Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “FILLER”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Effects of high-pressure hydrogen exposure on filler-elastomer adhesion

Elastomers are known to gain enhanced mechanical properties through compounding with nanosized filler particles such as silica or carbon black. Filler dispersion and filler-polymer interfacial strength are key contributing factors to this improvement. The interfacial strength is critical to part lifetime in pressurized gas sealing applications such as O-rings, where weak binding between the filler particle and polymer matrix can lead to internal void structures. With the aim to build a fundamental understanding of precursors to pressurized hydrogen-induced failure in elastomers, we use all-atom molecular dynamics simulations to study the impact of hydrogen oversaturation on filler-polymer interaction strength. We systematically study the interface between a commonly used elastomer, ethylene-propylene-diene monomer (EPDM) and silica by varying gas concentration, crosslink density, and surface chemistry. Our simulations predict that decompression leads to a localization of excess gas near the interface. In conclusion, we demonstrate that this localized gas can weaken interfacial adhesion and quantify the interaction using thermodynamic approaches.

EPDM↗
DOE OSTI2025

Impact of melt viscosity on filler dispersion in elastomeric nanocomposites

Compounding of commercial nanocomposites usually involves the addition of viscosity enhancers such as binder resins in ink jet inks, and paints. Contrary to this, plasticizers such as process oils are added to reduce the melt viscosity and ease processability of reinforced elastomers. Nanofillers such as silica and carbon black are typically added to reinforce rubber and enhance performance of automotive tire treads. Filler dispersion has traditionally been qualitatively (indirectly) assessed by measuring the properties of reinforced elastomers. While dispersion can be quantified by examining filler agglomeration through surface roughness measurements and microscopy, the size-scale dependence for these hierarchical fillers has usually been ignored. Here, we have recently devised a method to quantify nano-scale dispersion of fillers using Ultra small-angle X-ray scattering (USAXS) techniques. This method is advantageous since it directly links the controllable processing/compounding parameters such as the mixing speed, mixer geometry, residence time (or mixing duration), melt density, flow gap distance, and melt viscosity to nano-scale dispersion. While our previous studies have explored the impact of different processing parameters, this study specifically investigates the impact of melt viscosity on nano-scale filler dispersion in elastomer compounds. Commercially available polybutadienes with different Mooney viscosities were used in conjunction with different grades and amounts of process oils to modify the melt viscosity.

Carbon black↗
DOE OSTI2025

Enhancing Thermal Transport in Polymeric Composites Via Engineered Noncovalent Filler–Polymer Interactions

Understanding thermal transport mechanisms in polymeric composites allows us to expand the boundaries of thermal conductivity in them, either increasing it for more efficient heat dissipation or decreasing it for better thermal insulation. But, these mechanisms are not fully understood. Systematic experimental investigations remain limited. Practical strategies to tune the interfacial thermal resistance (ITR) between fillers and polymers and the thermal conductivity of composites remain elusive. Here, we studied the thermal transport in representative polymer composites, using polyethylene (PE) or polyaniline (PANI) as matrices and graphite as fillers. PANI, with aromatic rings in its backbone, interacts with graphite through strong noncovalent π–π stacking interactions, whereas PE lacks such interactions. We can then quantify how π–π stacking interactions between graphite and polymers enhance thermal transport in composites. PE/graphite and PANI/graphite composites with the same 1.5% filler volume fractions show a ∼22.82% and ∼34.85% enhancement in thermal conductivity compared to pure polymers, respectively. Calculated ITRs in PE/graphite and PANI/graphite are ~6 x 10 -8 m 2 KW -1 and ~1 x 10 -8 m 2 KW -1 , respectively, highlighting how π–π stacking interactions reduce ITR. Molecular dynamics (MD) simulations suggest that π–π stacking interactions between PANI chains and graphite surfaces enhance alignment of PANI's aromatic rings with graphite surfaces. This allows more carbon atoms from PANI chains to interact with graphite surfaces at a shorter distance compared to PE chains. Finally, our work indicates that tuning the π–π stacking interactions between polymers and fillers is an effective approach to reduce the ITR and enhance the thermal conductivity of composites.

atoms↗
DOE OSTI2023

ER4047 Filler Wire Development - Initial Studies

This report describes the results of bead on pipe welding trials for the purpose of evaluating commercial off the shelf (COTS) 0.047” ER4047 filler material vendors for down selection of the of best candidate filler material for future Gas-metal Arc Welding (GMAW) development efforts. Four candidate COTS ER4047 filler wires were evaluated during this work - Astrolite, Alcotec, Hobart, and Lincoln. The storage condition of each of these filler wires was documented and visual inspection was performed.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Compression Response of Silicone-Based Composites with Integrated Multifunctional Fillers

