Kevlar in Space Suits - Krypton MCV @introtomaterialsscience--g4

Uploaded May 2014 | Updated September 2026, 55 minutes ago

Kevlar: Keeping Astronauts Safe in Space
Erica, Evan, Jim, Rachel

Protecting humans while in space is an important technological challenge. As scientists try to explore the solar system and observe the Milky Way, they need to be able to survive the harsh conditions of space. Space suits provide the essential oxygen, pressurized atmosphere, and protection from extreme temperatures and micrometeoroids for humans as they move outside of the International Space Station. One crucial material used in making these space suits is Kevlar (Poly-paraphenylene terephthalamide). Woven Kevlar helps solve the challenge of putting humans in space because it is strong, yet lightweight, and allows for some motion of the body unlike a hard, solid metal. Kevlar's strength is attributed to a combination of inter-chain hydrogen bonds and stacking interactions between adjacent bonds. The process of production of Kevlar also gives it strength. It is drawn into fibers and then sewn in a crosshatched pattern into a fabric. Kevlar can ideally hold its strength down to -196°C, which is important for space travel, as it can get extremely cold outside of the earth's protective atmosphere. If exposed to extreme heat, Kevlar will not melt like other plastics, and will only degrade after reaching 450 degrees C. There are also other insulators in space suits that protect astronauts from the extreme temperatures of space. Because of the nature of Kevlar it has a versatile array of uses such as bulletproof vests, paneling on air force jets, helmets, and cut-resistant gloves. Kevlar has qualities that make it very protective from punctures, thus enabling engineers and designers to utilize these qualities for the manufacturing and future development of safer and more lightweight space suits.

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$Contact Lenses - Silicone Hydrogel By Michael Shiu, Colin Kim, and Kevin Allman Silicone hydrogels are used for the manufacture of soft contact lenses. In today’s society, which is a highly visual world full of electronic screens, hyperopia (farsightedness) is a growing problem among individuals, especially as they get older. Hyperopia is caused by parallel light rays not bending sufficiently to focus by the time they reach the retina due to weaknesses in the relaxed lens system. Thus, there is a need to improve the technology of contact lenses. A physical property of silicone hydrogels is the ability to refract light; so convex silicone hydrogel lenses can be used to increase the refractive power of the eye to correct the effects of farsightedness. It is, therefore, important that the material used to manufacture contact lenses is able to do this without distortion and maintain clarity. Silicone hydrogels have sufficient elasticity that allows them to conform to slightly different eye surface shapes depending on the person wearing the lenses, maximizing comfort and effectiveness. A key issue with contact lense materials is their oxygen permeability. Oxygen permeability is important because it allows the cornea to receive adequate amounts of oxygen to prevent hypoxia of the eye through the diffusion of oxygen gas through the actual contact lens. When passed through silicone, the oxygen permeability increases. On the other side, wettability, which is measured by the angle of the contact lens, is important because a complete wetting will permit a thick coverage of the tear film, a smooth recovery of the tear layer after the eyes are closed, and adequate visual acuity. This leads to a longer duration of wearing the lenses. This is a limitation to silicone hydrogel lenses, for its hydrophobic nature produces a poorly wettable surface. However, through the complementary use of wetting agents such as eye drops, the limitation becomes negligible. Another limitation is the lipid depositions during wear, which leads to blurry vision and contact lenses. Compared to conventional lenses, the presence of silicone leads to a much greater lipid deposition. Overall, silicone hydrogel contact lenses are a breakthrough technology, increasing oxygen permeability while maintaining wettability to improve comfort. Because silicone hydrogel lenses are fairly new to the market, the costs of these lenses are higher on average, but the costs are expected to decline over time with increased availability. More research needs to be conducted to improve the issue of wettability. Currently, there are products that help re-hydrate the lens to reduce issues with discomfort and lipid deposits, but changes to the structure and composition of silicone hydrogels could eliminate the need for such extraneous products that only add to the total cost of using this kind of contact lens. Moreover, the 3 features (Process/Structure/Properties) of the MSE triangle will be discussed throughout the video. Images/Videos Used 1) https://www.youtube.com/watch?v=Av1ZiN9P01s 2) http://opticalvisionresources.com/wp-content/uploads/2013/11/WB-1930contact_lense.jpg 3) http://www.topconsumerreviews.com/contact-lenses/new-images/header-contact-lenses.jpg 4) http://blog.eyedo.in/wp-content/uploads/2015/09/sillicon.jpg 5) https://www.youtube.com/watch?v=JoxuBcg7S1o 6) https://upload.wikimedia.org/wikipedia/commons/thumb/d/d2/Vinylpyrrolidon.svg/100px-Vinylpyrrolidon.svg.png 7) http://www.sigmaaldrich.com/content/dam/sigma-aldrich/structure4/061/mfcd00002651.eps/_jcr_content/renditions/mfcd00002651-medium.png 8) https://upload.wikimedia.org/wikipedia/commons/thumb/7/7e/Polyhydroxyethylmethacrylate_structural.svg/160px-Polyhydroxyethylmethacrylate_structural.svg.png https://en.wikipedia.org/wiki/Silicone_rubber#/media/File:Pdms.png 9) https://www.youtube.com/watch?v=Kas5v8isarw 10) https://www.google.com/search?q=wettability&espv=2&source=lnms&tbm=isch&sa=X&ved=0ahUKEwinstny1aTTAhWEJCYKHQ11CQwQ_AUIBygC&biw=1163&bih=537#imgrc=H_P6AgnahnNrWM: 11) http://www.tekra.com/resources/tek-tip-white-paper/tek-tip-hydrophilic-vs-hydrophobic-coatings 12) http://www.clspectrum.com/issues/2002/march-2002/silicone-hydrogel-material-and-surface-properties https://www.google.com/search?q=infected+eye+from+contact+lenses&rlz=1C1CHBF_enUS710US711&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjQz8CdhqPTAhUF6yYKHVh7Df0Q_AUICCgB&biw=1280&bih=591#imgrc=9YM4T87Yb_ht7M 13) http://www.allaboutvision.com/contacts/contact_lenses.htm#materials 14) http://www.clspectrum.com/archive/2002/march/26b.jpg Research Sources https://docs.google.com/document/d/1GDPFO3BJQQb0sly3vr1snuPG-Af2ZeQnvTpqJ3yBpoE/edit?usp=sharing$

