Old cellulose for new multifunctional networks

Dissertação para obtenção do Grau de Doutor em Ciência e Engenharia de MateriaisCellulose is considered to be the most abundant and renewable natural polymer on earth. It is the main component of plant cells. The exploration of the utility and applications of this material and its derivatives has never stopped since human´s birth. It is well known that cellulose based materials can generate films and fibers, which can be, for instance, produced from cellulosic solutions. The Cellulose rich chemical structure allows different behaviors of the polymer in solution, which is the driving force for diverse films and fibers features. The main goal of this work is the manufacture and characterization of new application of the renewable cellulosic-based materials, which are at the origin of stimuli-responsive and/or functional soft films and fibers. The several materials obtained have in common the main chain cellulose backbone but present different liquid crystalline properties. Firstly rheology coupled to nuclear magnetic resonance techniques (rheo-NMR) were used to characterize a cellulose-water based liquid crystalline solution in order to establish structure/properties relationships, which were the basis to improve the design of films and fibers produced in the framework of this work. The results achieved were at the origin of a paper published in Macromolecules. Then films were produced and due to their structure and enhanced mechanical properties, different applications were realized by producing cellulosic gratings, which mimic the periodic structures that can be found in some petals of plants and a soft cellulose moisture motor was built for the first time. Two manuscripts were published, one related to the grating mimics, in Macromolecular Chemistry and Physics, and the other one dedicated to the mechanical properties and the bending of a cellulosic film controlled by moisture action in Scientific Reports (Nature Publishing Group). Concerning cellulosic fibers, two methods were selected to fabricate micro/nano networks. In order to produce suspended aligned arrays, electrospinning was chosen due to its versatility. On the obtained nano/micro cylinders, nematic and cholesteric droplets were threaded producing necklaces of liquid crystal beads for the first time. The fiber changes not only the topology of the droplet but also distorts its spherical shape to an approximately ellipsoidal droplet. An additional cylindrical surface with planar anchoring along the droplet’s long axis was also added. Designing nematic and cholesteric liquid crystal microdroplets on thin long threads opened new routes to produce fiber waveguides decorated with complex microresonators. Two Soft Matter scientific papers were published based on this work (One was chosen as the cover of that issue). Finally, nano-fibers produced by cellulose acid hydrolises were prepared and a new electro-optical sensor was built up and characterized and the results published in Liquid Crystals journal. Throughout this work Landau-de-Gennes theory was used in order to interpret and understand some of the experimental results achieved.Portuguese Science and Technology Foundation - SFRH/BD/63574/2009, PTDC/CTM/099595/2008, PTDC/CTM-POL/1484/2012, PTDC/CTM/101776/2008, PTDC/FIS/110132/2009, and PEst- C/CTM/LA0025/2011 (Strategic Project - LA 25-2011-2012

