parts of ethylene glycol were placed in reactor which then were esterified for 4 hours by heating to 140 230 u00b0 c with stirring after being adding 0 04 weight parts of antimontrioxide and 0 015 weight parts of phosphoric acid per weight part of ethylene glycol the esterified mixture was subjected to polycondensation at 230 285 u00b0 c for 4 hours under vacuum to give polyester i the polyester i was solidified with liquid nitrogen and pulverized to a powder thereafter 80 weight parts of the powder were homogeneously mixed for 30 min with 20 weight parts of calcium oxide particles ranging in size from 0 01 to 50 u03bcm with an average size of 0 4 u03bcm followed by allowing the homogeneous mixture to go through a twin screw melt extruder which was being operated at 240 290 u00b0 c under vacuum to give polyester ii 90 weight parts of the polyester i and 10 weight parts of the polyester ii were mixed dried at 160 u00b0 c for 6 hours with hot air melted through a melt extruder which was being operated at 290 u00b0 c and spun through a spinneret to give 75 24 polyester fibers 75 24 polyester fibers were prepared in a similar manner to that of example i except that 95 weight parts of the polyester i and 5 weight part of the polyester ii were used 100 weight parts of terephthalic acid and 45 weight parts of ethylene glycol were placed in a reactor which then were esterified for.