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Sample records for polymers theory manufacturing

  1. Breaking Barriers in Polymer Additive Manufacturing

    SciTech Connect

    Love, Lonnie J; Duty, Chad E; Post, Brian K; Lind, Randall F; Lloyd, Peter D; Kunc, Vlastimil; Peter, William H; Blue, Craig A

    2015-01-01

    Additive Manufacturing (AM) enables the creation of complex structures directly from a computer-aided design (CAD). There are limitations that prevent the technology from realizing its full potential. AM has been criticized for being slow and expensive with limited build size. Oak Ridge National Laboratory (ORNL) has developed a large scale AM system that improves upon each of these areas by more than an order of magnitude. The Big Area Additive Manufacturing (BAAM) system directly converts low cost pellets into a large, three-dimensional part at a rate exceeding 25 kg/h. By breaking these traditional barriers, it is possible for polymer AM to penetrate new manufacturing markets.

  2. Additive manufacturing of polymer-derived ceramics.

    PubMed

    Eckel, Zak C; Zhou, Chaoyin; Martin, John H; Jacobsen, Alan J; Carter, William B; Schaedler, Tobias A

    2016-01-01

    The extremely high melting point of many ceramics adds challenges to additive manufacturing as compared with metals and polymers. Because ceramics cannot be cast or machined easily, three-dimensional (3D) printing enables a big leap in geometrical flexibility. We report preceramic monomers that are cured with ultraviolet light in a stereolithography 3D printer or through a patterned mask, forming 3D polymer structures that can have complex shape and cellular architecture. These polymer structures can be pyrolyzed to a ceramic with uniform shrinkage and virtually no porosity. Silicon oxycarbide microlattice and honeycomb cellular materials fabricated with this approach exhibit higher strength than ceramic foams of similar density. Additive manufacturing of such materials is of interest for propulsion components, thermal protection systems, porous burners, microelectromechanical systems, and electronic device packaging. PMID:26721993

  3. Additive manufacturing of polymer-derived ceramics

    NASA Astrophysics Data System (ADS)

    Eckel, Zak C.; Zhou, Chaoyin; Martin, John H.; Jacobsen, Alan J.; Carter, William B.; Schaedler, Tobias A.

    2016-01-01

    The extremely high melting point of many ceramics adds challenges to additive manufacturing as compared with metals and polymers. Because ceramics cannot be cast or machined easily, three-dimensional (3D) printing enables a big leap in geometrical flexibility. We report preceramic monomers that are cured with ultraviolet light in a stereolithography 3D printer or through a patterned mask, forming 3D polymer structures that can have complex shape and cellular architecture. These polymer structures can be pyrolyzed to a ceramic with uniform shrinkage and virtually no porosity. Silicon oxycarbide microlattice and honeycomb cellular materials fabricated with this approach exhibit higher strength than ceramic foams of similar density. Additive manufacturing of such materials is of interest for propulsion components, thermal protection systems, porous burners, microelectromechanical systems, and electronic device packaging.

  4. Polymer parametrized field theory

    SciTech Connect

    Laddha, Alok; Varadarajan, Madhavan

    2008-08-15

    Free scalar field theory on 2-dimensional flat spacetime, cast in diffeomorphism invariant guise by treating the inertial coordinates of the spacetime as dynamical variables, is quantized using loop quantum gravity (LQG) type 'polymer' representations for the matter field and the inertial variables. The quantum constraints are solved via group averaging techniques and, analogous to the case of spatial geometry in LQG, the smooth (flat) spacetime geometry is replaced by a discrete quantum structure. An overcomplete set of Dirac observables, consisting of (a) (exponentials of) the standard free scalar field creation-annihilation modes and (b) canonical transformations corresponding to conformal isometries, are represented as operators on the physical Hilbert space. None of these constructions suffer from any of the 'triangulation'-dependent choices which arise in treatments of LQG. In contrast to the standard Fock quantization, the non-Fock nature of the representation ensures that the group of conformal isometries as well as that of the gauge transformations generated by the constraints are represented in an anomaly free manner. Semiclassical states can be analyzed at the gauge invariant level. It is shown that 'physical weaves' necessarily underlie such states and that such states display semiclassicality with respect to, at most, a countable subset of the (uncountably large) set of observables of type (a). The model thus offers a fertile testing ground for proposed definitions of quantum dynamics as well as semiclassical states in LQG.

  5. The Importance of Carbon Fiber to Polymer Additive Manufacturing

    SciTech Connect

    Love, Lonnie J; Kunc, Vlastimil; Rios, Orlando; Duty, Chad E; Post, Brian K; Blue, Craig A

    2014-01-01

    Additive manufacturing holds tremendous promise in terms of revolutionizing manufacturing. However, fundamental hurdles limit mass adoption of the technology. First, production rates are extremely low. Second, the physical size of parts is generally small, less than a cubic foot. Third, while there is much excitement about metal additive manufacturing, the major growth area is in polymer additive manufacturing systems. Unfortunately, the mechanical properties of the polymer parts are poor, limiting the potential for direct part replacement. To address this issue, we describe three benefits of blending carbon fiber with polymer additive manufacturing. First, development of carbon fiber reinforced polymers for additive manufacturing achieves specific strengths approaching aerospace quality aluminum. Second, carbon fiber radically changes the behavior of the material during deposition, enabling large scale, out-of-the-oven, high deposition rate manufacturing. Finally, carbon fiber technology and additive manufacturing complement each other. Merging the two manufacturing processes enables the construction of complex components that would not be possible otherwise.

  6. Molecular Theories of Polymer Nanocomposites

    SciTech Connect

    Hall, Lisa M; Jayaraman, Arthi; Schweizer, Kenneth S

    2010-01-01

    Significant progress towards the development of microscopic predictive theories of the equilibrium structure, polymer-mediated interactions, and phase behavior of polymer nanocomposites has been made recently based on liquid state integral equation, density functional, and self-consistent mean field approaches. The basics of these three theoretical frameworks are summarized, and selected highlights of their recent applications discussed for spherical, nonspherical, and polymer-grafted nanoparticles dissolved in athermal and adsorbing concentrated solutions and homopolymer melts. The role of nanoparticle size, volume fraction, and interfacial cohesive interactions is emphasized, especially with regards to their influence on filler dispersion and spatial ordering via entropic depletion attraction, polymer adsorption-mediated steric stabilization, and local bridging of nanoparticles. Some of the many remaining theoretical challenges and open fundamental questions are summarized.

  7. Solid electrolyte material manufacturable by polymer processing methods

    DOEpatents

    Singh, Mohit; Gur, Ilan; Eitouni, Hany Basam; Balsara, Nitash Pervez

    2012-09-18

    The present invention relates generally to electrolyte materials. According to an embodiment, the present invention provides for a solid polymer electrolyte material that is ionically conductive, mechanically robust, and can be formed into desirable shapes using conventional polymer processing methods. An exemplary polymer electrolyte material has an elastic modulus in excess of 1.times.10.sup.6 Pa at 90 degrees C. and is characterized by an ionic conductivity of at least 1.times.10.sup.-5 Scm-1 at 90 degrees C. An exemplary material can be characterized by a two domain or three domain material system. An exemplary material can include material components made of diblock polymers or triblock polymers. Many uses are contemplated for the solid polymer electrolyte materials. For example, the present invention can be applied to improve Li-based batteries by means of enabling higher energy density, better thermal and environmental stability, lower rates of self-discharge, enhanced safety, lower manufacturing costs, and novel form factors.

  8. Evaluation of advanced polymers for additive manufacturing

    SciTech Connect

    Rios, Orlando; Morrison, Crystal

    2015-09-01

    The goal of this Manufacturing Demonstration Facility (MDF) technical collaboration project between Oak Ridge National Laboratory (ORNL) and PPG Industries, Inc. was to evaluate the feasibility of using conventional coatings chemistry and technology to build up material layer-by-layer. The PPG-ORNL study successfully demonstrated that polymeric coatings formulations may overcome many limitations of common thermoplastics used in additive manufacturing (AM), allow lightweight nozzle design for material deposition and increase build rate. The materials effort focused on layer-by-layer deposition of coatings with each layer fusing together. The combination of materials and deposition results in an additively manufactured build that has sufficient mechanical properties to bear the load of additional layers, yet is capable of bonding across the z-layers to improve build direction strength. The formulation properties were tuned to enable a novel, high-throughput deposition method that is highly scalable, compatible with high loading of reinforcing fillers, and is inherently low-cost.

  9. Additive Manufacturing of Ultem Polymers and Composites

    NASA Technical Reports Server (NTRS)

    Chuang, Kathy C.; Grady, Joseph E.; Draper, Robert D.; Shin, Euy-Sik E.; Patterson, Clark; Santelle, Thomas D.

    2015-01-01

    The objective of this project was to conduct additive manufacturing to produce aircraft engine components by Fused Deposition Modeling (FDM), using commercially available polyetherimdes Ultem 9085 and experimental Ultem 1000 filled with 10 chopped carbon fiber. A property comparison between FDM-printed and injection molded coupons for Ultem 9085, Ultem 1000 resin and the fiber-filled composite Ultem 1000 was carried out. Furthermore, an acoustic liner was printed from Ultem 9085 simulating conventional honeycomb structured liners and tested in a wind tunnel. Composite compressor inlet guide vanes were also printed using fiber-filled Ultem 1000 filaments and tested in a cascade rig. The fiber-filled Ultem 1000 filaments and composite vanes were characterized by scanning electron microscope (SEM) and acid digestion to determine the porosity of FDM-printed articles which ranged from 25-31. Coupons of Ultem 9085, experimental Ultem 1000 composites and XH6050 resin were tested at room temperature and 400F to evaluate their corresponding mechanical properties.

  10. Manufacturing Aspects of Advanced Polymer Composites for Automotive Applications

    NASA Astrophysics Data System (ADS)

    Friedrich, Klaus; Almajid, Abdulhakim A.

    2013-04-01

    Composite materials, in most cases fiber reinforced polymers, are nowadays used in many applications in which light weight and high specific modulus and strength are critical issues. The constituents of these materials and their special advantages relative to traditional materials are described in this paper. Further details are outlined regarding the present markets of polymer composites in Europe, and their special application in the automotive industry. In particular, the manufacturing of parts from thermoplastic as well as thermosetting, short and continuous fiber reinforced composites is emphasized.

  11. Towards roll-to-roll manufacturing of polymer photonic devices

    NASA Astrophysics Data System (ADS)

    Subbaraman, Harish; Lin, Xiaohui; Ling, Tao; Guo, L. Jay; Chen, Ray T.

    2014-03-01

    Traditionally, polymer photonic devices are fabricated using clean-room processes such as photolithography, e-beam lithography, reactive ion etching (RIE) and lift-off methods etc, which leads to long fabrication time, low throughput and high cost. We have utilized a novel process for fabricating polymer photonic devices using a combination of imprinting and ink jet printing methods, which provides high throughput on a variety of rigid and flexible substrates with low cost. We discuss the manufacturing challenges that need to be overcome in order to realize true implementation of roll-to-roll manufacturing of flexible polymer photonic systems. Several metrology and instrumentation challenges involved such as availability of particulate-free high quality substrate, development and implementation of high-speed in-line and off-line inspection and diagnostic tools with adaptive control for patterned and unpatterned material films, development of reliable hardware, etc need to be addressed and overcome in order to realize a successful manufacturing process. Due to extreme resolution requirements compared to print media, the burden of software and hardware tools on the throughput also needs to be carefully determined. Moreover, the effect of web wander and variations in web speed need to accurately be determined in the design of the system hardware and software. In this paper, we show the realization of solutions for few challenges, and utilizing these solutions for developing a high-rate R2R dual stage ink-jet printer that can provide alignment accuracy of <10μm at a web speed of 5m/min. The development of a roll-to-roll manufacturing system for polymer photonic systems opens limitless possibilities for the deployment of high performance components in a variety of applications including communication, sensing, medicine, agriculture, energy, lighting etc.

  12. Polymer multimode waveguide optical and electronic PCB manufacturing

    NASA Astrophysics Data System (ADS)

    Selviah, David R.

    2009-02-01

    The paper describes the research in the Â#1.3 million IeMRC Integrated Optical and Electronic Interconnect PCB Manufacturing (OPCB) Flagship Project in which 8 companies and 3 universities carry out collaborative research and which was formed and is technically led by the author. The consortium's research is aimed at investigating a range of fabrication techniques, some established and some novel, for fabricating polymer multimode waveguides from several polymers, some formulations of which are being developed within the project. The challenge is to develop low cost waveguide manufacturing techniques compatible with commercial PCB manufacturing and to reduce their alignment cost. The project aims to take the first steps in making this hybrid optical waveguide and electrical copper track printed circuit board disruptive technology widely available by establishing and incorporating waveguide design rules into commercial PCB layout software and transferring the technology for fabricating such boards to a commercial PCB manufacturer. To focus the research the project is designing an optical waveguide backplane to tight realistic constraints, using commercial layout software with the new optical design rules, for a demonstrator into which 4 daughter cards are plugged, each carrying an aggregate of 80 Gb/s data so that each waveguide carries 10 Gb/s.

  13. On causality in polymer scalar field theory

    NASA Astrophysics Data System (ADS)

    García-Chung, Angel A.; Morales-Técotl, Hugo A.

    2011-10-01

    The properties of spacetime corresponding to a proposed quantum gravity theory might modify the high energy behavior of quantum fields. Motivated by loop quantum gravity, recently, Hossain et al [1] have considered a polymer field algebra that replaces the standard canonical one in order to calculate the propagator of a real scalar field in flat spacetime. This propagator features Lorentz violations. Motivated by the relation between Lorentz invariance and causality in standard Quantum Field Theory, in this work we investigate the causality behavior of the polymer scalar field.

  14. Electrooptic polymer voltage sensor and method of manufacture thereof

    NASA Technical Reports Server (NTRS)

    Gottsche, Allan (Inventor); Perry, Joseph W. (Inventor)

    1993-01-01

    An optical voltage sensor utilizing an electrooptic polymer is disclosed for application to electric power distribution systems. The sensor, which can be manufactured at low cost in accordance with a disclosed method, measures voltages across a greater range than prior art sensors. The electrooptic polymer, which replaces the optical crystal used in prior art sensors, is sandwiched directly between two high voltage electrodes. Voltage is measured by fiber optical means, and no voltage division is required. The sample of electrooptic polymer is fabricated in a special mold and later mounted in a sensor housing. Alternatively, mold and sensor housing may be identical. The sensor housing is made out of a machinable polymeric material and is equipped with two opposing optical windows. The optical windows are mounted in the bottom of machined holes in the wall of the mold. These holes provide for mounting of the polarizing optical components and for mounting of the fiber optic connectors. One connecting fiber is equipped with a light emitting diode as a light source. Another connecting fiber is equipped with a photodiode as a detector.

  15. Theory and Simulations of Tapered Diblock Polymers

    NASA Astrophysics Data System (ADS)

    Hall, Lisa M.; Seo, Youngmi; Brown, Jonathan R.

    We study tapered block polymers, AB diblock polymers with a gradient region inserted between the pure A and B blocks such that composition smoothly transitions from A to B (or B to A in the case of inverse tapers). Phase diagrams were created using self consistent field theory (SCFT), and coarse-grained molecular dynamics (MD) simulations were used to study polymer conformations and diffusion, including diffusion of monomer-sized penetrants preferentially dissolved in one of the phases. As has been observed experimentally, we find that tapering makes the A and B blocks more miscible, decreasing domain spacing and shifting the order to disorder transition to lower temperatures. We predict a widening of the bicontinuous double gyroid region of the phase diagram for moderate length normal tapers versus diblocks, suggesting taper length can be used as a control parameter to obtain network phases even at high molecular weight, as may be desirable in transport applications. Additionally, in some inverse tapered systems, SCFT predicts phases not present in the standard AB diblock phase diagram, and MD simulations show how the chains fold back and forth across the interface. In these inverse tapered polymers, as segregation strength is increased, the competing effects of folding and stretching produces lamellae that have domain spacing nearly independent of temperature. We also find that diffusion of penetrants in normal tapers is significantly faster than that in inverse tapers, which is likely related to their unusual conformations. This material is based upon work supported by DOE Grant SC0014209.

  16. Low-Cost Manufacturing of High- Temperature Polymer Composites

    NASA Technical Reports Server (NTRS)

    Sutter, James K.

    1998-01-01

    Major goals of NASA and the Integrated High Performance Turbine Engine Technology (IHPTET) initiative include improvements in the affordability of propulsion systems, significant increases in the thrust/weight ratio, and increases in the temperature capability of components of gas turbine engines. Members of NASA Lewis Research Center's HITEMP project worked cooperatively with Allison Advanced Development Corporation to develop a manufacturing method to produce low-cost components for gas turbine engines. Affordability for these polymer composites is defined by the savings in acquisition and life-cycle costs associated with engine weight reduction. To lower engine component costs, the Lewis/Allison team focused on chopped graphite fiber/polyimide resin composites. The high-temperature polyimide resin chosen, PMR-II-50, was developed at NASA Lewis.

  17. Bottlebrush Block Polymers: Quantitative Theory and Experiments.

    PubMed

    Dalsin, Samuel J; Rions-Maehren, Thomas G; Beam, Marissa D; Bates, Frank S; Hillmyer, Marc A; Matsen, Mark W

    2015-12-22

    The self-assembly of bottlebrush block polymers into a lamellar phase was investigated using a combination of experiment and self-consistent field theory (SCFT). Nine diblock bottlebrush polymers were synthesized with atactic polypropylene side chains (block A) and polystyrene side chains (block B) attached to poly(norbornene) backbones of various contour lengths, L, and the resulting lamellar structures were analyzed using small-angle X-ray scattering. The scaling of the lamellar period, d0 ∼ L(γ), exhibited an increasing exponent from γ ≈ 0.3 at small L to γ ≈ 0.9 at large L. The small exponents occurred for starlike molecules where the size of the side chains is comparable to L, while the larger exponents occurred for the more brushlike molecules where the side chains extend radially outward from the backbone. The bottlebrushes were then modeled using flexible side chains of types A and B attached to a semiflexible backbone with an adjustable persistence length, ξb. The resulting SCFT predictions for d0 showed remarkable quantitative agreement with the experimental data, where ξb was similar to the radius of the bottlebrushes. The theory was then used to examine the joint-distribution functions for the position and orientation of different segments along the backbone. This revealed a bilayer arrangement of the bottlebrushes in the lamellar phase, with a high degree of backbone orientation at the A/B interfaces that almost completely vanished near the center of the domains. This finding clearly refutes the prevailing interpretation that the large scaling exponent γ is a result of highly extended backbone conformations. PMID:26544636

  18. Sustainable design and manufacturing of multifunctional polymer nanocomposite coatings: A multiscale systems approach

    NASA Astrophysics Data System (ADS)

    Xiao, Jie

    Polymer nanocomposites have a great potential to be a dominant coating material in a wide range of applications in the automotive, aerospace, ship-making, construction, and pharmaceutical industries. However, how to realize design sustainability of this type of nanostructured materials and how to ensure the true optimality of the product quality and process performance in coating manufacturing remain as a mountaintop area. The major challenges arise from the intrinsic multiscale nature of the material-process-product system and the need to manipulate the high levels of complexity and uncertainty in design and manufacturing processes. This research centers on the development of a comprehensive multiscale computational methodology and a computer-aided tool set that can facilitate multifunctional nanocoating design and application from novel function envisioning and idea refinement, to knowledge discovery and design solution derivation, and further to performance testing in industrial applications and life cycle analysis. The principal idea is to achieve exceptional system performance through concurrent characterization and optimization of materials, product and associated manufacturing processes covering a wide range of length and time scales. Multiscale modeling and simulation techniques ranging from microscopic molecular modeling to classical continuum modeling are seamlessly coupled. The tight integration of different methods and theories at individual scales allows the prediction of macroscopic coating performance from the fundamental molecular behavior. Goal-oriented design is also pursued by integrating additional methods for bio-inspired dynamic optimization and computational task management that can be implemented in a hierarchical computing architecture. Furthermore, multiscale systems methodologies are developed to achieve the best possible material application towards sustainable manufacturing. Automotive coating manufacturing, that involves paint spay and

  19. de Gennes's theory of polymer drag reduction revisited

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Hyun; Akhavan, Rayhaneh

    2010-11-01

    The original theory of polymer drag reduction proposed by de Gennes [1] and its re-interpretation for wall-bounded flows proposed by Sreenivasan & White [2] give predictions which are orders of magnitude off from both DNS results and available experimental data. A revised version of this theory is developed, in which the effect of the mean shear on polymer stretching is included, and the polymer is assumed to affect the dynamics of a turbulent scale when a small fraction, on the order of ˜3%, of the turbulence kinetic energy at that scale is redirected into the elastic energy of polymer. The revised theory gives predictions in quantitative agreement with DNS and experimental results for a number of polymer drag reduction features, including the criteria for onset of drag reduction, saturation of drag reduction, MDR, and the range of turbulent scales affected by the polymer. A complete theory of polymer drag reduction is proposed to show how this minimal exchange of energy between the polymer and turbulence can lead to the dramatic drag reductions observed with polymers.[4pt] [1] de Gennes, Physica 140A, p.9 (1986).[0pt] [2] Sreenivasan & White, J. Fluid Mech. 409, p.149 (2000)

  20. Model-predictive control of polymer composite manufacturing processes

    NASA Astrophysics Data System (ADS)

    Voorakaranam, Srikanth

    Quality control is crucial for reducing costs and enabling a more widespread use of fiber-resin composites. This research focuses on development of model-based control strategies for controlling product quality in continuous processes for manufacturing polymer composites with injected pultrusion as a prototype. The control objective is to maximize production rates, meeting quality criteria such as eliminating voids, achieving desired degree of cure and preventing backflow of resin from the die entrance. A 2-D mathematical model of IP developed by Kommu is extended to incorporate die dynamics. Exercising the model over a range of operating conditions, the requirements for a control system are formulated. Simultaneous requirements of optimization and control are met by using a cascade strategy consisting of supervisory and regulatory layers. The supervisory layer consists of an optimizer in conjunction with a steady-state cure model and an injection pressure model. The cure model is linear in important process variables. The injection pressure model is also linear in pullspeed. A linear program generates setpoints for pullspeed, injection pressure and temperatures in the three zones of the die which are implemented by the regulatory layer using multiple PID controllers. This formulation operates the process optimally. A major problem in feedback control of the IP process is the inability to measure quality variables on-line. An inferential control strategy is proposed to tackle this. It is then extended so that it can be implemented in a model predictive control formulation. This novel strategy called model predictive inferential control is general enough to accommodate multiple secondary measurements as well as nonlinear estimators and controllers. Collinearity among multiple measurements is addressed through principal component regression. The estimator uses frequent secondary measurements to estimate the effect of the disturbances on the primary variable which are

  1. Hamiltonian constraint in polymer parametrized field theory

    SciTech Connect

    Laddha, Alok; Varadarajan, Madhavan

    2011-01-15

    Recently, a generally covariant reformulation of two-dimensional flat spacetime free scalar field theory known as parametrized field theory was quantized using loop quantum gravity (LQG) type ''polymer'' representations. Physical states were constructed, without intermediate regularization structures, by averaging over the group of gauge transformations generated by the constraints, the constraint algebra being a Lie algebra. We consider classically equivalent combinations of these constraints corresponding to a diffeomorphism and a Hamiltonian constraint, which, as in gravity, define a Dirac algebra. Our treatment of the quantum constraints parallels that of LQG and obtains the following results, expected to be of use in the construction of the quantum dynamics of LQG: (i) the (triangulated) Hamiltonian constraint acts only on vertices, its construction involves some of the same ambiguities as in LQG and its action on diffeomorphism invariant states admits a continuum limit, (ii) if the regulating holonomies are in representations tailored to the edge labels of the state, all previously obtained physical states lie in the kernel of the Hamiltonian constraint, (iii) the commutator of two (density weight 1) Hamiltonian constraints as well as the operator correspondent of their classical Poisson bracket converge to zero in the continuum limit defined by diffeomorphism invariant states, and vanish on the Lewandowski-Marolf habitat, (iv) the rescaled density 2 Hamiltonian constraints and their commutator are ill-defined on the Lewandowski-Marolf habitat despite the well-definedness of the operator correspondent of their classical Poisson bracket there, (v) there is a new habitat which supports a nontrivial representation of the Poisson-Lie algebra of density 2 constraints.

  2. Solid Rocket Fuel Constitutive Theory and Polymer Cure

    NASA Technical Reports Server (NTRS)

    Ream, Robert

    2006-01-01

    Solid Rocket Fuel is a complex composite material for which no general constitutive theory, based on first principles, has been developed. One of the principles such a relation would depend on is the morphology of the binder. A theory of polymer curing is required to determine this morphology. During work on such a theory an algorithm was developed for counting the number of ways a polymer chain could assemble. The methods used to develop and check this algorithm led to an analytic solution to the problem. This solution is used in a probability distribution function which characterizes the morphology of the polymer.

  3. New Molecular Theory for Dense, Thin Polymer Films

    NASA Astrophysics Data System (ADS)

    Freed, Karl

    2015-03-01

    The development of a molecular theory for dense polymer systems ranks among the most challenging problems in the statistical mechanics of complex matter. These difficulties become compounded when considering the influence of molecular details on thermodynamic properties of thin polymer films, properties deviating from those of the bulk phases. A new theory of dense polymer films is developed as a significant generalization of methods used to devise the lattice cluster theory, an extension of Flory-Huggins theory that include details of monomer structure and short range correlations (neglected in FH theory) and that has successfully been applied to a wide range of polymer systems. The new theory incorporates the essential ``transport'' constraints of Helfand and focuses on the strict imposition of excluded volume constraints, appropriate to dense polymer systems, rather than the maintenance of chain connectivity as appropriate for lower densities and implemented in self-consistent theories of polymer adsorption at interfaces. The theory is illustrated by presenting examples of the computed density and chain end profiles for free standing films as a function of bulk density, chain length, temperature, and chain semi-flexibility.

  4. Hydrodynamic theories for mixtures of polymers and rodlike liquid crystalline polymers.

    PubMed

    Forest, M Gregory; Wang, Qi

    2005-10-01

    We develop a hydrodynamic theory for flows of incompressible blends of flexible polymers and rodlike nematic polymers (RNPs) or rodlike nematic liquid crystal polymers (RNLCPs) extending the thermodynamical theory of Muratov and E [J. Chem. Phys. 116, 4723 (2002)] for phase separation kinetics of the blend. We model the flexible polymer molecules in the polymer matrix as Rouse chains and assume the translational diffusion of the molecules is predominantly through the volume fraction of the flexible polymer and the molecules of rodlike nematic liquid crystal polymers. We then (i) derive the translational flux for the rodlike nematic liquid crystal polymers to ensure the incompressibility constraint; (ii) derive the elastic stress tensor, accounting for the contribution from both the rodlike nematic polymer and the flexible polymer matrix, as well as the extra elastic body force due to the nonlocal intermolecular potential for long range molecular interaction; (iii) show that the theory obeys positive entropy production and thereby satisfies the second law of thermodynamics. By applying the gradient expansion technique on the number density function of RNLCPs, we present an approximate, weakly nonlocal theory in differential form in which the intermolecular potential is given by gradients of the number density function of the RNLCP and the volume fraction of the flexible polymer. In the approximate theory, the elastic stress is augmented by an extra stress tensor due to the spatial convection of the macroscopic material point and long range interaction, whose divergence yields the analogous extra elastic body force with respect to the nonlocal intermolecular potential. Finally, we compare the model in steady simple shear with the Doi theory for bulk monodomains of rodlike nematic polymers. PMID:16383413

  5. Innovative hybrid optics: combining the thermal stability of glass with low manufacturing cost of polymers

    NASA Astrophysics Data System (ADS)

    Doushkina, Valentina

    2010-08-01

    Innovative hybrid glass-polymer optical solutions on a component, module, or system level offer thermal stability of glass with low manufacturing cost of polymers reducing component weight, enhancing the safety and appeal of the products. Narrow choice of polymer materials is compensated by utilizing sophisticated optical surfaces such as refractive, reflective, and diffractive substrates with spherical, aspherical, cylindrical, and freeform prescriptions. Current advancements in polymer technology and injection molding capabilities placed polymer optics in the heart of many high tech devices and applications including Automotive Industry, Defense & Aerospace; Medical/Bio Science; Projection Displays, Sensors, Information Technology, Commercial and Industrial. This paper is about integration of polymer and glass optics for enhanced optical performance with reduced number of components, thermal stability, and low manufacturing cost. The listed advantages are not achievable when polymers or glass optics are used as stand-alone. The author demonstrates that integration of polymer and glass on component or optical system level on one hand offers high resolution and diffraction limited image quality, similar to the glass optics with stable refractive index and stable thermal performance when design is athermalized within the temperature range. On the other hand, the integrated hybrid solution significantly reduces cost, weight, and complexity, just like the polymer optics. The author will describe the design and analyzes process of combining glass and polymer optics for variety of challenging applications such as fast optics with low F/#, wide field of view lenses or systems, free form optics, etc.

  6. Polymer networks and gels: Simulation and theory

    NASA Astrophysics Data System (ADS)

    Kenkare, Nirupama Ramamurthy

    1998-12-01

    The purpose of this research is to understand the molecular origins of the dynamic and swelling properties of polymer networks and gels. Our approach has been to apply computer simulations techniques to off-lattice, near-perfect, trifunctional and tetrafunctional network models. The networks are constructed by endlinking freely-jointed, tangent-hard-sphere chains. Equilibrium discontinuous molecular dynamics techniques are employed to simulate the relaxation of large networks of chain lengths ranging from N = 20 to N = 150 at a packing fraction of 0.43. The simulation trajectories are used to calculate the radius of gyration and end-to-end distance of the network chains, the static structure factor of the crosslinks, the mean-squared displacement of the crosslinks and chain inner segments, the intermediate scattering function of the chains and the elastic modulus of the network. The structure and properties of the networks are shown to depend heavily on the manner in which the network is initially constructed. The dynamics of the network crosslinks and chain inner segments are similar to those of melt chains at short times and show evidence of spatial localization at long times. The results from the elastic moduli and long-time crosslink and chain displacement calculations indicate that entanglement constraints act in conjunction with crosslink constraints to reduce crosslink and chain mobility. The presence of entanglements appears to cause the magnitude of the elastic modulus to be larger than the affine/phantom model predictions. The pressure-volume behavior and the chain configurational properties of deformed networks are investigated over a range of packing fractions. The variation of network pressure with density is found to be similar to that of uncrosslinked chain systems of the same chain length, except at low densities where the network pressures become negative due to elastic effects. We derive a simple, mean-field network equation of state in which the

  7. Manufacturing polymer thin films in a micro-gravity environment

    NASA Technical Reports Server (NTRS)

    Vera, Ivan

    1987-01-01

    This project represents Venezuela's first scientific experiment in space. The apparatus for the automatic casting of two polymer thin films will be contained in NASA's Payload No. G-559 of the Get Away Special program for a future orbital space flight in the U.S. Space Shuttle. Semi-permeable polymer membranes have important applications in a variety of fields, such as medicine, energy, and pharmaceuticals and in general fluid separation processes, such as reverse osmosis, ultrafiltration, and electrodialysis. The casting of semi-permeable membranes in space will help to identify the roles of convection in determining the structure of these membranes.

  8. Tridimensional ionic polymer metal composites: optimization of the manufacturing techniques

    NASA Astrophysics Data System (ADS)

    Bonomo, C.; Bottino, M.; Brunetto, P.; Di Pasquale, G.; Fortuna, L.; Graziani, S.; Pollicino, A.

    2010-05-01

    Ionic polymer metal composites (IPMCs) belong to electroactive polymers (EAPs) and have been suggested for various applications due to their light weight and to the fact that they react mechanically when stimulated by an electrical signal and vice versa. Thick IPMCs (3D-IPMCs) have been fabricated by hot pressing several Nafion® 117 films. Additional post-processes (more cycles of Pt electroless plating and dispersing agents) have been applied to improve the 3D-IPMC performance. The electromechanical response of 3D-IPMCs has been examined by applying electrical signals and measuring the displacement and blocking force produced.

  9. Investigating accidents involving aircraft manufactured from polymer composite materials

    NASA Astrophysics Data System (ADS)

    Dunn, Leigh

    This study looks into the examination of polymer composite wreckage from the perspective of the aircraft accident investigator. It develops an understanding of the process of wreckage examination as well as identifying the potential for visual and macroscopic interpretation of polymer composite aircraft wreckage. The in-field examination of aircraft wreckage, and subsequent interpretations of material failures, can be a significant part of an aircraft accident investigation. As the use of composite materials in aircraft construction increases, the understanding of how macroscopic failure characteristics of composite materials may aid the field investigator is becoming of increasing importance.. The first phase of this research project was to explore how investigation practitioners conduct wreckage examinations. Four accident investigation case studies were examined. The analysis of the case studies provided a framework of the wreckage examination process. Subsequently, a literature survey was conducted to establish the current level of knowledge on the visual and macroscopic interpretation of polymer composite failures. Relevant literature was identified and a compendium of visual and macroscopic characteristics was created. Two full-scale polymer composite wing structures were loaded statically, in an upward bending direction, until each wing structure fractured and separated. The wing structures were subsequently examined for the existence of failure characteristics. The examination revealed that whilst characteristics were present, the fragmentation of the structure destroyed valuable evidence. A hypothetical accident scenario utilising the fractured wing structures was developed, which UK government accident investigators subsequently investigated. This provided refinement to the investigative framework and suggested further guidance on the interpretation of polymer composite failures by accident investigators..

  10. Highly oriented carbon fiber–polymer composites via additive manufacturing

    DOE PAGESBeta

    Tekinalp, Halil L.; Kunc, Vlastimil; Velez-Garcia, Gregorio M.; Duty, Chad E.; Love, Lonnie J.; Naskar, Amit K.; Blue, Craig A.; Ozcan, Soydan

    2014-10-16

    Additive manufacturing, diverging from traditional manufacturing techniques, such as casting and machining materials, can handle complex shapes with great design flexibility without the typical waste. Although this technique has been mainly used for rapid prototyping, interest is growing in using this method to directly manufacture actual parts of complex shape. To use 3D-printing additive manufacturing in wide spread applications, the technique and the feedstock materials require improvements to meet the mechanical requirements of load-bearing components. Thus, we investigated the short fiber (0.2 mm to 0.4 mm) reinforced acrylonitrile-butadiene-styrene composites as a feedstock for 3D-printing in terms of their processibility, microstructuremore » and mechanical performance; and also provided comparison with traditional compression molded composites. The tensile strength and modulus of 3D-printed samples increased ~115% and ~700%, respectively. 3D-printer yielded samples with very high fiber orientation in printing direction (up to 91.5 %), whereas, compression molding process yielded samples with significantly less fiber orientation. Microstructure-mechanical property relationships revealed that although the relatively high porosity is observed in the 3D-printed composites as compared to those produced by the conventional compression molding technique, they both exhibited comparable tensile strength and modulus. Furthermore, this phenomena is explained based on the changes in fiber orientation, dispersion and void formation.« less

  11. Highly oriented carbon fiber–polymer composites via additive manufacturing

    SciTech Connect

    Tekinalp, Halil L.; Kunc, Vlastimil; Velez-Garcia, Gregorio M.; Duty, Chad E.; Love, Lonnie J.; Naskar, Amit K.; Blue, Craig A.; Ozcan, Soydan

    2014-10-16

    Additive manufacturing, diverging from traditional manufacturing techniques, such as casting and machining materials, can handle complex shapes with great design flexibility without the typical waste. Although this technique has been mainly used for rapid prototyping, interest is growing in using this method to directly manufacture actual parts of complex shape. To use 3D-printing additive manufacturing in wide spread applications, the technique and the feedstock materials require improvements to meet the mechanical requirements of load-bearing components. Thus, we investigated the short fiber (0.2 mm to 0.4 mm) reinforced acrylonitrile-butadiene-styrene composites as a feedstock for 3D-printing in terms of their processibility, microstructure and mechanical performance; and also provided comparison with traditional compression molded composites. The tensile strength and modulus of 3D-printed samples increased ~115% and ~700%, respectively. 3D-printer yielded samples with very high fiber orientation in printing direction (up to 91.5 %), whereas, compression molding process yielded samples with significantly less fiber orientation. Microstructure-mechanical property relationships revealed that although the relatively high porosity is observed in the 3D-printed composites as compared to those produced by the conventional compression molding technique, they both exhibited comparable tensile strength and modulus. Furthermore, this phenomena is explained based on the changes in fiber orientation, dispersion and void formation.

  12. Polymeric compositions and their method of manufacture. [forming filled polymer systems using cryogenics

    NASA Technical Reports Server (NTRS)

    Moser, B. G.; Landel, R. F. (Inventor)

    1972-01-01

    Filled polymer compositions are made by dissolving the polymer binder in a suitable sublimable solvent, mixing the filler material with the polymer and its solvent, freezing the resultant mixture, and subliming the frozen solvent from the mixture from which it is then removed. The remaining composition is suitable for conventional processing such as compression molding or extruding. A particular feature of the method of manufacture is pouring the mixed solution slowly in a continuous stream into a cryogenic bath wherein frozen particles of the mixture result. The frozen individual particles are then subjected to the sublimation.

  13. Fluid Structure Interaction Analysis in Manufacturing Metal/Polymer Macro-Composites

    SciTech Connect

    Baesso, R.; Lucchetta, G.

    2007-05-17

    Polymer Injection Forming (PIF) is a new manufacturing technology for sheet metal-polymer macro-composites, which results from the combination of injection moulding and sheet metal forming. This process consists on forming the sheet metal according to the boundary of the mould cavity by means of the injected polymer. After cooling, the polymer bonds permanently to the metal resulting in a sheet metal-polymer macro-composite product. Comparing this process to traditional ones (where the polymeric and metal parts are joined together after separate forming) the main advantages are both reduction of production costs and increase of part quality. This paper presents a multi-physics numerical simulation of the process performed in the Ansys/CFX environment.

  14. Lattice cluster theory for dense, thin polymer films

    NASA Astrophysics Data System (ADS)

    Freed, Karl F.

    2015-04-01

    While the application of the lattice cluster theory (LCT) to study the miscibility of polymer blends has greatly expanded our understanding of the monomer scale molecular details influencing miscibility, the corresponding theory for inhomogeneous systems has not yet emerged because of considerable technical difficulties and much greater complexity. Here, we present a general formulation enabling the extension of the LCT to describe the thermodynamic properties of dense, thin polymer films using a high dimension, high temperature expansion. Whereas the leading order of the LCT for bulk polymer systems is essentially simple Flory-Huggins theory, the highly non-trivial leading order inhomogeneous LCT (ILCT) for a film with L layers already involves the numerical solution of 3(L - 1) coupled, highly nonlinear equations for the various density profiles in the film. The new theory incorporates the essential "transport" constraints of Helfand and focuses on the strict imposition of excluded volume constraints, appropriate to dense polymer systems, rather than the maintenance of chain connectivity as appropriate for lower densities and as implemented in self-consistent theories of polymer adsorption at interfaces. The ILCT is illustrated by presenting examples of the computed profiles of the density, the parallel and perpendicular bonds, and the chain ends for free standing and supported films as a function of average film density, chain length, temperature, interaction with support, and chain stiffness. The results generally agree with expected general trends.

  15. Lattice cluster theory for dense, thin polymer films

    SciTech Connect

    Freed, Karl F.

    2015-04-07

    While the application of the lattice cluster theory (LCT) to study the miscibility of polymer blends has greatly expanded our understanding of the monomer scale molecular details influencing miscibility, the corresponding theory for inhomogeneous systems has not yet emerged because of considerable technical difficulties and much greater complexity. Here, we present a general formulation enabling the extension of the LCT to describe the thermodynamic properties of dense, thin polymer films using a high dimension, high temperature expansion. Whereas the leading order of the LCT for bulk polymer systems is essentially simple Flory-Huggins theory, the highly non-trivial leading order inhomogeneous LCT (ILCT) for a film with L layers already involves the numerical solution of 3(L − 1) coupled, highly nonlinear equations for the various density profiles in the film. The new theory incorporates the essential “transport” constraints of Helfand and focuses on the strict imposition of excluded volume constraints, appropriate to dense polymer systems, rather than the maintenance of chain connectivity as appropriate for lower densities and as implemented in self-consistent theories of polymer adsorption at interfaces. The ILCT is illustrated by presenting examples of the computed profiles of the density, the parallel and perpendicular bonds, and the chain ends for free standing and supported films as a function of average film density, chain length, temperature, interaction with support, and chain stiffness. The results generally agree with expected general trends.

  16. Model based control of polymer composite manufacturing processes

    NASA Astrophysics Data System (ADS)

    Potaraju, Sairam

    2000-10-01

    The objective of this research is to develop tools that help process engineers design, analyze and control polymeric composite manufacturing processes to achieve higher productivity and cost reduction. Current techniques for process design and control of composite manufacturing suffer from the paucity of good process models that can accurately represent these non-linear systems. Existing models developed by researchers in the past are designed to be process and operation specific, hence generating new simulation models is time consuming and requires significant effort. To address this issue, an Object Oriented Design (OOD) approach is used to develop a component-based model building framework. Process models for two commonly used industrial processes (Injected Pultrusion and Autoclave Curing) are developed using this framework to demonstrate the flexibility. Steady state and dynamic validation of this simulator is performed using a bench scale injected pultrusion process. This simulator could not be implemented online for control due to computational constraints. Models that are fast enough for online implementation, with nearly the same degree of accuracy are developed using a two-tier scheme. First, lower dimensional models that captures essential resin flow, heat transfer and cure kinetics important from a process monitoring and control standpoint are formulated. The second step is to reduce these low dimensional models to Reduced Order Models (ROM) suited for online model based estimation, control and optimization. Model reduction is carried out using Proper Orthogonal Decomposition (POD) technique in conjunction with a Galerkin formulation procedure. Subsequently, a nonlinear model-based estimation and inferential control scheme based on the ROM is implemented. In particular, this research work contributes in the following general areas: (1) Design and implementation of versatile frameworks for modeling and simulation of manufacturing processes using object

  17. Theory of colloid depletion stabilization by unattached and adsorbed polymers.

    PubMed

    Semenov, A N; Shvets, A A

    2015-12-01

    The polymer-induced forces between colloidal particles in a semidilute or concentrated polymer solution are considered theoretically. This study is focussed on the case of partially adsorbing colloidal surfaces involving some attractive centers able to trap polymer segments. In the presence of free polymers the particles are covered by self-assembled fluffy layers whose structure is elucidated. It is shown that the free-polymer-induced interaction between the particles is repulsive at distances exceeding the polymer correlation length, and that this depletion repulsion can be strongly enhanced due to the presence of fluffy layers. This enhanced depletion stabilization mechanism (which works in tandem with a more short-range steric repulsion of fluffy layers) can serve on its own to stabilize colloidal dispersions. More generally, we identify three main polymer-induced interaction mechanisms: depletion repulsion, depletion attraction, and steric repulsion. Their competition is analyzed both numerically and analytically based on an asymptotically rigorous mean-field theory. It is shown that colloid stabilization can be achieved by simply increasing the molecular weight of polymer additives, or by changing their concentration. PMID:26400677

  18. Manufacturing of embedded multimode waveguides by reactive lamination of cyclic olefin polymer and polymethylmethacrylate

    NASA Astrophysics Data System (ADS)

    Kelb, Christian; Rother, Raimund; Schuler, Anne-Katrin; Hinkelmann, Moritz; Rahlves, Maik; Prucker, Oswald; Müller, Claas; Rühe, Jürgen; Reithmeier, Eduard; Roth, Bernhard

    2016-03-01

    We demonstrate the manufacturing of embedded multimode optical waveguides through linking of polymethylmethacrylate (PMMA) foils and cyclic olefin polymer (COP) filaments based on a lamination process. Since the two polymeric materials cannot be fused together through interdiffusion of polymer chains, we utilize a reactive lamination agent based on PMMA copolymers containing photoreactive 2-acryloyloxyanthraquinone units, which allows the creation of monolithic PMMA-COP substrates through C-H insertion reactions across the interface between the two materials. We elucidate the lamination process and evaluate the chemical link between filament and foils by carrying out extraction tests with a custom-built tensile testing machine. We also show attenuation measurements of the manufactured waveguides for different manufacturing parameters. The lamination process is in particular suited for large-scale and low-cost fabrication of board-level devices with optical waveguides or other micro-optical structures, e.g., optofluidic devices.

  19. Terahertz imaging and tomography as efficient instruments for testing polymer additive manufacturing objects.

    PubMed

    Perraud, J B; Obaton, A F; Bou-Sleiman, J; Recur, B; Balacey, H; Darracq, F; Guillet, J P; Mounaix, P

    2016-05-01

    Additive manufacturing (AM) technology is not only used to make 3D objects but also for rapid prototyping. In industry and laboratories, quality controls for these objects are necessary though difficult to implement compared to classical methods of fabrication because the layer-by-layer printing allows for very complex object manufacturing that is unachievable with standard tools. Furthermore, AM can induce unknown or unexpected defects. Consequently, we demonstrate terahertz (THz) imaging as an innovative method for 2D inspection of polymer materials. Moreover, THz tomography may be considered as an alternative to x-ray tomography and cheaper 3D imaging for routine control. This paper proposes an experimental study of 3D polymer objects obtained by additive manufacturing techniques. This approach allows us to characterize defects and to control dimensions by volumetric measurements on 3D data reconstructed by tomography. PMID:27140357

  20. Theory of polymer-dispersed cholesteric liquid crystals

    SciTech Connect

    Matsuyama, Akihiko

    2013-11-07

    A mean field theory is presented to describe cholesteric phases in mixtures of a polymer and a cholesteric liquid crystal. Taking into account an anisotropic coupling between a polymer and a liquid crystal, we examine the helical pitch, twist elastic constant, and phase separations. Analytical expressions of the helical pitch of a cholesteric phase and the twist elastic constant are derived as a function of the orientational order parameters of a polymer and a liquid crystal and two intermolecular interaction parameters. We also find isotropic-cholesteric, cholesteric-cholesteric phase separations, and polymer-induced cholesteric phase on the temperature-concentration plane. We demonstrate that an anisotropic coupling between a polymer and a liquid crystal can stabilize a cholesteric phase in the mixtures. Our theory can also apply to mixtures of a nematic liquid crystal and a chiral dopant. We discuss the helical twisting power, which depends on temperature, concentration, and orientational order parameters. It is shown that our theory can qualitatively explain experimental observations.

  1. Innovative Manufacturing of Carbon Nanotube-Loaded Fibrillar Polymer Composites

    NASA Astrophysics Data System (ADS)

    Lin, R. J. T.; Bhattacharyya, D.; Fakirov, S.

    The concept of microfibrillar composite (MFC) has been used to create a new type of polymer composites, in which the reinforcing microfibrils are loaded with carbon nanotubes (CNT). Polyamide 66 (PA66) has been melt blended with polypropylene in a twin screw extruder with and without CNT, and thereafter cold drawn to create a fibrillar state as well as to align the CNT in the PA66 microfibrils. The drawn bristles were compression moulded at 180°C to prepare MFC plates. The scanning electron microscope (SEM) observations indicate near perfect distribution of CNT in the reinforcing PA66 microfibrils. Although the fibrillated PA66 is able to improve the tensile stiffness and strength as expected from the MFC structure, the incorporation of CNT does not exhibit any further enhancing effect. It rather adversely affects the mechanical properties due to poor interface adhesion between the matrix and the reinforcing microfibrils with the presence of CNT, as demonstrated by SEM. However, the resulting highly aligned CNT within the MFC are expected to affect the physical and functional properties of these composites.

  2. Flow induced migration in polymer melts - Theory and simulation

    NASA Astrophysics Data System (ADS)

    Dorgan, John Robert; Rorrer, Nicholas Andrew

    2015-04-01

    Flow induced migration, whereby polymer melts are fractionated by molecular weight across a flow field, represents a significant complication in the processing of polymer melts. Despite its long history, such phenomena remain relatively poorly understood. Here a simple analytical theory is presented which predicts the phenomena based on well-established principles of non-equilibrium thermodynamics. It is unambiguously shown that for purely viscous materials, a gradient in shear rate is needed to drive migration; for purely viscometric flows no migration is expected. Molecular scale simulations of flow migration effects in dense polymer melts are also presented. In shear flow the melts exhibit similar behavior as the quiescent case; a constant shear rate across the gap does not induce chain length based migration. In comparison, parabolic flow causes profound migration for both unentangled and entangled melts. These findings are consistent with the analytical theory. The picture that emerges is consistent with flow induced migration mechanisms predominating over competing chain degradation mechanisms.

  3. Renormalized field theory of collapsing directed randomly branched polymers.

    PubMed

    Janssen, Hans-Karl; Wevelsiep, Frank; Stenull, Olaf

    2009-10-01

    We present a dynamical field theory for directed randomly branched polymers and in particular their collapse transition. We develop a phenomenological model in the form of a stochastic response functional that allows us to address several interesting problems such as the scaling behavior of the swollen phase and the collapse transition. For the swollen phase, we find that by choosing model parameters appropriately, our stochastic functional reduces to the one describing the relaxation dynamics near the Yang-Lee singularity edge. This corroborates that the scaling behavior of swollen branched polymers is governed by the Yang-Lee universality class as has been known for a long time. The main focus of our paper lies on the collapse transition of directed branched polymers. We show to arbitrary order in renormalized perturbation theory with epsilon expansion that this transition belongs to the same universality class as directed percolation. PMID:19905335

  4. Flow induced migration in polymer melts – Theory and simulation

    SciTech Connect

    Dorgan, John Robert Rorrer, Nicholas Andrew

    2015-04-28

    Flow induced migration, whereby polymer melts are fractionated by molecular weight across a flow field, represents a significant complication in the processing of polymer melts. Despite its long history, such phenomena remain relatively poorly understood. Here a simple analytical theory is presented which predicts the phenomena based on well-established principles of non-equilibrium thermodynamics. It is unambiguously shown that for purely viscous materials, a gradient in shear rate is needed to drive migration; for purely viscometric flows no migration is expected. Molecular scale simulations of flow migration effects in dense polymer melts are also presented. In shear flow the melts exhibit similar behavior as the quiescent case; a constant shear rate across the gap does not induce chain length based migration. In comparison, parabolic flow causes profound migration for both unentangled and entangled melts. These findings are consistent with the analytical theory. The picture that emerges is consistent with flow induced migration mechanisms predominating over competing chain degradation mechanisms.

  5. Lattice cluster theory for polymer melts with specific interactions

    NASA Astrophysics Data System (ADS)

    Xu, Wen-Sheng; Freed, Karl F.

    2014-07-01

    Despite the long-recognized fact that chemical structure and specific interactions greatly influence the thermodynamic properties of polymer systems, a predictive molecular theory that enables systematically addressing the role of chemical structure and specific interactions has been slow to develop even for polymer melts. While the lattice cluster theory (LCT) provides a powerful vehicle for understanding the influence of various molecular factors, such as monomer structure, on the thermodynamic properties of polymer melts and blends, the application of the LCT has heretofore been limited to the use of the simplest polymer model in which all united atom groups within the monomers of a species interact with a common monomer averaged van der Waals energy. Thus, the description of a compressible polymer melt involves a single van der Waals energy. As a first step towards developing more realistic descriptions to aid in the analysis of experimental data and the design of new materials, the LCT is extended here to treat models of polymer melts in which the backbone and side groups have different interaction strengths, so three energy parameters are present, namely, backbone-backbone, side group-side group, and backbone-side group interaction energies. Because of the great algebraic complexity of this extension, we retain maximal simplicity within this class of models by further specializing this initial study to models of polymer melts comprising chains with poly(n-α-olefin) structures where only the end segments on the side chains may have different, specific van der Waals interaction energies with the other united atom groups. An analytical expression for the LCT Helmholtz free energy is derived for the new model. Illustrative calculations are presented to demonstrate the degree to which the thermodynamic properties of polymer melts can be controlled by specific interactions.

  6. Lattice cluster theory for polymer melts with specific interactions

    SciTech Connect

    Xu, Wen-Sheng; Freed, Karl F.

    2014-07-28

    Despite the long-recognized fact that chemical structure and specific interactions greatly influence the thermodynamic properties of polymer systems, a predictive molecular theory that enables systematically addressing the role of chemical structure and specific interactions has been slow to develop even for polymer melts. While the lattice cluster theory (LCT) provides a powerful vehicle for understanding the influence of various molecular factors, such as monomer structure, on the thermodynamic properties of polymer melts and blends, the application of the LCT has heretofore been limited to the use of the simplest polymer model in which all united atom groups within the monomers of a species interact with a common monomer averaged van der Waals energy. Thus, the description of a compressible polymer melt involves a single van der Waals energy. As a first step towards developing more realistic descriptions to aid in the analysis of experimental data and the design of new materials, the LCT is extended here to treat models of polymer melts in which the backbone and side groups have different interaction strengths, so three energy parameters are present, namely, backbone-backbone, side group-side group, and backbone-side group interaction energies. Because of the great algebraic complexity of this extension, we retain maximal simplicity within this class of models by further specializing this initial study to models of polymer melts comprising chains with poly(n-α-olefin) structures where only the end segments on the side chains may have different, specific van der Waals interaction energies with the other united atom groups. An analytical expression for the LCT Helmholtz free energy is derived for the new model. Illustrative calculations are presented to demonstrate the degree to which the thermodynamic properties of polymer melts can be controlled by specific interactions.

  7. Additive Manufacturing and Characterization of Ultem Polymers and Composites

    NASA Technical Reports Server (NTRS)

    Chuang, Kathy C.; Grady, Joseph E.; Draper, Robert D.; Shin, Euy-Sik E.; Patterson, Clark; Santelle, Thomas D.

    2015-01-01

    The objective of this project was to conduct additive manufacturing to produce aircraft engine components by Fused Deposition Modeling (FDM), using commercially available polyetherimides - Ultem 9085 and experimental Ultem 1000 mixed with 10 percent chopped carbon fiber. A property comparison between FDM-printed and injection-molded coupons for Ultem 9085, Ultem 1000 resin and the fiber-filled composite Ultem 1000 was carried out. Furthermore, an acoustic liner was printed from Ultem 9085 simulating conventional honeycomb structured liners and tested in a wind tunnel. Composite compressor inlet guide vanes were also printed using fiber-filled Ultem 1000 filaments and tested in a cascade rig. The fiber-filled Ultem 1000 filaments and composite vanes were characterized by scanning electron microscope (SEM) and acid digestion to determine the porosity of FDM-printed articles which ranged from 25-31 percent. Coupons of Ultem 9085 and experimental Ultem 1000 composites were tested at room temperature and 400 degrees Fahrenheit to evaluate their corresponding mechanical properties.

  8. Generalized van der Waals density functional theory for nonuniform polymers

    SciTech Connect

    Patra, Chandra N.; Yethiraj, Arun

    2000-01-15

    A density functional theory is presented for the effect of attractions on the structure of polymers at surfaces. The theory treats the ideal gas functional exactly, and uses a weighted density approximation for the hard chain contribution to the excess free energy functional. The attractive interactions are treated using a van der Waals approximation. The theory is in good agreement with computer simulations for the density profiles at surfaces for a wide range of densities and temperatures, except for low polymer densities at low temperatures where it overestimates the depletion of chains from the surface. This deficiency is attributed to the neglect of liquid state correlations in the van der Waals term of the free energy functional. (c) 2000 American Institute of Physics.

  9. Manufacturing polymer/carbon nanotube composite using a novel direct process.

    PubMed

    Tran, C-D; Lucas, S; Phillips, D G; Randeniya, L K; Baughman, R H; Tran-Cong, T

    2011-04-01

    A direct process for manufacturing polymer carbon nanotube (CNT)-based composite yarns is reported. The new approach is based on a modified dry spinning method of CNT yarn and gives a high alignment of the CNT bundle structure in yarns. The aligned CNT structure was combined with a polymer resin and, after being stressed through the spinning process, the resin was cured and polymerized, with the CNT structure acting as reinforcement in the composite. Thus the present method obviates the need for special and complex treatments to align and disperse CNTs in a polymer matrix. The new process allows us to produce a polymer/CNT composite with properties that may satisfy various engineering specifications. The structure of the yarn was investigated using scanning electron microscopy coupled with a focused-ion-beam system. The tensile behavior was characterized using a dynamic mechanical analyzer. Fourier transform infrared spectrometry was also used to chemically analyze the presence of polymer on the composites. The process allows development of polymer/CNT-based composites with different mechanical properties suitable for a range of applications by using various resins. PMID:21346301

  10. Manufacturing polymer/carbon nanotube composite using a novel direct process

    NASA Astrophysics Data System (ADS)

    Tran, C.-D.; Lucas, S.; Phillips, D. G.; Randeniya, L. K.; Baughman, R. H.; Tran-Cong, T.

    2011-04-01

    A direct process for manufacturing polymer carbon nanotube (CNT)-based composite yarns is reported. The new approach is based on a modified dry spinning method of CNT yarn and gives a high alignment of the CNT bundle structure in yarns. The aligned CNT structure was combined with a polymer resin and, after being stressed through the spinning process, the resin was cured and polymerized, with the CNT structure acting as reinforcement in the composite. Thus the present method obviates the need for special and complex treatments to align and disperse CNTs in a polymer matrix. The new process allows us to produce a polymer/CNT composite with properties that may satisfy various engineering specifications. The structure of the yarn was investigated using scanning electron microscopy coupled with a focused-ion-beam system. The tensile behavior was characterized using a dynamic mechanical analyzer. Fourier transform infrared spectrometry was also used to chemically analyze the presence of polymer on the composites. The process allows development of polymer/CNT-based composites with different mechanical properties suitable for a range of applications by using various resins.

  11. Solvation of polymers as mutual association. I. General theory

    NASA Astrophysics Data System (ADS)

    Dudowicz, Jacek; Freed, Karl F.; Douglas, Jack F.

    2013-04-01

    A Flory-Huggins (FH) type lattice theory of self-assembly is generalized to describe the equilibrium solvation of long polymer chains B by small solvent molecules A. Solvation is modeled as a thermally reversible mutual association between the polymer and a relatively low molar mass solvent. The FH Helmholtz free energy F is derived for a mixture composed of the A and B species and the various possible mutual association complexes AiB, and F is then used to generate expressions for basic thermodynamic properties of solvated polymer solutions, including the size distribution of the solvated clusters, the fraction of solvent molecules contained in solvated states (an order parameter for solvation), the specific heat (which exhibits a maximum at the solvation transition), the second and the third osmotic virial coefficients, and the boundaries for phase stability of the mixture. Special attention is devoted to the analysis of the "entropic" contribution χs to the FH interaction parameter χ of polymer solutions, both with and without associative interactions. The entropic χs parameter arises from correlations associated with polymer chain connectivity and disparities in molecular structure between the components of the mixture. Our analysis provides the first explanation of the longstanding enigma of why χs for polymer solutions significantly exceeds χs for binary polymer blends. Our calculations also reveal that χs becomes temperature dependent when interactions are strong, in sharp contrast to models currently being used for fitting thermodynamic data of associating polymer-solvent mixtures, where χs is simply assumed to be an adjustable constant based on experience with solutions of homopolymers in nonassociating solvents.

  12. Theories of surface-driven segregation in polymer fluids

    NASA Astrophysics Data System (ADS)

    Wong, Ka Yiu

    1998-10-01

    Three polymer interfacial systems-thin films of diblock copolymer melts, polymer blends near surfaces, and surface segregation of athermal polymer blends-are studied by density functional theory. We analyze the weak-segregation, thermodynamic predictions of a simple mean-field model of diblock copolymer melts sandwiched between surfaces that interact weakly with melts. These films may not exhibit a phase transition although the segregation that develops within them resembles ordering in the bulk. When transitions occur, they result from a competition between surface and bulk effects and have no bulk analogue. Thin films confined by identical surfaces or surfaces having equal-in-magnitude but opposite affinities for the monomers may exhibit first- and second-order transitions when the melt-surface interactions are small. Second-order transitions do not occur in films with large surface affinities. The instabilities that lead to the second-order transitions in films disappear with increases in the film thickness. We also investigate the long-wavelength features of near- surface composition profiles of monomers in a binary, symmetric blend with an external field gradient expansion. The gradient expansion includes information about correlations of polymer chains with the surface. Relative to simpler theories of polymer-surface adsorption, our theory predicts a small increase of the interfacial width. We illustrate a derivation of a surface-boundary condition on the composition profile directly from the monomer-surface Hamiltonian. This boundary condition, when combined with our density functional analysis, leads to first-order wetting transitions. Finally, our work on surface segregation of athermal blends is presented. We study the effect on surface segregation due to disparity in molecular weights, stiffness of polymer chains, and sizes of the monomers. Our results suggest that disparity in molecular weights do not lead to a profound surface segregation. In the study

  13. A Fully Non-Metallic Gas Turbine Engine Enabled by Additive Manufacturing Part I: System Analysis, Component Identification, Additive Manufacturing, and Testing of Polymer Composites

    NASA Technical Reports Server (NTRS)

    Grady, Joseph E.; Haller, William J.; Poinsatte, Philip E.; Halbig, Michael C.; Schnulo, Sydney L.; Singh, Mrityunjay; Weir, Don; Wali, Natalie; Vinup, Michael; Jones, Michael G.; Patterson, Clark; Santelle, Tom; Mehl, Jeremy

    2015-01-01

    The research and development activities reported in this publication were carried out under NASA Aeronautics Research Institute (NARI) funded project entitled "A Fully Nonmetallic Gas Turbine Engine Enabled by Additive Manufacturing." The objective of the project was to conduct evaluation of emerging materials and manufacturing technologies that will enable fully nonmetallic gas turbine engines. The results of the activities are described in three part report. The first part of the report contains the data and analysis of engine system trade studies, which were carried out to estimate reduction in engine emissions and fuel burn enabled due to advanced materials and manufacturing processes. A number of key engine components were identified in which advanced materials and additive manufacturing processes would provide the most significant benefits to engine operation. The technical scope of activities included an assessment of the feasibility of using additive manufacturing technologies to fabricate gas turbine engine components from polymer and ceramic matrix composites, which were accomplished by fabricating prototype engine components and testing them in simulated engine operating conditions. The manufacturing process parameters were developed and optimized for polymer and ceramic composites (described in detail in the second and third part of the report). A number of prototype components (inlet guide vane (IGV), acoustic liners, engine access door) were additively manufactured using high temperature polymer materials. Ceramic matrix composite components included turbine nozzle components. In addition, IGVs and acoustic liners were tested in simulated engine conditions in test rigs. The test results are reported and discussed in detail.

