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Abstract
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An investigation on the structural and morphological variations of oriented polypropylene (PP) films processed by
two different methods, including biaxial oriented cast film processing (film tentering) and film blowing process
(tubular film extrusion) was conducted. Thermal properties obtained by differential scanning calorimetry (DSC)
showed no significant difference in melting behavior of machine direction oriented (MDO) film and the unoriented
cast film, however, after transverse drawing (TDO) a small second melting peak appeared on the left-hand side of
the DCS thermogram which was ascribed to presence of kebab lamellae, and the appeared sharp peak was
attributed to shish structures in the biaxially oriented PP (BOPP) film. On the other hand, a crystalline structure
characterized by wide X-ray diffraction (WXRD) manifested an intensified peak pertinent to the formation of another
crystalline structure, i.e. ?-modification throughout the blown PP film, contrary to the cast films in which solely ?
phase existed. The topography of the surface taken by atomic force microscopy (AFM) represented an extensive
fibrillar texture in the BOPP film which was in accordance with their DSC results.
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