Roadmap to Biodegradable Plastics—Current State and Research Needs
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SEARCH · Engineering Papers
Results for “plastic leakage”
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.
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Polydiketoenamines for a Circular Plastics Economy
The mismanagement and leakage of plastic waste into the environment are failures of modern society. Once in the environment, plastic waste degrades into microplastics on a time scale dependent on the resin chemistry and the associated biotic or abiotic process. Here, the high surface area of microplastics results in the contamination of ecosystems through the leaching of toxic chemicals compounded with plastics during manufacturing. In addition, the small size of microplastics increases the likelihood that they will be inhaled or ingested, which has led to the bioaccumulation of microplastics with documented harm. Furthermore, microplastics are more readily aerosolized and distributed by weather systems to areas remote from locations where plastic waste has been mismanaged. Consequently, the carbon cycle must now account for plastic waste discharge, degradation, and dispersal in the environment after the end of useful life on a global scale.
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Composite seal reduces alkaline battery leakage
Composite seal consisting of rubber or plastic washers and a metal washer reduces alkaline battery leakage. Adhesive is applied to each washer interface, and the washers are held together mechanically.
Clatterbuck, C. H.↗
Quantum chemically calculated Abraham parameters for quantifying and predicting polymer hydrophobicity
The leakage and accumulation of plastic in the environment is a significant and growing problem with numerous detrimental impacts and has led to a push toward the design and development of more environmentally benign materials. To this end, we have developed a quantum chemistry-based model for predicting the mobility of polymer materials from molecular structure. Hydrophobicity is used as a surrogate for mobility given that hydrophobic interactions drive much of the partitioning of contaminants in and out of various environmentally relevant compartments. To model polymer hydrophobicity, we adjusted a previously developed Quantum Chemically Calculated Abraham Parameter model to calculate Abraham parameters of small molecules from molecular structure information. The resulting model predicted the octanol-water partition coefficient (K OW ) of polymer repeating units with a root mean square error (RMSE) of 0.48 (log scale). Additionally, the hydrophobicity of high molecular weight polymer materials was captured through solubility parameters and Nile red staining experiments from the literature and predicted with RMSEs of 1.21 (J/cc) 0.5 and 3.42 nm, respectively. Finally, to test the environmental applicability of the model, the relative adsorption capacity of three polymers was predicted and used to unify sorption isotherms across multiple sorbates and polymer sorbents.
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DESIGN CRITERIA FOR ZERO-LEAKAGE CONNECTORS FOR LAUNCH VEHICLES. VOLUME I, SUMMARY, CONCLUSIONS, AND DESIGN EXAMPLES
Design criteria for zero-leakage connectors for launch vehicles - plastic flow & flange rolling
LAUNCH VEHICLE↗
Two-functional seal for hose connection
Seal, machined from a plastic material, prevents liquid hydrogen leakage from hose connectors. It serves as a block-type seal supporting maximum loading of the poppet with slight elastic deflection or as a lip-type seal that is deformed elastically in bending, tension, or compression by the seated poppet.
Richardson, M. B.↗
Nonspace technology resulting from the NASA FLUID connector programs
Leakage at static seals is a problem common to both NASA and industry. The subject of an intensive investigation has been the establishing of design criteria for reliable, low-weight, leak-tight fluid connectors. The problem has been broken into areas of investigation: the structure which supports the actual seal and the seal itself. A Separable Connector Design Handbook has been written to direct designers' efforts toward the optimum connector design for a given purpose. Included in this paper is a brief discussion of the topics covered in the Handbook, notable flanged connector design, threaded connector design, pressure energized seal design, leakage measurement techniques, and a catalog of current satisfactory seal configurations. Also included in this paper is a discussion of the principles of sealing, including the uses and characteristics of elastomers, plastics, and metals. The load-leakage characteristics of seals, the effect of internal pressure, the effect of surface finish on the leakage rate, the mode of material deformation under load, and the advantages of various seal configurations are discussed.