Cellulose Filaments for Responsive and Functional Materials

Cellulosic filaments, found in plants, are crucial structural elements for their survival and are a great source of inspiration to obtain new functional materials. The work performed out in this thesis aimed for the isolation, physical characterization, study of the morphology and shape, as well as the mechanical behaviour of cellulosic filaments obtained from the leaves of Agapanthus africanus and Ornithogalum thyrsoides and from the filaments that form the ribbons existing on the awns of the Erodium plants. These cellulosic filaments and filament networks were chosen due to the fundamental role that they play in the plant kingdom and their ability to change shape in the presence of an external stimuli. The study of the chosen systems served as an inspiration for the preparation and production of new membranes formed by non-woven networks of micro/nano filaments. A prototype, which allows for the selective removal of oil micro droplets from aqueous emulsions, was developed. This dissertation begins with a general introduction, based on two review papers, which the author of this thesis is the first author, in which the main concepts used in the following chapters are addressed and interconnected. The original part of the work is in chapters II, III and IV. In chapter II, the study of microfilaments from the leaves tracheary of two plants, Agapanthus africanus and Ornithogalum thyrsoides, is made. These microfilaments belong to plants of the same order and have identical shapes (left helices), chemical composition and skeletons, but different mechanical properties. For the first time, micrometric droplets of a nematic liquid crystal were used as sensors to reveal the morphology of the filaments. In order to obtain quantitative characteristics on the surface of the microfilaments, photos of the textures of pierced droplets were obtained by Polarized Optical Microscopy (POM). These textures were compared with simulated optical microphotographs obtained by numerical modelling for the nematic droplets. Homeotropic anchoring at the air, and different anchoring conditions, at the interfaces with the filaments were considered for the nematic structure. This study allowed the establishment of relationships between the physical properties/morphology of the filaments and to determine their interactions with other filaments and with the environment. In chapter III, cellulosic networks existing on dead tissues of the Erodium awns were isolated and characterized. An interesting feature of these cellulosic networks is that they form ribbons that change reversibly the shape in the presence of moisture. When dried these ribbons are right-handed helices, that uncoil remaining taut, in the presence of moisture. The work performed allowed the preparation of helical ribbons that can change the shape from right- to lefthanded helices in the presence of moisture. The behaviour observed was explained using computational simulations, considering filaments that contract and expand asymmetrically. Birefringent transparent ribbons were also isolated. The asymmetric arrangement of cellulosic fibres allows the material to be stimuli-responsive without the use of complicated lithography and intricate deposition techniques, making it suitable for a diverse range of applications, such as the production of intelligent textiles and environmental friendly micro components. In chapter IV, non-woven membranes obtained from cellulosic materials and cellulose nanocrystals were prepared and characterized. Different patterns were designed using the screenprinting technique. The adhesion between the different types of cellulosic fibres was promoted through a heat treatment. The non-woven membranes produced allowed the development of a prototype that selectively removes oil droplets from aqueous emulsions with an efficiency of approximately 80%. Throughout this thesis (chapters II and III), the complexity of the systems increases. The work begins by studying the morphology of a filament and its mechanical behaviour in the presence of other filaments. After a much more complex system, in which anisotropic filament networks, produced by the Erodium plant were addressed. The stimuli-responsive behaviour of these anisotropic networks was investigated after being released by the plant. Based on the understanding of the systems formed by cellulosic filaments, studied in chapters II and III, functional non-woven membranes were produced, printed, and characterized. The non-woven membranes led to the development of a prototype, which allows the selective removal of micro droplets of oil form aqueous emulsions. At the end, a summary of the main scientific results and future work including a technological application, which was developed