Polypropylene (PP) derivatives, prepared with different α-olefin comonomers of hexane and hexenol, were investigated using the positron annihilation lifetime technique. The free-volume hole sizes for the present polymers were quantified from the long-lived ortho-positronium (o-Ps) lifetimes. In contrast to the case of nonpolar, introduction of the polar hexenol into PP reduced the o-Ps lifetimes and the hole sizes derived from them. This indicates that the interchain interaction due to the hydrogen bonds in the amorphous region is much stronger than the enhancement of the segmental motion due to the butyl long branch. A comparison of the o-Ps lifetimes with the corresponding tensile strength suggested significant contribution of the subnanostructure in the amorphous region to the mechanical property.
Decoupling bulk and surface recombination properties in silicon by depth-dependent carrier lifetime measurements