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Unformatted text preview: POLYMER PHYSICS - Spring 2001 NAME:___________________________ EMA 6165 - EXAM I STUDENT #:______________________ 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) a. poly(butadiene) b.poly(methyl methacrylate) c. poly(isoprene) d. poly(bis phenol A carbonate) e. poly(ethylene) f. poly(dimethyl siloxane) POLYMER PHYSICS - Spring 2001 EMA 6165 - EXAM I 4. 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) a. The shear modulus is indirectly proportional to the mole fraction of active chain segments of an ideal elastomer below the Tg. b. The freely rotating, freely jointed model underestimates the radius of gyration of polyethylene by a factor of 3 compared to the freely rotating model (Assume theta conditions). c. The n- average molar mass of a polymer is most accurately measured by light scattering....
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