Materials & Coatings

Extended Shelf Life for PMR Polyimide Resins and Prepregs

Secondary alcohols are used in place of primary alcohols.

An improved class of formulations for PMR polyimide resins retards the imidization that undesirably occurs during handling and storage. While imidization is desired at the final (deliberate polymerization) stage of production of a polyimide, imidization results in premature aging when it occurs during earlier stages of synthesis, shipping, prepregging, and fabrication layup. By retarding imidization at storage and handling temperatures, the improved class of formulations increases both shelf life and the upper limit of allowable temperature for handling and storage prior to final polymerization.

Posted in: Briefs, TSP, Materials, Performance upgrades, Storage, Resins, Durability, Durability

Silica-Filled EPDM Rubbers as Ablative Insulating Materials

These materials are intended to replace other materials that will soon be unavailable.

Silica-filled polymers made from ethylene propylene diene monomer (EPDM) have been found to be useful as ablative thermal-insulation materials. These polymers have been investigated as candidates to replace some previously developed polymeric ablative rocket-engine insulating materials that will soon become commercially unavailable. Although these materials have been developed specifically for use in and on solid-fuel rocket motors, they may also be useful in terrestrial applications in which there are requirements for protection against high temperatures for short times.

Posted in: Briefs, Materials, Elastomers, Heat resistant materials, Insulation, Rocket engines

Statistical Sampling of Tide Heights Study

The goal of the study was to determine if it was possible to reduce the cost of verifying computational models of tidal waves and currents. Statistical techniques were used to determine the least number of samples required, in a given situation, to remain statistically significant, and thereby reduce overall project costs. Commercial, academic, and Federal agencies could benefit by applying these techniques, without the need to “touch” every item in the population. For example, the requirement of this project was to measure the heights and times of high and low tides at 8,000 locations for verification of computational models of tidal waves and currents. The application of the statistical techniques began with observations to determine the correctness of submitted measurement data, followed by some assumptions based on the observations.

Posted in: Briefs, Materials, Computational fluid dynamics, Mathematical models, Statistical analysis, Water, Marine vehicles and equipment

Advanced Liquid-Cooling Garment Using Highly Thermally Conductive Sheets

This garment provides metabolic heat rejection applicable to surgical cooling vests, combat fatigues, and firefighter and hazmat suits.

This design of the liquid-cooling garment for NASA spacesuits allows the suit to remove metabolic heat from the human body more effectively, thereby increasing comfort and performance while reducing system mass. The garment is also more flexible, with fewer restrictions on body motion, and more effectively transfers thermal energy from the crewmember’s body to the external cooling unit. This improves the garment’s performance in terms of the maximum environment temperature in which it can keep a crewmember comfortable.

Posted in: Briefs, MDB, TSP, Briefs, TSP, Coatings & Adhesives, Materials, Bio-Medical, Medical, Human factors, Thermal management, Thermal management, Spacesuits

High-Speed Vision Inspection for Sheet-Based Electronics Materials

Process Photonics (Ottawa, ON, Canada) builds processing systems for the PCB, electronics assembly, and medical device markets. Their ProVisionTM series is a solution that uses vision to inspect panel and sheet-based circuit features. The system concept was devised after a customer expressed interest in replacing multiple existing inspection machines. The customer wanted a unit that was capable of significantly higher resolution and throughput, but also wanted to plan for a system that could perform defect recognition tasks beyond the original system’s capabilities.

Posted in: Application Briefs, Electronics, Materials, Electronic equipment, Imaging, Imaging and visualization, Optics, Electronic equipment, Imaging, Imaging and visualization, Optics, Automation, Quality control, Quality control, Inspections

Detecting Airborne Mercury by Use of Polymer/Carbon Films

These films can be operated and regenerated at mild temperatures.

Films made of certain polymer/carbon composites have been found to be potentially useful as sensing films for detecting airborne elemental mercury at concentrations on the order of tens of parts per billion or more. That is to say, when the polymer/carbon composite films are exposed to air containing mercury vapor, their electrical resistances decrease by measurable amounts. Because airborne mercury is a health hazard, it is desirable to detect it with great sensitivity, especially in enclosed environments in which there is a risk of a mercury leak from lamps or other equipment.

Posted in: Briefs, Materials, Chemicals, Composite materials, Polymers, Hazardous materials, Test equipment and instrumentation

Composite Silica Aerogels Opacified With Titania

Thermal insulation is enhanced by reducing the radiative contribution to heat transfer.

A further improvement has been made to reduce the high-temperature thermal conductivities of the aerogel-matrix composite materials described in “Improved Silica Aerogel Composite Materials” (NPO-44287), NASA Tech Briefs, Vol. 32, No. 9 (September 2008), page 50. Because the contribution of infrared radiation to heat transfer increases sharply with temperature, the effective high-temperature thermal conductivity of a thermal-insulation material can be reduced by opacifying the material to reduce the radiative contribution. Therefore, the essence of the present improvement is to add an opacifying constituent material (specifically, TiO2 powder) to the aerogel-matrix composites.

Posted in: Briefs, TSP, Materials

Multiplexed Colorimetric Solid-Phase Extraction

This analytical platform enables simultaneous determination of trace analytes in water.

Multiplexed colorimetric solid-phase extraction (MC-SPE) is an extension of colorimetric solid-phase extraction (CSPE) — an analytical platform that combines colorimetric reagents, solid phase extraction, and diffuse reflectance spectroscopy to quantify trace analytes in water. In C-SPE, analytes are extracted and complexed on the surface of an extraction membrane impregnated with a colorimetric reagent. The analytes are then quantified directly on the membrane surface using a hand-held diffuse reflectance spectrophotometer. Importantly, the use of solid-phase extraction membranes as the matrix for impregnation of the colorimetric reagents creates a concentration factor that enables the detection of low concentrations of analytes in small sample volumes.

Posted in: Briefs, Materials

Graphite Non-Wovens as Functional Layers in Diagnostic Test Kits

Blood-handling diagnostic test strips can be used for diabetes testing and monitoring, and testing for other diseases.

The separation of serum or plasma from whole blood is of overriding importance in clinical chemistry. In particular, many diagnostic detection reactions of blood components proceed without impairment only after the red blood corpuscles have been separated off. This particularly applies to color reactions that are evaluated either by reflectometry or visually, or also electrochemically.

Posted in: Briefs, MDB, Briefs, Coatings & Adhesives, Materials, Bio-Medical, Medical, Patient Monitoring, Fluids and secretions, Medical equipment and supplies, Graphite, Test equipment and instrumentation

Using Ozone To Clean and Passivate Oxygen-Handling Hardware

A proposed method of cleaning, passivating, and verifying the cleanliness of oxygen-handling hardware would extend the established art of cleaning by use of ozone. As used here, “cleaning” signifies ridding all exposed surfaces of combustible (in particular, carbon-based) contaminants. The method calls for exposing the surfaces of the hardware to ozone while monitoring the ozone effluent for carbon dioxide. The ozone would passivate the hardware while oxidizing carbon-based residues, converting the carbon in them to carbon dioxide. The exposure to ozone would be continued until no more carbon dioxide was detected, signifying that cleaning and passivation were complete.

Posted in: Briefs, Materials, Carbon dioxide, Oxygen equipment, Oxygen equipment, Hardware

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