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作者： Badami, Anand S. Lee, Hae-Seung Li, Yanxiang Roy, Abhishek Wang, Hang McGrath, James E. Department of Chemistry Macromolecular Science and Engineering Program Macromolecules and Interfaces Institute State University Blacksburg VA 24061 United States Dow Chemical Company 1897 Building Midland MI 48667 United States Dow Chemical Company 1707 Building Midland MI 48674 United States Dow Chemical Company 5400 Dewey Hill Rd. Edina MN 55439 United States Celanese Corporation 8040 Dixie Highway Florence KY 41042 United States

The commercialization of proton exchange membrane (PEM) fuel cells depends largely upon the development of PEMs whose properties are enhanced over current perfluorinated sulfonic acid PEMs. Understanding how a PEM's molecular weight and morphology affect its relevant performance properties is essential to this effort. Changes in molecular weight were found to have little effect on the phase separated morphologies, water uptake, and proton conductivities of random copolymers. Changes in block length, however, have a pronounced effect on multiblock copolymers, affecting surface and bulk morphologies, water uptake, proton conductivity, and hydrolytic stability, suggesting that multiblock copolymer PEM properties may be optimized by changes in morphology. © 2010 American Chemical Society.

关键词： Proton conductivity

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Ogden Material Calibration via Magnetic Resonance Cartography, Parameter Sensitivity, and Variational System Identification

arXiv

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arXiv 2022年

作者： Nikolov, Denislav P. Srivastava, Siddhartha Abeid, Bachir A. Scheven, Ulrich M. Arruda, Ellen M. Garikipati, Krishna Estrada, Jonathan B. Department of Mechanical Engineering University of Michigan United States Department of Biomedical Engineering University of Michigan United States Program in Macromolecular Science and Engineering University of Michigan United States Department of Mathematics University of Michigan United States Michigan Institute for Computational Discovery and Eng. University of Michigan United States

Contemporary material characterisation techniques that leverage deformation fields and the weak form of the equilibrium equations face challenges in the numerical solution procedure of the inverse characterisation problem. As material models and descriptions differ, so too must the approaches for identifying parameters and their corresponding mechanisms. The widely-used Ogden material model can be comprised of a chosen number of terms of the same mathematical form, which presents challenges of parsimonious representation, interpretability, and stability. Robust techniques for system identification of any material model are important to assess and improve experimental design, in addition to their centrality to forward computations. Using fully 3D displacement fields acquired in silicone elastomers with our recently-developed magnetic resonance cartography (MR-u) technique on the order of > 20, 000 points per sample, we leverage PDE-constrained optimisation as the basis of variational system identification of our material parameters. We incorporate the statistical F-test to maintain parsimony of representation. Using a new, local deformation decomposition locally into mixtures of biaxial and uniaxial tensile states, we evaluate experiments based on an analytical sensitivity metric, and discuss the implications for experimental design. © 2022, CC BY-NC-ND.

关键词： Inverse problems

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Development of concentrated strain based deployable truss structures

Development of concentrated strain based deployable truss st...

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47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

作者： Pollard, Eric L. Murphey, Thomas W. Mejia-Ariza, Juan M. CSA Engineering Inc. Albuquerque NM 87123-3831 United States Air Force Research Laboratory Albuquerque NM 87117-5776 United States Virginia Polytechnic Institute and State University Blacksburg VA 24061-0344 United States CSA Engineering Inc. 1451 Innovation Pkwy Albuquerque NM 87123-3831 United States AIAA Space Vehicles Directorate 3550 Aberdeen Ave. SE Albuquerque NM 87117- 5776 United States Macromolecular Science and Engineering Program 2018 Hahn Hall Blacksburg VA 24061-0344 United States

ISBN: (纸本)1563478080

The objective of this research is lo develop a novel, deployable hierarchical truss architecture composed of extruded carbon liber reinforced plastic (CFRP) rod and shape memory alloy (SMA) flexure elements;this structural system is representative of a concentrated, material deformation based deployable architecture. The scope of this study encompasses applying fundamental principles of rational truss design, relevant to all deployable structures, first to prove the concept at the individual element level, then to design the packaging kinematics, and finally, evaluate and scale the global performance of the system. Aspects of the architecture for tackle to further develop the truss concept, including manufacturing technology, experimental analysis, and the deployment scheme, will be reported in manuscripts to appear. Technology addressed through this research is intended to foster and mature successive large, launch-packaged concentrated strain structures. Copyright © 2006 by the American Institute of Aeronautics and Astronautics, Inc.

关键词： Trusses

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Manufacture and experimental analysis of a concentrated strain based deployable truss structure

Manufacture and experimental analysis of a concentrated stra...

