Development of Self-Assembling Nucleators for Highly Transparent Semi-Crystalline Polypropylene

In 1,3:2,4-bis-O-(p-methylbenzylidene)-d-sorbitol (PDTS)/molten i-PP systems, the self-assembling ramified fibrils of PDTS are formed at Tfg,c higher than Tc during the cooling process. They function as the nucleators for the nucleation of molten i-PP. The ramified fibrils have the following characteristics: i) hexagonal crystal with the lattice cell a = b = 30.2, c = 4.4 Å, and γ = 120°, ii) mass fractal structure with large specific surface area, and iii) random orientation. Thus the following properties are induced for the i-PP: i) excellent transparency so that the lamellae build a sheaf-like crystalline superstructure with a small apex angle, ii) iso-directional and improved mechanical properties, and iii) shortened molding time.