Study On Glycolic Acid(Methyl Glycolate) Polymerization Technology

As a kind of biodegradable engineering plastics,polyglycolic acid(PGA)and polyglycolate esters are widely used in the fields of oil and gas exploitation,packaging materials and medicine because of their excellent biocompatibility,biodegradability,good mechanical properties and good gas barrier.Polyglycolic acid is usually produced by open ring polymerization with complex technology,while melt polymerization is not used on a large scale due to its technical defects although it is cheaper.In this paper,the catalyst and polymerization process of polyglycolic acid and its esters were studied based on the fusion/solidification process.1.Poly(methyl glycolate)was prepared by melting polymerization using methyl glycolate as raw material.The influences of catalyst type and catalyst dose on the synthesis of poly(methyl glycolate)were discussed in the melting polymerization stage.The optimum reaction conditions for the preparation of poly(methyl glycolate)by melting polymerization were determined as follows:catalyst stannous oxalate,reaction temperature 180 ℃,m(glycolate):m(stannous oxalate)=1:0.5%.The yield was 74.25%,Mw= 8420,PD= 3.41.Compared with the degradation ability of polymethyl glycolate prepared by inorganic tin catalyst,the degradation performance of polymethyl glycolate was more controllable and more conducive to the application in production and life.2.Using polymethyl glycolate obtained by melt polymerization as raw material,solid phase polymerization was used to further promote the molecular weight growth of polymethyl glycolate.The influences of catalyst dose,reaction temperature and reaction time on the synthesis of polymethyl glycolate were discussed,and the optimal reaction conditions for the preparation of polymethyl glycolate by solid phase polymerization were determined as follows: The reaction temperature was 190 ℃,the reaction time was 15 h,m(polymethyl glycolate):m(stannous oxalate)= 1:0.2%,and the final yield of polymethyl glycolate was 88.25%,Mw= 20341,PD= 3.10.The molecular weight of polymethyl glycolate was increased by melting/solid polymerization method.3.Glycolic acid was used as raw material to prepare macromolecular initiator catalyzed glycolic acid polymerization to produce polyglycolic acid.The effects of molecular weight of macromolecular initiator,tin content and proportion of macromolecular initiator on glycolic acid melting polymerization were discussed,and the optimal reaction conditions for using macromolecular initiator to produce polyglycolic acid were determined as follows: The tin content of macromolecular initiator was 0.59wt%,the molecular weight was 7642,the reaction temperature was 190 ℃,m(polyglycolic acid): m(macromolecular initiator)=1:5%,the yield of polyglycolic acid is 93.45%,Mw= 22861,PD= 3.32.The polyglycolic acid product prepared by macromolecular initiator has good performance and more controllable degradation.It is a new kind of polyester production catalyst.