  14. Electric poling-assisted additive manufacturing process for PVDF polymer-based piezoelectric device applications

    NASA Astrophysics Data System (ADS)

    Lee, ChaBum; Tarbutton, Joshua A.

    2014-09-01

    This paper presents a new additive manufacturing (AM) process to directly and continuously print piezoelectric devices from polyvinylidene fluoride (PVDF) polymeric filament rods under a strong electric field. This process, called ‘electric poling-assisted additive manufacturing or EPAM, combines AM and electric poling processes and is able to fabricate free-form shape piezoelectric devices continuously. In this process, the PVDF polymer dipoles remain well-aligned and uniform over a large area in a single design, production and fabrication step. During EPAM process, molten PVDF polymer is simultaneously mechanically stresses in-situ by the leading nozzle and electrically poled by applying high electric field under high temperature. The EPAM system was constructed to directly print piezoelectric structures from PVDF polymeric filament while applying high electric field between nozzle tip and printing bed in AM machine. Piezoelectric devices were successfully fabricated using the EPAM process. The crystalline phase transitions that occurred from the process were identified by using the Fourier transform infrared spectroscope. The results indicate that devices printed under a strong electric field become piezoelectric during the EPAM process and that stronger electric fields result in greater piezoelectricity as marked by the electrical response and the formation of sharper peaks at the polar β crystalline wavenumber of the PVDF polymer. Performing this process in the absence of an electric field does not result in dipole alignment of PVDF polymer. The EPAM process is expected to lead to the widespread use of AM to fabricate a variety of piezoelectric PVDF polymer-based devices for sensing, actuation and energy harvesting applications with simple, low cost, single processing and fabrication step.

  15. Studies in process modeling, design, monitoring, and control, with applications to polymer composites manufacturing

    NASA Astrophysics Data System (ADS)

    Srinivasagupta, Deepak

    2002-01-01

    High material and manufacturing costs have hindered the introduction of advanced polymer composite materials into mainstream civilian applications such as automotive. Even though high-fidelity models for several polymer composite manufacturing processes have become available over the past several years and offer significant benefits in manufacturing cost reduction, concerns about their inflexibility and maintenance has adversely affected their widespread usage. This research seeks to advance process modeling and design in polymer composites manufacturing to address these concerns. Other more general issues in measurement validation and distributed control are also addressed. Using a rigorous 3-D model of the injected pultrusion (IP) process validated recently, an algorithm was developed for process and equipment design with integrated economic, operability and environmental considerations. The optimum design promised enhanced throughput as well as reduction in the time and expenses of the current purely experimental approaches. Scale-up issues in IP were analyzed, and refinements to overcome some drawbacks in the model were suggested. The process model was then extended to simulate the co-injection resin transfer molding (CIRTM) process used for manufacture of foam-core sandwich composites. A 1-D isothermal model for real-time control was also developed. Process optimization using these models and experimental parametric studies increased the debond fracture toughness of sandwiches by 78% over current technology. To ensure the availability of validated measurements from process instrumentation, a novel in-situ sensor modeling approach to sensor validation was proposed. Both active and passive, time and frequency domain techniques were developed, and experimentally verified using temperature and flow sensors. A model-based dynamic estimator to predict the true measurement online was also validated. The effect of network communication delay on stability and control

  16. An overview on the effect of manufacturing on the shock response of polymers

    NASA Astrophysics Data System (ADS)

    Kister, Guillaume; Wood, David; Appleby-Thomas, Gareth; Roberts, Andrew; Leighs, James; Goff, Michael; Hameed, Amer

    2013-06-01

    Polymers are widely employed in areas as diverse as consumer goods and explosives (matrix materials). The consequent commercial interest has led to a continual drive to improve material properties - e.g. via either manufacturing techniques or more fundamental improvements in the understanding of the underlying chemistry. It has been shown previously that chemical compositions can affect the shock profile of the polymer Poly-Methyl Methacrylate (PMMA). To this end the composition will change over time as new formulations are brought to market, for example due to the inclusion of additives that will increase the lifetime of the product. Significantly such changes may not affect the material properties at lower strain rates. At the higher strain rates these subtle difference can lead to larger discrepancies in the shock profiles. In this study comparisons of PMMA have been made between newly sourced and ``legacy'' material studied previously in the literature.

  17. Microscopic theory for dynamics in entangled polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Yamamoto, Umi

    New microscopic theories for describing dynamics in polymer nanocomposites are developed and applied. The problem is addressed from two distinct perspectives and using two different theoretical approaches. The first half of this dissertation studies the long-time and intermediate-time dynamics of nanoparticles in entangled and unentangled polymer melts for dilute particle concentrations. Using a combination of mode-coupling, Brownian motion, and polymer physics ideas, the nanoparticle long-time diffusion coefficients is formulated in terms of multiple length-scales, packing microstructures, and spatially-resolved polymer density fluctuation dynamics. The key motional mechanism is described via the parallel relaxation of the force exerted on the particle controlled by collective polymer constraint-release and the particle self-motion. A sharp but smooth crossover from the hydrodynamic to the non-hydrodynamic regime is predicted based on the Stokes-Einstein violation ratio as a function of all the system variables. Quantitative predictions are made for the recovery of the Stokes-Einstein law, and the diffusivity in the crossover regime agrees surprisingly well with large-scale molecular dynamics simulations for all particle sizes and chain lengths studied. The approach is also extended to address intermediate-time anomalous transport of a single nanoparticle and two-particle relative diffusion. The second half of this dissertation focuses on developing a novel dynamical theory for a liquid of infinitely-thin rods in the presence of hard spherical obstacles, aiming at a technical and conceptual extension of the existing paradigm for entangled polymer dynamics. As a fundamental theoretical development, the two-component generalization of a first-principles dynamic meanfield approach is presented. The theory enforces inter-needle topological uncrossability and needlesphere impenetrability in a unified manner, leading to a generalized theory of entanglements that

  18. Feasibility study of custom manufacturing methods of ionic polymer-metal composite sensors

    NASA Astrophysics Data System (ADS)

    Nelson, Shelby E.

    The ability to create an ion exchange membrane with any shape or thickness through custom manufacturing techniques is highly desirable in ionic polymer-metal composite (IPMC) research. This is caused by the poor selection and limited availability of certain thicknesses of commercial ion exchange membranes. The objective of this study is to determine the feasibility of manufacturing custom ion exchange membranes for IPMC sensors. The manufacturing methods used in this study are extrusion, injection molding, and hot pressing. A commercial membrane from Golden Energy Fuel Cells (GEFC) is used as a comparison. After the membranes are fabricated, certain properties of the membranes are tested throughout each processing stage to determine if they are suitable to be developed into IPMCs. The three processing stages are pre-activation, activation (hydrated and dehydrated), and IPMC. It was observed that the stiffness of the membranes increased from pre-activation to activation and decreased from activation to IPMC. A more flexible membrane in an IPMC allows for larger cation displacement within the membrane. The extruded and injection molded membranes showed the most potential with having the lowest stiffness of all the samples; however, they were not able to be made into IPMCs due to repeated membrane failures in the primary plating process. Gas accumulated between the layers that formed in the membranes due to the extrusion and injection molding cooling process during manufacturing. The hot pressed membrane was the only custom manufactured membrane to be fully processed into an IPMC. The hot pressed and GEFC IPMC sensors were operated at 1 Hz, 5 Hz, and 10 Hz frequencies with the GEFC IPMC producing the strongest output voltage signal. While the extruded and injection molded membranes showed potential to become IPMCs with their high water uptake percentage, high ion exchange capacity, and low stiffness, more development is needed within the manufacturing process to make

  19. Theory of exciton transfer and diffusion in conjugated polymers

    SciTech Connect

    Barford, William; Tozer, Oliver Robert

    2014-10-28

    We describe a theory of Förster-type exciton transfer between conjugated polymers. The theory is built on three assumptions. First, we assume that the low-lying excited states of conjugated polymers are Frenkel excitons coupled to local normal modes, and described by the Frenkel-Holstein model. Second, we assume that the relevant parameter regime is ℏω < J, i.e., the adiabatic regime, and thus the Born-Oppenheimer factorization of the electronic and nuclear degrees of freedom is generally applicable. Finally, we assume that the Condon approximation is valid, i.e., the exciton-polaron wavefunction is essentially independent of the normal modes. The resulting expression for the exciton transfer rate has a familiar form, being a function of the exciton transfer integral and the effective Franck-Condon factors. The effective Franck-Condon factors are functions of the effective Huang-Rhys parameters, which are inversely proportional to the chromophore size. The Born-Oppenheimer expressions were checked against DMRG calculations, and are found to be within 10% of the exact value for a tiny fraction of the computational cost. This theory of exciton transfer is then applied to model exciton migration in conformationally disordered poly(p-phenylene vinylene). Key to this modeling is the assumption that the donor and acceptor chromophores are defined by local exciton ground states (LEGSs). Since LEGSs are readily determined by the exciton center-of-mass wavefunction, this theory provides a quantitative link between polymer conformation and exciton migration. Our Monte Carlo simulations indicate that the exciton diffusion length depends weakly on the conformation of the polymer, with the diffusion length increasing slightly as the chromophores became straighter and longer. This is largely a geometrical effect: longer and straighter chromophores extend over larger distances. The calculated diffusion lengths of ∼10 nm are in good agreement with experiment. The spectral

  20. Surfactant self-assembly in oppositely charged polymer networks. Theory.

    PubMed

    Hansson, Per

    2009-10-01

    The interaction of ionic surfactants with polyion networks of opposite charge in an aqueous environment is analyzed theoretically by applying a recent theory of surfactant ion-polyion complex salts (J. Colloid. Int. Sci. 2009, 332, 183). The theory takes into account attractive and repulsive polyion-mediated interactions between the micelles, the deformation of the polymer network, the mixing of micelles, polyion chains, and simple ions with water, and the hydrophobic free energy at the micelle surface. The theory is used to calculate binding isotherms, swelling isotherms, surfactant aggregation numbers, compositions of complexes,and phase structure under various conditions. Factors controlling the gel volume transition and conditions for core/shell phase coexistence are investigated in detail, as well as the influence of salt. In particular, the interplay between electrostatic and elastic interactions is highlighted. Results from theory are compared with experimental data reported in the literature. The agreement is found to be semiquantitative or qualitative. The theory explains both the discrete volume transition observed in systems where the surfactant is in excess over the polyion and the core/shell phase coexistence in systems where the polyion is in excess. PMID:19728696

  1. Theory of optical transitions in conjugated polymers. II. Real systems

    NASA Astrophysics Data System (ADS)

    Marcus, Max; Tozer, Oliver Robert; Barford, William

    2014-10-01

    The theory of optical transitions developed in Barford and Marcus ["Theory of optical transitions in conjugated polymers. I. Ideal systems," J. Chem. Phys. 141, 164101 (2014)] for linear, ordered polymer chains is extended in this paper to model conformationally disordered systems. Our key result is that in the Born-Oppenheimer regime the emission intensities are proportional to S(1)/⟨IPR⟩, where S(1) is the Huang-Rhys parameter for a monomer. ⟨IPR⟩ is the average inverse participation ratio for the emitting species, i.e., local exciton ground states (LEGSs). Since the spatial coherence of LEGSs determines the spatial extent of chromophores, the significance of this result is that it directly relates experimental observables to chromophore sizes (where ⟨IPR⟩ is half the mean chromophore size in monomer units). This result is independent of the chromophore shape, because of the Born-Oppenheimer factorization of the many body wavefunction. We verify this prediction by density matrix renormalization group (DMRG) calculations of the Frenkel-Holstein model in the adiabatic limit for both linear, disordered chains and for coiled, ordered chains. We also model optical spectra for poly(p-phenylene) and poly(p-phenylene-vinylene) oligomers and polymers. For oligomers, we solve the fully quantized Frenkel-Holstein model via the DMRG method. For polymers, we use the much simpler method of solving the one-particle Frenkel model and employ the Born-Oppenheimer expressions relating the effective Franck-Condon factor of a chromophore to its inverse participation ratio. We show that increased disorder decreases chromophore sizes and increases the inhomogeneous broadening, but has a non-monotonic effect on transition energies. We also show that as planarizing the polymer chain increases the exciton band width, it causes the chromophore sizes to increase, the transition energies to decrease, and the broadening to decrease. Finally, we show that the absorption spectra are

  2. Mesoscale 3D manufacturing: varying focusing conditions for efficient direct laser writing of polymers

    NASA Astrophysics Data System (ADS)

    Jonušauskas, Linas; Malinauskas, Mangirdas

    2014-05-01

    In this paper, we report a novel approach for efficient fabrication of mesoscale polymer 3D microstructures. It is implemented by direct laser writing varying exposure beam focusing conditions. By carefully optimizing the fabrication parameters (laser intensity, scanning velocity/exposure time, changing objective lens) complex 3D geometries of the microstructures can be obtained rapidly. Additionally, we demonstrate this without the use of the photoinitiator as photosensitizer doped in the pre-polymer material (SZ2080). At femtosecond pulsed irradiation ~TW/cm² intensities the localized free radical polymerization is achieved via avalanche induced bond braking. Such microstructures have unique biocompatibility and optical transparency as well as optical damage threshold value. By creating the bulk part of the structure using low-NA (0.45) objective and subsequently fabricating the fine features using oil immersion high-NA (1.4) objective the manufacturing time is reduced dramatically (30x is demonstrated). Using this two objective method a prototype of functional microdevice was produced: 80 and 85 µm diameter microfluidic tubes with the fine filter consisting of 4 µm period grating structure that has 400 nm wide threads, which corresponds to a feature precision aspect ratio of ~200. Therefore, such method has great potential as a polymer fabrication tool for mesoscale optical, photonic and biomedical applications as well as highly integrated 3D µ-systems. Furthermore, the proposed approach is not limited to lithography and can be implemented in a more general type of laser writing, such as inscription within transparent materials or substractive manufacturing by ablation.

  3. Magnetically anisotropic additive for scalable manufacturing of polymer nanocomposite: iron-coated carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yamamoto, Namiko; Manohara, Harish; Platzman, Ellen

    2016-02-01

    Novel nanoparticles additives for polymer nanocomposites were prepared by coating carbon nanotubes (CNTs) with ferromagnetic iron (Fe) layers, so that their micro-structures can be bulk-controlled by external magnetic field application. Application of magnetic fields is a promising, scalable method to deliver bulk amount of nanocomposites while maintaining organized nanoparticle assembly throughout the uncured polymer matrix. In this work, Fe layers (˜18 nm thick) were deposited on CNTs (˜38 nm diameter and ˜50 μm length) to form thin films with high aspect ratio, resulting in a dominance of shape anisotropy and thus high coercivity of ˜50-100 Oe. The Fe-coated CNTs were suspended in water and applied with a weak magnetic field of ˜75 G, and yet preliminary magnetic assembly was confirmed. Our results demonstrate that the fabricated Fe-coated CNTs are magnetically anisotropic and effectively respond to magnetic fields that are ˜103 times smaller than other existing work (˜105 G). We anticipate this work will pave the way for effective property enhancement and bulk application of CNT-polymer nanocomposites, through controlled micro-structure and scalable manufacturing.

  4. Communication: Theory of melt-memory in polymer crystallization

    NASA Astrophysics Data System (ADS)

    Muthukumar, M.

    2016-07-01

    Details of crystallization processes of a polymer at the crystallization temperature Tc from its melt kept initially at the melt temperature Tm depend profoundly on the nature of the initial melt state and often are accompanied by memory effects. This phenomenon is in contrast to small molecular systems where the supercooling (Tm0-Tc), with Tm0 being the equilibrium melting temperature, and not (Tm - Tc), determines the nature of crystallization. In addressing this five-decade old puzzle of melt-memory in polymer crystallization, we present a theory to describe melt-memory effects, by invoking an intermediate inhomogeneous melt state in the pathway between the melt and crystalline states. Using newly introduced dissolution temperature T10 for the inhomogeneous melt state and the transition temperature Tt0 for the transition between the inhomogeneous melt and crystalline states, analytical formulas are derived for the nucleation rate as a function of the melt temperature. The theory is general to address different kinds of melt-memory effects depending on whether Tm is higher or lower than Tm0. The derived results are in qualitative agreement with known experimental data, while making predictions for further experiments on melt-memory.

  5. Communication: Theory of melt-memory in polymer crystallization.

    PubMed

    Muthukumar, M

    2016-07-21

    Details of crystallization processes of a polymer at the crystallization temperature Tc from its melt kept initially at the melt temperature Tm depend profoundly on the nature of the initial melt state and often are accompanied by memory effects. This phenomenon is in contrast to small molecular systems where the supercooling (Tm (0)-Tc), with Tm (0) being the equilibrium melting temperature, and not (Tm - Tc), determines the nature of crystallization. In addressing this five-decade old puzzle of melt-memory in polymer crystallization, we present a theory to describe melt-memory effects, by invoking an intermediate inhomogeneous melt state in the pathway between the melt and crystalline states. Using newly introduced dissolution temperature T1 (0) for the inhomogeneous melt state and the transition temperature Tt (0) for the transition between the inhomogeneous melt and crystalline states, analytical formulas are derived for the nucleation rate as a function of the melt temperature. The theory is general to address different kinds of melt-memory effects depending on whether Tm is higher or lower than Tm (0). The derived results are in qualitative agreement with known experimental data, while making predictions for further experiments on melt-memory. PMID:27448866

  6. Manufacture of porous biodegradable polymer conduits by an extrusion process for guided tissue regeneration

    NASA Technical Reports Server (NTRS)

    Widmer, M. S.; Gupta, P. K.; Lu, L.; Meszlenyi, R. K.; Evans, G. R.; Brandt, K.; Savel, T.; Gurlek, A.; Patrick, C. W. Jr; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

    1998-01-01

    We have fabricated porous, biodegradable tubular conduits for guided tissue regeneration using a combined solvent casting and extrusion technique. The biodegradable polymers used in this study were poly(DL-lactic-co-glycolic acid) (PLGA) and poly(L-lactic acid) (PLLA). A polymer/salt composite was first prepared by a solvent casting process. After drying, the composite was extruded to form a tubular construct. The salt particles in the construct were then leached out leaving a conduit with an open-pore structure. PLGA was studied as a model polymer to analyze the effects of salt weight fraction, salt particle size, and processing temperature on porosity and pore size of the extruded conduits. The porosity and pore size were found to increase with increasing salt weight fraction. Increasing the salt particle size increased the pore diameter but did not affect the porosity. High extrusion temperatures decreased the pore diameter without altering the porosity. Greater decrease in molecular weight was observed for conduits manufactured at higher temperatures. The mechanical properties of both PLGA and PLLA conduits were tested after degradation in vitro for up to 8 weeks. The modulus and failure strength of PLLA conduits were approximately 10 times higher than those of PLGA conduits. Failure strain was similar for both conduits. After degradation for 8 weeks, the molecular weights of the PLGA and PLLA conduits decreased to 38% and 43% of the initial values, respectively. However, both conduits maintained their shape and did not collapse. The PLGA also remained amorphous throughout the time course, while the crystallinity of PLLA increased from 5.2% to 11.5%. The potential of seeding the conduits with cells for transplantation or with biodegradable polymer microparticles for drug delivery was also tested with dyed microspheres. These porous tubular structures hold great promise for the regeneration of tissues which require tubular scaffolds such as peripheral nerve

  7. Theory of optical transitions in conjugated polymers. I. Ideal systems

    NASA Astrophysics Data System (ADS)

    Barford, William; Marcus, Max

    2014-10-01

    We describe a theory of linear optical transitions in conjugated polymers. The theory is based on three assumptions. The first is that the low-lying excited states of conjugated polymers are Frenkel excitons coupled to local normal modes, described by the Frenkel-Holstein model. Second, we assume that the relevant parameter regime is ℏω ≪ J, i.e., the adiabatic regime, and thus the Born-Oppenheimer factorization of the electronic and nuclear degrees of freedom is generally applicable. Finally, we assume that the Condon approximation is valid, i.e., the exciton-polaron wavefunction is essentially independent of the normal modes. Using these assumptions we derive an expression for an effective Huang-Rhys parameter for a chain (or chromophore) of N monomers, given by S(N) = S(1)/IPR, where S(1) is the Huang-Rhys parameter for an isolated monomer. IPR is the inverse participation ratio, defined by IPR = (∑n|Ψn|4)-1, where Ψn is the exciton center-of-mass wavefunction. Since the IPR is proportional to the spread of the exciton center-of-mass wavefunction, this is a key result, as it shows that S(N) decreases with chain length. As in molecules, in a polymer S(N) has two interpretations. First, ℏωS(N) is the relaxation energy of an excited state caused by its coupling to the normal modes. Second, S(N) appears in the definition of an effective Franck-Condon factor, F0v(N) = S(N)vexp ( - S(N))/v! for the vth vibronic manifold. We show that the 0 - 0 and 0 - 1 optical intensities are proportional to F00(N) and F01(N), respectively, and thus the ratio of the 0 - 1 to 0 - 0 absorption and emission intensities are proportional to S(N). These analytical results are checked by extensive DMRG calculations and found to be generally valid, particularly for emission. However, for large chain lengths higher-lying quasimomentum exciton states become degenerate with the lowest vibrational excitation of the lowest exciton state. When this happens there is mixing of the

  8. Application of TRIZ Theory in Patternless Casting Manufacturing Technique

    NASA Astrophysics Data System (ADS)

    Yang, Weidong; Gan, Dequan; Jiang, Ping; Tian, Yumei

    The ultimate goal of Patternless Casting Manufacturing (referred to as PCM) is how to obtain the casts by casting the sand mold directly. In the previous PCM, the resin content of sand mold is much higher than that required by traditional resin sand, so the casts obtained are difficult to be sound and qualified products, which limits the application of this technique greatly. In this paper, the TRIZ algorithm is introduced to the innovation process in PCM systematically.

  9. Collapse transition of randomly branched polymers: renormalized field theory.

    PubMed

    Janssen, Hans-Karl; Stenull, Olaf

    2011-05-01

    We present a minimal dynamical model for randomly branched isotropic polymers, and we study this model in the framework of renormalized field theory. For the swollen phase, we show that our model provides a route to understand the well-established dimensional-reduction results from a different angle. For the collapse θ transition, we uncover a hidden Becchi-Rouet-Stora supersymmetry, signaling the sole relevance of tree configurations. We correct the long-standing one-loop results for the critical exponents, and we push these results on to two-loop order. For the collapse θ' transition, we find a runaway of the renormalization group flow, which lends credence to the possibility that this transition is a fluctuation-induced first-order transition. Our dynamical model allows us to calculate for the first time the fractal dimension of the shortest path on randomly branched polymers in the swollen phase as well as at the collapse transition and related fractal dimensions. PMID:21728509

  10. Damage initiation, progression and failure of polymer matrix composites due to manufacturing induced defects

    NASA Astrophysics Data System (ADS)

    Chowdhury, Khairul Alam

    In polymer matrix composites (PMCs) manufacturing processes can induce defects, e.g., voids, fiber misalignment, irregular fiber distribution in the cross-section and broken fibers. The effects of such defects can be beneficial or deleterious depending on whether they cause failure suppression or enhancement by localized deformation processes e.g., crazing, shear yielding and fiber-matrix debonding. In this study, a computational approach is formulated and implemented to develop solutions for general boundary-value problems for PMC microstructures that accounts for micromechanics-based constitutive relations including fine scale mechanisms of material failure. The defects considered are voids, and the microstructure is explicitly represented by a distribution of fibers and voids embedded in a polymer matrix. Fiber is modeled as a linearly elastic material while the polymer matrix is modeled as an elastic-viscoplastic material. Two distinct models for the matrix behavior are implemented: (i) Drucker-Prager type Bodner model that accounts for rate and pressure-sensitivity, and (ii) improved macromolecular constitutive model that also accounts for temperature dependence, small-strain softening and large-strain hardening. Damage is simulated by the Gearing-Anand craze model as a reference model and by a new micromechanical craze model, developed to account for craze initiation, growth and breakdown. Critical dilatational energy density criterion is utilized to predict fiber-matrix debonding through cavitation induced matrix cracking. An extensive parametric study is conducted in which the roles of void shape, size and distribution relative to fiber in determining damage initiation and evolution are investigated under imposed temperature and strain rate conditions. Results show there are significant effects of voids on microstructural damage as well as on the overall deformational and failure response of composites.

  11. Polymer/Silicate Nanocomposites Used to Manufacture Gas Storage Tanks With Reduced Permeability

    NASA Technical Reports Server (NTRS)

    Campbell, Sandi G.; Johnston, Chris

    2004-01-01

    Over the past decade, there has been considerable research in the area of polymer-layered silicate nanocomposites. This research has shown that the dispersion of small amounts of an organically modified layered silicate improves the polymer strength, modulus, thermal stability, and barrier properties. There have been several reports on the dispersion of layered silicates in an epoxy matrix. Potential enhancements to the barrier properties of epoxy/silicate nanocomposites make this material attractive for low permeability tankage. Polymer matrix composites (PMCs) have several advantages for cryogenic storage tanks. They are lightweight, strong, and stiff; therefore, a smaller fraction of a vehicle's potential payload capacity is used for propellant storage. Unfortunately, the resins typically used to make PMC tanks have higher gas permeability than metals. This can lead to hydrogen loss through the body of the tank instead of just at welds and fittings. One approach to eliminate this problem is to build composite tanks with thin metal liners. However, although these tanks provide good permeability performance, they suffer from a substantial mismatch in the coefficient of thermal expansion, which can lead to failure of the bond between the liner and the body of the tank. Both problems could be addressed with polymersilicate nanocomposites, which exhibit reduced hydrogen permeability, making them potential candidates for linerless PMC tanks. Through collaboration with Northrop Grumman and Michigan State University, nanocomposite test tanks were manufactured for the NASA Glenn Research Center, and the helium permeability was measured. An organically modified silicate was prepared at Michigan State University and dispersed in an epoxy matrix (EPON 826/JeffamineD230). The epoxy/silicate nanocomposites contained either 0 or 5 wt% of the organically modified silicate. The tanks were made by filament winding carbon fibers with the nanocomposite resin. Helium permeability

  12. Analytic liquid-state theory of the interactions between colloids mediated by reversibly adsorbed polymers.

    PubMed

    Chervanyov, A I

    2014-12-28

    We develop an analytic liquid-state theory of the effective interactions induced by reversibly adsorbing polymers, acting between colloids immersed in a polymer melt. This theory is based on the polymer reference interaction site model that has no restrictions with respect to the density of the polymer system and colloid-to-polymer size ratio. By making use of the developed theory, we calculate the potential of the polymer mediated interactions as a function of the colloid radius, strength and range of the adsorption potential, and the polymer density. In addition, we investigate the behavior of the second virial coefficient as a function of the polymer density in both the colloid and nano-particle limits. We found out that the presence of the adsorption interactions significantly changes the polymer mediated forces relative to the case of the pure entropic depletion interactions, showing most pronounced difference in the case of large polymer densities and small colloid-to-polymer size ratios. The significance of the above differences is determined by the relation between the range of the adsorption potential and polymer correlation length. PMID:25554175

  13. Theory of optical transitions in conjugated polymers. I. Ideal systems

    SciTech Connect

    Barford, William; Marcus, Max

    2014-10-28

    We describe a theory of linear optical transitions in conjugated polymers. The theory is based on three assumptions. The first is that the low-lying excited states of conjugated polymers are Frenkel excitons coupled to local normal modes, described by the Frenkel-Holstein model. Second, we assume that the relevant parameter regime is ℏω ≪ J, i.e., the adiabatic regime, and thus the Born-Oppenheimer factorization of the electronic and nuclear degrees of freedom is generally applicable. Finally, we assume that the Condon approximation is valid, i.e., the exciton-polaron wavefunction is essentially independent of the normal modes. Using these assumptions we derive an expression for an effective Huang-Rhys parameter for a chain (or chromophore) of N monomers, given by S(N) = S(1)/IPR, where S(1) is the Huang-Rhys parameter for an isolated monomer. IPR is the inverse participation ratio, defined by IPR = (∑{sub n}|Ψ{sub n}|{sup 4}){sup −1}, where Ψ{sub n} is the exciton center-of-mass wavefunction. Since the IPR is proportional to the spread of the exciton center-of-mass wavefunction, this is a key result, as it shows that S(N) decreases with chain length. As in molecules, in a polymer S(N) has two interpretations. First, ℏωS(N) is the relaxation energy of an excited state caused by its coupling to the normal modes. Second, S(N) appears in the definition of an effective Franck-Condon factor, F{sub 0v}(N) = S(N){sup v}exp ( − S(N))/v! for the vth vibronic manifold. We show that the 0 − 0 and 0 − 1 optical intensities are proportional to F{sub 00}(N) and F{sub 01}(N), respectively, and thus the ratio of the 0 − 1 to 0 − 0 absorption and emission intensities are proportional to S(N). These analytical results are checked by extensive DMRG calculations and found to be generally valid, particularly for emission. However, for large chain lengths higher-lying quasimomentum exciton states become degenerate with the lowest vibrational excitation of the

  14. Polymer brushes in cylindrical pores: Simulation versus scaling theory

    NASA Astrophysics Data System (ADS)

    Dimitrov, D. I.; Milchev, A.; Binder, K.

    2006-07-01

    The structure of flexible polymers endgrafted in cylindrical pores of diameter D is studied as a function of chain length N and grafting density σ, assuming good solvent conditions. A phenomenological scaling theory, describing the variation of the linear dimensions of the chains with σ, is developed and tested by molecular dynamics simulations of a bead-spring model. Different regimes are identified, depending on the ratio of D to the size of a free polymer N3/5. For D >N3/5 a crossover occurs for σ =σ*=N-6/5 from the "mushroom" behavior (Rgx=Rgy=Rgz=N3/5) to the behavior of a flat brush (Rgz=σ1/3N,Rgx=Rgy=σ-1/12N1/2), until at σ**=(D /N)3 a crossover to a compressed state of the brush, [Rgz=D,Rgx=Rgy=(N3D /4σ)1/8theories is given. In particular, it is shown that for large D the brush height is an increasing function of D-1.

  15. LOW-COST COMPOSITES IN VEHICLE MANUFACTURE - Natural-fiber-reinforced polymer composites in automotive applications.

    SciTech Connect

    Holbery, Jim; Houston, Dan

    2006-11-01

    In the last decade, natural fiber composites have experienced rapid growth in the European automotive market, and this trend appears to be global in scale, provided the cost and performance is justified against competing technologies. However, mass reduction, recyclability, and performance requirements can be met today by competing systems such as injection-molded unreinforced thermoplastics; natural fiber composites will continue to expand their role in automotive applications only if such technical challenges as moisture stability, fiber-polymer interface compatibility, and consistent, repeatable fiber sources are available to supply automotive manufacturers. Efforts underway by Tier I and II automotive suppliers to explore hybrid glass-natural fiber systems, as well as applications that exploit such capabilities as natural fiber sound dampening characteristics, could very well have far-reaching effects. In addition, the current development underway of bio-based resins such as Polyhydroxyalkanoate (PHA) biodegradable polyesters and bio-based polyols could provide fully bio-based composite options to future automotive designers. In short, the development of the natural fiber composite market would make a positive impact on farmers and small business owners on a global scale, reduce US reliance on foreign oil, improve environmental quality through the development of a sustainable resource supply chain, and achieve a better CO2 balance over the vehicle?s lifetime with near-zero net greenhouse gas emissions.

  16. Manufacturing of ionic polymer-metal composites (IPMCs) that can actuate into complex curves

    NASA Astrophysics Data System (ADS)

    Stoimenov, Boyko L.; Rossiter, Jonathan M.; Mukai, Toshiharu

    2007-04-01

    Ionic polymer-metal composites (IPMC) are soft actuators with potential applications in the fields of medicine and biologically inspired robotics. Typically, an IPMC bends with approximately constant curvature when voltage is applied to it. More complex shapes were achieved in the past by pre-shaping the actuator or by segmentation and separate actuation of each segment. There are many applications for which fully independent control of each segment of the IPMC is not required and the use of external wiring is objectionable. In this paper we propose two key elements needed to create an IPMC, which can actuate into a complex curve. The first is a connection between adjacent segments, which enables opposite curvature. This can be achieved by reversing the polarity applied on each side of the IPMC, for example by a through-hole connection. The second key element is a variable curvature segment. The segment is designed to bend with any fraction of its full bending ability under given electrical input by changing the overlap of opposite charge electrodes. We demonstrated the usefulness of these key elements in two devices. One is a bi-stable buckled IPMC beam, also used as a building block in a linear actuator device. The other one is an IPMC, actuating into an S-shaped curve with gradually increasing curvature near the ends. The proposed method of manufacturing holds promise for a wide range of new applications of IPMCs, including applications in which IPMCs are used for sensing.

  17. Additive Manufacturing of a Photo-Cross-Linkable Polymer via Direct Melt Electrospinning Writing for Producing High Strength Structures.

    PubMed

    Chen, Fei; Hochleitner, Gernot; Woodfield, Tim; Groll, Juergen; Dalton, Paul D; Amsden, Brian G

    2016-01-11

    Melt electrospinning writing (MEW) is an emerging additive manufacturing technique that enables the design and fabrication of micrometer-thin fibrous scaffolds made of biocompatible and biodegradable polymers. By using a computer-aided deposition process, a unique control over pore size and interconnectivity of the resulting scaffolds is achieved, features highly interesting for tissue engineering applications. However, MEW has been mainly used to process low melting point thermoplastics such as poly(ε-caprolactone). Since this polymer exhibits creep and a reduction in modulus upon hydration, we manufactured scaffolds of poly(L-lactide-co-ε-caprolactone-co-acryloyl carbonate) (poly(LLA-ε-CL-AC)), a photo-cross-linkable and biodegradable polymer, for the first time. We show that the stiffness of the scaffolds increases significantly (up to ∼10-fold) after cross-linking by UV irradiation at room temperature, compared with un-cross-linked microfiber scaffolds. The preservation of stiffness and high average fiber modulus (370 ± 166 MPa) within the cross-linked hydrated scaffolds upon repetitive loading (10% strain at 1 Hz up to 200,000 cycles) suggests that the prepared scaffolds may be of potential interest for soft connective tissue engineering applications. Moreover, the approach can be readily adapted through manipulation of polymer properties and scaffold geometry to prepare structures with mechanical properties suitable for other tissue engineering applications. PMID:26620885

  18. Development and manufacture of printable next-generation gel polymer ionic liquid electrolyte for Zn/MnO2 batteries

    NASA Astrophysics Data System (ADS)

    Winslow, R.; Wu, C. H.; Wang, Z.; Kim, B.; Keif, M.; Evans, J.; Wright, P.

    2013-12-01

    While much energy storage research focuses on the performance of individual components, such as the electrolyte or a single electrode, few investigate the electrochemical system as a whole. This research reports on the design, composition, and performance of a Zn/MnO2 battery as affected by the manufacturing method and next-generation gel polymer electrolyte composed of the ionic liquid [BMIM][Otf], ZnOtf salt, and PVDF-HFP polymer binder. Materials and manufacturing tests are discussed with a focus on water concentration, surface features as produced by printing processes, and the effect of including a gel polymer phase. Cells produced for this research generated open circuit voltages from 1.0 to 1.3 V. A dry [BMIM][Otf] electrolyte was found to have 87.3 ppm of H2O, while an electrolyte produced in ambient conditions contained 12400 ppm of H2O. Cells produced in a dry, Ar environment had an average discharge capacity of 0.0137 mAh/cm2, while one produced in an ambient environment exhibited a discharge capacity at 0.05 mAh/cm2. Surface features varied significantly by printing method, where a doctor blade produced the most consistent features. The preliminary results herein suggest that water, surface roughness, and the gel polymer play important roles in affecting the performance of printed energy storage.

  19. Relaxation times in deformed polymer glasses: A comparison between molecular simulations and two theories

    NASA Astrophysics Data System (ADS)

    Rottler, Jörg

    2016-08-01

    Relaxation times in polymer glasses are computed with molecular dynamics simulations of a coarse-grained polymer model during creep and constant strain rate deformation. The dynamics is governed by a competition between physical aging that increases relaxation times and applied load or strain rate which accelerates dynamics. We compare the simulation results quantitatively to two recently developed theories of polymer deformation, which treat aging and rejuvenation in an additive manner. Through stress release and strain rate reversal simulations, we then show that the quantity governing mechanical rejuvenation is the rate of irreversible work performed on the polymer.

  20. Polymer Nanocomposites: Insights from Theory and Molecular Simulations

    NASA Astrophysics Data System (ADS)

    Pani, Rakhee

    Advantages of polymer nanocomposites have attracted great industrial attention due to their multifunctionality and innovative technological properties. Addition of small amount of nanoparticle (nanospheres, nanotubes, nanorods, nanoplatelets, or sheets) to polymer matrix cause dramatic improvement in structural and functional properties, which is difficult to attain from those of individual components. The interaction between polymer and nanoparticle create bulk materials dominated by solid state physics at the nanoscale. Furthermore, morphology of nanocomposites depends on structural arrangements of nanoparticles. Thus, for achievement of optimized functionality like electrical, optical, mechanical and thermal properties control over the dispersion of the nanoparticle is essential. However, properties of polymer nanocomposites depend on morphology control and nature of interfacial interactions. In order to control the morphology it is necessary to understand how the processing conditions, shape and size of nanoparticle influence the structure of composite. Molecular simulations can help us to predict the parameters that control the structural changes and we could design polymer nanocomposite entailing their end-use. In this work, we addressed the following research questions: (1) the dependence of nanoparticle ligand corona structure on solvent quality and (2) the role of interfacial energy and interactions on the dispersion of molecules and nanoparticles. Specifically, this research assessed the effect of solvent interactions on the structure of nanoparticles on the example of redox core encapsulating dendrimer and ligand functionalized gold nanoparticles, role of chemical interaction on solubility of glucose in ionic liquids, diffusion of fullerene nanoparticles in polymer matrix and influence of solubility parameters on the compatibility of gold nanoparticles with diblock copolymers. Computational methods allow quantifying the structure and flexibility of the

  1. Stretching of a polymer chain anchored to a surface: the massive field theory approach

    NASA Astrophysics Data System (ADS)

    Usatenko, Zoryana

    2014-09-01

    Taking into account the well-known correspondence between the field theoretical φ4 O(n)-vector model in the limit n → 0 and the behaviour of long-flexible polymer chains, the investigation of stretching of an ideal and a real polymer chain with excluded volume interactions in a good solvent anchored to repulsive and inert surfaces is performed. The calculations of the average stretching force which arises when the free end of a polymer chain moves away from a repulsive or inert surface are performed up to one-loop order of the massive field theory approach in fixed space dimensions d = 3. The analysis of the obtained results indicates that the average stretching force for a real polymer chain anchored to a repulsive surface demonstrates different behaviour for the cases \\tilde{z}\\ll1 and \\tilde{z}\\gg1 , where \\tilde{z}=z^\\prime/Rz . Besides, the results obtained in the framework of the massive field theory approach are in good agreement with previous theoretical results for an ideal polymer chain and results of a density functional theory approach for the region of small applied forces when deformation of a polymer chain in the direction of the applied force is not bigger than the linear extension of a polymer chain in this direction. The better agreement between these two methods is observed in the case where the number of monomers increases and the polymer chain becomes longer.

  2. Lattice density functional for colloid-polymer mixtures: comparison of two fundamental measure theories.

    PubMed

    Cuesta, José A; Lafuente, Luis; Schmidt, Matthias

    2005-09-01

    We consider a binary mixture of colloid and polymer particles with positions on a simple cubic lattice. Colloids exclude both colloids and polymers from nearest neighbor sites. Polymers are treated as effective particles that are mutually noninteracting, but exclude colloids from neighboring sites; this is a discrete version of the (continuum) Asakura-Oosawa-Vrij model. Two alternative density functionals are proposed and compared in detail. The first is based on multioccupancy in the zero-dimensional limit of the bare model, analogous to the corresponding continuum theory that reproduces the bulk fluid free energy of free volume theory. The second is based on mapping the polymers onto a multicomponent mixture of polymer clusters that are shown to behave as hard cores; the corresponding property of the extended model in strong confinement permits direct treatment with lattice fundamental measure theory. Both theories predict the same topology for the phase diagram with a continuous fluid-fcc freezing transition at low polymer fugacity and, upon crossing a tricritical point, a first-order freezing transition for high polymer fugacities with rapidly broadening density jump. PMID:16241433

  3. Validity of the scaling functional approach for polymer interfaces as a variational theory

    NASA Astrophysics Data System (ADS)

    Manghi, Manoel; Aubouy, Miguel

    2003-10-01

    We discuss the soundness of the scaling functional (SF) approach proposed by Aubouy Guiselin and Raphaël [Macromolecules 29, 7261 (1996)] to describe polymeric interfaces. In particular, we demonstrate that this approach is a variational theory. We emphasize the role of SF theory as an important link between ground-state theories suitable to describe adsorbed layers, and “classical” theories for polymer brushes.

  4. Nanoporous thin-film membranes from block-polymers : using self-consistent field theory calculations to guide polymer synthesis.

    SciTech Connect

    Cordaro, Joseph Gabriel

    2010-12-01

    The controlled self-assembly of polymer thin-films into ordered domains has attracted significant academic and industrial interest. Most work has focused on controlling domain size and morphology through modification of the polymer block-lengths, n, and the Flory-Huggins interaction parameter, {chi}. Models, such as Self-Consistent Field Theory (SCFT), have been successful in describing the experimentally observed morphology of phase-separated polymers. We have developed a computational method which uses SCFT calculations as a predictive tool in order to guide our polymer synthesis. Armed with this capability, we have the ability to select {chi} and then search for an ideal value of n such that a desired morphology is the most thermodynamically favorable. This approach enables us to synthesize new block-polymers with the exactly segment lengths that will undergo self-assembly to the desired morphology. As proof-of-principle we have used our model to predict the gyroidal domain for various block lengths using a fixed {chi} value. To validate our computational model, we have synthesized a series of block-copolymers in which only the total molecular length changes. All of these materials have a predicted thermodynamically favorable gyroidal morphology based on the results of our SCFT calculations. Thin-films of these polymers are cast and annealed in order to equilibrate the structure. Final characterization of the polymer thin-film morphology has been performed. The accuracy of our calculations compared to experimental results is discussed. Extension of this predictive ability to tri-block polymer systems and the implications to making functionalizable nanoporous membranes will be discussed.

  5. Rheology of cross-linked polymers and polymer foams: Theory and experimental results

    NASA Astrophysics Data System (ADS)

    Herman, John N.

    Typical polymers have a time-dependent response to loading which results in stress relaxation or creep. Models using springs/dashpots or Volterra integrals are capable of predicting the material response, but place little or no emphasis on the reasoning behind the response. This research proposes a microscopic reasoning behind polymer chain movement, while developing a model to predict the creep and stress relaxation of a polymer foam. Based on the theorized slip/stick of polymer chains as they slide past each other, this model successfully predicts the behavior of a PMI polymer foam under tensile loads. This model lends insights into polymer microscopic behavior, which may be used for the development of future polymer materials. When possible, industry standard test methods are used to obtain tensile creep and stress relaxation results from rectangular specimens of Rohacell 31 IG foam. A common set of material parameters is fitted to the data, validating the micromechanic reasoning to polymer chain movement. To gain insight into observed test result variability, an investigation of the elastic modulus and material density relationship is performed using nominal foam densities of 31 kg/m3, 51 kg/m3,, 71 kg/m3. Additional testing and modeling is performed to validate the model under load/partial-unload/ hold, load/unload/recovery, and load/instantaneous-unload test cycles. The model successfully captures the observed material nuances during these more complex loading cycles.

  6. A Fully Nonmetallic Gas Turbine Engine Enabled by Additive Manufacturing, Part II: Additive Manufacturing and Characterization of Polymer Composites

    NASA Technical Reports Server (NTRS)

    Chuang, Kathy C.; Grady, Joseph E.; Arnold, Steven M.; Draper, Robert D.; Shin, Eugene; Patterson, Clark; Santelle, Tom; Lao, Chao; Rhein, Morgan; Mehl, Jeremy

    2015-01-01

    This publication is the second part of the three part report of the project entitled "A Fully Nonmetallic Gas Turbine Engine Enabled by Additive Manufacturing" funded by NASA Aeronautics Research Institute (NARI). The objective of this project was to conduct additive manufacturing to produce aircraft engine components by Fused Deposition Modeling (FDM), using commercially available polyetherimides-Ultem 9085 and experimental Ultem 1000 mixed with 10% chopped carbon fiber. A property comparison between FDM-printed and injection molded coupons for Ultem 9085, Ultem 1000 resin and the fiber-filled composite Ultem 1000 was carried out. Furthermore, an acoustic liner was printed from Ultem 9085 simulating conventional honeycomb structured liners and tested in a wind tunnel. Composite compressor inlet guide vanes were also printed using fiber-filled Ultem 1000 filaments and tested in a cascade rig. The fiber-filled Ultem 1000 filaments and composite vanes were characterized by scanning electron microscope (SEM) and acid digestion to determine the porosity of FDM-printed articles which ranged from 25 to 31%. Coupons of Ultem 9085, experimental Ultem 1000 composites and XH6050 resin were tested at room temperature and 400F to evaluate their corresponding mechanical properties. A preliminary modeling was also initiated to predict the mechanical properties of FDM-printed Ultem 9085 coupons in relation to varied raster angles and void contents, using the GRC-developed MAC/GMC program.

  7. Communication: The simplified generalized entropy theory of glass-formation in polymer melts

    SciTech Connect

    Freed, Karl F.

    2015-08-07

    While a wide range of non-trivial predictions of the generalized entropy theory (GET) of glass-formation in polymer melts agree with a large number of observed universal and non-universal properties of these glass-formers and even for the dependence of these properties on monomer molecular structure, the huge mathematical complexity of the theory precludes its extension to describe, for instance, the perplexing, complex behavior observed for technologically important polymer films with thickness below ∼100 nm and for which a fundamental molecular theory is lacking for the structural relaxation. The present communication describes a hugely simplified version of the theory, called the simplified generalized entropy theory (SGET) that provides one component necessary for devising a theory for the structural relaxation of thin polymer films and thereby supplements the first required ingredient, the recently developed Flory-Huggins level theory for the thermodynamic properties of thin polymer films, before the concluding third step of combining all the components into the SGET for thin polymer films. Comparisons between the predictions of the SGET and the full GET for the four characteristic temperatures of glass-formation provide good agreement for a highly non-trivial model system of polymer melts with chains of the structure of poly(n-α olefins) systems where the GET has produced good agreement with experiment. The comparisons consider values of the relative backbone and side group stiffnesses such that the glass transition temperature decreases as the amount of excess free volume diminishes, contrary to general expectations but in accord with observations for poly(n-alkyl methacrylates). Moreover, the SGET is sufficiently concise to enable its discussion in a standard course on statistical mechanics or polymer physics.

  8. Communication: The simplified generalized entropy theory of glass-formation in polymer melts

    NASA Astrophysics Data System (ADS)

    Freed, Karl F.

    2015-08-01

    While a wide range of non-trivial predictions of the generalized entropy theory (GET) of glass-formation in polymer melts agree with a large number of observed universal and non-universal properties of these glass-formers and even for the dependence of these properties on monomer molecular structure, the huge mathematical complexity of the theory precludes its extension to describe, for instance, the perplexing, complex behavior observed for technologically important polymer films with thickness below ˜100 nm and for which a fundamental molecular theory is lacking for the structural relaxation. The present communication describes a hugely simplified version of the theory, called the simplified generalized entropy theory (SGET) that provides one component necessary for devising a theory for the structural relaxation of thin polymer films and thereby supplements the first required ingredient, the recently developed Flory-Huggins level theory for the thermodynamic properties of thin polymer films, before the concluding third step of combining all the components into the SGET for thin polymer films. Comparisons between the predictions of the SGET and the full GET for the four characteristic temperatures of glass-formation provide good agreement for a highly non-trivial model system of polymer melts with chains of the structure of poly(n-α olefins) systems where the GET has produced good agreement with experiment. The comparisons consider values of the relative backbone and side group stiffnesses such that the glass transition temperature decreases as the amount of excess free volume diminishes, contrary to general expectations but in accord with observations for poly(n-alkyl methacrylates). Moreover, the SGET is sufficiently concise to enable its discussion in a standard course on statistical mechanics or polymer physics.

  9. Self-consistent field theory of polymer-ionic molecule complexation.

    PubMed

    Nakamura, Issei; Shi, An-Chang

    2010-05-21

    A self-consistent field theory is developed for polymers that are capable of binding small ionic molecules (adsorbates). The polymer-ionic molecule association is described by Ising-like binding variables, C(i) ((a))(kDelta)(=0 or 1), whose average determines the number of adsorbed molecules, n(BI). Polymer gelation can occur through polymer-ionic molecule complexation in our model. For polymer-polymer cross-links through the ionic molecules, three types of solutions for n(BI) are obtained, depending on the equilibrium constant of single-ion binding. Spinodal lines calculated from the mean-field free energy exhibit closed-loop regions where the homogeneous phase becomes unstable. This phase instability is driven by the excluded-volume interaction due to the single occupancy of ion-binding sites on the polymers. Moreover, sol-gel transitions are examined using a critical degree of conversion. A gel phase is induced when the concentration of adsorbates is increased. At a higher concentration of the adsorbates, however, a re-entrance from a gel phase into a sol phase arises from the correlation between unoccupied and occupied ion-binding sites. The theory is applied to a model system, poly(vinyl alcohol) and borate ion in aqueous solution with sodium chloride. Good agreement between theory and experiment is obtained. PMID:20499947

  10. Origins of the Failure of Classical Nucleation Theory for Nanocellular Polymer Foams

    NASA Astrophysics Data System (ADS)

    Thompson, Russell; Kim, Yeongyoon

    2011-03-01

    The behavior of nanocellular polymer foams, in which nanometer-sized bubbles of fluid are dispersed in a polymer matrix, is dominated by its internal surfaces. In particular, nucleation of a nanocellular foam can involve fundamentally different physics from microcellular or regular foams due to properties of the surfaces. Nucleation rates for nano-bubbles in polymer have been calculated using both classical nucleation theory and self-consistent field theory. An identical model is used for both calculations showing that classical nucleation theory predictions are off by many orders of magnitude. The cause of the failure of classical nucleation theory can be traced primarily to its representation of a bubble surface as an infinite planar interface. For nanoscopic bubbles, the curvature of the bubble surface is comparable to the size of the polymer molecules. Polymers on the outside of a curved bubble surface can explore more conformations than can polymers next to a flat interface. This results in a lower free energy for the curved interface system with respect to a flat interface system, which gives a significantly smaller barrier energy to nucleation and thus a much higher nucleation rate. Funding: NSERC Strategic Projects Grant, NSERC Discovery Grant.

  11. Tomonaga-Luttinger liquid theory for metallic fullurene polymers

    NASA Astrophysics Data System (ADS)

    Yoshioka, Hideo; Shima, Hiroyuki; Noda, Yusuke; Ono, Shota; Ohno, Kaoru

    2016-04-01

    We investigate the low energy behavior of local density of states in metallic C60 polymers theoretically. The multichannel bosonization method is applied to electronic band structures evaluated from first-principles calculation, by which the effects of electronic correlation and nanoscale corrugation in the atomic configuration are fully taken into account. We obtain a closed-form expression for the power-law anomalies in the local density of states, which successfully describes the experimental observation on the C60 polymers in a quantitative manner. An important implication from the closed-form solution is the existence of an experimentally unobserved crossover at nearly a hundred milli-electron volts, beyond which the power-law exponent of the C60 polymers should change significantly.

  12. Analytical theory of polymer-network-mediated interaction between colloidal particles

    PubMed Central

    Di Michele, Lorenzo; Zaccone, Alessio; Eiser, Erika

    2012-01-01

    Nanostructured materials based on colloidal particles embedded in a polymer network are used in a variety of applications ranging from nanocomposite rubbers to organic-inorganic hybrid solar cells. Further, polymer-network-mediated colloidal interactions are highly relevant to biological studies whereby polymer hydrogels are commonly employed to probe the mechanical response of living cells, which can determine their biological function in physiological environments. The performance of nanomaterials crucially relies upon the spatial organization of the colloidal particles within the polymer network that depends, in turn, on the effective interactions between the particles in the medium. Existing models based on nonlocal equilibrium thermodynamics fail to clarify the nature of these interactions, precluding the way toward the rational design of polymer-composite materials. In this article, we present a predictive analytical theory of these interactions based on a coarse-grained model for polymer networks. We apply the theory to the case of colloids partially embedded in cross-linked polymer substrates and clarify the origin of attractive interactions recently observed experimentally. Monte Carlo simulation results that quantitatively confirm the theoretical predictions are also presented. PMID:22679289

  13. Doubly self-consistent field theory of grafted polymers under simple shear in steady state

    SciTech Connect

    Suo, Tongchuan; Whitmore, Mark D.

    2014-03-21

    We present a generalization of the numerical self-consistent mean-field theory of polymers to the case of grafted polymers under simple shear. The general theoretical framework is presented, and then applied to three different chain models: rods, Gaussian chains, and finitely extensible nonlinear elastic (FENE) chains. The approach is self-consistent at two levels. First, for any flow field, the polymer density profile and effective potential are calculated self-consistently in a manner similar to the usual self-consistent field theory of polymers, except that the calculation is inherently two-dimensional even for a laterally homogeneous system. Second, through the use of a modified Brinkman equation, the flow field and the polymer profile are made self-consistent with respect to each other. For all chain models, we find that reasonable levels of shear cause the chains to tilt, but it has very little effect on the overall thickness of the polymer layer, causing a small decrease for rods, and an increase of no more than a few percent for the Gaussian and FENE chains. Using the FENE model, we also probe the individual bond lengths, bond correlations, and bond angles along the chains, the effects of the shear on them, and the solvent and bonded stress profiles. We find that the approximations needed within the theory for the Brinkman equation affect the bonded stress, but none of the other quantities.

  14. A time dependent theory of crazing behavior in polymers

    NASA Technical Reports Server (NTRS)

    Chern, S. S.; Hsiao, C. C.

    1982-01-01

    The development of crazing is not only a function of stress, but also a function of time. Under a simple state of tension, a craze opening displacement is closely associated with the viscoelastic behavior of the original bulk polymer medium in which individual crazes initiate and develop. Within each craze region, molecular orientation takes place when conditions permit, and a new phase of rearranged molecules governs its local behavior. Based upon a time-dependent viscoelastic two-dimensional model, using a computer program the craze opening displacement field has been calculated, time-dependent craze length was also computed by taking into consideration the molecular orientation mechanism and large deformations in the craze region. Examples are given for simple viscoelastic media with simplified stress distributions. It is interesting to find out that the occurrence of crazing may be interpreted in terms of the stability or instability of the constitutive behavior of the bulk polymer.

  15. Time dependent mechanical modeling for polymers based on network theory

    NASA Astrophysics Data System (ADS)

    Billon, Noëlle

    2016-05-01

    Despite of a lot of attempts during recent years, complex mechanical behaviour of polymers remains incompletely modelled, making industrial design of structures under complex, cyclic and hard loadings not totally reliable. The non linear and dissipative viscoelastic, viscoplastic behaviour of those materials impose to take into account non linear and combined effects of mechanical and thermal phenomena. In this view, a visco-hyperelastic, viscoplastic model, based on network description of the material has recently been developed and designed in a complete thermodynamic frame in order to take into account those main thermo-mechanical couplings. Also, a way to account for coupled effects of strain-rate and temperature was suggested. First experimental validations conducted in the 1D limit on amorphous rubbery like PMMA in isothermal conditions led to pretty goods results. In this paper a more complete formalism is presented and validated in the case of a semi crystalline polymer, a PA66 and a PET (either amorphous or semi crystalline) are used. Protocol for identification of constitutive parameters is described. It is concluded that this new approach should be the route to accurately model thermo-mechanical behaviour of polymers using a reduced number of parameters of some physicl meaning.

  16. Recent advances with generalized entropy theory of glass-formation in polymers

    NASA Astrophysics Data System (ADS)

    Freed, Karl

    The generalized entropy theory (GET) of glass-formation in polymers is a combination of the lattice cluster theory (LCT) for the configurational entropy density with the Adam-Gibbs (AG) theory for the structural relaxation time. A greatly simplified form of the GET (whose expression for the free energy is roughly double that of Flory-Huggins theory) accurately reproduces the four characteristic temperatures of glass-formation (the onset, crossover, glass transition, and Kauzmann temperatures) of the full GET to within 4K for a series of models of polymers composed of semi-flexible chains having the structure of poly(n-alpha olefins). The theory is now simple enough to be used in courses in polymer physics. Although the successes of the GET provide a strong validation of the final form of the AG theory provided the configurational entropy is used, the physical basis of the AG theory has remained an enigma. Hence, we have developed a new, more general, statistical mechanical derivation of AG theory that explains the previously perplexing observations that the string-like elementary excitations have the mass and temperature dependence of systems undergoing equilibrium self-assembly. This work is supported by the (U.S.) Department of Energy (DOE), Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award No. DE- SC0008631.

  17. Statistical Mechanical Theory of Penetrant Diffusion in Polymer Melts and Glasses

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Schweizer, Kenneth

    We generalize our force-level, self-consistent nonlinear Langevin equation theory of activated diffusion of a dilute spherical penetrant in hard sphere fluids to predict the long-time diffusivity of molecular penetrants in supercooled polymer liquids and non-aging glasses. Chemical complexity is treated using an a priori mapping to a temperature-dependent hard sphere mixture model where polymers are disconnected into effective spheres based on the Kuhn length as the relevant coarse graining scale. A key parameter for mobility is the penetrant to polymer segment diameter ratio, R. Our calculations agree well with experimental measurements for a wide range of temperatures, penetrant sizes (from gas molecules with R ~0.3 to aromatic molecules with R ~1) and diverse amorphous polymers, over 10 decades variation of penetrant diffusivity. Structural parameter transferability is good. We have also formulated a theory at finite penetrant loading for the coupled penetrant-polymer dynamics in chemically (nearly) matched mixtures (e.g., toluene-polystyrene) which captures well the increase of penetrant diffusivity and decrease of polymer matrix vitrification temperature with increasing loading.

  18. Dynamic bottleneck elimination in mattress manufacturing line using theory of constraints.

    PubMed

    Gundogar, Emin; Sari, Murat; Kokcam, Abdullah H

    2016-01-01

    There is a tough competition in the furniture sector like other sectors. Along with the varying product range, production system should also be renewed on a regular basis and the production costs should be kept under control. In this study, spring mattress manufacturing line of a furniture manufacturing company is analyzed. The company wants to increase its production output with new investments. The objective is to find the bottlenecks in production line in order to balance the semi-finished material flow. These bottlenecks are investigated and several different scenarios are tested to improve the current manufacturing system. The problem with a main theme based on the elimination of the bottleneck is solved using Goldratt and Cox's theory of constraints with a simulation based heuristic method. Near optimal alternatives are determined by system models built in Arena 13.5 simulation software. Results show that approximately 46 % capacity enhancements with 2 buffer stocks have increased average production by 88.8 %. PMID:27547651

  19. Rate constitutive theories for ordered thermoviscoelastic fluids: polymers

    NASA Astrophysics Data System (ADS)

    Surana, K. S.; Nunez, D.; Reddy, J. N.; Romkes, A.

    2013-03-01

    This paper presents development of rate constitutive theories for compressible as well as in incompressible ordered thermoviscoelastic fluids, i.e., polymeric fluids in Eulerian description. The polymeric fluids in this paper are considered as ordered thermoviscoelastic fluids in which the stress rate of a desired order, i.e., the convected time derivative of a desired order `m' of the chosen deviatoric Cauchy stress tensor, and the heat vector are functions of density, temperature, temperature gradient, convected time derivatives of the chosen strain tensor up to any desired order `n' and the convected time derivative of up to orders `m-1' of the chosen deviatoric Cauchy stress tensor. The development of the constitutive theories is presented in contravariant and covariant bases, as well as using Jaumann rates. The polymeric fluids described by these constitutive theories will be referred to as ordered thermoviscoelastic fluids due to the fact that the constitutive theories are dependent on the orders `m' and `n' of the convected time derivatives of the deviatoric Cauchy stress and conjugate strain tensors. The highest orders of the convected time derivative of the deviatoric Cauchy stress and strain tensors define the orders of the polymeric fluid. The admissibility requirement necessitates that the constitutive theories for the stress tensor and heat vector satisfy conservation laws, hence, in addition to conservation of mass, balance of momenta, and conservation of energy, the second law of thermodynamics, i.e., Clausius-Duhem inequality must also be satisfied by the constitutive theories or be used in their derivations. If we decompose the total Cauchy stress tensor into equilibrium and deviatoric components, then Clausius-Duhem inequality and Helmholtz free-energy density can be used to determine the equilibrium stress in terms of thermodynamic pressure for compressible fluids and in terms of mechanical pressure for incompressible fluids, but the second law

  20. Rate constitutive theories for ordered thermoviscoelastic fluids: polymers

    NASA Astrophysics Data System (ADS)

    Surana, K. S.; Nunez, D.; Reddy, J. N.; Romkes, A.

