Ws. Lyoo et al., Effect of copolycondensation temperature on the reactivity ratios of bis(4-hydroxybutyl) terephthalate and bis(2-hydroxyethyl) terephthalate, POLYM BULL, 42(1), 1999, pp. 9-16
The effect of copolycondensation temperature on the monomer reactivity rati
os of bis(4-hydroxybutyl) terephthalate (BHBT) and bis(2-hydroxyethyl) tere
phthalate (BHET) was investigated at 260, 270, and 280 degrees C, in the pr
esence of titanium tetrabutoxide as a catalyst. Adopting 2nd order kinetics
to polycondensation, the rate constants of polycondensation of BHBT and BH
ET, k(11) and k(22), were calculated to be 2.58, 1.30; 3.87, 2.24; and 5.29
, 4.06 min(-1). In addition, the rate constants k(12) and k(21) of cross re
actions could be determined as 0.91, 3.00; 1.49, 4.42; and 2.13, 5.85 min(-
1) from a proton nuclear magnetic resonance spectroscopic analysis. The mon
omer reactivity ratios of BHBT were much larger than those of BHET, indicat
ing the block nature of the copolycondensation, but the differences between
monomer reactivity ratios were decreased with increasing polycondensation
temperature, indicating that a probability of randomization was increased.