tpa were separately introduced into the reactor and in examples c 4 and 5 a paste was made before introduction to the esterification vessel besides in comparative example b and examples c 4 and 5 the esterified material was removed from the esterification vessel and transferred to a polycondensation reaction vessel the catalyst was added only at the end of esterification comparative example b used a heel the experimental data and analytical data of these examples are also collected in the table table example a 1 2 3 b c 4 5 feed heel g u2014 u2014 u2014 u2014 5500 u2014 u2014 u2014 pdo g 315 315 315 315 4185 6278 6278 27200 tpa g 549 549 549 549 7310 10963 10963 47510 mole ratio 1 25 1 25 1 25 1 25 1 25 1 25 1 25 1 25 naoac mmole 2 u2014 u2014 u2014 u2014 u2014 u2014 2 88 coac mmole 2 8 05 lioh mmole 2 u2014 0 69 u2014 0 21 u2014 u2014 u2014 esterification ti added ppm u2014 u2014 40 40 u2014 u2014 u2014 40 temp u00b0 c 258 258 258 258 260 260 259 260 t 1 min 178 180 143 145 164 250 260 160 polycondensation ti added ppm 40 40 40 u2014 40 40 40 u2014 i 1076 ppm u2014 u2014 u2014 u2014 250 250 250 250 temp u00b0 c 258 258 258 258 253 253 253 250 p kpa 0.