP/Al propellants and HTPB/AP/RDX/Al propellants, the HTPB/DDI system has lower burning rates in the range of 5–19 MPa than the HTPB/TDI system and HTPB/IPDI system. The application of DDI can reduce the burning rates of the propellant without adding any burning rate modifiers. It is considered that DDI can replace TDI and IPDI as a new curing agent with low toxicity and moderate reactivity for HTPB systems.

Enhancing mechanical and flame retardant characteristics of glass fiber-epoxy laminated composites through MXene and functionalized-MXene integration

MXene, a 2D transition metal carbide and nitride with graphene-like layered structures, has become one of the preferred choice for nano-reinforcement in polymer matrix composites in recent years due to its outstanding properties such as specific surface area, excellent thermal and mechanical characteristics, and high conductivity. In this study, the glass fiber-epoxy laminated composites reinforced with Ti3C2Tx-MXene (M)/ functionalized-MXene (FM) were produced using the hand lay-up procedure followed by vacuum bagging process. The effects of varying filler amounts (0.125, 0.25, 0.375, and 0.5%) on the mechanical and flame retardancy properties of glass fiber-epoxy composites were examined. In both M and FM reinforced composites, the highest values of mechanical strengths were obtained with a 0.25% filler, while a decrease in mechanical strengths was observed beyond this reinforcement amount. The 0.25 wt% FM-reinforced composite exhibited 19.21%, 27.55%, and 12.40% higher tensile, flexural, and interlaminar shear strengths (ILSS) than the pristine glass fiber-epoxy composite (N-C). Post-test analysis revealed the presence of matrix cracks, fiber breakage, and fiber pull-out damages were observed on the surfaces of composite samples. The flame retardant properties of the composites were enhanced with the addition of MXene reinforcement, and 0.5FM-C exhibited 25.50% lower burning rate than N-C.

Combustion performance modulation and agglomeration inhibition of HTPB propellants by fine Al/oxidizers integration

Modulation of burning rates and inhibition of aluminum agglomeration in solid propellants have generated considerable research interest in the field of energetic materials. In this paper, integrated Al/oxidizer composites have been prepared by a spray-drying technique, which offer intimate contact between the fuel and oxidizers. The morphologies, thermal stability, density, heats of explosion and combustion performance of the resulted solid propellants containing these Al-based composites were systematically investigated, where the condensed combustion products (CCPs) analysis and the agglomeration behavior of Al particles have been focused. After well control of the Al/oxidizers structure, 9 % higher explosion heat, 58 % higher pressurization rate and 65 % stronger flame radiation intensity were achieved in comparison to the conventional solid propellants with the same formulation. The burn rate of the propellants can also be well controlled by using different type of Al/oxidizers composites, in the range of 3.6–5.9 mm s−1 under 0.5 MPa and 9.2–10.9 mm s−1 under 15 MPa. More importantly, very low burn rate pressure exponent of 0.1 within 0.5–15 MPa was obtained. Inspired by decreasing size of CCPs, the evolution of Al on the burning surface was studied and the agglomeration inhibition was observed, whose potential mechanism was then proposed and elucidated.

The Effect of CuO on the Thermal Behavior and Combustion Features of Pyrotechnic Compositions with AN/MgAl

Ammonium nitrate (AN) is of considerable interest to researchers in developing new types of energetic mixtures due to the release of environmentally benign gaseous products during burning and thermal decomposition. However, poor ignition and a low burning rate require special additives to speed up this process. The advantage of this research is the use of high-energy aluminum-based alloys as fuel to compensate for the disadvantages of AN. In addition, the effect of copper oxide (CuO) on the burning kinetics and thermodynamics of the energetic mixture based on ammonium nitrate–magnesium–aluminum alloys (AN/MgAl) is investigated. Alloys based on aluminum were created through a process of high-temperature diffusion welding, conducted in an environment of argon gas. The structure and thermal characteristics of alloys are determined by X-ray diffraction, scanning electron microscopy, and DTA-TG analyses. It has been found that CuO has significant effects on the thermal decomposition of an AN/MgAl-based energetic mixture by shifting the decomposition temperature from 269.33 °C to 261.34 °C and decreasing the activation energy from 91.41 kJ mol−1 to 89.26 kJ mol−1. Adding CuO reduced the pressure deflagration limit from 2 MPa to 1 MPa, and the linear burning rate of the AN/MgAl energetic mixture increased approximately twice (rb = 6.17 mm/s vs. rb = 15.44 mm/s, at a chamber pressure of P0 = 5 MPa).

