Structure and properties of injection moldings of beta-crystal nucleator-added PP - Part 6, Addition of beta-crystal nucleator to particulate-filled polypropylenes

Aiming at a synergism of improvements of impact strength of polypropylene b y the addition of beta-crystal nucleator and of its rigidity by the filling of particulate, the addition of the nucleator to particulate-filled polypr opylenes has been studied a to 3000 ppm of gamma-quinacridone (GQ) which is a beta-crystal nucleator was added to homo isotactic polypropylenes (PP) f illed with 0 to 30 wt-% of tale (TC) which shows an alpha-crystal nucleatin g effect, of mica (MC), or of glass flake (GF), last two of which show beta -crystal nucleating effects. Flexural and Izod impact test specimens were i njection-molded from the PPs under constant molding conditions and the stru cture and properties have been investigated. The beta-crystal content is re duced by the filling of particulates. The degree of the reduction is in the order of TC > MC > GF, which agrees with that of the crystallization tempe r-attire. The flexural modulus decreases slightly with increasing Ge conten t and increases with increases in particulate contents. The increase is in the order of MC > TC > GF, which agrees with that of the aspect ratio. The enhancing effect of the Izod impact strength by the addition of GQ decrease s with increasing particulate contents and diminishes at contents above 10w t-%. Particulates deteriorate the enhanced impact strength of beta-PP. Thus the expected synergism could not be obtained enough.