BME/MSE 3700 Exam: Biomaterials Mid Term Exam #1 February 27, 2018 NAME Part I.
ID: 701748 • Letter: B
Question
BME/MSE 3700 Exam: Biomaterials Mid Term Exam #1 February 27, 2018 NAME Part I. True/False. If false, state why. (2 points each) 1)_Condensation polymerization involves the elimination of certain byproducts as part of the synthesis process. 2) _E A polydispersity index (PDID) equal to 1.0 is indicative of a polymer sample with chains with a high degree of variation in length. 3) The yield stress is indicative of the max load a material can sus an prior to failure. 4) The major steps of addition polymerization include initiation with a radical species, elongation/propagation, and termination. An amorphous structure would appear as a series of well defined, narrow peaks on an X. ray diffraction scan. 5) 6)Ceramics generally have a high compression modulus, but low ductility.Explanation / Answer
1. True: Condensation polymerisation the polymers are formed by a condensation reaction where molecules join together losing small molecules as byproducts such as water.
2. False: PDI approaches unity when polymer chains approach uniform chain length.
3. False:
Yield strength - The stress a material can withstand without permanent deformation.
Tensile strength- The maximum amount of tensile stress that it can take before failure, for example breaking.
4. True:
The three steps of this reaction to focus on are
5. False:
Amorphous phase: X-rays will be scattered in many directions leading to a large bump distributed in a wide range (2 Theta) instead of high intensity narrower peaks. ELEMENTS OF X-RAY DIFFRACTION by B. D. CULLITY, pg 101-102
6. True:
The two most common chemical bonds for ceramic materials are covalent and ionic. This is why ceramics generally have the following properties: high hardness, high compressive strength, and chemical inertness. This strong bonding also accounts for the less attractive properties of ceramics, such as low ductility and low tensile strength.
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