The Effect of Initial Molar Mass on Chemiluminescence Runs

THE EFFECT OF INITIAL MOLAR MASS ON CHEMILUMINESCENCE RUNS 

The effect of molar mass and stereoregularity on the thermo-oxidation of polymers and on the chemiluminescence-time patterns has been investigated only rarely [44-46]. 

There are still some non-explained observations. For example, syndiotactic PP was reported [45,46] as being more stable than isotactic polymer. At 140°C, the maximum chemiluminescence intensity was achieved after 2,835 min for syndiotactic PP, while isotactic polymer attained the maximum after only 45 min. Atactic PP was reported to be more stable than the isotactic polymer [46]. An explanation has been offered that the structure of isotactic PP is much more favourable for autooxidation, which proceeds easier via a back-biting mechanism where peroxyl radicals abstract adjacent tertiary hydrogens on the same polymer chain. 

However Iring et al. [47] found that the induction period for oxidation of solid isotactic PP is longer than that for atactic polymer. Their result is in accordance with the high crystallinity of isotactic PP and with the resistance of its crystalline zones to oxidation. 

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The Effect of Initial Molar Mass on Chemiluminescence Runs 478... 

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