2.2. Specimen preparation
PP samples were premixed with a 0.1]2 wt.% nucleating agent by means of a dual bolt extruder. The notched charpy impact specimens were made first by injection, molding and milling into the predetermined geometry 10=4=60 mm., then a 458 V-notch, 3 mm in depth, was machined at the center of each specimen.The radius of each separate notch root was 0.1, 0.25,0.5 and 1.5 mm, respectively.