Polydimethylsiloxane (PDMS) is known for its exceptional mechanical properties, chemical stability, and flexibility. Recent advancements have focused on developing functional PDMS composites by integrating various functional fillers, including polymers, ceramics, and metals, for advanced applications such as electronics, medical devices, and aerospace. Consequently, there is a growing need to investigate PDMS composites to achieve higher filler loadings offering enhanced mechanical performance. This study addresses this need by utilizing the high molecular weight (MW) PDMS resin we have developed, offering its high elongation capacity of up to >6500%. We incorporated boron (B), hollow glass microballoons (HGMs), and tungsten-coated hollow glass microballoons (WHGMs) into the developed high MW PDMS. The resulting composites demonstrated excellent elastic properties and significant compression resilience (35–80%) and elastic modulus (1.28–10.15 MPa) at high filler loadings (~60 vol.%). Specifically, B/PDMS composites achieved up to 67.6 vol.% of B, HGM/PDMS composites held up to 68.6 vol.% of HGM, and WHGM/PDMS composites incorporated up to 54.0 vol.% of WHGM. These findings highlight the potential of high MW PDMS for developing high-performance PDMS composites suitable for advanced applications such as aerospace, automotive, and medical devices.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Advancements in active filler-contained polymer solid-state electrolytes for lithium-metal batteries: A concise review

Lithium-metal batteries (LMBs) usually are regarded as the pinnacle of next-generation energy storage due to the high specific capacity and low redox potential of the Li-metal anode. However, their development is hindered by safety hazards related to flammable electrolytes and uncontrolled side reactions within the battery. Both polymer and solid-state inorganic electrolytes, despite their potential, exhibit shortcomings that limit their practical applications. Active filler-containing polymer electrolytes (AFPEs) offer a promising solution by combining the benefits of both types. Enhanced by supramolecular interactions between the polymer matrix and active fillers, AFPEs demonstrate superior electrochemical performance over traditional polymer electrolytes. This review discusses the progress in active fillers and various polymer matrices, examining the factors that enhance performance, particularly ionic conductivity. It also outlines the future research directions of AFPEs, aiming to broaden the application of solid electrolytes in high-performance LMBs.

All solid-state batteries↗
DOE OSTI2025

Relationship Between Filler Type, Thermomechanical Properties, and Aging of RTV Silicone Foams

Room-temperature vulcanizing (RTV) silicone foams are used in many industrial applications that require the material to perform over long time periods. However, mechanical properties tend to deteriorate when these foams age under a compressive load. The chemical aging is attributed to the presence of unreacted functional groups of the prepolymers, residues from acid, and catalytically active tin (II) species. Here, an optimized thermal treatment of an RTV foam that achieves completion of curing reactions and deactivation of reactive species is proposed. Foams that were thermally aged for three months under compressive load showed no signs of compression set, indicative of the effectiveness of the implemented post-curing approach. In addition, the effects of fillers (diatomaceous earth, fumed silica, and carbon nanofibers) on thermomechanical properties were investigated. Tensile strength, tear strength, and thermal conductivity increased when these fillers were added to the unfilled RTV formulation, with carbon nanofibers (CNFs) being the most effective filler. Rheological studies of RTV formulations indicated that 2.5 wt.% of CNFs is the upper limit that can be added to the RTV formulation.

36 MATERIALS SCIENCE↗
DOE OSTI2024

In Situ Alloying Enabled by Active Liquid Metal Filler for Self‐Healing Composite Polymer Electrolytes

Abstract Solid inorganics, known for kinetically inhibiting polymer crystallization and enhancing ionic conductivity, have attracted significant attention in solid polymer electrolytes. However, current composite polymer electrolytes (CPEs) are still facing challenges in Li metal batteries, falling short of inhibiting severe dendritic growth and resulting in very limited cycling life. This study introduces Ga 62.5 In 21.5 Sn 16 (Galinstan) liquid metal (LM) as an active liquid alternative to conventional passive solid fillers, aiming at realizing self‐healing protection against dendrite problems. Compared to solid inorganics, for example silica, LM droplets could more significantly reduce polymer crystallinity and enhance Li‐ion conductivity due to their liquid nature, especially at temperatures below the polymer melting point. More importantly, LMs are unraveled as dynamic chemical traps, which are capable of blocking and consuming lithium dendrites upon contact via in situ alloying during battery operation and further inhibiting dendritic growth due to the lower deposition energy barrier of the formed Li‐LM alloy. As a proof of concept, by strategically designing an asymmetric CPE with the active LM filling, a solid‐state Li/LiFePO 4 battery achieves promising full‐cell functionality with notable rate performance and stable cycle life. This active filler‐mediated self‐healing approach could bring new insights into the battery design in versatile solid‐state systems.

