CHARACTERIZATION OF ELASTOMER COMPOUNDS BY THERMAL-ANALYSIS

Thermal analysis provides very useful tools for the characterization a nd identification of both, elastomer compound and finished product. Th is investigation focuses on the use of different thermal techniques fo r compositional analysis, characterization of thermal, oxidative stabi lity and glass-transition temperature (T-g) of different components pr esent in the elastomeric systems. Thermogravimetry (TG) is critical fo r identification of composition. TG analysis of three compositions (S- 1, S-2 and S-3) shows S-1 and S-2 are soft-oil extended compounds and S-3 is a hard compound, all comprising ethylene propylene diene rubber (EPDM). Energy dispersive X-ray analysis (EDAX) of the residues from TGA reveals the presence of mineral filler clay in sample (S-3) beside s carbon black. The use of high-resolution TG has been found to give b etter resolution between overlapping weight loss steps leading to bett er quantification of various components compared to conventional TG. T he coefficient of expansion of the rubber compound (from thermo-mechan ical analysis - TMA) above T-g is correlated to the hardness of the sa mples. The use of differential scanning calorimetry (DSC) to determine oxidative stability identifies also the presence of similar antioxida nts, Dynamic mechanical analysis (DMA) is found to be very sensitive f or characterization of glass-transition temperature, visco-elastic pro perties and, in particular, the adhesion between the elastomer compoun d and coating. (C) 1998 Elsevier Science B.V.