The influence of three nucleating agents from different generations on the crystallization behavior of propylene homopolymer was studied by differential scanning calorimetry (DSC) and atomic force microscopy (AFM). The amount of nucleating agent used varied between 1000 and 2200 ppm. The new generation nucleating agent, Hyperform HPN‑68L, accelerates the crystallization more efficiently than the other nucleating agents tested. It was also possible to verify the effects of agglomeration and negative interaction between calcium stearate and sodium benzoate. Furthermore, AFM images allowed to differentiate the crystals generated by Millad 3988 through the observation of a fibrillar intertwining network structure, with characteristic spacing and length of crystals, justifying its excellent performance to improve polypropylene optical properties
PP nucleated samples showed different characteristics and behavior according to the nucleating agent type and amount used. The old generation and more commom nucleating agent tested (sodium benzoate) showed some limitations regarding agglomeration and interaction with stearates, but it is a good choice to get improvements in PP thermal properties. Hyperform HPN‑68L, an advanced nucleating agent, showed to be more efficient to accelerate crystallization, even with low amounts. Also, it was possible to understand why PP nucleated with Millad 3988 shows very good improvements in optical properties through AFM images, where a network of fibrillar structure was observed instead of defined spherulites. It was also possible to verify that there is an optimum amount of nucleating agent to reach the best performance and properties in nucleated PP and it depends on the type of nucleating agent. In many cases, the use of higher amounts of these additives is unnecessary and, even, as in the case of sodium benzoate, it can affect optical properties.