Exam 1 Keypdf - POLYMER PHYSICS Spring 2003 EMA 6165 EXAM I...

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POLYMER PHYSICS - Spring 2003 STUDENT UFID#:_________________________ EMA 6165 – EXAM I (use the NEW UF ID No.) INSTRUCTIONS: Read the entire exam carefully. Answer every question to the best of your ability, based upon the available information. State all assumptions you use in answers. HONOR CODE : We, the members of the University of Florida community, pledge to hold ourselves and our peers to the highest standards of honesty and integrity. Signature:___________________________________________________________ SECTION I: Polymer Structures/Properties. 1. Draw the repeat units for the following polymers. 2. State the relative Tg and/or Tm for each polymer (24pts) Polymer Structural Repeat Unit (2pt) Tg (1pt) Tm (1pt) 1. poly(styrene) Assuming Amorphous 100 C N/A 2.poly(1,4- butadiene) Assuming Cis -100 C 0 C 3. poly(isoprene) Assuming Trans -70 C 68 C 4. poly(bis phenol A carbonate) Assuming Amorphous 150 C N/A 5. poly(ethylene) Assuming HDPE -120 C 135 C 6. poly(dimethyl siloxane) -125 C -40 C
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POLYMER PHYSICS - Spring 2003 EMA 6165 - EXAM I Concepts. Answer the following statements with TRUE or FALSE . If the statement is false, state the reason(s). If you believe a statement can be made TRUE by a simple qualifier, then state it clearly. (12 pts) 7. The Young’s modulus in tension is independent of strain rate for a thermoplastic tested below the Tg. . False, replace with dependent 8. The freely rotating, freely jointed model underestimates the radius of gyration of poly(1,2-butadiene) by a factor of 3 compared to the freely rotating model (Assume theta conditions). False, replace with the Characteristic Ratio 9. The w- average molar mass of a polymer is most accurately measured by light scattering. True 10. The tan delta of a polymer increases at the glass transition with increasing frequency of the input strain amplitude. False, replace with decreases 11. The rotational isomeric state value increases with the concentration of cross link junctions in a sample of poly(1,2-butadiene) cross linked by 60 Co radiation in an argon atmosphere (Assume theta conditions for the measurement of the rotational isomeric states). False, replace with decreases 12. The force divided by the root mean square end-to-end distance is a measure of the stress per single chain. False, omit “root” 2
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POLYMER PHYSICS - Spring 2003 EMA 6165 - EXAM I II. Graphical Relationships: You must provide the appropriate equations for answering each question. You must label axes appropriately and provide appropriate units and orders of magnitude.
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This note was uploaded on 07/20/2011 for the course EMA 6165 taught by Professor Brennan during the Spring '08 term at University of Florida.

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Exam 1 Keypdf - POLYMER PHYSICS Spring 2003 EMA 6165 EXAM I...

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