Numerical investigation on turbulent flame jet characteristics of a pre-chamber fueled with CH4/O2 and CH4/NH3/O2 mixture under different initial pressures

Ammonia is a very potential carbon-free alternative fuel with extremely low reactivity. The application of ammonia in internal combustion engines faces the risks of ignition failure, low burning rate, and poor combustion stability. Pre-chamber turbulent jet ignition (TJI), which can provide much more ignition energy, is a promising method to ignite ammonia fuel. However, the transient propagation process of pre-chamber jet flame has not been fully investigated yet. In this paper, the propagation characteristic of methane jet flame was numerically studied based on a constant volume combustion system. The supersonic jet flame propagation and Mach disk phenomenon were further analyzed with numerical methods. And the propagation characteristic of methane/ammonia mixed jet flame was investigated. According to the results, the formation and propagation process of methane jet flame has different characteristics at different stages. In High-speed development stage (Stage II) and Low-speed oscillation development stage (Stage III), the penetration distance of flame jet tip is almost proportional to the penetration time. However, the penetration speed of the two stages is significantly different. The change trend of the jet velocity at the outlet of orifice hole can also be divided into four stages: slow increasing, rapid increasing, gradual decreasing, and periodic oscillation. The periodic oscillation of the jet tip velocity and the jet velocity at the outlet of orifice hole is caused by the effect of forward and reverse shock waves. The calculation results of CH4/NH3/O2 mixture jet flame show that the addition of ammonia has significant effects on the flame propagation process in PC, the thermodynamic state of PC, and the propagation characteristics of jet flame. With the increase of ammonia proportion, the maximum pressure of PC gradually decreases and the pressure rise rate slows down. Meanwhile, the two-stage (the high-speed development stage and the low-speed development stage) characteristic of jet propagation process gradually disappears. And the addition of ammonia is more likely to destroy the two-stage characteristic under low initial pressure.

Effect of iron oxide on combustion and thermal decomposition of AN/MgAl-based pyrotechnic mixtures

Ammonium nitrate (AN) is widely used as an oxidizer in energetic-burning mixtures. However, poor ignition and low burning rate require special additives to speed up this process. MgAl alloy is used as a fuel to improve the burning characteristics of AN. Mg-50%Al Alloy was synthesized by a high-temperature diff usion bonding method. In addition, the eff ect of iron oxide on the burning characteristics of pyrotechnic mixtures was studied. The burning characteristics of pyrotechnic mixtures were determined by ignition in a high-pressure chamber. With the addition of iron oxide, the burning rate of pyrotechnic compounds increased up to two times. Also, the pressure defl agration limit of the pyrotechnic mixture was reduced from 2 MPa to 1 MPa. In addition, the thermal characteristics of pyrotechnic mixtures were studied, and activation energies were calculated.

Study on the Combustion Characteristics of Ethanol Nanofuel

This study investigates the thermophysical and combustion characteristics of ethanol-based nanofuels incorporating aluminum (Al) and nickel-coated aluminum (Ni-Al). The nanofuels are prepared with varying concentrations of Al and Ni-Al nanoparticles. The results reveal that, despite the non-uniform deposition of nickel on Al particles, a sintering reaction occurs between the two materials. Nanofuels containing Al exhibit unburned Al residues after combustion, while nanofuels containing Ni-Al show intense AlO radical emission during combustion termination, indicating enhanced combustion. However, nanofuels containing Ni-Al demonstrate a lower burning rate compared to Al nanofuels, attributed to the lower thermal conductivity of nickel. Overall, the findings suggest that nanofuels containing Ni-Al possess higher energy potential but extended combustion duration.

