Strain-induced changes of the X-ray diffraction patterns of cross-linked Poly(dimethylsiloxane): The texture hypothesis. (28th April 2022)

• Record Type: Journal Article
• Authors: Shi, Xiang; Albouy, Pierre-Antoine; Launois, Pascale
• Is Part Of: Polymer. Volume 247(2022)
• Publication Date: 2022-04-28
• Subjects: Crystal structure -- Orientation -- X-ray diffraction; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2022.124760
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Poly(dimethylsiloxane) is a widely used silicone polymer that undergoes partial crystallization both as free oil and rubber when sufficiently cooled. However, a description of its crystalline structure surprisingly remains a totally open question. In particular X-ray diffraction fiber patterns of stretched silicone rubbers display impressive changes with strain and a recently proposed explanation involves a rich polymorphism. The present study develops the different idea that the X-ray pattern evolution merely reflects changes in the crystalline texture: a single crystalline phase is present with a structure virtually unaffected by strain while the axis of preferential orientation for the crystallites progressively changes. This enables a quantitative description of the X-ray fiber patterns, but the remaining fundamental structural issues are underlined. Graphical abstract: Image 1 Highlights: The structure of the crystalline phase of polydimethylsiloxane remains an open question. A simple explanation for the evolution of low-temperature x-ray patterns is proposed. It includes a single crystalline phase and changes in crystalline texture. A fundamental issue is the orientation of polymer chains in the crystal unit cell.