Polypropylene is a semi-crystalline polymer as many other polymers are, i.e., it comprises amorphous and crystalline regions. When polypropylene crystallizes from the melt, the onset of the phase transformation is the formation of small nuclei.

Once this primary nucleation has occured, the crystal can grow and form spherical macrostructures called spherulites. The use of nucleating agents leads to higher nucleus density allowing for the formation of a larger number of spherulites during the cooling of the melt, whereas in non-nucleated Polyproyplene the spherulites are typically less numerous and are smaller.

Effect of nucleating agents
The change of the number and size of spherulites by nucleating agents affects the properties and the processing of polypropylene and expands its application window significantly.

Without Nucleating Agents                       With Ciba® IRGASTAB®

Improved physical and mechanical properties
Nucleating agents increase several physical and mechanical properties of polypropylene such as stiffness, impact properties, hardness, heat distortion temperature, etc. The improvement of mechanical properties generally enables downgauging, thinwalling and weight reduction of the finished parts.

Reduced cycle-time and increased output
The overall rate of crystallization of polypropylene increases when using nucleators. A higher crystallization speed ensures a faster solidification of the molten polymer  upon cooling. This leads to a reduction of cycle-time in molding processes and generally to increased output as well.

Improved optical properties
The smaller size of spherulites improves the transparency or haze as well as the clarity of polypropylene articles.

Application

Automotive Exterior
Automotive Interior

Product Nucleating Agents

IRGASTAB® NA 11