THERMAL-DEGRADATION OF MODEL LINEAR AND STAR-SHAPED POLYISOPRENE MOLECULES

The thermal degradation behavior, in the absence of air, of model star -shaped and linear polyisoprenes with silyl alkyl groups, prepared usi ng anionic polymerization techniques and chlorosilanes as linking agen ts, has been investigated and compared with that of model linear polyi soprenes. Thermal stabilities were examined by thermogravimetry and di fferential scanning calorimetry, while analysis of degradation product s and of polymer residues obtained after different thermal treatments was performed by gas chromatography-mass spectrometry, H-1-NMR, FTIR a nd size exclusion chromatography. The temperature at which polymer dec omposition takes place, the shape of the weight loss curves and the na ture of the compounds formed during the degradation seems not to be in fluenced by the structural differences or the presence of silyl alkyl groups in the polyisoprene molecules. However, the star-shaped polymer s show a higher tendency for coupling and cross-linking during degrada tion.