| Abstract: | Properties of poly(ethylene 2,6‐naphthalate) (PEN) and its copolymers containing diethylene glycol (DEG), propanediol (PD), butanediol (BD), and bisphenol A ethoxylate (BSA) were investigated. The copolymer composition was determined by 1H‐NMR spectroscopy. It has a higher value than the feed composition due to the high volatility of ethylene glycol (EG). The melting temperature of the copolymers was gradually depressed with the increase of dialcohol in the composition. The complex viscosity of the copolymers did not depend on the molecular weight, but on the chemical structure. The complex viscosity of the copolymers containing 3 mol % of DEG, BD, and 5 mol % of BD was lower than that of PEN, and the mechanical properties were similar with the value of PEN. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2900–2905, 1999 |
