Coagent assisted polypropylene radical functionalization: monomer grafting modulation and molecular weight conservation

The occurrence of significant degradation by β-scission reaction is a severe drawback affecting the classical procedure of polypropylene (PP) functionalization in the melt with maleic anhydride (MAH) or derivatives and free radical initiators. The present work deals with the control of the PP blocks degradation by using a specially designed furan derivative, butyl 3-(2-furyl) propenoate (BFA), as coagent able to control the PP blocks scission during PP functionalization process. More specifically MAH or BFA were used as functionalizing reagents for a propylene/ethylene 77/23 mol% semi-block copolymer (PPC) either separately or as mixture (MAH/BFA) with different molar ratios. The PPC functionalized samples were then characterized by determining the number of grafted groups (functionalization degree FD) and the molecular weight (MW). Finally, the effect of the feed conditions on the process and on functionalized PPC properties are discussed by hypothesizing a reaction mechanism, which takes into account all the occurring parallel reactions.