Effect of an additive TAB-1 on crystallization behaviors and tensile properties of iPB-1

Abstract

The excellent high-temperature performances of isotactic polybutene-1 (iPB-1) in form I are demanded by many thermoplastic products like hot water pipes. However, as the iPB-1 melt is a strong liquid with chain conformations difficult to adjust, melt processing and molding of iPB-1 are difficult due to the resulting high viscosity and slow melt crystallization kinetics as well as the following slow II–I transition which seriously hindered its industrial applications. The approaches to improve the processing and molding performances with balanced mechanical properties of iPB-1 are appealing. Following our previous report on an additive TAB-1 that can accelerate the II–I transition, we further focused on the crystallization behaviors and the final tensile properties of iPB-1 after TAB-1 incorporation. The results showed that the T_c,peak, T_m and crystallinity increased and the form II spherulite growth was enhanced but the spherulite nucleation density remained fixed. The crystal lamellar thickness increased and no negative effects on the tensile properties of the final form I iPB-1 were observed. TAB-1 incorporation weakens the strength of the iPB-1 melt liquid and favors crystal reorganization during tensile stretching with slightly increased tensile strength and elongation at break. The almost fixed strain hardening modulus indicates good resistance to the slow crack growth of iPB-1. The results are of industrial importance for iPB-1 melt processing and molding and thus its applications.