Translucent Silica Aerogel

Silica translucent aerogels are unique materials able to improve the thermal insulation performance of buildings without compromising daylight transmission. The aim of the book is to give a general overview on state of the art research on translucent aerogels and their applications in buildings and to provide a data set about thermal and physical properties, useful in buildings' energy performance simulation and design.Silica aerogels are nanostructured solid materials made of approximately 96% air and 4% silica. They show a thermal conductivity in the 0.012-0.020 W/mK range and excellent optical properties, especially visible transmission. They come in granular and monolithic form. Granular aerogels are relatively easy to produce and less expensive than monolithic panes, but show worse optical and thermal performance. Monolithic aerogels enable vision through the material, but their fabrication process is not developed at an industrial scale.The book collects the contributions of experts in the field of translucent aerogels from all over the world. The contents of the eight chapters are detailed as follows:Chapter 1 is the contribution from Union College, Schenectady (USA). The chapter reviews the chemical approaches to silica wet gels preparation, the drying methods used to yield monoliths, and the challenges and limitations associated with its production.Chapter 2 is a contribution from EMPA, Dübendorf (Switzerland). It is a review of current state of the art research on silica aerogel granulate production, including raw materials selection, hydrophobization strategies, and drying methodologies. Chapter 3 is a contribution from Takenaka Corporation, Tokyo (Japan). The main techniques for the optical properties evaluation are described and data are provided. An original application of translucent aerogels in buildings and future research topics are also proposed.Chapter 4 is a contribution from Recep Tayyip Erdogan University, Rize and Ataturk University, Erzurum (Turkey). A review of the thermal properties of aerogels is provided, highlighting their better performance when compared to conventional and superinsulation materials.Chapter 5 is a contribution from the University of Perugia, Perugia (Italy). The acoustic properties of both granular and monolithic systems are investigated. For example, the influence of granule size and layer thickness that is deepened for granular aerogels is discussed, while for the monolithic form, the little data that is currently available is reported on. Chapter 6 is a contribution from the University of Tuscia, Viterbo (Italy) and Buro Happold Ltd, London (UK). It is focused on Life Cycle Assessment of silica aerogel, showing the research challenges in understanding its environmental impact, lower than the one of conventional thermal insulating glazing systems.Chapter 7 is a contribution from the University of Lyon and INSA-Lyon, Lyon (France). An overview of measurement methods and modeling tools available in literature is provided and a summary of the main mechanical properties of both monolithic and granular aerogels is reported on.Chapter 8 is a contribution from the Norwegian University of Science and Technology, Trondheim and SINTEF, Trondheim (Norway). Authors present their experimental investigations on various aerogel systems in different building envelopes (new aerogel glass material, aerogel-incorporated concrete, and so forth).

During my professional career, I developed a strong interest in sol-gel technology, and worked on both xerogel and aerogel systems. My fascination with aerogels has driven me to explore their commercial potential, which is currently an important component of my company's business plan. Together with my co-workers, I have also worked on the preparation of controlled PZT and silica xerogels as well as thin film coatings of metals by the sol-gel technology, These experiences convinced me of the tremendous potentials of this technology. A conviction that is shared by many scientists, engineers, and business leaders around the globe. Many sol-gel derived products are already articles of commerce. However, to expand the commercial potential of sol-gel technology, two challenges must be met: (1) the quality of sol-gel derived products must continue to meet or exceed the quality of competing products, (2) the production cost of sol-gel products (specially aerogels) must continued to decline. A key to lowering the costs of sol-gel products is finding inexpensive precursors.

This Encyclopedia begins with an introduction summarizing itsscope and content. Glassmaking; Structure of Glass, GlassPhysics,Transport Properties, Chemistry of Glass, Glass and Light,Inorganic Glass Families, Organic Glasses, Glass and theEnvironment, Historical and Economical Aspect of Glassmaking,History of Glass, Glass and Art, and outlinepossible newdevelopments and uses as presented by the best known people in thefield (C.A. Angell, for example). Sections and chapters arearranged in a logical order to ensure overall consistency and avoiduseless repetitions. All sections are introduced by a briefintroduction and attractive illustration. Newly investigatedtopics will be addresses, with the goal of ensuring that thisEncyclopedia remains a reference work for years to come.