Energetic hydrogen-bonded open-framework as promising green combustion catalyst for nitramine-based solid propellants

The development of halogen-free nitramine-based green solid propellants has attracted a significant interest due to their application in rapidly developing aerospace technologies. However, relatively low burn rates, and generation of high pressure in the combustion chamber limit applications of such propellants. The alleviation of these problems could be achieved by using suitable combustion catalysts. Herein, a new energetic nitrogen-rich open framework compound 1 was prepared and evaluated as an efficient Pb-free combustion catalyst for HMX-nitrocellulose-nitroglycerin solid composite propellant formulation. Compound 1 was synthesized by a straightforward one-step process, its structure was comprehensively characterized by x-ray crystallography, and it was found to be thermostable (decomposition at 289 °C), insensitive to mechanical impact and friction (60 J, 360 N), and showed high hydrolytic stability. A propellant formulation containing 3.0 wt.% of 1 exhibited 45% increase in its burning rate (under 6.0 MPa) versus catalyst-free reference propellant. In the pressure range of 3–10 MPa, the pressure exponent was calculated to be 0.32, which is more than two times lower than of the reference propellant. These impressive properties of catalyst 1 suggest that it has a great potential to be further used in the development of future highly energetic green solid propellants.

Comparative analysis of ammonia/hydrogen fuel blends combustion in a high swirl gas turbine combustor with different cooling angles

In this study, numerical modeling of ammonia-hydrogen fuels (10%–50%) in a turbulent eddy gas turbine combustion chamber with different cooling angles (15, 30, 45) have been performed by using a computational fluid dynamics code. It has been observed that the maximum temperature levels in the combustion chamber decrease with the addition of ammonia and the flame moved towards the exhaust of the combustion chamber because of the lower burning rate of ammonia in the regions where the flame occurs. Although the addition of ammonia in the combustor increases the NOx levels in the flame core rapidly. The 45° provides a more homogeneous temperature distribution compared to other conditions with 15–30° inclination angles at the outlet. As a result, it can be concluded that ammonia-hydrogen blended fuels have a substantial possibility as an option and sustainable fuel in terms of combustion performance.

Effect of dielectric barrier discharge methane reforming products on the combustion performance of rocket engine

Although the low-thrust liquid oxygen/methane rocket engine has broad application prospects, the low flame propagation speed and low combustion rate of methane fuel make the liquid oxygen/methane engine still face key technical challenges. Methane fuel is partially converted into hydrogen and ethane with higher combustion rate before being injected into the combustion chamber, which is positive for the use of dielectric barrier to improve the combustion performance of the engine. Therefore, this paper studies the effect of the main four products of dielectric barrier discharge reforming with methane conversion rate of 10%, on the flow field of the combustion chamber. The results show that the addition of reforming products can effectively improve the combustion efficiency of the engine. H2 in the reforming product can also improve the specific impulse performance of the engine by increasing the total pressure of the engine chamber. C2H4 will not affect the maximum temperature of the engine, However, it can expand the medium-high temperature range of engine temperature to different degrees. The addition of H2 accelerates the oxygen consumption rate, which provides a feasible way to reduce the design size of the engine and improve the combustion efficiency of the low-thrust engine.

Unsaturated Polyester Resin/Aluminum Tri-hydroxide Added with Short Glass Fiber for Battery Box

A battery box made of polymer material must consider mechanical strengthand flame retardancy. One solution to increase the flame retardancy of polymers is toadd a flame retardant filler. However, sometimes adding a flame retardant filler cancause degradation of mechanical strength compared to neat polymers. The combinationof more than one type of filler or hybrid fillers can produce the optimal combination offlame retardancy and mechanical strength. An experimental study was carried out tocharacterize several composite polymer samples of unsaturated polyester (UP) resincombined with fillers of aluminum tri-hydroxide (ATH) to increase flame retardancyand short glass fiber (G) to improve mechanical strength. The DSC results show thatthe maximum endothermic of all samples occurred at a temperature of around 70 ºC.The TGA results prove that ATH and G can maintain the thermal stability of UP so thatthe composite samples were degraded at higher temperatures by reducing the rate ofweight degradation due to a temperature of around 0.1%/ºC. The burning test alsoshows that samples with ATH and G have a lower burning rate value than neat UP. Formechanical characterization, the tensile strength of the samples with ATH and G waslower than that of neat UP. However, UP/ATH/G2 showed an optimal compositioncompared to other filler compositions with a tensile strength of 41.5 MPa. This samplealso produces an optimal bending strength of 68.9 MPa and even higher than neat UP.These results were confirmed by SEM observations, in which filler G was exfoliated inthe UP. The broken G particles on the fracture surface observation prove the goodinterlock bonding between UP and G, which contributes to increasing the mechanicalstrength of the UP composite.