    2014-03-01

    This paper presents development of rate constitutive theories for compressible as well as in incompressible ordered thermoviscoelastic fluids, i.e., polymeric fluids in Eulerian description. The polymeric fluids in this paper are considered as ordered thermoviscoelastic fluids in which the stress rate of a desired order, i.e., the convected time derivative of a desired order ` m' of the chosen deviatoric Cauchy stress tensor, and the heat vector are functions of density, temperature, temperature gradient, convected time derivatives of the chosen strain tensor up to any desired order ` n' and the convected time derivative of up to orders ` m-1' of the chosen deviatoric Cauchy stress tensor. The development of the constitutive theories is presented in contravariant and covariant bases, as well as using Jaumann rates. The polymeric fluids described by these constitutive theories will be referred to as ordered thermoviscoelastic fluids due to the fact that the constitutive theories are dependent on the orders ` m' and ` n' of the convected time derivatives of the deviatoric Cauchy stress and conjugate strain tensors. The highest orders of the convected time derivative of the deviatoric Cauchy stress and strain tensors define the orders of the polymeric fluid. The admissibility requirement necessitates that the constitutive theories for the stress tensor and heat vector satisfy conservation laws, hence, in addition to conservation of mass, balance of momenta, and conservation of energy, the second law of thermodynamics, i.e., Clausius-Duhem inequality must also be satisfied by the constitutive theories or be used in their derivations. If we decompose the total Cauchy stress tensor into equilibrium and deviatoric components, then Clausius-Duhem inequality and Helmholtz free-energy density can be used to determine the equilibrium stress in terms of thermodynamic pressure for compressible fluids and in terms of mechanical pressure for incompressible fluids, but the second

  1. Theory of chromatography of partially cyclic polymers: Tadpole-type and manacle-type macromolecules.

    PubMed

    Vakhrushev, Andrey V; Gorbunov, Alexei A

    2016-02-12

    A theory of chromatography is developed for partially cyclic polymers of tadpole- and manacle-shaped topological structures. We present exact equations for the distribution coefficient K at different adsorption interactions; simpler approximate formulae are also derived, relevant to the conditions of size-exclusion, adsorption, and critical chromatography. Theoretical chromatograms of heterogeneous partially cyclic polymers are simulated, and conditions for good separation by topology are predicted. According to the theory, an effective SEC-radius of tadpoles and manacles is mostly determined by the molar mass M, and by the linear-cyclic composition. In the interactive chromatography, the effect of molecular topology on the retention becomes significant. At the critical interaction point, partial dependences K(Mlin) and K(Mring) are qualitatively different: while being almost independent of Mlin, K increases with Mring. This behavior could be realized in critical chromatography-for separation of partially cyclic polymers by the number and molar mass of cyclic elements. PMID:26803439

  2. Macroscopic Surface Structures for Polymer-metal Hybrid Joints Manufactured by Laser Based Thermal Joining

    NASA Astrophysics Data System (ADS)

    Schricker, Klaus; Stambke, Martin; Bergmann, Jean Pierre; Bräutigam, Kevin; Henckell, Philipp

    The increasing application of hybrid structures in component design and fabrication allows to constantly enhance the realization of lightweight potentials. Laser-based joining of metals to polymers can obtaina local bonding with high load bearing capability. During the process, the polymer gets molten by the energy input of the laser beam and penetrates into the structure of the metal surface by means of a defined joining pressure. Macroscopic structures on the metal surface, produced by cutting or laser processing, are possible surface treatmentsfor achieving thepolymer-metal joints. The optimal geometry and other key parameters for the macroscopic surface structures are only partially known at present, e.g. a rising structure density causes a higher load capacity. Based on grooves and drilled holes, as referencegeometries, the depth (0.1-0.9 mm), width (0.3-1.1 mm), alignment angle, diameter (1.0mm- 1.5mm), structure density and penetration depth of the molten polymer were correlated to the separation force. The results allow an essential insight into the main effects ofmacroscopic structures on the mechanical joint properties and the material performance of the polymer during the process.

  3. Fluids density functional theory studies of supramolecular polymers at a hard surface

    NASA Astrophysics Data System (ADS)

    McGarrity, E. S.; Thijssen, J. M.; Besseling, N. A. M.

    2010-08-01

    We have applied a fluids density functional theory based on that of Yu and Wu [J. Chem. Phys. 116, 7094 (2002)] to treat reversible supramolecular polymers near a hard surface. This approach combines a hard-sphere fluids density functional theory with the first-order thermodynamic perturbation theory of Wertheim. The supramolecular polymers are represented in the theory by hard-spheres with two associating sites. We explore the effects of the bonding scheme, monomer concentration, and association energy upon the equilibrium chain sizes and the depletion lengths. This study is performed on simple systems containing two-site monomers and binary mixtures of two-site monomers combined with end stopper monomers which have only a single association site. Our model has correct behavior in the dilute and overlap regimes and the bulk results can be easily connected to simpler random-flight models. We find that there is a nonmonotonic behavior of the depletion length of the polymers as a function of concentration and that this depletion length can be controlled through the concentration of end stoppers. These results are applicable to the study of colloidal dispersions in supramolecular polymer solutions.

  4. Binary Mutual Diffusion Coefficients of Polymer/Solvent Systems Using Compressible Regular Solutions Theory and Free Volume Theory

    NASA Astrophysics Data System (ADS)

    Farajnezhad, Arsalan; Asef Afshar, Orang; Asgarpour Khansary, Milad; Shirazian, Saeed

    2016-07-01

    The free volume theory has found practical application for prediction of diffusional behavior of polymer/solvent systems. In this paper, reviewing free volume theory, binary mutual diffusion coefficients in some polymer/solvent systems have been systematically presented through chemical thermodynamic modeling in terms of both activity coefficients and fugacity coefficients models. Here chemical thermodynamic model of compressible regular solution (CRS) was used for evaluation of diffusion coefficients calculations as the pure component properties would be required only. Four binary polymeric solutions of cyclohexane/polyisobutylene, n-pentane/polyisobutylene, toluene/polyisobutylene and chloroform/polyisobutylene were considered. The agreement between calculated data and the experimentally collected data was desirable and no considerable error propagation in approximating mutual diffusion coefficients has been observed.

  5. Crystal structures and properties of nylon polymers from theory

    SciTech Connect

    Dasgupta, S.; Goddard, W.A. III; Hammond, W.B.

    1996-12-11

    A complete force field (MSXX) for simulation of all nylon polymers is derived from ab initio quantum calculations. Special emphasis is given to the accuracy of the hydrogen bond potential for the amide unit and the torsional potential between the peptide and alkane fragments. The MSXX force field was used to predict the structures, moduli, and detailed geometries of all nine nylons for which there are experimental crystal data plus one other. For nylon-(2n) with 2n = 6, the {alpha} crystal structure (with all-trans CH{sub 2} chains nearly coplanar with the hydrogen bonding plane) is more stable, while for 2n > 6, {gamma} (with the alkane plane twisted by 70{degree}) is more stable. This change results from the increased importance of methylene packing interactions over H bonds for larger 2n. We find the highest Young`s modulus for nylon-7. 51 refs., 6 figs., 7 tabs.

  6. Highly Aligned Carbon Fiber in Polymer Composite Structures via Additive Manufacturing

    DOE PAGESBeta

    Tekinalp, Halil L; Kunc, Vlastimil; Velez-Garcia, Gregorio M; Duty, Chad E; Love, Lonnie J; Naskar, Amit K; Blue, Craig A; Ozcan, Soydan

    2014-01-01

    Additive manufacturing, diverging from traditional manufacturing techniques, such as casting and machining materials, can handle complex shapes with great design flexibility without the typical waste. Although this technique has been mainly used for rapid prototyping, interest is growing in using this method to directly manufacture actual parts of complex shape. To use 3D-printing additive manufacturing in wide spread applications, the technique and the feedstock materials require improvements to meet the mechanical requirements of load-bearing components. Thus, we investigated the short fiber (0.2 mm to 0.4 mm) reinforced acrylonitrile-butadiene-styrene composites as a feedstock for 3D-printing in terms of their processibility, microstructuremore » and mechanical performance; and also provided comparison with traditional compression molded composites. The tensile strength and modulus of 3D-printed samples increased ~115% and ~700%, respectively. 3D-printer yielded samples with very high fiber orientation in printing direction (up to 91.5 %), whereas, compression molding process yielded samples with significantly less fiber orientation. Microstructure-mechanical property relationships revealed that although the relatively high porosity is observed in the 3D-printed composites as compared to those produced by the conventional compression molding technique, they both exhibited comparable tensile strength and modulus. This phenomena is explained based on the changes in fiber orientation, dispersion and void formation.« less

  7. Polymer blends for use in photoelectrochemical cells for conversion of solar energy to electricity and methods for manufacturing such blends

    DOEpatents

    Skotheim, Terje

    1984-01-01

    There is disclosed a polymer blend of a highly conductive polymer and a solid polymer electrolyte that is designed to achieve better charge transfer across the conductive film/polymer electrolyte interface of the electrochemical photovoltaic cell. The highly conductive polymer is preferably polypyrrole or poly-N-p-nitrophenylpyrrole and the solid polymer electrolyte is preferably polyethylene oxide or polypropylene oxide.

  8. Polymer blends for use in photoelectrochemical cells for conversion of solar energy to electricity and methods for manufacturing such blends

    DOEpatents

    Skotheim, T.

    A polymer blend is disclosed of a highly conductive polymer and a solid polymer electrolyte that is designed to achieve better charge transfer across the conductive film/polymer electrolyte interface of the electrochemical photovoltaic cell. The highly conductive polymer is preferably polypyrrole or poly-N-p-nitrophenylpyrrole and the solid polymer electrolyte is preferably polyethylene oxide or polypropylene oxide.

  9. Research in manufacturing of micro-structured injection molded polymer parts

    NASA Astrophysics Data System (ADS)

    Lucyshyn, Thomas; Struklec, Tobias; Burgsteiner, Martin; Graninger, Georg; Holzer, Clemens

    2015-12-01

    An overview of current research results is given for the topic of injection molding of micro-structured polymer parts regarding filling behavior and demolding process of micro-structures as well as the production of micro-structures on curved surfaces. In order to better understand how micro-structures are formed during the filling stage of injection molding, a study was performed on a test part with micro-channels placed parallely and perpendicularly to flow direction. Short shots with a highly fluent Polypropylene grade were injection molded with the melt front stopping in the structure fields. The melt and mold temperature, the injection rate as well as the use of a variotherm heating system were varied in a systematic Design of Experiments. The shape of the flow front was investigated with the optical measurement system Alicona InfiniteFocus. The data gained was analyzed with Matlab scripts and provided the needed distance to completely fill the structures as a reference value. The next topic covers the demolding step, which is a crucial process step in injection molding of micro-structured parts as the successfully replicated structures often get destroyed in the following demolding step. In order to evaluate the influence of the four aspects polymer, mold surface (coatings), structure (geometry and placement) and process settings on the demolding behavior, an injection mold with integrated measurement system was built, which makes it possible to measure the demolding force respectively a demolding energy under process conditions. These values can be used to quantitatively compare the impact of the above mentioned influencing factors on demolding. Finally, a concept to produce micro-structures on curved surfaces with injection molding is shown: A flat metal premaster structure is used to produce an elastomeric polymer (dimethylsiloxane) master in a casting process. This master is fixed in a conventional injection mold and a thermoplastic polymer is replicated

  10. Analytic models of regularly branched polymer brushes using the self-consistent mean field theory

    NASA Astrophysics Data System (ADS)

    LeSher, Daniel

    2015-10-01

    Polymer brushes consist of multiple monomers connected together with one of the polymer chain's ends attached to a surface. Polymer brushes have shown great promise for a wide variety of applications including drug delivery dendrimer systems and as tunable brushes that can change their shape and physical properties in response to changes in their environment. Regularly branched polymer brushes which are structured as a function of their chemical indices are investigated here using the self-consistent mean field theory for electrically neutral polymers. The brushes were described using weighting functions, f(n), were n was the fewest number of monomers from a specified location to a free end. Brushes with weighting functions of the form f(n)=nb, f(n)=ebn, as well as f(n)=dan when d 2 and alpha > 2 were found to match the parabolic free chain end profile expected, while it was determined that polymer brushes described using f(n)=n b must be very small in order to remain in equilibrium. However, brushes described by f(n)=2G(N-n) N and f(n)2n were found to be unstable for real, positive values of the potential of the system.

  11. Theory and Manufacturing Processes of Solar NanoAntenna Electromagnetic Collectors

    SciTech Connect

    Dale K. Kotter; Steven D. Novack

    2010-02-01

    DRAFT For Submittal to Journal of Solar Energy - Rev 10.1 ---SOL-08-1091 SOLAR Nantenna Electromagnetic Collectors Dale K. Kotter Idaho National Laboratory Steven D. Novack Idaho National Laboratory W. Dennis Slafer MicroContinuum, Inc. Patrick Pinhero University of Missouri ABSTRACT The research described in this paper explores a new and efficient approach for producing electricity from the abundant energy of the sun, using nanoantenna (nantenna) electromagnetic collectors (NECs). NEC devices target mid-infrared wavelengths, where conventional photovoltaic (PV) solar cells are inefficient and where there is an abundance of solar energy. The initial concept of designing NECs was based on scaling of radio frequency antenna theory to the infrared and visible regions. This approach initially proved unsuccessful because the optical behavior of materials in the terahertz (THz) region was overlooked and, in addition, economical nanofabrication methods were not previously available to produce the optical antenna elements. This paper demonstrates progress in addressing significant technological barriers, including: 1) development of frequency-dependent modeling of double-feedpoint square spiral nantenna elements; 2) selection of materials with proper THz properties; and 3) development of novel manufacturing methods that could potentially enable economical large-scale manufacturing. We have shown that nantennas can collect infrared energy and induce THz currents, and we have also developed cost-effective proof-of-concept fabrication techniques for the large-scale manufacture of simple square loop nantenna arrays. Future work is planned to embed rectifiers into the double-feedpoint antenna structures. This work represents an important first step toward the ultimate realization of a low-cost device that will collect as well as convert this radiation into electricity. This could lead to a broadband, high conversion efficiency low-cost solution to complement conventional PV

  12. Transition state theory approach to polymer escape from a one dimensional potential well

    NASA Astrophysics Data System (ADS)

    Mökkönen, Harri; Ikonen, Timo; Ala-Nissila, Tapio; Jónsson, Hannes

    2015-06-01

    The rate of escape of an ideal bead-spring polymer in a symmetric double-well potential is calculated using transition state theory (TST) and the results compared with direct dynamical simulations. The minimum energy path of the transitions becomes flat and the dynamics diffusive for long polymers making the Kramers-Langer estimate poor. However, TST with dynamical corrections based on short time trajectories started at the transition state gives rate constant estimates that agree within a factor of two with the molecular dynamics simulations over a wide range of bead coupling constants and polymer lengths. The computational effort required by the TST approach does not depend on the escape rate and is much smaller than that required by molecular dynamics simulations.

  13. An overview on the effect of manufacturing on the shock response of polymers

    NASA Astrophysics Data System (ADS)

    Kister, G.; Wood, D. C.; Appleby-Thomas, G. J.; Leighs, J. A.; Goff, M.; Barnes, N. R.; Hazell, P. J.

    2014-05-01

    Scatter and non-linearity of the Hugoniot in the Us-up plane has been seen in a number of polymers including poly(methyl methacrylate) (PMMA), the polymer considered here. In this study the plate impact technique has been used to investigate the shock response of PMMA between particle velocities of 0.13 and 0.77 mm μs-1. From this data no scatter was seen between our data and the experimental data of Barker and Hollenbach, and Carter and Marsh. Also a linear Hugoniot in the Us-up plane was found, with the equation Us = 2.99 + 0.92up. The non-linearity observed by Barker and Hollenbach was not present in this data, probably due to the non-linearity occur at particle velocities of below 0.13 mm μs-1, within their experimental data. Gruneisen gamma has also been briefly considered using a shock reverberation experiment but more work is needed before a value can be ascertained.

  14. An investigation of the structure-property relationships in ionic polymer polymer composites (IP2Cs) manufactured by polymerization in situ of PEDOT/PSS on Nafion®117

    NASA Astrophysics Data System (ADS)

    Di Pasquale, G.; Graziani, S.; Messina, F. G.; Pollicino, A.; Puglisi, R.; Umana, E.

    2014-03-01

    Ionic polymer polymer composites (IP2Cs) are all-organic electroactive polymers (EAPs) that show sensing and actuation capabilities when a deformation or a voltage is applied, respectively. They are fabricated starting from an ionic polymer coated on both sides with a conducting polymer as electrode element. In this work, poly(3,4-ethylendioxytiophene)-poly-(styrenesulfonate) (PEDOT/PSS) has been polymerized directly on Nafion®117 membrane and devices have been manufactured varying the polymerization time. Water and ethylene glycol (EG) have been used as solvents. The obtained IP2Cs have been characterized using thermal and mechanical analyses and electromechanically tested. The results have shown that in IP2Cs manufactured by polymerization in situ the PEDOT/PSS layer adheres very strongly on the Nafion®117 film, improving the possibility of rehydrating the devices after use. Moreover, taking into account that the different polymerization times influence the uniformity of the surface of the organic electrode and, consequently, both device stiffness and electrode conductivity, the structure-property relationships of the obtained devices have been investigated. The influence of the different solvents inside the devices has also been studied when IP2Cs have been used as actuators or sensors. Reported results show that it is possible to modulate the performances of IP2Cs by varying some manufacture parameters and the solvent.

  15. Architecture-Induced Size Asymmetry and Effective Interactions of Ring Polymers: Simulation and Theory

    PubMed Central

    2013-01-01

    We investigate, by means of Monte Carlo simulations, the role of ring architecture and topology on the relative sizes of two interacting polymers as a function of the distance between their centers-of-mass. As a general rule, polymers swell as they approach each other, irrespectively of their topologies. For each mutual separation, two identical linear polymers adopt the same average size. However, unknotted rings at close separations adopt different sizes, with the small one being “nested” within the large one over long time intervals, exchanging their roles in the course of the simulation. For two rings of different architectures and identical polymerization degree, the knotted one is always smaller, penetrating the unknotted one. On the basis of these observations, we propose a phenomenological theory for the effective interactions between rings, modeling them as unequal-sized penetrable spheres. This simple approximation provides a good description of the simulation results. In particular, it rationalizes the non-Gaussian shape and the short-distance plateau observed in the effective potential between unknotted ring polymers and pairs of unequal-sized unknotted/knotted ones. Our results demonstrate the crucial role of the architecture on both the effective interactions and the molecular size for strongly interpenetrating polymers. PMID:24347686

  16. Implementation of Laminate Theory Into Strain Rate Dependent Micromechanics Analysis of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.

    2000-01-01

    A research program is in progress to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to impact loads. Previously, strain rate dependent inelastic constitutive equations developed to model the polymer matrix were implemented into a mechanics of materials based micromechanics method. In the current work, the computation of the effective inelastic strain in the micromechanics model was modified to fully incorporate the Poisson effect. The micromechanics equations were also combined with classical laminate theory to enable the analysis of symmetric multilayered laminates subject to in-plane loading. A quasi-incremental trapezoidal integration method was implemented to integrate the constitutive equations within the laminate theory. Verification studies were conducted using an AS4/PEEK composite using a variety of laminate configurations and strain rates. The predicted results compared well with experimentally obtained values.

  17. Proposed sets of critical exponents for randomly branched polymers, using a known string theory model

    NASA Astrophysics Data System (ADS)

    March, N. H.; Moreno, A. J.

    2016-06-01

    The critical exponent ν for randomly branched polymers with dimensionality d equal to 3, is known exactly as 1/2. Here, we invoke an already available string theory model to predict the remaining static critical exponents. Utilizing results of Hsu et al. (Comput Phys Commun. 2005;169:114-116), results are added for d = 8. Experiment plus simulation would now be important to confirm, or if necessary to refine, the proposed values.

  18. Manufacturing technologies

    NASA Astrophysics Data System (ADS)

    The Manufacturing Technologies Center is at the core of Sandia National Laboratories' advanced manufacturing effort which spans the entire product realization process. The center's capabilities in product and process development are summarized in the following disciplines: (1) mechanical - rapid prototyping, manufacturing engineering, machining and computer-aided manufacturing, measurement and calibration, and mechanical and electronic manufacturing liaison; (2) electronics - advanced packaging for microelectronics, printed circuits, and electronic fabrication; and (3) materials - ceramics, glass, thin films, vacuum technology, brazing, polymers, adhesives, composite materials, and process analysis.

  19. Kinetic theory of a confined polymer driven by an external force and pressure-driven flow

    NASA Astrophysics Data System (ADS)

    Butler, Jason E.; Usta, O. Berk; Kekre, Rahul; Ladd, Anthony J. C.

    2007-11-01

    Kinetic theory is used to investigate the mechanisms causing cross-stream migration of confined polymers and polyelectrolytes under the influence of external forces and flow fields. Numerical simulations and experiments have demonstrated that confined polymers migrate towards the center of the channel in response to both external forces and uniaxial flows. Yet, migration towards the walls has been observed with combinations of external force and flow. In this paper, the kinetic theory for an elastic dumbbell developed by Ma and Graham [Phys. Fluids 17, 083103 (2005)] has been extended to account for the effects of an external force. Further modifications account for counterion screening within a Debye-Hückel approximation. This enables qualitative comparison with experimental results [Zheng and Yeung, Anal. Chem. 75, 3675 (2003)] on DNA migration under combined electric and pressure-driven flow fields. The comparison supports the contention [Long et al., Phys. Rev. Lett. 76, 3858 (1996)] that the hydrodynamic interactions in polyelectrolytes decay algebraically, as 1/r3, rather than exponentially. The theory qualitatively reproduces results of both simulations and experiments for the migration of neutral polymers and polyelectrolytes. Concentration profiles similar to those found in numerical simulations are observed, but the Peclet numbers differ by factors of 2-3.

  20. Kinetic theory for flows of nonhomogeneous rodlike liquid crystalline polymers with a nonlocal intermolecular potential.

    PubMed

    Wang, Qi; E, Weinan; Liu, Chun; Zhang, Pingwen

    2002-05-01

    The Doi kinetic theory for flows of homogeneous, rodlike liquid crystalline polymers (LCPs) is extended to model flows of nonhomogeneous, rodlike LCPs through a nonlocal (long-range) intermolecular potential. The theory features (i) a nonlocal, anisotropic, effective intermolecular potential in an integral form that is consistent with the chemical potential, (ii) short-range elasticity as well as long-range isotropic and anisotropic elasticity, (iii) a closed-form stress expression accounting for the nonlocal molecular interaction, and (iv) an extra elastic body force exclusively associated with the integral form of the intermolecular potential. With the effective intermolecular potential, the theory is proven to be well posed in that it warrants a positive entropy production and thereby the second law of thermodynamics. Approximate theories are obtained by gradient expansions of the number density function in the free energy density. PMID:12059561

  1. Fuzzy Set Theory Applied to Measurement Data for Exposure Control in Beryllium Part Manufacturing.

    SciTech Connect

    Parkinson, W. J. ,; Abeln, S. P.; Creek, K. L.; Mortensen, F. N.; Wantuck, P. J.; Ross, Timothy J.; Jamshidi, Mohammad

    2002-01-01

    Fuzzy set theory has been applied to some exposure control problems encountered in the machining and the manufacturing of beryllium parts at Los Alamos National Laboratory. A portion of that work is presented here. The major driving force for using fuzzy techniques in this case rather than classical statistical process control is that beryllium exposure is very task dependent and this manufacturing plant is quite atypical. It is feared that standard techniques produce too many false alarms. Our beryllium plant produces parts on a daily basis, but every day is different. Some days many parts are produced and some days only a few. Some times the parts are large and sometimes the parts are small. Some machining cuts are rough and some are fine. These factors and others make it hard to define a typical day. The problem of concern, for this study, is the worker beryllium exposure. Even though the plant is new and very modern and the exposure levels are expected to be well below the required levels, the Department of Energy (DOE), who is our major customer, has demanded that the levels for this plant be well below required levels. The control charts used to monitor this process are expected to answer two questions: (1) Is the process out of Control? Do we need to instigate special controls such as requiring workers to use respirators? (2) Are new, previously untested, controls making a difference? The standard Schewart type control charts, based on consistent plant operating conditions do not adequately answer this question. The approach described here is based upon a fuzzy modification to the Schewart Xbar-R chart. This approach is expected to yield better results than work based upon the classical probabilistic control chart.

  2. Valorisation of waste ilmenite mud in the manufacture of sulphur polymer cement.

    PubMed

    Contreras, Manuel; Gázquez, Manuel Jesús; García-Díaz, Irene; Alguacil, Francisco J; López, Félix A; Bolívar, Juan Pedro

    2013-10-15

    This paper reports the preparation of sulphur polymer cements (SPCs) incorporating waste ilmenite mud for use in concrete construction works. The ilmenite mud raw material and the mud-containing SPCs (IMC-SPCs) were characterised physico-chemically and radiologically. The optimal IMC-SPC mixture had a sulphur/mud ratio (w/w) of 1.05 (mud dose 20 wt%); this cement showed the greatest compressive strength (64 MPa) and the lowest water absorption coefficient (0.4 g cm(-2) at 28 days). Since ilmenite mud is enriched in natural radionuclides, such as radium isotopes (2.0·10(3) Bq kg(-1)(228)Ra and 5.0·10(2) Bq kg(-1)(226)Ra), the IMC-SPCs were subjected to leaching experiments, which showed their environmental impact to be negligible. The activity concentration indices for the different radionuclides in the IMC-SPCs containing 10% and 20% ilmenite mud met the demands of international standards for materials used in the construction of non-residential buildings. PMID:23845955

  3. Molecular theory of strain hardening of a polymer gel: Application to gelatin

    NASA Astrophysics Data System (ADS)

    Groot, Robert D.; Bot, Arjen; Agterof, Wim G. M.

    1996-06-01

    The elasticity of gelatin gels at large deformation has been measured for various experimental conditions. The general pattern is that stress increases with strain in a nonlinear way up to the point where the gel fails. To interpret this nonlinear stress increase, we studied a number of molecular models by Monte Carlo simulation and by mean-field methods. The effect of finite polymer length is studied via the FENE model (finite extensible nonlinear polymer connections) and via the exact statistics of Kramers' model (chains of freely rotating stiff rods) for a small number of elements per chain. To investigate the effect of fractal connections, the end-point distribution that comes forward from scaling theory has been generalized to arbitrary fractal dimension. Finally we studied a heterogeneous network model: connections formed by rods and coils. We also discuss the consequence of microphase separation. Combining experiment and theory we conclude the following: (i) The elastically active network connections in gelatin are most certainly not Gaussian. (ii) Strain hardening in gelatin can be attributed to either: (a) finite polymer length (the chain length between connection points should be some 2.5 times the persistence length), or (b) a fractal structure of the polymer strands (the fractal dimension should be roughly df=1.3-1.5), or (c) the presence of both stiff rods and flexible coils (the length of the rods should be 1.4-4.4 times the radius of gyration of the coils). (iii) Models b and c describe the experimental data significantly better than model a. From a single parameter (the fractal dimension) the fractal model correctly describes (1) the nonlinearity of the stress-strain curve, (2) the scaling of Young's modulus with polymer concentration, (3) the scaling of neutron scattering intensity with wave number, and (4) it predicts the scaling exponent of the linear dynamic modulus with frequency in the glassy transition zone (no experimental data available

  4. Nerve guides manufactured from photocurable polymers to aid peripheral nerve repair.

    PubMed

    Pateman, Christopher J; Harding, Adam J; Glen, Adam; Taylor, Caroline S; Christmas, Claire R; Robinson, Peter P; Rimmer, Steve; Boissonade, Fiona M; Claeyssens, Frederik; Haycock, John W

    2015-05-01

    The peripheral nervous system has a limited innate capacity for self-repair following injury, and surgical intervention is often required. For injuries greater than a few millimeters autografting is standard practice although it is associated with donor site morbidity and is limited in its availability. Because of this, nerve guidance conduits (NGCs) can be viewed as an advantageous alternative, but currently have limited efficacy for short and large injury gaps in comparison to autograft. Current commercially available NGC designs rely on existing regulatory approved materials and traditional production methods, limiting improvement of their design. The aim of this study was to establish a novel method for NGC manufacture using a custom built laser-based microstereolithography (μSL) setup that incorporated a 405 nm laser source to produce 3D constructs with ∼ 50 μm resolution from a photocurable poly(ethylene glycol) resin. These were evaluated by SEM, in vitro neuronal, Schwann and dorsal root ganglion culture and in vivo using a thy-1-YFP-H mouse common fibular nerve injury model. NGCs with dimensions of 1 mm internal diameter × 5 mm length with a wall thickness of 250 μm were fabricated and capable of supporting re-innervation across a 3 mm injury gap after 21 days, with results close to that of an autograft control. The study provides a technology platform for the rapid microfabrication of biocompatible materials, a novel method for in vivo evaluation, and a benchmark for future development in more advanced NGC designs, biodegradable and larger device sizes, and longer-term implantation studies. PMID:25725557

  5. Polymers.

    ERIC Educational Resources Information Center

    Tucker, David C.

    1986-01-01

    Presents an open-ended experiment which has students exploring polymer chemistry and reverse osmosis. This activity involves construction of a polymer membrane, use of it in a simple osmosis experiment, and application of its principles in solving a science-technology-society problem. (ML)

  6. Mortality of a cohort of workers in the styrene-butadiene polymer manufacturing industry (1943-1982)

    SciTech Connect

    Matanoski, G.M.; Santos-Burgoa, C.; Schwartz, L. )

    1990-06-01

    A cohort of 12,110 male workers employed 1 or more years in eight styrene-butadiene polymer (SBR) manufacturing plants in the United States and Canada has been followed for mortality over a 40-year period, 1943 to 1982. The all-cause mortality of these workers was low (standardized mortality ratio (SMR) = 0.81) compared to that of the general population. However, some specific sites of cancers had SMRs that exceeded 1.00. These sites were then examined by major work divisions. The sites of interest included leukemia and non-Hodgkin's lymphoma in whites. The SMRs for cancers of the digestive tract were higher than expected, especially esophageal cancer in whites and stomach cancer in blacks. The SMR for arteriosclerotic heart disease in black workers was significantly higher than would be expected based on general population rates. Employees were assigned to a work area based on job longest held. The SMRs for specific diseases differed by work area. Production workers showed increased SMRs for hematologic neoplasms and maintenance workers, for digestive cancers. A significant excess SMR for arteriosclerotic heart disease occurred only in black maintenance workers, although excess mortality from this disease occurred in blacks regardless of where they worked the longest. A significant excess SMR for rheumatic heart disease was associated with work in the combined, all-other work areas. For many causes of death, there were significant deficits in the SMRs.

  7. Mortality of a cohort of workers in the styrene-butadiene polymer manufacturing industry (1943-1982).

    PubMed Central

    Matanoski, G M; Santos-Burgoa, C; Schwartz, L

    1990-01-01

    A cohort of 12,110 male workers employed 1 or more years in eight styrene-butadiene polymer (SBR) manufacturing plants in the United States and Canada has been followed for mortality over a 40-year period, 1943 to 1982. The all-cause mortality of these workers was low [standardized mortality ratio (SMR) = 0.81] compared to that of the general population. However, some specific sites of cancers had SMRs that exceeded 1.00. These sites were then examined by major work divisions. The sites of interest included leukemia and non-Hodgkin's lymphoma in whites. The SMRs for cancers of the digestive tract were higher than expected, especially esophageal cancer in whites and stomach cancer in blacks. The SMR for arteriosclerotic heart disease in black workers was significantly higher than would be expected based on general population rates. Employees were assigned to a work area based on job longest held. The SMRs for specific diseases differed by work area. Production workers showed increased SMRs for hematologic neoplasms and maintenance workers, for digestive cancers. A significant excess SMR for arteriosclerotic heart disease occurred only in black maintenance workers, although excess mortality from this disease occurred in blacks regardless of where they worked the longest. A significant excess SMR for rheumatic heart disease was associated with work in the combined, all-other work areas. For many causes of death, there were significant deficits in the SMRs. PMID:2401250

  8. An alternative derivation of ring-polymer molecular dynamics transition-state theory

    NASA Astrophysics Data System (ADS)

    Hele, Timothy J. H.; Althorpe, Stuart C.

    2016-05-01

    In a previous article [T. J. H. Hele and S. C. Althorpe, J. Chem. Phys. 138, 084108 (2013)], we showed that the t → 0+ limit of ring-polymer molecular dynamics (RPMD) rate-theory is also the t → 0+ limit of a new type of quantum flux-side time-correlation function, in which the dividing surfaces are invariant to imaginary-time translation; in other words, that RPMD transition-state theory (RMPD-TST) is a t → 0+ quantum transition-state theory (QTST). Recently, Jang and Voth [J. Chem. Phys. 144, 084110 (2016)] rederived this quantum t → 0+ limit and claimed that it gives instead the centroid-density approximation. Here we show that the t → 0+ limit derived by Jang and Voth is in fact RPMD-TST.

  9. Fluid-fluid coexistence in an athermal colloid-polymer mixture: thermodynamic perturbation theory and continuum molecular-dynamics simulation

    NASA Astrophysics Data System (ADS)

    Jover, Julio; Galindo, Amparo; Jackson, George; Müller, Erich A.; Haslam, Andrew J.

    2015-09-01

    Using both theory and continuum simulation, we examine a system comprising a mixture of polymer chains formed from 100 hard-sphere (HS) segments and HS colloids with a diameter which is 20 times that of the polymer segments. According to Wertheim's first-order thermodynamic perturbation theory (TPT1) this athermal system is expected to phase separate into a colloid-rich and a polymer-rich phase. Using a previously developed continuous pseudo-HS potential [J. F. Jover, A. J. Haslam, A. Galindo, G. Jackson, and E. A. Muller, J. Chem. Phys. 137, 144505 (2012)], we simulate the system at a phase point indicated by the theory to be well within the two-phase binodal region. Molecular-dynamics simulations are performed from starting configurations corresponding to completely phase-separated and completely pre-mixed colloids and polymers. Clear evidence is seen of the stabilisation of two coexisting fluid phases in both cases. An analysis of the interfacial tension of the phase-separated regions is made; ultra-low tensions are observed in line with previous values determined with square-gradient theory and experiment for colloid-polymer systems. Further simulations are carried out to examine the nature of these coexisting phases, taking as input the densities and compositions calculated using TPT1 (and corresponding to the peaks in the probability distribution of the density profiles obtained in the simulations). The polymer chains are seen to be fully penetrable by other polymers. By contrast, from the point of view of the colloids, the polymers behave (on average) as almost-impenetrable spheres. It is demonstrated that, while the average interaction between the polymer molecules in the polymer-rich phase is (as expected) soft-repulsive in nature, the corresponding interaction in the colloid-rich phase is of an entirely different form, characterised by a region of effective intermolecular attraction.

  10. Examining the aggregation behavior of polymer grafted nanoparticles using molecular simulation and theory

    NASA Astrophysics Data System (ADS)

    Haley, Jessica D.; Iacovella, Christopher R.; Cummings, Peter T.; McCabe, Clare

    2015-08-01

    Grafting polymers to nanoparticles is one approach used to control and enhance the structure and properties of nanomaterials. However, predicting the aggregation behavior of tethered nanoparticles (TNPs) is a somewhat trial and error process as a result of the large number of possible polymer tethers, nanoparticles, and solvent species that can be studied. With the main goal of understanding how to control the dispersion and aggregation of TNP systems, molecular simulations and the hetero-statistical associating fluid theory for potentials of variable range have been used to calculate the fluid phase equilibrium of TNPs in both vacuum and in simple solvents under a wide range of conditions. The role of graft length, graft density, and solvent interactions is examined and trends established. Additionally, the fluid distribution ratio (k value) is used to study the solubility of TNPs in industrially relevant solvents including carbon dioxide, nitrogen, propane, and ethylene.

  11. Theory of Transport of Long Polymer Molecules through Carbon Nanotube Channels

    NASA Technical Reports Server (NTRS)

    Wei, Chenyu; Srivastava, Deepak

    2003-01-01

    A theory of transport of long chain polymer molecules through carbon nanotube (CNT) channels is developed using Fokker-Planck equation and direct molecular dynamics (MD) simulations. The mean transport or translocation time tau is found to depend on the chemical potential energy, entropy and diffusion coefficient. A power law dependence tau approx. N(sup 2)is found where N is number of monomers in a molecule. For 10(exp 5)-unit long polyethylene molecules, tau is estimated to be approx. 1micro-s. The diffusion coefficient of long polymer molecules inside CNTs, like that of short ones, are found to be few orders of magnitude larger than in ordinary silicate based zeolite systems.

  12. Shock compression of glow discharge polymer (GDP): density functional theory (DFT) simulations and experiments on Sandia's Z-machine

    NASA Astrophysics Data System (ADS)

    Cochrane, K. R.; Ao, T.; Hamel, S.; Lemke, R. W.; Schoff, M. E.; Blue, B. E.; Herrmann, M. C.; Mattsson, T. R.

    2015-06-01

    Glow discharge polymer (GDP) is used extensively in inertial confinement fusion (ICF) capsules. Accurate knowledge of the equation of state (EOS) under shock and release is particularly important for high-fidelity design and analysis of ICF experiments since the capsule material is subject to several converging shocks as well as release towards the cryogenic fuel. We performed Density Functional Theory (DFT) based molecular dynamics simulations, to gain knowledge of the behavior of GDP - for example regarding the role of chemical dissociation during shock compression, we find that the dissociation regime along the Hugoniot extends from 50 GPa to 250 GPa. The shock pressures calculated from DFT are compared to experimental data taken on magnetically launched flyer plate impact experiments at Sandia's Z-machine. Large GDP samples were grown in a planar geometry to improve the sample quality and maintained in a nitrogen atmosphere following manufacturing, thus allowing for a direct comparison to the simulations. Sandia National Laboratories is a multi program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's NNSA under Contract DE-AC04-94AL85000

  13. Shock compression of glow discharge polymer (GDP): density functional theory (DFT) simulations and experiments on Sandia's Z-machine

    NASA Astrophysics Data System (ADS)

    Mattsson, Thomas R.; Cochrane, K. R.; Ao, T.; Lemke, R. W.; Flicker, D. G.; Schoff, M. E.; Blue, B. E.; Hamel, S.; Herrmann, M. C.

    2015-11-01

    Glow discharge polymer (GDP) is used extensively as capsule/ablation material in inertial confinement fusion (ICF) capsules. Accurate knowledge of the equation of state (EOS) under shock and release is particularly important for high-fidelity design, analysis, and optimization of ICF experiments since the capsule material is subject to several converging shocks as well as release towards the cryogenic fuel. We performed Density Functional Theory (DFT) based quantum molecular dynamics (QMD) simulations, to gain knowledge of the behavior of GDP - including the effect of changes in chemical composition. The shock pressures calculated from DFT are compared experimental data taken on magnetically launched flyer plate impact experiments on at Sandia's Z-machine. Large GDP samples were grown in a planar geometry to improve the sample quality and maintained in a nitrogen atmosphere following manufacturing, thus allowing for a direct comparison to the DFT/QMD simulations. Sandia National Laboratories is a multi program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's NNSA under contract DE-AC04-94AL85000.

  14. A multi-species exchange model for fully fluctuating polymer field theory simulations

    SciTech Connect

    Düchs, Dominik; Delaney, Kris T.; Fredrickson, Glenn H.

    2014-11-07

    Field-theoretic models have been used extensively to study the phase behavior of inhomogeneous polymer melts and solutions, both in self-consistent mean-field calculations and in numerical simulations of the full theory capturing composition fluctuations. The models commonly used can be grouped into two categories, namely, species models and exchange models. Species models involve integrations of functionals that explicitly depend on fields originating both from species density operators and their conjugate chemical potential fields. In contrast, exchange models retain only linear combinations of the chemical potential fields. In the two-component case, development of exchange models has been instrumental in enabling stable complex Langevin (CL) simulations of the full complex-valued theory. No comparable stable CL approach has yet been established for field theories of the species type. Here, we introduce an extension of the exchange model to an arbitrary number of components, namely, the multi-species exchange (MSE) model, which greatly expands the classes of soft material systems that can be accessed by the complex Langevin simulation technique. We demonstrate the stability and accuracy of the MSE-CL sampling approach using numerical simulations of triblock and tetrablock terpolymer melts, and tetrablock quaterpolymer melts. This method should enable studies of a wide range of fluctuation phenomena in multiblock/multi-species polymer blends and composites.

  15. Incorporating the effect of orientation hardening in an effective temperature nonequilibrium theory for glassy polymers

    NASA Astrophysics Data System (ADS)

    Guo, Jingkai; Xiao, Rui; Nguyen, Thao

    Amorphous polymers exhibit a wide range of time and temperature dependent behavior. Recently, Xiao and Nguyen developed an effective temperature theory that can capture a wide variety of nonequilibrium behaviors at moderate strains. At large strains, the stress response of glassy polymers is dominated by strain hardening as a result of chain alignment. The goal of this study was to extend the effective temperature theory to large deformation and make it capable of modeling strain hardening from deformation-induced molecular alignment. We compared two approaches. In the spirit of internal state variable thermodynamics theory, we introduced a series of stretch-like internal state variables to characterize the molecular resistance to plastic flow associated with each inelastic mechanism. The dependence of free energy on the internal state variables naturally gives rise to a deformation dependent back stress. The flow rule and the evolution of effective temperatures were derived in a thermodynamically consistent manner. In the second approach, we introduced a steady-state limit in the evolution of the effective temperature characterizing the nonequilibrium structure of the material. Both approaches can well capture the experimentally measured phenomena of orientation hardening, including the development of deformation-induced anisotropy in the yield strength and hardening modulus, the Bauschinger effect, and differences in the hardening moduli in tension and compression of pre-oriented specimens.

  16. Application of graph theory to the statistical thermodynamics of lattice polymers. I. Elements of theory and test for dimers

    NASA Astrophysics Data System (ADS)

    Brazhnik, Olga D.; Freed, Karl F.

    1996-07-01

    The lattice cluster theory (LCT) is extended to enable inclusion of longer range correlation contributions to the partition function of lattice model polymers in the athermal limit. A diagrammatic technique represents the expansion of the partition function in powers of the inverse lattice coordination number. Graph theory is applied to sort, classify, and evaluate the numerous diagrams appearing in higher orders. New general theorems are proven that provide a significant reduction in the computational labor required to evaluate the contributions from higher order correlations. The new algorithm efficiently generates the correction to the Flory mean field approximation from as many as eight sterically interacting bonds. While the new results contain the essential ingredients for treating a system of flexible chains with arbitrary lengths and concentrations, the complexity of our new algorithm motivates us to test the theory here for the simplest case of a system of lattice dimers by comparison to the dimer packing entropies from the work of Gaunt. This comparison demonstrates that the eight bond LCT is exact through order φ5 for dimers in one through three dimensions, where φ is the volume fraction of dimers. A subsequent work will use the contracted diagrams, derived and tested here, to treat the packing entropy for a system of flexible N-mers at a volume fraction of φ on hypercubic lattices.

  17. Strong-coupling electrostatic theory of polymer counterions close to planar charges

    NASA Astrophysics Data System (ADS)

    Dutta, Sandipan; Jho, Y. S.

    2016-01-01

    Strong-coupling phenomena, such as like-charge macroion attraction, opposite-charged macroion repulsion, charge renormalization, and charge inversion, are known to be mediated by multivalent counterions. Most theories treat the counterions as point charges and describe the system by a single coupling parameter that measures the strength of the Coulomb interactions. In many biological systems, the counterions are highly charged and have finite sizes and can be well-described by polyelectrolytes. The shapes and orientations of these polymer counterions play a major role in the thermodynamics of these systems. In this work we apply a field-theoretic description in the strong-coupling regime to the polymer counterions in the presence of a fixed charge distribution. We work out the special cases of rodlike polymer counterions confined by one, and two charged walls, respectively. The effects of the geometry of the rodlike counterions and the excluded volume of the walls on the density, pressure, and free energy of the rodlike counterions are discussed.

  18. Rotational isomeric state theory applied to the stiffness prediction of an anion polymer electrolyte membrane

    SciTech Connect

    Gao, Fei; Weiland, L.M.; Kitchin, J.R.

    2008-05-01

    While the acidic polymer electrolyte membrane (PEM) Nafion® has garnered considerable attention, the active response of basic PEMs offers another realm of potential applications. For instance, the basic PEM Selemion® is currently being considered in the development of a CO2 separation prototype device to be employed in coal power plant flue gas. The mechanical integrity of this material and subsequent effects in active response in this harsh environment will become important in prototype development. A multiscale modeling approach based on rotational isomeric state theory in combination with a Monte Carlo methodology may be employed to study mechanical integrity. The approach has the potential to be adapted to address property change of any PEM in the presence of foreign species (reinforcing or poisoning), as well as temperature and hydration variations. The conformational characteristics of the Selemion® polymer chain and the cluster morphology in the polymer matrix are considered in the prediction of the stiffness of Selemion® in specific states.

  19. Contact line of adsorbed colloid-polymer droplets in theory and experiment.

    PubMed

    Koning, Jesper; Hennequin, Yves; Bonn, Daniel; Indekeu, Joseph O

    2016-05-01

    The contact line between the colloid-rich bulk liquid and an adsorbed thin film in colloid-polymer mixtures (CPM) is studied by means of an interface displacement model. The interface displacement profiles are compared to laser scanning confocal microscopy (LSCM) images. The mixtures consist of poly(methylmetacrylate) (PMMA) colloids and polystyrene (PS) polymers with polymer-to-colloid size ratio q = 1.18. Based on the experimental parameters, the theoretical model predicts a contact angle for colloid-rich liquid droplets adsorbed on glass of θ∞ = 59°, assuming a contact line with infinite radius, R = ∞. When a contact-line curvature correction and a correction for the protein-limit character of the CPM are taken into account, a modest shift is obtained. The refined theory predicts θ≈ 56°. The contact angle determined visually from the LSCM images is θ≈ 30°. The model predicts a three-phase contact-line tension of τ = -1.2 × 10(-12) N (uncorrected) and τ = -2.3 × 10(-13) N (with protein-limit correction), which is physically sound both in sign and magnitude. The line tension influences the contact angle to a small extent due to the contact line curvature. The predicted width of the transition zone between the thin film and the droplet is about 2 μm. The effect of gravity is noticeable as a deformation near the middle of the droplet. PMID:27029605

  20. A polymer microgel at a liquid-liquid interface: theory vs. computer simulations.

    PubMed

    Rumyantsev, Artem M; Gumerov, Rustam A; Potemkin, Igor I

    2016-08-10

    We propose a mean-field theory and dissipative particle dynamics (DPD) simulations of swelling and collapse of a polymer microgel adsorbed at the interface of two immiscible liquids (A and B). The microgel reveals surface activity and lowers A-B interfacial tension. Attempting to occupy as large an interfacial area as possible, the microgel undergoes anisotropic deformation and adopts a flattened shape. Spreading over the interface is restricted by polymer subchain elasticity. The equilibrium shape of the microgel at the interface depends on its size. Small microgels are shown to be more oblate than the larger microgels. Increasing microgel cross-link density results in stronger reduction of the surface tension and weaker flattening. As the degree of immiscibility of A and B liquids increases, the microgel volume changes in a non-monotonous fashion: the microgel contraction at moderate immiscibility of A and B liquids is followed by its swelling at high incompatibility of the liquids. The segregation regime of the liquids within and outside the microgel is different. Being segregated outside the microgel, the liquids can be fully (homogeneously) mixed or weakly segregated within it. The density profiles of the liquids and the polymer were plotted under different conditions. The theoretical and the DPD simulation results are in good agreement. We hope that our findings will be useful for the design of stimuli responsive emulsions, which are stabilized by the microgel particles, as well as for their practical applications, for instance, in biocatalysis. PMID:27460037

  1. Optimized cluster theory of polymer blends: General formulation and application to isotopic polyethylene mixtures

    NASA Astrophysics Data System (ADS)

    Melenkevitz, J.; Curro, J. G.

    1997-01-01

    A theory for the thermodynamic properties of binary polymer blends was developed and applied to predict the compositional dependence of the effective chi parameter χS in model isotopic polyethylene mixtures. The theory is a generalization of the optimized cluster theory for single component molecular fluids. Starting from exact cluster expansions for the Helmholtz free energy and pair-correlation functions in a molecular mixture developed by Chandler et al., a series of transformations was performed to yield approximate expressions for these quantities. The resulting theory was demonstrated to be equivalent to a set of diagrammatically proper integral equations. For model isotopic polyethylene blends, we calculated the various partial structure factors in the mixture and used them to predict the compositional dependence of χS. The calculated values of χS were found to be in reasonable agreement with recent neutron-scattering measurements but the theory underestimates the compositional dependence relative to the experiment. Deviations from random mixing that extend well beyond monomeric length scales were predicted in this blend system.

  2. A theory for species migration in a finitely strained solid with application to polymer network swelling

    NASA Astrophysics Data System (ADS)

    Duda, Fernando P.; Souza, Angela C.; Fried, Eliot

    2010-04-01

    We present a theory for the behavior of a solid undergoing two interdependent processes, a macroscopic or mechanical process due to the deformation of the solid and a microscopic or chemical process due to the migration of a chemical species through the solid. The principle of virtual power is invoked to deduce the basic balances of the theory, namely the mechanical force balance and the transport balance for the chemical species. In combination with thermodynamically consistent constitutive relations, these balances generate the basic equations of the theory. Keeping in mind applications involving the swelling of polymer networks by liquids, a specialization of the theory is presented and applied to study the influences of mechanical and chemical interactions on equilibrium states and diffusive dynamical processes. It is shown that the possibility of a mechanically induced phase transition is governed by two parameters: the Flory interaction parameter and a parameter given by the product between the number of cross-linked units per unit reference volume and the molecular volume of the liquid molecule. As for diffusion, it is shown that the theory is able to describe the pressure-induced diffusion in swollen membranes.

  3. Lattice model of linear telechelic polymer melts. I. Inclusion of chain semiflexibility in the lattice cluster theory

    NASA Astrophysics Data System (ADS)

    Xu, Wen-Sheng; Freed, Karl F.

    2015-07-01

    The lattice cluster theory (LCT) for the thermodynamics of polymer systems has recently been reformulated to treat strongly interacting self-assembling polymers composed of fully flexible linear telechelic chains [J. Dudowicz and K. F. Freed, J. Chem. Phys. 136, 064902 (2012)]. Here, we further extend the LCT for linear telechelic polymer melts to include a description of chain semiflexibility, which is treated by introducing a bending energy penalty whenever a pair of consecutive bonds from a single chain lies along orthogonal directions. An analytical expression for the Helmholtz free energy is derived for the model of semiflexible linear telechelic polymer melts. The extension provides a theoretical tool for investigating the influence of chain stiffness on the thermodynamics of self-assembling telechelic polymers, and for further exploring the influence of self-assembly on glass formation in such systems.

  4. Lattice model of linear telechelic polymer melts. I. Inclusion of chain semiflexibility in the lattice cluster theory.

    PubMed

    Xu, Wen-Sheng; Freed, Karl F

    2015-07-14

    The lattice cluster theory (LCT) for the thermodynamics of polymer systems has recently been reformulated to treat strongly interacting self-assembling polymers composed of fully flexible linear telechelic chains [J. Dudowicz and K. F. Freed, J. Chem. Phys. 136, 064902 (2012)]. Here, we further extend the LCT for linear telechelic polymer melts to include a description of chain semiflexibility, which is treated by introducing a bending energy penalty whenever a pair of consecutive bonds from a single chain lies along orthogonal directions. An analytical expression for the Helmholtz free energy is derived for the model of semiflexible linear telechelic polymer melts. The extension provides a theoretical tool for investigating the influence of chain stiffness on the thermodynamics of self-assembling telechelic polymers, and for further exploring the influence of self-assembly on glass formation in such systems. PMID:26178121

  5. Two- and three-dimensional nonlocal density functional theory for inhomogeneous fluids. 2. Solvated polymers as a benchmark problem

    SciTech Connect

    Frink, L.J.D.; Salinger, A.G.

    2000-04-10

    In a previous companion paper, the authors presented the details of the algorithms for performing nonlocal density functional theory calculations in complex two- and three-dimensional geometries. The authors discussed scaling and parallelization, but did not discuss other issues of performance. In this paper, they detail the precision of the methods with respect to changes in the mesh spacing. This is a complex issue because given a Cartesian mesh, changes in mesh spacing will result in changes in surface geometry. The authors discuss these issues using a series of rigid solvated polymer models including square rod polymers, cylindrical polymers, and bead-chain polymers. In comparing the results of the various models, it becomes clear that surface curvature or roughness plays an important role in determining the strength of structural solvation forces between interacting solvated polymers. The results in this paper serve as benchmarks for future applications of these algorithms to complex fluid systems.

  6. Lattice model of linear telechelic polymer melts. I. Inclusion of chain semiflexibility in the lattice cluster theory

    SciTech Connect

    Xu, Wen-Sheng; Freed, Karl F.

    2015-07-14

    The lattice cluster theory (LCT) for the thermodynamics of polymer systems has recently been reformulated to treat strongly interacting self-assembling polymers composed of fully flexible linear telechelic chains [J. Dudowicz and K. F. Freed, J. Chem. Phys. 136, 064902 (2012)]. Here, we further extend the LCT for linear telechelic polymer melts to include a description of chain semiflexibility, which is treated by introducing a bending energy penalty whenever a pair of consecutive bonds from a single chain lies along orthogonal directions. An analytical expression for the Helmholtz free energy is derived for the model of semiflexible linear telechelic polymer melts. The extension provides a theoretical tool for investigating the influence of chain stiffness on the thermodynamics of self-assembling telechelic polymers, and for further exploring the influence of self-assembly on glass formation in such systems.

  7. Theory of Aging, Rejuvenation, and the Nonequilibrium Steady State in Deformed Polymer Glasses

    SciTech Connect

    Chen, Kang

    2010-01-01

    The nonlinear Langevin equation theory of segmental relaxation, elasticity, and mechanical response of polymer glasses is extended to describe the coupled effects of physical aging, mechanical rejuvenation, and thermal history. The key structural variable is the amplitude of density fluctuations, and segmental dynamics proceeds via stress-modified activated barrier hopping on a dynamic free-energy profile. Mechanically generated disorder rejuvenation is quantified by a dissipative work argument and increases the amplitude of density fluctuations, thereby speeding up relaxation beyond that induced by the landscape tilting mechanism. The theory makes testable predictions for the time evolution and nonequilibrium steady state of the alpha relaxation time, density fluctuation amplitude, elastic modulus, and other properties. Model calculations reveal a rich dependence of these quantities on preaging time, applied stress, and temperature that reflects the highly nonlinear competition between physical aging and mechanical disordering. Thermal history is erased in the long-time limit, although the nonequilibrium steady state is not the literal fully rejuvenated freshly quenched glass. The present work provides the conceptual foundation for a quantitative treatment of the nonlinear mechanical response of polymer glasses under a variety of deformation protocols.

  8. Theory of polymer translocation through a flickering nanopore under an alternating driving force

    NASA Astrophysics Data System (ADS)

    Sarabadani, Jalal; Ikonen, Timo; Ala-Nissila, Tapio

    2015-08-01

    We develop a theory for polymer translocation driven by a time-dependent force through an oscillating nanopore. To this end, we extend the iso-flux tension propagation theory [Sarabadani et al., J. Chem. Phys. 141, 214907 (2014)] for such a setup. We assume that the external driving force in the pore has a component oscillating in time, and the flickering pore is similarly described by an oscillating term in the pore friction. In addition to numerically solving the model, we derive analytical approximations that are in good agreement with the numerical simulations. Our results show that by controlling either the force or pore oscillations, the translocation process can be either sped up or slowed down depending on the frequency of the oscillations and the characteristic time scale of the process. We also show that while in the low and high frequency limits, the translocation time τ follows the established scaling relation with respect to chain length N0, in the intermediate frequency regime small periodic, fluctuations can have drastic effects on the dynamical scaling. The results can be easily generalized for non-periodic oscillations and elucidate the role of time dependent forces and pore oscillations in driven polymer translocation.

  9. Excluded volume effects in compressed polymer brushes: A density functional theory

    SciTech Connect

    Chen, Cangyi; Tang, Ping E-mail: fengqiu@fudan.edu.cn; Qiu, Feng E-mail: fengqiu@fudan.edu.cn; Shi, An-Chang

    2015-03-28

    A classical density functional theory (DFT) is applied to investigate the behavior of compressed polymer brushes composed of hard-sphere chains. The excluded volume interactions among the chain segments are explicitly treated. Two compression systems are used to study the behavior of brush-wall and brush-brush interactions. For the brush-brush systems, an obvious interpenetration zone has been observed. The extent of the interpenetration depends strongly on the grafting density. Furthermore, the repulsive force between the brush and wall or between the two brushes has been obtained as a function of the compression distance. Compared to the prediction of the analytic self-consistent field theory, such force increases more rapidly in the brush-wall compression with high polymer grafting densities or at higher compressions. In the brush-brush compression system, the interpenetration between the two compressed brushes creates a “softer” interaction. The influence of hard-sphere solvents on the behavior of compressed brushes is also discussed.

  10. Thermodynamic scaling of dynamics in polymer melts: predictions from the generalized entropy theory.

    PubMed

    Xu, Wen-Sheng; Freed, Karl F

    2013-06-21

    Many glass-forming fluids exhibit a remarkable thermodynamic scaling in which dynamic properties, such as the viscosity, the relaxation time, and the diffusion constant, can be described under different thermodynamic conditions in terms of a unique scaling function of the ratio ρ(γ)∕T, where ρ is the density, T is the temperature, and γ is a material dependent constant. Interest in the scaling is also heightened because the exponent γ enters prominently into considerations of the relative contributions to the dynamics from pressure effects (e.g., activation barriers) vs. volume effects (e.g., free volume). Although this scaling is clearly of great practical use, a molecular understanding of the scaling remains elusive. Providing this molecular understanding would greatly enhance the utility of the empirically observed scaling in assisting the rational design of materials by describing how controllable molecular factors, such as monomer structures, interactions, flexibility, etc., influence the scaling exponent γ and, hence, the dynamics. Given the successes of the generalized entropy theory in elucidating the influence of molecular details on the universal properties of glass-forming polymers, this theory is extended here to investigate the thermodynamic scaling in polymer melts. The predictions of theory are in accord with the appearance of thermodynamic scaling for pressures not in excess of ~50 MPa. (The failure at higher pressures arises due to inherent limitations of a lattice model.) In line with arguments relating the magnitude of γ to the steepness of the repulsive part of the intermolecular potential, the abrupt, square-well nature of the lattice model interactions lead, as expected, to much larger values of the scaling exponent. Nevertheless, the theory is employed to study how individual molecular parameters affect the scaling exponent in order to extract a molecular understanding of the information content contained in the exponent. The chain

  11. Thermodynamic scaling of dynamics in polymer melts: Predictions from the generalized entropy theory

    NASA Astrophysics Data System (ADS)

    Xu, Wen-Sheng; Freed, Karl F.

    2013-06-01

    Many glass-forming fluids exhibit a remarkable thermodynamic scaling in which dynamic properties, such as the viscosity, the relaxation time, and the diffusion constant, can be described under different thermodynamic conditions in terms of a unique scaling function of the ratio ργ/T, where ρ is the density, T is the temperature, and γ is a material dependent constant. Interest in the scaling is also heightened because the exponent γ enters prominently into considerations of the relative contributions to the dynamics from pressure effects (e.g., activation barriers) vs. volume effects (e.g., free volume). Although this scaling is clearly of great practical use, a molecular understanding of the scaling remains elusive. Providing this molecular understanding would greatly enhance the utility of the empirically observed scaling in assisting the rational design of materials by describing how controllable molecular factors, such as monomer structures, interactions, flexibility, etc., influence the scaling exponent γ and, hence, the dynamics. Given the successes of the generalized entropy theory in elucidating the influence of molecular details on the universal properties of glass-forming polymers, this theory is extended here to investigate the thermodynamic scaling in polymer melts. The predictions of theory are in accord with the appearance of thermodynamic scaling for pressures not in excess of ˜50 MPa. (The failure at higher pressures arises due to inherent limitations of a lattice model.) In line with arguments relating the magnitude of γ to the steepness of the repulsive part of the intermolecular potential, the abrupt, square-well nature of the lattice model interactions lead, as expected, to much larger values of the scaling exponent. Nevertheless, the theory is employed to study how individual molecular parameters affect the scaling exponent in order to extract a molecular understanding of the information content contained in the exponent. The chain

  12. Integral equation theory of the structure and thermodynamics of polymer blends

    NASA Astrophysics Data System (ADS)

    Schweizer, Kenneth S.; Curro, John G.

