14 results on '"Hreha, R.D."'
Search Results
2. Variable Shape Tooling for Composite Manufacturing: A Systematic Review.
- Author
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Neumann, Fabian
- Subjects
SHAPE memory polymers ,MANUFACTURING processes ,PRESSURE vessels ,ECOLOGICAL assessment ,AIR ducts ,ACTIVE learning - Abstract
The choice of material, manufacturing process, and molding tool significantly affects the quality, environmental impact, and cost efficiency of composite components. Producing one-piece hollow profiles with smooth inner surfaces and undercuts presents major challenges for conventional mold concepts. There is yet no thorough review of shape-variable mandrels in composite manufacturing to be found in the literature. This paper provides an overview of research on shape memory polymers and other shape-variable materials used in tooling applications for composite manufacturing. This work covers shape memory, heat shrink, and other deformable tooling concepts that enable the production of one-piece Type V pressure vessels, air intake ducts, or curved struts and tubes. A systematic literature review in combination with a state-of-the-art open-source active learning tool ASReview is conducted. Fifteen relevant studies were identified. Research on shape-variable tooling is mainly conducted by three research groups in the USA and the PRC. The tooling is mostly made of unreinforced thermosets, especially styrene-based ones. Thermoplastic resins are less common, and reinforcements limit the usable elongation in the temporary shape. The shape variability is either a shape memory and/or a softening process, which, in all studies, is activated by heating. Release agents are widely used to ease demolding. No ecological or economical assessment of the manufacturing methods was conducted in the reviewed studies. Three fields for further research that could be identified are as follows: (1) thorough ecological end economical assessment of shape-variable mandrels in comparison with conventional tooling; (2) thermoplastic shape memory polymer mandrels; and (3) further investigation of simulation capabilities for shape memory mandrels. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Shape Memory Polymers as Smart Materials: A Review.
- Author
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Dayyoub, Tarek, Maksimkin, Aleksey V., Filippova, Olga V., Tcherdyntsev, Victor V., and Telyshev, Dmitry V.
- Subjects
SMART materials ,SHAPE memory polymers ,POLYMER liquid crystals ,SHAPE memory effect ,POLYMER structure ,LIGHT transmission - Abstract
Polymer smart materials are a broad class of polymeric materials that can change their shapes, mechanical responses, light transmissions, controlled releases, and other functional properties under external stimuli. A good understanding of the aspects controlling various types of shape memory phenomena in shape memory polymers (SMPs), such as polymer structure, stimulus effect and many others, is not only important for the preparation of new SMPs with improved performance, but is also useful for the optimization of the current ones to expand their application field. In the present era, simple understanding of the activation mechanisms, the polymer structure, the effect of the modification of the polymer structure on the activation process using fillers or solvents to develop new reliable SMPs with improved properties, long lifetime, fast response, and the ability to apply them under hard conditions in any environment, is considered to be an important topic. Moreover, good understanding of the activation mechanism of the two-way shape memory effect in SMPs for semi-crystalline polymers and liquid crystalline elastomers is the main key required for future investigations. In this article, the principles of the three basic types of external stimuli (heat, chemicals, light) and their key parameters that affect the efficiency of the SMPs are reviewed in addition to several prospective applications. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
4. Review on the Functional Determinants and Durability of Shape Memory Polymers.
- Author
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Pretsch, Thorsten
- Subjects
SHAPE memory alloys ,BIODEGRADATION ,THERMOSETTING composites ,HIBERNATION ,LUBRICATION & lubricants ,ULTRAVIOLET radiation - Abstract
Shape memory polymers (SMP) belong to the class of stimuli-responsive materials and have generated significant research interest. Their capability to retain an imposed, temporary shape and to recover the initial, permanent shape upon exposure to an external stimulus depends on the "functional determinants", which in simplistic terms, can be divided into structural/morphological and processing/environmental factors. The primary aim of the first part of this review is to reflect the knowledge about these fundamental relationships. In a next step, recent advances in shape memory polymer composites are summarized. In contrast to earlier reviews, studies on the impairment of shape memory properties through various factors, such as aging, compression and hibernation, lubricants, UV light and thermo-mechanical cycling, are extensively reviewed. Apart from summarizing the state-of-the-art in SMP research, recent progress is commented. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