in the framework of this thesis, are presented.Os filamentos celulósicos, existentes nas plantas, são elementos estruturais cruciais para a sua sobrevivência e fontes de inspiração para a obtenção de novos materiais funcionais. O trabalho realizado nesta tese visou o isolamento, caracterização física, estudo da morfologia e forma, assim como do comportamento mecânico de filamentos celulósicos obtidos a partir das folhas das plantas Agapanthus africanus e Ornithogalum thyrsoides e de filamentos que formam fitas existentes nas hastes da planta Erodium. Estes filamentos e redes de filamentos celulósicos foram escolhidos devido ao papel fundamental que desempenham no reino vegetal e à resposta que podem apresentar na presença de estímulos externos. O estudo dos sistemas escolhidos serviu de inspiração para a preparação e fabrico de novas membranas formadas por redes não tecidas de filamentos micro/nanométricos e o desenvolvimento de um protótipo, que permite a remoção seletiva de microgotas de óleo de emulsões aquosas. Inicia-se com uma introdução de caracter geral, baseada em dois artigos de revisão, dos quais a autora desta tese é primeira autora, na qual se abordam e interligam os conceitos principais, que são utilizados nos capítulos seguintes. A parte original do trabalho reparte-se pelos capítulos II, III e IV. No capítulo II é feito o estudo de microfilamentos existentes nos sistemas vasculares das folhas de duas plantas, Agaphantus africanus e Ornithogalum thyrsoides. Estes microfilamentos pertencem a plantas da mesma ordem e possuem formas (hélices esquerdas), composições químicas e esqueletos idênticos, mas apresentam propriedades mecânicas distintas. Pela primeira vez foram utilizadas gotas micrométricas de um cristal líquido nemático como sensores da morfologia dos filamentos isolados. De modo a obter características quantitativas sobre a superfície dos microfilamentos, fotos de texturas obtidas por microscopia com luz polarizada foram comparadas com microfotografias óticas simuladas a partir de modelação numérica de um meio contínuo das estruturas das gotas nemáticas, com ancoragem homeotrópica na superfície com o ar suspensas nos microfilamentos com diferentes ancoragens. O estudo realizado permitiu estabelecer relações entre as propriedades físicas/morfologia dos filamentos e determinar as suas interações com outros filamentos e com o meio ambiente. No capítulo III foram isoladas e caracterizadas redes celulósicas existentes nas hastes de tecidos mortos da planta Erodium. Uma característica interessante destas redes celulósicas é a de formarem fitas que mudam reversivelmente de conformação na presença de humidade. Quando secas estas fitas são hélices direitas, que na presença de humidade desenrolam para fitas esticadas, sem torção nem flexão. Este trabalho permitiu induzir uma inversão de quiralidade nas fitas que foi explicada pelo uso de simulações computacionais considerando que as fitas contraem e esticam de modo assimétrico. Fitas birrefringentes transparentes também foram isoladas. A disposição assimétrica das fibras celulósicas permite a resposta do material não envolvendo o uso de técnicas complicadas de litografia nem de deposição, podendo ser aplicado, por exemplo, no fabrico de têxteis inteligentes e de microcomponentes amigos do ambiente. No capítulo IV foram preparadas e caracterizadas membranas não tecidas obtidas a partir de soluções de derivados celulósicos e de celulose nano cristalina. Foram desenhadas diferentes geometrias pela utilização da técnica de “screenprinting” e promovida a adesão entre os diferentes tipos de fibras celulósicas através de tratamento térmico. As membranas não tecidas produzidas permitiram o desenvolvimento de um protótipo que remove, de forma seletiva, microgotas de óleo de emulsões aquosas com uma eficiência de cerca de 80%. Ao longo desta tese (capítulo II e III), a complexidade dos sistemas estudados aumenta, isto é, começa-se por estudar a morfologia de um filamento e o seu comportamento mecânico na presença de outros filamentos, para depois se passar para um sistema muito mais complexo em que redes anisotrópicas de filamentos, impressas pela planta Erodium, permitem a resposta a estímulos externos da estrutura formada, mesmo após esta ter abandonado a planta. Tendo por base a compreensão dos sistemas formados por filamentos celulósicos, estudados nos capítulos II e III, foram produzidas, impressas e caracterizadas, no laboratório, membranas funcionais tecidas de filamentos micro/nano celulósicos. As membranas não tecidas originaram o desenvolvimento de um protótipo, que permite a remoção seletiva de micro gotas de óleo existentes em emulsões aquosas. No final é apresentado um sumário dos principais resultados científicos e perspetivas de avanço tecnológico alcançadas por este trabalho

