Patent ID: 8318837

Claim:
A method of estimating a moisture resistance of polyglycolic acid resin, comprising the steps of: measuring a glycolide content (wt. %) in a sample polyglycolic acid resin by subjecting a solution of the sample polyglycolic acid resin to gas chromatography; measuring a terminal carboxyl group concentration (equivalent/ton) of the sample polyglycolic acid resin by titrating a solution of the polyglycolic acid resin with sodium hydroxide; calculating a total carboxyl group-source concentration X (equivalent/ton) in the polyglycolic acid resin according to formula (2) below: X =the measured glycolide content (wt. %)×54+the measured terminal carboxyl group concentration (equivalent/ton) (2); calculating a molecular weight retentivity Y (%) after standing for 3 days in an environment of 50° C. and 90% relative humidity according to formula (1) below: Y =0.011 X 2 −1.5 X +74; (1); and estimating the moisture resistance of the polyglycolic acid resin in terms of the calculated molecular weight retentivity Y (%).