5. Charge-Transfer Interactions in Organic Functional Materials.
- Author
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Hsin-Chieh Lin and Bih-Yaw Jin
- Subjects
PHOTODIODES ,QUANTUM theory ,SOLAR cells ,SOLID state chemistry ,MOLECULES ,POLYENES - Abstract
Our goal in this review is three-fold. First, we provide an overview of a number of quantum-chemical methods that can abstract charge-transfer (CT) information on the excited-state species of organic conjugated materials, which can then be exploited for the understanding and design of organic photodiodes and solar cells at the molecular level. We stress that the Composite-Molecule (CM) model is useful for evaluating the electronic excited states and excitonic couplings of the organic molecules in the solid state. We start from a simple polyene dimer as an example to illustrate how interchain separation and chain size affect the intercahin interaction and the role of the charge transfer interaction in the excited state of the polyene dimers. With the basic knowledge from analysis of the polyene system, we then study more practical organic materials such as oligophenylenevinylenes (OPV
n ), oligothiophenes (OTn ), and oligophenylenes (OPn ). Finally, we apply this method to address the delocalization pathway (through-bond and/or through-space) in the lowest excited state for cyclophanes by combining the charge-transfer contributions calculated on the cyclophanes and the corresponding hypothetical molecules with tethers removed. This review represents a step forward in the understanding of the nature of the charge-transfer interactions in the excited state of organic functional materials. [ABSTRACT FROM AUTHOR]- Published
- 2010
- Full Text
- View/download PDF
6. Palladium-catalyzed amination in the synthesis of polyazamacrocycles.
- Author
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Beletskaya, I. P., Averin, A. D., Bessmertnykh, A. G., Denat, F., and Guilard, R.
- Subjects
ORGANIC synthesis ,PALLADIUM ,ALIPHATIC compounds ,AMINES ,MACROCYCLIC compounds - Abstract
The review describes palladium-catalyzed amination of acyclic di- and polyamines with aryl halides with a view to reveal general relations holding in this process. Conditions for the synthesis of macrocycles via catalytic diamination of 1,2- and 1,3-dibromobenzenes, 1,3-dichloro-2-bromobenzene, 2,6- and 3,5-dibromopyridines, 3,3′- and 4,4′-dibromobiphenyls, 2,7-dibromonaphthalene, 1,8- and 1,5-dichloroanthracene, 1,8- and 1,5-dichloroanthraquinones, and bis(haloaryl) derivatives of cyclen, cyclam, and cholanediol are discussed. The possibility for palladium-catalyzed arylation of cyclic polyamines has been demonstrated. Specificity of macrocyclization processes and relations between the yield of macrocycles and the nature of initial compounds are considered, and data on the synthesis of cyclic dimers are given. Applications of polyazamacroheterocycles as optical sensors for metal cations are described using as examples macrocyclic compounds derived from 1,8-disubstituted anthraquinone. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
7. Post-Polymerization Modification of Ring Opening Metathesis Polymerization (ROMP)-Derived Materials Using Wittig Reactions.
- Author
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Duty, Ryan and Hobbs, Christopher E.