Dynamic digital shearography for on-board robotic non-destructive testing of wind turbine blades

Structural integrity plays a critical role in development of infrastructural construction and support facilities. During the lifespan of most large-scale equipment, condition monitoring and periodic inspection is indispensable for ensuring structural health and evaluation of service condition. Wind turbine blades are the most important component of wind turbines and demands regular inspection to detect defects, which often occur underneath a blade surface. Current methods used to inspect wind turbine blades include to send NDT operators to climb the tower for on-site inspection of the blades’ surface or to dismantle the blades for inspection on the ground. These approaches are time-consuming, costly and pose risks of injury to human inspectors. Thus, it is necessary to develop a technological method for wind turbine blade on-site inspection of wind turbine blades. Digital shearography based on laser interferometry has demonstrated its prominent capability for inspecting composite material which is the main material used in the construction of wind turbine blades. Shearography is a ramification of holography interferometry and is more efficient to be used as a non-destructive testing (NDT) technique owing to its improved robustness and sensitivity to surface displacement. Robotic climbers, on the other hand, have recently drawn significant interest in NDT applications to replace human inspectors in extreme conditions. Thus, this thesis presents investigations into the development of a robotic NDT method using digital shearography for on-site inspection of wind turbine blades. The development of the shearography unit with correlation fringe pattern acquisition and the integration of this unit with the robotic climber adhering to wind turbine blades using vacuum generators are described in this thesis. The successful conduction of the indoor and outdoor trails for the integrated system verifies that shearography holds the ability to be used as an NDT tool for on-site wind turbine blade inspection, and that the climbing robot is able to access most areas of a wind turbine blade and stabilise itself to remove the impact on the shearography of the high frequencies from the climber’s vacuum motor and the low frequencies from the blade swing. Temporal phase shift shearography, and the fast phase map acquisition methods with less steps are evaluated in the thesis. Experiments are performed in lab with phase maps obtained using different algorithms. Apart from the conventional 4 steps and 3 steps phase shift algorithms, the modified 4+1 and 3+1 temporal phase shifting algorithms are developed for more suitability of semi-dynamic inspection by firstly calculating the correlation fringes and followed by the phase map calculations. The results of these modified methods are compared with the conventional 4 steps and 3 steps methods and are shown with equal qualities. Moreover, the reduced steps of phase shifting, i.e., 2+1 phase shifting methods are conducted for semi-dynamic phase map acquisition. It is found that the temporal phase shifting methods are not suitable for dynamic wind turbine blade inspection, however, the fast semi-dynamic temporal phase shift algorithms are able to produce phase maps with lower clarity. Pixelated spatial phase shift shearography is developed to remedy the limitation of temporal phase shift techniques. It adopts a micro-polarization sensor in the complementary metal oxide semiconductor (CMOS) camera, two linear polarizers, and a quarter waveplate as a new arrangement of optical path to replace the piezoelectric transducer stepper as the phase stepper. Three algorithms are introduced based on this novel developed system. Additionally, the site of view is enlarged for upgrading of the system. The development of the pixelated spatial phase shift shearography has mitigated the static processing limitation on temporal phase shift shearography, which caters for the demands of on-site NDT operation. At the same time, it remedies the current real-time shearography system which is not able to produce phase distributions for further quantitative analysis. The new developed pixelated spatial phase shift shearography system is thus more suitable for WTB on board inspection than both conventional and less-steps temporal phase shift shearography system. The field of view enlargement optimisation in the new developed spatial phase shift system indirectly reduces the distance for the inspection process and meanwhile enlarges the site of view, which consequently reduces the weight and structural complexity of the robotic-shearography integration system. The research addresses and resolves the difficulty of on-board wind turbine blade inspection with a novel robotic NDT approach using digital shearography. The approach is significant for real world industrial applications. Moreover, through the temporal and spatial phase shift evaluation, the research proves the feasibility of dynamically obtaining phase maps by the shearography system for further quantitative analysis without using temporal phase shift devices

The NASA SBIR product catalog

The purpose of this catalog is to assist small business firms in making the community aware of products emerging from their efforts in the Small Business Innovation Research (SBIR) program. It contains descriptions of some products that have advanced into Phase 3 and others that are identified as prospective products. Both lists of products in this catalog are based on information supplied by NASA SBIR contractors in responding to an invitation to be represented in this document. Generally, all products suggested by the small firms were included in order to meet the goals of information exchange for SBIR results. Of the 444 SBIR contractors NASA queried, 137 provided information on 219 products. The catalog presents the product information in the technology areas listed in the table of contents. Within each area, the products are listed in alphabetical order by product name and are given identifying numbers. Also included is an alphabetical listing of the companies that have products described. This listing cross-references the product list and provides information on the business activity of each firm. In addition, there are three indexes: one a list of firms by states, one that lists the products according to NASA Centers that managed the SBIR projects, and one that lists the products by the relevant Technical Topics utilized in NASA's annual program solicitation under which each SBIR project was selected

