Novel impacts of glycol-modified poly(ethylene terephthalate)(PETG) to crystallization behavior of polyethylene naphthalate (PEN) within stretched miscible blends

• Published in: Polymer (Guilford) Vol. 53; no. 13; pp. 2758 - 2768
• Main Authors: Jheng, Li-Cheng, Yang, Chun-Yen, Leu, Ming-Tsong, Hsu, Keng-Hao, Wu, Jyh-Horng, Ruan, Jrjeng, Shih, Kuo-Chen
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 07.06.2012; Elsevier
• Subjects: Activated; Applied sciences; Blends; Crystallization; Diluent effect; Exact sciences and technology; Heating; Lamellar association; Order disorder; Organic polymers; Physicochemistry of polymers; Polyethylene naphthalate; Polymer blends; Properties and characterization; Segmental sliding; Segments; Segmental sliding; Lamellar association; Diluent effect; Polymer blends; Alkyl terephthalate copolymer; Crystallization; Nanostructure; Crystallinity; Experimental study; Structure composition relationship; Ester copolymer; Oriented polymer; Naphthalate polymer; Supramolecular structure; Miscibility; Oriented copolymer; Thermodynamic properties; Ethylene terephthalate copolymer
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2012.04.035

For studied blends of amorphous glycol-modified poly(ethylene terephthalate) (PETG) and semicrystalline polyethylene naphthalate (PEN), melt miscibility is understood from the linear variation of a single glass transition temperature (Tg) over the entire composition range. The diluent effect of PETG component severely retarded the crystallization of PEN component within blends. Nevertheless, after being through isothermal stretching at 120 °C, crystallization was able to progress efficiently during heating in a continuous manner. Instead of being thermally relaxed back to amorphous state, parallel sliding motions of stretched PEN segments toward crystallization appear rather dominant. Within stretched blends, the PETG content emerged as a critical factor to the crystallinity increase of PEN fraction and the absence of lattice defect, instead of behaving as a diluent component. Furthermore, as being indicated by in-situ small-angle X-ray experiments, regular lamellar stacking gradually developed within stretched blends through heating, which indicates the involvement of thermally activated self-association of randomly distributed crystalline lamellae. With including a higher fraction of PETG component, these secondary ordering processes including lamellar thickening can be activated at lower temperature. Hence, the accompanied thermal relaxation of flexible PETG segment is inferred able to lubricate the sliding of stretched PEN segments in amorphous regions via lowering encountered frictional hindrance, and thus enhance both primary and secondary ordering processes within stretched blends. [Display omitted]