Materials

Water-Based Pressure-Sensitive Paints

Toxicity, and thus costs of ventilation and cleanup, is substantially reduced. Water-based pressure-sensitive paints (PSPs) have been invented as alternatives conventional organic- solvent-based pressure-sensitive paints, which are used primarily for indicating distributions of air pressure on wind-tunnel models. Typically, PSPs are sprayed onto aerodynamic models after they have been mounted in wind tunnels. When conventional organic- solvent- based PSPs are used, this practice creates a problem of removing toxic fumes from inside the wind tunnels. The use of water-based PSPs eliminates this problem. The water-based PSPs offer high performance as pressure indicators, plus all the advantages of common water-based paints low toxicity, low concentrations of volatile organic compounds, and easy cleanup by use of water).

Posted in: Materials, Briefs, TSP

Read More >>

Selective Plasma Deposition of Fluorocarbon Films on SAMs

The fluorocarbon films are useful as etch masks and perhaps as dielectric layers. A dry plasma process has been demonstrated to be useful for the selective modification of self-assembled monolayers (SAMs) of alkanethiolates. These SAMs are used, during the fabrication of semiconductor electronic devices, as etch masks on gold layers that are destined to be patterned and incorporated into the devices. The selective modification involves the formation of fluorocarbon films that render the SAMs more effective in protecting the masked areas of the gold against etching by a potassium iodide KI) solution. This modification can be utilized, not only in the fabrication of single electronic devices but also in the fabrication of integrated circuits, microelectromechanical systems, and circuit boards.

Posted in: Materials, Briefs

Read More >>

Ion-Exclusion Chromatography for Analyzing Organics in Water

Resolution of nonvolatile organic compounds is increased significantly. A liquid-chromatography technique has been developed for use in the quantitative analysis of urea (and of other nonvolatile organic compounds typically found with urea) dissolved in water. The technique involves the use of a column that contains an ion- exclusion resin; heretofore, this column has been sold for use in analyzing mono- saccharides and food softeners, but not for analyzing water supplies.

Posted in: Materials, Briefs

Read More >>

Making Plant-Support Structures From Waste Plant Fiber

Environmentally benign, biodegradable structures for supporting growing plants can be made in a process based on recycling of such waste plant fiber materials as wheat straw or of such derivative materials as paper and cardboard. Examples of structures that can be made in this way include plant plugs, pots, planter-lining mats, plant fences, and root and shoot barriers. No chemical binders are used in the process. First, the plant material is chopped into smaller particles. The particles are leached with water or steam to remove material that can inhibit plant growth, yielding a fibrous slurry. If the desired structures are plugs or sheets, then the slurry is formed into the desired shapes in a pulp molding subprocess. If the desired structures are root and shoot barriers, pots, or fences, then the slurry is compression-molded to the desired shapes in a heated press. The processed materials in these structures have properties similar to those of commercial pressboard, but unlike pressboard, these materials contain no additives. These structures have been found to withstand one growth cycle, even when wet.

Posted in: Materials, Briefs

Read More >>

Polyimides From a-BPDA and Aromatic Diamines

These polyimides have low color and high mechanical properties. Polymers having low color and a favorable combination of other properties, including high glass-transition temperature (Tg) and high mechanical properties (strength, tensile modulus, and toughness) will find use in a variety of terrestrial and space applications. Some of the space applications will be in thin films used as membranes on antennas, solar concentrators, coatings on second-surface mirrors, solar sails, sunshades, thermal and optical coatings, and multi-layer thermal insulation blankets. Depending upon the application, the film will be required to exhibit a unique combination of such properties as resistance to degradation by ultraviolet light, visible light, and electrons; low color and/or low solar absorptivity; resistance to tearing and/or wrinkling during packaging and deployment; and high mechanical properties (e.g. high strength, stiffness, and toughness). Recently developed polyimides having several of these desired properties are described below.

Posted in: Materials, Briefs

Read More >>

Generating Aromatics From CO2 on Mars or Natural Gas on Earth

The terrestrial version may make it economical to recover some natural-gas deposits. “Methane to aromatics on Mars” (“METAMARS”) is the name of a process originally intended as a means of converting Martian atmospheric carbon dioxide to aromatic hydrocarbons and oxygen, which would be used as propellants for spacecraft to return to Earth. The process has been demonstrated on Earth on a laboratory scale. A truncated version of the process could be used on Earth to convert natural gas to aromatic hydrocarbon liquids. The greater (relative to natural gas) density of aromatic hydrocarbon liquids makes it more economically feasible to ship them to distant markets. Hence, this process makes it feasible to exploit some reserves of natural gas that, heretofore, have been considered as being “stranded” too far from markets to be of economic value.

Posted in: Materials, Briefs

Read More >>

Cleaning Carbon Nanotubes by Use of Mild Oxygen Plasmas

Mildness of the plasmas is the key to cleaning without destruction. Experiments have shown that it is feasible to use oxygen radicals (specifically, monatomic oxygen) from mild oxygen plasmas to remove organic contaminants and chemical fabrication residues from the surfaces of carbon nanotubes (CNTs) and metal/CNT interfaces. A capability for such cleaning is essential to the manufacture of reproducible CNT-based electronic devices.

Posted in: Materials, Briefs, TSP

Read More >>