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ADDENDUM

1 The rubber band should already be mounted in the probe. Please do not remove or touch it. If there is a problem, notify Dr. Williams, if she is available.

2. On the TMA module, press the SCROLL key several times until the SIZE read-out is activated. Press MEASURE LENGTH and wait until the reading appears (top window changes from MEASURE to TEMP). Repeat the measurement several times, and use the average for the I, value of the band.

3. If the furnace is in the up position, make sure that it is centered over the probe. Press the FURNACE key to lower the furnace into position.

4. On the computer press the F12 key to enter the INSTRUMENT CONTROL section. Use the right cursor to highlight the TMA window at the top of the screen.

5. Press F4 to enter the EXPERIMENTAL PARAMETERS sub-menu and then F2 to access the METHOD EDITOR. The methods have already been written and stored as numbers 1-5. Use the F5 key to select the one to be run and ESCAPE back to the EXP PARAMS screen.

6. Press Fl to access the SAMPLE INFORMATION screen. Complete the following

sections: Sample, Operator, Comment, Data Filename. The module will automatically enter the Size into the data file (should be close to the values obtained in step 2). The Run Number is also automatically updated by the computer. The data will be saved on the C: drive.

7. With the exception of the isothermal run at 500C, the coolant reservoir on the top of the furnace must be filled. Obtain several chunks of dry ice, wrap them in a cloth and pound them to small pieces. Pack the reservoir as uniformly as possible before the run starts, and try not to add more during a run. (The vibration may ruin the data.)

8. Make sure that the nitrogen purge gas flow reads about 100-1 20 (black ball) on the far right meter.

9. Press the START key on the TMA module, and, as mentioned above, try not to disturb the instrument until the run has finished. At the end of the run the furnace will be automatically raised.

It is advised that the General Analysis software be used, because it is applicable to all three modules, and it has the capability to send data tables to the printer (sorry, no ASCII output to feed directly to Lotus or Quattro). The following new scheme should provide the necessary data. In all cases, use units of newtons for force, % for dimensional change, ^oC for temperature, and minutes for time.

Isothermal Data Sets: The program does not make plots of force vs elongation or vice-versa, but each can be obtained as plots versus time. On a single sheet plot time on the x-axis and both dimensional change (Signal A) and force (Signal B) on the y-axis. To obtain a hard-copy, press F4 followed by Fl for the plotter. Then press F6, followed by F2 to obtain a data table. For each isothermal run, prepare one table containing data obtained over the entire time span of the force ramp (omit the initial equilibration part) at 0.5 minute intervals. Send it to the printer (Data Transfer Switch next to the printer in the B position). Use these values to prepare the plots described in the handout, Data Analysis step 7.

For each isothermal data set determine the time range over which the % elongation changes from about 40 to 50 % (relative elongation of 1.4 to 1.5). This range is chosen to 'bracket' the elongation set in the isostrain measurements (as well as the elongation range in the isostrain runs). Prepare another table of data for this range only at 0.1 minute intervals. Use these results to prepare a plot of stress versus relative elongation. Over this limited elongation range the plot should be linear, and the slope is equal to Young's modulus. (This calculation replaces the one decribed in the handout, Data Analysis step 2, except that the force must still be divided by the cross-sectional area to convert to stress.). The LLS equations can also be used to calculate the information specified in the handout, Data Analysis step 3.

Isostress Data Sets: Referring to the handout, Data Analysis step 4, a plot of the relative elongation versus temperature is needed. However, both descending and ascending temperature ramps were performed, and it is easier to obtain the tabulated data with time plotted on the x-axis.

On a single sheet plot time on the x-axis and both dimensional change and temperature on the y-axis. Obtain a hard-copy and a data table at 2 minute intervals. Use these results to prepare a plot of relative elongation versus temperature. Then proceed as described in the handout, Data Analysis step 4.

Isostrain Data: On a single sheet plot both force and temperature versus time. Obtain a hard-copy and a table at 2 minute intervals. Then proceed as described in the handout, Data Analysis step 5.

Summary: The modifications to the steps in the Data Analysis are summarized below. Also be sure to calculate the 95% confidence intervals of all results, as specified in the handout.

1. Unchanged

2&3. See Isothermal section above.

4. See Isostress section above.

5. See Isostrain section above.

6. Unchanged

7. See Isothermal section above. Otherwise, unchanged.

8. Unchanged

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This document originated from Professor Kathryn R. Williams