- Subjects
WITTIG reaction ,OLEFINATION reactions ,POLYMERIZATION ,RING formation (Chemistry) ,PHOSPHONIUM compounds - Abstract
This communication describes our recent efforts to utilize Wittig olefination reactions for the post-polymerization modification of polynorbornene derivatives prepared through ring opening metathesis polymerization (ROMP). Polymerizing α-bromo ester-containing norbornenes provides polymers that can undergo facile substitution with triphenylphosphine. The resulting polymeric phosphonium salt is then deprotonated to form an ylide that undergoes reaction with various aryl aldehydes in a one-pot fashion to yield the respective cinnamates. These materials can undergo further modification through photo-induced [2 + 2] cycloaddition cross-linking reactions. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
8. Advances in Nonlinear Dynamics, Volume III : Proceedings of the Third International Nonlinear Dynamics Conference (NODYCON 2023)
- Author
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Walter Lacarbonara and Walter Lacarbonara
- Subjects
- Plasma waves, Multibody systems, Vibration, Mechanics, Applied, Dynamics, Nonlinear theories, System theory
- Abstract
This third of three volumes presents papers from the third series of NODYCON to be held in June of 2023. The conference papers reflect a broad coverage of topics in nonlinear dynamics, both traditionally placed in established streams of research as well as they stand as newly explored and emerging venues of research. These include• Multi-scale dynamics: multiple time/space scales, large system dynamics• Experimental dynamics: benchmark experiments, experimental methods,instrumentation techniques, measurements in harsh environments, experimentalvalidation of nonlinear models• Reduced-order modeling: center manifold reduction, nonlinear normal modes, normalforms• Systems with time and/or space delays• Nonlinear interactions in multi-dof systems: parametric vibrations, multiple external andautoparametric resonances.• Computational techniques: efficient algorithms, use ofsymbolic manipulators, integrationof symbolic manipulation and numerical methods, use of parallel processors.• Nonlinear system identification: parametric/nonparametric identification, data-drivenidentification• Multibody dynamics: rigid and flexible multibody system dynamics, impact and contactmechanics, tire modeling, railroad vehicle dynamics, biomechanics applications,computational multibody dynamics• Fluid/structure interaction• Nonlinear wave propagation in discrete and continuous media
- Published
- 2024
9. Smart Stimuli-Responsive Polymers, Films, and Gels
- Author
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Liang Hu, Yongfeng Gao, Michael J. Serpe, Liang Hu, Yongfeng Gao, and Michael J. Serpe
- Abstract
Smart Stimuli-Responsive Poymers, Films, and Gels Discover the most important developments in synthesis, simulation, and applications of a fascinating compound class There exist a range of natural materials that respond to environmental changes by altering their physical or chemical properties, known as stimuli-responsive polymers, these substances are responsive to light, temperature, pressure, and more. The study of these so-called “smart” polymers is essential to a range of application fields, many of which have generated cutting-edge research in recent decades. A comprehensive introduction to the subject is therefore well-timed Smart Stimuli-Responsive Polymers, Films, and Gels provides an introduction to these polymers and their applications. It includes producing these polymers through synthetic approaches, simulating their responses to different stimuli, and applying these materials in different industries and research capacities. Written to serve the requirements of advanced students and senior researchers alike, this timely work will drive years of research in this vital field. In Smart Stimuli-Responsive Polymers, Films, and Gels readers will also find: Treatment of mechanoresponsive, photoresponsive, and ionizing-radiation responsive polymers Applications in emerging fields such as sensors, biomedicine, catalysis, and more Interdisciplinary research into the properties and responses of these vital compounds Smart Stimuli-Responsive Polymers, Films, and Gels promises to become a seminal work for chemists, materials scientists, and industrial researchers seeking to incorporate these materials into a variety of industrial and research areas.
- Published
- 2022
10. Handbook of Thermoset Plastics
- Author
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Hanna Dodiuk and Hanna Dodiuk
- Abstract
Handbook of Thermoset Plastics, Fourth Edition provides complete coverage of the chemical processes, manufacturing techniques and design properties of each polymer, along with its applications. This new edition has been expanded to include the latest developments in the field, with new chapters on radiation curing, biological adhesives, vitrimers, and 3D printing. This detailed handbook considers the practical implications of using thermoset plastics and the relationships between processing, properties and applications, as well as analyzing the strengths and weakness of different methods and applications.The aim of the book is to help the reader to make the right decision and take the correct action on the basis of informed analysis – avoiding the pitfalls the authors'experience has uncovered. In industry, the book supports engineers, scientists, manufacturers and R&D professionals working with plastics. The information included will also be of interest to researchers and advanced students in plastics engineering, polymer chemistry, adhesives and coatings. - Offers a systematic approach, guiding the reader through chemistry, processing methods, properties and applications of thermosetting polymers - Includes thorough updates that discuss current practice and the new developments on biopolymers, nanotechnology, 3D printing, radiation curing and biological adhesives - Uses case studies to demonstrate how particular properties make different polymers suitable for different applications - Covers end-use and safety considerations
- Published
- 2021
11. Basics of Polymers : Materials and Synthesis
- Author
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Muralisrinivasan, Natamai Subramanian and Muralisrinivasan, Natamai Subramanian
- Subjects
- Polymers
- Abstract
Basics of Polymers: Materials and Synthesis is a major investigative tool in the design and synthesis of polymers in the modern academic and industrial fields. Materials and synthesis encompass a wide range of operations such as selection of monomer(s) and polymerization techniques for the synthesis of materials under various operating conditions. The design and synthesis of each process should therefore be based on specific features. This book highlights the diversity of approaches used in understanding polymer synthesis. This book is designed to be used as study materials for students, professionals, and professors that support their wide use on material and synthesis. It emphasizes the value of each relevant synthesis method and polymerization type, rather than complex mechanisms or the history of its development. An area of considerable interest in this book is polymer synthesis in terms of the relationship between the structure and function of monomer(s). This book is also directed toward postgraduate students and practicing engineers who wish to develop polymer synthesis.