Bioinspired Light Robots from Liquid Crystal Networks

Bioinspired material research aims at learning from the sophisticated design principles of nature, in order to develop novel artificial materials with advanced functionalities. Some of the sophisticated capabilities of biological materials, such as their ability to self-heal or adapt to environmental changes, are challenging to realize in artificial systems. Nevertheless, many efforts have been recently devoted to develop artificial materials with adaptive functions, especially materials which can generate movement in response to external stimuli. One such effort is the field of soft robots, which aims towards fabrication of autonomous adaptive systems with flexibility, beyond the current capability of conventional robotics. However, in most cases, soft robots still need to be connected to hard electronics for powering and rely on complicated algorithms to control their deformation modes. Soft robots that can be powered remotely and are capable of self-regulating function, are of great interest across the scientific community.In order to realize such responsive and adaptive systems, researches across the globe are making constant efforts to develop new, ever-more sophisticated stimuliresponsive materials. Among the different stimuli-responsive materials, liquid crystal networks (LCNs) are the most suited ones to design smart actuating systems as they can be controlled and powered remotely with light and thereby obviate the need for external control circuitry. They enable pre-programable shape changes, hence equipping a single material with multiple actuation modes. In addition to light, they can also be actuated by variety of stimuli such as heat, humidity, pH, electric and magnetic fields etc., or a combination of these. Based on these advantages of LCNs, we seek inspiration from natural actuator systems present in plants and animals to devise different light controllable soft robotic systems.In this thesis, inspired from biological systems such as octopus arm movements, iris movements in eyes, object detection and capturing ability of Venus flytraps and opening and closing of certain nocturnal flowers, we demonstrate several light robots that can be programmed to show pre-determined shape changes. By employing a proper device design, these light robots can even show the characteristics of selfregulation and object recognition, which brings new advances to the field of LCNbased light robots. For instance, octopod light robot can show bidirectional bending owing to alignment programming using a commercial laser projector; artificial iris is a fully light controllable device that can self-regulate its aperture size based on intensity of incident light; the optical flytrap can not only autonomously close on an object coming into its ‘‘mouth’’ but it can also distinguish between different kinds of objects based on optical feedback, and finally, integration of light and humidity responsiveness in a single LCN actuator enables a nocturnal flower-mimicking actuator, which provides an opportunity to understand the delicate interplay between different simultaneously occurring stimuli in a monolithic actuator.We believe that besides providing a deeper understanding on the photoactuation in liquid crystal networks, at fundamental level, our work opens new avenues by providing several pathways towards next-generation intelligent soft microrobots

Small business innovation research. Abstracts of 1988 phase 1 awards

Non-proprietary proposal abstracts of Phase 1 Small Business Innovation Research (SBIR) projects supported by NASA are presented. Projects in the fields of aeronautical propulsion, aerodynamics, acoustics, aircraft systems, materials and structures, teleoperators and robots, computer sciences, information systems, data processing, spacecraft propulsion, bioastronautics, satellite communication, and space processing are covered

JTEC panel on display technologies in Japan

This report is one in a series of reports that describes research and development efforts in Japan in the area of display technologies. The following are included in this report: flat panel displays (technical findings, liquid crystal display development and production, large flat panel displays (FPD's), electroluminescent displays and plasma panels, infrastructure in Japan's FPD industry, market and projected sales, and new a-Si active matrix liquid crystal display (AMLCD) factory); materials for flat panel displays (liquid crystal materials, and light-emissive display materials); manufacturing and infrastructure of active matrix liquid crystal displays (manufacturing logistics and equipment); passive matrix liquid crystal displays (LCD basics, twisted nematics LCD's, supertwisted nematic LCD's, ferroelectric LCD's, and a comparison of passive matrix LCD technology); active matrix technology (basic active matrix technology, investment environment, amorphous silicon, polysilicon, and commercial products and prototypes); and projection displays (comparison of Japanese and U.S. display research, and technical evaluation of work)

