Polymers make up an exciting class of biomaterials. Polyethylene is a wonderful
ID: 1056985 • Letter: P
Question
Polymers make up an exciting class of biomaterials. Polyethylene is a wonderful example of a simple ceramic that can be used in multiple applications by modifying its chemical structure. It tends to be bioactive when used by itself as an implant, but it becomes even more bioactive when 10 vol% Calcium Carbonate is added to it. Teflon can be used as a vascular graft material due to its low coefficient of friction. This is achieved because C atoms are replaced by F atoms in its structure. Collagen is the premiere polymer that is produced in our bodies. There are about 15 types of collagen and this polysaccharide is very important in bone matrix formation and tissues and organs. A vacancy is a point defect that occurs when an atom is missing from a lattice position. A perfect metal crystal would exhibit ductile behavior. Amorphous crystals have long range order which can be measured by x-ray diffraction. X-ray crystal structure determination and the iridescent colors in nacre, butterfly wings, and beetle exoskeletons are caused by similar phenomena that involves the transmission of visible light. Metals tend to be harder than polymers, ceramics tend to be stronger than polymers, and metals tend to be harder than ceramics. Diamond is a unique material that exhibits metallic bonding. One of its more unusual features is that although it has a very high electrical conductivity, it is a poor conductor of heat. H bonding is a very important bond type in biological materials such as water and DNA. H bonding is responsible for the anomalous freezing behavior of water in which its density increases when it transforms from liquid to solid. It also plays a role in explaining why Geckos arc able to cling to and run across atomically smooth surfaces. The microstructure of a metal sample that has been cooled from a melt would contain very large crystal grains on the interior and very small crystal grains on the exterior surface. This would be caused by differences in the heating rate w here the exterior cools more slowly than the interior. The (100) plane physically intersects the Y and Z axes and it is perpendicular to the (010) plane and parallel to the (020) plane.Explanation / Answer
a) Plastic is not an example of simple ceramic and rest of the statement a) is true
Orderliness repeated over infinitely great distances is called long-range order, however
b) At great distances the order becomes unclear and gives way to disorder which means that long-range order does not exist in amorphous solids. Ceramics are stronger than metals and polymers as well
Diamond is a bad conductor of electricity but good conductor of heat.
c) There are no facts regarding gecko lizards walking on water and smooth surfaces due to the H-bonding
phenomena. But scientists believe that they generate forces with their feet that keep their bodies
above the surface and keeping them balanced.
d) interior cools more slowly than exterior
e) (0 1 0) plane is a parallel to the (1 0 0) plane