Determination of diethylene glycol in polyethylene tere-phthalate - after hydrolysis in aq. soln. with alkaline earths

摘要

Samples for gas chromatographic(GC) determination of diethylene glycol content of polyethylene terephthalate (PET) are prepared from a suspension of 5g. finely-ground polymer, 10 ml. water and around 0.1 g-equiv. alkaline earth hydroxide, by partial hydrolysis under reflux for around 20 mins. followed by neutralising the warm soln. with CO2 and filtering. Dissolution time of the polymer is reduced from over 16 h., allowing results to be obtained in time to modify the polymerise. process. Applicn. of pressure during hydrolysis is unnecessary and the alkaline catalyst is ppted. by CO2 instead of passing into the filtrate where it can cause blockage of GC columns.