On the Interrelationship of Transreactions with Thermal Properties and Dynamic Mechanical Analysis of PTT/PEN Blends

• Published in: Macromolecular chemistry and physics 2009-08, Vol.210 (16), p.1291-1302
• Main Authors: Jafari, Seyed-Hassan, Khonakdar, Hossein Ali, Asadinezhad, Ahmad, Häußler, Liane, Böhme, Frank, Komber, Hartmut
• Format: Article
• Language: English
• Subjects: Applied sciences; Blending; Blends; Crystallinity; Crystallization; Dynamic tests; Dynamics; Exact sciences and technology; Organic polymers; Phases; Physicochemistry of polymers; poly(ethylene naphthalate); poly(trimethylene terephthalate); polyesters; Polymer blends; Properties and characterization; reactive processing
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.200900095

An attempt was made to explore the effects of interchange reactions on the crystallization, melting, and dynamic mechanical behavior of binary blends based on poly(trimethylene terephthalate) (PTT)/poly(ethylene 2,6‐naphthalate) (PEN). 1H NMR spectroscopy is used to verify the occurrence of interchange reactions at the interface, which are increased upon an increase in the melt processing time and temperature. The crystallinity of PTT was reduced while that of PEN was increased on blending. In addition, the crystallization temperatures of both phases showed depression. A single composition‐dependent glass transition temperature (Tg) was detected in the second and subsequent heating thermograms of the blends, which is indicative of miscibility. The cold crystallization of the PTT phase was observed to increase while that of PEN was suppressed on blending. Each phase crystallized individually and a melting point depression was evident, which suggests a certain level of miscibility. Dynamic mechanical thermal analysis corroborated differential scanning calorimetry results. A constructive synergism was observed in the glassy state storage moduli of the blends, which is suggestive of a reduced specific volume of the system because of enhanced interactions and crystallinity. This paper presents a quantitative estimation of the extent of transesterification in PTT/PEN blends that have been processed under different melt processing conditions. The results clearly show that transesterification does occur in these blends and that it has an influence on the morphology and properties of the materials. A relationship between transesterification and phase structure and crystallization has been well established.