    1989-10-01

    Our recently developed RISM integral equation theory of the structure and thermodynamics of homopolymer melts is generalized to polymer mixtures. The mean spherical approximation (MSA) closure to the generalized Ornstein-Zernike equations is employed, in conjunction with the neglect of explicit chain end effects and the assumption of ideality of intramolecular structure. The theory is developed in detail for binary blends, and the random phase approximation (RPA) form for concentration fluctuation scattering is rigorously obtained by enforcing incompressibility. A microscopic, wave vector-dependent expression for the effective chi parameter measured in small angle neutron scattering (SANS) experiments is derived in terms of the species-dependent direct correlation functions of the blend. The effective chi parameter is found to depend, in general, on thermodynamic state, intermolecular forces, intramolecular structure, degree of polymerization, and global architecture. The relationship between the mean field Flory-Huggins expression for the free energy of mixing and our RISM-MSA theory is determined, along with general analytical connections between the chi parameter and intermolecular pair correlations in the liquid. Detailed numerical applications to athermal and isotopic chain polymer blend models are presented for both the chi parameter and the structure. For athermal blends a negative, concentration-dependent chi parameter is found which decreases with density, structural asymmetry, and increases with molecular weight. For isotopic blends, the effective (positive) chi parameter is found to be strongly renormalized downward from its mean field enthalpic value by long range fluctuations in monomer concentration induced by polymeric connectivity and excluded volume. Both the renormalization and composition dependence of the chi parameter increase with chain length and proximity to the spinodal instability. The critical temperature is found to be proportional to

  13. Method of manufacturing a polymer-consolidated cadmium electrode for an alkaline storage cell, and an electrode obtained by the method

    SciTech Connect

    Brezillon, J.L.; Dauchier, J.M.

    1987-09-01

    A method is described of manufacturing a polymer-consolidated cadmium electrode for an alkaline storage cell, the method comprising the steps of: mixing the following ingredients in water: a gelling agent; cadmium and cadmium oxide in powder form constituting the active material; and a copolymer of carboxylated styrene-butadiene at a concenration lying in the range 0.5% to 3% by weight of active materials; coating the resulting paste one a metal current collector; drying the coated current collector; and subjecting the resulting assembly to a temperature lying in the range 120/sup 0/C to 150/sup 0/C for a period of a few minutes in order to cause the polymer to cross-link.

  14. How osmolytes influence hydrophobic polymer conformations: A unified view from experiment and theory.

    PubMed

    Mondal, Jagannath; Halverson, Duncan; Li, Isaac T S; Stirnemann, Guillaume; Walker, Gilbert C; Berne, Bruce J

    2015-07-28

    It is currently the consensus belief that protective osmolytes such as trimethylamine N-oxide (TMAO) favor protein folding by being excluded from the vicinity of a protein, whereas denaturing osmolytes such as urea lead to protein unfolding by strongly binding to the surface. Despite there being consensus on how TMAO and urea affect proteins as a whole, very little is known as to their effects on the individual mechanisms responsible for protein structure formation, especially hydrophobic association. In the present study, we use single-molecule atomic force microscopy and molecular dynamics simulations to investigate the effects of TMAO and urea on the unfolding of the hydrophobic homopolymer polystyrene. Incorporated with interfacial energy measurements, our results show that TMAO and urea act on polystyrene as a protectant and a denaturant, respectively, while complying with Tanford-Wyman preferential binding theory. We provide a molecular explanation suggesting that TMAO molecules have a greater thermodynamic binding affinity with the collapsed conformation of polystyrene than with the extended conformation, while the reverse is true for urea molecules. Results presented here from both experiment and simulation are in line with earlier predictions on a model Lennard-Jones polymer while also demonstrating the distinction in the mechanism of osmolyte action between protein and hydrophobic polymer. This marks, to our knowledge, the first experimental observation of TMAO-induced hydrophobic collapse in a ternary aqueous system. PMID:26170324

  15. Iso-flux tension propagation theory of driven polymer translocation: The role of initial configurations

    NASA Astrophysics Data System (ADS)

    Sarabadani, Jalal; Ikonen, Timo; Ala-Nissila, Tapio

    2014-12-01

    We investigate the dynamics of pore-driven polymer translocation by theoretical analysis and molecular dynamics (MD) simulations. Using the tension propagation theory within the constant flux approximation we derive an explicit equation of motion for the tension front. From this we derive a scaling relation for the average translocation time τ, which captures the asymptotic result τ ∝ N_0^{1+ν }, where N0 is the chain length and ν is the Flory exponent. In addition, we derive the leading correction-to-scaling term to τ and show that all terms of order N_0^{2ν } exactly cancel out, leaving only a finite-chain length correction term due to the effective pore friction, which is linearly proportional to N0. We use the model to numerically include fluctuations in the initial configuration of the polymer chain in addition to thermal noise. We show that when the cis side fluctuations are properly accounted for, the model not only reproduces previously known results but also considerably improves the estimates of the monomer waiting time distribution and the time evolution of the translocation coordinate s(t), showing excellent agreement with MD simulations.

  16. Entropy Theory of Polymer Glass-Formation in Variable Spatial Dimension

    NASA Astrophysics Data System (ADS)

    Xu, Wen-Sheng; Douglas, Jack; Freed, Karl

    The importance of packing frustration is broadly appreciated to be an important aspect of glass-formation. Recently, great interest has focused on using spatial dimensionality () as a theoretical tool for exploring this and other aspects of glass-forming liquids. We explore glass-formation in variable based on the generalized entropy theory, a synthesis of the Adam-Gibbs model with direct computation of the configurational entropy of polymer fluids using an established analytical statistical thermodynamic model. We find that structural relaxation in the fluid state asymptotically becomes Arrhenius in the limit and that the fluid transforms upon sufficient cooling above a critical dimension near into a dense amorphous state with a finite positive residual configurational entropy. The GET also predicts the variation with of measures of fragility and of the characteristic temperatures of glass-formation demarking the onset , middle , and end , of the broad glass transition. Direct computations of the isothermal compressibility and thermal expansion coefficient, which are physical measures of packing frustration, demonstrate that these fluid properties strongly correlate with the fragility of glass-formation. Back to three dimensions, we deduce apparently universal relationships between , a measure of the breadth of the glass-formation and both the isothermal compressibility and thermal expansion coefficient of polymer melts at .

  17. Microscopic Theory for Entangled Polymer Dynamics in Rod-Sphere Nanocomposites

    NASA Astrophysics Data System (ADS)

    Yamamoto, Umi; Schweizer, Kenneth

    2014-03-01

    We have developed a self-consistent microscopic theory for the long-time dynamics of needles in an array of static spherical fillers. The approach exactly enforces the dynamical two-body rod topological uncrossability and sphere impenetrability constraints, leading to a generalized concept of entanglements that includes the filler excluded volume effect. How the diffusion anisotropy (transverse versus longitudinal motion) depends on the filler-needle aspect ratio, polymer concentration, and filler volume fraction is established. Due to the steric blocking of the longitudinal reptative motion by obstacles, a literal localization transition is predicted that is generically controlled by the ratio of filler diameter to the pure polymer tube diameter or needle length. For a window of filler sizes and loadings, the needle is predicted to diffuse via a ``renormalized'' reptation dynamics where the tube is compressed and the longitudinal motion is retarded in a manner that depends on all system variables. At high filler volume fractions the needle diffusivity is strongly suppressed, and localization ultimately occurs in the unentangled needle regime. Generalization of the approach to treat mobile fillers, flexible chains, and nonrandom microstructure is also possible.

  18. How osmolytes influence hydrophobic polymer conformations: A unified view from experiment and theory

    PubMed Central

    Mondal, Jagannath; Halverson, Duncan; Li, Isaac T. S.; Stirnemann, Guillaume; Walker, Gilbert C.; Berne, Bruce J.

    2015-01-01

    It is currently the consensus belief that protective osmolytes such as trimethylamine N-oxide (TMAO) favor protein folding by being excluded from the vicinity of a protein, whereas denaturing osmolytes such as urea lead to protein unfolding by strongly binding to the surface. Despite there being consensus on how TMAO and urea affect proteins as a whole, very little is known as to their effects on the individual mechanisms responsible for protein structure formation, especially hydrophobic association. In the present study, we use single-molecule atomic force microscopy and molecular dynamics simulations to investigate the effects of TMAO and urea on the unfolding of the hydrophobic homopolymer polystyrene. Incorporated with interfacial energy measurements, our results show that TMAO and urea act on polystyrene as a protectant and a denaturant, respectively, while complying with Tanford–Wyman preferential binding theory. We provide a molecular explanation suggesting that TMAO molecules have a greater thermodynamic binding affinity with the collapsed conformation of polystyrene than with the extended conformation, while the reverse is true for urea molecules. Results presented here from both experiment and simulation are in line with earlier predictions on a model Lennard–Jones polymer while also demonstrating the distinction in the mechanism of osmolyte action between protein and hydrophobic polymer. This marks, to our knowledge, the first experimental observation of TMAO-induced hydrophobic collapse in a ternary aqueous system. PMID:26170324

  19. Immersion energy and polymer-mediated depletion interactions between nanocolloids as studied by analytic self-consistent field theory

    NASA Astrophysics Data System (ADS)

    Chervanyov, A. I.; Heinrich, G.

    2012-08-01

    By applying the Edwards self-consistent field theory, we calculate the polymer density and free energy excesses caused by the presence of nanocolloids in the excluded volume polymer system. Using the obtained results, we have calculated the depletion potential U as a function of the separation between colloids, colloid radius, polymer volume fraction, and polymer gyration radius. Upon analyzing the obtained results against the known exact asymptotic small-separation limit and scaling relations, we propose an approximate expression for U that builds upon our exact result. This expression is shown to give excellent agreement with Monte Carlo simulations. Reliability of the derived analytical expression for the depletion potential and its relation to the previous theoretical and simulation work are thoroughly discussed.

  20. Pacific Northwest National Laboratory collaboration with Moltech Corporation to manufacture lithium polymer batteries (C/PNL/061). Final project report

    SciTech Connect

    Affinito, J.D.

    1996-08-01

    It was shown that all 7 of the layers of Moltech`s Li polymer battery are compatible with simultaneous, in-line, vacuum deposition onto a flexible plastic substrate via PNNL`s PML and LML technology. All the materials, including Li, could be deposited in a single pass without melting the substrate. Two problems were encountered and are discussed.

  1. Supporting capacity sharing in the cloud manufacturing environment based on game theory and fuzzy logic

    NASA Astrophysics Data System (ADS)

    Argoneto, Pierluigi; Renna, Paolo

    2016-02-01

    This paper proposes a Framework for Capacity Sharing in Cloud Manufacturing (FCSCM) able to support the capacity sharing issue among independent firms. The success of geographical distributed plants depends strongly on the use of opportune tools to integrate their resources and demand forecast in order to gather a specific production objective. The framework proposed is based on two different tools: a cooperative game algorithm, based on the Gale-Shapley model, and a fuzzy engine. The capacity allocation policy takes into account the utility functions of the involved firms. It is shown how the capacity allocation policy proposed induces all firms to report truthfully their information about their requirements. A discrete event simulation environment has been developed to test the proposed FCSCM. The numerical results show the drastic reduction of unsatisfied capacity obtained by the model of cooperation implemented in this work.

  2. Wall-fluid and liquid-gas interfaces of model colloid-polymer mixtures by simulation and theory.

    PubMed

    Fortini, Andrea; Dijkstra, Marjolein; Schmidt, Matthias; Wessels, Paul P F

    2005-05-01

    We perform a study of the interfacial properties of a model suspension of hard sphere colloids with diameter sigma(c) and nonadsorbing ideal polymer coils with diameter sigma(p) . For the mixture in contact with a planar hard wall, we obtain from simulations the wall-fluid interfacial free energy, gamma(wf) , for size ratios q =sigma(p)/sigma(c) =0.6 and 1, using thermodynamic integration, and study the (excess) adsorption of colloids, Gamma(c) , and of polymers, Gamma(p) , at the hard wall. The interfacial tension of the free liquid-gas interface, gamma(lg) , is obtained following three different routes in simulations: (i) from studying the system size dependence of the interfacial width according to the predictions of capillary wave theory, (ii) from the probability distribution of the colloid density at coexistence in the grand canonical ensemble, and (iii) for state points where the colloidal liquid wets the wall completely, from Young's equation relating gamma(lg) to the difference of wall-liquid and wall-gas interfacial tensions, gamma(wl)-gamma(wg) . In addition, we calculate gamma(wf) ,Gamma(c) , and Gamma(p) using density functional theory and a scaled particle theory based on free volume theory. Good agreement is found between the simulation results and those from density functional theory, while the results from scaled particle theory quantitatively deviate but reproduce some essential features. Simulation results for gamma(lg) obtained from the three different routes are all in good agreement. Density functional theory predicts gamma(lg) with good accuracy for high polymer reservoir packing fractions, but yields deviations from the simulation results close to the critical point. PMID:16089531

  3. The role of intramolecular barriers on the glass transition of polymers: Computer simulations versus mode coupling theory.

    PubMed

    Bernabei, Marco; Moreno, Angel J; Colmenero, Juan

    2009-11-28

    We present computer simulations of a simple bead-spring model for polymer melts with intramolecular barriers. By systematically tuning the strength of the barriers, we investigate their role on the glass transition. Dynamic observables are analyzed within the framework of the mode coupling theory (MCT). Critical nonergodicity parameters, critical temperatures, and dynamic exponents are obtained from consistent fits of simulation data to MCT asymptotic laws. The so-obtained MCT lambda-exponent increases from standard values for fully flexible chains to values close to the upper limit for stiff chains. In analogy with systems exhibiting higher-order MCT transitions, we suggest that the observed large lambda-values arise form the interplay between two distinct mechanisms for dynamic arrest: general packing effects and polymer-specific intramolecular barriers. We compare simulation results with numerical solutions of the MCT equations for polymer systems, within the polymer reference interaction site model (PRISM) for static correlations. We verify that the approximations introduced by the PRISM are fulfilled by simulations, with the same quality for all the range of investigated barrier strength. The numerical solutions reproduce the qualitative trends of simulations for the dependence of the nonergodicity parameters and critical temperatures on the barrier strength. In particular, the increase in the barrier strength at fixed density increases the localization length and the critical temperature. However the qualitative agreement between theory and simulation breaks in the limit of stiff chains. We discuss the possible origin of this feature. PMID:19947689

  4. Application of high performance computing to automotive design and manufacturing: Composite materials modeling task technical manual for constitutive models for glass fiber-polymer matrix composites

    SciTech Connect

    Simunovic, S; Zacharia, T

    1997-11-01

    This report provides a theoretical background for three constitutive models for a continuous strand mat (CSM) glass fiber-thermoset polymer matrix composite. The models were developed during fiscal years 1994 through 1997 as a part of the Cooperative Research and Development Agreement, "Application of High-Performance Computing to Automotive Design and Manufacturing." The full derivation of constitutive relations in the framework of the continuum program DYNA3D and have been used for the simulation and impact analysis of CSM composite tubes. The analysis of simulation and experimental results show that the model based on strain tensor split yields the most accurate results of the three implemented models. The parameters used in the models and their derivation from the physical tests are documented.

  5. The viability and limitations of percolation theory in modeling the electrical behavior of carbon nanotube-polymer composites

    NASA Astrophysics Data System (ADS)

    Xu, S.; Rezvanian, O.; Peters, K.; Zikry, M. A.

    2013-04-01

    A new modeling method has been proposed to investigate how the electrical conductivity of carbon nanotube (CNT) reinforced polymer composites are affected by tunneling distance, volume fraction, and tube aspect ratios. A search algorithm and an electrical junction identification method was developed with a percolation approach to determine conductive paths for three-dimensional (3D) carbon nanotube arrangements and to account for electron tunneling effects. The predicted results are used to understand the limitations of percolation theory and experimental measurements and observations, and why percolation theory breaks down for specific CNT arrangements.

  6. Modeling of hydro-thermo-mechanical behavior of Nafion NRE212 for Polymer Electrolyte Membrane Fuel Cells using the Finite Viscoplasticity Theory Based on Overstress for Polymers (FVBOP)

    NASA Astrophysics Data System (ADS)

    Colak, Ozgen U.; Acar, Alperen

    2013-08-01

    The primary aim of this work is to present the modifications made to the Finite Viscoplasticity Theory Based on Overstress for Polymers (FVBOP). This is a unified state variable theory and the proposed changes are designed to account for humidity and temperature effects relevant to the modeling of the hydrothermal deformation behavior of ionomer membranes used in Polymer Electrolyte Membrane Fuel Cells (PEMFC). Towards that end, the flow function, which is responsible for conferring rate dependency in FVBOP, is modified. A secondary objective of this work was to investigate the feasibility of using the storage modulus obtained by Dynamic Mechanical Analysis (DMA) in place of the elasticity modulus obtained from conventional tensile/compressive tests, and find the correlation between the storage modulus and the elasticity modulus. The numerical simulations were juxtaposed against data from tensile monotonic loading and unloading experiments on perfluorosulfonic acid (PFSA) membrane Nafion NRE212 samples which are used extensively as a membrane material in PEMFC. The deformation behavior was modeled at four different temperatures (298, 323, 338, and 353 K—all values below the glass transition temperature of Nafion) and at three water content levels (3, 7 and 8 % swelling). The effects of strain rate, temperature, and hydration were captured well with the modified FVBOP model.

  7. Analysis of surface segregation in polymer mixtures: A combination of mean field and statistical associated fluid theories

    NASA Astrophysics Data System (ADS)

    Krawczyk, Jaroslaw; Croce, Salvatore; Chakrabarti, Buddhapriya; Tasche, Jos

    The surface segregation in polymer mixtures remains a challenging problem for both academic exploration as well as industrial applications. Despite its ubiquity and several theoretical attempts a good agreement between computed and experimentally observed profiles has not yet been achieved. A simple theoretical model proposed in this context by Schmidt and Binder combines Flory-Huggins free energy of mixing with the square gradient theory of wetting of a wall by fluid. While the theory gives us a qualitative understanding of the surface induced segregation and the surface enrichment it lacks the quantitative comparison with the experiment. The statistical associating fluid theory (SAFT) allows us to calculate accurate free energy for a real polymeric materials. In an earlier work we had shown that increasing the bulk modulus of a polymer matrix through which small molecules migrate to the free surface causes reduction in the surface migrant fraction using Schmidt-Binder and self-consistent field theories. In this work we validate this idea by combining mean field theories and SAFT to identify parameter ranges where such an effect should be observable. Department of Molecular Physics, Łódź University of Technology, Żeromskiego 116, 90-924 Łódź, Poland.

  8. A statistical theory of cosolvent-induced coil-globule transitions in dilute polymer solution

    NASA Astrophysics Data System (ADS)

    Budkov, Yu. A.; Kolesnikov, A. L.; Georgi, N.; Kiselev, M. G.

    2014-07-01

    We present a statistical model of a dilute polymer solution in good solvent in the presence of low-molecular weight cosolvent. We investigate the conformational changes of the polymer induced by a change of the cosolvent concentration and the type of interaction between the cosolvent and the polymer. We describe the polymer in solution by the Edwards model, where the partition function of the polymer chain with a fixed radius of gyration is described in the framework of the mean-field approximation. The contributions of polymer-cosolvent and the cosolvent-cosolvent interactions in the total free energy are treated also within the mean-field approximation. For convenience we separate the system volume on two parts: the volume occupied by the polymer chain expressed through its gyration volume and the bulk solution. Considering the equilibrium between the two subvolumes we obtain the total free energy of the solution as a function of radius of gyration and the cosolvent concentration within gyration volume. After minimization of the total free energy with respect to its arguments we obtain a system of coupled equations with respect to the radius of gyration of the polymer chain and the cosolvent concentration within the gyration volume. Varying the interaction strength between polymer and cosolvent we show that the polymer collapse occurs in two cases—either when the interaction between polymer and cosolvent is repulsive or when the interaction is attractive. The reported effects could be relevant for different disciplines where conformational transitions of macromolecules in the presence of a cosolvent are of interest, in particular in biology, chemistry, and material science.

  9. Smart polymers as surface modifiers for bioanalytical devices and biomaterials: theory and practice

    NASA Astrophysics Data System (ADS)

    Ivanov, A. E.; Zubov, V. P.

    2016-06-01

    Smart, or responsive polymers can reversibly change their state of aggregation, thus switching from water-soluble to insoluble state, in response to minor changes in temperature, pH or solvent composition. Grafting of these polymers to solid surfaces imparts the surfaces with controllable wettability and adsorption behaviour. The review summarizes the theoretical models and the results of physical measurements of the conformational transitions in grafted polymer chains and polymer brushes. Primary attention is paid to the grafting density and the length and spatial arrangement of grafted chains, the role of polystyrene, organosilane or alkanethiol sublayers and their effects on adsorption of proteins and adhesion of cells. The key applications of grafted smart polymers such as cell culture and tissue engineering, cell and protein separation, biosensing and targeted drug delivery are surveyed. The bibliography includes 174 references.

  10. Complex microstructures of ABC triblock copolymer thin films directed by polymer brushes based on self-consistent field theory.

    PubMed

    Jiang, Zhibin; Xu, Chang; Qiu, Yu Dong; Wang, Xiaoliang; Zhou, Dongshan; Xue, Gi

    2014-01-01

    The morphology and the phase diagram of ABC triblock copolymer thin film directed by polymer brushes are investigated by the self-consistent field theory in three dimensions. The polymer brushes coated on the substrate can be used as a good soft template to tailor the morphology of the block copolymer thin films compared with those on the hard substrates. The polymer brush is identical with the middle block B. By continuously changing the composition of the block copolymer, the phase diagrams are constructed for three cases with the fixed film thickness and the brush density: identical interaction parameters, frustrated and non-frustrated cases. Some ordered complex morphologies are observed: parallel lamellar phase with hexagonally packed pores at surfaces (LAM3 (ll) -HFs), perpendicular lamellar phase with cylinders at the interface (LAM(⊥)-CI), and perpendicular hexagonally packed cylinders phase with rings at the interface (C2 (⊥)-RI). A desired direction (perpendicular or parallel to the coated surfaces) of lamellar phases or cylindrical phases can be obtained by varying the composition and the interactions between different blocks. The phase diagram of ABC triblock copolymer thin film wetted between the polymer brush-coated surfaces is very useful in designing the directed pattern of ABC triblock copolymer thin film. PMID:25114650

  11. Modeling helical polymer brushes using self-consistent field theory (SCFT)

    NASA Astrophysics Data System (ADS)

    Mahalik, Jyoti; Sumpter, Bobby; Kumar, Rajeev

    We investigate structure of helical polymer brushes in terms of segment density distribution and local helical ordering using SCFT. A flexible chain model with vector potential was used to model liquid crystalline-like ordering in the brushes. The effects of surface grafting density, polymer molecular weight and the solvent quality on the brush structure were investigated. For densely grafted polymer brushes or the brushes made up of high molecular weight polymers, immersed in good quality solvent, stronger orientational ordering was found near the edge of the brushes (i.e., far from the grafting surface). Furthermore, an increase in the orientational ordering near the grafted end was found with decrease in solvent quality or decrease in molecular weight and decrease in surface grafting density. Computer Science and Mathematics Division, Oak Ridge National Laboratory.

  12. Photovoltaic manufacturing technology monolithic amorphous silicon modules on continuous polymer substrates: Final technical report, July 5, 1995--December 31, 1999

    SciTech Connect

    Jeffrey, F.

    2000-03-28

    Iowa Thin Film Technologies is completing a three-phase program that has increased throughput and decreased costs in nearly all aspects of its thin-film photovoltaic manufacturing process. The overall manufacturing costs have been reduced by 61 percent through implementation of the improvements developed under this program. Development of the ability to use a 1-mil substrate, rather than the standard 2-mil substrate, results in a 50 percent cost-saving for this material. Process development on a single-pass amorphous silicon deposition system has resulted in a 37 percent throughput improvement. A wide range of process and machine improvements have been implemented on the transparent conducting oxide deposition system. These include detailed parameter optimization of deposition temperatures, process gas flows, carrier gas flows, and web speeds. An overall process throughput improvement of 275 percent was achieved based on this work. The new alignment technique was developed for the laser scriber and printer systems, which improved registration accuracy from 100 microns to 10 microns. The new technique also reduced alignment time for these registration systems significantly. This resulted in a throughput increase of 75 percent on the scriber and 600 percent on the printer. Automated techniques were designed and implemented for the module assembly processes. These include automated busbar attachment, roll-based lamination, and automated die cutting of finished modules. These processes were previously done by hand labor. Throughput improvements ranged from 200 percent to 1200 percent, relative to hand labor rates. A wide range of potential encapsulation materials were evaluated for suitability in a roll lamination process and for cost-effectiveness. A combination material was found that has a cost that is only 10 percent of the standard EVA/Tefzel cost and is suitable for medium-lifetime applications. The 20-year lifetime applications still require the more expensive

  13. An injection molding process for manufacturing highly porous and interconnected biodegradable polymer matrices for use as tissue engineering scaffolds.

    PubMed

    Kramschuster, Adam; Turng, Lih-Sheng

    2010-02-01

    In this research, injection molding was combined with a novel material combination, supercritical fluid processing, and particulate leaching techniques to produce highly porous and interconnected structures that have the potential to act as scaffolds for tissue engineering applications. The foamed structures, molded with polylactide (PLA) and polyvinyl alcohol (PVOH) with salt as the particulate, were processed without the aid of organic solvents, which can be detrimental to tissue growth. The pore size in the scaffolds is controlled by salt particulates and interconnectivity is achieved by the co-continuous blending morphology of biodegradable PLA matrix with water-soluble PVOH. Carbon dioxide (CO(2)) at the supercritical state is used to serve as a plasticizer, thereby imparting moldability of blends even with an ultra high salt particulate content, and allows the use of low processing temperatures, which are desirable for temperature-sensitive biodegradable polymers. Interconnected pores of approximately 200 microm in diameter and porosities of approximately 75% are reported and discussed. PMID:19957359

  14. Ab initio molecular dynamics with nuclear quantum effects at classical cost: Ring polymer contraction for density functional theory.

    PubMed

    Marsalek, Ondrej; Markland, Thomas E

    2016-02-01

    Path integral molecular dynamics simulations, combined with an ab initio evaluation of interactions using electronic structure theory, incorporate the quantum mechanical nature of both the electrons and nuclei, which are essential to accurately describe systems containing light nuclei. However, path integral simulations have traditionally required a computational cost around two orders of magnitude greater than treating the nuclei classically, making them prohibitively costly for most applications. Here we show that the cost of path integral simulations can be dramatically reduced by extending our ring polymer contraction approach to ab initio molecular dynamics simulations. By using density functional tight binding as a reference system, we show that our ring polymer contraction scheme gives rapid and systematic convergence to the full path integral density functional theory result. We demonstrate the efficiency of this approach in ab initio simulations of liquid water and the reactive protonated and deprotonated water dimer systems. We find that the vast majority of the nuclear quantum effects are accurately captured using contraction to just the ring polymer centroid, which requires the same number of density functional theory calculations as a classical simulation. Combined with a multiple time step scheme using the same reference system, which allows the time step to be increased, this approach is as fast as a typical classical ab initio molecular dynamics simulation and 35× faster than a full path integral calculation, while still exactly including the quantum sampling of nuclei. This development thus offers a route to routinely include nuclear quantum effects in ab initio molecular dynamics simulations at negligible computational cost. PMID:26851913

  15. Application of the integral equation theory of polymers: Distribution function, chemical potential, and mean expansion coefficient

    NASA Astrophysics Data System (ADS)

    Gan, Hin Hark; Eu, Byung Chan

    1993-09-01

    A recursive integral equation for the intramolecular correlation function of an isolated linear polymer of N bonds is derived from the integral equations presented in the preceding paper. The derivation basically involves limiting the density of the polymer to zero so that polymers do not interact with each other, and thus taking into account the intramolecular part only. The integral equation still has the form of a generalized Percus-Yevick integral equation. The intramolecular correlation function of a polymer of N bonds is recursively generated by means of it from those of polymers of 2, 3,..., (N-1) bonds. The end-to-end distance distribution functions are computed by using the integral equation for various chain lengths, temperatures, and bond lengths in the case of a repulsive soft-sphere potential. Numerical solutions of the recursive integral equation yield universal exponents for the mean square end-to-end distance in two and three dimensions with values which are close to the Flory results: 0.77 and 0.64 vs Flory's values 0.75 and 0.6 for two and three dimensions, respectively. The intramolecular correlation functions computed can be fitted with displaced Gaussian forms. The N dependence of the internal chemical potential is found to saturate after some value of N depending on the ratio of the bond length to the bead radius.

  16. Theory of competitive solvation of polymers by two solvents and entropy-enthalpy compensation in the solvation free energy upon dilution with the second solvent

    NASA Astrophysics Data System (ADS)

    Dudowicz, Jacek; Freed, Karl F.; Douglas, Jack F.

    2015-06-01

    We develop a statistical mechanical lattice theory for polymer solvation by a pair of relatively low molar mass solvents that compete for binding to the polymer backbone. A theory for the equilibrium mixture of solvated polymer clusters {AiBCj} and free unassociated molecules A, B, and C is formulated in the spirit of Flory-Huggins mean-field approximation. This theoretical framework enables us to derive expressions for the boundaries for phase stability (spinodals) and other basic properties of these polymer solutions: the internal energy U, entropy S, specific heat CV, extent of solvation Φsolv, average degree of solvation , and second osmotic virial coefficient B 2 as functions of temperature and the composition of the mixture. Our theory predicts many new phenomena, but the current paper applies the theory to describe the entropy-enthalpy compensation in the free energy of polymer solvation, a phenomenon observed for many years without theoretical explanation and with significant relevance to liquid chromatography and other polymer separation methods.

  17. Theory of competitive solvation of polymers by two solvents and entropy-enthalpy compensation in the solvation free energy upon dilution with the second solvent.

    PubMed

    Dudowicz, Jacek; Freed, Karl F; Douglas, Jack F

    2015-06-01

    We develop a statistical mechanical lattice theory for polymer solvation by a pair of relatively low molar mass solvents that compete for binding to the polymer backbone. A theory for the equilibrium mixture of solvated polymer clusters {AiBCj} and free unassociated molecules A, B, and C is formulated in the spirit of Flory-Huggins mean-field approximation. This theoretical framework enables us to derive expressions for the boundaries for phase stability (spinodals) and other basic properties of these polymer solutions: the internal energy U, entropy S, specific heat CV, extent of solvation Φsolv, average degree of solvation 〈Nsolv〉, and second osmotic virial coefficient B2 as functions of temperature and the composition of the mixture. Our theory predicts many new phenomena, but the current paper applies the theory to describe the entropy-enthalpy compensation in the free energy of polymer solvation, a phenomenon observed for many years without theoretical explanation and with significant relevance to liquid chromatography and other polymer separation methods. PMID:26049523

  18. Roll to Roll Electric Field "Z" Alignment of Nanoparticles from Polymer Solutions for Manufacturing Multifunctional Capacitor Films.

    PubMed

    Guo, Yuanhao; Batra, Saurabh; Chen, Yuwei; Wang, Enmin; Cakmak, Miko

    2016-07-20

    A roll to roll continuous processing method is developed for vertical alignment ("Z" alignment) of barium titanate (BaTiO3) nanoparticle columns in polystyrene (PS)/toluene solutions. This is accomplished by applying an electric field to a two-layer solution film cast on a carrier: one is the top sacrificial layer contacting the electrode and the second is the polymer solution dispersed with BaTiO3 particles. Flexible Teflon coated mesh is utilized as the top electrode that allows the evaporation of solvent through the openings. The kinetics of particle alignment and chain buckling is studied by the custom-built instrument measuring the real time optical light transmission during electric field application and drying steps. The nanoparticles dispersed in the composite bottom layer form chains due to dipole-dipole interaction under an applied electric field. In relatively weak electric fields, the particle chain axis tilts away from electric field direction due to bending caused by the shrinkage of the film during drying. The use of strong electric fields leads to maintenance of alignment of particle chains parallel to the electric field direction overcoming the compression effect. At the end of the process, the surface features of the top porous electrodes are imprinted at the top of the top sacrificial layer. By removing this layer a smooth surface film is obtained. The nanocomposite films with "Z" direction alignment of BaTiO3 particles show substantially increased dielectric permittivity in the thickness direction for enhancing the performance of capacitors. PMID:27322765

  19. Macro- and micro-nutrient release characteristics of three polymer-coated fertilizers: Theory and measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In spite of several published studies we have an incomplete understanding of the ion release mechanisms and characteristics of primary polymer-coated fertilizer (PCF) technologies. Here we extend current conceptual models describing release mechanisms and describe the critical effects of substrate m...

  20. Unified force-level theory of multiscale transient localization and emergent elasticity in polymer solutions and melts

    NASA Astrophysics Data System (ADS)

    Dell, Zachary E.; Schweizer, Kenneth S.

    A unified, microscopic, theoretical understanding of polymer dynamics in concentrated liquids from segmental to macromolecular scales remains an open problem. We have formulated a statistical mechanical theory for this problem that explicitly accounts for intra- and inter-molecular forces at the Kuhn segment level. The theory is self-consistently closed at the level of a matrix of dynamical second moments of a tagged chain. Two distinct regimes of isotropic transient localization are predicted. In semidilute solutions, weak localization is predicted on a mesoscopic length scale between segment and chain scales which is a power law function of the invariant packing length. This is consistent with the breakdown of Rouse dynamics and the emergence of entanglements. The chain structural correlations in the dynamically arrested state are also computed. In dense melts, strong localization is predicted on a scale much smaller than the segment size which is weakly dependent on chain connectivity and signals the onset of glassy dynamics. Predictions of the dynamic plateau shear modulus are consistent with the known features of emergent rubbery and glassy elasticity. Generalizations to treat the effects of chemical crosslinking and physical bond formation in polymer gels are possible.

  1. Ring-polymer instanton theory of electron transfer in the nonadiabatic limit

    SciTech Connect

    Richardson, Jeremy O.

    2015-10-07

    We take the golden-rule instanton method derived in the previous paper [J. O. Richardson, R. Bauer, and M. Thoss, J. Chem. Phys. 143, 134115 (2015)] and reformulate it using a ring-polymer instanton approach. This gives equations which can be used to compute the rates of electron-transfer reactions in the nonadiabatic (golden-rule) limit numerically within a semiclassical approximation. The multidimensional ring-polymer instanton trajectories are obtained efficiently by minimization of the action. In this form, comparison with Wolynes’ quantum instanton method [P. G. Wolynes, J. Chem. Phys. 87, 6559 (1987)] is possible and we show that our semiclassical approach is the steepest-descent limit of this method. We discuss advantages and disadvantages of both methods and give examples of where the new approach is more accurate.

  2. Self-consistent field theory of tethered polymers: One dimensional, three dimensional, strong stretching theories and the effects of excluded-volume-only interactions

    SciTech Connect

    Suo, Tongchuan Whitmore, Mark D.

    2014-11-28

    We examine end-tethered polymers in good solvents, using one- and three-dimensional self-consistent field theory, and strong stretching theories. We also discuss different tethering scenarios, namely, mobile tethers, fixed but random ones, and fixed but ordered ones, and the effects and important limitations of including only binary interactions (excluded volume terms). We find that there is a “mushroom” regime in which the layer thickness is independent of the tethering density, σ, for systems with ordered tethers, but we argue that there is no such plateau for mobile or disordered anchors, nor is there one in the 1D theory. In the other limit of brushes, all approaches predict that the layer thickness scales linearly with N. However, the σ{sup 1/3} scaling is a result of keeping only excluded volume interactions: when the full potential is included, the dependence is faster and more complicated than σ{sup 1/3}. In fact, there does not appear to be any regime in which the layer thickness scales in the combination Nσ{sup 1/3}. We also compare the results for two different solvents with each other, and with earlier Θ solvent results.

  3. Self-consistent field theory of tethered polymers: One dimensional, three dimensional, strong stretching theories and the effects of excluded-volume-only interactions

    NASA Astrophysics Data System (ADS)

    Suo, Tongchuan; Whitmore, Mark D.

    2014-11-01

    We examine end-tethered polymers in good solvents, using one- and three-dimensional self-consistent field theory, and strong stretching theories. We also discuss different tethering scenarios, namely, mobile tethers, fixed but random ones, and fixed but ordered ones, and the effects and important limitations of including only binary interactions (excluded volume terms). We find that there is a "mushroom" regime in which the layer thickness is independent of the tethering density, σ, for systems with ordered tethers, but we argue that there is no such plateau for mobile or disordered anchors, nor is there one in the 1D theory. In the other limit of brushes, all approaches predict that the layer thickness scales linearly with N. However, the σ1/3 scaling is a result of keeping only excluded volume interactions: when the full potential is included, the dependence is faster and more complicated than σ1/3. In fact, there does not appear to be any regime in which the layer thickness scales in the combination Nσ1/3. We also compare the results for two different solvents with each other, and with earlier Θ solvent results.

  4. Phenomenological theory of the dynamics of polymer melts. I. Analytic treatment of self-diffusion

    NASA Astrophysics Data System (ADS)

    Skolnick, Jeffrey; Yaris, Robert; Kolinski, Andrzej

    1988-01-01

    In the context of dynamic Monte Carlo (MC) simulations on dense collections of polymer chains confined to a cubic lattice, the nature of the dynamic entanglements giving rise to the degree of polymerization n, dependence of the self-diffusion constant D˜n-2 is examined. Consistent with our previous simulation results, which failed to find evidence for reptation as the dominant mechanism of polymer melt motion [J. Chem. Phys. 86, 1567, 7164, 7174 (1987)], long-lived dynamic entanglement contacts between pairs of segments belonging to different chains are extremely rare and are mobile with respect to the laboratory fixed frame. It is suggested that dynamic entanglements involve the dragging of one chain by another through the melt for times on the order of the terminal relaxation time of the end-to-end vector. Employing the physical description provided by the MC simulation, the general expression of Hess [Macromolecules 19, 1395 (1986)] for the friction constant increment experienced by a polymer due to the other polymers forms the basis of a phenomenological derivation of D˜n-2 for monodisperse melts that does not require the existence of reptation. Rather, such behavior is dependent on the relatively benign assumptions that the long distance global motions of the chains are uncorrelated, that the dynamic contacts can be truncated at the pair level, and that the propagator describing the evolution between dynamic contacts contains a free Rouse chain component. The mean distance between dynamic entanglements is predicted to depend inversely on concentration, in agreement with experiment. Moreover, as the free Rouse component is frozen out, for chains greater than an entanglement length ne, a molecular weight independent glass transition is predicted. Extension to bidisperse melts predicts that the probe diffusion coefficient Dp depends on the matrix degree of polymerization, nm, as n-1m. Finally, comparison is made between the theoretical expressions and MC

  5. Theory for polymer analysis using nanopore-based single-molecule mass spectrometry

    PubMed Central

    Reiner, Joseph E.; Kasianowicz, John J.; Nablo, Brian J.; Robertson, Joseph W. F.

    2010-01-01

    Nanometer-scale pores have demonstrated potential for the electrical detection, quantification, and characterization of molecules for biomedical applications and the chemical analysis of polymers. Despite extensive research in the nanopore sensing field, there is a paucity of theoretical models that incorporate the interactions between chemicals (i.e., solute, solvent, analyte, and nanopore). Here, we develop a model that simultaneously describes both the current blockade depth and residence times caused by individual poly(ethylene glycol) (PEG) molecules in a single α-hemolysin ion channel. Modeling polymer-cation binding leads to a description of two significant effects: a reduction in the mobile cation concentration inside the pore and an increase in the affinity between the polymer and the pore. The model was used to estimate the free energy of formation for K+-PEG inside the nanopore (≈-49.7 meV) and the free energy of PEG partitioning into the nanopore (≈0.76 meV per ethylene glycol monomer). The results suggest that rational, physical models for the analysis of analyte-nanopore interactions will develop the full potential of nanopore-based sensing for chemical and biological applications. PMID:20566890

  6. Solvation effects for polymers at an interface: a hybrid self-consistent field-density functional theory approach.

    PubMed

    Bryk, Paweł; MacDowell, Luis G

    2011-11-28

    Using polyatomic density functional theory of Kierlik and Rosinberg, we show that Wertheim's thermodynamic perturbation theory (TPT) incorporates solvation effects in a systematic, although simplified form. We derive two approximate solvation potentials, which require the knowledge of the correlation function in the reference unbonded fluid only. The theoretical predictions are tested against many-chain Monte Carlo simulations for moderate chain lengths. The predictions of the end-to-end distance in the bulk are in a reasonable agreement with simulations for the TPT(M-1) approximation, while the simpler TPT2_e approximation leads to the solvation potential that is shorter ranged and considerably less accurate. The resulting conformations are used in the subsequent self-consistent field theory calculations of hard-sphere polymers at a hard wall. While the incorporation of the solvation effects has little impact on the density profiles, the predictions of the components of the end-to-end distance vector as a function of the distance to the wall are much improved. PMID:22128953

  7. Hierarchies in eukaryotic genome organization: Insights from polymer theory and simulations

    PubMed Central

    2011-01-01

    Eukaryotic genomes possess an elaborate and dynamic higher-order structure within the limiting confines of the cell nucleus. Knowledge of the physical principles and the molecular machinery that govern the 3D organization of this structure and its regulation are key to understanding the relationship between genome structure and function. Elegant microscopy and chromosome conformation capture techniques supported by analysis based on polymer models are important steps in this direction. Here, we review results from these efforts and provide some additional insights that elucidate the relationship between structure and function at different hierarchical levels of genome organization. PMID:21595865

  8. Simulations on the number of entanglements of a polymer network using knot theory.

    PubMed

    Michalke, W; Lang, M; Kreitmeier, S; Göritz, D

    2001-07-01

    Polymer networks, created on the computer using the Bond-Fluctuation-Algorithm, offer the possibility to count the number of entanglements. We generated networks consisting of 5000 chains that were cross linked at their end groups via tetra-functional cross linkers. The analysis of the topology was performed by computing the Homfly polynomial of the entanglements offering a much more precise determination of the knot and entanglement type than the Gaussian linking number. It also allows us to determine the influence of Brunnian links. Results concerning the connection between the chain length and the number of entanglements are shown. PMID:11461310

  9. Implementation of Improved Transverse Shear Calculations and Higher Order Laminate Theory Into Strain Rate Dependent Analyses of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Zhu, Lin-Fa; Kim, Soo; Chattopadhyay, Aditi; Goldberg, Robert K.

    2004-01-01

    A numerical procedure has been developed to investigate the nonlinear and strain rate dependent deformation response of polymer matrix composite laminated plates under high strain rate impact loadings. A recently developed strength of materials based micromechanics model, incorporating a set of nonlinear, strain rate dependent constitutive equations for the polymer matrix, is extended to account for the transverse shear effects during impact. Four different assumptions of transverse shear deformation are investigated in order to improve the developed strain rate dependent micromechanics model. The validities of these assumptions are investigated using numerical and theoretical approaches. A method to determine through the thickness strain and transverse Poisson's ratio of the composite is developed. The revised micromechanics model is then implemented into a higher order laminated plate theory which is modified to include the effects of inelastic strains. Parametric studies are conducted to investigate the mechanical response of composite plates under high strain rate loadings. Results show the transverse shear stresses cannot be neglected in the impact problem. A significant level of strain rate dependency and material nonlinearity is found in the deformation response of representative composite specimens.

  10. Theory of microphase separation on side-chain liquid-crystalline polymers with flexible spacers.

    PubMed

    Hernández-Jiménez, M; Westfahl, H

    2007-05-01

    We model a melt of monodisperse side-chain liquid-crystalline polymers as a melt of comb copolymers in which the side groups are rod-coil diblock copolymers. We consider both excluded-volume and Maier-Saupe interactions. The first acts among any pair of segments while the latter acts only between rods. Using a free-energy functional calculated from this microscopic model, we study the spinodal stability of the isotropic phase against density and orientational fluctuations. The phase diagram obtained in this way predicts nematic and smectic instabilities as well as the existence of microphases or phases with modulated wave vector but without nematic ordering. Such microphases are the result of the competition between the incompatibility among the blocks and the connectivity constraints imposed by the spacer and the backbone. Also the effects of the polymerization degree and structural conformation of the monomeric units on the phase behavior of the side-chain liquid-crystalline polymers are studied. PMID:17541501

  11. Computational conformational antimicrobial analysis developing mechanomolecular theory for polymer biomaterials in materials science and engineering

    NASA Astrophysics Data System (ADS)

    Petersen, Richard C.

    2014-03-01

    Single-bond rotations or pyramidal inversions tend to either hide or expose relative energies that exist for atoms with nonbonding lone-pair electrons. Availability of lone-pair electrons depends on overall molecular electron distributions and differences in the immediate polarity of the surrounding pico/nanoenvironment. Stereochemistry three-dimensional aspects of molecules provide insight into conformations through single-bond rotations with associated lone-pair electrons on oxygen atoms in addition to pyramidal inversions with nitrogen atoms. When electrons are protected, potential energy is sheltered toward an energy minimum value to compatibilize molecularly with nonpolar environments. When electrons are exposed, maximum energy is available toward polar environment interactions. Computational conformational analysis software calculated energy profiles that exist during specific oxygen ether single-bond rotations with easy-to-visualize three-dimensional models for the trichlorinated bisaromatic ether triclosan antimicrobial polymer additive. As shown, fluctuating alternating bond rotations can produce complex interactions between molecules to provide entanglement strength for polymer toughness or alternatively disrupt weak secondary bonds of attraction to lower resin viscosity for new additive properties with nonpolar triclosan as a hydrophobic toughening/wetting agent. Further, bond rotations involving lone-pair electrons by a molecule at a nonpolar-hydrocarbon-membrane/polar-biologic-fluid interface might become sufficiently unstable to provide free mechanomolecular energies to disrupt weaker microbial membranes, for membrane transport of molecules into cells, provide cell signaling/recognition/defense and also generate enzyme mixing to speed reactions.

  12. Computational conformational antimicrobial analysis developing mechanomolecular theory for polymer biomaterials in materials science and engineering

    PubMed Central

    Petersen, Richard C.

    2014-01-01

    Single-bond rotations or pyramidal inversions tend to either hide or expose relative energies that exist for atoms with nonbonding lone-pair electrons. Availability of lone-pair electrons depends on overall molecular electron distributions and differences in the immediate polarity of the surrounding pico/nanoenvironment. Stereochemistry three-dimensional aspects of molecules provide insight into conformations through single-bond rotations with associated lone-pair electrons on oxygen atoms in addition to pyramidal inversions with nitrogen atoms. When electrons are protected, potential energy is sheltered toward an energy minimum value to compatibilize molecularly with nonpolar environments. When electrons are exposed, maximum energy is available toward polar environment interactions. Computational conformational analysis software calculated energy profiles that exist during specific oxygen ether single-bond rotations with easy-to-visualize three-dimensional models for the trichlorinated bisaromatic ether triclosan antimicrobial polymer additive. As shown, fluctuating alternating bond rotations can produce complex interactions between molecules to provide entanglement strength for polymer toughness or alternatively disrupt weak secondary bonds of attraction to lower resin viscosity for new additive properties with nonpolar triclosan as a hydrophobic toughening/wetting agent. Further, bond rotations involving lone-pair electrons by a molecule at a nonpolar-hydrocarbon-membrane/polar-biologic-fluid interface might become sufficiently unstable to provide free mechanomolecular energies to disrupt weaker microbial membranes, for membrane transport of molecules into cells, provide cell signaling/recognition/defense and also generate enzyme mixing to speed reactions. PMID:25598972

  13. Theory of non-Condon emission from the interchain exciton in conjugated polymer aggregates

    NASA Astrophysics Data System (ADS)

    Bittner, Eric R.; Karabunarliev, Stoyan; Herz, Laura M.

    2007-05-01

    The authors present here a simple analysis that explains the apparent strengthening of electron phonon interaction upon aggregation in conjugated polymer materials. The overall scheme is that of an intermolecular Herzberg-Teller effect whereby sidebands of a forbidden transition are activated by oppositely phased vibrations. The authors show that upon aggregation, the 0-0 emission becomes symmetry forbidden and the apparent redshift and remaining vibronic structure are due to sideband (0-1,0-2, etc.) emission. At higher temperatures, the 0-0 peak is due to thermal population in a higher lying even-parity vibronic state rather than direct emission from the odd-paritied lowest intermolecular vibronic state.

  14. A statistical theory of coil-to-globule-to-coil transition of a polymer chain in a mixture of good solvents

    NASA Astrophysics Data System (ADS)

    Budkov, Yu. A.; Kolesnikov, A. L.; Kalikin, N. N.; Kiselev, M. G.

    2016-05-01

    We present an off-lattice statistical model of a single polymer chain in mixed-solvent media. Taking into account the polymer conformational entropy, renormalization of solvent composition near the polymer backbone, the universal intermolecular excluded-volume and van der Waals interactions within the self-consistent field theory, the reentrant coil-to-globule-to-coil transition (co-nonsolvency) has been described in this paper. For convenience we split the system volume in two parts: the volume occupied by the polymer chain and the volume of bulk solution. Considering the equilibrium between two sub-volumes, the polymer solvation free energy as a function of radius of gyration and co-solvent mole fraction within internal polymer volume has been obtained. Minimizing the free energy of solvation with respect to its arguments, we show two qulitatively different regimes of co-nonsolvency. Namely, at sufficiently high temperature the reentrant coil-to-globule-to-coil transition proceeds smoothly. On the contrary, when the temperature drops below a certain threshold value a coil-globule transition occurs in the regime of first-order phase transition, i.e., discontinuous changes of the radius of gyration and the local co-solvent mole fraction near the polymer backbone. We show that, when the collapse of the polymer chain takes place, the entropy and enthalpy contributions to the solvation free energy of the globule strongly grow. From the first principles of statistical thermodynamics we confirm earlier speculations based on the MD simulations results that the co-nonsolvency is the essentially enthalpic-entropic effect and is caused by enthalpy-entropy compensation. We show that the temperature dependences of the solution heat capacity change due to the solvation of the polymer chain are in qualitative agreement with the differential scanning calorimetry data for PNIPAM in aqueous methanol.

  15. Theory of Polymer Entrapped Enzyme Ultramicroelectrodes: Application to Glucose and Adenosine Triphosphate Detection

    PubMed Central

    Kottke, Peter A.; Kranz, Christine; Kwon, Yong Koo; Masson, Jean-Francois; Mizaikoff, Boris; Fedorov, Andrei G.

    2010-01-01

    We validate, by comparison with experimental data, a theoretical description of the amperometric response of microbiosensors formed via enzyme entrapment. The utility of the theory is further illustrated with two relevant examples supported by experiments: (1) quantitative detection of glucose and (2) quantitative detection of adenosine triphosphate (ATP). PMID:20445817

  16. Plasma-aided manufacturing

    NASA Astrophysics Data System (ADS)

    Shohet, J. L.

    1993-12-01

    Plasma-aided manufacturing is used for producing new materials with unusual and superior properties, for developing new chemical compounds and processes, for machining, and for altering and refining materials and surfaces. Plasma-aided manufacturing has direct applications to semiconductor fabrication, materials synthesis, welding, lighting, polymers, anti-corrosion coatings, machine tools, metallurgy, electrical and electronics devices, hazardous waste removal, high performance ceramics, and many other items in both the high-technology and the more traditional industries in the United States.

  17. A theory of electrophoresis of emulsion drops in aqueous two-phase polymer systems

    NASA Technical Reports Server (NTRS)

    Levine, S.

    1982-01-01

    An electrophoresis study has been carried out in an emulsion formed from an electrically neutral aqueous mixture of dextran and polyethylene glycol equilibrated at sufficient concentrations in the presence of electrolytes. Electrophoresis of a drop of one phase suspended in the other is observed, and the direction of the drop's motion is reversed when the disperse phase and the continuous phase are interchanged. In the presence of sulfate, phosphate, or citrate ions, an electrostatic potential difference of the order of a few mV exists between the two phases. The potential implied by the direction of the electrophoretic motion is opposite to the Donnan potential observed between the two phases. The mobility of an emulsion drop increases with the drop radius and depends on ion concentration. These results are explained in terms of a model postulating an electric dipole layer associated with a mixture of oriented polymer molecules at the surface of a drop, with a potential difference between the interiors of the two phases resulting from the unequal ion distribution.

  18. Polymer Fluid Dynamics.

    ERIC Educational Resources Information Center

    Bird, R. Byron

    1980-01-01

    Problems in polymer fluid dynamics are described, including development of constitutive equations, rheometry, kinetic theory, flow visualization, heat transfer studies, flows with phase change, two-phase flow, polymer unit operations, and drag reduction. (JN)

  19. Implementation of Higher Order Laminate Theory Into Strain Rate Dependent Micromechanics Analysis of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Kim, Heung Soo; Zhu, Linfa; Chattopadhyay, Aditi; Goldberg, Robert K.

    2004-01-01

    A procedure has been developed to investigate the nonlinear response of composite plates under large strain and high strain rate loading. A recently developed strain dependent micromechanics model is extended to account for the shear effects during impact. Four different assumptions of shear deformation effects are investigated to improve the development strain rate dependent micromechanics model. A method to determine through the thickness strain and transverse Poisson's ratio is developed. The revised micromechanics model is implemented into higher order laminate theory. Parametric studies are conducted to investigate transverse shear effects during impact.

  20. Co-non-solvency: Mean-field polymer theory does not describe polymer collapse transition in a mixture of two competing good solvents

    SciTech Connect

    Mukherji, Debashish; Stuehn, Torsten; Kremer, Kurt; Marques, Carlos M.

    2015-03-21

    Smart polymers are a modern class of polymeric materials that often exhibit unpredictable behavior in mixtures of solvents. One such phenomenon is co-non-solvency. Co-non-solvency occurs when two (perfectly) miscible and competing good solvents, for a given polymer, are mixed together. As a result, the same polymer collapses into a compact globule within intermediate mixing ratios. More interestingly, polymer collapses when the solvent quality remains good and even gets increasingly better by the addition of the better cosolvent. This is a puzzling phenomenon that is driven by strong local concentration fluctuations. Because of the discrete particle based nature of the interactions, Flory-Huggins type mean field arguments become unsuitable. In this work, we extend the analysis of the co-non-solvency effect presented earlier [D. Mukherji et al., Nat. Commun. 5, 4882 (2014)]. We explain why co-non-solvency is a generic phenomenon, which can only be understood by the thermodynamic treatment of the competitive displacement of (co)solvent components. This competition can result in a polymer collapse upon improvement of the solvent quality. Specific chemical details are not required to understand these complex conformational transitions. Therefore, a broad range of polymers are expected to exhibit similar reentrant coil-globule-coil transitions in competing good solvents.

  1. Theory of polymer-nanopore interactions refined using molecular dynamics simulations.

    PubMed

    Balijepalli, Arvind; Robertson, Joseph W F; Reiner, Joseph E; Kasianowicz, John J; Pastor, Richard W

    2013-05-01

    Molecular dynamics simulations were used to refine a theoretical model that describes the interaction of single polyethylene glycol (PEG) molecules with α-hemolysin (αHL) nanopores. The simulations support the underlying assumptions of the model, that PEG decreases the pore conductance by binding cations (which reduces the number of mobile ions in the pore) and by volume exclusion, and provide bounds for fits to new experimental data. Estimation of cation binding indicates that four monomers coordinate a single K(+) in a crown-ether-like structure, with, on average, 1.5 cations bound to a PEG 29-mer at a bulk electrolyte concentration of 4 M KCl. Additionally, PEG is more cylindrical and has a larger cross-section area in the pore than in solution, although its volume is similar. Two key experimental quantities of PEG are described by the model: the ratio of single channel current in the presence of PEG to that in the polymer's absence (blockade depth) and the mean residence time of PEG in the pore. The refined theoretical model is simultaneously fit to the experimentally determined current blockade depth and the mean residence times for PEGs with 15 to 45 monomers, at applied transmembrane potentials of -40 to -80 mV and for three electrolyte concentrations. The model estimates the free energy of the PEG-cation complexes to be -5.3 kBT. Finally the entropic penalty of confining PEG to the pore is found to be inversely proportional to the electrolyte concentration. PMID:23590258

  2. Analytical theory of finite-size effects in mechanical desorption of a polymer chain.

    PubMed

    Skvortsov, A M; Klushin, L I; Fleer, G J; Leermakers, F A M

    2010-02-14

    We discuss a unique system that allows exact analytical investigation of first- and second-order transitions with finite-size effects: mechanical desorption of an ideal lattice polymer chain grafted with one end to a solid substrate with a pulling force applied to the other end. We exploit the analogy with a continuum model and use accurate mapping between the parameters in continuum and lattice descriptions, which leads to a fully analytical partition function as a function of chain length, temperature (or adsorption strength), and pulling force. The adsorption-desorption phase diagram, which gives the critical force as a function of temperature, is nonmonotonic and gives rise to re-entrance. We analyze the chain length dependence of several chain properties (bound fraction, chain extension, and heat capacity) for different cross sections of the phase diagram. Close to the transition a single parameter (the product of the chain length N and the deviation from the transition point) describes all thermodynamic properties. We discuss finite-size effects at the second-order transition (adsorption without force) and at the first-order transition (mechanical desorption). The first-order transition has some unusual features: The heat capacity in the transition region increases anomalously with temperature as a power law, metastable states are completely absent, and instead of a bimodal distribution there is a flat region that becomes more pronounced with increasing chain length. The reason for this anomaly is the absence of an excess surface energy for the boundary between adsorbed and stretched coexisting phases (this boundary is one segment only): The two states strongly fluctuate in the transition point. The relation between mechanical desorption and mechanical unzipping of DNA is discussed. PMID:20151736

  3. Advances in the generalized entropy theory of glass-formation in polymer melts.

    PubMed

    Dudowicz, Jacek; Douglas, Jack F; Freed, Karl F

    2014-12-21

    The generalized entropy theory (GET) of polymeric glass-forming liquids is reformulated into a computationally simpler and more natural formalism than the original version of this theory. The new theoretical framework greatly facilitates establishing essential trends in the dependence of the segmental relaxation time τ, fragility, characteristic temperatures of glass-formation, etc., on the combined influences of monomer molecular structure, chain rigidity, and cohesive interaction strength. Special attention is placed on the estimating the parameters of the phenomenological Vogel-Fulcher-Tammann relations for describing segmental relaxation in diverse liquids in the low temperature range of glass-formation, Tg > T > Tc (or Tg < T < Tg + 100 K), where Tg and Tc are, respectively, the glass transition temperature and the crossover temperature separating the high and low temperature regimes of glass-formation. Finally, we discuss how the molecular energetic interaction parameters of the GET can be estimated from experimental data. Illustrative calculations are performed for the stiffness factor σ and the cohesive energy density u as a first step in this direction. PMID:25527959

  4. Advances in the generalized entropy theory of glass-formation in polymer melts

    NASA Astrophysics Data System (ADS)

    Dudowicz, Jacek; Douglas, Jack F.; Freed, Karl F.

    2014-12-01

    The generalized entropy theory (GET) of polymeric glass-forming liquids is reformulated into a computationally simpler and more natural formalism than the original version of this theory. The new theoretical framework greatly facilitates establishing essential trends in the dependence of the segmental relaxation time τ, fragility, characteristic temperatures of glass-formation, etc., on the combined influences of monomer molecular structure, chain rigidity, and cohesive interaction strength. Special attention is placed on the estimating the parameters of the phenomenological Vogel-Fulcher-Tammann relations for describing segmental relaxation in diverse liquids in the low temperature range of glass-formation, Tg > T > Tc (or Tg < T < Tg + 100 K), where Tg and Tc are, respectively, the glass transition temperature and the crossover temperature separating the high and low temperature regimes of glass-formation. Finally, we discuss how the molecular energetic interaction parameters of the GET can be estimated from experimental data. Illustrative calculations are performed for the stiffness factor σ and the cohesive energy density u as a first step in this direction.

  5. Statistical Continuum Theory for the Effective Conductivity of Fiber Filled Polymer Composites: Effect of Orientation Distribution and Aspect Ratio

    SciTech Connect

    Mikdam, Amed; Makradi, A.; Ahzi, Said; Garmestani, Hamid; Li, Dongsheng; Remond, Y.

    2010-03-01

    Effective conductivity of polymer composites, filled with conducting fibers such as carbon nanotubes, is studied using statistical continuum theory. The fiber orientation distribution in the matrix plays a very important role on their effective properties. To take into account their orientation, shape and distribution, two-point and three-point probability distribution functions are used. The effect of fibers orientation is illustrated by comparing the effective conductivity of microstructures with oriented and non-oriented fibers. The randomly oriented fibers result in an isotropic effective conductivity. The increased fiber orientation distribution can lead to higher anisotropy in conductivity. The effect of fiber’s aspect ratio on the effective conductivity is studied by comparing microstructures with varying degrees of fiber orientation distribution. Results show that the increase in anisotropy leads to higher conductivity in the maximum fiber orientation distribution direction and lower conductivity in the transverse direction. These results are in agreement with various models from the literature that show the increase of the aspect ratio of fibers improves the electrical and thermal conductivity.

  6. Density functional theory study of epoxy polymer chains adsorbing onto single-walled carbon nanotubes: electronic and mechanical properties.

