Morphological characterization of branched PP under stretching

An effective approach to achieve high-melt strength polymer is to add long chain branches onto backbone species using gamma radiation. Grafting and branching result from macroradicals combinations during the irradiation process. Polypropylene films were prepared starting with irradiation process of the pellets with a ⁶⁰Co source at doses of 5, 12.5, and 20 kGy under acetylene to improve melt strength and drawability. After irradiation, polypropylene films were obtained by compression molding, at 190 °C and pressure of 80 bar, and dive into a water tank at 23 °C, which generally favors the formation of an amorphous phase. The thin films were stretched at 170 °C using a universal testing machine. Film surface morphology and the thermal properties, were analyzed, using atomic force microscopy, scanning electron microscopy and differential scanning calorimetry. We had a different molecular structure that requested the study of their micro and nanostructure. The results showed some evidence of fibrillar structures containing crystallites and gel formation. Fibrils oriented along the stretching direction were observed.