Functionalized Silk Materials

T he goal of this work was to exploit the novel structural, physical, and biological features of silk proteins towards functionalization of materials systems generated from this family of protein. A new generation of functional silk systems is sought to provide novel materials with precise control of material features. Three main directions were planned: (a) protein chimeras to form organic (silk) – inorganic nanocomposites; (b) formation of electronic materials using a similar design strategy, but based on enzymatic coupling reactions to form conducting polymers; and (c) continuing to understand and exploit novel processing approaches with these proteins towards new functional materials systems.

Posted in: Briefs, Materials, Research and development, Fabrication, Biomaterials, Materials properties

Dynamic Response and Failure Mechanisms of Layered Ceramic-Elastomer-Polymer/Metal Composites

A thorough study through a combination of ballistic and impact experiments, microscopic failure characterization, and numerical simulations has been carried out in order to decipher the underlying mechanisms involved in the interaction between a blast and/or a blast-induced high-velocity projectile and advanced ceramic-polymer and metal-polymer composites, resulting in an improved ballistic efficiency and impact- and blast-resistant structural system.

Posted in: Briefs, Materials, Ceramics, Composite materials, Elastomers, Metals, Protective equipment, Military vehicles and equipment

Fire Resistance of Geopolymer Concretes

Geopolymer concrete has been proposed as an alternative to Portland cement concrete in applications requiring high degrees of fire resistance, because the intrinsic chemistry of the geopolymer binder does not require the retention of water or hydration within gel phases to maintain structural integrity of the binder. Portland cement concrete contains a high level of chemically bound water, which is essential to the gel binder structure, and which is lost upon heating to several hundred degrees Celsius, whereas the water present within a geopolymer concrete is overwhelmingly present in pores and is not an essential part of the strength-generating phases. However, predictions of geopolymer concrete fire performance have up to this time been based on small-scale laboratory testing (usually on paste or mortar specimens), rather than the study of large concrete sections, which provides significance to this work.

Posted in: Briefs, Materials, Composite materials, Heat resistant materials, Polymers, Fire

Tomographic Electrical Resistance-Based Damage Sensing in Nano-Engineered Composite Structures

Advanced composite materials are increasingly replacing metals in the aerospace industry as they offer weight-saving improvements such as high specific strength and stiffness, while providing resistance to fatigue and corrosion. Traditional advanced composites, however, exhibit significantly reduced electrical and thermal conductivity relative to metals, and matrix-rich regions at ply interfaces result in relatively poor interlaminar properties. Additionally, composites that have sustained damage often have non-visible or barely visible damage, complicating damage assessment. Recent efforts to address the limitations of advanced composites include the incorporation of carbon nanotubes (CNTs) to take advantage of intrinsic and scale-dependent properties of these nanostructures.

Posted in: Briefs, Materials, Aircraft structures, Composite materials, Conductivity, Nanomaterials

Polymer Coating Material Limits Computer Damage Caused by Vibrations

Cornerstone Research Group (Dayton, OH) has developed an organic, polymer-based material that can be directly applied to any circuit board — as well as other metal- and plastic-based objects — to protect against vibrations.

Posted in: Tech Transfer Reports, Coatings & Adhesives

Real-Time Intelligent Chemical and Biological Nanosensors on a Flexible Platform

The objectives of this research are to examine the feasibility of real-time sensing of chemical and biological species by using the unique materials and electronic properties of carbon nanotubes, and to demonstrate the multi-agent sensing and information processing capabilities of such devices.

Posted in: Briefs, Materials, Sensors and actuators, Biomaterials, Chemicals, Nanotechnology

Templated Synthesis of Aluminum Nanoparticles for Stable Energetic Materials

Reactive nanoparticles as energetic materials have received much recent attention for a variety of existing and/or potential applications. Among more extensively investigated are nanosized (sub-100-nm) aluminum (Al) particles. Their large specific surface area and energy density, when coupled or mixed with oxidative species, make them unique combustible additives in propellant formulations. Nanoscale Al particles are also studied as high-capacity hydrogen storage materials. Therefore, significant effort has been made in the development of synthetic methodologies for Al nanoparticles of desired properties.

Posted in: Briefs, Materials, Hydrogen storage, Propellants, Fabrication, Aluminum, Nanomaterials

Performance Evaluation of Commercial Carbon Monofluoride Materials in Lithium Batteries

The performance of six different commercially available carbon monofluoride (CFx) materials was evaluated at four different discharge rates. The physical and chemical properties of the CFx materials were correlated to cell performance in lithium coin cells. This study was undertaken to determine how the physical and chemical properties of commercial CFx materials affect discharge capacity, discharge voltage, rate capability, and voltage delay in Li-CFx cells.

Posted in: Briefs, Materials, Lithium-ion batteries, Performance tests, Test procedures

Nanodomain Model of Polymer-Derived Ceramics

Areport discusses a model developed to explain the unusual properties of polymer- derived ceramics (PDCs), which are so named because they are made by controlled pyrolysis of cross-linked polymers. PDCs are metastable ceramics that have potential to be further developed into high-temperature materials that can be tailored to have properties needed to perform specific functions. The PDCs studied thus far have comprised silicon, carbon, nitrogen, and oxygen. The unusual properties of PDCs are the following: They bear similarity to both polymers and metallic glasses, even though the pyrolysis temperatures used in producing them are with experimental data.

Posted in: Briefs, Materials, Simulation and modeling, Ceramics, Heat resistant materials, Materials properties, Polymers

Characterization of High-Temperature Polymer Thin Films for Power Conditioning Capacitors

Wide bandgap semiconductors (e.g., silicon carbide) will enable operation of military systems at temperatures above 150 °C, which eases thermal management. However, such systems cannot be designed efficiently unless capacitors are available that can operate at similarly high temperatures.

Posted in: Briefs, Materials, Capacitors, Heat resistant materials, Polymers, Semiconductors, Military vehicles and equipment