Structure-properties relationships in biaxially oriented polypropylene films

A series of biaxially oriented polypropylene films has been extensively investigated with respect to structural characterization and with regard to various end-use properties. The relationships between properties and structural characteristics such as crystallinity content and molecular orientation in crystalline and non-crystalline phases were compared with similar relationships in uniaxially oriented polypropylene films. Notable differences between uni- and biaxially oriented films, in particular with regard to non-linear mechanical behavior (tenacity, impact strength, tear strength) could be explained, at least partly, in terms of structural characteristics (molecular orientation and mobility) related to the non-crystalline phase.