Sealing↗
Influence of facemask design on operational performance
Spirometric measurements of oxygen volume and determination of the amount of argon in exhaled breath are used to analyze facemask design efficiency during treadmill walking tests with subjects carrying plastic hoods filled with argon. Facemask leakage measurements established the better performance of a pneumatic seal type mask in comparison with plain seal type masks.
Griffin, O. G.↗
Dynamic captive plastic seal
Fluoroplastic material held captive between valve sealing surfaces of 16 to 125 rms microinches provides zero leakage to a high-pressure line at high cryogenic temperatures, when the plastic material is subjected to sufficient stress. This sealing technique makes unnecessary the use of superfinished valve sealing surfaces.
Dryer, E. O.↗
Electrostatic Spraying With Conductive Liquids
Thin, uniform polymer coatings applied in water base normally impossible to charge. Electrostatic sprayer modified so applies coatings suspended or dissolved in electrically conductive liquids. Nozzle and gun constructed of nonconductive molded plastic. Liquid passageway made long enough electrical leakage through it low. Coaxial hose for liquid built of polytetrafluoroethylene tube, insulating sleeve, and polyurethane jacket. Sprayer provided with insulated seal at gun-to-hose connection, nonconductive airhose, pressure tank electrically isolated from ground, and special nozzle electrode. Supply of atomizing air reduced so particle momentum controlled by electrostatic field more effectively. Developed to apply water-base polyurethane coating to woven, shaped polyester fabric. Coating provides pressure seal for fabric, which is part of spacesuit. Also useful for applying waterproof, decorative, or protective coatings to fabrics for use on Earth.
Kosmo, Joseph J.↗
Color film preservation system: Breadboard development
The development of an economically feasible system to prevent and/or substantially reduce the degradation of the color dyes of the retinal reflex images recorded on color slide films is discussed. Three different types of film storage systems were designed, fabricated, and tested. An extruded plastic cylindrical container was pressurized and no observable leakage occurred, indicating that long term storage is possible. An operational breadboard was fabricated. The system offers the capability to determine purging requirements to achieve various levels of oxygen concentration and precise leakage of various container configurations. The system has digitial display of oxygen content of the container, automatic control of the oxygen content as well as of the container to atmosphere pressure differential, and flow rate readout during purging.
Source record↗
1985 Nuclear Science Symposium, 32nd, and 1985 Symposium on Nuclear Power Systems, 17th, San Francisco, CA, October 23-25, 1985, Proceedings
The present conference ranges over topics in high energy physics instrumentation, detectors, nuclear medical applications, health physics and environmental monitoring, reactor instrumentation, nuclear spacecraft instrumentation, the 'Fastbus' data acquisition system, circuits and systems for nuclear research facilities, and the development status of nuclear power systems. Specific attention is given to CCD high precision detectors, a drift chamber preamplifier, a Cerenkov ring imaging detector, novel scintillation glasses and scintillating fibers, a modular multidrift vertex detector, radial wire drift chambers, liquid argon polarimeters, a multianode photomultiplier, the reliability of planar silicon detectors, the design and manufacture of wedge and strip anodes, ultrafast triode photodetectors, photomultiplier tubes, a barium fluoride plastic scintillator, a fine grained neutron hodoscope, the stability of low leakage silicon photodiodes for crystal calorimeters, and X-ray proportional counters. Also considered are positron emission tomography, single photon emission computed tomography, nuclear magnetic resonance imaging, Geiger-Muller detectors, nuclear plant safeguards, a 32-bit Fastbus computer, an advanced light water reactor, and nuclear plant maintenance.
Source record↗
Leak Stopper For Metal-To-Metal Tube Fittings
Plastic-coated steel device is conformal and strong. Washerlike seal stops leakage at Dynatube(TM) joints between metal tubes. Made to resist corrosion, seal aligns itself in joint for maximum effectiveness.
