The effects on thermal stability of polyglycolic acid by adding dihydrazide metal chelators

To improve the thermal stability of Polyglycolic Acid (PGA) during processing, 3 dihydrazide metal chelators were synthesized and melt mixed with PGA by the twin-screw extruder. The most appropriate metal chelator was selected and the processing parameters, such as supplementation and screw speed, were optimized through thermal gravity analysis (TG). The isothermal kinetic parameters were calculated as well. As a result, N, N-bis (salicyloyl) dodecanedioic acid dihydrazide is the proper metal chelator. Compared with the blank sample of PGA, the remaining molecular weight percentage increased from 62.8% to 79.2% and the tensile strength was promoted from 76.78 MPa to 117.02 MPa when the metal chelator content was 0.008 mmol/g and the screw temperature and speed were set as 230 °C and 20 rpm. After calculating, the activation energy of pure PGA and PGA-containing the metal chelator is in the ranges of 40.10-65.30 kJ/mol and 42.89-88.87 kJ/mol respectively.