Polymer Degradation Laboratory: PMMA Degradation using TGA and Viscometry, Lab Reports of Chemistry

Download Polymer Degradation Laboratory: PMMA Degradation using TGA and Viscometry and more Lab Reports Chemistry in PDF only on Docsity! 1 Ch E 4344/5344 Polymer and Materials Laboratory Spring 2006 TGA/Viscometry Lab 1 Objectives Investigate the degradation of PMMA as a function of time and temperature using viscometry to measure the molecular weight of selected samples; compare the molecular weight obtained from viscometry to that calculated from a model of the degradation kinetics. Equipment TGA 7 in Annex; Viscometry in PE 201 Polymer Poly(methyl methacrylate) Prelaboratory due January 31 Describe the degradation mechanism of PMMA. Find the dependence of the degradation rate on temperature. Find the Mark-Houwink parameters for PMMA with a desired solvent; determine whether the viscometers we have are sufficient for measuring the intrinsic viscosity of PMMA; ensure that the viscometry bath is at temperature. Design temperature scanning and isothermal experiments at various rates and temperatures taking care to determine the time of runs. There are two goals for this lab: 1) to follow the degradation of PMMA in the TGA and 2) to compare the weight loss measured by TGA to the molecular weight. You will need to stop the reaction at different weight losses to do the latter. Some questions to consider in designing your experiments: o How much change in mass do you need in TGA in order to measure the change via viscometry? Should you obtain molecular weight data as a linear or logarithmic function of weight loss? o How long should you allow the instrument to purge before making your run in order to eliminate the effects of adventitious oxygen or moisture? How can you determine this purge time? o What concentrations of solutions should be made to obtain the intrinsic viscosity? Should the concentrations be made at linear or logarithmic dilutions? What is the easiest way to make these concentrations? o How much material do you need to make your viscometry solutions? Will you have enough material from your TGA experiments to do this or will it be easier to perform degradation in an oven? o To correlate weight loss to molecular weight, should you do this for all degradation temperatures/scanning rates, or is it sufficient to perform this correlation for one degradation temperature?