Property modulation of poly (trimethylene terephthalate) by incorporation of nonlinear isophthalate units

P(TT-co-TI)s with up to 20 mol-% of TI units were synthesized in order to modulate the thermal and mechanical properties of PTT and were characterized by FT-IR, H-1 NMR, DSC, and DMA analysis. PTI and PTT were also synthesized for the purpose of comparison. The polymerizations proceeded via two steps, i.e., transesterification and polycondensation. Manganese acetate and titanium butoxide were used as catalysts for the transesterification and polycondensation steps, respectively. During the polymerization, the P(TT-co-TI) copolymers and PTI exhibited similar transesterification rates, whereas PTI showed a slower rate. The polycondensation rate decreased with increasing TI content in P(TT-co-TI). The synthesis of the polymers was confirmed by FT-IR and H-1 NMR analysis. DSC and DMA analysis indicated that the P(TT-co-TI)s are random copolymers, and that their T-cc increased and T-m decreased as the TI content in the P(TT-co-TI) increased. The peel strength between the P(TT-co-TI) films and an aluminum sheet increased as the TI content in the copolymer increased. The melt-quenched films of the PTT and P(TT-co-TI) copolymers had similar tensile strengths and initial moduli. The dyeing property of the P(TT-co-TI) films was enhanced by increasing the TI content.