关键词: 醇洗工艺, 重结晶, 异丙醇, 乙交酯, 开环聚合, 醇洗工艺, 重结晶, 异丙醇, 乙交酯, 开环聚合

Abstract: Crude glycolide which obtained via melting depolymerization was purified by alcohol washing. The effects of times of washing,amount of solvent,washing time on contents of free acid and H₂O in glycolide and yield of glycolide were investigated. The effect of total hydrogen content on ring opening polymerization was also discussed. Isopropanol was chosen as the proper solvent for crude glycolide purification by comparing different alcohol solvents first,and purified glycolide was obtained by filtration and vacuum drying. The optimized purifying conditions were as follows:washing 3 times by alcohol,V(Alcohol)/M(Glycolide)=2mL/g and washing time for 30min in each time. The contents of free acid and H₂O in glycolide were reduced to 17×10^-6mol/g,and 468mg/L respectively,and total hydrogen content was 1.7×10^-5mol/g. Through ring opening polymerization in twin screw extruder,glycolide was converted to PGA with high intrinsic viscosity of 0.81dL/g. After purification of glycolide via alcohol washing,the yield was 82%,higher than that of the recrystallization process. Differential scanning calorimetry (DSC) was used to determine glycolide purity with average value of 99.93%,meeting the needs of ring opening polymerization.

Key words: alcohol washing process, recrystallization, isopropanol, glycolide, ring opening polymerization, alcohol washing process, recrystallization, isopropanol, glycolide, ring opening polymerization