BLOCK COPOLYETHERESTERS .3. PREPARATION OF BLOCK COPOLYETHERESTERS BYA TEREPHTHALIC ACID PROCESS IN THE PRESENCE OF SALTS

The block copolyetheresters with hard segments of poly(butylene tereph thalate) and soft segments of poly(tetramethylene ether) were prepared by a terephthalic acid (TPA) process in the presence of some salts. T he preparations of a block copolyetherester under various conditions w ere first studied in a 1 L stainless steel reactor to find the best me thod. Then, the preparations of four block copolyetheresters were run in a pilot plant comprising a 200 L polyesterification reactor and a 2 00 L polymerization reactor under the suitable condition. The presence of some salts reduced the formation of tetrahydrofuran (THF), and als o reduced the total reaction time in the pilot plant. The thermal prop erties and various mechanical properties of the block copolyetherester s prepared by the pilot plant were investigated to evaluate the feasib ility of this method.