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Durability of Polymeric Encapsulation Materials for Concentrating Photovoltaic Systems [Poster]

Description: Polymeric encapsulation materials are typically used in concentrating photovoltaic (CPV) modules to protect the cell from the field environment. Because it is physically located adjacent to the cell, the encapsulation is exposed to a high optical flux, often including light in the ultraviolet (UV) and infrared (IR) wavelengths. The durability of encapsulants used in CPV modules is critical to the technology, but is presently not well understood. This work seeks to identify the appropriate material types, field-induced failure mechanisms, and factors of influence (if possible) of polymeric encapsulation. These results will ultimately be weighed against those of future qualification and accelerated life test procedures.
Date: February 1, 2011
Creator: Miller, D. C.; Kempe, M. D.; Araki, K.; Kennedy, C. E. & Kurtz, S. R.
Partner: UNT Libraries Government Documents Department

Materials-based process tolerances for neutron generator encapsulation.

Description: Variations in the neutron generator encapsulation process can affect functionality. However, instead of following the historical path in which the effects of process variations are assessed directly through functional tests, this study examines how material properties key to generator functionality correlate with process variations. The results of this type of investigation will be applicable to all generators and can provide insight on the most profitable paths to process and material improvements. Surprisingly, the results at this point imply that the process is quite robust, and many of the current process tolerances are perhaps overly restrictive. The good news lies in the fact that our current process ensures reproducible material properties. The bad new lies in the fact that it would be difficult to solve functional problems by changes in the process.
Date: October 1, 2007
Creator: Berry, Ryan S.; Adolf, Douglas Brian & Stavig, Mark Edwin
Partner: UNT Libraries Government Documents Department

Plutonium Immobilization Can Loading Conceptual Design

Description: 'The Plutonium Immobilization Facility will encapsulate plutonium in ceramic pucks and seal the pucks inside welded cans. Remote equipment will place these cans in magazines and the magazines in a Defense Waste Processing Facility (DWPF) canister. The DWPF will fill the canister with glass for permanent storage. This report discusses the Plutonium Immobilization can loading conceptual design and includes a process block diagram, process description, preliminary equipment specifications, and several can loading issues. This report identifies loading pucks into cans and backfilling cans with helium as the top priority can loading development areas.'
Date: May 13, 1999
Creator: Kriikku, E.
Partner: UNT Libraries Government Documents Department

Activating Space within the Object and the Site

Description: I look at the world as a sculptor, examining physical constructs and implied meanings. My current research developed from my earlier studies of “containment” or, more specifically, “encapsulation,” creating visual, often physical, boundaries around selected content. Encapsulation confers a more active role than “containment”, a process rather than a result. This idea speaks to the issues of form, and asks the viewer to question the outside “shape of the form” in relation to the inside shape and content. My work focuses on exposed interior spaces and forms, allowing the viewer to enter the space physically as well as mentally and psychologically. Built in a large enough scale, the viewer could actually become the content. The sculpture’s interpretation revolves around the seen as well as the unseen. I built this duality into my work by using transparent and opaque materials. I also implemented small diameter stainless steel rod along with the transparent and opaque vinyl to reduce forms to their respective shapes and volumes. This approach allowed me to clean the “slate” of an object’s collective meaning and context, adapting it to the intent of my work.
Date: May 2001
Creator: Provence, Dana Noel
Partner: UNT Libraries

Reversible Guest Exchange Mechanisms in Supramolecular Host-Guest Assemblies

Description: Synthetic chemists have provided a wide array of supramolecular assemblies able to encapsulate guest molecules. The scope of this tutorial review focuses on supramolecular host molecules capable of reversibly encapsulating polyatomic guests. Much work has been done to determine the mechanism of guest encapsulation and guest release. This review covers common methods of monitoring and characterizing guest exchange such as NMR, UV-VIS, mass spectroscopy, electrochemistry, and calorimetry and also presents representative examples of guest exchange mechanisms. The guest exchange mechanisms of hemicarcerands, cucurbiturils, hydrogen-bonded assemblies, and metal-ligand assemblies are discussed. Special attention is given to systems which exhibit constrictive binding, a motif common in supramolecular guest exchange systems.
Date: September 1, 2006
Creator: Pluth, Michael D. & Raymond, Kenneth N.
Partner: UNT Libraries Government Documents Department

Simultaneously Bound Guests and Chiral Recognition: A Chiral Self-Assembled Supramolecular Host Encapsulates Hydrophobic Guests