    PubMed

    Ahangari, Morteza Ghorbanzadeh; Fereidoon, Abdolhosein; Ganji, Masoud Darvish

    2013-08-01

    We performed first principles calculations based on density functional theory (DFT) to investigate the effect of epoxy monomer content on the electronic and mechanical properties of single-walled carbon nanotubes (SWCNTs). Our calculation results reveal that interfacial interaction increases with increasing numbers of epoxy monomers on the surface of SWCNTs. Furthermore, density of states (DOS) results showed no orbital hybridization between the epoxy monomers and nanotubes. Mulliken charge analysis shows that the epoxy polymer carries a positive charge that is directly proportional to the number of monomers. The Young's modulus of the nanotubes was also studied as a function of monomer content. It was found that, with increasing number of monomers on the nanotubes, the Young's modulus first decreases and then approaches a constant value. The results of a SWCNT pullout simulation suggest that the interfacial shear stress of the epoxy/SWCNT complex is approximately 68 MPa. These results agreed well with experimental results, thus proving that the simulation methods used in this study are viable. PMID:23609226

  7. Morphology and Performance of Polymer Solar Cell Characterized by DPD Simulation and Graph Theory

    NASA Astrophysics Data System (ADS)

    Du, Chunmiao; Ji, Yujin; Xue, Junwei; Hou, Tingjun; Tang, Jianxin; Lee, Shuit-Tong; Li, Youyong

    2015-11-01

    The morphology of active layers in the bulk heterojunction (BHJ) solar cells is critical to the performance of organic photovoltaics (OPV). Currently, there is limited information for the morphology from transmission electron microscopy (TEM) techniques. Meanwhile, there are limited approaches to predict the morphology /efficiency of OPV. Here we use Dissipative Particle Dynamics (DPD) to determine 3D morphology of BHJ solar cells and show DPD to be an efficient approach to predict the 3D morphology. Based on the 3D morphology, we estimate the performance indicator of BHJ solar cells by using graph theory. Specifically, we study poly (3-hexylthiophene)/[6, 6]-phenyl-C61butyric acid methyl ester (P3HT/PCBM) BHJ solar cells. We find that, when the volume fraction of PCBM is in the region 0.4 ∼ 0.5, P3HT/PCBM will show bi-continuous morphology and optimum performance, consistent with experimental results. Further, the optimum temperature (413 K) for the morphology and performance of P3HT/PCBM is in accord with annealing results. We find that solvent additive plays a critical role in the desolvation process of P3HT/PCBM BHJ solar cell. Our approach provides a direct method to predict dynamic 3D morphology and performance indicator for BHJ solar cells.

  8. Morphology and Performance of Polymer Solar Cell Characterized by DPD Simulation and Graph Theory

    PubMed Central

    Du, Chunmiao; Ji, Yujin; Xue, Junwei; Hou, Tingjun; Tang, Jianxin; Lee, Shuit-Tong; Li, Youyong

    2015-01-01

    The morphology of active layers in the bulk heterojunction (BHJ) solar cells is critical to the performance of organic photovoltaics (OPV). Currently, there is limited information for the morphology from transmission electron microscopy (TEM) techniques. Meanwhile, there are limited approaches to predict the morphology /efficiency of OPV. Here we use Dissipative Particle Dynamics (DPD) to determine 3D morphology of BHJ solar cells and show DPD to be an efficient approach to predict the 3D morphology. Based on the 3D morphology, we estimate the performance indicator of BHJ solar cells by using graph theory. Specifically, we study poly (3-hexylthiophene)/[6, 6]-phenyl-C61butyric acid methyl ester (P3HT/PCBM) BHJ solar cells. We find that, when the volume fraction of PCBM is in the region 0.4 ∼ 0.5, P3HT/PCBM will show bi-continuous morphology and optimum performance, consistent with experimental results. Further, the optimum temperature (413 K) for the morphology and performance of P3HT/PCBM is in accord with annealing results. We find that solvent additive plays a critical role in the desolvation process of P3HT/PCBM BHJ solar cell. Our approach provides a direct method to predict dynamic 3D morphology and performance indicator for BHJ solar cells. PMID:26581407

  9. Morphology and Performance of Polymer Solar Cell Characterized by DPD Simulation and Graph Theory.

    PubMed

    Du, Chunmiao; Ji, Yujin; Xue, Junwei; Hou, Tingjun; Tang, Jianxin; Lee, Shuit-Tong; Li, Youyong

    2015-01-01

    The morphology of active layers in the bulk heterojunction (BHJ) solar cells is critical to the performance of organic photovoltaics (OPV). Currently, there is limited information for the morphology from transmission electron microscopy (TEM) techniques. Meanwhile, there are limited approaches to predict the morphology /efficiency of OPV. Here we use Dissipative Particle Dynamics (DPD) to determine 3D morphology of BHJ solar cells and show DPD to be an efficient approach to predict the 3D morphology. Based on the 3D morphology, we estimate the performance indicator of BHJ solar cells by using graph theory. Specifically, we study poly (3-hexylthiophene)/[6, 6]-phenyl-C61butyric acid methyl ester (P3HT/PCBM) BHJ solar cells. We find that, when the volume fraction of PCBM is in the region 0.4 ∼ 0.5, P3HT/PCBM will show bi-continuous morphology and optimum performance, consistent with experimental results. Further, the optimum temperature (413 K) for the morphology and performance of P3HT/PCBM is in accord with annealing results. We find that solvent additive plays a critical role in the desolvation process of P3HT/PCBM BHJ solar cell. Our approach provides a direct method to predict dynamic 3D morphology and performance indicator for BHJ solar cells. PMID:26581407

  10. Manufacturing Success

    ERIC Educational Resources Information Center

    Reese, Susan

    2007-01-01

    According to the National Association of Manufacturers (NAM), "manufacturing is the engine that drives American prosperity". When NAM and its research and education arm, The Manufacturing Institute, released the handbook, "The Facts About Modern Manufacturing," in October 2006, NAM President John Engler noted, that manufacturing output in America…

  11. Polymer concrete patching manual

    NASA Astrophysics Data System (ADS)

    Fontana, J. J.; Bartholomew, J.

    1982-06-01

    The practicality of using polymer concrete to repair deteriorated portland cement concrete bridge decks and pavements was demonstrated. This manual outlines the procedures for using polymer concrete as a rapid patching material to repair deteriorated concrete. The process technology, materials, equipment, and safety provisions used in manufacturing and placing polymer concrete are discussed. Potential users are informed of the various steps necessary to insure successful field applications of the material.

  12. Photovoltaic manufacturing technology monolithic amorphous silicon modules on continuous polymer substrates. Annual technical progress report, July 5, 1996--December 31, 1997

    SciTech Connect

    Jeffrey, F.

    1998-08-01

    Iowa Thin Film Technologies, Inc.`s (ITF) goal is to develop the most cost effective PV manufacturing process possible. To this end the authors have chosen a roll based manufacturing process with continuous deposition and monolithic integration. Work under this program is designed to meet this goal by improving manufacturing throughput and performance of the manufactured devices. Significant progress was made during Phase 2 of this program on a number of fronts. A new single pass tandem deposition machine was brought on line which allows greatly increased and improved throughput for rolls of tandem material. The TCO deposition process was improved resulting in an increase in throughput by 20%. A new alignment method was implemented on the printing process which improves throughput six fold while improving alignment from 100 {micro}m to 10 {micro}m. A roll based lamination procedure was developed and implemented on selected products which improves throughput from 20 sq. ft./hr. to 240 sq. ft./hr. A wide range of lower cost encapsulants were evaluated. A promising material was selected initially to be introduced in 5 year lifetime type products. The sum of these improvements bring the overall cost reduction resulting from this program to 49%.

  13. A new insight into the isotropic-nematic phase transition in lyotropic solutions of semiflexible polymers: density-functional theory tested by molecular dynamics.

    PubMed

    Egorov, Sergei A; Milchev, Andrey; Virnau, Peter; Binder, Kurt

    2016-06-14

    Semiflexible polymers in solution are studied for a wide range of both contour length L and persistence length lp as a function of monomer concentration under good solvent conditions. Both density-functional theory (DFT) and molecular dynamics (MD) simulation methods are used, and a very good agreement between both techniques is observed for rather stiff polymers. Evidence for a new mechanism of order parameter fluctuations in the nematic phase is presented, namely collective deformations of bundles of wormlike chains twisted around each other, and the typical wavelengths and amplitudes of these modes are estimated. These long wavelength fluctuations cause a reduction of the order parameter in comparison with the DFT prediction. It is also found that DFT becomes unreliable for rather flexible polymers in predicting that the transition from the isotropic (I)-phase to the nematic (N)-phase still exists at very high monomer concentrations (which in reality does not occur). However, under conditions when DFT is accurate, it provides reliable predictions also for the width of the I-N two-phase coexistence region, which are difficult to obtain from MD in spite of the use of very large systems (up to 500 000 monomers) by means of graphics processing units (GPU). For short and not very stiff chains, a pre-transitional chain stretching is found in the isotropic phase near the I-N-transition, not predicted by theories. A comparison with theoretical predictions by Khokhlov-Semenov, Odijk, and Chen reveals that the scaled transition densities are not simply functions of L/lp only, as these theories predict, but depend on d/lp (where d is the chain diameter) as well. Chain properties in the nematically ordered phase are compared to those of chains confined in tubes, and the deflection length concept is tested. Eventually, some consequences for the interpretation of experiments are spelled out. PMID:27249320

  14. Functional polymers

    SciTech Connect

    Wegner, G.

    2000-01-01

    Improving the existing polymer materials and the designing of model polymers need fundamental insights into the structure and dynamics over a large range of length and time scales. Consequently, a host of quite different methods needs to be applied to gain insights into the molecular and supramolecular structures and interactions that determine the performance of these materials. Supramolecular structures derived from shape persistent (stiff) macromolecules are used as examples to demonstrate the correlation between chemical structure, order phenomena and performance in applications concerning advanced or developing technologies: organic light emitting diodes (OLEDs) and separator membranes in lithium based batteries and fuel cells. Polymers are also important as additives in the manufacture and the processing of other materials. The design of block copolymers to control the nucleation and growth of inorganic particles precipitating from aqueous solutions (mineralization) is discussed as well as the use of block copolymers to optimize the processing of ceramic pieces and objects. Finally, the modification of surfaces by polymers including aspects of biocompatibility is discussed. Some remarks concerning the importance of recent developments and advances in synthesis of macromolecular materials are also given.

  15. Ketoprofen-poly(D,L-lactic-co-glycolic acid) microspheres: influence of manufacturing parameters and type of polymer on the release characteristics.

    PubMed

    Gabor, F; Ertl, B; Wirth, M; Mallinger, R

    1999-01-01

    The effect of manufacturing parameters on the size and drug-loading of ketoprofen-containing biodegradable and biocompatible poly(DL-lactic-co-glycolic acid) (PLGA) microspheres prepared by the solvent evaporation method was investigated. For both drug-free and drug-loaded microspheres, smaller microspheres with a narrower size distribution were obtained when the stirring rate or the volume of the organic phase was increased. Incorporation of ketoprofen was found to increase with increasing volume of the organic phase and decreasing pH of the aqueous phase, but was independent of the acidity and the inherent viscosity of the PLGA used. The biphasic release profile of ketoprofen from the microspheres was dependent on the type of PLGA as well as the size and drug-loading, two parameters governed by the manufacturing process. The first burst effect was found to increase with the drug content, reduction of size of the microspheres and increasing inherent viscosity of the matrix, whereas acidity of the PLGA had no effect on the release of this acidic drug. A vigorous first burst effect was associated with reduced sustained delivery of ketoprofen, the rate of the delayed release phase being dependent on the inherent viscosity of the matrix, the size, the payload and the pH during preparation of the microspheres. Thus, by selection of the manufacturing parameters and the type of PLGA, it is possible to design a controlled drug delivery system for the prolonged release of ketoprofen, improving therapy by possible reduction of time intervals between peroral administration and reduction of local gastrointestinal side effects. PMID:9972498

  16. Polymer Functionalized Nanoparticles in Polymer Nanocomposites

    NASA Astrophysics Data System (ADS)

    Jayaraman, Arthi

    2013-03-01

    Significant interest has grown around the ability to control spatial arrangement of nanoparticles in a polymer nanocomposite to engineer materials with target properties. Past work has shown that one could achieve controlled assembly of nanoparticles in the polymer matrix by functionalizing nanoparticle surfaces with homopolymers. This talk will focus on our recent work using Polymer Reference Interaction Site Model (PRISM) theory and Monte Carlo simulations and GPU-based molecular dynamics simulations to specifically understand how heterogeneity in the polymer functionalization in the form of a) copolymers with varying monomer chemistry and monomer sequence, and b) polydispersity in homopolymer grafts can tune effective interactions between functionalized nanoparticles, and the assembly of functionalized nanoparticles.

  17. Photovoltaic manufacturing technology monolithic amorphous silicon modules on continuous polymer substrates. Annual technical progress report, 5 July 1995--4 June 1996

    SciTech Connect

    Jeffrey, F

    1997-02-01

    Iowa Thin Film Technologies` goal is to develop the most cost-effective photovoltaic manufacturing process possible. During the first year, they developed the capability of sputtering a high-quality (Zn(Al)O) successfully implemented increased deposition rates for the ZnO top contact deposition; improved registration and ink-line width to reduce area loss due to interconnects; developed a new alignment process and sensor to improve the speed and accuracy of registration for the patterning processes; developed a new Silver ink composition that allows finer print lines and lower series resistance; demonstrated an 8% overall improvement in area utilization; evaluated water-based insulator inks for compatibility with their processes; investigated and tested the use of roll-based lamination as a means to reduce the cost of assembly; developed straight roll lamination capability using pressure-sensitive adhesives and thermally activated bonding; and evaluated the use of the standard EVA/Tefzel encapsulant with a roll laminator.

  18. Task 1: Modeling Study of CO Effects on Polymer Electrolyte Fuel Cell Anodes Task 2: Study of Ac Impedance as Membrane/Electrode Manufacturing Diagnostic Tool

    SciTech Connect

    Thomas E. Springer

    1998-01-30

    Carbon monoxide poisoning of polymer electrolyte fuel cell anodes is a key problem to be overcome when operating a polymer electrolyte fuel cell (PEFC) on reformed fuels. CO adsorbs preferentially on the precious metal surface leading to substantial performance losses. Some recent work has explored this problem, primarily using various Pt alloys in attempts to lower the degree of surface deactivation. In their studies of hydrogen oxidation on Pt and Pt alloy (Pt/Sn, Pt/Ru) rotating disk electrodes exposed to H{sub 2}/CO mixtures, Gasteiger et al. showed that a small hydrogen oxidation current is observed well before the onset of major CO oxidative stripping (ca. 0.4 V) on Pt/Ru. However, these workers concluded that such current observed at low anode overpotentials was too low to be of practical value. Nonetheless, MST-11 researchers and others have found experimentally that it is possible to run a PEFC, e.g., with a Pt/Ru anode, in the presence of CO levels in the range 10--100 ppm with little voltage loss. Such experimental results suggest that, in fact, PEFC operation at significant current densities under low anode overpotentials is possible in the presence of such levels of CO, even before resorting to air bleeding into the anode feed stream. The latter approach has been shown to be effective in elimination of Pt anode catalyst poisoning effects at CO levels of 20--50 ppm for cells operating at 80 C with low Pt catalyst loading. The effect of oxygen bleeding is basically to lower P{sub CO} down to extremely low levels in the anode plenum thanks to the catalytic (chemical) oxidation of CO by dioxygen at the anode catalyst. In this modeling work the authors do not include specific description of oxygen bleeding effects and concentrate on the behavior of the anode with feed streams of H{sub 2} or reformate containing low levels of CO. The anode loss is treated in this work as a hydrogen and carbon monoxide electrode kinetics problem, but includes the effects of

  19. Assumption of separability of the excluded-volume interaction in polymer physics: Flory-Huggins theory reviewed

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Somendra M.

    1986-08-01

    Rotational isomerism and the excluded-volume interaction are generally considered to be the two major factors in polymer crystallization, glass transition, etc. The calculations supporting this belief are based on the assumption that the contribution to the free energy from the excluded-volume interaction is separable from the rest of the interactions. This separability assumption is studied here by mapping a single-polymer-chain problem to a spin problem with a cluster interaction. Using a variational principle, which provides an upper bound to the free energy, it is shown that the separability assumption gives a qualitatively incorrect description of the system in the low-temperature region. The consequences of this result for general models are also discussed.

  20. Thermodynamics of polymer nematics described with a worm-like chain model: particle-based simulations and SCF theory calculations

    NASA Astrophysics Data System (ADS)

    Greco, Cristina; Yiang, Ying; Kremer, Kurt; Chen, Jeff; Daoulas, Kostas

    Polymer liquid crystals, apart from traditional applications as high strength materials, are important for new technologies, e.g. Organic Electronics. Their studies often invoke mesoscale models, parameterized to reproduce thermodynamic properties of the real material. Such top-down strategies require advanced simulation techniques, predicting accurately the thermodynamics of mesoscale models as a function of characteristic features and parameters. Here a recently developed model describing nematic polymers as worm-like chains interacting with soft directional potentials is considered. We present a special thermodynamic integration scheme delivering free energies in particle-based Monte Carlo simulations of this model, avoiding thermodynamic singularities. Conformational and structural properties, as well as Helmholtz free energies are reported as a function of interaction strength. They are compared with state-of-art SCF calculations invoking a continuum analog of the same model, demonstrating the role of liquid-packing and fluctuations.

  1. Energy-level alignment and open-circuit voltage at graphene/polymer interfaces: theory and experiment

    NASA Astrophysics Data System (ADS)

    Noori, Keian; Konios, Dimitrios; Stylianakis, Minas M.; Kymakis, Emmanuel; Giustino, Feliciano

    2016-03-01

    Functionalized graphene promises to become a key component of novel solar cell architectures, owing to its versatile ability to act either as transparent conductor, electron acceptor, or buffer layer. In spite of this promise, the solar energy conversion efficiency of graphene-based devices falls short of the performance of competing solution-processable photovoltaic technologies. Here we address the question of the maximum achievable open-circuit voltage of all-organic graphene: polymer solar cells using a combined theoretical/experimental approach, going from the atomic scale level to the device level. Our calculations on very large atomistic models of the graphene/polymer interface indicate that the ideal open-circuit voltage approaches one volt, and that epoxide functional groups can have a dramatic effect on the photovoltage. Our predictions are confirmed by direct measurements on complete devices where we control the concentration of functional groups via chemical reduction. Our findings indicate that the selective removal of epoxide groups and the use of ultradisperse polymers are key to achieving graphene solar cells with improved energy conversion efficiency.

  2. Cable manufacture

    NASA Technical Reports Server (NTRS)

    Gamble, P.

    1972-01-01

    A survey is presented of flat electrical cable manufacturing, with particular reference to patented processes. The economics of manufacture based on an analysis of material and operating costs is considered for the various methods. Attention is given to the competitive advantages of the several processes and their resulting products. The historical area of flat cable manufacture is presented to give a frame of reference for the survey.

  3. Manufacturing technologies

    SciTech Connect

    1995-09-01

    The Manufacturing Technologies Center is an integral part of Sandia National Laboratories, a multiprogram engineering and science laboratory, operated for the Department of Energy (DOE) with major facilities at Albuquerque, New Mexico, and Livermore, California. Our Center is at the core of Sandia`s Advanced Manufacturing effort which spans the entire product realization process.

  4. Manufacturing Technology.

    ERIC Educational Resources Information Center

    Barnes, James L.

    This curriculum guide is designed to assist junior high school industrial arts teachers in planning new courses and revising existing courses in manufacturing technology. Addressed in the individual units of the guide are the following topics: introduction to manufacturing, materials processing, personnel management, production management,…

  5. On the origin of Gaussian network theory in the thermo/chemo-responsive shape memory effect of amorphous polymers undergoing photo-elastic transition

    NASA Astrophysics Data System (ADS)

    Lu, Haibao; Huang, Wei Min; Leng, Jinsong

    2016-06-01

    Amorphous polymers are normally isotropic in their physical properties, however, upon stress their structural randomness is disturbed and they become anisotropic. There is a close connection between the optical anisotropy and the elastic (or mechanical) anisotropy, since both are related to the type of symmetry exhibited by the molecular structure. On the origin of Gaussian network theory, a phenomenological constitutive framework was proposed to study the photo-elastic transition and working mechanism of the thermo-/chemo-responsive shape-memory effect (SME) in amorphous shape memory polymers (SMPs). Optically refractive index was initially employed to couple the stress, strain and the anisotropy of the random link in macromolecule chain. Based on the Arrhenius law, a constitutive framework was then applied for the temperature dependence of optical (or elastic or mechanical) anisotropy according to the fictive temperature parameter. Finally, the phenomenological photo-elastic model was proposed to quantitatively identify the influential factors behind the thermo-/chemo-responsive SME in SMPs, of which the shape recovery behavior is predicted and verified by the available experimental data reported in the literature.

  6. Viscoelastic Properties of Polymer Blends

    NASA Technical Reports Server (NTRS)

    Hong, S. D.; Moacanin, J.; Soong, D.

    1982-01-01

    Viscosity, shear modulus and other viscoelastic properties of multicomponent polymer blends are predicted from behavior of individual components, using a mathematical model. Model is extension of two-component-blend model based on Rouse-Bueche-Zimm theory of polymer viscoelasticity. Extension assumes that probabilities of forming various possible intracomponent and intercomponent entanglements among polymer molecules are proportional to relative abundances of components.

  7. Polymer films

    DOEpatents

    Granick, Steve; Sukhishvili, Svetlana A.

    2004-05-25

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  8. Polymer films

    DOEpatents

    Granick, Steve; Sukhishvili, Svetlana A.

    2008-12-30

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  9. Manufacturing technology

    SciTech Connect

    Blaedel, K.L.

    1997-02-01

    The specific goals of the Manufacturing Technology thrust area are to develop an understanding of fundamental fabrication processes, to construct general purpose process models that will have wide applicability, to document our findings and models in journals, to transfer technology to LLNL programs, industry, and colleagues, and to develop continuing relationships with industrial and academic communities to advance our collective understanding of fabrication processes. Advances in four projects are described here, namely Design of a Precision Saw for Manufacturing, Deposition of Boron Nitride Films via PVD, Manufacturing and Coating by Kinetic Energy Metallization, and Magnet Design and Application.

  10. Antioxidant Stabilisation of Polymers

    NASA Astrophysics Data System (ADS)

    Shlyapnikov, Yurii A.

    1981-06-01

    Physicochemical aspects of the stabilisation of polymers are discussed. Attention is paid mainly to the aging and stabilisation of polymers under processing conditions. Topics considered are the kinetics and mechanism of the high-temperature oxidation of polymers, critical phenomena in the inhibited oxidation of polymers, the theory of synergism and antagonism among antioxidants, the reasons for differences in efficiency of antioxidants, and certain aspects of the relation between the efficiency of antioxidants and their molecular structure. A list of 132 references is included.

  11. Manufacturing Laboratory (Fact Sheet)

    SciTech Connect

    Not Available

    2011-10-01

    This fact sheet describes the purpose, lab specifications, applications scenarios, and information on how to partner with NREL's Manufacturing Laboratory at the Energy Systems Integration Facility. The Manufacturing Laboratory at NREL's Energy Systems Integration Facility (ESIF) focuses on developing methods and technologies that will assist manufacturers of hydrogen and fuel cell technologies, as well as other renewable energy technologies, to scale up their manufacturing capabilities to volumes that meet DOE and industry targets. Specifically, the manufacturing activity is currently focused on developing and validating quality control techniques to assist manufacturers of low temperature and high temperature fuel cells in the transition from low to high volume production methods for cells and stacks. Capabilities include initial proof-of-concept studies through prototype system development and in-line validation. Existing diagnostic capabilities address a wide range of materials, including polymer films, carbon and catalyst coatings, carbon fiber papers and wovens, and multi-layer assemblies of these materials, as well as ceramic-based materials in pre- or post-fired forms. Work leading to the development of non-contact, non-destructive techniques to measure critical dimensional and functional properties of fuel cell and other materials, and validation of those techniques on the continuous processing line. This work will be supported by materials provided by our partners. Looking forward, the equipment in the laboratory is set up to be modified and extended to provide processing capabilities such as coating, casting, and deposition of functional layers, as well as associated processes such as drying or curing. In addition, continuous processes are used for components of organic and thin film photovoltaics (PV) as well as battery technologies, so synergies with these important areas will be explored.

  12. Smart Manufacturing.

    PubMed

    Davis, Jim; Edgar, Thomas; Graybill, Robert; Korambath, Prakashan; Schott, Brian; Swink, Denise; Wang, Jianwu; Wetzel, Jim

    2015-01-01

    Historic manufacturing enterprises based on vertically optimized companies, practices, market share, and competitiveness are giving way to enterprises that are responsive across an entire value chain to demand dynamic markets and customized product value adds; increased expectations for environmental sustainability, reduced energy usage, and zero incidents; and faster technology and product adoption. Agile innovation and manufacturing combined with radically increased productivity become engines for competitiveness and reinvestment, not simply for decreased cost. A focus on agility, productivity, energy, and environmental sustainability produces opportunities that are far beyond reducing market volatility. Agility directly impacts innovation, time-to-market, and faster, broader exploration of the trade space. These changes, the forces driving them, and new network-based information technologies offering unprecedented insights and analysis are motivating the advent of smart manufacturing and new information technology infrastructure for manufacturing. PMID:25898070

  13. Coil-bridge transition in a single polymer chain as an unconventional phase transition: Theory and simulation

    NASA Astrophysics Data System (ADS)

    Klushin, Leonid I.; Skvortsov, Alexander M.; Polotsky, Alexey A.; Hsu, Hsiao-Ping; Binder, Kurt

    2014-05-01

    The coil-bridge transition in a self-avoiding lattice chain with one end fixed at height H above the attractive planar surface is investigated by theory and Monte Carlo simulation. We focus on the details of the first-order phase transition between the coil state at large height H ⩾ Htr and a bridge state at H ⩽ Htr, where Htr corresponds to the coil-bridge transition point. The equilibrium properties of the chain were calculated using the Monte Carlo pruned-enriched Rosenbluth method in the moderate adsorption regime at (H/Na)tr ⩽ 0.27 where N is the number of monomer units of linear size a. An analytical theory of the coil-bridge transition for lattice chains with excluded volume interactions is presented in this regime. The theory provides an excellent quantitative description of numerical results at all heights, 10 ⩽ H/a ⩽ 320 and all chain lengths 40 < N < 2560 without free fitting parameters. A simple theory taking into account the effect of finite extensibility of the lattice chain in the strong adsorption regime at (H/Na)tr ⩾ 0.5 is presented. We discuss some unconventional properties of the coil-bridge transition: the absence of phase coexistence, two micro-phases involved in the bridge state, and abnormal behavior in the microcanonical ensemble.

  14. Coil-bridge transition in a single polymer chain as an unconventional phase transition: theory and simulation.

    PubMed

    Klushin, Leonid I; Skvortsov, Alexander M; Polotsky, Alexey A; Hsu, Hsiao-Ping; Binder, Kurt

    2014-05-28

    The coil-bridge transition in a self-avoiding lattice chain with one end fixed at height H above the attractive planar surface is investigated by theory and Monte Carlo simulation. We focus on the details of the first-order phase transition between the coil state at large height H ⩾ Htr and a bridge state at H ⩽ Htr, where Htr corresponds to the coil-bridge transition point. The equilibrium properties of the chain were calculated using the Monte Carlo pruned-enriched Rosenbluth method in the moderate adsorption regime at (H/Na)tr ⩽ 0.27 where N is the number of monomer units of linear size a. An analytical theory of the coil-bridge transition for lattice chains with excluded volume interactions is presented in this regime. The theory provides an excellent quantitative description of numerical results at all heights, 10 ⩽ H/a ⩽ 320 and all chain lengths 40 < N < 2560 without free fitting parameters. A simple theory taking into account the effect of finite extensibility of the lattice chain in the strong adsorption regime at (H/Na)tr ⩾ 0.5 is presented. We discuss some unconventional properties of the coil-bridge transition: the absence of phase coexistence, two micro-phases involved in the bridge state, and abnormal behavior in the microcanonical ensemble. PMID:24880326

  15. Polymer infiltration studies

    NASA Technical Reports Server (NTRS)

    Marchello, Joseph M.

    1992-01-01

    The preparation is reported of carbon fiber composites using advanced polymer resins. Current and ongoing research activities include: powder towpreg process; weaving, braiding and stitching dry powder prepreg; advanced tow placement; and customized ATP towpreg. The goal of these studies is to produce advanced composite materials for automated part fabrication using textile and robotics technology in the manufacture of subsonic and supersonic aircraft.

  16. Microgravity Manufacturing Via Fused Deposition

    NASA Technical Reports Server (NTRS)

    Cooper, K. G.; Griffin, M. R.

    2003-01-01

    Manufacturing polymer hardware during space flight is currently outside the state of the art. A process called fused deposition modeling (FDM) can make this approach a reality by producing net-shaped components of polymer materials directly from a CAE model. FDM is a rapid prototyping process developed by Stratasys, Inc.. which deposits a fine line of semi-molten polymer onto a substrate while moving via computer control to form the cross-sectional shape of the part it is building. The build platen is then lowered and the process is repeated, building a component directly layer by layer. This method enables direct net-shaped production of polymer components directly from a computer file. The layered manufacturing process allows for the manufacture of complex shapes and internal cavities otherwise impossible to machine. This task demonstrated the benefits of the FDM technique to quickly and inexpensively produce replacement components or repair broken hardware in a Space Shuttle or Space Station environment. The intent of the task was to develop and fabricate an FDM system that was lightweight, compact, and required minimum power consumption to fabricate ABS plastic hardware in microgravity. The final product of the shortened task turned out to be a ground-based breadboard device, demonstrating miniaturization capability of the system.

  17. Local know model of entangled polymer chains. 2. Theory of probe fluctuation and diffusion coefficient of a single local knot

    SciTech Connect

    Iwata, Kazuyoshi

    1992-05-14

    The local knot (LK) theory is tested by computer simulations in parts 1 and 2. Here, theoretical problems of the simulations are mainly discussed. The probe fluctuation found in part 1 is studied theoretically, and a method for separating the Markov motion of a LK from its probe fluctuation is proposed. A detailed discussions on the mechanism of the probe fluctuation and the uncertainty principal are given. A modified expression of the diffusion coefficient of a LK is derived that cancels the interference of the probe fluctuations, and its numerical calculation is performed. A correction for short memory effects of LK motion is also done. The theoretical value of d{sub 0} thus computed is 0.0393 bond{sup 2}/u.t. (u.t. - unit time) which is comparable to its simulation value 0.0172 bond{sup 2}/u.t. obtained in part 1. Finally, it is concluded that the LK theory is proved by the results of parts 1 and 2 and, by this, a true molecular theory of entanglement has been first established. 13 refs., 7 figs., 1 tab.

  18. Density Functional Theory of Simple Polymers in a Slit Pore: 2. The Role of Compressibility and Field Type

    SciTech Connect

    CURRO,JOHN G.; HOOPER,JUSTIN B.; MCCOY,JOHN D.; PILEGGI, MORGAN T.; WEINHOLD,JEFFREY D.

    1999-10-28

    Simple tangent, hard site chains near a hard wall are modeled with a Density Functional (DF) theory that uses the direct correlation function, c(r), as its ''input''. Two aspects of this DF theory are focused upon: (1) the consequences of variations in c(r)'s detailed form; and (2) the correct way to introduce c(r) into the DF formalism. The most important aspect of c(r) is found to be its integrated value, {cflx c}(0). Indeed, it appears that, for fixed {cflx c}(0), all reasonable guesses of the detailed shape of c(r) result in surprisingly similar density distributions, {rho}(r). Of course, the more accurate the c(r), the better the {rho}(r). As long as the length scale introduced by c(r) is roughly the hard site diameter and as long as the solution remains liquid-like, the {rho}(r) is found to be in good agreement with simulation results. The c(r) is used in DF theory to calculate the medium-induced-potential, U{sub M}(r) from the density distribution, {rho}(r). The form of U{sub M}(r) can be chosen to be one of a number of different forms. It is found that the forms for U{sub M}(r), which yield the most accurate results for the wall problem, are also those which were suggested as accurate in previous, related studies.

  19. Understanding Local and Macroscopic Electron Mobilities in the Fullerene Network of Conjugated Polymer-based Solar Cells. Time-Resolved Microwave Conductivity and Theory

    SciTech Connect

    Aguirre, Jordan C.; Arntsen, Christopher D.; Hernandez, Samuel; Huber, Rachel; Nardes, Alexandre M.; Halim, Merissa; Kilbride, Daniel; Rubin, Yves; Tolbert, Sarah H.; Kopidakis, Nikos; Schwartz, Benjamin J.; Neuhauser, Daniel

    2013-09-23

    The efficiency of bulk heterojunction (BHJ) organic photovoltaics is sensitive to the morphology of the fullerene network that transports electrons through the device. This sensitivity makes it difficult to distinguish the contrasting roles of local electron mobility (how easily electrons can transfer between neighboring fullerene molecules) and macroscopic electron mobility (how well-connected is the fullerene network on device length scales) in solar cell performance. In this work, a combination of density functional theory (DFT) calculations, flash-photolysis time-resolved microwave conductivity (TRMC) experiments, and space-charge-limit current (SCLC) mobility estimates are used to examine the roles of local and macroscopic electron mobility in conjugated polymer/fullerene BHJ photovoltaics. The local mobility of different pentaaryl fullerene derivatives (so-called ‘shuttlecock’ molecules) is similar, so that differences in solar cell efficiency and SCLC mobilities result directly from the different propensities of these molecules to self-assemble on macroscopic length scales. These experiments and calculations also demonstrate that the local mobility of phenyl-C60 butyl methyl ester (PCBM) is an order of magnitude higher than that of other fullerene derivatives, explaining why PCBM has been the acceptor of choice for conjugated polymer BHJ devices even though it does not form an optimal macroscopic network. The DFT calculations indicate that PCBM's superior local mobility comes from the near-spherical nature of its molecular orbitals, which allow strong electronic coupling between adjacent molecules. In combination, DFT and TRMC techniques provide a tool for screening new fullerene derivatives for good local mobility when designing new molecules that can improve on the macroscopic electron mobility offered by PCBM.

  20. Microgravity Manufacturing

    NASA Technical Reports Server (NTRS)

    Cooper, Ken; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    Manufacturing capability in outer space remains one of the critical milestones to surpass to allow humans to conduct long-duration manned space exploration. The high cost-to-orbit for leaving the Earth's gravitational field continues to be the limiting factor in carrying sufficient hardware to maintain extended life support in microgravity or on other planets. Additive manufacturing techniques, or 'chipless' fabrication, like RP are being considered as the most promising technologies for achieving in situ or remote processing of hardware components, as well as for the repair of existing hardware. At least three RP technologies are currently being explored for use in microgravity and extraterrestrial fabrication.

  1. The Economics of Big Area Addtiive Manufacturing

    SciTech Connect

    Post, Brian; Lloyd, Peter D; Lindahl, John; Lind, Randall F; Love, Lonnie J; Kunc, Vlastimil

    2016-01-01

    Case studies on the economics of Additive Manufacturing (AM) suggest that processing time is the dominant cost in manufacturing. Most additive processes have similar performance metrics: small part sizes, low production rates and expensive feedstocks. Big Area Additive Manufacturing is based on transitioning polymer extrusion technology from a wire to a pellet feedstock. Utilizing pellets significantly increases deposition speed and lowers material cost by utilizing low cost injection molding feedstock. The use of carbon fiber reinforced polymers eliminates the need for a heated chamber, significantly reducing machine power requirements and size constraints. We hypothesize that the increase in productivity coupled with decrease in feedstock and energy costs will enable AM to become more competitive with conventional manufacturing processes for many applications. As a test case, we compare the cost of using traditional fused deposition modeling (FDM) with BAAM for additively manufacturing composite tooling.

  2. Polymer Thermoelectric Generators: Device Considerations

    NASA Astrophysics Data System (ADS)

    Yee, Shannon

    2014-03-01

    Recent control of the transport properties in polymers has encouraged the development of polymer thermoelectric (TE) devices. Polymer TEs are thought to be less expensive and more scalable than their inorganic counterparts. The cost of the raw material is less and polymer TEs can leverage the large areal manufacturing technique established by the plastics industry. Additionally, while the overall ZT of polymer TEs appears attractive, individual polymer properties have a very different scale than their inorganic counterparts (i.e., the thermal conductivity and electrical conductivity are approximately one and two orders of magnitude smaller, respectively). Furthermore, the majority of TE measurements on polymers have been limited to thin-films where traditional TE materials are measured in bulk. So why should it be expected that polymer TE devices resemble traditional TE devices? Given the uniqueness of polymers, different device architectures are proposed that can leverage the unique strengths of polymer films. It will be shown that by logically considering device requirements, new polymer TE devices have non-linear features that are more attractive than linear inorganic TE devices. This leads to very different device optimizations that favor polymer TEs.

  3. Advancing manufacturing through computational chemistry

    SciTech Connect

    Noid, D.W.; Sumpter, B.G.; Tuzun, R.E.

    1995-12-31

    The capabilities of nanotechnology and computational chemistry are reaching a point of convergence. New computer hardware and novel computational methods have created opportunities to test proposed nanometer-scale devices, investigate molecular manufacturing and model and predict properties of new materials. Experimental methods are also beginning to provide new capabilities that make the possibility of manufacturing various devices with atomic precision tangible. In this paper, we will discuss some of the novel computational methods we have used in molecular dynamics simulations of polymer processes, neural network predictions of new materials, and simulations of proposed nano-bearings and fluid dynamics in nano- sized devices.

  4. Density functional theory investigation of opto-electronic properties of thieno[3,4-b]thiophene and benzodithiophene polymer and derivatives and their applications in solar cell.

    PubMed

    Khoshkholgh, Mehri Javan; Marsusi, Farah; Abolhassani, Mohammad Reza

    2015-02-01

    PTBs polymers with thieno[3,4-b]thiophene [TT] and benzodithiophene [BDT] units have particular properties, which demonstrate it as one of the best group of donor materials in organic solar cells. In the present work, density functional theory (DFT) is applied to investigate the optimized structure, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), band gap and dihedral angle of PTB7 at B3LYP/6-31G(d). Two different approaches are applied to carry out these investigations: Oligomer extrapolation technique and periodic boundary condition (PBC) method. The results obtained from PBC-DFT method are in fair agreement with experiments. Based on these reliable outcomes; the investigations continued to perform some derivatives of PTB7. In this study, sulfur is substituted by nitrogen, oxygen, silicon, phosphor or selenium atoms in pristine PTB7. Due to the shift of HOMO and LUMO levels, smaller band gaps are predicted to appear in some derivatives in comparison with PTB7. Maximum theoretical efficiencies, η, of the mentioned derivatives as well as local difference of dipole moments between the ground and excited states (Δμge) are computed. The results indicate that substitution of sulfur by nitrogen or oxygen in BDT unit, and silicon or phosphor in TT unit of pristine PTB7 leads to a higher η as well as Δμge. PMID:25311524

  5. Apparel Manufacture

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Marshall Space Flight Center teamed with the University of Alabama in Huntsville (UAH) in 1989 on a program involving development of advanced simulation software. Concurrently, the State of Alabama chartered UAH to conduct a technology advancement program in support of the state's apparel manufacturers. In 1992, under contract to Marshall, UAH developed an apparel-specific software package that allows manufacturers to design and analyze modules without making an actual investment -- it functions on ordinary PC equipment. By 1995, Marshall had responded to requests for the package from more than 400 companies in 36 states; some of which reported savings up to $2 million. The National Garment Company of Missouri, for example, uses the system to design and balance a modular line before committing to expensive hardware; for setting up sewing lines; and for determining the composition of a new team.

  6. Manufacturing technology

    SciTech Connect

    Leonard, J.A.; Floyd, H.L.; Goetsch, B.; Doran, L.

    1993-08-01

    This bulletin depicts current research on manufacturing technology at Sandia laboratories. An automated, adaptive process removes grit overspray from jet engine turbine blades. Advanced electronic ceramics are chemically prepared from solution for use in high- voltage varistors. Selective laser sintering automates wax casting pattern fabrication. Numerical modeling improves performance of photoresist stripper (simulation on Cray supercomputer reveals path to uniform plasma). And mathematical models help make dream of low- cost ceramic composites come true.

  7. Green Manufacturing

    SciTech Connect

    Patten, John

    2013-12-31

    Green Manufacturing Initiative (GMI): The initiative provides a conduit between the university and industry to facilitate cooperative research programs of mutual interest to support green (sustainable) goals and efforts. In addition to the operational savings that greener practices can bring, emerging market demands and governmental regulations are making the move to sustainable manufacturing a necessity for success. The funding supports collaborative activities among universities such as the University of Michigan, Michigan State University and Purdue University and among 40 companies to enhance economic and workforce development and provide the potential of technology transfer. WMU participants in the GMI activities included 20 faculty, over 25 students and many staff from across the College of Engineering and Applied Sciences; the College of Arts and Sciences' departments of Chemistry, Physics, Biology and Geology; the College of Business; the Environmental Research Institute; and the Environmental Studies Program. Many outside organizations also contribute to the GMI's success, including Southwest Michigan First; The Right Place of Grand Rapids, MI; Michigan Department of Environmental Quality; the Michigan Department of Energy, Labor and Economic Growth; and the Michigan Manufacturers Technical Center.

  8. Interpenetrations in polymer brushes

    NASA Astrophysics Data System (ADS)

    Chakrabarti, Amitabha; Nelson, Peter; Toral, Raúl

    1994-01-01

    We carry out Monte Carlo simulations in both lattice and off-lattice geometry, to study the configurational properties of a system of two polymer-coated plates. We compare our results with numerical and analytical self-consistent-field theories. For the short chain-lengths considered here, we find both compression and interpenetration of the polymer brushes as the plate separation is decreased, instead of the ``classical-limit'' picture of compression with no interpenetration.

  9. Polymer infiltration studies

    NASA Technical Reports Server (NTRS)

    Marchello, Joseph M.

    1995-01-01

    Polymer infiltration investigations were directed toward development of methods by which to produce advanced composite material for automated part fabrication utilizing textile and robotic technology in the manufacture of subsonic and supersonic aircraft. Significant progress was made during the project on the preparation of carbon fiber composites using advanced polymer resins. The findings and results of the project are summarized in the attached paper entitled 'Powder-Coated Towpreg: Avenues to Near Net Shape Fabrication of High Performance Composite.' Also attached to this report is the second of two patent applications submitted as a result of these studies.

  10. The mechanics of manufacturing processes

    SciTech Connect

    Wright, P.; Stori, J.; King, C.

    1996-10-01

    Economic pressures, particularly related to the quality of manufactured goods and `time-to-market` are forcing designers to think not only in terms of product design but also in terms of integrated product and process design, and finally in terms of deterministic manufacturing planning and control. As a result of these three high level needs, there is now an even greater need for comprehensive simulations that predict material behavior during a manufacturing process, the stresses and/or temperatures on associated tooling, and the final-product integrity. The phrase `manufacturing processes` of course covers a broad scope; it includes semiconductor manufacturing, injection molding of polymers, metal machining and precision lapping, wood and textile production, and the final assembly of piece-parts into a consumer product. It can be seen from this partial listing that the fields of fluid mechanics, solid mechanics, dynamics and tribology can all play a role. The introduction to the paper will contain a review of manufacturing processes and describe where simulations have been successfully applied, and where simulations are still lacking. The best of the simulations are those where the models accurately fit the physical phenomena, where accurate constitutive equations are available, and where boundary conditions are realistic. Thus, the body of the paper will focus on the results from one of these more successful simulations. It has been used to predict the deflections of tooling and the most appropriate operating conditions for the manufacturing process under study. A new method for manufacturing planning is described. In this method, closed form, somewhat simplified, analytical models are used to determine manufacturing planning parameters and then the results from these simpler models are refined by the fuller simulations. A case study in machining parameter selection for peripheral finish milling operations is developed.

  11. Manufacture of electrical and magnetic graded and anisotropic materials for novel manipulations of microwaves.

    PubMed

    Grant, P S; Castles, F; Lei, Q; Wang, Y; Janurudin, J M; Isakov, D; Speller, S; Dancer, C; Grovenor, C R M

    2015-08-28

    Spatial transformations (ST) provide a design framework to generate a required spatial distribution of electrical and magnetic properties of materials to effect manipulations of electromagnetic waves. To obtain the electromagnetic properties required by these designs, the most common materials approach has involved periodic arrays of metal-containing subwavelength elements. While aspects of ST theory have been confirmed using these structures, they are often disadvantaged by narrowband operation, high losses and difficulties in implementation. An all-dielectric approach involves weaker interactions with applied fields, but may offer more flexibility for practical implementation. This paper investigates manufacturing approaches to produce composite materials that may be conveniently arranged spatially, according to ST-based designs. A key aim is to highlight the limitations and possibilities of various manufacturing approaches, to constrain designs to those that may be achievable. The article focuses on polymer-based nano- and microcomposites in which interactions with microwaves are achieved by loading the polymers with high-permittivity and high-permeability particles, and manufacturing approaches based on spray deposition, extrusion, casting and additive manufacture. PMID:26217051

  12. Manufacture of electrical and magnetic graded and anisotropic materials for novel manipulations of microwaves

    PubMed Central

    Grant, P. S.; Castles, F.; Lei, Q.; Wang, Y.; Janurudin, J. M.; Isakov, D.; Speller, S.; Dancer, C.; Grovenor, C. R. M.

    2015-01-01

    Spatial transformations (ST) provide a design framework to generate a required spatial distribution of electrical and magnetic properties of materials to effect manipulations of electromagnetic waves. To obtain the electromagnetic properties required by these designs, the most common materials approach has involved periodic arrays of metal-containing subwavelength elements. While aspects of ST theory have been confirmed using these structures, they are often disadvantaged by narrowband operation, high losses and difficulties in implementation. An all-dielectric approach involves weaker interactions with applied fields, but may offer more flexibility for practical implementation. This paper investigates manufacturing approaches to produce composite materials that may be conveniently arranged spatially, according to ST-based designs. A key aim is to highlight the limitations and possibilities of various manufacturing approaches, to constrain designs to those that may be achievable. The article focuses on polymer-based nano- and microcomposites in which interactions with microwaves are achieved by loading the polymers with high-permittivity and high-permeability particles, and manufacturing approaches based on spray deposition, extrusion, casting and additive manufacture. PMID:26217051

  13. Manufacturing technology

    SciTech Connect

    Blaedel, K L

    1998-01-01

    The mission of the Manufacturing Technology thrust area at Lawrence Livermore National Laboratory (LLNL) has been to have an adequate base of manufacturing technology, not necessarily resident at LLNL, to conduct their future business. The specific goals were (1) to develop an understanding of fundamental fabrication processes; (2) to construct general purpose process models that have wide applicability; (3) to document their findings and models in journals; (4) to transfer technology to LLNL programs, industry, and colleagues; and (5) to develop continuing relationships with the industrial and academic communities to advance their collective understanding of fabrication processes. In support of this mission, two projects were reported here, each of which explores a way to bring higher precision to the manufacturing challenges that we face over the next few years. The first, ''A Spatial-Frequency-Domain Approach to Designing a Precision Machine Tools,'' is an overall view of how they design machine tools and instruments to make or measure workpieces that are specified in terms of the spatial frequency content of the residual errors of the workpiece surface. This represents an improvement of an ''error budget,'' a design tool that saw significant development in the early 1980's, and has been in active use since then. The second project, ''Micro-Drilling of ICF Capsules,'' is an attempt to define the current state in commercial industry for drilling small holes, particularly laser-drilling. The report concludes that 1-{micro}m diameter holes cannot currently be drilled to high aspect ratios, and then defines the engineering challenges that will have to be overcome to machine holes small enough for NIF capsules.

  14. Microgravity Polymers

    NASA Technical Reports Server (NTRS)

    1986-01-01

    A one-day, interactive workshop considering the effects of gravity on polymer materials science was held in Cleveland, Ohio, on May 9, 1985. Selected programmatic and technical issues were reviewed to introduce the field to workshop participants. Parallel discussions were conducted in three disciplinary working groups: polymer chemistry, polymer physics, and polymer engineering. This proceedings presents summaries of the workshop discussions and conclusions.

  15. Polymer electronic devices and materials.

    SciTech Connect

    Schubert, William Kent; Baca, Paul Martin; Dirk, Shawn M.; Anderson, G. Ronald; Wheeler, David Roger

    2006-01-01

    Polymer electronic devices and materials have vast potential for future microsystems and could have many advantages over conventional inorganic semiconductor based systems, including ease of manufacturing, cost, weight, flexibility, and the ability to integrate a wide variety of functions on a single platform. Starting materials and substrates are relatively inexpensive and amenable to mass manufacturing methods. This project attempted to plant the seeds for a new core competency in polymer electronics at Sandia National Laboratories. As part of this effort a wide variety of polymer components and devices, ranging from simple resistors to infrared sensitive devices, were fabricated and characterized. Ink jet printing capabilities were established. In addition to promising results on prototype devices the project highlighted the directions where future investments must be made to establish a viable polymer electronics competency.

  16. Multiscale implications of stress-induced ionic polymer transducer sensing

    NASA Astrophysics Data System (ADS)

    Zangrilli, Ursula Therese

    Ionic Polymer Transducers (IPTs) can act as both actuators and sensors. As actuators, the energy density values are much better than PZT or PVDF materials. As sensors, IPTs are extraordinarily sensitive and have the potential to be used in any mode of deformation. However, application of IPT sensors is limited because of a lack of understanding of their fundamental physics. In this work, the main focus will be to explore and develop a better understanding of how IPTs function with respect to shear deformation. In turn, the results developed here will improve upon the state of understanding of IPT sensors in general and potentially expand meaningful application opportunities. Because IPT active response is a multiscale phenomenon, this study adopts a multiscale modeling framework. Of interest are the interplay among the polymeric backbone of the ionic polymer, the diluent present in the hydrophilic regions of the polymer and the interspersed electrode particulate. To begin, this work improves upon a past multiscale modeling framework for the polymer backbone based upon Rotational Isomeric State Theory such that the effects of material anisotropy may be considered. This is potentially significant in light of the polymer manufacturing process. These modeling results are then incorporated into a model of the diluent movement within the ionic transport regions of the IPT. The electrical current predictions are based upon streaming potential theories. Finally, this model incorporates viscoelastic behavior in order to develop a better understanding of the coupling of these two systems (the polymer and the diluent) and how this coupling influence affects the expected current output over time.

  17. Characterization of Tantalum Polymer Capacitors

    NASA Technical Reports Server (NTRS)

    Spence, Penelope

    2012-01-01

    Overview Reviewed data Caution must be taken when accelerating test conditions Data not useful to establish an acceleration model Introduction of new failure mechanism skewing results Evidence of Anti-Wear-Out De-doping of polymer Decreased capacitance Increased ESR Not dielectric breakdown Needs further investigation Further investigation into tantalum polymer capacitor technology Promising acceleration model for Manufacturer A Possibility for use in high-reliability space applications with suitable voltage derating.

  18. Polymer infiltration studies

    NASA Technical Reports Server (NTRS)

    Marchello, Joseph M.

    1992-01-01

    Progress was made in several areas on the preparation of carbon fiber composites using advanced polymer resins. Polymer infiltration studies dealt with ways of preparing composite materials from advanced polymer resins and carbon fibers. This effort is comprised of an integrated approach to the process of composite part fabrication. The goal is to produce advanced composite materials for automated part fabrication using textile and robotics technology in the manufacture of subsonic and supersonic aircraft. The object is achieved through investigations at the NASA Langley Research Center and by stimulating technology transfer between contract researchers and the aircraft industry. Covered here are literature reviews, a status report on individual projects, current and planned research, publications, and scheduled technical presentations.

  19. Charged polymers in high dimensions

    NASA Technical Reports Server (NTRS)

    Kantor, Yacov

    1990-01-01

    A Monte Carlo study of charged polymers with either homogeneously distributed frozen charges or with mobile charges has been performed in four and five space dimensions. The results are consistent with the renormalization-group predictions and contradict the predictions of Flory-type theory. Introduction of charge mobility does not modify the behavior of the polymers.

  20. Free-energy analysis of water affinity in polymer studied by atomistic molecular simulation combined with the theory of solutions in the energy representation

    NASA Astrophysics Data System (ADS)

    Kawakami, Tomonori; Shigemoto, Isamu; Matubayasi, Nobuyuki

    2012-12-01

    Affinity of small molecule to polymer is an essential property for designing polymer materials with tuned permeability. In the present work, we develop a computational approach to the free energy ΔG of binding a small solute molecule into polymer using the atomistic molecular dynamics (MD) simulation combined with the method of energy representation. The binding free energy ΔG is obtained by viewing a single polymer as a collection of fragments and employing an approximate functional constructed from distribution functions of the interaction energy between solute and the fragment obtained from MD simulation. The binding of water is then examined against 9 typical polymers. The relationship is addressed between the fragment size and the calculated ΔG, and a useful fragment size is identified to compromise the performance of the free-energy functional and the sampling efficiency. It is found with the appropriate fragment size that the ΔG convergence at a statistical error of ˜0.2 kcal/mol is reached at ˜4 ns of replica-exchange MD of the water-polymer system and that the mean absolute deviation of the computational ΔG from the experimental is 0.5 kcal/mol. The connection is further discussed between the polymer structure and the thermodynamic ΔG.

  1. Turbine Manufacture

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The machinery pictured is a set of Turbodyne steam turbines which power a sugar mill at Bell Glade, Florida. A NASA-developed computer program called NASTRAN aided development of these and other turbines manufactured by Turbodyne Corporation's Steam Turbine Division, Wellsville, New York. An acronym for NASA Structural Analysis Program, NASTRAN is a predictive tool which advises development teams how a structural design will perform under service use conditions. Turbodyne uses NASTRAN to analyze the dynamic behavior of steam turbine components, achieving substantial savings in development costs. One of the most widely used spinoffs, NASTRAN is made available to private industry through NASA's Computer Software Management Information Center (COSMIC) at the University of Georgia.

  2. Viscoelastic cationic polymers containing the urethane linkage

    NASA Technical Reports Server (NTRS)

    Rembaum, A. (Inventor)

    1972-01-01

    A method for the synthesis and manufacturing of elastomeric compositions and articles containing quaternary nitrogen centers and condensation residues along the polymeric backbone of the centers is presented. Linear and cross-linked straight chain and block polymers having a wide damping temperature range were synthesized. Formulae for the viscoelastic cationic polymers are presented.

  3. Review of polymer MEMS micromachining

    NASA Astrophysics Data System (ADS)

    Kim, Brian J.; Meng, Ellis

    2016-01-01

    The development of polymer micromachining technologies that complement traditional silicon approaches has enabled the broadening of microelectromechanical systems (MEMS) applications. Polymeric materials feature a diverse set of properties not present in traditional microfabrication materials. The investigation and development of these materials have opened the door to alternative and potentially more cost effective manufacturing options to produce highly flexible structures and substrates with tailorable bulk and surface properties. As a broad review of the progress of polymers within MEMS, major and recent developments in polymer micromachining are presented here, including deposition, removal, and release techniques for three widely used MEMS polymer materials, namely SU-8, polyimide, and Parylene C. The application of these techniques to create devices having flexible substrates and novel polymer structural elements for biomedical MEMS (bioMEMS) is also reviewed.

  4. Photoelectrochemical cells for conversion of solar energy to electricity and methods of their manufacture

    DOEpatents

    Skotheim, Terje

    1984-04-10

    A photoelectric device is disclosed which comprises first and second layers of semiconductive material, each of a different bandgap, with a layer of dry solid polymer electrolyte disposed between the two semiconductor layers. A layer of a polymer blend of a highly conductive polymer and a solid polymer electrolyte is further interposed between the dry solid polymer electrolyte and the first semiconductor layer. A method of manufacturing such devices is also disclosed.

  5. Emerging Materials Technologies That Matter to Manufacturers

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    2015-01-01

    A brief overview of emerging materials technologies. Exploring the weight reduction benefit of replacing Carbon Fiber with Carbon Nanotube (CNT) in Polymer Composites. Review of the benign purification method developed for CNT sheets. The future of manufacturing will include the integration of computational material design and big data analytics, along with Nanomaterials as building blocks.

  6. Polymer crowding and shape distributions in polymer-nanoparticle mixtures

    NASA Astrophysics Data System (ADS)

    Lim, Wei Kang; Denton, Alan R.

    2014-09-01

    Macromolecular crowding can influence polymer shapes, which is important for understanding the thermodynamic stability of polymer solutions and the structure and function of biopolymers (proteins, RNA, DNA) under confinement. We explore the influence of nanoparticle crowding on polymer shapes via Monte Carlo simulations and free-volume theory of a coarse-grained model of polymer-nanoparticle mixtures. Exploiting the geometry of random walks, we model polymer coils as effective penetrable ellipsoids, whose shapes fluctuate according to the probability distributions of the eigenvalues of the gyration tensor. Accounting for the entropic cost of a nanoparticle penetrating a larger polymer coil, we compute the crowding-induced shift in the shape distributions, radius of gyration, and asphericity of ideal polymers in a theta solvent. With increased nanoparticle crowding, we find that polymers become more compact (smaller, more spherical), in agreement with predictions of free-volume theory. Our approach can be easily extended to nonideal polymers in good solvents and used to model conformations of biopolymers in crowded environments.

  7. Polymer crowding and shape distributions in polymer-nanoparticle mixtures.

    PubMed

    Lim, Wei Kang; Denton, Alan R

    2014-09-21

    Macromolecular crowding can influence polymer shapes, which is important for understanding the thermodynamic stability of polymer solutions and the structure and function of biopolymers (proteins, RNA, DNA) under confinement. We explore the influence of nanoparticle crowding on polymer shapes via Monte Carlo simulations and free-volume theory of a coarse-grained model of polymer-nanoparticle mixtures. Exploiting the geometry of random walks, we model polymer coils as effective penetrable ellipsoids, whose shapes fluctuate according to the probability distributions of the eigenvalues of the gyration tensor. Accounting for the entropic cost of a nanoparticle penetrating a larger polymer coil, we compute the crowding-induced shift in the shape distributions, radius of gyration, and asphericity of ideal polymers in a theta solvent. With increased nanoparticle crowding, we find that polymers become more compact (smaller, more spherical), in agreement with predictions of free-volume theory. Our approach can be easily extended to nonideal polymers in good solvents and used to model conformations of biopolymers in crowded environments. PMID:25240374

  8. Polymer crowding and shape distributions in polymer-nanoparticle mixtures

    SciTech Connect

    Lim, Wei Kang; Denton, Alan R.

    2014-09-21

    Macromolecular crowding can influence polymer shapes, which is important for understanding the thermodynamic stability of polymer solutions and the structure and function of biopolymers (proteins, RNA, DNA) under confinement. We explore the influence of nanoparticle crowding on polymer shapes via Monte Carlo simulations and free-volume theory of a coarse-grained model of polymer-nanoparticle mixtures. Exploiting the geometry of random walks, we model polymer coils as effective penetrable ellipsoids, whose shapes fluctuate according to the probability distributions of the eigenvalues of the gyration tensor. Accounting for the entropic cost of a nanoparticle penetrating a larger polymer coil, we compute the crowding-induced shift in the shape distributions, radius of gyration, and asphericity of ideal polymers in a theta solvent. With increased nanoparticle crowding, we find that polymers become more compact (smaller, more spherical), in agreement with predictions of free-volume theory. Our approach can be easily extended to nonideal polymers in good solvents and used to model conformations of biopolymers in crowded environments.

  9. Piezoelectric Polymers

    NASA Technical Reports Server (NTRS)

    Harrison, J. S.; Ounaies, Z.; Bushnell, Dennis M. (Technical Monitor)

    2001-01-01

    The purpose of this review is to detail the current theoretical understanding of the origin of piezoelectric and ferroelectric phenomena in polymers; to present the state-of-the-art in piezoelectric polymers and emerging material systems that exhibit promising properties; and to discuss key characterization methods, fundamental modeling approaches, and applications of piezoelectric polymers. Piezoelectric polymers have been known to exist for more than forty years, but in recent years they have gained notoriety as a valuable class of smart materials.

  10. Two glass transitions in miscible polymer blends?

    SciTech Connect

    Dudowicz, Jacek; Freed, Karl F.; Douglas, Jack F.

    2014-06-28

    In contrast to mixtures of two small molecule fluids, miscible binary polymer blends often exhibit two structural relaxation times and two glass transition temperatures. Qualitative explanations postulate phenomenological models of local concentration enhancements due to chain connectivity in ideal, fully miscible systems. We develop a quantitative theory that explains qualitative trends in the dynamics of real miscible polymer blends which are never ideal mixtures. The theory is a synthesis of the lattice cluster theory of blend thermodynamics, the generalized entropy theory for glass-formation in polymer materials, and the Kirkwood-Buff theory for concentration fluctuations in binary mixtures.

  11. Optical and mechanical design advantages using polymer optics

    NASA Astrophysics Data System (ADS)

    Doushkina, Valentina; Fleming, Erik

    2009-08-01

    Precision diamond-turned or molded polymer optics are utilized in a wide range of commercial markets and applications including; medical disposables, bar code scan/recognition, security and fingerprint scanners, motion and presence sensors, CCD cameras, laser collimation and others.. The use of polymer optics was previously relegated to less technically challenging applications. Current advancements in polymer technology and injection molding capabilities have increased the manufacturability and precision of polymer optics. Polymer materials with optical properties are being thrust to the design forefront for new, sophisticated electro-optical applications. Designing and manufacturing optics and optical systems using polymers alone or hybrid polymer/glass applications provides complete custom capability and offers new optical and opto-mechanical solutions for a variety of optical and opto-mechanical modules, assemblies and components. Integrated mounting offers configuration flexibility, considerable design freedom, simplified optical alignment, mechanical design, assembly and packaging. The system is assembled, aligned, optically spaced, and sealed in a single manufacturing step.

  12. Seal Apparatus and Methods to Manufacture Thereof

    NASA Technical Reports Server (NTRS)

    Richard, James A. (Inventor)

    2013-01-01

    In some implementations, apparatus and methods are provided through which a dynamic cryogenic seal is manufactured. In some implementations, the seal includes a retainer and a spring-seal assembly, the assembly being comprised of a main spring housing and fluorine-containing polymer seals. In some implementations, either a radial seal, or an axial (or "piston seal") is provided. In some implementations, methods of manufacturing the dynamic cryogenic seal are also provided. In some implementations, the methods include assembling the components while either heated or cooled, taking advantage of thermal expansion and contraction, such that there is a strong interference fit between the components at room temperature. In some implementations, this process ensures that the weaker fluorine-containing polymer seal is forced to expand and contract with the stronger retainer and spring and is under constant preload. In some implementations, the fluorine-containing polymer is therefore fluidized and retained, and can not lift off.

