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Hypersonic Aircraft
Published in G. Daniel Brewer, Hydrogen Aircraft Technology, 2017
Two examples of structural concepts for the tanks are illustrated in Figure 5–26. At the top of the figure is an integrally stiffened concept made of 2219 aluminum. It is covered with polyimide foam cemented directly to the outside of the tank to serve as cryogenic insulation. The polyimide foam is capable of operating at temperatures ranging from -423 to +400°F. It is wrapped with a vapor barrier to prevent permeation of air into the foam during operation with LH2.
Tailoring specific properties of polymer-based composites by using graphene and its associated compounds
Published in International Journal of Smart and Nano Materials, 2020
Pui-yan Hung, Kin Tak Lau, Qiaoshi Guo, Baohua Jia, Bronwyn Fox
Wang et al. [27] adopted carbon nanotube, as a conductive filler to mix with Polyimide foam to for a composite to isolate EMI transmission. The nanotubes formed a conductive path in the foam network. Dielectric losses would be produced because of induced currents, leading to a drop in the energy electromagnetic waves. However, the article has not specified the type of nanotubes were used as it would make a big difference in terms of their electrical conductivity via the amount of the nanotubes used. Huangfu et al. [28] mixed multiwalled carbon nanotube (MWNTs) and graphene aerogel into Polyaniline (PANI), an excellent conductive polymer to form a composite. Functionalized MWNTs were firstly mixed with graphene to form aerogel and then PANI/MWCNT/Thermally annealed graphene aerogel (TAGA)/epoxy nanocomposite. Increasing the content of MWNTs resulted in enhancing the electrical conductivity of samples. EMI shielding mechanism is same as other metals/alloys with the induced currents flow through. However, the porosity inside the aerogel also caused the internal wave reflection to minimize the EMI interference. Due to the use of graphene, their mechanical properties, such as reduced modulus and hardness increase with increasing the MWNT content. Similar to reduced graphene-based honeycomb structure [29], same mechanism and EMI shielding characteristics were found. Glass transition temperature (Tg) of the nanocomposites was changed with increasing the MXene content. With adding 3.3 wt.% of MXene, Tg was gone up by 10%.
Zinc Oxide–Coated Poly(HIPE) Annular Liners to Advance Laser Indirect Drive Inertial Confinement Fusion
Published in Fusion Science and Technology, 2018
Paul Fitzsimmons, Fred Elsner, Reny Paguio, Abbas Nikroo, Cliff Thomas, Kevin Baker, Haibo Huang, Mike Schoff, David Kaczala, Hannah Reynolds, Sean Felker, Mike Farrell, Brian J. Watson
Several types of foam materials were surveyed for this work including Poly-4-methyl-1-pentene (TPX), divinylbenzene (DVB), polyimide, poly(HIPE), resorcinol formaldehyde (RF), and its pyrolyzed derivative carbonized RF (CRF) based on their previous use in ICF applications.21,22 Each of these foams was a candidate because the foams can be made at densities in the recommended range of 30 to 100 mg/cm3 with pore structures on the order of 1 to 10 μm (Ref. 23). While RF and polyimide both have small pore sizes, RF and polyimide foam machine poorly at low density, whereas CRF machines very well even at densities as low as 50 mg/cm3 (Ref. 24). Thus, the four foams chosen for empirical investigation were poly(HIPE), CRF, DVB, and TPX.
A multi-criteria index to support ecodesign implementation in manufacturing products: benefits and limits in real case studies
Published in International Journal of Sustainable Engineering, 2019
Marta Rossi, Alessandra Papetti, Marco Marconi, Michele Germani
According to the outcomes of previous steps, the company efforts focused on new solutions to increase the efficiency of burners and the oven, satisfying consumers’ expectations. The redesign activities consisted in the study and optimisation of product thermo-fluid-dynamic, ergonomics and usability performance, as well as in the improvement of the control system. For this aim, the company involved heterogeneous resources on the project such as the product manager, the marketing manager and engineers of different technical departments (i.e. mechanical, electrical and automation). In particular, the stoichiometric fuel/air mixture was improved by developing a new typology of forced air burners equipped with a dedicated fan. In this way, the flame distribution resulted in flatter and allowed approaching the pan to the burner and increasing the efficiency. About the oven module, two innovations have been implemented: The installation of a gas burner in the lower part of the oven muffle, which has to operate in combination with the electric components to improve the calorific value and the heat distribution. In this way, it was possible to reduce the pre-heating time, increasing cooking performance and offering to the user a new modality of cooking;The substitution of the actual insulation (i.e. glass wool) with the Solimide® (i.e. polyimide foam certified as a fire-restricting material), which is more sustainable and able to ensure the required insulation performance.