Description: Driven by the hydrophobic effect, a water-soluble, chiral, self-assembled supramolecular host is able to encapsulate hydrophobic organic guests in aqueous solution. Small aromatics can be encapsulated in the supramolecular assembly, and the simultaneous encapsulation of multiple guests is observed in many cases. The molecular host assembly is able to recognize different substitutional isomers of disubstituted benzenes with ortho substitution leading to the encapsulation of two guests, but meta or para substitution leading to the encapsulation of only one guest. The scope of hydrophobic guest encapsulation is further explored with chiral natural product guests. Upon encapsulation of chiral guests into the racemic host, diastereomeric host-guest complexes are formed with observed diastereoselectivities of up to 78:22 in the case of fenchone.
Date: March 6, 2008
Creator: Hastings, Courtney J.; Pluth, Michael D.; Biros, Shannon M.; Bergman, Robert G. & Raymond, Kenneth N.
Partner: UNT Libraries Government Documents Department

Mold-filling experiments for validation of modeling encapsulation. Part 1, "wine glass" mold.

Description: The C6 project 'Encapsulation Processes' has been designed to obtain experimental measurements for discovery of phenomena critical to improving these processes, as well as data required in the verification and validation plan (Rao et al. 2001) for model validation of flow in progressively complex geometries. We have observed and recorded the flow of clear, Newtonian liquids and opaque, rheologically complex suspensions in two mold geometries. The first geometry is a simple wineglass geometry in a cylinder and is reported here in Part 1. The results in a more realistic encapsulation geometry are reported in Part 2.
Date: June 1, 2005
Creator: Castaneda, Jaime N.; Grillet, Anne Mary; Altobelli, Stephen A. (New Mexico Resonance, Albuquerque, NM); Cote, Raymond O. & Mondy, Lisa Ann
Partner: UNT Libraries Government Documents Department

Quantitative prediction of stresses during thermoset cure

Description: Two thin-walled Al tubes were filled with epoxy which were cured isothermally; one tube was instrumented with strain gauges, and the other with thermocouples. Finite element codes were used. Predicted and measured centerline hoop strains are shown; predictions and measurements agree. This is being applied to encapsulated components.
Date: July 1, 1996
Creator: Adolf, D.; Chambers, B. & Burchett, S.
Partner: UNT Libraries Government Documents Department

Development work on a new package design for the next generation microelectronics. Final report

Description: AlliedSignal and Micro-Mode Products joined under a DOE CRADA to develop a new package for next-generation electronics devices. Requirements included low cost of manufacture, ability to satisfy thermal expansion requirements, ability to satisfy thermal dissipation requirements, acceptable digital and microwave performance, and hermeticity. Four processes were tested; vacuum deposition of paralene, epoxy powder coating, transfer molding, and manual encapsulation. Transfer molding and manual potting improved the hermeticity but produced microcracking and reduced heat transfer ability following encapsulation. Additional study on manufacturing and encapsulating of the package is needed.
Date: November 1, 1996
Creator: Adams, B.E. & DeMarco, V.
Partner: UNT Libraries Government Documents Department

Measurement techniques for evaluating encapsulant thermophysical properties during cure

Description: Sandia now has the capability to evaluate stresses during cure of epoxies with finite element codes. Numerous material parameters are needed as input to these codes. I present a relatively quick set of tests which enable evaluation of the required thermophysical properties. Ease and accuracy of the tests improve as the reaction rate of the thermoset slows. Material parameters for common encapsulants at Sandia are presented in tables.
Date: June 1, 1996
Creator: Adolf, D.
Partner: UNT Libraries Government Documents Department

