Fast-Track Crystallization of PB-1 with Sorbitol-Based Nucleating Agent

The work is focused on crystallization and phase transition of polybut-1-ene (PB-1) homopolymer and random copolymer in the presence of commonly used nucleating agent (NA) 1,3:2,4-bis-(3,4-dimethylbenzylidene) sorbitol, primarily designed for polypropylene. The crystallization and subsequent phase transition from kinetically preferred tetragonal form II into thermodynamically stable trigonal form I in defined times of aging at room temperature is studied. It was found that NA accelerates phase transition, particularly in homopolymer. In the copolymer, moreover, the addition of NA dramatically increases the crystallization temperature and narrows the crystallization peak as well as the melting peak, which corresponds to the formation of a more uniform structure. At the same time, the addition of NA increases the haze significantly, confirming the formation of a two-form structure. However, NA was found to be soluble in a low concentration (0.2 wt %) in PB-1 melt at a sufficiently high temperature of melting. The solubility then affects the crystallization behavior. Finally, it can be confirmed that the addition of commercial sorbitol-based NA has a significant effect on the crystallization and phase transition of both the PB-1 homopolymer and the copolymer.