  13. Crowding of polymer coils and demixing in nanoparticle-polymer mixtures.

    PubMed

    Lu, Ben; Denton, Alan R

    2011-07-20

    The Asakura-Oosawa-Vrij (AOV) model of colloid-polymer mixtures idealises nonadsorbing polymers as effective spheres that are fixed in size and impenetrable to hard particles. Real polymer coils, however, are intrinsically polydisperse in size (radius of gyration) and may be penetrated by smaller particles. Crowding by nanoparticles can affect the size distribution of polymer coils, thereby modifying effective depletion interactions and thermodynamic stability. To analyse the influence of crowding on polymer conformations and demixing phase behaviour, we adapt the AOV model to mixtures of nanoparticles and ideal, penetrable polymer coils that can vary in size. We perform Gibbs ensemble Monte Carlo simulations, including trial nanoparticle-polymer overlaps and variations in the radius of gyration. Results are compared with predictions of free-volume theory. Simulation and theory consistently predict that ideal polymers are compressed by nanoparticles, and that compressibility and penetrability stabilise nanoparticle-polymer mixtures. PMID:21709352

  14. Cloud manufacturing: a new manufacturing paradigm

    NASA Astrophysics Data System (ADS)

    Zhang, Lin; Luo, Yongliang; Tao, Fei; Li, Bo Hu; Ren, Lei; Zhang, Xuesong; Guo, Hua; Cheng, Ying; Hu, Anrui; Liu, Yongkui

    2014-03-01

    Combining with the emerged technologies such as cloud computing, the Internet of things, service-oriented technologies and high performance computing, a new manufacturing paradigm - cloud manufacturing (CMfg) - for solving the bottlenecks in the informatisation development and manufacturing applications is introduced. The concept of CMfg, including its architecture, typical characteristics and the key technologies for implementing a CMfg service platform, is discussed. Three core components for constructing a CMfg system, i.e. CMfg resources, manufacturing cloud service and manufacturing cloud are studied, and the constructing method for manufacturing cloud is investigated. Finally, a prototype of CMfg and the existing related works conducted by the authors' group on CMfg are briefly presented.

  15. Advanced Manufacturing Technologies

    NASA Technical Reports Server (NTRS)

    Fikes, John

    2016-01-01

    Advanced Manufacturing Technologies (AMT) is developing and maturing innovative and advanced manufacturing technologies that will enable more capable and lower-cost spacecraft, launch vehicles and infrastructure to enable exploration missions. The technologies will utilize cutting edge materials and emerging capabilities including metallic processes, additive manufacturing, composites, and digital manufacturing. The AMT project supports the National Manufacturing Initiative involving collaboration with other government agencies.

  16. Molecular madeling of amorphous polymers in the condensed phase

    SciTech Connect

    Curro, J.G.

    1997-12-31

    We have developed a tractable computational approach, PRISM theory (polymer Reference Interaction Site Model), for modeling structure and thermodynamics of polymer liquids and alloys. PRISM theory allows one to predict the effect of polymer architecture and monomer structure on the intermolecular packing in the condensed phase. Three applications of this method are discussed: phase behavior of polymer blends, solubility of gases in polymers, and structure of polymers near walls and interfaces. In these applications, nonrandom mixing effects (not included in previous theories) play an important role in the macroscopic properties of importance to the materials scientist.

  17. Thermodynamics of solutions containing hyperbranched polymers

    SciTech Connect

    Mio, C.; Lue, L.; Prausnitz, J.

    1996-12-31

    Vapor-liquid equilibria (VLE) have been obtained for solutions of hyperbranched polymers in chloroform, acetone, cyclohexane, methanol, acetonitrile or n-propylamine in the range 35 to 80{degrees}C. Polymers with different branched structures were studied: star, comb and dendritic polymers. Data interpretation is based on the lattice cluster theory (LCT) of Freed and coworkers. Unlike the Flory-Huggins theory, LCT can predict the effect of molecular architecture on thermodynamic solution properties.

  18. Desktop Manufacturing Technologies.

    ERIC Educational Resources Information Center

    Snyder, Mark

    1991-01-01

    Desktop manufacturing is the use of data from a computer-assisted design system to construct actual models of an object. Emerging processes are stereolithography, laser sintering, ballistic particle manufacturing, laminated object manufacturing, and photochemical machining. (SK)

  19. Sintering Theory and Practice

    NASA Astrophysics Data System (ADS)

    German, Randall M.

    1996-01-01

    process all around us--in manufactured objects from metals, ceramics, polymers, and many compounds. From a vast professional literature, Sintering Theory and Practice emerges as the only comprehensive, systematic, and self-contained volume on the subject. Covering all aspects of sintering as a processing topic, including materials, processes, theories, and the overall state of the art, the book Offers numerous examples, illustrations, and tables that detail actual processing cycles, and that stress existing knowledge in the field Uses the specifics of various consolidation cycles to illustrate the basics Leads the reader from the fundamentals to advanced topics, without getting bogged down in various mathematical disputes over treatments and measurements Supports the discussion with critically selected references from thousands of sources Examines the sintering behavior of a wide variety of engineered materials--metals, alloys, oxide ceramics, composites, carbides, intermetallics, glasses, and polymers Guides the reader through the sintering processes for several important industrial materials and demonstrates how to control these processes effectively and improve present techniques Provides a helpful reference for specific information on materials, processing problems, and concepts For practitioners and researchers in ceramics, powder metallurgy, and other areas, and for students and faculty in materials science and engineering, this book provides the know-how and understanding crucial to many industrial operations, offers many ideas for further research, and suggests future applications of this important technology. This book offers an unprecedented opportunity to explore sintering in both practical and theoretical terms, whether at the lab or in real-world applications, and to acquire a broad, yet thorough, understanding of this important technology.

  20. Computer modeling of polymers

    NASA Technical Reports Server (NTRS)

    Green, Terry J.

    1988-01-01

    A Polymer Molecular Analysis Display System (p-MADS) was developed for computer modeling of polymers. This method of modeling allows for the theoretical calculation of molecular properties such as equilibrium geometries, conformational energies, heats of formations, crystal packing arrangements, and other properties. Furthermore, p-MADS has the following capabilities: constructing molecules from internal coordinates (bonds length, angles, and dihedral angles), Cartesian coordinates (such as X-ray structures), or from stick drawings; manipulating molecules using graphics and making hard copy representation of the molecules on a graphics printer; and performing geometry optimization calculations on molecules using the methods of molecular mechanics or molecular orbital theory.

  1. Irreversibility and Polymer Adsorption

    NASA Astrophysics Data System (ADS)

    O'Shaughnessy, Ben; Vavylonis, Dimitrios

    2003-02-01

    Physisorption or chemisorption from dilute polymer solutions often entails irreversible polymer-surface bonding. We present a theory of the resultant nonequilibrium layers. While the density profile and loop distribution are the same as for equilibrium layers, the final layer comprises a tightly bound inner part plus an outer part whose chains make only fN surface contacts where N is chain length. The contact fractions f follow a broad distribution, P(f)˜f-4/5, in rather close agreement with strong physisorption experiments [

    H. M. Schneider et al., LangmuirLANGD50743-7463 12, 994 (1996)
    ].

  2. Algebraic models of flexible manufacturing systems

    NASA Astrophysics Data System (ADS)

    Leskin, Aleksei Alekseevich

    Various aspects of the use of mathematical methods in the development of flexible manufacturing systems are examined. Attention is given to dynamical and structural models of flexible manufacturing systems developed by using methods of algebraic and differential geometry, topology, polynomial algebra, and extreme value problem theory. The principles of model integration are discussed, and approaches are proposed for solving problems related to the selection of flexible manufacturing equipment, real-time modeling of the manufacturing process, and optimization of local automation systems. The discussion is illustrated by examples.

  3. Refractive Index Determination of Transparent Polymers: Experimental Setup for Multi-Wavelength Determination and Calculation at Specific Frequencies Using Group Contribution Theory

    ERIC Educational Resources Information Center

    Dlutowski, Jay; Cardenas-Valencia, Andres M.; Fries, David; Langebrake, Larry

    2006-01-01

    An experiment which enables students to determine the index of refraction at various wavelengths is demonstrated by using two polymers examples, poly(dimethyl siloxane) (PDMS) and poly(methyl methacrylate) (PMMA). This experiment would be suitable for a course in organic chemistry or any course discussing the optical properties of polymeric…

  4. Preparation of redox polymer cathodes for thin film rechargeable batteries

    DOEpatents

    Skotheim, Terje A.; Lee, Hung S.; Okamoto, Yoshiyuki

    1994-11-08

    The present invention relates to the manufacture of thin film solid state electrochemical devices using composite cathodes comprising a redox polymer capable of undergoing oxidation and reduction, a polymer solid electrolyte and conducting carbon. The polymeric cathode material is formed as a composite of radiation crosslinked polymer electrolytes and radiation crosslinked redox polymers based on polysiloxane backbones with attached organosulfur side groups capable of forming sulfur-sulfur bonds during electrochemical oxidation.

  5. Polymer Electrolytes

    NASA Astrophysics Data System (ADS)

    Hallinan, Daniel T.; Balsara, Nitash P.

    2013-07-01

    This review article covers applications in which polymer electrolytes are used: lithium batteries, fuel cells, and water desalination. The ideas of electrochemical potential, salt activity, and ion transport are presented in the context of these applications. Potential is defined, and we show how a cell potential measurement can be used to ascertain salt activity. The transport parameters needed to fully specify a binary electrolyte (salt + solvent) are presented. We define five fundamentally different types of homogeneous electrolytes: type I (classical liquid electrolytes), type II (gel electrolytes), type III (dry polymer electrolytes), type IV (dry single-ion-conducting polymer electrolytes), and type V (solvated single-ion-conducting polymer electrolytes). Typical values of transport parameters are provided for all types of electrolytes. Comparison among the values provides insight into the transport mechanisms occurring in polymer electrolytes. It is desirable to decouple the mechanical properties of polymer electrolyte membranes from the ionic conductivity. One way to accomplish this is through the development of microphase-separated polymers, wherein one of the microphases conducts ions while the other enhances the mechanical rigidity of the heterogeneous polymer electrolyte. We cover all three types of conducting polymer electrolyte phases (types III, IV, and V). We present a simple framework that relates the transport parameters of heterogeneous electrolytes to homogeneous analogs. We conclude by discussing electrochemical stability of electrolytes and the effects of water contamination because of their relevance to applications such as lithium ion batteries.

  6. Star Polymers.

    PubMed

    Ren, Jing M; McKenzie, Thomas G; Fu, Qiang; Wong, Edgar H H; Xu, Jiangtao; An, Zesheng; Shanmugam, Sivaprakash; Davis, Thomas P; Boyer, Cyrille; Qiao, Greg G

    2016-06-22

    Recent advances in controlled/living polymerization techniques and highly efficient coupling chemistries have enabled the facile synthesis of complex polymer architectures with controlled dimensions and functionality. As an example, star polymers consist of many linear polymers fused at a central point with a large number of chain end functionalities. Owing to this exclusive structure, star polymers exhibit some remarkable characteristics and properties unattainable by simple linear polymers. Hence, they constitute a unique class of technologically important nanomaterials that have been utilized or are currently under audition for many applications in life sciences and nanotechnologies. This article first provides a comprehensive summary of synthetic strategies towards star polymers, then reviews the latest developments in the synthesis and characterization methods of star macromolecules, and lastly outlines emerging applications and current commercial use of star-shaped polymers. The aim of this work is to promote star polymer research, generate new avenues of scientific investigation, and provide contemporary perspectives on chemical innovation that may expedite the commercialization of new star nanomaterials. We envision in the not-too-distant future star polymers will play an increasingly important role in materials science and nanotechnology in both academic and industrial settings. PMID:27299693

  7. Polymer Chemistry

    NASA Technical Reports Server (NTRS)

    Williams, Martha; Roberson, Luke; Caraccio, Anne

    2010-01-01

    This viewgraph presentation describes new technologies in polymer and material chemistry that benefits NASA programs and missions. The topics include: 1) What are Polymers?; 2) History of Polymer Chemistry; 3) Composites/Materials Development at KSC; 4) Why Wiring; 5) Next Generation Wiring Materials; 6) Wire System Materials and Integration; 7) Self-Healing Wire Repair; 8) Smart Wiring Summary; 9) Fire and Polymers; 10) Aerogel Technology; 11) Aerogel Composites; 12) Aerogels for Oil Remediation; 13) KSC's Solution; 14) Chemochromic Hydrogen Sensors; 15) STS-130 and 131 Operations; 16) HyperPigment; 17) Antimicrobial Materials; 18) Conductive Inks Formulations for Multiple Applications; and 19) Testing and Processing Equipment.

  8. Self-lubricating polymer composites and polymer transfer film lubrication for space applications

    NASA Technical Reports Server (NTRS)

    Fusaro, Robert L.

    1990-01-01

    The use of self-lubricating polymers and polymer composites in space is somewhat limited today. In general, they are only used when other methods are inadequate. There is potential, however, for these materials to make a significant impact on future space missions if properly utilized. Some of the different polymers and fillers used to make self-lubricating composites are surveyed. The mechanisms of composite lubrication and wear, the theory behind transfer film lubricating mechanisms, and some factors which affect polymer composite wear and transfer are examined. In addition, some of the current space tribology application areas for self-lubricating polymer composites and polymer transfer are mentioned.

  9. Exploring Manufacturing Technology.

    ERIC Educational Resources Information Center

    Iley, John; And Others

    These teacher's materials for an eight-unit course were developed to help students develop technological literacy, career exploration, and problem-solving skills relative to the manufacturing industries. The eight units include an overview of manufacturing, manufacturing enterprises and systems, manufacturing materials and selection, manufacturing…

  10. Deformation-Induced Anisotropy of Polymers

    NASA Technical Reports Server (NTRS)

    Peng, S. T. J.; Landel, R. F.

    1982-01-01

    New theory calculates anisotropies induced by large deformations in polymers. Theory was developed primarily for calculating anistropy of thermal expansivity, but is also applicable to thermal conductivity, elastic moduli and other properties. Theory assumes that in isotropic state, long polymer chains are randomly coiled and not oriented in particular direction. They acquire an orientation when material is deformed. As average molecular orientation increases with deformation, properties of bulk material exhibit averaging of the microscopic anistropies of the oriented molecular segments.

  11. Polymer Informatics

    NASA Astrophysics Data System (ADS)

    Adams, Nico

    Polymers are arguably the most important set of materials in common use. The increasing adoption of both combinatorial as well as high-throughput approaches, coupled with an increasing amount of interdisciplinarity, has wrought tremendous change in the field of polymer science. Yet the informatics tools required to support and further enhance these changes are almost completely absent. In the first part of the chapter, a critical analysis of the challenges facing modern polymer informatics is provided. It is argued, that most of the problems facing the field today are rooted in the current scholarly communication process and the way in which chemists and polymer scientists handle and publish data. Furthermore, the chapter reviews existing modes of representing and communicating polymer information and discusses the impact, which the emergence of semantic technologies will have on the way in which scientific and polymer data is published and transmitted. In the second part, a review of the use of informatics tools for the prediction of polymer properties and in silico design of polymers is offered.

  12. Polymers & People

    ERIC Educational Resources Information Center

    Lentz, Linda; Robinson, Thomas; Martin, Elizabeth; Miller, Mary; Ashburn, Norma

    2004-01-01

    Each Tuesday during the fall of 2002, teams of high school students from three South Carolina counties conducted a four-hour polymer institute for their peers. In less than two months, over 300 students visited the Charleston County Public Library in Charleston, South Carolina, to explore DNA, nylon, rubber, gluep, and other polymers. Teams of…

  13. IUPAC International Symposium on Polymers for Advanced Technologies, Jerusalem, Israel, Aug. 16-21, 1987, Proceedings

    SciTech Connect

    Lewin, M.

    1988-01-01

    The present conference discusses topics in radiation-sensitive, radiation-modified, and cured polymers, polymers of photoconductive, electroconductive, and piezoelectric type, polymers for advanced structures, liquid-crystal polymers, high-performance polymers compounded from flexible macromolecules, polymer networks, polymer blends, and the matching of composites with adhesives. Attention is given to the industrial radiation-curing of polymers, a frequency-analysis of ferroelectricity, liquid crystal polyester fibers, photochromic and thermochromic liquid crystals, diacetylene-based single-crystal fibers, interpenetrating polymer networks, chain-length development in complex epoxy-amine matrices, and a statistical-thermodynamic theory of polymer precipitation fractionation.

  14. Blade Manufacturing Improvement: Remote Blade Manufacturing Demonstration

    SciTech Connect

    ASHWILL, THOMAS D.

    2003-05-01

    The objective of this program was to investigate manufacturing improvements for wind turbine blades. The program included a series of test activities to evaluate the strength, deflection, performance, and loading characteristics of the prototype blades. The original contract was extended in order to continue development of several key blade technologies identified in the project. The objective of the remote build task was to demonstrate the concept of manufacturing wind turbine blades at a temporary manufacturing facility in a rural environment. TPI Composites successfully completed a remote manufacturing demonstration in which four blades were fabricated. The remote demonstration used a manufacturing approach which relied upon material ''kits'' that were organized in the factory and shipped to the site. Manufacturing blades at the wind plant site presents serious logistics difficulties and does not appear to be the best approach. A better method appears to be regional manufacturing facilities, which will eliminate most of the transportation cost, without incurring the logistical problems associated with fabrication directly onsite. With this approach the remote facilities would use commonly available industrial infrastructure such as enclosed workbays, overhead cranes, and paved staging areas. Additional fatigue testing of the M20 root stud design was completed with good results. This design provides adhesive bond strength under fatigue loading that exceeds that of the fastener. A new thru-stud bonding concept was developed for the M30 stud design. This approach offers several manufacturing advantages; however, the test results were inconclusive.

  15. Modeling aligning effect of polymer network in polymer stabilized nematic liquid crystals

    NASA Astrophysics Data System (ADS)

    Yang, Deng-Ke; Cui, Yue; Nemati, Hossein; Zhou, Xiaochen; Moheghi, Alireza

    2013-12-01

    We developed a phenomenological theory to describe the aligning field of polymer networks in polymer stabilized liquid crystals where sub-micron size polymer networks are phase separated from the liquid crystal in dispersion. The polymer networks are anisotropic and anchor the liquid crystals in their longitudinal direction. They inhibit the liquid crystals reorientation when external stimuli, such as electric field and temperature, are applied and reduce the relaxation time from distorted states. We model the effects produced by the polymer networks as an effective aligning field. We calculate the effective field as a function of the polymer network volume fraction and the lateral size of the network. The theory is compared with experimental results and good agreements were obtained. It is very useful in predicting how much polymer networks change the driving voltage and response time of liquid crystal devices.

  16. Organometallic Polymers.

    ERIC Educational Resources Information Center

    Carraher, Charles E., Jr.

    1981-01-01

    Reactions utilized to incorporate a metal-containing moiety into a polymer chain (addition, condensation, and coordination) are considered, emphasizing that these reactions also apply to smaller molecules. (JN)

  17. Polymer flooding

    SciTech Connect

    Littmann, W.

    1988-01-01

    This book covers all aspects of polymer flooding, an enhanced oil recovery method using water soluble polymers to increase the viscosity of flood water, for the displacement of crude oil from porous reservoir rocks. Although this method is becoming increasingly important, there is very little literature available for the engineer wishing to embark on such a project. In the past, polymer flooding was mainly the subject of research. The results of this research are spread over a vast number of single publications, making it difficult for someone who has not kept up-to-date with developments during the last 10-15 years to judge the suitability of polymer flooding to a particular field case. This book tries to fill that gap. An indispensable book for reservoir engineers, production engineers and lab. technicians within the petroleum industry.

  18. Manufacturing control: A basis for analysis

    NASA Astrophysics Data System (ADS)

    Bugg, N.

    1989-11-01

    The application of elementary control theory to manufacturing systems demonstrating how the organization of basic shop-floor logistics can be optimized prior to the introduction of computer technology is explored. A control structure is introduced and applied to manufacturing systems, breaking the problem into its constituent parts in such a way that the advantages of improved control technology become more apparent and more readily implementable.

  19. Energy Use in Manufacturing

    EIA Publications

    2006-01-01

    This report addresses both manufacturing energy consumption and characteristics of the manufacturing economy related to energy consumption. In addition, special sections on fuel switching capacity and energy-management activities between 1998 and 2002 are also featured in this report.

  20. Feed Formulation and Manufacture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter provides information on feed formulation and manufacture. To formulate and manufacture high quality fish feeds, including tilapia feeds, one should have knowledge of nutrient requirements, nutrient composition, digestibility, and availability of feed ingredients; impacts of manufacturin...

  1. Polymers All Around You!

    ERIC Educational Resources Information Center

    Gertz, Susan

    Background information on natural polymers, synthetic polymers, and the properties of polymers is presented as an introduction to this curriculum guide. Details are provided on the use of polymer products in consumer goods, polymer recycling, polymer densities, the making of a polymer such as GLUEP, polyvinyl alcohol, dissolving plastics, polymers…

  2. Depletion-induced forces and crowding in polymer-nanoparticle mixtures: Role of polymer shape fluctuations and penetrability

    NASA Astrophysics Data System (ADS)

    Lim, Wei Kang; Denton, Alan R.

    2016-01-01

    Depletion forces and macromolecular crowding govern the structure and function of biopolymers in biological cells and the properties of polymer nanocomposite materials. To isolate and analyze the influence of polymer shape fluctuations and penetrability on depletion-induced interactions and crowding by nanoparticles, we model polymers as effective penetrable ellipsoids, whose shapes fluctuate according to the probability distributions of the eigenvalues of the gyration tensor of an ideal random walk. Within this model, we apply Monte Carlo simulation methods to compute the depletion-induced potential of mean force between hard nanospheres and crowding-induced shape distributions of polymers in the protein limit, in which polymer coils can be easily penetrated by smaller nanospheres. By comparing depletion potentials from simulations of ellipsoidal and spherical polymer models with predictions of polymer field theory and free-volume theory, we show that polymer depletion-induced interactions and crowding depend sensitively on polymer shapes and penetrability, with important implications for bulk thermodynamic phase behavior.

  3. Neutron Characterization for Additive Manufacturing

    NASA Technical Reports Server (NTRS)

    Watkins, Thomas; Bilheux, Hassina; An, Ke; Payzant, Andrew; DeHoff, Ryan; Duty, Chad; Peter, William; Blue, Craig; Brice, Craig A.

    2013-01-01

    Manufacturing Demonstration Facility (MDF) sponsored by the DOE's Advanced Manufacturing Office. The MDF is focusing on R&D of both metal and polymer AM pertaining to in-situ process monitoring and closed-loop controls; implementation of advanced materials in AM technologies; and demonstration, characterization, and optimization of next-generation technologies. ORNL is working directly with industry partners to leverage world-leading facilities in fields such as high performance computing, advanced materials characterization, and neutron sciences to solve fundamental challenges in advanced manufacturing. Specifically, MDF is leveraging two of the world's most advanced neutron facilities, the HFIR and SNS, to characterize additive manufactured components.

  4. Workforce Development for Manufacturing

    ERIC Educational Resources Information Center

    Bernard, Rosalie

    2007-01-01

    In a recent skills gap report, the National Association of Manufacturers (NAM) noted some disturbing trends in the gap between the demand for highly skilled manufacturing workers and the potential supply. The NAM report notes that smaller manufacturers rank finding qualified workers ahead of energy costs, taxes and government regulations on the…

  5. Relaxation dynamics of branched polymers

    NASA Astrophysics Data System (ADS)

    Ghosh, Arnav

    The Rouse model for star polymers was successfully derived by solving the differential equations governing the net force acting on each bead in a star polymer chain. As opposed to a linear polymer, where we have N unique roots for N beads, in the case of star polymers, there are only 2 Na+1 unique roots and all odd unique roots (except the last root corresponding to the branch point) starting with the first root have a multiplicity of f-1. The relaxation time of the pth unique Rouse mode of a star polymer varies as (2Na + 1)2/p2. Since alternate Rouse modes in a star polymer have a multiplicity of f-1, they add to the terminal modulus of the star polymers and the terminal modulus, G(tau) ends up being proportional to f-1 (besides being inversely proportional to N, which is also the case with linear polymers). A self-consistent theory for the relaxation of entangled star polymers was developed based on the work done by Colby and Rubinstein on linear blends. This theory considers the duality of relaxation dynamics (direct stress relaxation and indirect relaxation by release of constraints) and models the relaxation due to constraint release R(t) based on Dean's approach in solving the vibration frequencies of glassy chains with random spring constants. In our case, the mobilities of beads were considered to be random and based on the relative weight of the prefactor of a Maxwell function, a group of which was fitted to the stress relaxation function mu(t) of a star polymer (proposed and derived by Doi). The tube dilation model for star and comb polymers was investigated in detail and predictions compared to rheological data from polypropylene, polybutadiene and polystyrene comb polymers along with PEP star polymers. The relaxation time from the Tube Dilation Model was compared with the classical Tube Model and was shown to have an extra power dependence on the fraction of the comb backbone.

  6. Variable stiffness property study on shape memory polymer composite tube

    NASA Astrophysics Data System (ADS)

    Chen, Yijin; Sun, Jian; Liu, Yanju; Leng, Jinsong

    2012-09-01

    As a typical smart material, shape memory polymers (SMPs) have the capability of variable stiffness in response to external stimuli, such as heat, electricity, magnetism and solvents. In this research, a shape memory polymer composite (SMPC) tube composed of multi-layered filament wound structures is investigated. The SMPC tube possesses considerable flexibility under high temperature and rigidity under low temperature. Significant changes in effective engineering modulus can be achieved through regulating the environment temperature. Based on the classical laminated-plate theory and Sun’s thick laminate analysis, a 3D theory method is used to study the effective engineering modulus and modulus ratio of the SMPC tube. The tensile test is conducted on the SMPC tube to verify the accuracy of the theoretical method. In addition, the effective engineering modulus and modulus ratio are discussed under different fiber-winding angles and fiber volume fractions of the SMPC tube. The presented analysis provides meaningful guidance to assist the design and manufacture of SMPC tubes in morphing skin applications.

  7. Manufacturing Planning Guide

    NASA Technical Reports Server (NTRS)

    Waid, Michael

    2011-01-01

    Manufacturing process, milestones and inputs are unknowns to first-time users of the manufacturing facilities. The Manufacturing Planning Guide aids in establishing expectations for both NASA and non-NASA facility customers. The potential audience for this guide includes both internal and commercial spaceflight hardware/software developers. It is intended to assist their project engineering personnel in manufacturing planning and execution. Material covered includes a roadmap of the manufacturing process, roles and responsibilities of facility and user, major milestones, facility capabilities, and inputs required by the facility. Samples of deliverables, products, and inputs necessary to define test scope, cost, and schedule are included as an appendix to the guide.

  8. NMR and optical studies of piezoelectric polymers

    SciTech Connect

    Schmidt, V.H.; Tuthill, G.F.

    1993-01-01

    Progress is reported in several areas dealing with piezoelectric (electroactive) polymers (mostly vinylidene fluoride, trifluoroethylene, copolymers, PVF[sub 2]) and liquid crystals. Optical studies, neutron scattering, NMR, thermal, theory and modeling were done.

  9. Polymer quantum mechanics and its continuum limit

    SciTech Connect

    Corichi, Alejandro; Vukasinac, Tatjana; Zapata, Jose A.

    2007-08-15

    A rather nonstandard quantum representation of the canonical commutation relations of quantum mechanics systems, known as the polymer representation, has gained some attention in recent years, due to its possible relation with Planck scale physics. In particular, this approach has been followed in a symmetric sector of loop quantum gravity known as loop quantum cosmology. Here we explore different aspects of the relation between the ordinary Schroedinger theory and the polymer description. The paper has two parts. In the first one, we derive the polymer quantum mechanics starting from the ordinary Schroedinger theory and show that the polymer description arises as an appropriate limit. In the second part we consider the continuum limit of this theory, namely, the reverse process in which one starts from the discrete theory and tries to recover back the ordinary Schroedinger quantum mechanics. We consider several examples of interest, including the harmonic oscillator, the free particle, and a simple cosmological model.

  10. Peridynamic modeling and simulation of polymer-nanotube composites

    NASA Astrophysics Data System (ADS)

    Henke, Steven F.

    In this document, we develop and demonstrate a framework for simulating the mechanics of polymer materials that are reinforced by carbon nanotubes. Our model utilizes peridynamic theory to describe the mechanical response of the polymer and polymer-nanotube interfaces. We benefit from the continuum formulation used in peridynamics because (1) it allows the polymer material to be coarse-grained to the scale of the reinforcing nanofibers, and (2) failure via nanotube pull-out and matrix tearing are possible based on energetic considerations alone (i.e. without special treatment). To reduce the degrees of freedom that must be simulated, the reinforcement effect of the nanotubes is represented by a mesoscale bead-spring model. This approach permits the arbitrary placement of reinforcement ``strands'' in the problem domain and motivates the need for irregular quadrature point distributions, which have not yet been explored in the peridynamic setting. We address this matter in detail and report on aspects of mesh sensitivity that we uncovered in peridynamic simulations. Using a manufactured solution, we study the effects of quadrature point placement on the accuracy of the solution scheme in one and two dimensions. We demonstrate that square grids and the generator points of a centroidal Voronoi tessellation (CVT) support solutions of similar accuracy, but CVT grids have desirable characteristics that may justify the additional computational cost required for their construction. Impact simulations provide evidence that CVT grids support fracture patterns that resemble those obtained on higher resolution cubic Cartesian grids with a reduced computational burden. With the efficacy of irregular meshing schemes established, we exercise our model by dynamically stretching a cylindrical specimen composed of the polymer-nanotube composite. We vary the number of reinforcements, alignment of the filler, and the properties of the polymer-nanotube interface. Our results suggest

  11. Polymer composites technology in Japan

    SciTech Connect

    Karbhari, V.M.; Kukich, D.S. . Center for Composite Materials)

    1993-08-01

    In 1992, the National Science Foundation, Department of Energy, Army Research Office, and Air Force Office of Scientific Research convened a panel to assess advanced manufacturing technology for polymer composite structures in Japan. The panel was charged with comparing the levels of the technology and the industry in both the United States and Japan. The Panel on Advanced Polymer Composites Manufacturing Technology of the Japanese Technology Evaluation Center visited approximately twenty Japanese organizations over a ten-day period in December 1992. Their findings cover seven areas: aerospace, sporting goods, automotive, civil engineering, materials, manufacturing science, and product and process development methods. This report reflects the views of the authors, not necessarily those of the entire panel. The panel observed five emerging techno-paradigm shifts in Japan, previously identified by Kodama: Manufacturing companies; Business dynamics; R and D activities; Technology development; and Technology diffusion. Thus, what the panel observed in the specific area of advanced materials really reflects the overall Japanese approach to technology development. Their primary focus is on finding innovative new applications for existing materials, processes, and technologies, and on using these market opportunities to drive new development.

  12. Physical and Electrical Characterization of Aluminum Polymer Capacitors

    NASA Technical Reports Server (NTRS)

    Liu, David; Sampson, Michael J.

    2010-01-01

    Polymer aluminum capacitors from several manufacturers with various combinations of capacitance, rated voltage, and ESR values were physically examined and electrically characterized. The physical construction analysis of the capacitors revealed three different capacitor structures, i.e., traditional wound, stacked, and laminated. Electrical characterization results of polymer aluminum capacitors are reported for frequency-domain dielectric response at various temperatures, surge breakdown voltage, and other dielectric properties. The structure-property relations in polymer aluminum capacitors are discussed.

  13. Polymers containing borane or carborane cage compounds and related applications

    DOEpatents

    Bowen, III, Daniel E; Eastwood, Eric A

    2013-04-23

    Polymers comprising residues of cage compound monomers having at least one polyalkoxy silyl substituent are provided. The cage compound monomers are selected from borane cage compound monomers comprising at least 7 cage atoms and/or carborane cage compound monomers comprising 7 to 11 cage compound monomers. Such polymers can further comprise one or more reactive matrices and/or co-monomers covalently bound with the cage compound monomer residues. Articles of manufacture comprising such polymers are also disclosed.

  14. Physical and Electrical Characterization of Polymer Aluminum Capacitors

    NASA Technical Reports Server (NTRS)

    Liu, David; Sampson, Michael J.

    2010-01-01

    Polymer aluminum capacitors from several manufacturers with various combinations of capacitance, rated voltage, and ESR values were physically examined and electrically characterized. The physical construction analysis of the capacitors revealed three different capacitor structures, i.e., traditional wound, stacked, and laminated. Electrical characterization results of polymer aluminum capacitors are reported for frequency-domain dielectric response at various temperatures, surge breakdown voltage, and other dielectric properties. The structure-property relations in polymer aluminum capacitors are discussed.

  15. Antimocrobial Polymer

    DOEpatents

    McDonald, William F.; Huang, Zhi-Heng; Wright, Stacy C.

    2005-09-06

    A polymeric composition having antimicrobial properties and a process for rendering the surface of a substrate antimicrobial are disclosed. The composition comprises a crosslinked chemical combination of (i) a polymer having amino group-containing side chains along a backbone forming the polymer, (ii) an antimicrobial agent selected from quaternary ammonium compounds, gentian violet compounds, substituted or unsubstituted phenols, biguanide compounds, iodine compounds, and mixtures thereof, and (iii) a crosslinking agent containing functional groups capable of reacting with the amino groups. In one embodiment, the polymer is a polyamide formed from a maleic anhydride or maleic acid ester monomer and alkylamines thereby producing a polyamide having amino substituted alkyl chains on one side of the polyamide backbone; the crosslinking agent is a phosphine having the general formula (A)3P wherein A is hydroxyalkyl; and the antimicrobial agent is chlorhexidine, dimethylchlorophenol, cetyl pyridinium chloride, gentian violet, triclosan, thymol, iodine, and mixtures thereof.

  16. Antimicrobial Polymer

    DOEpatents

    McDonald, William F.; Wright, Stacy C.; Taylor, Andrew C.

    2004-09-28

    A polymeric composition having antimicrobial properties and a process for rendering the surface of a substrate antimicrobial are disclosed. The polymeric composition comprises a crosslinked chemical combination of (i) a polymer having amino group-containing side chains along a backbone forming the polymer, (ii) an antimicrobial agent selected from metals, metal alloys, metal salts, metal complexes and mixtures thereof, and (iii) a crosslinking agent containing functional groups capable of reacting with the amino groups. In one example embodiment, the polymer is a polyamide formed from a maleic anhydride or maleic acid ester monomer and alkylamines thereby producing a polyamide having amino substituted alkyl chains on one side of the polyamide backbone; the crosslinking agent is a phosphine having the general formula (A).sub.3 P wherein A is hydroxyalkyl; and the metallic antimicrobial agent is selected from chelated silver ions, silver metal, chelated copper ions, copper metal, chelated zinc ions, zinc metal and mixtures thereof.

  17. Polymer inflation

    NASA Astrophysics Data System (ADS)

    Hassan, Syed Moeez; Husain, Viqar; Seahra, Sanjeev S.

    2015-03-01

    We consider the semiclassical dynamics of a free massive scalar field in a homogeneous and isotropic cosmological spacetime. The scalar field is quantized using the polymer quantization method assuming that it is described by a Gaussian coherent state. For quadratic potentials, the semiclassical equations of motion yield a universe that has an early "polymer inflation" phase which is generic and almost exactly de Sitter, followed by an epoch of slow-roll inflation. We compute polymer corrections to the slow-roll formalism, and discuss the probability of inflation in this model using a physical Hamiltonian arising from time gauge fixing. We also show how in this model, it is possible to obtain a significant amount of slow-roll inflation from sub-Planckian initial data, hence circumventing some of the criticisms of standard scenarios. These results show the extent to which a quantum gravity motivated quantization method affects early universe dynamics.

  18. Water-Based Coating Simplifies Circuit Board Manufacturing

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Structures and Materials Division at Glenn Research Center is devoted to developing advanced, high-temperature materials and processes for future aerospace propulsion and power generation systems. The Polymers Branch falls under this division, and it is involved in the development of high-performance materials, including polymers for high-temperature polymer matrix composites; nanocomposites for both high- and low-temperature applications; durable aerogels; purification and functionalization of carbon nanotubes and their use in composites; computational modeling of materials and biological systems and processes; and developing polymer-derived molecular sensors. Essentially, this branch creates high-performance materials to reduce the weight and boost performance of components for space missions and aircraft engine components. Under the leadership of chemical engineer, Dr. Michael Meador, the Polymers Branch boasts world-class laboratories, composite manufacturing facilities, testing stations, and some of the best scientists in the field.

  19. Field theoretic simulations of polymer nanocomposites

    SciTech Connect

    Koski, Jason; Chao, Huikuan; Riggleman, Robert A.

    2013-12-28

    Polymer field theory has emerged as a powerful tool for describing the equilibrium phase behavior of complex polymer formulations, particularly when one is interested in the thermodynamics of dense polymer melts and solutions where the polymer chains can be accurately described using Gaussian models. However, there are many systems of interest where polymer field theory cannot be applied in such a straightforward manner, such as polymer nanocomposites. Current approaches for incorporating nanoparticles have been restricted to the mean-field level and often require approximations where it is unclear how to improve their accuracy. In this paper, we present a unified framework that enables the description of polymer nanocomposites using a field theoretic approach. This method enables straightforward simulations of the fully fluctuating field theory for polymer formulations containing spherical or anisotropic nanoparticles. We demonstrate our approach captures the correlations between particle positions, present results for spherical and cylindrical nanoparticles, and we explore the effect of the numerical parameters on the performance of our approach.

  20. Recent Advances in Simulation of Dendritic Polymers

    SciTech Connect

    Cagin, Tahir; Miklis, Paul J.; Wang, Guofeng; Zamanakos, Georgios; Martin, Ryan; Li, Hao; Mainz, Daniel T.; Nagarajan, V.; Goddard, William A.

    1999-05-11

    Dendrimers and hyperbranched polymers represent a revolution in methodology for directed synthesis of monodisperse polymers with enormous possibility of novel architectures. They demonstrate the ability to attain micelle-like structures with distinct internal and external character. Furthermore, the polyfunctional character of dendrimers allows varied response to environment and promise as selective sensors, carrier for drugs, encapsulation of toxic chemicals and metals. One of the key problems is the characterization of the structures. Theory and simulation can be essential to provide and predict structure and properties. We present some recent advances in theory, modeling and simulation of dendritic polymers.

  1. Manufacturing with the Sun

    NASA Technical Reports Server (NTRS)

    Murphy, Lawrence M.; Hauser, Steven G.; Clyne, Richard J.

    1991-01-01

    Concentrated solar radiation is now a viable alternative source for many advanced manufacturing processes. Researchers at the National Renewable Energy Laboratory (NREL) have demonstrated the feasibility of processes such as solar induced surface transformation of materials (SISTM), solar based manufacturing, and solar pumped lasers. Researchers are also using sunlight to decontaminate water and soils polluted with organic compounds; these techniques could provide manufacturers with innovative alternatives to traditional methods of waste management. The solar technology that is now being integrated into today's manufacturing processes offer greater potential for tomorrow, especially as applied to the radiation abundant environment available in space and on the lunar surface.

  2. Manufacturing with the Sun

    NASA Astrophysics Data System (ADS)

    Murphy, L. M.; Hauser, S. G.; Clyne, R. J.

    1992-05-01

    Concentrated solar radiation is now a viable alternative energy source for many advanced manufacturing processes. Researchers at the National Renewable Energy Laboratory (NREL) have demonstrated the feasibility of processes such as solar-induced surface transformation of materials (SISTM), solar-based manufacturing, and solar-pumped lasers. Researchers are also using sunlight to decontaminate water and soils polluted with organic compounds; these techniques could provide manufacturers with innovative alternatives to traditional methods of waste management. The solar technology that is now being integrated into today's manufacturing processes offers even greater potential for tomorrow, especially as applied to the radiation-abundant environment available in space and on the lunar surface.

  3. Polymer solutions

    SciTech Connect

    Krawczyk, Gerhard Erich; Miller, Kevin Michael

    2011-07-26

    There is provided a method of making a polymer solution comprising polymerizing one or more monomer in a solvent, wherein said monomer comprises one or more ethylenically unsaturated monomer that is a multi-functional Michael donor, and wherein said solvent comprises 40% or more by weight, based on the weight of said solvent, one or more multi-functional Michael donor.

  4. Polymer Science.

    ERIC Educational Resources Information Center

    Frank, Curtis W.

    1979-01-01

    Described is a series of four graduate level courses in polymer science, offered or currently in preparation, at Stanford University. Course descriptions and a list of required and recommended texts are included. Detailed course outlines for two of the courses are presented. (BT)

  5. Blowing Polymer Bubbles in an Acoustic Levitator

    NASA Technical Reports Server (NTRS)

    Lee, M. C.

    1985-01-01

    In new manufacturing process, small gas-filled polymer shells made by injecting gas directly into acoustically levitated prepolymer drops. New process allows sufficient time for precise control of shell geometry. Applications foreseen in fabrication of deuterium/tritium-filled fusion targets and in pharmaceutical coatings. New process also useful in glass blowing and blow molding.

  6. Thermoset epoxy polymers from renewable resources

    DOEpatents

    East, Anthony; Jaffe, Michael; Zhang, Yi; Catalani, Luiz H

    2009-11-17

    Novel thermoset epoxy polymers using the bisglycidyl ethers of anhydrosugars, such as isosorbide, isomannide, and isoidide, are disclosed. The bisglycidyl ethers are useful as substitutes for bisphenol A in the manufacture of thermoset epoxy ethers. The anhydrosugars are derived from renewable sources and the bisglycidyl ethers are not xenoestrogenic and the thermoset curing agents are likewise derived form renewable resources.

  7. Manufacturing tailored property ceramic composites

    SciTech Connect

    Ewsuk, K.G.; Harrison, L.W.

    1994-11-14

    Composite materials are desirable for many advanced engineering applications where the properties of a single phase material cannot meet all of the service requirements; however, existing process technology has limited the development and commercialization of composites. Lack of reproducible sintering to high density is one of the major obstacles to commercializing ceramic composites. Final-stage, non-reactive liquid phase sintering (NLPS) theory provides metrics for sinterability that can be used as guidelines to design and manufacture dense ceramic-filled-glass (CFG) composites. Additionally, within the constraints defined by the NLPS theory, sum-property models can be used to predict CFG composite properties, and to design composites with properties tailored to specific applications. By integrating composite process models with composite property models, processable, application-tailored CFG composites for microelectronics packaging have been designed and fabricated.

  8. Studies of light scattering and morphologies of phase-separated polymer/nanoparticle mixtures

    NASA Astrophysics Data System (ADS)

    Ding, Xuan

    Nowadays, solid "filler" particles can be found in many manufactured polymeric materials because of the enhanced thermal and mechanical properties these particles can offer. However, the influence of the "filler" particles, especially those with size on a nanoscopic scale, on the structural evolution of multicomponent systems, is still poorly understood. In this thesis, the spinodal decomposition (SD) of polystyrene/poly(vinyl methyl ether) (PS/PVME) polymer blend system mixed with different nanoparticles have been investigated by the small angle light scattering (SALS) technique. Interpreting the data using the Cahn-Hilliard linear theory and the scaling theory on early stage and late stage, respectively, we concluded that the addition of nanoparticles into the pure polymer blends can cause a retardation of the phase separation. Furthermore, experiments on polystyrene/poly(2-vinyl pyridine) (PS/P2VP) polymer blends mixed with polystyrene-covered gold nanoparticles (Au-PS) have shown that during the spinodal decomposition these Au-PS nanoparticles can self-assemble at the continuous PS/P2VP interface, due to the tendency to reduce interfacial energy, making it possible to create the so-called "bijel" structure (bicontinuous interfacially jammed emulsion jel). We believe that the "bijel" structures have a huge potential of being used in areas such as photovoltaics and catalysis, because of their large surface areas.

  9. Thermochromic polymer opals

    NASA Astrophysics Data System (ADS)

    Sussman, Jason; Snoswell, David; Kontogeorgos, Andreas; Baumberg, Jeremy J.; Spahn, Peter

    2009-10-01

    Large-scale shear-ordered photonic crystals are shown to exhibit unusual thermochromic properties. By balancing the refractive index of the polymer core and composite shell components at room temperature, transparent films are created, which become colored on heating to 150 °C. Since this scattering-based structural color depends only on resonant Bragg scattering of the unpigmented components, it can be tuned to any wavelength. The observed color shifts with temperature are not simply accounted for by theory and are sensitive to the constituents.

  10. Injection molded polymer optics in the 21st Century

    NASA Astrophysics Data System (ADS)

    Beich, William S.

    2005-08-01

    Precision polymer optics, manufactured by injection molding techniques, has been a key enabling technology for several decades now. The technology, which can be thought of as a subset of the wider field of precision optics manufacturing, was pioneered in the United States by companies such as Eastman Kodak, US Precision Lens, and Polaroid. In addition to suppliers in the U.S. there are several companies worldwide that design and manufacture precision polymer optics, for example Philips High Tech Plastics in Europe and Fujinon in Japan. Designers who are considering using polymer optics need a fundamental understanding of exactly how the optics are created. This paper will survey the technology and processes that are employed in the successful implementation of a polymer optic solution from a manufacturer's perspective. Special emphasis will be paid to the unique relationship between the molds and the optics that they produce. We will discuss the key elements of production: molding resins, molds and molding equipment, and metrology. Finally we will offer a case study to illustrate just how the optics designer carries a design concept through to production. The underlying theme throughout the discussion of polymer optics is the need for the design team to work closely with an experienced polymer optics manufacturer with a solid track record of success in molded optics. As will be seen shortly, the complex interaction between thermoplastics, molds, and molding machines dictates the need for working closely with a supplier who has the critical knowledge needed to manage all aspects of the program.

  11. Soft confinement for polymer solutions

    NASA Astrophysics Data System (ADS)

    Oya, Yutaka; Kawakatsu, Toshihiro

    2014-07-01

    As a model of soft confinement for polymers, we investigated equilibrium shapes of a flexible vesicle that contains a phase-separating polymer solution. To simulate such a system, we combined the phase field theory (PFT) for the vesicle and the self-consistent field theory (SCFT) for the polymer solution. We observed a transition from a symmetric prolate shape of the vesicle to an asymmetric pear shape induced by the domain structure of the enclosed polymer solution. Moreover, when a non-zero spontaneous curvature of the vesicle is introduced, a re-entrant transition between the prolate and the dumbbell shapes of the vesicle is observed. This re-entrant transition is explained by considering the competition between the loss of conformational entropy and that of translational entropy of polymer chains due to the confinement by the deformable vesicle. This finding is in accordance with the recent experimental result reported by Terasawa et al. (Proc. Natl. Acad. Sci. U.S.A., 108 (2011) 5249).

  12. Biodegradable Polymers and Stem Cells for Bioprinting.

    PubMed

    Lei, Meijuan; Wang, Xiaohong

    2016-01-01

    It is imperative to develop organ manufacturing technologies based on the high organ failure mortality and serious donor shortage problems. As an emerging and promising technology, bioprinting has attracted more and more attention with its super precision, easy reproduction, fast manipulation and advantages in many hot research areas, such as tissue engineering, organ manufacturing, and drug screening. Basically, bioprinting technology consists of inkjet bioprinting, laser-based bioprinting and extrusion-based bioprinting techniques. Biodegradable polymers and stem cells are common printing inks. In the printed constructs, biodegradable polymers are usually used as support scaffolds, while stem cells can be engaged to differentiate into different cell/tissue types. The integration of biodegradable polymers and stem cells with the bioprinting techniques has provided huge opportunities for modern science and technologies, including tissue repair, organ transplantation and energy metabolism. PMID:27136526

  13. Method for anisotropic etching in the manufacture of semiconductor devices

    DOEpatents

    Koontz, Steven L.; Cross, Jon B.

    1993-01-01

    Hydrocarbon polymer coatings used in microelectronic manufacturing processes are anisotropically etched by atomic oxygen beams (translational energies of 0.2-20 eV, preferably 1-10 eV). Etching with hyperthermal (kinetic energy>1 eV) oxygen atom species obtains highly anisotropic etching with sharp boundaries between etched and mask-protected areas.

  14. Multi-layer laminate structure and manufacturing method

    DOEpatents

    Keenihan, James R.; Cleereman, Robert J.; Eurich, Gerald; Graham, Andrew T.; Langmaid, Joe A.

    2012-04-24

    The present invention is premised upon a multi-layer laminate structure and method of manufacture, more particularly to a method of constructing the multi-layer laminate structure utilizing a laminate frame and at least one energy activated flowable polymer.

  15. Method for anisotropic etching in the manufacture of semiconductor devices

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor); Cross, Jon B. (Inventor)

    1993-01-01

    Hydrocarbon polymer coatings used in microelectronic manufacturing processes are anisotropically etched by hyperthermal atomic oxygen beams (translational energies of 0.2 to 20 eV, preferably 1 to 10 eV). Etching with hyperthermal oxygen atom species obtains highly anisotropic etching with sharp boundaries between etched and mask protected areas.

  16. Multi-layer laminate structure and manufacturing method

    SciTech Connect

    Keenihan, James R.; Cleereman, Robert J.; Eurich, Gerald; Graham, Andrew T.; Langmaid, Joe A.

    2013-01-29

    The present invention is premised upon a multi-layer laminate structure and method of manufacture, more particularly to a method of constructing the multi-layer laminate structure utilizing a laminate frame and at least one energy activated flowable polymer.

  17. Clean Energy Manufacturing Initiative

    SciTech Connect

    2013-04-01

    The initiative will strategically focus and rally EERE’s clean energy technology offices and Advanced Manufacturing Office around the urgent competitive opportunity for the United States to be the leader in the clean energy manufacturing industries and jobs of today and tomorrow.

  18. Manufacturing Education Curriculum Project.

    ERIC Educational Resources Information Center

    Umstattd, William D.

    The Manufacturing Education Curriculum Project's feasibility study concerned with industrial arts curriculum development in manufacturing for the senior high school level is described. The need for an industrial arts curriculum which meets and reflects present and future trends is discussed in the introduction, followed by a review of the…

  19. Developments in Agile Manufacturing

    SciTech Connect

    Clinesmith, M.G.

    1993-09-01

    As part of a project design initiative, Sandia National Laboratories and AlliedSignal Inc. Kansas City Division have joined efforts to develop a concurrent engineering capability for the manufacturing of complex precision components. The primary effort of this project, called Agile Manufacturing, is directed toward: (1) Understand the error associated with manufacturing and inspection. (2) Develop methods for correcting error. (3) Integrate diverse software technologies into a compatible process. The Agile Manufacturing System (AMS) is a system that integrates product design, manufacturing, and inspection into a closed loop, concurrent engineering process. The goal of developing the Agile Manufacturing System is to: (1) Optimize accuracy in manufacturing and inspection. (A) Use of softgage software for product evaluation. This will ensure ANSI Y14.5 compliance. (B) Establish and monitor bias between CMM and machine center. (C) Map probe deflection error and apply correction to inspection results. This applies to both on machine probing and CMM inspections. (D) Inspection process. (2) Compress the cycle time from product concept to production level manufacturing and verification. (3) Create a self-correcting process that feeds inspection results back into the machining process. (4) Link subordinate processes (cutting/probing path, softgage model, etc.) to the solid model definition.

  20. Manufacturing research strategic plan

    SciTech Connect

    1995-11-01

    This plan provides an overall strategic roadmap for the DOE-defense programs advanced manufacturing research program which supports the national science based stockpile stewardship program. This plan represents a vision required to develop the knowledge base needed to ensure an enduring national capability to rapidly and effectively manufacture nuclear weapons.

  1. Computer Aided Manufacturing.

    ERIC Educational Resources Information Center

    Insolia, Gerard

    This document contains course outlines in computer-aided manufacturing developed for a business-industry technology resource center for firms in eastern Pennsylvania by Northampton Community College. The four units of the course cover the following: (1) introduction to computer-assisted design (CAD)/computer-assisted manufacturing (CAM); (2) CAM…

  2. Mechanical properties of hybrid polymer nanotube systems

    NASA Astrophysics Data System (ADS)

    Coleman, Jonathan N.; Cadek, Martin; Dalton, Alan B.; Munoz, Edgar; Razal, Joselito; Baughman, Ray H.; Blau, Werner J.

    2003-04-01

    In this work, mechanical properties of hybrid materials fabricated from nanotubes and commercially available polymers were investigated. It was found that, by adding various concentrations of arc discharge multiwall nanotubes, both Young"s modulus and hardness increased by factors of 1.8 and 1.6 at 1wt% in PVA and 2.8 and 2.0 at 8wt% in PVK, in reasonable agreement with the Halpin-Tsai theory. Furthermore, the presence of the nanotubes was found to nucleate crystallization of the PVA. This crystal growth is thought to enhance matrix-nanotube stress transfer. In addition, microscopy studies suggest extremely strong interfacial bonding in the PVA-based composite. This is manifested by the fracture of the polymer rather that the polymer-nanotube interface. The dependence of the polymer nanotube interfacial interaction on host polymer was studied by intercalating various polymers (PVA, PVP and PS) into single wall nanotube buckypaper. Even for short soak times, significant polymer intercalation into existing free volume was observed. Depending on the polymer and the level of intercalation tensile tests on intercalated sheets showed that the Young"s modulus, strength and toughness increased by factors of 3, 9 and 28, respectively. This indicates that the intercalated polymer enhances load transmission between nanotubes due the significant stress transfer. The level of stress transfer was observed to scale with polymer hydrophobicity as expected.

  3. Embedded sensors in layered manufacturing

    NASA Astrophysics Data System (ADS)

    Li, Xiaochun

    Layered Manufacturing can be applied to build ``smart'' parts with sensors, integrated circuits, and actuators placed within the component. Embedded sensors can be used to gain data for validating or improving designs during the prototype stage or to obtain information on the performance and structural integrity of components in service. Techniques for embedding fiber optic sensors in metals, polymers, and ceramics have been investigated. Embedding optical fibers into metals is especially challenging because engineering alloys tend to exhibit high melting temperatures. In the present research an embedding sequence was developed capable of embedding fiber sensors into parts made of metal alloys with high melting temperatures. Fiber Bragg Grating (FBG) sensors were selected as the most promising sensor candidate. The embedded FBG sensors were characterized for temperature and strain measurements. The embedded FBG sensors in nickel and stainless steel provided high sensitivity, good accuracy, and high temperature capacity for temperature measurements. Temperature sensitivity approximately 100% higher than that of bare FBGs was demonstrated. For strain measurements, the sensors embedded in metal and polyurethane yielded high sensitivity, accuracy, and linearity. The sensitivity of the embedded FBGs was in good agreement with that of bare FBGs. Moreover, a decoupling technique for embedded FBG sensors was developed to separate temperature and strain effects. The embedded FBG sensors were used to monitor the accumulation of residual stresses during the laser- assisted Layered Manufacturing, to measure the strain field in layered materials, to measure pressure, and to monitor temperature and strain simultaneously. New techniques have been developed for temperature and strain measurements of rotating components with FBG sensors embedded or attached to the surface. Tunable laser diodes were incorporated into the sensing system for monitoring the Bragg grating wavelength

  4. Graphene/Polymer Nanocomposites

    NASA Astrophysics Data System (ADS)

    Macosko, Chris

    2010-03-01

    Graphite has attracted large attention as a reinforcement for polymers due to its ability to modify electrical conductivity, mechanical and gas barrier properties of host polymers and its potentially lower cost than carbon nanotubes. If graphite can be exfoliated into atomically thin graphene sheets, it is possible to achieve the highest property enhancements at the lowest loading. However, small spacing and strong van der Waals forces between graphene layers make exfoliation of graphite via conventional composite manufacturing strategies challenging. Recently, two different approaches to obtain exfoliated graphite prior to blending were reported: thermal treatment (Schniepp et al., JACS 2006) and chemical modification (Stankovich et al., J Mat Chem 2006). Both start from graphite oxide. We will describe and evaluate these exfoliation approaches and the methods used to produce graphene reinforced thermoplastics, particularly polyester, polycarbonate and polyurethane nanocomposites. Three different dispersion methods - melt blending, solution mixing and in-situ polymerization -- are compared. Characterization of dispersion quality is illustrated with TEM, rheology and in electrical conductivity, tensile modulus and gas barrier property improvement.

  5. Polymer powders for selective laser sintering (SLS)

    NASA Astrophysics Data System (ADS)

    Schmid, Manfred; Amado, Antonio; Wegener, Konrad

    2015-05-01

    Selective Laser Sintering (SLS) is close to be accepted as a production technique (Additive Manufacturing). However, one problem limiting employment of SLS for additive manufacturing in a wide-ranging industrial scope is the narrow variety of applicable polymers. The commonly applied SLS powder to date is polyamide 12 (PA 12). PA 12 or ccompounds of PA 12 (dry blends) are approximately 90 % of complete industrial consumption. The remaining small quantity is distributed on polyamide 11 (PA11) and some other `exotic' polymers (TPU, PEBA, P(E)EK). Industry is awaiting commodity polymers like polypropylene (PP) or polyethylene (PE) crucial to open new market segments. But several approaches launching those polymers failed. But what are the reasons for the difficulties in developing new SLS powders? The contribution is to answer this and highlights the combination of intrinsic and extrinsic polymer properties necessary to generate a polymer powder promising for SLS application. Particle shape, powder distribution, thermal, rheological and optical requirements must be considered and only a particularly controlled property combination leads to successful SLS implementation. Thermal behavior, particle shape and -distribution is discussed in detail, although the other properties can't be disregarded for providing new commercially successful SLS powder finally.

  6. Laser assisted direct manufacturing

    NASA Astrophysics Data System (ADS)

    Bertrand, Ph.; Smurov, I.

    2007-06-01

    Direct Laser Manufacturing (DLM) with coaxial powder injection (TRUMPF DMD 505 installation) was applied for fabrication of 3D objects from metallic and ceramic powder. One of the advantages of DLM is the possibility to build functionally graded objects in one-step manufacturing cycle by application of a 2-channel powder feeder. Several models with different types of material gradients (smooth, sharp, periodic) and multi-layered structures were manufactured from SS, stellite (Cobalt alloy), Cu and W alloys. Technology of Selective Laser Melting (SLM) was applied for manufacturing of net shaped objects from different powders (PHENIX PM-100 machine) : Inox 904L, Ni625, Cu/Sn, W and Zr02-Y2O3. Performance and limitations of SLM technology for fabrication of elements for chemical and mechanical industries are analysed. Two-component objects (Stainless steel /Cu - H13/CuNi) were fabricated in a two-step manufacturing cycle.

  7. Heat pipe manufacturing study

    NASA Technical Reports Server (NTRS)

    Edelstein, F.

    1974-01-01

    Heat pipe manufacturing methods are examined with the goal of establishing cost effective procedures that will ultimately result in cheaper more reliable heat pipes. Those methods which are commonly used by all heat pipe manufacturers have been considered, including: (1) envelope and wick cleaning, (2) end closure and welding, (3) mechanical verification, (4) evacuation and charging, (5) working fluid purity, and (6) charge tube pinch off. The study is limited to moderate temperature aluminum and stainless steel heat pipes with ammonia, Freon-21 and methanol working fluids. Review and evaluation of available manufacturers techniques and procedures together with the results of specific manufacturing oriented tests have yielded a set of recommended cost-effective specifications which can be used by all manufacturers.

  8. Advanced Polymer

    NASA Technical Reports Server (NTRS)

    1992-01-01

    In the mid-1980's, Langley developed a polyimide sulfone, combining desirable properties of two classes of polymers. Composites and other products made from polyimide sulfone can be used with solvents and corrosive fluids, are light weight, low cost and can be easily fabricated for a wide range of industrial uses. High Technology Systems, Inc. obtained a license for the polymer and was awarded a Small Business Innovation Research (SBIR) contract for development in a powder form. Although its principal use is as a matrix resin for composites, the material can also be used as a high temperature structural adhesive for aircraft structures and as a coating for protection from heat and radiation for electronic components.

  9. Phthalocyanine polymers

    NASA Technical Reports Server (NTRS)

    Achar, B. N.; Fohlen, G. M.; Parker, J. A. (Inventor)

    1985-01-01

    A method of forming 4,4',4'',4''' -tetraamino phthalocyanines involves reducing 4,4',4'',4''' -tetranitro phthalocyanines, polymerizing the metal tetraamino phthalocyanines with a tetracarboxylic dianhydride (preferably aromatic) or copolymerizing with a tetracarboxylic dianhydride and a diamine (preferably also aromatic) to produce amic acids which are then dehydrocyclized to imides. Thermally and oxidatively stable polymers result which form tough, flexible films, varnishes, adhesives, and fibers.

  10. Malaysian Polytechnic Development: A Cornerstone of Manufacturing Growth.

    ERIC Educational Resources Information Center

    Buskirk, Donald; Emshousen, Fred

    1996-01-01

    The Malaysian government has committed itself to become a manufacturing leader by 2020. To that end, they have developed educational strategies and prepared a cadre of instructors educated in a process that stresses integration of theory and application. (JOW)

  11. Periodic Polymers

    NASA Astrophysics Data System (ADS)

    Thomas, Edwin

    2013-03-01

    Periodic polymers can be made by self assembly, directed self assembly and by photolithography. Such materials provide a versatile platform for 1, 2 and 3D periodic nano-micro scale composites with either dielectric or impedance contrast or both, and these can serve for example, as photonic and or phononic crystals for electromagnetic and elastic waves as well as mechanical frames/trusses. Compared to electromagnetic waves, elastic waves are both less complex (longitudinal modes in fluids) and more complex (longitudinal, transverse in-plane and transverse out-of-plane modes in solids). Engineering of the dispersion relation between wave frequency w and wave vector, k enables the opening of band gaps in the density of modes and detailed shaping of w(k). Band gaps can be opened by Bragg scattering, anti-crossing of bands and discrete shape resonances. Current interest is in our group focuses using design - modeling, fabrication and measurement of polymer-based periodic materials for applications as tunable optics and control of phonon flow. Several examples will be described including the design of structures for multispectral band gaps for elastic waves to alter the phonon density of states, the creation of block polymer and bicontinuous metal-carbon nanoframes for structures that are robust against ballistic projectiles and quasi-crystalline solid/fluid structures that can steer shock waves.

