Chain dimension and crystallization temperature affect the II–I transition of isotactic polybutene-1. Issue 32 (25th July 2022)

• Record Type: Journal Article
• Authors: Cui, Xiaopeng; Huo, Jiaxin; Lv, Tongxin; Hu, Cunliang; Li, Hongfei; Liu, Binyuan; Jiang, Shichun
• Is Part Of: CrystEngComm. Volume 24:Issue 32(2022)
• Page Start: 5711
• Page End: 5723
• Publication Date: 2022-07-25
• Subjects: Crystals -- Periodicals; Crystal growth -- Periodicals; Crystallography -- Periodicals; Cristaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Cristallographie -- Périodiques; 548
• DOI: 10.1039/d2ce00765g
• Languages: English
• ISSNs: 1466-8033

Abstract

Abstract : The molecular weight dependence of the II –I phase transformation shows significant differences between isothermally and non-isothermally crystallized iPB-1. Abstract : Isotactic polybutene-1 (iPB-1) usually crystallizes into form II from the melt first and it then spontaneously transforms into form I with outstanding properties. The mechanism of the well-known II –I transition of iPB-1 is still an open question. In the present paper, the II –I transitions of iPB-1 samples with different molecular weights were explored via differential scanning calorimetry (DSC) and X-ray scattering (SAXS) techniques after crystallization at various temperatures. It was found that the initial and final stages of the transition process depend on the molecular weight of iPB-1. A slower II –I transition rate was observed with increasing molecular weight. The total crystallinity increases significantly in the initial stages of the transition, especially for iPB-1 with high molecular weight, after crystallization at higher temperature. The long spacing, lamellar thickness, and amorphous layer thickness of iPB-1 samples with different molecular weights increase with the isothermal crystallization temperature. The SAXS results indicated that the initial crystal transition rate of iPB-1 increases with the amorphous size after isothermal crystallization at various temperatures. The transition process was discussed and a mechanism is proposed, which is helpful for understanding the transition.