STUDIES OF THE TRANS-QUINACRIDONE NUCLEATION OF POLY-(ETHYLENE-B-PROPYLENE) - DEDICATED TO THE MEMORY OF PROF LAMBLA,MORAND

The poly-(ethylene-b-propylene) was nucleated for a study of the struc ture modifications as well as the improvement of the mechanical proper ties, particularly the impact resistance. The nucleation was accomplis hed by two various red pigments: a linear trans-quinacridone dye (as b eta-phase nucleator) and a dimethyl quinacridone resulting in the form ation of a pure alpha-phase structure. Such procedure allowed the comp arison of both the crystal structure and morphology of the copolymer. For the beta-nucleated copolymer a maximum of the k-value (fraction of beta-phase) was found for a concentration of the nucleating agent of 5 x 10(-4) wt.-%. By means of the WAXS measurement (in the transmissio n and reflection mode) an important structure gradient was detected in the cross-section of the injection moulded samples. This structure gr adient was also observed by optical microscopy, where an agreement bet ween optical observation of the spherulites and the k-value distributi on on the cross-section of the samples was observed. For both nucleati ng agents (linear trans-quinacridone and dimethyl quinacridone) a depe ndence of the mechanical properties of the copolymer (modulus of elast icity and brittleness by impact resistance) on the pigment concentrati on was observed. For the beta-phase nucleated copolymer the maximum of the k-value of the hexagonal crystal structure corresponds to the hig hest ductility by impact test.