NASA Tech Briefs, January 2012

Contents of this issue are: (1) Energy-Based Tetrahedron Sensor for High-Temperature, High-Pressure Environments (2) Handheld Universal Diagnostic Sensor (3) Large-Area Vacuum Ultraviolet Sensors (4) Fiber Bragg Grating Sensor System for Monitoring Smart Composite Aerospace Structures (5) Health-Enabled Smart Sensor Fusion Technology (6) Extended-Range Passive RFID and Sensor Tags (7) Hybrid Collaborative Learning for Classification and Clustering in Sensor Networks (8) Self-Healing, Inflatable, Rigidizable Shelter (9) Improvements in Cold-Plate Fabrication (10) Technique for Radiometer and Antenna Array Calibration - TRAAC (11) Real-Time Cognitive Computing Architecture for Data Fusion in a Dynamic Environment (12) Programmable Digital Controller (13) Use of CCSDS Packets Over SpaceWire to Control Hardware (14) Key Decision Record Creation and Approval Module (15) Enhanced Graphics for Extended Scale Range (16) Debris Examination Using Ballistic and Radar Integrated Software (17) Data Distribution System (DDS) and Solar Dynamic Observatory Ground Station (SDOGS) (18) Integration Manager (19) Eclipse-Free-Time Assessment Tool for IRIS (20) Automated and Manual Rocket Crater Measurement Software (21) MATLAB Stability and Control Toolbox Trim and Static Stability Module (22) Patched Conic Trajectory Code (23) Ring Image Analyzer (24) SureTrak Probability of Impact Display (25) Implementation of a Non-Metallic Barrier in an Electric Motor (26) Multi-Mission Radioisotope Thermoelectric Generator Heat Exchangers for the Mars Science Laboratory Rover (27) Uniform Dust Distributor for Testing Radiative Emittance of Dust-Coated Surfaces (28) MicroProbe Small Unmanned Aerial System (29) Highly Stable and Active Catalyst for Sabatier Reactions (30) Better Proton-Conducting Polymers for Fuel-Cell Membranes (31) CCD Camera Lens Interface for Real-Time Theodolite Alignment (32) Peregrine 100-km Sounding Rocket Project (33) SOFIA Closed- and Open-Door Aerodynamic Analyses (34) Sonic Thermometer for High-Altitude Balloons (35) Near-Infrared Photon-Counting Camera for High-Sensitivity Observations (36) Integrated Optics Achromatic Nuller for Stellar Interferometry (37) High-Speed Digital Interferometry (38) Ultra-Miniature Lidar Scanner for Launch Range Data Collection (39) Shape and Color Features for Object Recognition Search (40) Explanation Capabilities for Behavior-Based Robot Control (41) A DNA-Inspired Encryption Methodology for Secure, Mobile Ad Hoc Networks (42) Quality Control Method for a Micro-Nano-Channel Microfabricated Device (43) Corner-Cube Retroreflector Instrument for Advanced Lunar Laser Ranging (44) Electrospray Collection of Lunar Dust (45) Fabrication of a Kilopixel Array of Superconducting Microcalorimeters with Microstripline Wiring Spacecraft Attitude Tracking and Maneuver Using Combined Magnetic Actuators (46) Coherent Detector for Near-Angle Scattering and Polarization Characterization of Telescope Mirror Coating

NASA patent abstracts bibliography: A continuing bibliography. Section 1: Abstracts (supplement 34)

Abstracts are provided for 124 patents and patent applications entered into the NASA scientific and technical information systems during the period July 1988 through December 1988. Each entry consists of a citation, an abstract, and in most cases, a key illustration selected from the patent or patent application