Crystallization and Transformation of Polybutene‐1

Abstract

The isothermal crystallization and phase II → I transformation of bulk polybutene‐1 at various temperatures have been characterized by x‐ray diffraction. The crystallization rate can be increased or decreased by the addition of various solids, with sodium salicylate and talc, e.g., increasing the rate by >100% and, unexpectedly, decreasing the rate by >300%, respectively. The nucleating agents have no effect on the transformation rate, which, however, is increased slightly in the presence of water and ethanol and significantly in the presence of liquids that are solvents at elevated temperatures or by temperature cycling. As shown previously, the transformation rate of nontreated polymer is greatest near 25°C, decreasing at higher and lower temperatures and is increased by tension or uniaxial compression.

Keywords:

• Isothermal crystallization
• Sodium salicylate
• Talc
• X‐ray diffraction

Acknowledgments

This research was supported, in part, by Grant ME‐131 from the Granting Agency of the Czech Republic and Grant DMR 0234678 from the Polymer and International Programs sections of the US, National Science Foundation. Appreciation is expressed to Prof. B. Lotz, University of Strasbourg, for numerous helpful comments.

Notes

^aKopp et al. Describe phase I as having a 3₂ helix in the second of their two papers on epitaxial crystallization of PB‐1 from the melt8 and a 3₁ helix in the first paper,7 as well as several others.^[28,29] Being composed of equal numbers of left‐and right‐handed helices, it consists of equal numbers of helices of 3₁ and 3₂ symmetry, both having 3 chemical repeat units in 1 physical repeat.^[30]