INOR-037: Encapsulation of hazardous metals with organic modified minerals

Description: The authors studies have focused on the development of new materials for the control, treatment, and long term storage of hazardous metals. The process involves the introduction of hazardous cations into the matrix of clays through aqueous ion-exchange methods. These cations are subsequently encapsulated within the clay by treating the material with a variety of organic silanes. This treatment results in the formation of organic coatings which are chemically bonded to the surface of the clay. The coatings are hydrophobic in nature, and may restrict the diffusion of water into and out of the pores contained within the clay. The goal of this process is to reduce the undesirable migration of hazardous metals from the ion-exchanged clays into the environment. A smectic type clay, bentonite, has been the primary inorganic matrix for this study. Bentonite, which is a form of montmorillonite, consists of two-dimensional sheets of aluminosilicates. Like other smectite clays, these sheets are separated by an interlayer which contains cations and water. The reactive groups within the alkyl silanes react with hydroxyl groups on the clay surface, as well as water contained on and within the clay. The authors results show that there is little difference in the metal content of the coated and noncoated clays. The cations are not removed from the clay by exposure to the silane. The clays also maintain their general structure and cystallinity upon surface modification. The organic coatings are stable to 500{degrees}C when heated under nitrogen. The ability of these systems to encapsulate the cations and prevent their migration into the environment is currently being evaluated.
Date: December 31, 1995
Creator: Song, Kang; Wasserman, R. & Yuchs, S.E.
Partner: UNT Libraries Government Documents Department

Epoxy Foam Encapsulants: Processing and Dielectric Characterization

Description: The dielectric performance of epoxy foams was investigated to determine if such materials might provide advantages over more standard polyurethane foams in the encapsulation of electronic assemblies. Comparisons of the dielectric characteristics of epoxy and urethane encapsulant foams found no significant differences between the two resin types and no significant difference between as-molded and machined foams. This study specifically evaluated the formulation and processing of epoxy foams using simple methylhydrosiloxanes as the flowing agent and compared the dielectric performance of those to urethane foams of similar density.
Date: January 1, 1999
Creator: Domeier, Linda & Hunter, Marion
Partner: UNT Libraries Government Documents Department

Mandrel development update

Description: We report on the progress since January, 1998, in preparing polymer mandrels by microencapsulation for NIF scale ICF capsules that meet the required symmetry and surface finish requirements. During that time we successfully completed our FY98 DOE TDF4.1 milestone of improving the mandrel low mode to meet NIF requirements. A number of batches of 2 mm microencapsulated poly(a- methylstyrene) shells have been produced with mode 2 out-of-rounds of less than 2 {micro}m. Detailed characterization for these and other batches is presented. We have found that the key to reducing mode 2 out-of-round is the density matching of the composite oil/inner core water microencapsulated shell preform to the supporting bath. Density matching of the inner core water to the oil phase seems to be less important, perhaps because core centering is accomplished by other physical means. Shell roughness over the very important mode 10 to 100 region is still too high by at least a decade in power, and work aimed at improving this is the task for FY99. In addition to basic sphericity results we also report on a number of experiments designed to elucidate the fundamental scientific issues. In most cases the experiments reported are but starting points that will be followed up during FY99. Lastly we note that no effort has been placed on optimizing the overcoating and thermal decomposition steps, which must follow the successful microencapsulation step. Based upon GA� s experience with smaller scale shells we are hopeful that these steps will not degrade capsule symmetry and surface finish. This question should be answered at least in part during FY99 as GA begins to supply finished 2 mm CH mandrels for the polyimide and Be ablator development work.
Date: February 1, 1999
Creator: Buckley, S; Cook, B; Hassel, A & Takagi, M
Partner: UNT Libraries Government Documents Department

Plutonium Immobilization Can Loading Equipment Review

Description: This report lists the operations required to complete the Can Loading steps on the Pu Immobilization Plant Flow Sheets and evaluates the equipment options to complete each operation. This report recommends the most appropriate equipment to support Plutonium Immobilization Can Loading operations.
Date: May 1998
Creator: Kriikku, E.; Ward, C.; Stokes, M.; Randall, B.; Steed, J.; Jones, R. et al.
Partner: UNT Libraries Government Documents Department

Plutonium Immobilization Can Loading Concepts

Description: The Plutonium Immobilization Facility will encapsulate plutonium in ceramic pucks and seal the pucks inside welded cans. Remote equipment will place these cans in magazines and the magazines in a Defense Waste Processing Facility (DWPF) canister. The DWPF will fill the canister with glass for permanent storage. This report discusses five can loading conceptual designs and the lists the advantages and disadvantages for each concept. This report identifies loading pucks into cans and backfilling cans with helium as the top priority can loading development areas. The can loading welder and cutter are very similar to the existing Savannah River Site (SRS) FB-Line bagless transfer welder and cutter and thus they are a low priority development item.
Date: May 1998
Creator: Kriikku, E.; Ward, C.; Stokes, M.; Randall, B.; Steed, J.; Jones, R. et al.
Partner: UNT Libraries Government Documents Department

Waste encapsulation storage facility (WESF) standards/requirements identification document (S/RIDS)

