Abstract: A series of N,N'-dicyclohexylterephthalamide (DCHT) in different size were prepared via resizing via ultrasonic oscillations. The effect of size on the mechanical properties, the content of β-crystals, and supermolecular structure of isotactic polypropylene (iPP) was studied. It was found that the size of β-nucleating agent could affect the solubility of DCHT in iPP, thus the β-nucleated crystalline morphology changed. Two types of β-form crystalline morphology, namely, "flower"-like agglomerate and β-transcrystalline entity were sequentially observed with increasing content of DCHT. Therefore, it was concluded that β-crystals content might mainly determine the toughness of iPP with the same supermolecular structure. However, β-crystalline morphology should play a dominant role in the toughing of iPP with different supermolecular structure.

Key words: isotactic polypropylene, N, N'-dicyclohexylterephthalamide, β-crystals, crystalline morphology, toughness