  12. Structure of the polymer-solvent interface

    NASA Technical Reports Server (NTRS)

    Miles, Danny G., Jr.; Schmidt, James W.

    1990-01-01

    The first measurements of ellipticities from the liquid-liquid interface between polymer and solvent mixtures near their consolute points are reported. When scaled according to theory the ellipticities of high molecular weight polystyrene + solvent mixtures are consistent with those from simple, low molecular weight mixtures. The universal value of the scaled ellipticity is approximately 20 percent lower than that predicted by present theories.

  13. Performance of 18 polymers in aluminum citrate colloidal dispersion gels

    SciTech Connect

    Smith, J.E.

    1995-11-01

    Colloidal dispersion gels are made up of low concentrations of polymer and aluminum citrate in water. These gels, which are mixed as a homogeneous solution at the surface, provide a valuable tool for in-depth blockage of high permeability regions of rock in heterogeneous reservoirs. Performance of colloidal dispersion gels depends strongly on the type and quality of polymer used. This paper provides an overview of the performance of 18 different polymers in colloidal dispersion gels. 14 of the polymers were partially hydrolyzed polyacrylamides or AMPS polymers in dry crystalline form with varying degrees of hydrolysis and molecular weight. The group also includes one cationic polyacrylamide, one carboxymethyl cellulose, one partially hydrolyzed polyacrylamide in emulsion form and one polysaccharide in dry form. Gels were mixed with the polymers at two polymer concentrations, three polymer:aluminum ratios and in different concentrations of potassium chloride. The gels were quantitatively tested at 1, 7, 14 and 28 days after crosslinking using the transition pressure test, which is a screen flow resistance test. Of the six polymer types tested, only the dry partially hydrolyzed polyacrylamides and AMPS polymers formed colloidal dispersion gels. Gel strength generally increased with increasing anionic charge and molecular weight; however, the manner in which the polymer is manufactured and the impurities present in the polymer also play roles which are more significant than originally expected.

  14. 75 FR 104 - Manufacturing & Services' Sustainable Manufacturing Initiative; Update

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-04

    ... of Trade Policy Analysis, 202-482-2831. SUPPLEMENTARY INFORMATION: ITA's Manufacturing and Services... 18, 2009. Matthew Howard, Office of Trade Policy Analysis. BILLING CODE 3510-DR-P ... International Trade Administration Manufacturing & Services' Sustainable Manufacturing Initiative; Update...

  15. Flexible Manufacturing Systems: What's in It for the Manufacturer.

    ERIC Educational Resources Information Center

    Chowdhury, A. R.; Peckman, Donald C.

    1987-01-01

    The authors define the Flexible Manufacturing System and outline its history. They describe what the processing time includes and provide advantages and disadvantages of Flexible Manufacturing Systems compared to conventional manufacturing. (CH)

  16. Rapid small lot manufacturing

    SciTech Connect

    Harrigan, R.W.

    1998-05-09

    The direct connection of information, captured in forms such as CAD databases, to the factory floor is enabling a revolution in manufacturing. Rapid response to very dynamic market conditions is becoming the norm rather than the exception. In order to provide economical rapid fabrication of small numbers of variable products, one must design with manufacturing constraints in mind. In addition, flexible manufacturing systems must be programmed automatically to reduce the time for product change over in the factory and eliminate human errors. Sensor based machine control is needed to adapt idealized, model based machine programs to uncontrolled variables such as the condition of raw materials and fabrication tolerances.

  17. Polymer Energy Rechargeable System Battery Being Developed

    NASA Technical Reports Server (NTRS)

    Manzo, Michelle A.

    2003-01-01

    Long description. Illustrations of discotic liquid crystals, rod-coil polymers, lithium-ion conducting channel dilithium phthalocyanine (Li2Pc) from top and side, novel star polyethylene oxide structures, composite polyethylene oxide materials (showing polyethylene oxide + lithium salt, carbon atoms and oxygen atoms), homopolyrotaxanes, and diblock copolymers In fiscal year 2000, NASA established a program to develop the next generation, lithium-based, polymer electrolyte batteries for aerospace applications. The goal of this program, known as Polymer Energy Rechargeable Systems (PERS), is to develop a space-qualified, advanced battery system embodying polymer electrolyte and lithium-based electrode technologies and to establish world-class domestic manufacturing capabilities for advanced batteries with improved performance characteristics that address NASA s future aerospace battery requirements.

  18. Polymer Electronics: Power from Polymers

    SciTech Connect

    Venkataraman, D.; Russell, Thomas P.

    2012-06-19

    We review polymer-based electronics and photovoltaics to provide the reader with a sense of how the field has developed, where we stand at present, and what possibilities are looming in the future. Expertise in areas ranging from synthesis to morphology to device design was sought to achieve this end. While these reviews cannot be exhaustive, they do provide a snapshot of the field at present and give some sense of where the key impediments are.

  19. Novel Nanotube Manufacturing Streamlines Production

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Nanotubes have novel qualities that make them uniquely qualified for a plethora of uses, including applications in electronics, optics, and other scientific and industrial fields. The NASA process for creating these nanostructures involves using helium arc welding to vaporize an amorphous carbon rod and then form nanotubes by depositing the vapor onto a water-cooled carbon cathode, which then yields bundles, or ropes, of single-walled nanotubes at a rate of 2 grams per hour using a single setup. This eliminates costs associated with the use of metal catalysts, including the cost of product purification, resulting in a relatively inexpensive, high-quality, very pure end product. While managing to be less expensive, safer, and simpler, the process also increases the quality of the nanotubes. Goddard's Innovative Partnerships Program (IPP) Office promoted the technology, and in 2005, Boise-based Idaho Space Materials Inc. (ISM) was formed and applied for a nonexclusive license for the single-walled carbon nanotube (SWCNT) manufacturing technology. ISM commercialized its products, and the inexpensive, robust nanotubes are now in the hands of the scientists who will create the next generation of composite polymers, metals, and ceramics that will impact the way we live. In fact, researchers are examining ways for these newfound materials to be used in the manufacture of transistors and fuel cells, large screen televisions, ultra-sensitive sensors, high-resolution atomic force microscopy probes, supercapacitors, transparent conducting films, drug carriers, catalysts, and advanced composite materials, to name just a few of the myriad technologies to benefit.

  20. Precision manufacturing of compact disc master stampers

    SciTech Connect

    Bifano, T.; Caggiano, H.; Bierden, P.

    1996-12-31

    The authors have developed a new manufacturing process for compact disc master stamper production. Stamper is an industry term for the mold used to replicate polymer CDs in an injection molding device. The stamper surface contains a negative image of the CD`s >1 billion features, each measuring 0.5 {mu}m wide, 1-3{mu}m long, and 150 nm tall. These features are embossed in a spiral pattern on the 138 mm diameter stamper substrate. In conventional mastering, nickel sub-master stampers are generated by electroforming from a glass master with a masked photoresist layer. In the new process, called Precision Stamper Manufacturing (PSM), sub-master stampers are not required - the ceramic master is used directly as a stamper for injection molding. The technology uses precision manufacturing to improve productivity, reduce hazardous waste, and reduce costs in production of master stampers. All critical process steps have been proven feasible in the research reported here. More than 120 minutes of conventional manufacturing processes are replaced by about 20 minutes of precision machining processes, with improved precision in the final component. Another benefit of PSM is that it eliminates most process steps that produce hazardous wastes. Objectives of the experimental research have been to verify feasibility of the method, and to manufacture a prototype CD stamper. Over the past year, we have demonstrated feasibility of all process steps in the new method, and results will be presented. Also, we uncovered and quantified several important limitations for each process step, and combined the individual steps into a manufacturing cycle through which a full-scale working stamper prototype was made. These experiments made use of available facilities at two major equipment suppliers for the CD, an ion machining equipment, and a national research facility, in addition to facilities at Boston University and Prism Corporation.

  1. Polymer-composite ball lightning.

    PubMed

    Bychkov, V L

    2002-01-15

    Investigations into the state of ball lightning (BL) have been made, and both theory and experiments, related to so-called "polymer-composite" ball lightning, are presented. The properties of such a polymeric BL have been described and are that of a long-lived object capable of storing high energy. Results of experiments, starting with polymeric components in erosive gas discharge experiments, are described and discussed. The model of BL as a highly charged polymer-dielectric structure is described. According to this model BL appears as the result of the aggregation of natural polymers, such as lignin and cellulose, soot, polymeric silica and other natural dust particles. Its ability to glow is explained by the appearance over its perimeter of gas discharges near the highly charged BL surface, and electrical breakdown of some regions on the surface, consisting of polymerized and aggregated threads. PMID:16210170

  2. The Manufacturing Game

    ERIC Educational Resources Information Center

    Fenn, Margaret

    1972-01-01

    Article describes management training through playing a game which involves the creation and operation of a business organization devoted to manufacturing and sales. Precise details on setting up the game are given. (Author/PD)

  3. Computers in Manufacturing.

    ERIC Educational Resources Information Center

    Hudson, C. A.

    1982-01-01

    Advances in factory computerization (computer-aided design and computer-aided manufacturing) are reviewed, including discussions of robotics, human factors engineering, and the sociological impact of automation. (JN)

  4. Agile manufacturing concept

    NASA Astrophysics Data System (ADS)

    Goldman, Steven L.

    1994-03-01

    The initial conceptualization of agile manufacturing was the result of a 1991 study -- chaired by Lehigh Professor Roger N. Nagel and California-based entrepreneur Rick Dove, President of Paradigm Shifts, International -- of what it would take for U.S. industry to regain global manufacturing competitiveness by the early twenty-first century. This industry-led study, reviewed by senior management at over 100 companies before its release, concluded that incremental improvement of the current system of manufacturing would not be enough to be competitive in today's global marketplace. Computer-based information and production technologies that were becoming available to industry opened up the possibility of an altogether new system of manufacturing, one that would be characterized by a distinctive integration of people and technologies; of management and labor; of customers, producers, suppliers, and society.

  5. Manufacturing development of visor for binocular helmet mounted display

    NASA Astrophysics Data System (ADS)

    Krevor, David; Edwards, Timothy; Larkin, Eric; Skubon, John; Speirs, Robert; Sowden, Tom

    2007-09-01

    The HMD (Helmet Mounted Display) visor is a sophisticated article. It is both the optical combiner for the display and personal protective equipment for the pilot. The visor must have dimensional and optical tolerances commensurate with precision optics; and mechanical properties sufficient for a ballistic shield. Optimized processes and tooling are necessary in order to manufacture a functional visor. This paper describes the manufacturing development of the visor for the Joint Strike Fighter (JSF) HMD. The analytical and experimental basis for the tool and manufacturing process development are described; as well as the metrological and testing methods to verify the visor design and function. The requirements for the F-35 JSF visor are a generation beyond those for the HMD visor which currently flies on the F-15, F-16 and F/A-18. The need for greater precision is manifest in the requirements for the tooling and molding process for the visor. The visor is injection-molded optical polycarbonate, selected for its combination of optical, mechanical and environmental properties. Proper design and manufacture of the tool - the mold - is essential. Design of the manufacturing tooling is an iterative process between visor design, mold design, mechanical modeling and polymer-flow modeling. Iterative design and manufacture enable the mold designer to define a polymer shrinkage factor more precise than derived from modeling or recommended by the resin supplier.

  6. Holonic Manufacturing Paint Shop

    NASA Astrophysics Data System (ADS)

    Lind, Morten; Roulet-Dubonnet, Olivier; Nyen, Per Åge; Gellein, Lars Tore; Lien, Terje; Skavhaug, Amund

    In pursuit of flexibility and agility within discrete manufacturing, the surrounding logistics and handling processes of a paint shop is under construction as a laboratory prototype application. Holonic Manufacturing seems to be a promising strategic paradigm and architecture to use for a system characterised by production logistics and control. This paper describes the physical devices to be used; the desired functionality; and the basic logic control designed. Additionally, the ideas for holonification based on the already designed logic control is presented.

  7. Polymer escape from a confining potential

    SciTech Connect

    Mökkönen, Harri; Ikonen, Timo; Jónsson, Hannes; Ala-Nissila, Tapio

    2014-02-07

    The rate of escape of polymers from a two-dimensionally confining potential well has been evaluated using self-avoiding as well as ideal chain representations of varying length, up to 80 beads. Long timescale Langevin trajectories were calculated using the path integral hyperdynamics method to evaluate the escape rate. A minimum is found in the rate for self-avoiding polymers of intermediate length while the escape rate decreases monotonically with polymer length for ideal polymers. The increase in the rate for long, self-avoiding polymers is ascribed to crowding in the potential well which reduces the free energy escape barrier. An effective potential curve obtained using the centroid as an independent variable was evaluated by thermodynamic averaging and Kramers rate theory then applied to estimate the escape rate. While the qualitative features are well reproduced by this approach, it significantly overestimates the rate, especially for the longer polymers. The reason for this is illustrated by constructing a two-dimensional effective energy surface using the radius of gyration as well as the centroid as controlled variables. This shows that the description of a transition state dividing surface using only the centroid fails to confine the system to the region corresponding to the free energy barrier and this problem becomes more pronounced the longer the polymer is. A proper definition of a transition state for polymer escape needs to take into account the shape as well as the location of the polymer.

  8. Polymer escape from a confining potential

    NASA Astrophysics Data System (ADS)

    Mökkönen, Harri; Ikonen, Timo; Jónsson, Hannes; Ala-Nissila, Tapio

    2014-02-01

    The rate of escape of polymers from a two-dimensionally confining potential well has been evaluated using self-avoiding as well as ideal chain representations of varying length, up to 80 beads. Long timescale Langevin trajectories were calculated using the path integral hyperdynamics method to evaluate the escape rate. A minimum is found in the rate for self-avoiding polymers of intermediate length while the escape rate decreases monotonically with polymer length for ideal polymers. The increase in the rate for long, self-avoiding polymers is ascribed to crowding in the potential well which reduces the free energy escape barrier. An effective potential curve obtained using the centroid as an independent variable was evaluated by thermodynamic averaging and Kramers rate theory then applied to estimate the escape rate. While the qualitative features are well reproduced by this approach, it significantly overestimates the rate, especially for the longer polymers. The reason for this is illustrated by constructing a two-dimensional effective energy surface using the radius of gyration as well as the centroid as controlled variables. This shows that the description of a transition state dividing surface using only the centroid fails to confine the system to the region corresponding to the free energy barrier and this problem becomes more pronounced the longer the polymer is. A proper definition of a transition state for polymer escape needs to take into account the shape as well as the location of the polymer.

  9. Manufacturing information system

    NASA Astrophysics Data System (ADS)

    Allen, D. K.; Smith, P. R.; Smart, M. J.

    1983-12-01

    The size and cost of manufacturing equipment has made it extremely difficult to perform realistic modeling and simulation of the manufacturing process in university research laboratories. Likewise the size and cost factors, coupled with many uncontrolled variables of the production situation has even made it difficult to perform adequate manufacturing research in the industrial setting. Only the largest companies can afford manufacturing research laboratories; research results are often held proprietary and seldom find their way into the university classroom to aid in education and training of new manufacturing engineers. It is the purpose for this research to continue the development of miniature prototype equipment suitable for use in an integrated CAD/CAM Laboratory. The equipment being developed is capable of actually performing production operations (e.g. drilling, milling, turning, punching, etc.) on metallic and non-metallic workpieces. The integrated CAD/CAM Mini-Lab is integrating high resolution, computer graphics, parametric design, parametric N/C parts programmings, CNC machine control, automated storage and retrieval, with robotics materials handling. The availability of miniature CAD/CAM laboratory equipment will provide the basis for intensive laboratory research on manufacturing information systems.

  10. Printed polymer photonic devices for optical interconnect systems

    NASA Astrophysics Data System (ADS)

    Subbaraman, Harish; Pan, Zeyu; Zhang, Cheng; Li, Qiaochu; Guo, L. J.; Chen, Ray T.

    2016-03-01

    Polymer photonic device fabrication usually relies on the utilization of clean-room processes, including photolithography, e-beam lithography, reactive ion etching (RIE) and lift-off methods etc, which are expensive and are limited to areas as large as a wafer. Utilizing a novel and a scalable printing process involving ink-jet printing and imprinting, we have fabricated polymer based photonic interconnect components, such as electro-optic polymer based modulators and ring resonator switches, and thermo-optic polymer switch based delay networks and demonstrated their operation. Specifically, a modulator operating at 15MHz and a 2-bit delay network providing up to 35.4ps are presented. In this paper, we also discuss the manufacturing challenges that need to be overcome in order to make roll-to-roll manufacturing practically viable. We discuss a few manufacturing challenges, such as inspection and quality control, registration, and web control, that need to be overcome in order to realize true implementation of roll-to-roll manufacturing of flexible polymer photonic systems. We have overcome these challenges, and currently utilizing our inhouse developed hardware and software tools, <10μm alignment accuracy at a 5m/min is demonstrated. Such a scalable roll-to-roll manufacturing scheme will enable the development of unique optoelectronic devices which can be used in a myriad of different applications, including communication, sensing, medicine, security, imaging, energy, lighting etc.

  11. Multicomponent Thermodynamics of Strain-Induced Polymer Crystallization.

    PubMed

    Zha, Liyun; Wu, Yixian; Hu, Wenbing

    2016-07-14

    We developed a linear combination of two Flory's melting-point theories, one for stretched and the other for solution polymers, to predict the melting point of stretched solution polymers. The dependences of the melting strains on varying temperatures, polymer volume fractions, and solvent qualities were verified by the onset strains of crystallization in our dynamic Monte Carlo simulations of stretched solution polymers under a constant strain rate. In addition, owing to phase separation before crystallization in a poor solvent, calibration of polymer concentration to the polymer-rich phase appears necessary for the verification. Our results set up a preliminary thermodynamic background for the investigation of the multicomponent effect on strain-induced crystallization of polymers in rubbers and gels as well as on shear-induced crystallization of polymers in solutions and blends. PMID:27337066

  12. Three-body interactions in polymer nanocomposites.

    SciTech Connect

    Yethiraj, Arun; Frischknecht, Amalie Lucile

    2010-04-01

    We use the modified iSAFT density functional theory (DFT) to calculate interactions among nanoparticles immersed in a polymer melt. Because a polymer can simultaneously interact with more than two nanoparticles, three-body interactions are important in this system. We treat the nanoparticles as spherical surfaces, and solve for the polymer densities around the nanoparticles in three dimensions. The polymer is modeled as a freely-jointed chain of spherical sites, and all interactions are repulsive. The potential of mean force (PMF) between two nanoparticles displays a minimum at contact due to the depletion effect. The PMF calculated from the DFT agrees nearly quantitatively with that calculated from self-consistent PRISM theory. From the DFT we find that the three-body free energy is significantly different in magnitude than the effective three-body free energy derived from the two-particle PMF.

  13. Polymer-induced compression of biological hydrogels

    NASA Astrophysics Data System (ADS)

    Datta, Sujit; Preska Steinberg, Asher; Ismagilov, Rustem

    Hydrogels - such as mucus, blood clots, and the extracellular matrix - provide critical functions in biological systems. However, little is known about how their structure is influenced by many of the polymeric materials they come into contact with regularly. Here, we focus on one critically important biological hydrogel: colonic mucus. While several biological processes are thought to potentially regulate the mucus hydrogel structure, the polymeric composition of the gut environment has been ignored. We use Flory-Huggins solution theory to characterize polymer-mucus interactions. We find that gut polymers, including those small enough to penetrate the mucus hydrogel, can in fact alter mucus structure, changing its equilibrium degree of swelling and forcing it to compress. The extent of compression increases with increasing polymer concentration and size. We use experiments on mice to verify these predictions with common dietary and therapeutic gut polymers. Our results provide a foundation for investigating similar, previously overlooked, polymer-induced effects in other biological hydrogels.

  14. Planar dipolar polymer brush: field theoretical investigations

    NASA Astrophysics Data System (ADS)

    Mahalik, Jyoti; Kumar, Rajeev; Sumpter, Bobby

    2015-03-01

    Physical properties of polymer brushes bearing monomers with permanent dipole moments and immersed in a polar solvent are investigated using self-consistent field theory (SCFT). It is found that mismatch between the permanent dipole moments of the monomer and the solvent plays a significant role in determining the height of the polymer brush. Sign as well as magnitude of the mismatch determines the extent of collapse of the polymer brush. The mismatch in the dipole moments also affects the force-distance relations and interpenetration of polymers in opposing planar brushes. In particular, an attractive force between the opposing dipolar brushes is predicted for stronger mismatch parameter. Furthermore, effects of added monovalent salt on the structure of dipolar brushes will also be presented. This investigation highlights the significance of dipolar interactions in affecting the physical properties of polymer brushes. Csmd division, Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37831, USA.

  15. Study and modeling of the ironing process on a multi-layered polymer coated low-carbon steel

    NASA Astrophysics Data System (ADS)

    Selles Canto, Miguel Angel

    is defective either by shaving or detachment of the upper layer of polymer. Arcelor-Mittal provided two similar materials, both consisting of a steel substrate coated by three polymer layers. They have been tested according to the theory of design of experiments, in order to determine the feasibility of their use in the manufacture of cans. An ironing process simulator has been designed and constructed that works under conditions similar to those in industry. Validation of the theoretically-generated models has been possible thanks to the use of the ironing simulator, providing results that show good agreement between the theoretical and real behaviors. Finally, after obtaining the different results from the theoretical and experimental work, they have been analyzed to determine the feasibility of using these materials for the manufacture of metal containers that need the ironing process. The information obtained from this analysis shows that, under certain conditions, it is perfectly possible to use one of these two materials for the proposed purpose, making the proposed goals possible. The die angle is the most critical variable among all the ones studied, and when it takes values greater than 7°, some of the coating polymer layers are damaged.

  16. Interpretations of Polymer-Polymer Miscibility.

    ERIC Educational Resources Information Center

    Olabisi, Olagoke

    1981-01-01

    Discusses various aspects of polymeric mixtures, mixtures of structurally different homopolymers, copolymers, terpolymers, and the like. Defines concepts of polymer-polymer miscibility from practical and theoretical viewpoints, and ways of predicting such miscibility. (JN)

  17. Blood Clotting Inspired Polymer Physics

    NASA Astrophysics Data System (ADS)

    Sing, Charles Edward

    The blood clotting process is one of the human body's masterpieces in targeted molecular manipulation, as it requires the activation of the clotting cascade at a specific place and a specific time. Recent research in the biological sciences have discovered that one of the protein molecules involved in the initial stages of the clotting response, von Willebrand Factor (vWF), exhibits counterintuitive and technologically useful properties that are driven in part by the physical environment in the bloodstream at the site of a wound. In this thesis, we take inspiration from initial observations of the vWF in experiments, and aim to describe the behaviors observed in this process within the context of polymer physics. By understanding these physical principles, we hope to harness nature's ability to both direct molecules in both spatial and conformational coordinates. This thesis is presented in three complementary sections. After an initial introduction describing the systems of interest, we first describe the behavior of collapsed Lennard-Jones polymers in the presence of an infinite medium. It has been shown that simple bead-spring homopolymer models describe vWF quite well in vitro. We build upon this previous work to first describe the behavior of a collapsed homopolymer in an elongational fluid flow. Through a nucleation-protrusion mechanism, scaling relationships can be developed to provide a clear picture of a first-order globule-stretch transition and its ramifications in dilute-solution rheology. The implications of this behavior and its relation to the current literature provides qualitative explanations for the physiological process of vasoconstriction. In an effort to generalize these observations, we present an entire theory on the behavior of polymer globules under influence of any local fluid flow. Finally, we investigate the internal dynamics of these globules by probing their pulling response in an analogous fashion to force spectroscopy. We elucidate

  18. Multilevel clustering fault model for IC manufacture

    NASA Astrophysics Data System (ADS)

    Bogdanov, Yu. I.; Bogdanova, N. A.; Rudnev, A. V.

    2004-05-01

    A hierarchical approach to the construction of compound distributions for process-induced faults in IC manufacture is proposed. Within this framework, the negative binomial distribution is treated as level-1 models. The hierarchical approach to fault distribution offers an integrated picture of how fault density varies from region to region within a wafer, from wafer to wafer within a batch, and so on. A theory of compound-distribution hierarchies is developed by means of generating functions. A study of correlations, which naturally appears in microelectronics due to the batch character of IC manufacture, is proposed. Taking these correlations into account is of significant importance for developing procedures for statistical quality control in IC manufacture. With respect to applications, hierarchies of yield means and yield probability-density functions are considered.

  19. National Center for Manufacturing Sciences: Environmentally conscious manufacturing

    NASA Technical Reports Server (NTRS)

    Vinton, Clare

    1995-01-01

    The purpose of this presentation is to share the results and some of the thinking of the Environmentally Conscious Manufacturing - Strategic Initiative Group (ECM-SIG) at the National Center for Manufacturing Sciences (NCMS). NCMS is a consortium of more than 185 North American Manufacturing organizations comprised of about 75 percent for profit manufacturing companies and about 25 percent nonprofit organizations that support manufacturing activities. NCMS conducts collaborative R&D programs designed to improve global competitiveness of its members and other North American manufacturers to address common issues that are important to manufacturing industries. NCMS is an industry driven organization whose agenda is established by industry with input from appropriate government agencies.

  20. Technology and Development of Self-Reinforced Polymer Composites

    NASA Astrophysics Data System (ADS)

    Alcock, Ben; Peijs, Ton

    In recent years there has been an increasing amount of interest, both commercially and scientifically, in the emerging field of "self-reinforced polymer composites". These materials, which are sometimes also referred to as "single polymer composites", or "all-polymer composites", were first conceived in the 1970s, and are now beginning to appear in a range of commercial products. While high mechanical performance polymer fibres or tapes are an obvious precursor for composite development, various different technologies have been developed to consolidate these into two- or three-dimensional structures. This paper presents a review of the various processing techniques that have been reported in the literature for the manufacture of self-reinforced polymer composites from fibres or tapes of different polymers, and so exploit the fibre or tape performance in a commercial material or product.

  1. Solid polymer electrolyte composite membrane comprising laser micromachined porous support

    DOEpatents

    Liu, Han; LaConti, Anthony B.; Mittelsteadt, Cortney K.; McCallum, Thomas J.

    2011-01-11

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 5 microns, are made by laser micromachining and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

  2. Mobile monolithic polymer elements for flow control in microfluidic devices

    DOEpatents

    Hasselbrink, Jr., Ernest F.; Rehm, Jason E.; Shepodd, Timothy J.

    2004-08-31

    A cast-in-place and lithographically shaped mobile, monolithic polymer element for fluid flow control in microfluidic devices and method of manufacture. Microfluid flow control devices, or microvalves that provide for control of fluid or ionic current flow can be made incorporating a cast-in-place, mobile monolithic polymer element, disposed within a microchannel, and driven by either fluid or gas pressure against a retaining or sealing surface. The polymer elements are made by the application of lithographic methods to monomer mixtures formulated in such a way that the polymer will not bond to microchannel walls. The polymer elements can seal against pressures greater than 5000 psi, and have a response time on the order of milliseconds. By the use of energetic radiation it is possible to depolymerize selected regions of the polymer element to form shapes that cannot be produced by conventional lithographic patterning and would be impossible to machine.

  3. Mobile Monolith Polymer Elements For Flow Control In Microfluidic Systems

    DOEpatents

    Hasselbrink, Jr., Ernest F.; Rehm, Jason E.; Shepodd, Timothy J.; Kirby, Brian J.

    2006-01-24

    A cast-in-place and lithographically shaped mobile, monolithic polymer element for fluid flow control in microfluidic devices and method of manufacture. Microfluid flow control devices, or microvalves that provide for control of fluid or ionic current flow can be made incorporating a cast-in-place, mobile monolithic polymer element, disposed within a microchannel, and driven by fluid pressure (either liquid or gas) against a retaining or sealing surface. The polymer elements are made by the application of lithographic methods to monomer mixtures formulated in such a way that the polymer will not bond to microchannel walls. The polymer elements can seal against pressures greater than 5000 psi, and have a response time on the order of milliseconds. By the use of energetic radiation it is possible to depolymerize selected regions of the polymer element to form shapes that cannot be produced by conventional lithographic patterning and would be impossible to machine.

  4. Mobile monolithic polymer elements for flow control in microfluidic devices

    DOEpatents

    Hasselbrink, Jr., Ernest F.; Rehm, Jason E.; Shepodd, Timothy J.; Kirby, Brian J.

    2005-11-11

    A cast-in-place and lithographically shaped mobile, monolithic polymer element for fluid flow control in microfluidic devices and method of manufacture. Microfluid flow control devices, or microvalves that provide for control of fluid or ionic current flow can be made incorporating a cast-in-place, mobile monolithic polymer element, disposed within a microchannel, and driven by fluid pressure (either liquid or gas) against a retaining or sealing surface. The polymer elements are made by the application of lithographic methods to monomer mixtures formulated in such a way that the polymer will not bond to microchannel walls. The polymer elements can seal against pressures greater than 5000 psi, and have a response time on the order of milliseconds. By the use of energetic radiation it is possible to depolymerize selected regions of the polymer element to form shapes that cannot be produced by conventional lithographic patterning and would be impossible to machine.

  5. Nanoimprint lithography for functional polymer patterning

    NASA Astrophysics Data System (ADS)

    Cui, Dehu

    2011-07-01

    Organic semiconductors have generated huge interested in recent years for low-cost and flexible electronics. Current and future device applications for semiconducting polymers include light-emitting diodes, thin-film transistors, photovoltaic cells, photodetectors, lasers, and memories. The performance of conjugated polymer devices depends on two major factors: the chain conformation in polymer film and the device architecture. Highly ordered chain structure usually leads to much improved performance by enhancing interchain interaction to facilitate carrier transport. The goal of this research is to improve the performance of organic devices with the nanoimprint lithography. The work begins with the controlling of polymer chain orientation in patterned nanostructures through nanoimprint mold design and process parameter manipulation, and studying the effect of chain ordering on material properties. Then, step-and-repeat thermal nanoimprint technique for large-scale continuous manufacturing of conjugated polymer nanostructures is developed. After that, Systematic investigation of polymer chain configuration by Raman spectroscopy is carried out to understand how nanoimprint process parameters, such as mold pattern size, temperature, and polymer molecular weight, affects polymer chain configuration. The results indicate that chain orientation in nanoimprinted polymer micro- and nanostructures is highly related to the nanoimprint temperature and the dimensions of the mold structures. The ability to create nanoscale polymer micro- and nanostructures and manipulate their internal chain conformation establishes an original experimental platform that enables studying the properties of functional polymers at the micro- and nanoscale and understanding their fundamental structure-property relationships. In addition to the impact on basic research, the techniques developed in this work are important in applied research and development. Large-area conjugated polymer micro- and

  6. Manufacture of DPFC-DMS polymer in the SKG range

    NASA Technical Reports Server (NTRS)

    Hughes, B. M.; Owen, D. R.; Futrell, J. H.

    1979-01-01

    BPFC-DMS block copolymers were synthesized on a pre-pilot scale (i.e., to 5 Kg lots) and subsequently fabricated into clear, colorless films. Details of the synthesis procedures, property determinations, and film casting techniques are presented. Solubility, viscosity and molecular weight characteristics of the resulting product are reported.

  7. Crystallization analysis for fiber/polymer composites

    NASA Astrophysics Data System (ADS)

    Raimo, Maria

    2016-05-01

    The peculiar nucleation behavior of low thermal conductivity polymer matrixes and the particular morphologies around fibers found in several composites, invalidate some assumptions invoked in the general description of the solidification kinetics of polycrystalline substances. The model of solidification universally adopted for polycrystalline substances, originally developed for metals, needs to be adapted also to account for large differences between polymers and fibers in thermoplastic composites. The extension of the classical phase transitions theory to fiber/polymer composites, in view of their specific thermal properties, allows to achieve reliable information on crystallization behavior and microstructure inside composites.

  8. Conformational properties of an adsorbed charged polymer.

    PubMed

    Cheng, Chi-Ho; Lai, Pik-Yin

    2005-06-01

    The behavior of a strongly charged polymer adsorbed on an oppositely charged surface of a low-dielectric constant is formulated by the functional integral method. By separating the translational, conformational, and fluctuational degrees of freedom, the scaling behaviors for both the height of the polymer and the thickness of the diffusion layer are determined. Unlike the results predicted by scaling theory, we identified the continuous crossover from the weak compression to the compression regime. All the analytical results are found to be consistent with Monte Carlo simulations. Finally, an alternative (operational) definition of a charged polymer adsorption is proposed. PMID:16089715

  9. Additive Manufacturing Infrared Inspection

    NASA Technical Reports Server (NTRS)

    Gaddy, Darrell

    2014-01-01

    Additive manufacturing is a rapid prototyping technology that allows parts to be built in a series of thin layers from plastic, ceramics, and metallics. Metallic additive manufacturing is an emerging form of rapid prototyping that allows complex structures to be built using various metallic powders. Significant time and cost savings have also been observed using the metallic additive manufacturing compared with traditional techniques. Development of the metallic additive manufacturing technology has advanced significantly over the last decade, although many of the techniques to inspect parts made from these processes have not advanced significantly or have limitations. Several external geometry inspection techniques exist such as Coordinate Measurement Machines (CMM), Laser Scanners, Structured Light Scanning Systems, or even traditional calipers and gages. All of the aforementioned techniques are limited to external geometry and contours or must use a contact probe to inspect limited internal dimensions. This presentation will document the development of a process for real-time dimensional inspection technique and digital quality record of the additive manufacturing process using Infrared camera imaging and processing techniques.

  10. Expected and unexpected achievements and trends in radiation processing of polymers

    NASA Astrophysics Data System (ADS)

    Czvikovszky, T.

    2003-06-01

    The last four decades produced exponential development in the polymer processing. Radiation processing—initiated also about 40 years ago—yielded a similar pathway of development in the beginning, mostly in the radiation crosslinking of polymers and in the radiation sterilization of polymer products. There are some unexpected results in the developments of the radiation chemistry of polymers utilized well in the polymer processing today. The most dynamical developments of the microelectronics in our days are based on the efficient utilization of radiation-crosslinkable negative photoresist polymers and the radiation degradable positive photoresist polymers. Rapid prototyping and rapid tooling are indispensable methods in the continuously renewing manufacturing technologies of metal and plastic parts for almost all the industrial branches. Polymer composite manufacturing is also profited in many ways from the experiences of radiation technology. Compatibilization through radiation-reactive monomers and oligomers is attacking two great fields of the future polymer processing. Recycling of commingled polymer wastes, and manufacturing new type of alloys of different synthetic as well as natural polymers are requiring well-engineered interface, which can be achieved by radiation processing in a technically feasible and economically viable way.

  11. Ultrasonic wave techniques and characterization of filled elastomers and biodegradable polymers

    NASA Astrophysics Data System (ADS)

    Wu, Hsueh-Chang

    Ultrasonic wave technique is an excellent method for non-destructive testing and for the monitoring of polymer curing, fatigue damage and polymer transition. It is also a potentially effective tool to be applied in the characterization of high frequency viscoelastic properties of polymers. This research represents the effort to improve and further develop ultrasonic wave techniques and extend its applications to new material evaluation areas. The work is presented as followings: In chapter 1, the fundamental wave propagation theories and characterization of the viscoelastic properties of materials by acoustic parameters were briefly reviewed. In chapter 2, the effects of carbon black filler on the elastomers were studied by the longitudinal wave pulse-echo technique. It is found that the enhanced pulse-echo technique is able to characterize the effects of polymer base, filler loading level, type as well as temperature, on the acoustic properties of filled elastomers. In chapter 3, the application of longitudinal wave pulse-echo technique was extended to the monitoring of the degradation process of biodegradable polymers: poly (glycolic acid)(PGA), poly (lactic acid) (PLA) and their copolymer-poly(d,l-lactide-co-glycolide) (PDLLG). It shows that the pulse-echo technique is able to differentiate the effects of polymer structure and preparation method on the degradation behavior of biopolymers. In chapter 4, the Young's modulus, shear modulus, bulk modulus and Poisson ratio of carbon black filled elastomers were determined by the longitudinal wave pulse-echo method and the shear wave through-transmission method. The effects of polymer base, filler loading and dispersion on the elastomers were also studied by the calculated elastic constants. In chapter 5, the effects of carbon black filler on the elastomers were studied by an innovative calibrated longitudinal and shear wave surface impedance technique. The results show that the effects of polymer base, filler loading

  12. Environmentally sound manufacturing

    NASA Technical Reports Server (NTRS)

    Caddy, Larry A.; Bowman, Ross; Richards, Rex A.

    1994-01-01

    The NASA/Thiokol/industry team has developed and started implementation of an environmentally sound manufacturing plan for the continued production of solid rocket motors. They have worked with other industry representatives and the U.S. Environmental Protection Agency to prepare a comprehensive plan to eliminate all ozone depleting chemicals from manufacturing processes and to reduce the use of other hazardous materials used to produce the space shuttle reusable solid rocket motors. The team used a classical approach for problem solving combined with a creative synthesis of new approaches to attack this problem. As our ability to gather data on the state of the Earth's environmental health increases, environmentally sound manufacturing must become an integral part of the business decision making process.

  13. Environmentally sound manufacturing

    NASA Astrophysics Data System (ADS)

    Caddy, Larry A.; Bowman, Ross; Richards, Rex A.

    The NASA/Thiokol/industry team has developed and started implementation of an environmentally sound manufacturing plan for the continued production of solid rocket motors. They have worked with other industry representatives and the U.S. Environmental Protection Agency to prepare a comprehensive plan to eliminate all ozone depleting chemicals from manufacturing processes and to reduce the use of other hazardous materials used to produce the space shuttle reusable solid rocket motors. The team used a classical approach for problem solving combined with a creative synthesis of new approaches to attack this problem. As our ability to gather data on the state of the Earth's environmental health increases, environmentally sound manufacturing must become an integral part of the business decision making process.

  14. 78 FR 67117 - Manufacturing Council

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-08

    ... International Trade Administration Manufacturing Council AGENCY: International Trade Administration, U.S. Department of Commerce. ACTION: Notice of an Opportunity to Apply for Membership on the Manufacturing Council.... manufacturing industry to fill five vacant positions on the Manufacturing Council (Council). The purpose of...

  15. Onset of polymer entanglement

    SciTech Connect

    Chitanvis, S.M.

    1998-09-01

    We have developed a theory of polymer entanglement using an extended Cahn-Hilliard functional with two extra terms. One is a nonlocal attractive term, operating over mesoscales, which is interpreted as giving rise to entanglement, and the other is a local repulsive term indicative of excluded volume interactions. This functional can be derived using notions from gauge theory. We go beyond the Gaussian approximation, to the one-loop level, to show that the system exhibits a crossover to a state of entanglement as the average chain length between points of entanglement decreases. This crossover is marked by {ital critical} slowing down, as the effective diffusion constant goes to zero. We have also computed the tensile modulus of the system, and we find a corresponding crossover to a regime of high modulus. The single parameter in our theory is obtained by fitting to available experimental data on polystyrene melts of various chain lengths. Extrapolation of this fit yields a model for the crossover to entanglement. The need for additional experiments detailing the crossover to the entangled state is pointed out. {copyright} {ital 1998} {ital The American Physical Society}

  16. Capabilities Of Micro Powder Injection Molding For Microparts Manufacturing

    NASA Astrophysics Data System (ADS)

    Kong, X.; Barriere, T.; Gelin, J. C.

    2011-01-01

    The Micro-PIM processing technology satisfies the increasing demand in terms of smaller parts and miniaturization. Research works in this area have been carried out at FEMTO-ST Institute by performing the injection molding with 316L stainless steel fine powders and polymer binders. Several formulations with different proportion of powders and binders as well various polymers have been tested, and then a well adapted one has been selected. The process to select the well adapted formulation and the rheological characteristics of the feedstock realized according with the selected formulation are also detailed. Several test specimens have been successfully manufactured.

  17. From Commodity Polymers to Functional Polymers

    PubMed Central

    Xiang, Tao; Wang, Ling-Ren; Ma, Lang; Han, Zhi-Yuan; Wang, Rui; Cheng, Chong; Xia, Yi; Qin, Hui; Zhao, Chang-Sheng

    2014-01-01

    Functional polymers bear specified chemical groups, and have specified physical, chemical, biological, pharmacological, or other uses. To adjust the properties while keeping material usage low, a method for direct synthesis of functional polymers is indispensable. Here we show that various functional polymers can be synthesized by in situ cross-linked polymerization/copolymerization. We demonstrate that the polymers synthesized by the facile method using different functional monomers own outstanding pH-sensitivity and pH-reversibility, antifouling property, antibacterial, and anticoagulant property. Our study opens a route for the functionalization of commodity polymers, which lead to important advances in polymeric materials applications. PMID:24710333

  18. Normoxic polymer gels: are they magic?

    NASA Astrophysics Data System (ADS)

    Amin, M. N.; Bonnett, D. E.; Horsfield, M. A.

    2004-01-01

    In the last few years there has been considerable interest in the use of polymer gels to measure complex dose distributions in radiotherapy. Despite considerable advantages they are still not widely used in clinical situations. This is due primarily to the difficulty in manufacture, particularly the need to exclude oxygen both from the gel and the manufacturing process, the limited number of suitable phantom materials and the need for easy access to an MRI facility. The purpose of this paper is to report on an investigation of the basic properties of MAGIC gels namely: linearity of response, effects of temperature and stability.

  19. ATS materials/manufacturing

    SciTech Connect

    Karnitz, M.A.; Wright, I.G.; Ferber, M.K.

    1997-11-01

    The Materials/Manufacturing Technology subelement is a part of the base technology portion of the Advanced Turbine Systems (ATS) Program. The work in this subelement is being performed predominantly by industry with assistance from national laboratories and universities. The projects in this subelement are aimed toward hastening the incorporation of new materials and components in gas turbines. Work is currently ongoing on thermal barrier coatings (TBCs), the scale-up of single crystal airfoil manufacturing technologies, materials characterization, and technology information exchange. This paper presents highlights of the activities during the past year. 12 refs., 24 figs., 4 tabs.

  20. Energy consumption in manufacturing

    NASA Astrophysics Data System (ADS)

    Schmid, S. R.

    2012-04-01

    Energy sources, in the form of coal, oil, natural gas, solar or nuclear power, are global commodities, and as demand is projected to rise in the coming decades, so will costs. As such, an understanding of the energy needs of manufacturing processes and the ability to reduce the energy and carbon footprints are essential for sustainability reasons. Energy source effects are quantified in a number of measures. Models of energy needs by manufacturing processes are then examined, along with models incorporating the use of ancillary equipment such as pumps, filters, blowers, lighting, etc. Finally, the successful application of the tribological principles to influence energy consumption is discussed.

  1. Photovoltaic Manufacturing Technology

    NASA Astrophysics Data System (ADS)

    Easoz, J. R.; Herlocher, R. H.

    1991-12-01

    This report examines the cost-effective manufacture of dendritic-web-based photovoltaic modules. It explains how process changes can increase production and reduce manufacturing costs. Long-range benefits of these improved processes are also discussed. Problems are identified that could impede increasing production and reducing costs; approaches to solve these problems are presented. These approaches involve web growth throughput, cell efficiency, process yield, silicon use, process control, automation, and module efficiency. Also discussed are the benefits of bifacial module design, unique to the dendritic web process.

  2. Manufacturing and producibility technology

    NASA Technical Reports Server (NTRS)

    Hankins, J. D.; Dreshfield, R. L.

    1985-01-01

    Activities of the manufacturing/producibility working group within the Advanced High-Pressure O2/H2 Technology Program are summarized. The objectives of the M/P working group are: to develop and evaluate process and manufacturing techniques for advanced propulsion hardware design and selected materials; and to optimize the producibility of (SSME) components and assemblies by improved performance, increased life, greater reliability, and/or reduced cost. The technologies being developed include: plasma arc, laser, and inertia welding; combustion chamber and turbine blade coatings; coating processes; high performance alloy electroforming; and process control technology.

  3. Photovoltaic manufacturing technology

    SciTech Connect

    Wohlgemuth, J.H.; Whitehouse, D.; Wiedeman, S.; Catalano, A.W.; Oswald, R. )

    1991-12-01

    This report identifies steps leading to manufacturing large volumes of low-cost, large-area photovoltaic (PV) modules. Both crystalline silicon and amorphous silicon technologies were studied. Cost reductions for each step were estimated and compared to Solarex Corporation's manufacturing costs. A cost model, a simple version of the SAMICS methodology developed by the Jet Propulsion Laboratory (JPL), projected PV selling prices. Actual costs of materials, labor, product yield, etc., were used in the cost model. The JPL cost model compared potential ways of lowering costs. Solarex identified the most difficult technical challenges that, if overcome, would reduce costs. Preliminary research plans were developed to solve the technical problems. 13 refs.

  4. Approaches to the manufacture of layered nanocomposites

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Evans, Julian R. G.

    2012-01-01

    Clay-polymer nanocomposites, resulting from industrial research, have emerged as a new class of material because a low addition of clay in a polymer matrix causes dramatic improvement in mechanical and barrier properties. They represent the low volume fraction (<4 vol.%) end of the composition range. The question now is: what will emerge from attempts to explore the high volume fraction (>60 vol.%) end? Naturally occurring materials, such as nacre, show that a combination of a high platelet content in a polymer with a layered structure is strong and tough (4-10 MPa m1/2), even if the reinforcement, aragonite in this case, is inherently brittle (∼1 MPa m1/2). This achievement of nature has inspired the synthesis of materials to mimic the nacre structure using high aspect ratio reinforcements of high elastic modulus such as smectite clay tactoids. Preliminary successes were based on layer-by-layer assembly methods and it will be interesting to find out whether sufficient order can be obtained in composites assembled by more rapid manufacturing pathways. We are interested in the factors affecting dispersion, orientation and intercalation of platelets and here we survey the strategies that have been adopted in order to create organized structures of layered nanocomposites.

  5. A constitutive law for degrading bioresorbable polymers.

    PubMed

    Samami, Hassan; Pan, Jingzhe

    2016-06-01

    This paper presents a constitutive law that predicts the changes in elastic moduli, Poisson's ratio and ultimate tensile strength of bioresorbable polymers due to biodegradation. During biodegradation, long polymer chains are cleaved by hydrolysis reaction. For semi-crystalline polymers, the chain scissions also lead to crystallisation. Treating each scission as a cavity and each new crystal as a solid inclusion, a degrading semi-crystalline polymer can be modelled as a continuum solid containing randomly distributed cavities and crystal inclusions. The effective elastic properties of a degrading polymer are calculated using existing theories for such solid and the tensile strength of the degrading polymer is predicted using scaling relations that were developed for porous materials. The theoretical model for elastic properties and the scaling law for strength form a complete constitutive relation for the degrading polymers. It is shown that the constitutive law can capture the trend of the experimental data in the literature for a range of biodegradable polymers fairly well. PMID:26971070

  6. Expert Systems Application In Manufacturing

    NASA Astrophysics Data System (ADS)

    Som, Pradip; Chitturi, Ramesh; Babu, A. J. G.

    1987-05-01

    Expert system, a special branch of Artificial Intelligence finds its way in the domain of manufacturing. This paper presents the basic ideas and features of the expert systems, problems in manufacturing and application of expert systems in manufacturing. As the process planning is an important phase in manufacturing, the suitability of expert systems for process planning area has been highlighted. Several expert systems, developed to solve manufacturing problems are also discussed in the paper.

  7. Flows in Polymer Networks

    NASA Astrophysics Data System (ADS)

    Tanaka, Fumihiko

    A simple transient network model is introduced to describe creation and annihilation of junctions in the networks of associating polymers. Stationary non-linear viscosity is calculated by the theory and by Monte Carlo simulation to study shear thickening. The dynamic mechanical moduli are calculated as functions of the frequency and the chain disengagement rate. From the peak of the loss modulus, the lifetime τx of the junction is estimated, and from the high frequency plateau of the storage modulus, the number of elastically effective chains in the network is found. Transient phenomena such as stress relaxation and stress overshoot are also theoretically studied. Results are compared with the recent experimental reports on the rheological study of hydrophobically modified water-soluble polymeters.

  8. Computer-aided design of polymers and composites

    NASA Technical Reports Server (NTRS)

    Kaelble, D. H.

    1985-01-01

    This book on computer-aided design of polymers and composites introduces and discusses the subject from the viewpoint of atomic and molecular models. Thus, the origins of stiffness, strength, extensibility, and fracture toughness in composite materials can be analyzed directly in terms of chemical composition and molecular structure. Aspects of polymer composite reliability are considered along with characterization techniques for composite reliability, relations between atomic and molecular properties, computer aided design and manufacture, polymer CAD/CAM models, and composite CAD/CAM models. Attention is given to multiphase structural adhesives, fibrous composite reliability, metal joint reliability, polymer physical states and transitions, chemical quality assurance, processability testing, cure monitoring and management, nondestructive evaluation (NDE), surface NDE, elementary properties, ionic-covalent bonding, molecular analysis, acid-base interactions, the manufacturing science, and peel mechanics.

  9. Shape memory polymers

    DOEpatents

    Wilson, Thomas S.; Bearinger, Jane P.

    2015-06-09

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxyl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  10. MEGARA optical manufacturing process

    NASA Astrophysics Data System (ADS)

    Carrasco, E.; Páez, G.; Granados, F.; Percino, E.; Castillo-Domínguez, E.; Avilés, J. L.; García-Vargas, M. L.; Gil de Paz, A.; Gallego, J.; Iglesias-Páramo, J.; Cedazo, R.

    2014-07-01

    MEGARA is the future visible integral-field and multi-object spectrograph for the GTC 10.4-m telescope located in La Palma. INAOE is a member of the MEGARA Consortium and it is in charge of the Optics Manufacturing work package. MEGARA passed the Optics Detailed Design Review in May 2013, and the blanks of the main optics have been already ordered and their manufacturing is in progress. Except for the optical fibers and microlenses, the complete MEGARA optical system will be manufactured in Mexico, shared between the workshops of INAOE and CIO. This includes a field lens, a 5-lenses collimator, a 7-lenses camera and a complete set of volume phase holographic gratings with 36 flat windows and 24 prisms, being all these elements very large and complex. Additionally, the optical tests and the complete assembly of the camera and collimator subsystems will be carried out in Mexico. Here we describe the current status of the optics manufacturing process.

  11. Advanced Computing for Manufacturing.

    ERIC Educational Resources Information Center

    Erisman, Albert M.; Neves, Kenneth W.

    1987-01-01

    Discusses ways that supercomputers are being used in the manufacturing industry, including the design and production of airplanes and automobiles. Describes problems that need to be solved in the next few years for supercomputers to assume a major role in industry. (TW)

  12. Manufacturing (Industrial) Technician.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This document contains 35 units to consider for use in a tech prep competency profile for the occupation of manufacturing (industrial) technician. All the units listed will not necessarily apply to every situation or tech prep consortium, nor will all the competencies within each unit be appropriate. Several units appear within each specific…

  13. Turbine airfoil manufacturing technology

    SciTech Connect

    Kortovich, C.

    1995-12-31

    The specific goal of this program is to define manufacturing methods that will allow single crystal technology to be applied to complex-cored airfoils components for power generation applications. Tasks addressed include: alloy melt practice to reduce the sulfur content; improvement of casting process; core materials design; and grain orientation control.

  14. Reusing Old Manufacturing Buildings

    ERIC Educational Resources Information Center

    Roman, Harry T.

    2014-01-01

    This article presents an interesting design challenge for students, one that will certainly let them integrate subject matter and get a sense of pride for doing something useful in their own community. The author would be willing to bet that the average town or city has some old red brick manufacturing building(s) that have seen much better days.…

  15. Manufacturing and Merchandising Careers

    ERIC Educational Resources Information Center

    Ryan, Peter J.; And Others

    1977-01-01

    Anyone with a flair for business, product development, or promotion might consider a manufacturing or merchandising occupation. The music industry offers many career opportunities for administrators, salespersons, marketing specialists--the record industry offers positions from promotion manager to rack jobber. Describes instrument company…

  16. Drug development and manufacturing

    DOEpatents

    Warner, Benjamin P.; McCleskey, T. Mark; Burrell, Anthony K.

    2015-10-13

    X-ray fluorescence (XRF) spectrometry has been used for detecting binding events and measuring binding selectivities between chemicals and receptors. XRF may also be used for estimating the therapeutic index of a chemical, for estimating the binding selectivity of a chemical versus chemical analogs, for measuring post-translational modifications of proteins, and for drug manufacturing.

  17. Manufacturing Technology. Curriculum Guide.

    ERIC Educational Resources Information Center

    North Dakota State Board for Vocational Education, Bismarck.

    This guide provides the basic foundation to develop a one-semester course based on the cluster concept, manufacturing technology. One of a set of six guides for an industrial arts curriculum at the junior high school level, it suggests activities that allow students (1) to become familiar with and use some of the tools, materials, and processes…

  18. Illinois Manufacturing Technology Curriculum.

    ERIC Educational Resources Information Center

    Cliffe, Roger; And Others

    This manufacturing technology curriculum involves students in learning problem-solving, communication, team building, quality control, safety, math, science, and technical skills. The document begins with a section on implementation, which gives background information on the purposes and development of the curriculum, explains its rationale,…

  19. Rapid response manufacturing (RRM)

    SciTech Connect

    Cain, W.D.; Waddell, W.L.

    1997-02-18

    US industry is fighting to maintain its competitive edge in the global market place. Today markets fluctuate rapidly. Companies, to survive, have to be able to respond with quick-to-market, improved, high quality, cost efficient products. The way products are developed and brought to market can be improved and made more efficient through the proper incorporation of emerging technologies. The RRM project was established to leverage the expertise and resources of US private industries and federal agencies to develop, integrate, and deploy new technologies that meet critical needs for effective product realization. The RRM program addressed a needed change in the US Manufacturing infrastructure that will ensure US competitiveness in world market typified by mass customization. This project provided the effort needed to define, develop and establish a customizable infrastructure for rapid response product development design and manufacturing. A major project achievement was the development of a broad-based framework for automating and integrating the product and process design and manufacturing activities involved with machined parts. This was accomplished by coordinating and extending the application of feature-based product modeling, knowledge-based systems, integrated data management, and direct manufacturing technologies in a cooperative integrated computing environment. Key technological advancements include a product model that integrates product and process data in a consistent, minimally redundant manner, an advanced computer-aided engineering environment, knowledge-based software aids for design and process planning, and new production technologies to make products directly from design application software.

  20. Nonequilibrium volumetric response of shocked polymers

    SciTech Connect

    Clements, B E

    2009-01-01

    Polymers are well known for their non-equilibrium deviatoric behavior. However, investigations involving both high rate shock experiments and equilibrium measured thermodynamic quantities remind us that the volumetric behavior also exhibits a non-equilibrium response. Experiments supporting the notion of a non-equilibrium volumetric behavior will be summarized. Following that discussion, a continuum-level theory is proposed that will account for both the equilibrium and non-equilibrium response. Upon finding agreement with experiment, the theory is used to study the relaxation of a shocked polymer back towards its shocked equilibrium state.

  1. Manufacturing process of nanofluidics using afm probe

    NASA Astrophysics Data System (ADS)

    Karingula, Varun Kumar

    A new process for fabricating a nano fluidic device that can be used in medical application is developed and demonstrated. Nano channels are fabricated using a nano tip in indentation mode on AFM (Atomic Force Microscopy). The nano channels are integrated between the micro channels and act as a filter to separate biomolecules. Nano channels of 4 to7 m in length, 80nm in width, and at varying depths from 100nm to 850 nm allow the resulting device to separate selected groups of lysosomes and other viruses. Sharply developed vertical micro channels are produced from a deep reaction ion etching followed by deposition of different materials, such as gold and polymers, on the top surface, allowing the study of alternative ways of manufacturing a nanofluidic device. PDMS (Polydimethylsiloxane) bonding is performed to close the top surface of the device. An experimental setup is used to test and validate the device by pouring fluid through the channels. A detailed cost evaluation is conducted to compare the economical merits of the proposed process. It is shown that there is a 47:7% manufacturing time savings and a 60:6% manufacturing cost savings.

  2. Structure-property relationships in graphene/polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Iqbal, Muhammad Z.

    Graphene's unique combination of excellent electrical, thermal, and mechanical properties can provide multi-functional reinforcement for polymer nanocomposites. However, poor dispersion of graphene in non-polar polyolefins limits its applications as a universal filler. Thus, the overall goal of this thesis was to improve graphene's dispersion in graphene/polyolefin nanocomposites and develop processing-structure-property relationships. A new polymer matrix was synthesized by blending polyethylene (PE) with oxidized polyethylene (OPE). Inclusion of OPE in PE produced miscible blends, but the miscibility decreased with increasing OPE loading. Meanwhile, the Young's modulus of blends increased with increasing OPE concentration, attributed to decreased long period order in PE and increased crystallinity. In addition, the miscibility of OPE in PE substantially reduced the viscosity of blends. Using thermally reduced graphene (TRG) produced by simultaneous thermal exfoliation and reduction of graphite oxide, electrically conductive nanocomposites were manufactured by incorporating TRG in PE/OPE blends via solution blending. The rheological and electrical percolations decreased substantially to 0.3 and 0.13 vol% of TRG in PE/OPE/TRG nanocomposites compared to 1.0 and 0.3 vol% in PE/TRG nanocomposites. Improved dispersion of TRG in blends was attributed to increased TRG/polymer interactions, leading to high aspect ratio of the dispersed TRG. A universal Brownian dispersion mechanism for graphene was concluded similar to that of carbon nanotubes, following the Doi-Edwards theory. Furthermore, the improved dispersion of TRG correlated with the formation of surface fractals in PE/OPE/TRG nanocomposites, whereas the poor dispersion of TRG in PE led to the formation of only mass fractals. Moreover, graphene and carbon black (CB) were combined as a synergic filler for manufacturing electrically conductive PE nanocomposites. Smaller fractals were observed at lower CB

  3. Gradient-index ophthalmic lens design and polymer material studies

    NASA Astrophysics Data System (ADS)

    Fischer, David Joel

    Unifocal ophthalmic lenses are conventionally designed using homogeneous glass or plastic materials and aspheric surfaces. The desired power and aberration correction are provided by selection of surface shape and refractive index. This thesis studies the design of ophthalmic lenses utilizing gradient-index (GRIN) materials for both the optical power and aberration control. This is done using geometrical optical theory and ray-tracing simulations. Progressive addition lenses (PALS) are vision correction lenses with a continuous change in power used to treat presbyopia. The power variation is typically located in the lower half of the lens. Progressive addition lenses are currently made with aspheric surfaces to achieve the focal power transition and aberration control. These surfaces have at most, mirror symmetry about the vertical axis. The possible design of progressive addition lenses with GRIN materials has not been well studied. This thesis studies PALS and identifies how gradient-index materials can be used to provide both the power progression and aberration control. The optical theory for rotationally symmetric and asymmetric power additions is given. Analytical and numerical methods for calculating the index profile are used, and the results examined using ray-tracing simulations. The theory developed for ophthalmic lenses is applied to the design of GRIN axicon. This is the first GRIN axicon manufactured, and is fabricated using ion-exchanged GRIN glass. Experimental measurements of its performance are compared and found to match theoretical predictions. This demonstrates the generality of the theory developed: it may be applied to non-visual applications, and even to non-imaging applications. Realistic implementation of GRIN technology to ophthalmic application requires the fabrication of large scale refractive index gradients in polymer material systems. The methyl-methacrylate/styrene copolymer system is studied to develop an empirical model of its

  4. IR laser welding of thin polymer films as a fabrication method for polymer MEMS

    NASA Astrophysics Data System (ADS)

    Beck, William A.; Huang, Michelle; Ketterl, Joe; Hughes, Thayer

    2003-09-01

    MEMS (Micro Electro-Mechanical Systems) continue to be something of a solution looking for a problem. Even as the glamour has moved on to the smaller realm of nano technologies and devices, progress continues towards making micro-scale devices more useful and manufacturable. One avenue this work is taking is into the realm of polymer MEMS, shifting from the expensive, complicated methods of semiconductor processing to the much simpler methods of plastics processing. Polymeric materials are rugged, lightweight and low cost, and their use in manufacturing has a long history. While many bulk polymer manufacturing processes such as molding, machining and adhesive bonding are adaptable to the micro realm, their use in MEMS devices often requires development of specialized processing methods. Here we report on development of laser welding as a bonding method for thin polymer films, including automation of the welding process, steps towards standardization of that process, preparation of standardized test samples, and development of specialized test methods used to evaluate the strength of polymer welds. Our initial results show a direct correlation between welding parameters and weld strengths.

  5. Assembly and performance of silicone polymer waveguides

    NASA Astrophysics Data System (ADS)

    Lostutter, Calob K.; Hodge, Malcolm H.; Marrapode, Thomas R.; Swatowski, Brandon W.; Weidner, W. Ken

    2016-03-01

    We report on the functionality and key performance properties of 50 μm x 50 μm flexible graded index silicone polymer waveguides. The materials show low optical propagation losses of < 0.04 dB/cm @ 850 nm over 1 m lengths as well as stability to 2000 hours 85°C/85% relative humidity and 5 cycles of 260°C solder wave reflow testing. Methods to fabricate large area panels are demonstrated for scaled manufacturing of polymer based optical printed wiring boards. The polymer waveguides are terminated with a passive direct fiber attach method. Fully MPO connectorized waveguide panels are realized and their optical performance properties assessed.