Description: This Standards/Requirements Identification Document (S/RID) sets forth the Environmental Safety and Health (ES{ampersand}H) standards/requirements for the Waste Encapsulation Storage Facility (WESF). This S/RID is applicable to the appropriate life cycle phases of design, construction, operation, and preparation for decommissioning. These standards/requirements are adequate to ensure the protection of the health and safety of workers, the public, and the environment.
Date: July 29, 1996
Creator: Maddox, B.S., Westinghouse Hanford
Partner: UNT Libraries Government Documents Department

Weapon foam accelerated aging using dynamic mechanical analysis

Description: Rigid polyurethane foams are used for supports and as encapsulants for electronic assemblies in almost all weapon systems. Mechanical properties (storage, loss, rubbery, and glassy moduli) of three foams are being evaluated; the test scheme is illustrated. Aging tests are also being run on the long-term performance of foams being used in the Russian Fissile Material Container; there was no significant change in the glass transition temperature, glassy modulus, or rubbery modulus after one year of aging.
Date: March 1, 1996
Creator: Rand, P.B. & Hance, B.G.
Partner: UNT Libraries Government Documents Department

External and Internal Guest Binding of a Highly Charged Supramolecular Host in Water: Deconvoluting the Very Different Thermodynamics

Description: NMR, UV-vis and isothermal titration calorimetry (ITC) measurements probe different aspects of competing host-guest equilibria as simple alkylammonium guest molecules interact with both the exterior (ion-association) and interior (encapsulation) of the [Ga{sub 4}L{sub 6}]{sup 12-} supramolecular assembly in water. Data obtained by each independent technique measure different components of the host-guest equilibria and only when analyzed together does a complete picture of the solution thermodynamics emerge. Striking differences between the internal and external guest binding are found. External binding is enthalpy driven and mainly due to attractive interactions between the guests and the exterior surface of the assembly while encapsulation is entropy driven as a result of desolvation and release of solvent molecules from the host cavity.
Date: July 22, 2009
Creator: Sgarlata, Carmelo; Mugridge, Jeffrey; Pluth, Michael; Tiedemann,, Bryan; Zito, Valeria; Arena, Giuseppe et al.
Partner: UNT Libraries Government Documents Department

Making Amines Strong Bases: Thermodynamic Stabilization ofProtonated Guests in a Highly-Charged Supramolecular Host

Description: A highly-charged, cavity-containing supramolecular assembly formed by metal-ligand interactions acts as a host to dramatically shift the effective basicity of encapsulated protonated amine guests. The scope of encapsulated protonated amine and phosphine guests shows size selectivity consistent with a constrained binding environment. Protonation of the encapsulated guests is confirmed by {sup 31}P NMR studies, mass spectrometry studies, and the pH dependence of guest encapsulation. Rates of guest self-exchange were measured using the Selective Inversion Recovery method and were found to correlate with the size rather than the basicity of the guests. The activation parameters for guest self-exchange are consistent with the established mechanism for guest exchange. The binding constants of the protonated amines are then used to calculate the effective basicity of the encapsulated amines. Depending on the nature of the guest, shifts in the effective basicities of the encapsulated amines of up to 4.5 pK{sub a} units are observed, signifying a substantial stabilization of the protonated form of the guest molecule and effectively making phosphines and amines strong bases.
Date: April 16, 2007
Creator: Pluth, Michael D.; Bergman, Robert G. & Raymond, Kenneth N.
Partner: UNT Libraries Government Documents Department

Electrical properties of REF308, REF320, EF-AR20, and RSF200 foam encapsulants.

Description: Foam encapsulants are used to encapsulate electromechanical assemblies for reasons such as shock mitigation, structural support, and voltage breakdown protection. Characterization of electrical properties of polymer encapsulants is important in situations where potting materials are in intimate contact with electrical components (e.g., printed wiring boards). REF308, REF320, RSF200, and EF-AR20 foams were developed for encapsulation in some potting applications at Sandia. Select electrical properties were measured for these Sandia encapsulants to characterize them for use in electromechanical potting applications. Dielectric constant with dissipation factors, volume resistivity, and dielectric strength were measured for REF308, REF320, RSF200, and EF-AR20 encapsulants. Fabrication of foam test specimens and the electrical test procedures will be discussed, and electrical testing results will be reported.
Date: January 1, 2006
Creator: Russick, Edward Mark
Partner: UNT Libraries Government Documents Department