Thermal Properties and Alkaline Weight Reduction of Anionic Copolyesters/Dodecylbenzenesulfonate Blend Films

Abstract: A series of anionic copolyester/dodecylbenzenesulfonate (DBS) blend films were prepared by a melt-com-pounding method and then annealed under a range of conditions. To eliminate possible experimental errors in measur-ing the alkaline reduction rate of the samples, the crystallinity should be uniform. We used Fourier transform infrared(FT-IR) spectroscopy to measure and control the relative crystallinity of the annealed samples. The relationshipbetween the crystallinity and reduction rate, as well as the annealing conditions of the annealed blend samples, wasderived. FT-IR analysis showed that the crystallization rate of copolyester/DBS blend films is lower than that of purecopolyester. However, the alkaline weight reduction rate of the blend films, which have similar crystallinities, increasesdramatically with increasing DBS content, even at a low DBS content of 1 to 3 wt%, although the effect of the DBSbecomes negligible above 5 wt%. However, unlike the result for annealed films, the alkaline weight reduction rate foramorphous films exhibited a linear relationship between the alkaline reduction rate and the DBS content for all of theexamined DBS content, demonstrating that the effects of the DBS on the alkaline weight reduction of the copolysestercould be affected by processing conditions such as post-drawing and annealing. Keywords: anionic copolyesters, DBS, annealing, alkaline weight reduction, FT-IR