# HW 32 - 0.7 Using these values the following plot was made...

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Enji Paul Papazisi CEE 300/TAM 324 12/5/12 Assignment 32 In the figure below, the log of Er (t) is plotted against the log of time for poly isobutylene at a variety of temperatures. Make a plot of Er (10) vs. temperature and then estimate Tg based on that plot. Note: t is expressed in seconds. SOLUTION By reading the plot above, the E r (10) values are found by looking at the relaxation modulii values at a time of 10 seconds for each temperature. The values are shown in the table below: Temperature (˚C) Relaxation Modulus (MPa) -80.8 1500 -76.7 1400 -74.1 1300 -70.6 180 -65.4 110 -58.8 50 -49.6 7 -40.1 1 0 0.8 25 0.75 50 0.7

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Unformatted text preview: 0.7 Using these values, the following plot was made to determine the glass transition temperature T g :-100 -80-60-40-20 20 40 60 0.1 1 10 100 1000 10000 Temperature, T (˚C) Relaxatiion Modulus, Er(10) (MPa) FINAL ANSWER: T g = -70˚C DISCUSSION The glass transition temperature is the temperature where the polymer changes from acting as a viscoelastic or viscous material and becomes a brittle elastic material that is significantly weaker. For this material, the glass transition temperature is -70˚C so it is incredibly weak in everyday life. What a shame....
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