A novel multiple spark ignition strategy to achieve pure ammonia combustion in an optical spark-ignition engine

Ammonia is an attractive carbon-free fuel that has the potential to reduce the need for conventional hydrocarbons (HC) and reduce emissions of undesirable pollutants such as CO, CO2, particulates, and unburned hydrocarbons. However, ammonia has different combustion characteristics than conventional HC fuel. Ammonia is difficult to ignite and has a low combustion rate, resulting in large cyclic variations. In addition, nitrogen oxides (NOx) emissions in the exhaust tract are a major challenge when using ammonia as a fuel directly in engines. In this study, the effect of multiple spark ignition sites on the combustion of pure ammonia in an optical spark ignition engine (SI) was investigated. The experiment was conducted with four spark plugs mounted equidistantly on a special metal liner and one spark plug fitted at the top of the cylinder head. The multiple flames emitted from the different spark ignition sites were captured by natural flame luminosity (NFL) imaging. In the results, the conventional single spark ignition is compared with multiple ignitions. It was found that single spark ignition resulted in lower in-cylinder pressure, longer combustion duration, and higher combustion instability due to the poor ammonia fuel combustion rate. However, firing multiple spark plugs significantly improved combustion stability, increased engine power, and shortened the combustion period under the same operating conditions. In addition, the flame kernels produced by multiple ignition sites resulted in higher NOx emissions in the exhaust tract due to the higher temperatures in the cylinder. In addition, this study also investigated the effect of three different air–fuel equivalence ratios (λ) of 1.0, 1.2, and 1.4 on the combustion characteristics of ammonia fuel. The maximum NOx level was obtained for λ: 1.2 because the excess air in the mixture oxidizes the ammonia and provides abundant oxygen to generate more NOx. Further reducing the ammonia fuel and increasing the excess air to λ: 1.4 dramatically reduced NOx emissions due to the lower pressures and temperatures in the cylinder resulting from the longer combustion period.

Analysis of the Characteristics of Bio-Coal Briquettes from Agricultural and Coal Industry Waste

One of the options for reducing harmful emissions in the production of heat energy is the use of biomass, including in combination with industrial waste (for instance, coal and coke dust). Recent studies demonstrate that a mix of biomass and coal makes it possible to obtain a bio-coal briquette with better characteristics, which is a motivating factor in the search for alternative sources of heat energy from local agricultural waste. The aim of this research is to study the properties of bio-coal briquettes from biomass (sunflower husks and leaves) and industrial waste (coal and coke dust). The raw material was grinded and used for the production of bio-coal briquettes of 20%, 30%, 40%, 50%, 60%, and 70% of biomass. The biomass was grinded to the size of no more than 2 mm for the fine fraction and no more than 6 mm for the coarse fraction. The briquettes were made mechanically using a hydraulic press with a compression pressure of 25 MPa without the use of any binder. The characteristics of the investigated bio-coal briquettes, such as density, strength, moisture content, ash content, volatile yield, calorific value, ignition time, burning duration, and burning rate, have good enough values. The fine fraction briquettes compared to the coarse fraction briquettes have a longer burning time (about threefold longer) and a lower burning rate. For all briquettes, an increase in the composition of coal dust results in a rise in the burning time, whereas the burning rate falls. The best in terms of strength, calorific value and combustion parameters are the following briquettes: 70% sunflower husk and 30% coal dust from the Karazhyra deposit; 60% sunflower husk and 40% coal dust from the Shubarkul deposit; briquettes from 70% sunflower husk and 30% coke dust; briquettes from 80% leaves and 20% coal dust from the Karazhyra deposit; and briquettes from 70% leaves and 30% coal dust from the Shubarkul deposit. The selected briquettes are suitable as an alternative source of fuel.

Combustion model of a pyrolyzable polymer in a high-enthalpy flow with an radially applied electrostatic field

Polymers combustion in high-enthalpy flows is realized in many power plants. This process is energetically favorable, but there are also significant problems, the main of which is the low combustion rate. An effective method to increase the condensed component regression rate is the imposition of an electrostatic field on the polymer, the polymer reaction layer, and the combustion zone. The paper proposes a physical and mathematical model of the electrostatic field influence on the PMMA combustion rate in high-enthalpy flows. The combustion rate values calculated within the described model coincide with the experimental results within the error.