Trevathan, Joseph R.↗
An analysis of alternative technologies for the removal of ethylene from the CELSS biomass production chamber
A variety of technologies were analyzed for their potential to remove ethylene from the CELSS Biomass Production Chamber (BPC). During crop production (e.g., lettuce, wheat, soybean, potato) in the BPC ethylene can accumulate in the airspace and subsequently affect plant viability. The chief source of ethylene is the plants themselves which reside in plastic trays containing nutrient solution. The main sink for ethylene is chamber leakage. The removal technology can be employed when deleterious levels (e.g., 50 ppb for potato) of ethylene are exceeded in the BPC and perhaps to optimize the plant growth process once a better understanding is developed of the relationship between exogenous ethylene concentration and plant growth. The technologies examined were catalytic oxidation, molecular sieve, cryotrapping, permanganate absorption, and UV degradation. Upon analysis, permanganate was chosen as the most suitable method. Experimental data for ethylene removal by permanganate during potato production was analyzed in order to design a system for installation in the BPC air duct. In addition, an analysis of the impact on ethylene concentration in the BPC of integrating the Breadboard Scale Aerobic Bioreactor (BSAB) with the BPC was performed. The result indicates that this unit has no significant effect on the ethylene material balance as a source or sink.
Rakow, Allen L.↗
Compliant Turbomachine Sealing
Sealing interface materials and coatings are sacrificial, giving up their integrity for the benefit of the component. Seals that are compliant while still controlling leakage, dynamics, and coolant flows are sought to enhance turbomachine performance. Herein we investigate the leaf-seal configuration. While the leaf seal is classified as contacting, a ready modification using the leaf-housing arrangement in conjunction with an interface film rider (a bore seal, for example) provides for a film-riding noncontact seal. The leaf housing and leaf elements can be made from a variety of materials from plastic to ceramic. Four simplistic models are used to identify the physics essential to controlling leakage. Corroborated by CFD, these results provide design parameters for applications to within reasonable engineering certainty. Some potential improvements are proposed.
Hendricks, R. C.↗
Ultra-lightweight pressure vessels
Composite tanks fabricated from two metal spheres which are pressure welded and then overwrapped with plastic composite are 66 percent lighter than similar all-metal vessels. Overwrap minimizes shrapnel effects, shifts failure mode to that of cyclic leakage, and withstands minimum burst pressure.
Schmidt, W. W.↗
Water permeation and electrical properties of pottants, backings, and pottant/backing composites
It is reported that the interface between plastic film back covers and ethylene vinyl acetates (EVA) or polyvinyl butyral (PVB) in photovoltaic modules can influence water permeation, and electrial properties of the composites such as leakage current and dielectric constant. The interface can either be one of two dissimilar materials in physical contact with no intermixing, or the interface can constitute a thin zone which is an interphase of the two materials having a gradient composition from one material to the other. The former condition is described as a discrete interface. A discrete interface model was developed to predict water permeation, dielectric strength, and leakage current for EVA, ethylene methyl acrylate (EMA), and PVB coupled to Tedlar and mylar films. Experimental data was compared with predicted data.
Orehotsky, J.↗
[School-Based UV-B Monitoring Project in Support of EOS-CHEM]
This grant is an extension of Grant NAG5-8929 (Drexel Project Number 230026), resulting from extensions necessary to meet changing science objectives as described in the final report for NAG5-8929, a copy of which is attached. The instrument configuration resulting from NAG54929 has remained basically intact. Cosine response measurements conducted by James Slusser s group at Fort Collins, Colorado, in support of the proposal for Aura ground validation mentioned in the final report for NAG5-8929, indicated that there was significant light leakage to the detector through the sides of the nylon housing. This was easily remedied by machining a removable opaque collar (made from the dark same grey rigid plastic plumbing tubing as the collimating tube) that fits around the detector collar. Also during this grant period, data logging procedures were established for the UV-A instrument, to record irradiance before, during, and after an Aura overflight. This is required in order to compare spatial and temporal variability as required for ground validation of data products derived from the Ozone Monitoring Instrument (OMI). Standalone 12-bit loggers from Onset Computer Corporation (the U12 series), which were not available at the start of these projects, makes possible relatively inexpensive logging for these instruments at a usable resolution. configuration and disposition of these instruments, including the final version of a GLOBE protocol for using the instruments, currently depend on action taken on the Aura ground validation proposal submitted in 2004. A copy of that proposal is attached.
Brooks, David R.↗