Wu, Kai↗
DOE OSTI2025

Influence of functional additives, fillers, and pigments on thermal and catalytic pyrolysis of polyethylene for waste plastic upcycling

Pyrolysis offers a relatively green and economical method to convert waste plastics into valuable chemicals and fuels without the need for harmful solvents, toxic chemicals, or costly high-pressure reactors. Despite its popularity among chemical upcycling technologies, industrial adoption suffers from feedstock heterogeneity, low-quality products, and catalyst deactivation. Most plastics in our daily lives are formulated with functional additives, fillers, and colorants. These additives remaining in end-of-life waste streams increase feedstock heterogeneity, creating a challenging issue in recycling plastics. Still, the potential impacts of additives on the chemical upcycling of plastics have been poorly understood. In this study, polyethylene compounded with a range of widely used additives (antioxidants, stabilizers, pigments, fillers, slip agents, and flame retardants) was subjected to both thermal pyrolysis and catalytic pyrolysis in different catalyst-to-feedstock contact modes. It showed that many inorganic additives, such as talc, kaolin, CaCO 3 , TiO 2 , carbon black, and zinc stearate, facilitated polymer decomposition during pyrolysis, increasing light hydrocarbons while also promoting aromatic and carbon residue formation. Conversely, antioxidants and stabilizers inhibited depolymerization, favoring heavier hydrocarbons. During catalytic pyrolysis with HZSM-5 zeolite, additives strongly enhanced aromatic and catalytic coke formation, especially when there was direct contact between plastics and catalysts. Although certain additives seem beneficial in the short term by promoting polymer cracking and improving the selectivity of aromatics, the transport of the additives and their degradation products and increased carbon coking can contaminate products, deactivate or modify catalysts, and foul reactors. These findings address a critical knowledge gap in effectively converting waste plastics via a greener route.

42 ENGINEERING↗
DOE OSTI2024

Effects of Structure and Filler on Mechanical Properties of Direct Ink Write Pads

Direct ink write (DIW) is an extrusion-based additive manufacturing (AM) technique that enables superior repeatability, property tuning, and material customization compared to conventional manufacturing techniques. In this research, DIW is used to print silicone foams that must accommodate the thermal expansion of other parts. This expansion requires the material to compress and subsequently recover. Thus, a key performance metric is reducing “compression set” or deformation retained after the material is compressed. For this study, a silicone resin was compounded with a getter material, 1,4 bis(phenylethynyl)benzene (DEB) mixed with carbon-supported palladium (Pd) and printed in a variety of lattice structures. The effects of the filler and print structure on compression set were evaluated. In these experiments, 0.5-inch diameter coupons were compressed to 75% their original height for 22 hours at 70 °C, and the change in height calculated at intervals between 30 minutes and 24 hours post-decompression. The unfilled pad with skin layers had the best compression set at 0.7% ± 0.1%, followed by the unfilled pad with no skins at 1.5% ± 0.1%. As the number of filled layers increased, compression set performance degraded. The pad with filled skin layers and all filled layers had a compression set of 7.0% ± 0.3%. Additionally, the reaction extent of DEB was found to increase compression set, possibly due to the diffusion of DEB to the surface at elevated temperatures. Imaging reveals extensive crystallization at the surface. These investigations show that a non-reinforcing filler will increase compression set but that print structure can mitigate this effect.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Composite coatings from polycarbosilane derived SiC and Al/SiC cermet active fillers as protective barriers against steel corrosion

Stainless steel is used throughout the world as a structural material. However, it undergoes corrosion damage when exposed to extremely corrosive media, such as the marine environment. An alternative to solve this problem lies in the development of coatings that can withstand extreme conditions but also be easily deposited with inherently corrosion-resistant materials such as silicon carbide (SiC). The present study shows a simple method to produce Al/SiC cermet powders by attrition milling. The resulting cermet powders with a metallic matrix and hemispherical morphology, were employed as fillers in polycarbosilane (PCS) solutions that were sprayed on A304 stainless steel substrates. Al/SiC composite coatings were produced after heating the sprayed suspensions at 700 °C for 1 h in Ar atmosphere. The resulting composite coatings exhibited low surface energies (< 35 mN/m), water contact angles of 53°, and adhesion strength of up to 30 MPa. Finally, corrosion tests were performed in a cyclic corrosion test chamber, showing that these coatings effectively reduced the corrosion rate of stainless steel by 87%, reaching corrosion rate values of 0.007 g/cm 2 year.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Nonlocal Effect of Percolated Particle Networks on Viscoelasticity of Polymer–Filler Nanocomposites: A Mesoscale Simulation Study