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47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

作者： Mejia-Ariza, Juan M. Murphey, Thomas W. Pollard, Eric L. Virginia Polytechnic Institute and State University Blacksbury VA 24061-0344 United States Air Force Research Laboratory Albuquerque NM 87117-5776 United States CSA Engineering Inc. Albuquerque NM 87123-3345 United States Macromolecular Science and Engineering Program 2018 Halm Hall Blacksburg VA 24061-0344 United States Space Vehicles Directorate 3550 Aberdeen Ave. SE Albuquerque NM 87117-5776 United States AIAA CSA Engineering Inc. 1600 Eubank Blvd. SE Albuquerque NM 87123-3345 United States

ISBN: (纸本)1563478080

A truss structure was built and tested to advance deployable structures technology based on the concentrated strain approach, In 3rd order hierarchy systems, this architecture has the potential to provide a 10 fold improvement in mass efficiency, and demonstrate a linear compaction ratio that is five times better than current technology. A 101.6 cm x 12.7 cm x 12.7 cm test article was fabricated, and a buckling test and analysis was performed. The total mass of the deployable truss structure was 28 grams. This structure was constructed of piecewise constant cross section elements. One of the components consisted of high-modulus pull-truded carbon fiber rods (CFRs) for the majority of the length, The other components were compliant flexure joints made of Nitinol NiTi, a shape memory alloy (SMA) capable of a repeatable superelastic strain of 5.0% at either boundary. The results of this research provide a contribution to the deployable structures science by improving the compaction ratio and the mass efficiency of deployable structures without decreasing the truss performance limits.

关键词： Trusses

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Slenderness Ratio and Material Optimization of an Impact-Resistant 2d Auxetic Lattice

SSRN

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SSRN 2024年

作者： Zhai, Xuedong Heye-Smith, Karina Mao, Xiaoming Arruda, Ellen M. Department of Mechanical Engineering University of Michigan Ann ArborMI United States Department of Physics University of Michigan Ann ArborMI United States Department of Biomedical Engineering University of Michigan Ann ArborMI United States Program in Macromolecular Science and Engineering University of Michigan Ann ArborMI United States

It is well known that armor prevents failures of behind-armor targets by reducing the force in an impact event and thereby providing protection under certain impact events. However, the kinetic energy associated with an impact, often underappreciated in impact events, can be as fatal as the force by causing relative motion in the target and destructive damage as a consequence. Therefore, efficient protection gear and packaging should be lightweight and good at force reduction as well as energy mitigation. Although auxetic lattices have been studied as lightweight alternatives for force reduction, simultaneous optimization of force reduction and energy dissipation in impact mitigation via geometric and material choices for auxetic lattices has not been addressed. In the present study, we show that a 2D auxetic lattice with an optimized slenderness ratio of the struts that comprise the lattice and optimized elastic and visco-elastic material properties can not only reduce the transmitted peak force but also mitigate the energy significantly. A multi-step optimization method using Finite Element (FE) analysis and a verification procedure via impact experiments are described by which an optimal design of the auxetic lattice can be achieved by simultaneously considering both peak force and energy mitigation. © 2024, The Authors. All rights reserved.

关键词： Armor

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Facile Fabrication of Conductive Paper-based Materials from Tunicate Cellulose Nanocrystals and Polydopamine-decorated Graphene Oxide

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Paper And Biomaterials 2018年第4期3卷 19-25页

作者： XiaoZhou Ma YaoYao Chen Peter R. Chang Jin Huang School of Chemistry and Chemical Engineering Joint International Research Laboratory of Bio-mass-Based Macromolecular Chemistry and Materials Southwest University Chongqing 400715 China School of Chemistry Chemical Engineering and Life Sciences Wuhan University of Technology Wuhan Hubei Province 430070 China Bioproducts and Bioprocesses National Science Program Agriculture and Agri-Food Canada 107 Science Place Saskatoon SK S7N 0X2 Canada

Conductive papers made from graphene and its derivatives are important for the development of electronic devices; however, elastomer-based matrices usually make it difficult for the conductive sheets to form continuous conductive networks. In this work, we used tunicate-derived cellulose nanocrystals （TCNC） instead of traditional elastomers as the matrix for polydopamine （PDA）-coated and reduced graphene oxide （GO） to prepare conductive paper, which, at a low concentration, were better for the formation of conductive networks from conductive sheets. It was found that the Young’s modulus of the conductive paper produced via this strategy reached as high as 7 GPa. Meanwhile, owing to the partial reduction of GO during the polymerization of dopamine, the conductivity of the conductive paper reached as high as 1.3×10-5 S/cm when the PDA-coated GO content was 1 wt%, which was much higher than the conductivity of pure GO （-4.60×10-8 S/cm）. This work provides a new strategy for preparing environmentally friendly conductive papers with good mechanical properties and low conductive fller content, which may be used to produce high-performance, low-cost electronic devices.

