Enthalpy of formation and disordering temperature of transient monotropic liquid crystals of poly(butylene 2, 6-naphthalate). (5th December 2018)

• Record Type: Journal Article
• Authors: Androsch, René; Soccio, Michelina; Lotti, Nadia; Jehnichen, Dieter; Göbel, Michael; Schick, Christoph
• Is Part Of: Polymer. Volume 158(2018)
• Page Start: 77
• Page End: 82
• Publication Date: 2018-12-05
• Subjects: Poly(butylene 2, 6-naphthalate) -- Liquid crystal -- Crystallization -- Fast scanning chip calorimetry; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2018.10.037
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Melt-crystallization of poly(butylene 2, 6-naphthalate) (PBN) at temperatures lower than about 160 °C follows Ostwald's rule of stages via intermediate formation of a smectic liquid crystalline phase (LC-phase). The transient LC-phase has been isolated by interruption of the isothermal crystallization process at 140 °C at sub-second timescale, and then its disordering was analyzed on heating at a rate of 2000 K/s, which suppresses the transition into α-crystals. The disordering temperature of the LC-mesophase is slightly lower than 200 °C, and as such 20–30 K lower than the melting temperature of α-crystals formed from the LC-phase at 140 °C. Analysis of the bulk enthalpy of formation of the LC-phase revealed that it covers only 20–25% of the total bulk enthalpy of crystallization, which is considered further proof of its smectic nature. Graphical abstract: Highlights: Crystallization of PBN below 160 °C follows Ostwald's rule of stages. Crystallization below 160 °C proceeds via formation of a liquid crystalline (LC) phase. Disordering of the LC-phase was analyzed on fast heating, suppressing the transition into crystals. Disordering of the LC-phase occurs 20–30 K lower than melting of α -crystals. The bulk enthalpy of LC-phase formation is about 20–25 % of that of crystallization.