Dong Wook Chae  Kyung Rak Choi  Byoung Chul Kim

Vol. 54,  No. 3, pp. 191-198, Jun.  2017
10.12772/TSE.2017.54.191

PET PTT ester exchange reactions Blends Thermal properties

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Poly(ethylene terephthalate) (PET) and poly(trimethylene terephthalate) (PTT) were melt blended at 280 ℃ at varying blending time and ratio. The resulting physical properties were examined in relation to ester exchange reactions. The PET/PTT 50/50 blends (by weight percentage) exhibited double melting peaks (Tm) up to 30 min blending time beyond which they were merged to one broader peak. The melting peak had a nearly linear relationship with blending time and displayed a much steeper decrease for ET units than for TT units. Two new peaks for asymmetric aromatic carbons were detected in 13CNMR spectra and their intensity increased notably from 40 min blending time which was consistent with thermal analysis. The dissolution of copolyesters occurred even after 10min blending time and its degree increased with blending time. FESEM images of chloroform etched fracture surfaces displayed coarse and continuous phase properties from 40 min blending time while losing the spherical shape of each component. In the DSC measurement of the PET/PTT blends prepared at various ratios at a given blending time of 20 min, all the blends exhibited a single glass transition temperature (Tg) more consistent with the Gordon–Taylor equation than the Fox equation. In addition, a single Tm peak was observed in each sample, except for 50/50 composition, which shows the coexistence of Tm for each component. All blends except for 50/50 exhibited a similar WAXD patterns to their rich component. This was evidenced by solubility test results showing the highest solubility for 50/50 blends. This phenomenon was also confirmed in FESEM measurement of chloroform etched fracture surfaces where the blends composed of an equal amount of the component exhibited coarse and dumbbell-like domains.