Using Chemistry in Compositional Analysis by Thermogravimetry

Abstract

Many of the compositional analysis applications involving thermogravimetry have focused on the determination of concentrations of one or two additives to a polymeric matrix. Paramount to the utility of such a thermogravimetric approach for filled polymers is that the matrix pyrolyzes repeatably, if not completely. Equally important is the understanding of the components constituting the high temperature residue (ash) and how they are derived. Two examples will be addressed in which controlling or understanding the chemistry of the experiment highlights the significance of the above-mentioned factors in achieving useful compositional analyses. In the first example, an ammoniated atmosphere is employed to achieve repeatable pyrolysis of silicone rubber to measure the carbon black filler content. The second example emphasizes the understanding of decomposition chemistry to distinguish two inorganic fillers retained as ash. In this example the evolution of CO2 from CaCO3 is used to identify the calcium oxide portion of the ash in a polystyrene + carbon black + silicone oil + calcium carbonate + titanium dioxide system.

Application of Chemical and Thermal Analysis Methods for Studying Cellulose Ester Plastics

“…While it is certainly possible to measure the concentration of additives in CA polymers using Py-GC/MS, developing suitable test protocols for the possible range of additives used in CA would be difficult. In comparison, TG affords a simple means of measuring the total content of volatile additives based on the magnitude of the initial weight loss step. , As Figure shows, no well-defined weight loss step is evident below 260 °C for the CA standard from SPP, whereas for the other CA samples the weight losses range from 20% to 30% (Table ). In assessing the aging behavior of plasticized CA, TG can be an excellent tool for tracking changes in volatile plasticizer content.…”