关键词： conductive paper tunicate cellulose nanocrystal graphene oxide polydopamine coating casting paper

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Review of Cellulose Nanocrystal-based Fluorophore Materials and Their Application in Metal Ion Detection

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Paper And Biomaterials 2018年第4期3卷 45-61页

作者： Ya Wang Alain Dufresne Peter R. Chang XiaoZhou Ma Jin Huang School of Chemistry and Chemical Engineering Joint International Research Laboratory of Biomass-Based Macromolecular Chemistry and Materials Southwest University Chongqing 400715 China Université Grenoble Alpes CNRS Grenoble INP LGP2 F-38000 Grenoble France Bioproducts and Bioprocesses National Science Program Agriculture and Agri-Food Canada 107 Science Place Saskatoon SK S7N0X2 Canada

Cellulose nanocrystals （CNCs）, a unique and promising natural material extracted from native cellulose, have attracted considerable attention owing to their physical properties and special surface chemistry. This review focuses on chemical conjugation strategies that can be used for preparation of ？uorescent-molecule labeled CNCs and the development of biomaterials. Furthermore, their application in the detection of metal ions and future development prospects are discussed. We hope to provide a clear view of the strategies for surface fluorescent modifcation of CNCs and their application in detection of metal ions.

关键词： fluorescent cellulose nanocrystals detection of metal ions sensors optical imaging biomaterial

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Synthesis and microstructural characterization of POSS-based triblock copolymers prepared using atom transfer radical polymerization

American Chemical Society, Polymer Preprints, Division of Po...

引用

American Chemical Society, Polymer Preprints, Division of Polymer Chemistry 2000年第1期41卷 582-583页

作者： Mather, Patrick T. Chun, Seung B. Pyun, Jeffrey Matyjaszewski, Krzysztof Jeon, Hong G. Polymer Program Institute of Materials Science University of Connecticut Storrs CT 06269-3136 United States Ctr. for Macromolecular Engineering Department of Chemistry Carnegie Mellon University 4400 Fifth Avenue Pittsburgh PA 15213 United States Systran Corp. AFRL/MLBP Wright Patterson AFB Dayton OH 45433-7750 United States

A polyhedral silsesquioxane (POSS)-methacrylate and poly(n-butyl acrylate) triblock copolymer (poly(MA-POSS)-b-BA-b-(MA-POSS)) prepared by atom transfer radical polymerization (ATRP) were synthesized and characterized. The molecular weight and composition of the triblock copolymer was determined from size exclusion chromatography and H NMR spectroscopy. The study aims to develop an understanding of the thermoplastic elastomeric properties as influenced by hard-block interactions and nanometer-scale organization in the materials.

关键词： Block copolymers

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A microfluidic device for separating motile sperm from nonmotile sperm via inter-streamline crossings

A microfluidic device for separating motile sperm from nonmo...

引用

International Conference on Microtechnologies in Medicine and Biology

作者： B. Cho T. Schuster X. Zhu D. Chang G.D. Smith S. Takayama Department of Biomedical Engineering University of Michigan Ann Arbor USA Department of Urology University of Michigan Ann Arbor USA Department of Chemical Engineering University of Michigan Ann Arbor USA Department of Urology Department of Obstetrics & Gynecology Department of Physiology Reproductive Sciences Program University of Michigan Ann Arbor USA Macromolecular Science and Engineering University of Michigan Ann Arbor USA

In vitro fertilization using small amounts of cryopreserved sperm would benefit from efficient microscale methods to sort "healthy" motile sperm from nonmotile ones. This paper describes a microfluidic system with embedded reservoirs that sorts sperm based on the ability of motile sperm to move out of their initial streamlines in a laminar fluid stream. The device has horizontally oriented sample inlet and outlet reservoirs with different relative heights that serve the dual purpose of also being a pumping system that pumps fluids by hydrostatic pressure and surface tension. Sperm sorting is necessary for cryopreservation and intracytoplasmic sperm injection of sperm from men with low viable sperm counts. Since they have few viable sperm, it is difficult to obtain the sperm in an efficient manner using current procedures.

关键词： Microfluidics Sorting Fluid flow Biomedical engineering Reservoirs Pumps Cancer Diseases Microorganisms Humans

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A route to hierarchical assembly of colloidal diamond

arXiv

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arXiv 2021年

作者： Zhou, Yuan Cersonsky, Rose K. Glotzer, Sharon C. Department of Chemical Engineering University of Michigan Ann ArborMI48109 United States Macromolecular Science and Engineering Program University of Michigan Ann ArborMI48109 United States Laboratory of Computational Science and Modelling STI Ècole Polytechnique Fèdèrale de Lausanne Lausanne1015 Switzerland Biointerfaces Institute University of Michigan Ann ArborMI48109 United States

Photonic crystals, appealing for their ability to control light, are constructed by periodic regions of different dielectric constants. Yet, the structural holy grail in photonic materials, diamond, remains challenging to synthesize at the colloidal length scale. Here we explore new ways to assemble diamond using modified gyrobifastigial (mGBF) nanoparticles, a shape that resembles two anti-aligned triangular prisms. We investigate the parameter space that leads to the self-assembly of diamond, and we compare the likelihood of defects in diamond self-assembled via mGBF vs. the nanoparticle shape that is the current focus for assembling diamond, the truncated tetrahedra. We introduce a potential route for realizing mGBF particles by dimerizing triangular prisms using attractive patches, and we report the impact of this superstructure on the photonic properties. Copyright © 2021, The Authors. All rights reserved.

关键词： Diamonds

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