Orientation studies on hot‐drawn tubular blown films of isotactic polypropene

Orientation studies of hot‐drawn polypropene films were performed using small‐angle light scattering and wide‐angle and small‐angle x‐ray scattering over a wide range of deformation. At low deformation, the classical scheme of affine deformation, as several authors have pointed out, seems to be quite realistic. However, for high deformations, i.e., up to 500%, a new conception of the microfibrillar state is proposed. The microfibrils are formed of fully extended crystals which have a high degree of parallel orientation, but deviations of the units from their ideal position occur. “Wrong” chains are embedded in the lattice, long‐range order is lost, and paracrystallinity appears. A nematic arrangement develops gradually, and we suppose that the “needlelike entities” have some cylindrical symmetry with a crystalline core. The true amorphous component acts as a connection between these zones.