  6. Mechanisms of Hydrocarbon Based Polymer Etch

    NASA Astrophysics Data System (ADS)

    Lane, Barton; Ventzek, Peter; Matsukuma, Masaaki; Suzuki, Ayuta; Koshiishi, Akira

    2015-09-01

    Dry etch of hydrocarbon based polymers is important for semiconductor device manufacturing. The etch mechanisms for oxygen rich plasma etch of hydrocarbon based polymers has been studied but the mechanism for lean chemistries has received little attention. We report on an experimental and analytic study of the mechanism for etching of a hydrocarbon based polymer using an Ar/O2 chemistry in a single frequency 13.56 MHz test bed. The experimental study employs an analysis of transients from sequential oxidation and Ar sputtering steps using OES and surface analytics to constrain conceptual models for the etch mechanism. The conceptual model is consistent with observations from MD studies and surface analysis performed by Vegh et al. and Oehrlein et al. and other similar studies. Parameters of the model are fit using published data and the experimentally observed time scales.

  7. The role of hydrogen bonding in tethered polymer layers

    PubMed Central

    Ren, C.; Nap, R. J.; Szleifer, I.

    2009-01-01

    A molecular theory to study the properties of end tethered polymer layers, in which the polymers have the ability to form hydrogen bonds with water is presented. The approach combines the ideas of the single-chain mean-field theory to treat tethered layers with the approach of Dormidontova (Macromolecules, 2002 35,987) to include hydrogen bonds. The generalization includes the consideration of position dependent polymer-water and water-water hydrogen bonds. The theory is applied to model poly ethylene oxide (PEO) and the predictions are compared with equivalent polymer layers that do not form hydrogen bonds. It is found that increasing the temperature lowers the solubility of the PEO and results in a collapse of the layer at high enough temperatures. The properties of the layer and their temperature dependence are shown to be the result of the coupling between the conformational entropy of the chains, the ability of the polymer to form hydrogen bonds, and the intermolecular interactions. The structural and thermodynamic properties of the PEO layers, such as the lateral pressure-area isotherms and polymer chemical potentials, are studied as a function of temperature and type of tethering surface. The possibility of phase separation of the PEO layer at high enough temperature is predicted, due to the reduced solubility induced by breaking of polymer-water hydrogen bonds. A discussion of the advantages and limitations of the theory, together with how to apply the approach to different hydrogen bonding polymers is presented. PMID:19367906

  8. Making Ceramic/Polymer Parts By Extrusion Stereolithography

    NASA Technical Reports Server (NTRS)

    Stuffle, Kevin; Mulligan, A.; Creegan, P.; Boulton, J. M.; Lombardi, J. L.; Calvert, P. D.

    1996-01-01

    Extrusion stereolithography developmental method of computer-controlled manufacturing of objects out of ceramic/polymer composite materials. Computer-aided design/computer-aided manufacturing (CAD/CAM) software used to create image of desired part and translate image into motion commands for combination of mechanisms moving resin dispenser. Extrusion performed in coordination with motion of dispenser so buildup of extruded material takes on size and shape of desired part. Part thermally cured after deposition.

  9. Fabrication of ceramic components using mold shape deposition manufacturing

    NASA Astrophysics Data System (ADS)

    Cooper, Alexander G.

    Mold Shape Deposition Manufacturing (Mold SDM) is a new process for the fabrication of geometrically complex, structural ceramic components. This thesis describes the development of the Mold SDM process, including process steps, materials selection, planning strategies and automation. Initial characterization results are presented and these are used to compare the process to competing manufacturing processes. A range of current and potential applications for ceramic, as well as metal and polymer parts are discussed. The benefits and limitations of ceramic materials for structural applications are discussed to motivate the need for a manufacturing process capable of rapidly producing high quality, geometrically complex, structural ceramic components. The Mold SDM process was developed to address this need. Mold SDM is based on Shape Deposition Manufacturing (SDM) and uses SDM techniques to build fugitive wax molds which can then be used to build ceramic parts by gelcasting. SDM is an additive-subtractive layered manufacturing process which allows it to build geometrically complex parts. The subtraction step differentiates Mold SDM from other layered manufacturing processes and allows accurate, high quality surfaces to be produced. The performance of the process was increased by identifying the key material properties and then selecting improved materials combinations. Candidate materials were evaluated in terms of machinability, shrinkage, heat resistance and chemical compatibility. A number of preferred materials combinations were developed and used to produce ceramic, metal and polymer parts. A number of new process planning strategies and build techniques were developed. The manufacturability analysis determines whether a part is manufacturable and the orientation selection guidelines help in the selection of optimum build directions. New decomposition techniques take advantage of process capabilities to improve part quality and build rate. Initial process

  10. Multilayer electronic component systems and methods of manufacture

    NASA Technical Reports Server (NTRS)

    Thompson, Dane (Inventor); Wang, Guoan (Inventor); Kingsley, Nickolas D. (Inventor); Papapolymerou, Ioannis (Inventor); Tentzeris, Emmanouil M. (Inventor); Bairavasubramanian, Ramanan (Inventor); DeJean, Gerald (Inventor); Li, RongLin (Inventor)

    2010-01-01

    Multilayer electronic component systems and methods of manufacture are provided. In this regard, an exemplary system comprises a first layer of liquid crystal polymer (LCP), first electronic components supported by the first layer, and a second layer of LCP. The first layer is attached to the second layer by thermal bonds. Additionally, at least a portion of the first electronic components are located between the first layer and the second layer.

  11. Interactions between charged surfaces mediated by stiff, multivalent zwitterionic polymers.

    PubMed

    Bohinc, Klemen; Reščič, Jurij; Lue, Leo

    2016-05-11

    The interaction between like-charged objects in electrolyte solutions can be heavily altered by the presence of multivalent ions which possess a spatially distributed charge. In this work, we examine the influence of stiff, multivalent zwitterionic polymers on the interaction between charged surfaces using a splitting field theory previously shown to be accurate for the weak to the intermediate to the strong electrostatic coupling regimes. The theory is compared to Monte Carlo simulations and good agreement is found between both approaches. For surface separations shorter than the polymer length, the polymers are mainly oriented parallel to the surfaces, and the surface-surface interaction is repulsive. When the surface separation is comparable to the length of polymers, the polymers have two main orientations. The first corresponds to the polymers adsorbed onto the surface with their centers located near to or in contact with the surface; the second corresponds to polymers which are perpendicular to the charged surfaces, bridging both surfaces and leading to an attractive force between them. Increasing the surface charge density leads to more pronounced attraction via bridging. At surface separations greater than the polymer length, the polymers in the center of the system are still mainly perpendicular to the surfaces, due to "chaining" between zwitterions that enable them to bridge the surfaces at larger separations. This leads to an attractive interaction between the surfaces with a range significantly longer than the length of the polymers. PMID:27087406

  12. Loop polymer brushes from polymer single crystals

    NASA Astrophysics Data System (ADS)

    Zhou, Tian; Li, Christopher

    2014-03-01

    Loop polymer brushes represent a category of polymer brushes with both chain ends being tethered to a surface or interface with sufficiently high density. Due to this morphological difference, loop brushes exhibit distinct properties compared with traditional polymer brushes with single chain end being tethered. In our study, α, ω-functionalized polycaprolactone (PCL) single crystals were prepared as templates for polymer brush synthesis. By carefully controlling crystallization condition and immobilization, looped polymer brushes were successfully prepared. Comprehensive studies on the morphology and physical properties of these polymer brushes were carried out using Atomic Force Microscopy and FTIR. Advantages of using this method include exclusive loop morphology, high grafting density, controlled tethering sites and tunable loop size.

  13. Modelling Polymer Deformation during 3D Printing

    NASA Astrophysics Data System (ADS)

    McIlroy, Claire; Olmsted, Peter

    Three-dimensional printing has the potential to transform manufacturing processes, yet improving the strength of printed parts, to equal that of traditionally-manufactured parts, remains an underlying issue. The fused deposition modelling technique involves melting a thermoplastic, followed by layer-by-layer extrusion to fabricate an object. The key to ensuring strength at the weld between layers is successful inter-diffusion. However, prior to welding, both the extrusion process and the cooling temperature profile can significantly deform the polymer micro-structure and, consequently, how well the polymers are able to ``re-entangle'' across the weld. In particular, polymer alignment in the flow can cause de-bonding of the layers and create defects. We have developed a simple model of the non-isothermal extrusion process to explore the effects that typical printing conditions and material rheology have on the conformation of a polymer melt. In particular, we incorporate both stretch and orientation using the Rolie-Poly constitutive equation to examine the melt structure as it flows through the nozzle, the subsequent alignment with the build plate and the resulting deformation due to the fixed nozzle height, which is typically less than the nozzle radius.

  14. Computers in manufacturing

    NASA Astrophysics Data System (ADS)

    Hudson, C. A.

    1982-02-01

    CAD/CAM advances and applications for enhancing productivity in industry are explored. Wide-spread use of CAD/CAM devices are projected to occur by the time period 1992-1997, resulting in a higher percentage of technicians in the manufacturing process, while the cost of computers and software will continue to fall and become more widely available. Computer aided design is becoming a commercially viable system for design and geometric modeling, engineering analysis, kinematics, and drafting, and efforts to bridge the gap between CAD and CAM are indicated, with particular attention given to layering, wherein individual monitoring of different parts of the manufacturing process can be effected without crossover of unnecessary information. The potentials and barriers to the use of robotics are described, with the added optimism that displaced workers to date have moved up to jobs of higher skill and interest.

  15. Perspectives on Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Bourell, David L.

    2016-07-01

    Additive manufacturing (AM) has skyrocketed in visibility commercially and in the public sector. This article describes the development of this field from early layered manufacturing approaches of photosculpture, topography, and material deposition. Certain precursors to modern AM processes are also briefly described. The growth of the field over the last 30 years is presented. Included is the standard delineation of AM technologies into seven broad categories. The economics of AM part generation is considered, and the impacts of the economics on application sectors are described. On the basis of current trends, the future outlook will include a convergence of AM fabricators, mass-produced AM fabricators, enabling of topology optimization designs, and specialization in the AM legal arena. Long-term developments with huge impact are organ printing and volume-based printing.

  16. Manufacturing Materials and Processes. Grade 11-12. Course #8165 (Semester). Technology Education Course Guide. Industrial Arts/Technology Education.

    ERIC Educational Resources Information Center

    North Carolina State Dept. of Public Instruction, Raleigh. Div. of Vocational Education.

    This guide is intended for use in teaching an introductory course in manufacturing materials and processes. The course centers around four basic materials--metallics, polymers, ceramics, and composites--and seven manufacturing processes--casting, forming, molding, separating, conditioning, assembling, and finishing. Concepts and classifications of…

  17. Technology for Manufacturing Efficiency

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The Ground Processing Scheduling System (GPSS) was developed by Ames Research Center, Kennedy Space Center and divisions of the Lockheed Company to maintain the scheduling for preparing a Space Shuttle Orbiter for a mission. Red Pepper Software Company, now part of PeopleSoft, Inc., commercialized the software as their ResponseAgent product line. The software enables users to monitor manufacturing variables, report issues and develop solutions to existing problems.

  18. Advancements in asphere manufacturing

    NASA Astrophysics Data System (ADS)

    Fess, Edward; DeFisher, Scott

    2013-09-01

    Aspheric optics can pose as a challenge to the manufacturing community due to the surface shape and level of quality required. The aspheric surface may have inflection points that limit the usable tool size during manufacturing, or there may be a stringent tolerance on the slope for mid-spatial frequencies that may be problematic for sub-aperture finishing techniques to achieve. As aspheres become more commonplace in the optics community, requests for more complex aspheres have risen. OptiPro Systems has been developing technologies to create a robust aspheric manufacturing process. Contour deterministic microgrinding is performed on a Pro80 or eSX platform. These platforms utilize software and the latest advancements in machine motion to accurately contour the aspheric shape. Then the optics are finished using UltraForm Finishing (UFF), which is a sub-aperture polishing process. This process has the capability to adjust the diameter and compliance of the polishing lap to allow for finishing over a wide range of shapes and conditions. Finally, the aspheric surfaces are qualified using an OptiTrace contact profilometer, or an UltraSurf non-contact 3D surface scanner. The OptiTrace uses a stylus to scan across the surface of the part, and the UltraSurf utilizes several different optical pens to scan the surface and generate a topographical map of the surface under test. This presentation will focus on the challenges for asphere manufacturing, how OptiPro has implemented its technologies to combat these challenges, and provide surface data for analysis.

  19. Electrohydrodynamic Printing and Manufacturing

    NASA Technical Reports Server (NTRS)

    Aksay, Ilhan A. (Inventor); Saville, Dudley A. (Inventor); Poon, Hak Fei (Inventor); Korkut, Sibel (Inventor); Chen, Chuan-hua (Inventor)

    2014-01-01

    An stable electrohydrodynamic filament is obtained by causing a straight electrohydrodynamic filament formed from a liquid to emerge from a Taylor cone, the filament having a diameter of from 10 nm to 100.mu.m. Such filaments are useful in electrohydrodynamic printing and manufacturing techniques and their application in liquid drop/particle and fiber production, colloidal deployment and assembly, and composite materials processing.

  20. Advanced manufacturing: Technology diffusion

    SciTech Connect

    Tesar, A.

    1995-12-01

    In this paper we examine how manufacturing technology diffuses rom the developers of technology across national borders to those who do not have the capability or resources to develop advanced technology on their own. None of the wide variety of technology diffusion mechanisms discussed in this paper are new, yet the opportunities to apply these mechanisms are growing. A dramatic increase in technology diffusion occurred over the last decade. The two major trends which probably drive this increase are a worldwide inclination towards ``freer`` markets and diminishing isolation. Technology is most rapidly diffusing from the US In fact, the US is supplying technology for the rest of the world. The value of the technology supplied by the US more than doubled from 1985 to 1992 (see the Introduction for details). History shows us that technology diffusion is inevitable. It is the rates at which technologies diffuse to other countries which can vary considerably. Manufacturers in these countries are increasingly able to absorb technology. Their manufacturing efficiency is expected to progress as technology becomes increasingly available and utilized.

  1. Manufactured Homes Tool

    Energy Science and Technology Software Center (ESTSC)

    2005-03-09

    The MH Tool software is designed to evaluate existing and new manufactured homes for structural adequacy in high winds. Users define design elements of a manufactured home and then select the hazard(s) for analysis. MH Tool then calculates and reports structural analysis results for the specified design and hazard Method of Solution: Design engineers input information (geometries, materials, etc.) describing the structure of a manufactured home, from which the software automatically creates a mathematical model.more » Windows, doors, and interior walls can be added to the initial design. HUD Code loads (wind, snow loads, interior live loads, etc.) are automatically applied. A finite element analysis is automatically performed using a third party solver to find forces and stresses throughout the structure. The designer may then employ components of strength (and cost) most appropriate for the loads that must be carried at each location, and then re-run the analysis for verification. If forces and stresses are still within tolerable limits (such as the HUD requirements), construction costs would be reduced without sacrificing quality.« less

  2. Manufactured Homes Tool

    SciTech Connect

    2005-03-09

    The MH Tool software is designed to evaluate existing and new manufactured homes for structural adequacy in high winds. Users define design elements of a manufactured home and then select the hazard(s) for analysis. MH Tool then calculates and reports structural analysis results for the specified design and hazard Method of Solution: Design engineers input information (geometries, materials, etc.) describing the structure of a manufactured home, from which the software automatically creates a mathematical model. Windows, doors, and interior walls can be added to the initial design. HUD Code loads (wind, snow loads, interior live loads, etc.) are automatically applied. A finite element analysis is automatically performed using a third party solver to find forces and stresses throughout the structure. The designer may then employ components of strength (and cost) most appropriate for the loads that must be carried at each location, and then re-run the analysis for verification. If forces and stresses are still within tolerable limits (such as the HUD requirements), construction costs would be reduced without sacrificing quality.

  3. Re-Mendable Polymers

    NASA Astrophysics Data System (ADS)

    Bergman, Sheba D.; Wudl, Fred

    Polymers have become an indispensable material resource, representing billions of dollars worth of material consumption every year. The rising prices and exhaust of natural resources such as petroleum, combined with rising environmental concerns, have prompted the development of recyclable and degradable polymers. Polymers that can be reverted back to their monomers or to shorter repolymerizable oligomers, hence, reversible polymers are particularly enticing in this respect because they essentially prevent any material loss with multiple recycling. While reversible polymers have been known for a long time, there has been recent renewed interest in such polymers, since their reversibility can be exploited for repair at the molecular level.

  4. Lipid-absorbing Polymers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr.; Wallace, C. J.

    1973-01-01

    The removal of bile acids and cholesterol by polymeric absorption is discussed in terms of micelle-polymer interaction. The results obtained with a polymer composed of 75 parts PEO and 25 parts PB plus curing ingredients show an absorption of 305 to 309%, based on original polymer weight. Particle size effects on absorption rate are analyzed. It is concluded that crosslinked polyethylene oxide polymers will absorb water, crosslinked polybutadiene polymers will absorb lipids; neither polymer will absorb appreciable amounts of lipids from micellar solutions of lipids in water.

  5. The surface properties of polymer liquids

    SciTech Connect

    Dee, G.T.; Sauer, B.B.

    1995-12-01

    A corresponding states principle is demonstrated for polymer and oligomer liquids. Scaling the measured surface tension with the thermodynamic properties obtained from pressure, volume, and temperature data, one obtains a universal curve. A strict adherence to the corresponding states principle is observed within each oligomer to polymer homologous series. This allows model`s based on equation of state theories to predict the surface tension to within 1% accuracy for such a homologous series. The existence of a strict corresponding states principle implies that for the polymers studied by us, the dominant contribution to the surface tension comes from the cohesive and entropic properties of the bulk liquids. The implications of the corresponding states principle to the prediction of the surface and interfacial tension in polymer melts is outlined.

  6. 77 FR 66179 - Manufacturing Council

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-02

    ... International Trade Administration Manufacturing Council AGENCY: International Trade Administration, U.S... manufacturing council. SUMMARY: On September 14, 2012, the Department of Commerce's International Trade Administration published a notice in the Federal Register (77 FR 56811) soliciting applications for...

  7. 75 FR 80040 - Manufacturing Council

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-21

    ... International Trade Administration Manufacturing Council AGENCY: International Trade Administration, U.S... Manufacturing Council. SUMMARY: On November 23, 2010, the Department of Commerce's International Trade Administration published a notice in the Federal Register (75 FR 71417) soliciting applications to fill...

  8. 75 FR 30781 - Manufacturing Council

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-02

    ... International Trade Administration Manufacturing Council AGENCY: International Trade Administration, U.S... Manufacturing Council. SUMMARY: On March 16, 2010, the Department of Commerce's International Trade Administration published a notice in the Federal Register (75 FR 12507) soliciting applications for membership...

  9. 77 FR 69794 - Manufacturing Council

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-21

    ... International Trade Administration Manufacturing Council AGENCY: International Trade Administration, U.S... Manufacturing Council. SUMMARY: On September 14, 2012, the Department of Commerce's International Trade Administration (ITA) published a notice in the Federal Register (77 FR 56811) soliciting applications...

  10. Dermatitis in rubber manufacturing industries

    SciTech Connect

    White, I.R.

    1988-01-01

    This review describes the history of rubber technology and the manufacturing techniques used in rubber manufacturing industries. The important aspects of the acquisition of allergic and irritant contact dermatitis within the industry are presented for the reader.

  11. Manufacturing a Superconductor in School.

    ERIC Educational Resources Information Center

    Barrow, John

    1989-01-01

    Described is the manufacture of a superconductor from a commercially available kit using equipment usually available in schools or easily obtainable. The construction is described in detail including equipment, materials, safety procedures, tolerances, and manufacture. (Author/CW)

  12. Long polymers near wedges and cones

    NASA Astrophysics Data System (ADS)

    Hammer, Yosi; Kantor, Yacov

    2015-12-01

    We perform a Monte Carlo study of N -step self-avoiding walks, attached to the corner of an impenetrable wedge in two dimensions (d =2 ), or the tip of an impenetrable cone in d =3 , of sizes ranging up to N =106 steps. We find that the critical exponent γα, which determines the dependence of the number of available conformations on N for a cone or wedge with opening angle α , is in good agreement with the theory for d =2 . We study the end-point distribution of the walks in the allowed space and find similarities to the known behavior of random walks (ideal polymers) in the same geometry. For example, the ratio between the mean square end-to-end distances of a polymer near the cone or wedge and a polymer in free space depends linearly on γα, as is known for ideal polymers. We show that the end-point distribution of polymers attached to a wedge does not separate into a product of angular and radial functions, as it does for ideal polymers in the same geometry. The angular dependence of the end position of polymers near the wedge differs from theoretical predictions.

  13. Long polymers near wedges and cones.

    PubMed

    Hammer, Yosi; Kantor, Yacov

    2015-12-01

    We perform a Monte Carlo study of N-step self-avoiding walks, attached to the corner of an impenetrable wedge in two dimensions (d=2), or the tip of an impenetrable cone in d=3, of sizes ranging up to N=10(6) steps. We find that the critical exponent γ(α), which determines the dependence of the number of available conformations on N for a cone or wedge with opening angle α, is in good agreement with the theory for d=2. We study the end-point distribution of the walks in the allowed space and find similarities to the known behavior of random walks (ideal polymers) in the same geometry. For example, the ratio between the mean square end-to-end distances of a polymer near the cone or wedge and a polymer in free space depends linearly on γ(α), as is known for ideal polymers. We show that the end-point distribution of polymers attached to a wedge does not separate into a product of angular and radial functions, as it does for ideal polymers in the same geometry. The angular dependence of the end position of polymers near the wedge differs from theoretical predictions. PMID:26764719

  14. Molecular description of the collapse of hydrophobic polymer chains in water

    NASA Astrophysics Data System (ADS)

    Livadaru, Lucian; Kovalenko, Andriy

    2004-09-01

    We propose a self-consistent molecular theory of conformational properties of flexible polymers in solution. It is applied to the collapse of a hydrophobic polymer chain in water, and can be readily generalized to any polymer-solvent system (e.g., copolymers with high complexity). We stress the potential of this method for a variety of problems, such as protein folding.

  15. Safe food manufacturing.

    PubMed

    Shapiro, A; Mercier, C

    1994-03-31

    Food safety is a growing preoccupation of the health authorities and the major food companies in any European country. All the aspects of food manufacturing, from the raw materials until the product is consumed have to insure they are innoxious to human health, eliminate any harmful effects related either to food handling or consumption in domestic or common eating places, as well as protect, as much as possible, our environment. Thus, the food manufacturer has to examine step-by-step the security of the agro-cultures, their composition, but also the possible residues of pollutants and contaminants, or chemicals used to protect them against various pests and determine the possible loss or retention of these substances during technological processes. Animal raw materials should not contain veterinary drug residues or an abnormal amount of some components that result from inadequate feeding. Care should be taken to ensure the security of foods manufactured by biotechnology processes. The organisms and the whole processes used in food biotechnologies should eliminate any impurities. Any minor food ingredients, such as food additives, are under a permanent revision from the point of view of their safety. The industry reacts immediately if any justification requires that a particular food additive should not be used. In other words all the raw materials must conform to their specifications. Technological processes must create a food with an adequate microbiological quality, e.g. free of pathogens and their toxic metabolites. Any danger of microbiological contamination or accidental pollution, such as mechanical particles, chemical substances, etc. should be eliminated. The particular role of food packaging is crucial, since this is a barrier to protect the food against further parasites or microbial contamination and preserve the food from alterations due to enzymatic reactions that require particular oxygen and water activity conditions. The packaging should also

  16. Development of polymer film solar collectors: A status report

    NASA Astrophysics Data System (ADS)

    Wilhelm, W. G.; Andrews, J. W.

    1982-08-01

    Solar energy collector panels using polymer film and laminate technology were developed which demonstrate low cost and high thermal performance for residential and commercial applications. This device uses common water in the absorber/heat exchanger which is constructed with polymer film adhesively laminated to aluminum foil as the outer surfaces. Stressed polymer films are also used for the outer window and back surface of the panel forming a high strength structural composite. Rigid polymer foam complements the design by contributing insulation and structural definition. This design resulted in very low weight (3.5 kg/m(2)), potentially very low manufacturing cost (aprox. $11/m(2)), and high thermal performance. The development of polymer materials for this technology will be a key to early commercial success.

  17. Energy 101: Clean Energy Manufacturing

    SciTech Connect

    2015-07-09

    Most of us have a basic understanding of manufacturing. It's how we convert raw materials, components, and parts into finished goods that meet our essential needs and make our lives easier. But what about clean energy manufacturing? Clean energy and advanced manufacturing have the potential to rejuvenate the U.S. manufacturing industry and open pathways to increased American competitiveness. Watch this video to learn more about this exciting movement and to see some of these innovations in action.

  18. E-beam-Cure Fabrication of Polymer Fiber/Matrix Composites for Multifunctional Radiation Shielding

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Jensen, Brian J.; Thibeault, Sheila A.; Hou, Tan-Hung; Saether, Erik; Glaessgen, Edward H.; Humes, Donald H.; Chang, Chie K.; Badavi, Francis F.; Kiefer, Rrichard L.; Adams, Dan O.

    2004-01-01

    Aliphatic polymers were identified as optimum radiation polymeric shielding materials for building multifunctional structural elements. Conceptual damage-tolerant configurations of polyolefins have been proposed but many issues on the manufacture remain. In the present paper, we will investigate fabrication technologies with e-beam curing for inclusion of high-strength aliphatic polymer fibers into a highly cross-linked polyolefin matrix. A second stage of development is the fabrication methods for applying face sheets to aliphatic polymer closed-cell foams.

  19. 76 FR 33244 - Manufacturing Council

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-08

    ... International Trade Administration Manufacturing Council AGENCY: International Trade Administration, U.S. Department of Commerce. ACTION: Notice of an Opportunity To Apply for Membership on the Manufacturing Council... Manufacturing Council (Council). The purpose of the Council is to advise the Secretary of Commerce on...

  20. 77 FR 2275 - Manufacturing Council

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-17

    ... International Trade Administration Manufacturing Council AGENCY: International Trade Administration, U.S. Department of Commerce. ACTION: Notice of an opportunity to apply for membership on the Manufacturing Council... Manufacturing Council (Council). The purpose of the Council is to advise the Secretary of Commerce on...

  1. Out of bounds additive manufacturing

    SciTech Connect

    Holshouser, Chris; Newell, Clint; Palas, Sid; Love, Lonnie J.; Kunc, Vlastimil; Lind, Randall F.; Lloyd, Peter D.; Rowe, John C.; Blue, Craig A.; Duty, Chad E.; Peter, William H.; Dehoff, Ryan R.

    2013-03-01

    Lockheed Martin and Oak Ridge National Laboratory are working on an additive manufacturing system capable of manufacturing components measured not in terms of inches or feet, but multiple yards in all dimensions with the potential to manufacture parts that are completely unbounded in size.

  2. Manufacturing Curriculum Grant. Final Report.

    ERIC Educational Resources Information Center

    Scarborough, Jule Dee

    A manufacturing curriculum for secondary vocational programs was designed to bridge the gap between grades 9-10 level courses and the community college-level curriculum of the Illinois Plan for Industrial Education. During the project, a literature review of manufacturing curriculum materials was conducted, a manufacturing conceptual framework was…

  3. Decision Guidance for Sustainable Manufacturing

    ERIC Educational Resources Information Center

    Shao, Guodong

    2013-01-01

    Sustainable manufacturing has significant impacts on a company's business performance and competitiveness in today's world. A growing number of manufacturing industries are initiating efforts to address sustainability issues; however, to achieve a higher level of sustainability, manufacturers need methodologies for formally describing, analyzing,…

  4. Playing with Polymers.

    ERIC Educational Resources Information Center

    Chemecology, 1997

    1997-01-01

    Presents an activity that enables students to gain a better understanding of the importance of polymers. Students perform an experiment in which polymer chains of polyvinyl acetate form crosslinks. Includes background information and discussion questions. (DDR)

  5. Introduction to Polymer Chemistry.

    ERIC Educational Resources Information Center

    Harris, Frank W.

    1981-01-01

    Reviews the physical and chemical properties of polymers and the two major methods of polymer synthesis: addition (chain, chain-growth, or chain-reaction), and condensation (step-growth or step-reaction) polymerization. (JN)

  6. Anion exchange polymer electrolytes

    SciTech Connect

    Kim, Yu Seung; Kim, Dae Sik

    2015-06-02

    Anion exchange polymer electrolytes that include guanidinium functionalized polymers may be used as membranes and binders for electrocatalysts in preparation of anodes for electrochemical cells such as solid alkaline fuel cells.

  7. Polymer composites containing nanotubes

    NASA Technical Reports Server (NTRS)

    Bley, Richard A. (Inventor)

    2008-01-01

    The present invention relates to polymer composite materials containing carbon nanotubes, particularly to those containing singled-walled nanotubes. The invention provides a polymer composite comprising one or more base polymers, one or more functionalized m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers and carbon nanotubes. The invention also relates to functionalized m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers, particularly to m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers having side chain functionalization, and more particularly to m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers having olefin side chains and alkyl epoxy side chains. The invention further relates to methods of making polymer composites comprising carbon nanotubes.

  8. Using Self Consistent Field Theory on Polymeric Mixtures

    NASA Astrophysics Data System (ADS)

    von Konigslow, Kier; Park, Chul; Thompson, Russell

    The ability to predict the solubility of a particular solvent in a polymer fluid is essential to the production of polymer foams. For the past 40 years, the primary model employed to this end has been an expansion of Flory-Huggins lattice fluid theory developed by Sanchez and Lacombe (S-L theory). S-L theory, while useful in the uniform limit, is limited to homogeneous systems. Self-Consistent Field Theory (SCFT), which has long been in use in polymer physics, is a mean-field theory capable of modeling the equilibrium behaviour of both homogeneous and inhomogeneous systems. We are investigating whether SCFT, applied to polymer-solvent mixtures, is in agreement with SL-theory in the homogeneous limit. Should this prove successful, we hope to use SCFT to model more general mixtures, including inhomogeneous nanocellular polymer foam systems.

  9. Effect of manufacturing condition in PC/PMMA/CNT nanocomposites extrusion on the electrical, morphological, and mechanical properties

    NASA Astrophysics Data System (ADS)

    Park, Jutae; Lee, Sangmook; Lee, Jae Wook

    2015-02-01

    Polycarbonate (PC)/poly(methyl methacrylate) (PMMA)/carbon nanotube (CNT) nanocomposites were prepared using a twin screw extruder. The effect of CNT content, screw speed, and manufacturing method on the electrical conductivity, morphology, and mechanical properties were investigated using a surface resistivity meter, SEM, XRD, and UTM. There existed the processing condition which lowered the surface resistivity of nanocomposites considerably. Three different manufacturing methods were tested on the effectiveness of CNTs and the expected mechanism was proposed. The electrical conductive nanocomposites were obtained using the incompatibility between the polymers, the difference of affinity of the polymers to CNTs, an optimum processing condition, and a proper manufacturing method.

  10. Rational design and synthesis of semi-conducting polymers.

    SciTech Connect

    Wong, Bryan Matthew; Reeder, Craig; Cordaro, Joseph Gabriel

    2010-12-01

    A rational approach was used to design polymeric materials for thin-film electronics applications, whereby theoretical modeling was used to determine synthetic targets. Time-dependent density functional theory calculations were used as a tool to predict the electrical properties of conjugated polymer systems. From these results, polymers with desirable energy levels and band-gaps were designed and synthesized. Measurements of optoelectronic properties were performed on the synthesized polymers and the results were compared to those of the theoretical model. From this work, the efficacy of the model was evaluated and new target polymers were identified.

  11. Chemical inertness of UV-cured optical elastomers within the printed circuit board manufacturing process for embedded waveguide applications

    NASA Astrophysics Data System (ADS)

    Kruse, Kevin; Walczak, Karl; Thomas, Nicholas; Swatowski, Brandon; Demars, Casey; Middlebrook, Christopher

    2014-03-01

    Embedding polymer optical waveguides (WGs) into printed circuit boards (PCBs) for intra-board or board-to-board high speed data communications requires polymer materials that are compatible and inert when exposed to common PCB manufacturing processes. Ensuring both WG functionality after chemical exposure and maintaining PCB manufacturing integrities within the production process is crucial for successful implementation. The PCB manufacturing flow is analyzed to expose major requirements that would be required for the successful implementation of polymer materials for embedded WG development. Chemical testing and analysis were performed on Dow Corning ® OE-4140 UV-Cured Optical Elastomer Core and Dow Corning® OE-4141 UV-Cured Optical Elastomer Cladding which are designed for low loss embedded optical WGs. Contamination testing was conducted to demonstrate polymer compatibility in both cured and uncured form. Various PCB chemicals were treated with uncured polymer material and tested for effective contamination. Fully polymerized multimode WGs were fabricated and exposed to PCB chemicals at temperatures and durations comparable to PCB manufacturing conditions. Chemical analysis shows that the chosen polymer is compatible and inert with most common PCB manufacturing processes.

  12. Influence of Crowding on Polymer Conformations in Polymer-Nanoparticle Mixtures: Monte Carlo Simulations

    NASA Astrophysics Data System (ADS)

    Lim, Wei Kang; Denton, Alan R.

    2014-03-01

    Within the cytoplasm and nucleoplasm of eukaryotic cells, a complex mixture of macromolecules (biopolymers, such as proteins and RNA) and smaller molecules share a tightly restricted space. In this crowded environment, hard nanoparticles exclude volume to softer biopolymer coils, restricting protein and RNA conformations and folding pathways. At sufficiently high concentrations, nanoparticle crowding also can affect phase stability, inducing aggregation or separation into polymer-rich and polymer-poor phases. Through Monte Carlo simulations, we explore the impact of crowding on polymer conformations and phase behavior in a coarse-grained model of polymer-nanoparticle mixtures. Neglecting polymer self-interactions, we exploit the random-walk geometry of ideal coils to model the polymers as effective ellipsoids whose shapes fluctuate according to the probability distribution of the gyration tensor. Accounting for penetration of polymers by smaller nanoparticles, we calculate the crowding-induced shift in the polymer shape distribution. We compare our results with predictions of a free-volume theory and available experimental data. This work was supported by the National Science Foundation under Grant No. DMR-1106331.

  13. Polymer-Induced Depletion Interaction and Its Effect on Colloidal Sedimentation in Colloid-Polymer Mixtures

    NASA Technical Reports Server (NTRS)

    Tong, Penger

    1996-01-01

    In this paper we focus on the polymer-induced depletion attraction and its effect on colloidal sedimentation in colloid-polymer mixtures. We first report a small angle neutron scattering (SANS) study of the depletion effect in a mixture of hard-sphere-like colloid and non-adsorbing polymer. Then we present results of our recent sedimentation measurements in the same colloid-polymer mixture. A key parameter in controlling the sedimentation of heavy colloidal particles is the interparticle potential U(tau), which is the work required to bring two colloidal particles from infinity to a distance tau under a give solvent condition. This potential is known to affect the average settling velocity of the particles and experimentally one needs to have a way to continuously vary U(tau) in order to test the theory. The interaction potential U(tau) can be altered by adding polymer molecules into the colloidal suspension. In a mixture of colloid and non-adsorbing polymer, the potential U(tau) can develop an attractive well because of the depletion effect, in that the polymer chains are expelled from the region between two colloidal particles when their surface separation becomes smaller than the size of the polymer chains. The exclusion of polymer molecules from the space between the colloidal particles leads to an unbalanced osmotic pressure difference pushing the colloidal particles together, which results in an effective attraction between the two colloidal particles. The polymer-induced depletion attraction controls the phase stability of many colloid-polymer mixtures, which are directly of interest to industry.

  14. Poly-phenylated diamines and their use as polycondensation monomers in the synthesis of polyamide, poly(amide-imide), and polyimide polymers

    NASA Technical Reports Server (NTRS)

    Harris, Frank W. (Inventor)

    1992-01-01

    New polyphenylated polynuclear aromatic diamines, such as 1,3-bis[4-aminophenyl]-2,3,5-triphenylbenzene, a process for their manufacture and their use as polycondensation components for the manufacture of polyamide, polyamide-imide and polyimide polymers are described. The polymers obtained with the aromatic diamines according to the invention are readily soluble, rigid-rod polymers and are distinguished by outstanding modulus, tensile compression strength, energy absorption, coefficient of expansion and electrical properties.

  15. Metal Additive Manufacturing: A Review

    NASA Astrophysics Data System (ADS)

    Frazier, William E.

    2014-06-01

    This paper reviews the state-of-the-art of an important, rapidly emerging, manufacturing technology that is alternatively called additive manufacturing (AM), direct digital manufacturing, free form fabrication, or 3D printing, etc. A broad contextual overview of metallic AM is provided. AM has the potential to revolutionize the global parts manufacturing and logistics landscape. It enables distributed manufacturing and the productions of parts-on-demand while offering the potential to reduce cost, energy consumption, and carbon footprint. This paper explores the material science, processes, and business consideration associated with achieving these performance gains. It is concluded that a paradigm shift is required in order to fully exploit AM potential.

  16. Multiscale modeling of polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Sheidaei, Azadeh

    In recent years, polymer nano-composites (PNCs) have increasingly gained more attention due to their improved mechanical, barrier, thermal, optical, electrical and biodegradable properties in comparison with the conventional micro-composites or pristine polymer. With a modest addition of nanoparticles (usually less than 5wt. %), PNCs offer a wide range of improvements in moduli, strength, heat resistance, biodegradability, as well as decrease in gas permeability and flammability. Although PNCs offer enormous opportunities to design novel material systems, development of an effective numerical modeling approach to predict their properties based on their complex multi-phase and multiscale structure is still at an early stage. Developing a computational framework to predict the mechanical properties of PNC is the focus of this dissertation. A computational framework has been developed to predict mechanical properties of polymer nano-composites. In chapter 1, a microstructure inspired material model has been developed based on statistical technique and this technique has been used to reconstruct the microstructure of Halloysite nanotube (HNT) polypropylene composite. This technique also has been used to reconstruct exfoliated Graphene nanoplatelet (xGnP) polymer composite. The model was able to successfully predict the material behavior obtained from experiment. Chapter 2 is the summary of the experimental work to support the numerical work. First, different processing techniques to make the polymer nanocomposites have been reviewed. Among them, melt extrusion followed by injection molding was used to manufacture high density polyethylene (HDPE)---xGnP nanocomposties. Scanning electron microscopy (SEM) also was performed to determine particle size and distribution and to examine fracture surfaces. Particle size was measured from these images and has been used for calculating the probability density function for GNPs in chapter 1. A series of nanoindentation tests have

  17. Variational modeling of ionic polymer plate structures

    NASA Astrophysics Data System (ADS)

    Buechler, Miles A.; Leo, Donald J.

    2006-03-01

    Ionomeric polymers are a promising class of intelligent material which exhibit electromechanical coupling similar to that of piezoelectric bimorphs. Ionomeric polymers are much more compliant than piezoelectric ceramics or polymers and have been shown to produce actuation strain on the order of 5% at operating voltages between 1 V and 5 V. This performance indicates the potential for self-actuating devices manufactured from ionomeric polymers, such as deformable mirrors or low pressure pump diaphragms. This paper presents a variational approach to the dynamic modeling of ionic polymer plates in rectangular coordinates. A linear matrix equation, which relates displacement and charge to applied forces and voltage, is developed to determine the response of the structure to applied forces and applied potentials. The modeling method is based on the incorporation of empirically determined material properties, which have been shown to be highly frequency dependent. The matrices are calculated at discrete frequencies and solved frequency-by-frequency to determine the response of the ionomeric plate structures. A model of a thin rectangular plate is developed and validated experimentally. Simulated frequency response functions are compared to experimental results for several locations on the plate. The response of the plate at certain frequencies is computed and compared to experimentally-determined response shapes. The results demonstrate the validity of the modeling approach in predicting the dynamic response of the ionomeric plate structure. These spatial solutions are also compared to experimentally determined response shapes.

  18. Precise Measurement for Manufacturing

    NASA Technical Reports Server (NTRS)

    2003-01-01

    A metrology instrument known as PhaseCam supports a wide range of applications, from testing large optics to controlling factory production processes. This dynamic interferometer system enables precise measurement of three-dimensional surfaces in the manufacturing industry, delivering speed and high-resolution accuracy in even the most challenging environments.Compact and reliable, PhaseCam enables users to make interferometric measurements right on the factory floor. The system can be configured for many different applications, including mirror phasing, vacuum/cryogenic testing, motion/modal analysis, and flow visualization.

  19. Evaporation in space manufacturing

    NASA Technical Reports Server (NTRS)

    Li, C. H.

    1974-01-01

    'Normal evaporation' equations for predicting the compositional changes with time and temperature have been developed and correlated with actual experimental data. An evaporative congruent temperature is defined and used to explain, predict, or plan space experiments on anomalous constitutional melting (on cooling) or solidification (on heating). Uneven evaporation causes reactive jetting forces capable of initiating new convection currents, nongravitational accelerations, surface vibrations, or other disturbances. Applications of evaporation to space manufacturing are described concerning evaporative purification, surface cooling, specimen selection, particles splitting, freezing data interpretation, material loss and dimensional control, and surface contamination or compositional changes.

  20. Manufactured soil screening test

    SciTech Connect

    1999-05-01

    The purpose of this technical note is to provide a screening test that can be used to evaluate the potential for manufacturing artificial soil using dredged material, cellulose waste materials (e.g., yard waste compost, sawdust, wastepaper), and biosolids (e.g., N-Viro-reconditioned sewage sludge, BIONSOIL-reconstituted cow manure). This procedure will allow the most productive blend of any dredged material (uncontaminated or contaminated), cellulose, and biosolids to be determined and recommended for use in an environmentally productive and beneficial manner.

  1. Evolution of solidification texture during additive manufacturing

    PubMed Central

    Wei, H. L.; Mazumder, J.; DebRoy, T.

    2015-01-01

    Striking differences in the solidification textures of a nickel based alloy owing to changes in laser scanning pattern during additive manufacturing are examined based on theory and experimental data. Understanding and controlling texture are important because it affects mechanical and chemical properties. Solidification texture depends on the local heat flow directions and competitive grain growth in one of the six <100> preferred growth directions in face centered cubic alloys. Therefore, the heat flow directions are examined for various laser beam scanning patterns based on numerical modeling of heat transfer and fluid flow in three dimensions. Here we show that numerical modeling can not only provide a deeper understanding of the solidification growth patterns during the additive manufacturing, it also serves as a basis for customizing solidification textures which are important for properties and performance of components. PMID:26553246

  2. Printability of alloys for additive manufacturing

    DOE PAGESBeta

    Mukherjee, T.; Zuback, J. S.; De, A.; DebRoy, T.

    2016-01-22

    Although additive manufacturing (AM), or three dimensional (3D) printing, provides significant advantages over existing manufacturing techniques, metallic parts produced by AM are susceptible to distortion, lack of fusion defects and compositional changes. Here we show that the printability, or the ability of an alloy to avoid these defects, can be examined by developing and testing appropriate theories. A theoretical scaling analysis is used to test vulnerability of various alloys to thermal distortion. A theoretical kinetic model is used to examine predisposition of different alloys to AM induced compositional changes. A well-tested numerical heat transfer and fluid flow model is usedmore » to compare susceptibilities of various alloys to lack of fusion defects. These results are tested and validated with independent experimental data. Here, the findings presented in this paper are aimed at achieving distortion free, compositionally sound and well bonded metallic parts.« less

  3. Printability of alloys for additive manufacturing.

    PubMed

    Mukherjee, T; Zuback, J S; De, A; DebRoy, T

    2016-01-01

    Although additive manufacturing (AM), or three dimensional (3D) printing, provides significant advantages over existing manufacturing techniques, metallic parts produced by AM are susceptible to distortion, lack of fusion defects and compositional changes. Here we show that the printability, or the ability of an alloy to avoid these defects, can be examined by developing and testing appropriate theories. A theoretical scaling analysis is used to test vulnerability of various alloys to thermal distortion. A theoretical kinetic model is used to examine predisposition of different alloys to AM induced compositional changes. A well-tested numerical heat transfer and fluid flow model is used to compare susceptibilities of various alloys to lack of fusion defects. These results are tested and validated with independent experimental data. The findings presented in this paper are aimed at achieving distortion free, compositionally sound and well bonded metallic parts. PMID:26796864

  4. Evolution of solidification texture during additive manufacturing

    DOE PAGESBeta

    Wei, H. L.; Mazumder, J.; DebRoy, T.

    2015-11-10

    Striking differences in the solidification textures of a nickel based alloy owing to changes in laser scanning pattern during additive manufacturing are examined based on theory and experimental data. Understanding and controlling texture are important because it affects mechanical and chemical properties. Solidification texture depends on the local heat flow directions and competitive grain growth in one of the six <100> preferred growth directions in face centered cubic alloys. Furthermore, the heat flow directions are examined for various laser beam scanning patterns based on numerical modeling of heat transfer and fluid flow in three dimensions. Here we show that numericalmore » modeling can not only provide a deeper understanding of the solidification growth patterns during the additive manufacturing, it also serves as a basis for customizing solidification textures which are important for properties and performance of components.« less

  5. Evolution of solidification texture during additive manufacturing

    SciTech Connect

    Wei, H. L.; Mazumder, J.; DebRoy, T.

    2015-11-10

    Striking differences in the solidification textures of a nickel based alloy owing to changes in laser scanning pattern during additive manufacturing are examined based on theory and experimental data. Understanding and controlling texture are important because it affects mechanical and chemical properties. Solidification texture depends on the local heat flow directions and competitive grain growth in one of the six <100> preferred growth directions in face centered cubic alloys. Furthermore, the heat flow directions are examined for various laser beam scanning patterns based on numerical modeling of heat transfer and fluid flow in three dimensions. Here we show that numerical modeling can not only provide a deeper understanding of the solidification growth patterns during the additive manufacturing, it also serves as a basis for customizing solidification textures which are important for properties and performance of components.

  6. Printability of alloys for additive manufacturing

    PubMed Central

    Mukherjee, T.; Zuback, J. S.; De, A.; DebRoy, T.

    2016-01-01

    Although additive manufacturing (AM), or three dimensional (3D) printing, provides significant advantages over existing manufacturing techniques, metallic parts produced by AM are susceptible to distortion, lack of fusion defects and compositional changes. Here we show that the printability, or the ability of an alloy to avoid these defects, can be examined by developing and testing appropriate theories. A theoretical scaling analysis is used to test vulnerability of various alloys to thermal distortion. A theoretical kinetic model is used to examine predisposition of different alloys to AM induced compositional changes. A well-tested numerical heat transfer and fluid flow model is used to compare susceptibilities of various alloys to lack of fusion defects. These results are tested and validated with independent experimental data. The findings presented in this paper are aimed at achieving distortion free, compositionally sound and well bonded metallic parts. PMID:26796864

  7. Printability of alloys for additive manufacturing

    NASA Astrophysics Data System (ADS)

    Mukherjee, T.; Zuback, J. S.; de, A.; Debroy, T.

    2016-01-01

    Although additive manufacturing (AM), or three dimensional (3D) printing, provides significant advantages over existing manufacturing techniques, metallic parts produced by AM are susceptible to distortion, lack of fusion defects and compositional changes. Here we show that the printability, or the ability of an alloy to avoid these defects, can be examined by developing and testing appropriate theories. A theoretical scaling analysis is used to test vulnerability of various alloys to thermal distortion. A theoretical kinetic model is used to examine predisposition of different alloys to AM induced compositional changes. A well-tested numerical heat transfer and fluid flow model is used to compare susceptibilities of various alloys to lack of fusion defects. These results are tested and validated with independent experimental data. The findings presented in this paper are aimed at achieving distortion free, compositionally sound and well bonded metallic parts.

  8. Metal-polymer and polymer-polymer interfaces: Application to conjugated polymer electronic devices

    NASA Astrophysics Data System (ADS)

    Smallfield, Julie Anne Osladil

    The study of metal-polymer and polymer-polymer interfaces is applied to conjugated polymer electronic devices. Conjugated polymers are a class of organic materials which have metallic or semiconducting properties which are being investigated as alternatives to traditional semiconducting materials. When conjugated polymers are used in devices, the interfaces are found to be critical to device performance. X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS), which give information about the atomic and chemical composition, workfunction, and ionization potential of materials, are used to study these interfaces. In studying metal-polymer interfaces, it is shown that the interface between the conjugated polymer fully sulfonated polyaniline (NSPAN) and an aluminum alloy is an active interface, in which copper is extracted by the polymer from the aluminum alloy. This results in the aluminum alloy becoming more resistant to corrosion in a salty environment. The interface between aluminum and NSPAN, as it is found in some light emitting devices (LEDS), is also studied. It is concluded that negative charge is transferred from the aluminum to the polymer, resulting in a thin layer of oxidized aluminum and a more reduced form of the polymer at the interface. In studying polymer-polymer interfaces, it is proposed that NSPAN protonates a pyridine containing polymer at an interface which is also found in some LEDs. This is proposed to be responsible for color variation found in some LEDs. A model system was studied, and protonation at the polymer-polymer interface was directly observed, supporting the earlier proposals. Polymer-polymer interfaces found in SCALE devices, which are LEDs made with three polymer layers, are studied by UPS to determine the band structure of these devices. It is concluded that the EB layers decrease the hole barrier and increase the electron barrier, which leads to better charge balance and a better device. The EB

  9. FOREWORD: Focus on the Degradation and Stability of Polymers

    NASA Astrophysics Data System (ADS)

    Terano, Minoru

    2008-06-01

    Modern society is so reliant on polymers that products incorporating these macromolecules are almost 'invisible'. Polymers are indispensable materials used for manufacturing compact disks, clothes, lightweight airplanes, automobiles, footware and even the humble polystyrene boxes for packing our favorite hamburgers and fries. But, like many other materials, polymers degrade and become unstable, so a deeper understanding of the physical mechanisms responsible for degradation is necessary to address issues such as potential applications, recycling and the impact of polymer-products on the environment. In particular, polymers are highly vulnerable to oxidative degradation at elevated temperatures and in sunlight. Unfortunately, in spite of extensive research on polymer degradation, our knowledge is still incomplete. The analysis of polymer degradation and stability has recently become harder and more complicated because of the wider range of polymer applications, including blends and composites. Notably, composites with nanofillers are being studied for automotive, electrical and other industrial applications. With this background, the 1st International Symposium on Ultimate Stability of NanoStructured Polymers and Composites (NT2007) was held in October at the Japan Advanced Institute of Science and Technology in Ishikawa Prefecture. The meeting provided a forum to discuss advanced research achievements to resolve problems in this field of research. The papers selected for this focus issue describe recent discoveries on the stability, weatherability and flame retardancy of polymers, as well as providing an insight into degradation mechanisms of nanostructured polymers and composites. We hope that this focus issue will serve as a timely source of information about one of the most important topics in polymer science and related technologies.

  10. Integral equation study of particle confinement effects in a polymer/particle mixture

    SciTech Connect

    Henderson, D; Trokhymchuk, A; Kalyuzhnyi, Y; Gee, R; Lacevic, N

    2007-05-09

    Integral equation theory techniques are applied to evaluate the structuring of the polymer when large solid particles are embedded into a bulk polymer melt. The formalism presented here is applied to obtain an insight into the filler particle aggregation tendency. We find that with the employed polymer-particle interaction model it is very unlikely that the particles will aggregate. We believe that in such a system aggregation and clustering can occur when the filler particles are dressed by tightly bound polymer layers.

  11. LIQUID CRYSTAL POLYMERS (LCP) USED AS A MACHINING FLUID CD

    EPA Science Inventory

    This interactive CD was produced to present the science, research activities, and beneficial environmental and machining advantages for utilizing Liquid Crystal Polymers (LCPs) as a machine fluid in the manufacturing industry.

    In 1995, the USEPA funded a project to cut flu...

  12. Water sorption and diffusion in glassy polymers

    NASA Astrophysics Data System (ADS)

    Davis, Eric Mikel

    Water sorption and diffusion in glassy polymers is important in many fields, including drug delivery, desalination, energy storage and delivery, and packaging. Accurately measuring and understanding the underlying transport mechanisms of water in these glassy polymers is often complex due to both the nonequilibrium state of the polymer and the self-associating nature of water (e.g., hydrogen bonding). In this work, water sorption and diffusion in a number of glassy polymers were measured using gravimetric and spectroscopic techniques, including quartz spring microbalance, quartz crystal microbalance, and in situ time-resolved Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy. Non-Fickian diffusion was observed in all polymers studied, indicated by an initial stage of water uptake, followed by a second stage of continuous, gradual uptake of water at later experimental times. These phenomena were attributed to diffusion driven by a concentration gradient, as well as diffusion driven by slow polymer relaxation resulting in additional water ingress over time. In order to gain additional insight into these phenomena, which are a product of nonequilibrium state of the polymers, diffusion-relaxation models were developed and employed to determine the time scales for both diffusion and polymer relaxation, where the ratio of these values (Deborah number) confirmed the observed non-Fickian water diffusion. In addition, the solubility of water in these polymers was predicted using two nonequilibrium thermodynamic models: the nonequilibrium lattice fluid (NELF) model and the nonequilibrium statistical associating fluid theory (NE-SAFT), where excellent agreement between the NE-SAFT predictions and experimental data was obtained over the entire water vapor activity range explored. Furthermore, the states of water were analyzed using the Zimm-Lundberg clustering theory, as well as in situ FTIR-ATR spectroscopy, where the latter technique provides a

  13. Structure Property Studies for Additively Manufactured Parts

    SciTech Connect

    Milenski, Helen M; Schmalzer, Andrew Michael; Kelly, Daniel

    2015-08-17

    Since the invention of modern Additive Manufacturing (AM) processes engineers and designers have worked hard to capitalize on the unique building capabilities that AM allows. By being able to customize the interior fill of parts it is now possible to design components with a controlled density and customized internal structure. The creation of new polymers and polymer composites allow for even greater control over the mechanical properties of AM parts. One of the key reasons to explore AM, is to bring about a new paradigm in part design, where materials can be strategically optimized in a way that conventional subtractive methods cannot achieve. The two processes investigated in my research were the Fused Deposition Modeling (FDM) process and the Direct Ink Write (DIW) process. The objectives of the research were to determine the impact of in-fill density and morphology on the mechanical properties of FDM parts, and to determine if DIW printed samples could be produced where the filament diameter was varied while the overall density remained constant.

  14. Magnet cable manufacturing

    SciTech Connect

    Royet, J.

    1990-10-01

    The cable is the heart of a superconducting accelerator magnet. Since the initial development of the Rutherford Cable more than twenty years ago, many improvements in manufacturing techniques have increased the current carrying capacity. When the Tevatron cable was specified fifteen years ago the current carrying capacity was 1800 A/mm{sup 2} at a field of 5.3T. During the intervening years it has been increased to 3000 A/mm{sup 2}. These improvements were due to refinements in the fabrication of the strands and the formation of the cable from the strands. The metallurgists were able to impart significant gains in performance by improving the homogeneity of the conductor. The engineers and technicians who designed and built the modern cabling machines made an enormous contribution by significantly reducing the degradation of wire performance that occurs when the wire was cabled. The fact that these gains were made while increasing the speed of cabling is one of the technological advances that made accelerators like the SSC possible. This article describes the cabling machines that were built to manufacture the cable for the full scale SSC prototype magnets and the low beta quadrupoles for the Fermilab Tevatron. This article also presents a compendium of the knowledge that was gained in the struggle to make high performance cable to exacting dimensional standards and at the throughput needed for the SSC. The material is an important part of the technology transfer from the Department of energy Laboratories to Industry.

  15. Polyolefin catalyst manufacturing

    SciTech Connect

    Inkrott, K.E.; Scinta, J.; Smith, P.D. )

    1989-10-16

    Statistical process control (SPC) procedures are absolutely essential for making new-generation polyolefin catalysts with the consistent high quality required by modern polyolefin processes. Stringent quality assurance is critical to the production of today's high-performance catalysts. Research and development efforts during the last 20 years have led to major technological improvements in the polyolefin industry. New generation catalysts, which once were laboratory curiosities, must now be produced commercially on a regular and consistent basis to meet the increasing requirements of the plastics manufacturing industry. To illustrate the more stringent requirements for producing the new generation polyolefin catalysts, the authors compare the relatively simple, first-generation polypropylene catalyst production requirements with some of the basic requirements of manufacturing a more complex new-generation catalyst, such as Catalyst Resources Inc.'s LYNX 900. The principles which hold true for the new-generation catalysts such as LYNX 900 are shown to apply equally to the scale-up of other advanced technology polyolefin catalysts.

  16. OPINION: Safe exponential manufacturing

    NASA Astrophysics Data System (ADS)

    Phoenix, Chris; Drexler, Eric

    2004-08-01

    In 1959, Richard Feynman pointed out that nanometre-scale machines could be built and operated, and that the precision inherent in molecular construction would make it easy to build multiple identical copies. This raised the possibility of exponential manufacturing, in which production systems could rapidly and cheaply increase their productive capacity, which in turn suggested the possibility of destructive runaway self-replication. Early proposals for artificial nanomachinery focused on small self-replicating machines, discussing their potential productivity and their potential destructiveness if abused. In the light of controversy regarding scenarios based on runaway replication (so-called 'grey goo'), a review of current thinking regarding nanotechnology-based manufacturing is in order. Nanotechnology-based fabrication can be thoroughly non-biological and inherently safe: such systems need have no ability to move about, use natural resources, or undergo incremental mutation. Moreover, self-replication is unnecessary: the development and use of highly productive systems of nanomachinery (nanofactories) need not involve the construction of autonomous self-replicating nanomachines. Accordingly, the construction of anything resembling a dangerous self-replicating nanomachine can and should be prohibited. Although advanced nanotechnologies could (with great difficulty and little incentive) be used to build such devices, other concerns present greater problems. Since weapon systems will be both easier to build and more likely to draw investment, the potential for dangerous systems is best considered in the context of military competition and arms control.

  17. Extensional Flow of Bulk Polymers

    NASA Technical Reports Server (NTRS)

    Peng, T. J.

    1972-01-01

    A study was made of the behavior of polyisobutylene under motion at a constant stretch history for both strip biaxial extensional flow and simple extensional flow. Steady-state non-Newtonian viscosities were observed at various constant stretch histories. Newtonian viscosities for both strip biaxial and simple extensional flow were found to be in agreement with the classical theory. The results of the study provide an essential part of the experimental background necessary for the development of a new general stress-strain-time relation for uncrosslinked and lightly crosslinked polymers.

  18. Nanoporous polymer electrolyte

    SciTech Connect

    Elliott, Brian; Nguyen, Vinh

    2012-04-24

    A nanoporous polymer electrolyte and methods for making the polymer electrolyte are disclosed. The polymer electrolyte comprises a crosslinked self-assembly of a polymerizable salt surfactant, wherein the crosslinked self-assembly includes nanopores and wherein the crosslinked self-assembly has a conductivity of at least 1.0.times.10.sup.-6 S/cm at 25.degree. C. The method of making a polymer electrolyte comprises providing a polymerizable salt surfactant. The method further comprises crosslinking the polymerizable salt surfactant to form a nanoporous polymer electrolyte.

  19. Depletion-induced forces and crowding in polymer-nanoparticle mixtures: Role of polymer shape fluctuations and penetrability.

    PubMed

    Lim, Wei Kang; Denton, Alan R

    2016-01-14

    Depletion forces and macromolecular crowding govern the structure and function of biopolymers in biological cells and the properties of polymer nanocomposite materials. To isolate and analyze the influence of polymer shape fluctuations and penetrability on depletion-induced interactions and crowding by nanoparticles, we model polymers as effective penetrable ellipsoids, whose shapes fluctuate according to the probability distributions of the eigenvalues of the gyration tensor of an ideal random walk. Within this model, we apply Monte Carlo simulation methods to compute the depletion-induced potential of mean force between hard nanospheres and crowding-induced shape distributions of polymers in the protein limit, in which polymer coils can be easily penetrated by smaller nanospheres. By comparing depletion potentials from simulations of ellipsoidal and spherical polymer models with predictions of polymer field theory and free-volume theory, we show that polymer depletion-induced interactions and crowding depend sensitively on polymer shapes and penetrability, with important implications for bulk thermodynamic phase behavior. PMID:26772587

  20. Examination of the fundamental relation between ionic transport and segmental relaxation in polymer electrolytes

    SciTech Connect

    Wang, Yangyang; Fan, Fei; Agapov, Alexander L; Saito, Tomonori; Yang, Jun; Yu, Xiang; Hong, Kunlun; Mays, Jimmy; Sokolov, Alexei P

    2014-01-01

    Replacing traditional liquid electrolytes by polymers will significantly improve electrical energy storage technologies. Despite significant advantages for applications in electrochemical devices, the use of solid polymer electrolytes is strongly limited by their poor ionic conductivity. The classical theory predicts that the ionic transport is dictated by the segmental motion of the polymer matrix. As a result, the low mobility of polymer segments is often regarded as the limiting factor for development of polymers with sufficiently high ionic conductivity. Here, we show that the ionic conductivity in many polymers can be strongly decoupled from their segmental dynamics, in terms of both temperature dependence and relative transport rate. Based on this principle, we developed several polymers with superionic conductivity. The observed fast ion transport suggests a fundamental difference between the ionic transport mechanisms in polymers and small molecules and provides a new paradigm for design of highly conductive polymer electrolytes.