$Titanium Implants- Nickel MCV Materials Challenge: Implants I am Titanium For centuries, humans have been searching for materials to replace damaged or failed human tissue. These tissue replacements, or implants, have included everything from bits of shell hammered into the jaw to replace missing teeth to the metal hip and knee replacements we see today. There are many unique challenges in selecting materials for implants, as in addition to having properties similar to the failed biological component the implant must repair or replace, any material used must not be toxic to the human body. Titanium is a commonly used material in implants because it is strong, durable, and bonds with bone. It is not perfect, however, the high Youngs modulus, or stiffness, of titanium can result in stress shielding where the implant bears more of the bodys load than the surrounding bone, causing the bone tissue to weaken and fracture. Our video will provide an introduction to implants by defining the term, giving a brief history of the development of implants, and giving some examples of the types of implants used today. We will then discuss the specific properties required of implants, including strength, durability and biocompatibility. We will then discuss titanium implants specifically the properties of titanium, what makes it work well for implants, as well as some of the challenges associated with the use of titanium and its alloys. We will discuss stress shielding in more detail, and demonstrate cold working a process by which the yield strength of metals can be increased without affecting the Youngs modulus. References: 1. Arsenjev, A. P.; Arsenjev, P. A.; Evdokimov, A. A.; Makaricheva, E. U.; Sheinin, M. J., The processing of surgical implants from pure titanium, Biomedical Engineering Conference, 1996., Proceedings of the 1996 Fifteenth Southern , vol., no., pp.384,385, 29-31 Mar 1996 http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=493256&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D493256 2. C.N. Elias, J.H.C. Lima, R. Valiev, and M.A. Meyers. Biomedical Uses of Titanium and its Alloys. JOM, March 2008. Pgs 46-49. http://www.meyersgroup.ucsd.edu/papers/journals/meyers%20316.pdf 3. M. Niinomi and M. Nakai, Titanium-Based Biomaterials for Preventing Stress Shielding between Implant Devices and Bone, International Journal of Biomaterials, vol. 2011, Article ID 836587, 10 pages, 2011. http://www.hindawi.com/journals/ijbm/2011/836587/ 4. Neailey, K., and Pond, R.C. (1982). Metal implants. Materials & Design, Volume 3, Issue 3, Pages 470-478. http://www.sciencedirect.com/science/article/pii/0261306982901133. 5. Springer Science+Business Media. (2011, July 26). Heavy metal: Titanium implant safety under scrutiny. ScienceDaily. Retrieved May 5, 2014 from www.sciencedaily.com/releases/2011/07/110725101257.htm 6. Slides from a Materials Science/Biomaterials Course; details processes, properties and uses of metallic biomaterials: http://www.bioen.utah.edu/faculty/pat/Courses/biomaterials2006/Metals%20and%20Applications%20in%20Orthopedics.pdf 7. How Its Made (YouTube clip): Titanium Dental Implants https://www.youtube.com/watch?v=S4j_GOYFoG8 All unoriginal images were unlicensed and accessed through Wikipedia. Titanium by David Guetta ft. Sia$

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