- Published
- 2016
12. Dyes and Chromophores in Polymer Science
- Author
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Jacques Lalevée, Jean-Pierre Fouassier, Jacques Lalevée, and Jean-Pierre Fouassier
- Subjects
- Polymer engineering
- Abstract
The design and development of dyes and chromophores have recently attracted much attention in various research fields such as materials, radiation curing, (laser) imaging, optics, medicine, microelectronics, nanotechnology, etc.. In this book, the recent research for the use of dyes and chromophores in polymer science is presented. The interaction of the visible light with the dyes or the selected chromophores is particularly important in different fields (e.g. for photovoltaic, display applications (LED...), laser imaging or laser direct writing, green chemistry with sunlight induced photopolymerization etc...). This book gives an overview of the dyes and chromophores for all the important fields.
- Published
- 2015
13. High Performance Textiles and Their Applications
- Author
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C. Lawrence and C. Lawrence
- Subjects
- Textile fibers, Textile fabrics, Industrial fabrics, Textile fibers--Technological innovations, Textile fabrics--Technological innovations
- Abstract
High performance textiles represent one of the most dynamic sectors of the international textile and clothing industry. With contributions from leading experts in the field, this book provides an important overview of key developments in the field. Chapters cover the use of high performance textiles in such areas as protective clothing, heat and fire protection, medicine, civil engineering and the energy sector. - Reviews various approaches to modelling the geometry, structure and mechanical and physical properties of advanced textile materials - Evaluates novel surface treatments involving plasma and laser technologies for a range of high performance textiles - Focuses on textiles for specific purposes, with chapters devoted to textiles for heat and fire protection, wound care, industrial filtration, geotextiles, civil engineering and sustainable energy applications
- Published
- 2014
14. Advanced Fibre-Reinforced Polymer (FRP) Composites for Structural Applications
- Author
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Jiping Bai and Jiping Bai
- Subjects
- Building materials, Polymeric composites, Fibrous composites
- Abstract
Advanced fibre-reinforced polymer (FRP) composites have become essential materials for the building of new structures and for the repair of existing infrastructure. Advanced fibre-reinforced polymer (FRP) composites for structural applications provides an overview of different advanced FRP composites and the use of these materials in a variety of application areas.Part one introduces materials used in the creation of advanced FRP composites including polyester, vinylester and epoxy resins. Part two goes on to explore the processing and fabrication of advanced FRP composites and includes chapters on prepreg processing and filament winding processes. Part three highlights properties of advanced FRP composites and explores how performance can be managed and tested. Applications of advanced FRP composites, including bridge engineering, pipe rehabilitation in the oil and gas industry and sustainable energy production, are discussed in part four.With its distinguished editor and international team of expert contributors, Advanced fibre-reinforced polymer (FRP) composites for structural applications is a technical resource for researchers and engineers using advanced FRP composites, as well as professionals requiring an understanding of the production and properties of advanced FRP composites, and academics interested in this field. - Provides an overview of different advanced FRP composites and the use of these materials in a variety of application areas - Introduces materials used in the creation of advanced FRP composites including polyester, vinylester and epoxy resins - Explores the processing and fabrication of advanced FRP composites and includes chapters on prepreg processing and filament winding processes
- Published
- 2013
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