With nanoparticles (NPs) as fillers, polymer nanocomposites (PNCs) usually exhibit enhanced mechanical properties. However, a direct connection between the microscopic structural relaxation and macroscopic mechanical properties of PNCs remains to be established. To investigate the micro-to-macro connection, we develop a mesoscale model, in which the NPbridging polymer chains are represented by a dynamic bonded interaction between NPs, and the bulk polymer matrix is implicitly modeled by overdamped Langevin dynamics. Extensive equilibrium simulations are performed to quantify the microscopic dynamics of model PNCs. Systematic analyses of modified Rouse dynamics, dynamic structure factor, and relaxation modulus uncover that the microscopic relaxation dynamics of PNCs are significantly decelerated across different length scales because of nonlocal effects of percolated particle networks a phenomenon that has not been adequately captured in prior simulation studies. We find that NPvolume- fraction and NP-bonding-energy barrier are the two critical variables that affect bulk viscoelasticity the most. The proposed mesoscale model is versatile and provides a powerful framework for studying structure−property relations of different PNCs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Effect of calcite filler on carbonation behavior in a synthesized C‐S‐H binder

Widespread implementation of portland limestone cements (PLC) in industry has raised new questions about their carbonation resistance due to higher initial limestone content than ordinary portland cement. While carbonation of portland cement and each of its hydrate phases has been studied at a fundamental level, the integral role of how limestone fillers interact chemically or physically during carbonation necessitates further study. In this study, a C-S-H binder comprised of a highly reactive zeolite pozzolan and lime was used to evaluate the effect of varying calcite additions on carbonation behavior at a microstructural level. Fundamental insight into hydration kinetics and carbonation mechanisms of hydraulic binders was obtained via analysis of the C-S-H and calcite microstructure. X-ray microcomputed tomography (X-ray CT) was used to quantify microstructural changes, and the results showed a decrease in shrinkage for increased calcite dosages, with a ∼50% reduction observed for a 45% wt. calcite replacement level. Crystallographic and thermal analyses measured compositional changes in the binder and confirmed that shrinkage was related to the decalcification of C-S-H. Furthermore, the addition of calcite to the C-S-H binder effectively reduced the liquid-to-solid ratio, porosity, and amount of C-S-H present in these binders. Ultimately, these results help elucidate how the carbonation risks of PLC can be mitigated by proportioning the mixture water only to the reactive component of the binder.

C-S-H↗
DOE OSTI2025

Mitigating Battery Cell Failure: Role of Ag‐Nanoparticle Fillers in Solid Electrolyte Dendrite Suppression

Abstract The development of solid‐state batteries (SSBs) with lithium Li metal anodes holds significant promise for enhancing the energy density and safety of next‐generation energy storage systems. However, their commercialization is hindered by challenges related to Li dendrite formation, which can lead to short circuits and battery failure. In this study, the role of Ag nanoparticles embedded within solid electrolytes (SE) is investigated in suppressing dendrite propagation. The results demonstrate that Ag nanoparticles effectively mitigate two key failure mechanisms: (1) dendrite growth within porous networks at low current densities and (2) stress intensification‐induced SE fracture at higher current densities (12 mA cm −2 ). Ex situ characterization using focused‐ion beam – scanning electron microscopy (FIB–SEM) and energy dispersive X‐ray spectroscopy (EDS,) reveals that Ag nanoparticles migrate alongside advancing Li dendrites, promoting homogeneous dendrite growth and reducing the likelihood of localized stress concentrations. Additionally, the incorporation of Ag nanoparticles is shown to facilitate a more uniform Li distribution toward the anode side, which can potentially enable the use of higher charging rates in SSBs. This study provides a new perspective on Li dendrite suppression and presents new opportunities for enhancing the performance and safety of SSBs.

Diallo, Mouhamad Said↗
DOE OSTI2024

Hybrid Composite Materials and Manufacturing: Fibers, Nano-Fillers and Integrated Additive Processes

This book explores the research and advancements in hybrid composite materials and manufacturing techniques. It encompasses a wide array of subjects, such as hybrid materials, advanced manufacturing processes, and nanocomposites. A distinctive feature of this book is its in-depth examination of recent trends in integrated processes, where traditional manufacturing methods are combined with cutting-edge techniques. Our aim is to equip readers with a comprehensive understanding of the current landscape and future potential of hybrid composites, ensuring they remain informed and up-to-date with the latest developments in the field.

Kumar, Vipin [ORNL] (ORCID:0000000295807098)↗