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V magistrski nalogi smo proučevali vpliv α, β in kombinacije α/β nukleatorjev na reološke, termične in mehanske lastnosti polipropilen homopolimera (PPH) in polipropilen kopolimera (PPC). Reološke lastnosti smo opazovali z meritvami indeksa tečenja (MFI - melt flow index), termične lastnosti smo proučevali z diferenčno dinamično kalorimetrijo (DSC - differential scanning calorimetry), s trgalnim preizkusom smo proučevali mehanske lastnosti. Nukleatorji so imeli večji vpliv na reološke lastnosti v primeru modifikacije PPC, na PPH je imel vpliv samo dodatek α/β - nukleatorja. Z dodatkom nukleatorjev k PPH in PPC smo opazili povišanje temperature kristalizacije. Prav tako smo v primeru modifikacije PPC povišali stopnjo kristaliničnosti. Pri PPH smo z dodatkom β - nukleatorja opazili padec kristaliničnosti. Temperaturni pik taljenja se je, zaradi promocije β - kristalitov, v primeru β - nukleatorja znižal, ostali vzorci so imeli pik v področju α - kristalitov. Vzorec PPHα1 je povišal čas oksidativne razgradnje (OIT - oxidative induction time), vsi ostali opazovani vzorci so ga znižali. Rezultati kažejo na povišanje togosti modificiranega PPH (razen v primeru β - nukleatorja) ter modificiranega PPC in zmanjšanje natezne trdnosti na meji plastičnosti (razen v primeru β - nukleatorja) za oba modificirana PP. Opazili smo povezanost trdote s togostjo β - nukleator je v PPH znižal togost in povišal trdoto. Pri modifikaciji PPC so vsi nukleatorji povišali trdoto. This master thesis studied the effect of α, β, and the combination of α/β - nucleators on rheological, thermal and mechanical properties of polypropylene homopolymer (PPH) and polypropylene copolymer (PPC). Rheological properties were monitored by measuring flow index (MFI - melt flow index), the thermal properties were studied by differential scanning calorimetry (DSC - Differential Scanning Calorimetry), and with a tear-off test, the mechanical properties were studied. Nucleators had a greater influence on the rheological properties in the event of PPC modification. PPH was influenced only when the α/β – nucleator were added. With the addition of nucleators to the PPH and PPC, an increase in the temperature of crystallization was noticed. In the case of PPC modification we have also increased the degree of crystallinity. When we added the β - nucleator to the PPH a drop in crystallinity was noticed. Due to the promotion of β - crystal in the case of β – nucleator the temperature of melting peak was reduced, whereas the other samples had a peak in their area of the α - crystal. PPHα1 sample increased the OIT - oxidative induction time, while all the other observed patterns reduced it. The results show an increase in the stiffness of modified PPH (except in the case of β - nucleator) and modified PPC along with the reduction of the tensile yield strength (except in the case of β - nucleator) for both modified PP. A connection between hardness and stiffness was noticed β - nucleator reduced stiffness and increased hardness when added to the PPH. When modifying the PPC, all nucleators increased the hardness.