Conventional silica sol-gel chemistry is limited for the production of transparent ultralow-density aerogels because (1) gelation is either slow or unachievable, and (2) even when gelation is achieved, the large pore sizes result in loss of transparency for aerogels

This book contains the papers presented at the "First International Sympo st sium on Aerogels (1 ISA)", held in September 1985 at. the University of Wiirzburg, Fed. Rep. of Germany. It was the first meet.ing of this kind, wit.h participants from several European count.ries, the United States of America, Canada, South America, and Africa. The meeting was interdisciplinary, with most of the participants being physicists, chemists or material scientists ei ther from universities or from industrial research institutes. Let me try to shed some light upon the class of substances the symposium was about: Aerogels are extremely porous high-tech materials, consisting ei ther of silica, alumina, zirconia, stannic or tungsten oxide or mixtures of these oxides. Due to their high porosity (up t.o 99%!) and t.heir large inner surface, aerogels serve as especially active catalysts or as catalytic subst.rates, as adsorbents, fillers, reinforcement agents, pigments and gellifying agents. Silica aerogels as translucent or transparent superinsulating fillers in window systems could help to considerably reduce thermal losses in windows and to improve the energy balance in passive solar systems. Aerogels also have fas cinating acoustic properties - the sound velocity can be as low as 100 m/s! The production of aerogels starts with the controlled conversion of a sol into a gel: The growth of clusters or polymer chains from a chemical solution, the cross-linking of these primary entities and the formation of a coherent network - still embedded in a liquid.

Aerogels are the lightest solids known. Up to 1000 times lighter than glass and with a density as low as only four times that of air, they show very high thermal, electrical and acoustic insulation values and hold many entries in Guinness World Records. Originally based on silica, R&D efforts have extended this class of materials to non-silicate inorganic oxides, natural and synthetic organic polymers, carbon, metal and ceramic materials, etc. Composite systems involving polymer-crosslinked aerogels and interpenetrating hybrid networks have been developed and exhibit remarkable mechanical strength and flexibility. Even more exotic aerogels based on clays, chalcogenides, phosphides, quantum dots, and biopolymers such as chitosan are opening new applications for the construction, transportation, energy, defense and healthcare industries. Applications in electronics, chemistry, mechanics, engineering, energy production and storage, sensors, medicine, nanotechnology, military and aerospace, oil and gas recovery, thermal insulation and household uses are being developed with an estimated annual market growth rate of around 70% until 2015. The Aerogels Handbook summarizes state-of-the-art developments and processing of inorganic, organic, and composite aerogels, including the most important methods of synthesis, characterization as well as their typical applications and their possible market impact. Readers will find an exhaustive overview of all aerogel materials known today, their fabrication, upscaling aspects, physical and chemical properties, and most recent advances towards applications and commercial products, some of which are commercially available today. Key Features: •Edited and written by recognized worldwide leaders in the field •Appeals to a broad audience of materials scientists, chemists, and engineers in academic research and industrial R&D •Covers inorganic, organic, and composite aerogels •Describes military, aerospace, building industry, household, environmental, energy, and biomedical applications among others

In recent years, interest in the preparation and characterization of the na-noporous materials has grown due to their distinctive properties and potential applications. Among them, silica aerogel are transparent, highly porous and lightest synthetic solids. Silica aerogels, prepared by sol-gel method followed by supercritical drying, have various extraordinary properties viz. low density ( 20 mg/cm3) and thermal conductivity (0.05 W/mK), low sound velocity ( 100 m/s) and large surface area (> 1500 m2/g). Due to this unique combination of properties, aerogels are considered as a new class solid state porous material having various scientific and technological applications like super insulating transparent fillers in double walled windows, catalytic supports, Cerenkov detectors, filters and containers for capturing of micrometeorites in space. However, economic large-scale industrial production of silica aerogels is hampered by expensive supercritical drying methods. The present book describes the results of detailed studies made on the synthesis and characterization of silica aerogels and related nano-porous materials by various methods and precursors at ambient pressure.

This book reviews the key technologies and characteristics of the modern man-made specialty fibers mainly developed in Japan. Since the production of many low-cost man-made fibers shifted to China and other Asian countries, Japanese companies have focused on production of high-quality, high-performance super fibers as well as highly functionalized fibers so-called ‘Shin-gosen’. ZylonTM and DyneemaTM manufactured by Toyobo, TechnoraTM produced by Teijin, and VectranTM developed by Kuraray are those examples of super fibers. Carbon fibers ToraycaTM from Toray have occupied the most advanced high-performance application area. Various types of polyester fibers having design-shaped cross-sections and special fiber morphologies and those showing specific physico-chemical properties have also been developed to acquire a high-value textile market of the world. This book describes how these high-tech fibers have been developed and what aspects are the most important in each fiber based on its structure-property relationship. Famous specialists both in industry and academia are responsible for the contents, explaining the design concepts and the special technologies for the production of these special fibers. For university teachers and students, this volume is an excellent textbook that elucidates the basic concepts of modern fibers. At the same time, researchers, both in academia and industry, will find a comprehensive overview of recent man-made fibers. This publication, presenting the most easily understandable general survey of specialty man-made fibers to date, is dedicated to the 70th-anniversary of the Society of Fiber Science and Technology, Japan.