Influence of Cooling Rate on the Temperature Rising Elution Fractionation of One Poly(1‐butene‐ co ‐ethylene) Resin and Microstructure of Its Fractions

• Published in: Macromolecular chemistry and physics Vol. 224; no. 21
• Main Authors: Zhang, Zhenkang, Xue, Yanhu, Li, Rui, Liu, Wei, He, Shuang, Ji, Xiangling
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.11.2023
• Subjects: Cooling; Cooling rate; Crystallization; Elution; Ethylene; Fractionation; Gel chromatography; Isotacticity; Microstructure; NMR; NMR spectroscopy; Nuclear magnetic resonance; Resins; Temperature
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.202300180

Abstract TREF (temperature rising elution fractionation) is a method to separate resins based on crystallizability. The influence of TREF cooling rate (V 0 ) on the fractionation process is still unclear. Herein, a poly(1‐butene‐ co ‐ethylene) resin is fractionated by the TREF method at three different cooling rates (1, 2, and 4 °C h −1 ), and then the fractions are analyzed by high‐temperature gel permeation chromatography (HT‐GPC), differential scanning calorimetry (DSC), and 13 C‐nuclear magnetic resonance spectroscopy ( 13 C‐NMR). The cooling rate V 0 affects the crystallization process of the PB‐1 resin, resulting in different fraction contents at the same elution temperature. Furthermore, the cooling rate also affects the chain microstructure of fractions obtained from the same elution temperatures, i.e., the content of 1‐butene and ethylene monomer units, average sequence length and isotacticity. The lower cooling rate is beneficial to the effective separation of the fractions with weak crystallizability. These results have important guidance for optimizing fractionation conditions and obtaining different narrow distribution fractions of poly(1‐butene) (PB‐1) resin.