Influence of the structure of polypropylene fibers on the rate of grafting and the structural changes caused by grafting

An investigation of the relation between the structure of polypropylene fibers and grafting shows that the grafting process takes place in the amorphous phase of the fiber up to 50% grafted polymer content and that the crystals are destroyed only above 75%. This is proved by the diffusion constant of the monomer in the grafted fibers and also by x‐ray diffraction. The studies of grafting rates and diffusion rates of monomers show that the differences in diffusion rate of monomer in fibers of different structures do not affect the rate of chain growth but do affect that of chain termination. The initial rate of grafting is affected by the amount, orientation, and segment mobility of the amorphous part. The chains of the basic polymer are disoriented by grafting, which is indicated by the sudden decrease of birefringence and crystalline orientation. The tensile strength of grafted fiber decreases as the structure changes.