Catalytic performance of nano-sized cobalt copper ferrite on thermal decomposition of ammonium nitrate

Ammonium nitrate (AN) is being explored as a high energetic oxidizer in propellants. The utilization of pure AN in propellants suffers from a low burning rate. To improve the burning rate, it is important to improve the thermal decomposition characteristics of AN to fasten its thermal decomposition. The effect of CoCuFe2O4 additive was explored to improve the thermos-kinetic parameters of AN's thermal decomposition. Coprecipitation was used to synthesize nanocrystalline CoCuFe2O4. The thermodynamic and kinetic parameters of decomposition of AN: CoCuFe2O4 were investigated using TG-DSC-DTA analysis at 5, 10, and 15 °C min−1. The thermodynamic and kinetic studies suggest that the thermal decomposition of AN+CoCuFe2O4 was more favorable than AN. The decomposition of AN+CoCuFe2O4 occurs at a lower 10 °C lower temperature with ∼44 % decrement in the activation energy and decreased pre-exponential factor. The faster decomposition at a lower temperature was obtained for AN+CoCuFe2O4 composition. Nano-sized particles with efficient optical and polarizable properties made this ferrite material easily separable and eco-friendly for the preparation of a chemical propulsion system based on AN. The AN+CoCuFe2O4 propulsion mixture can be utilized in place of pure AN for better thermal performance in a propellant system.•CoCuFe2O4 was able to influence the thermal decomposition parameters of ammonium nitrate (AN).•AN+CoCuFe2O4 decomposes at lower activation energy with a faster decomposition than pure AN.•Thermodynamics suggest favorable decomposition of AN+CoCuFe2O4 than pure AN.

Enhanced combustion of ammonia engine based on novel air-assisted pre-chamber turbulent jet ignition

Ammonia has demonstrated great potential for achieving zero carbon emissions from internal combustion engines. However, the application of ammonia in engines faces the risks of ignition failure, low burning rate, and high nitrogen oxides emissions. Pre-chamber turbulent jet ignition (TJI) can provide multi-point ignition and fast combustion. Thus, in this study, a novel self-designed air-assisted pre-chamber apparatus is proposed to optimize the engine performance and combustion in a spark-ignition ammonia engine. The effects of high-reactivity pre-chamber fuels, including hydrogen, gasoline, and methane, on the performance of a TJI engine are investigated for the first time. The results show that, in the TJI mode considering the pre-chamber fueled with high-reactivity fuels, both the indicated mean effective pressure and indicated specific fuel consumption are improved compared with those in the spark-ignition mode. The enhanced combustion process involving shortened ignition delay and combustion duration is achieved by using the TJI mode. Double-peak phenomena are observed in both the pressure and heat release rate curves. In the TJI mode with the pre-chamber fueled with hydrogen, an optimal engine performance involving a high indicated mean effective pressure, low fuel consumption, and low coefficient of indicated mean effective pressure variation is obtained. Moreover, both peaks of the heat release rate are higher, and the ignition delay and combustion duration are further shortened owing to the jet effect produced by hydrogen combustion in the pre-chamber. Low NOx and NH3 emissions are observed in the TJI mode, particularly when the pre-chamber is fueled with hydrogen.

Methods of Preparation and Performance Evaluation of ABS/Mineral Microsphere Composites Produced through FDM and Compression Molding.

The use of amorphous microspheres as filler in composites is promising due to their light weight, low cost, incombustibility, and the ability to alter relevant properties of the final composite. Contrary to glass spheres, perlite microspheres are much cheaper and can be tailor-made to facilitate purpose-oriented alteration of the final composite. We report the use of perlite microspheres for the preparation of: (1) composites, through a compression molding (hot pressing) technique; and (2) composite filaments, in a single screw extruder, as well as their use for sample printing through Fused Deposition Modeling (FDM). Proper characterization of the produced composites allows for their evaluation in terms of physical, thermal, and mechanical properties and with regards to the manufacturing technique, the filler fraction, and size. Composite samples of acceptable quality in terms of filler survival and dispersion as well as mechanical properties were produced through compression molding using fine expanded perlite microspheres (<90 μm) up to an infill ratio of 40 vol.%. Fine fillers (<90 μm) performed well in FDM, allowing printing of composite dogbone samples with a higher Young’s modulus and elongation and similar ultimate tensile strength compared to benchmark, up to an infill ratio of 20 vol.%. Composite samples present a slightly lower burning rate compared to those produced solely by ABS. Perlite microspheres present good workability in both applications, possessing satisfactory performance as filler in the composites, and can thus be assumed a promising multifunctional filler for various thermoplastics considering their low price, environmental impact, and fire rating.