Dicumyl peroxide as initiator

Table II shows molecular weight distributions of products from monomer mixtures A and B using 3% dicumyl peroxide as initiator. The molecular weight distributions of the products from the six polymerizations are 3 or less. When, however, the percent of dicumyl peroxide was decreased in the reaction mixture, considerably wider molecular weight distributions resulted (Table III). With less initiator, the chains grow longer and terminate more often by chain transfer.

After preliminary studies conducted on isotactic polypropylene and maleic anhydride in the presence of dicumyl peroxide as initiator, we concluded, in agreement with several others, the existence of a maximum grafting level, or ceiling, whatever was the initial concentration of maleic anhydride and peroxide in the reaction media. By using a statistical design method for experimental runs, it was put into evidence that results needed to be carefully evaluated in order to find the true evolution of the process. 

---